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The study of high-pressure sound velocity is an important part of shock wave physics, and the study of ultra-high pressure sound velocity of iron is of great significance to many research fields such as geophysics, solid state physics, and crystallography. At present, the measurement of sound velocity is usually carried out by the catch-up sparse wave method and windowed VISAR technology, which is complex in structure and not highly adaptable. In particular, for the ultra-high pressure sonic velocity measurement of metals, it is limited by the loading platform and window materials and cannot realize the high temperature and high-pressure environment of the earth's inner core. In this paper, the sound velocity measurement of iron under high temperature and high-pressure environment (78 GPa) is realized based on the two-stage light gas cannon experimental platform. The side-side sparse wave method was used to establish a coupling model of high-spatially resolved optical group and fiber bundle. A multiplexed all-fiber laser interferometry velocity measurement system (DISAR) was built, and the spatial resolution was better than 20 μm. In this paper, we will provide a feasible route for a method for measuring the high spatiotemporal resolution velocity. [ABSTRACT FROM AUTHOR]

Based on previous studies, we established a thermodynamic model to calculate the equation of state (EOS) and longitudinal sound velocity (Vp) for liquid Fe and Fe -8. 6Si under high temperature and pressure. The calculated EOSs and Vp are consistent with measurements by static and dynamic compressions. Under the outer core conditions, EOS and V, of liquid Fe-8. 6Si simultaneously match the seismic data of the Earth's out- er core. If Si is the only light element, its maximum concentration in the outer core is estimated to be 7.6~8.6 wt%. [ABSTRACT FROM AUTHOR]

Elastic properties of Si0.95H0.21O2 with hydrogarnet substitution (4H+ = Si4+) across the post‐stishovite transition (28–42 GPa) are determined up to 70 GPa using ab initio calculations and a pseudo‐proper type Landau model. At 28 GPa, elastic coefficients C11 and C12 converge, and the average shear and compressional velocity (VS and VP) decrease by a maximum of 25.5% and 5.2%, respectively. Hydrogarnet substitution reduces ambient elastic moduli and sound velocities, and shifts shear softening to lower pressure. 2%–13% Si0.95H0.21O2 may cause a VS anomaly of −0.5% to −2.6% at 700–820 km depth, explaining low VS layers beneath North America and the European Alps. Additionally, 20 vol % SiO2 in subducted basalt, with decreasing water content from 3.2 wt% to zero, could cause a VS anomaly of up to −7(4) % from 700 to 1,900 km depth, aligning with seismic scatterers identified in some subduction regions. Plain Language Summary: Our study explores the elasticity of stishovite and post‐stishovite (high‐pressure forms of SiO2) with 3.2 wt% water (Si0.95H0.21O2) up to 70 GPa using theoretical methods. During the transition from stishovite to post‐stishovite (28–42 GPa), shear softening occurs, and shear wave speed (VS) decreases by up to 25.5%. The direct hydrogen substitution for silicon can lower the ambient seismic wave speed and shift shear softening to lower pressure. A small amount of Si0.95H0.21O2, when present in the top lower mantle, could display low VS under North America and the European Alps, as identified by seismologists. Also, subducted mid‐ocean ridge basalt with lower H2O content in SiO2 from 700 to 1,900 km depth might account for seismically observed negative VS anomalies in certain subduction regions. Key Points: Elasticity of Si0.95H0.21O2 with 4H+ = Si4+ across the post‐stishovite transition is studied by ab initio calculation and Landau theoryElastic coefficient C11 converges with C12 and shear wave velocity VS decreases by 25.5% at 28 GPa in Si0.95H0.21O2Low VS layers and small‐scale VS anomalies in the shallow lower mantle could be caused by the post‐stishovite transition in hydrous SiO2 [ABSTRACT FROM AUTHOR]

A theoretical model is proposed in this work for the evaluation of composition‐dependent thermophysical properties such as the isothermal compressibility, velocity of sound and Debye temperature of liquid binary alloys. Using a square‐well (SW) model potential function under mean spherical model approximation, the composition‐dependent atomic‐level structural functions of Al1‐xCux, Ag1‐xCux, Au1‐xCux, Ag1‐xAlx, and Au1‐xAgx alloys have been determined and compared with available experimental data. An extensive computation was done to calculate the composition‐dependent isothermal compressibility through the structure factor in the long wavelength limit (k→0), and then we employed this data to investigate the velocity of sound in the considered melts. This yields the fundamental maximum frequency with which the constituent particles are vibrating in the melts and is used to determine the composition‐dependent Debye temperature, ΘD. The computed Debye temperature of considered melts using the Square‐well potential function is found to be in satisfactory agreement with the available DFT and MD simulation results. [ABSTRACT FROM AUTHOR]

In a binary liquid mixture containing pyrimidine-substituted azetidinone ultrasonic velocities, densities, and viscosities have been measured by unit of molality azetidinone at temperatures T = (298.15, 308.15, and 313.15 K). 3-chloro-4-(4-nitrophenyl)-1-(pyrimidin-2-yl)azetidin-2-one (AT1) and 3-chloro-4-(4-chlorophenyl)-1-(pyrimidin-2-yl)azetidin-2-one (AT2) in N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) were studied. The density, dynamic viscosity, and ultrasonic sound velocity have all been measured, among other acoustical and thermodynamic properties. Gibbs free energy of activation (ΔG*), enthalpy of activation (ΔH*), and entropy of activation (ΔS*) values have been studied further to determine how solvent changes and structural modifications impact these values. The molecular interactions between the components of the liquid combination have been used to explain these findings. [ABSTRACT FROM AUTHOR]

Copyright of Electronic Components & Materials is the property of Electronic Components & Materials 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.)

The species and contents of the light elements within the metallic cores play a crucial role in understanding the structure, thermal state, geodynamo, and evolution of the terrestrial planets and satellites. While silicon (Si) has been considered as a primary candidate light element in the cores of small terrestrial bodies, the sound velocities of face‐centered cubic (fcc) Fe‐Si are rarely investigated. Here we measured the compressional (VP) and shear (VS) wave velocities of Fe alloyed with 3 wt.% and 6 wt.% Si up to 6.3 GPa and 1,273 K using pulse‐echo overlap technique coupled with energy‐dispersive X‐ray diffraction. The incorporation of Si could increase the VP of body‐centered cubic (bcc) Fe by 0.074(15) km/s and decrease the VS by 0.024(9) km/s with each weight percent Si at 300 K. However, 3 wt.% Si has minimal effect on the VP of fcc‐Fe if not negligible. The incorporation of 6 wt.% Si stabilizes the Fe in mixture bcc and fcc phases at high temperature and increases the VP by 0.59 km/s compared with that of fcc‐Fe. Based on the Apollo seismic observation and VP of Fe and Fe‐Si alloys, Si is unlikely to be the sole light element in the lunar core. The solid core of the Mercury would be in the fcc phase if the Si content is less than 3 wt.% and the VP profiles is 5.65–6.34 km/s. While 6 wt.% Si would stabilize the Mercury's core in mixed bcc and fcc phases, the VP profiles would be 6.17–6.85 km/s. Plain Language Summary: As typical bodies within the solar system, the Moon and Mercury share similar internal structures with the Earth, consisting of a crust, mantle, and core. Their solid metallic cores are considered to be mainly composed of Fe alloyed with a few weight percent Si. Therefore, the sound velocities of body‐centered cubic (bcc) and face‐centered cubic (fcc)‐Fe and Fe‐Si have been obtained under the core conditions of the Moon and Mercury in this study. Our results show that the incorporation of Si could increase the VP of fcc‐Fe. The incorporation of light element is expected to be lower the sound velocity of fcc‐Fe to reconcile the seismic observation of the lunar core. Consequently, the Si is unlikely to be the primary light element in the lunar core. For Mercury, the solid inner core may be in the fcc phase or mixture phases of bcc and fcc depending on the Si content. The corresponding VP‐ρ profiles have been constrained. Key Points: The effect of 3 wt.% and 6 wt.% Si on the sound velocity of Fe has been constrainedLunar core would be Si‐depleted because its seismic velocity is lower than fcc‐FeThe sound velocity profile of the Mercury's core was constrained by considering different Si content [ABSTRACT FROM AUTHOR]

One popular method of obtaining the acoustic parameters of seabed sediments is by measuring the sound velocity of sediment samples in a laboratory. However, the effects of environmental variation and physical perturbation on acoustic properties are typically neglected in the application of such measured acoustic parameters. In this study, sediment samples were collected from the Huanghai and Bohai seas to measure sound velocity both on the deck and in the laboratory using a digital sonic measuring system. Additionally, sediment compositions, physical and mechanical properties and microstructures were determined. Sound velocity comparisons between on-deck and laboratory measurements indicate that laboratory-measured velocities are generally higher than those measured on the deck, with differences ranging from 1.45 m/s to 130.05 m/s, due to the water loss and densification of sedimentary particles in laboratory settings. The discrepancy of sound velocities measured in the laboratory and on the deck also differ based on the types of sediments sampled. Overall, the discrepancy increases with measurement frequency, increasing average grain diameter and sand content, as well as with decreasing clay content. [ABSTRACT FROM AUTHOR]

Abstract Elastic properties of Si0.95H0.21O2 with hydrogarnet substitution (4H+ = Si4+) across the post‐stishovite transition (28–42 GPa) are determined up to 70 GPa using ab initio calculations and a pseudo‐proper type Landau model. At 28 GPa, elastic coefficients C11 and C12 converge, and the average shear and compressional velocity (VS and VP) decrease by a maximum of 25.5% and 5.2%, respectively. Hydrogarnet substitution reduces ambient elastic moduli and sound velocities, and shifts shear softening to lower pressure. 2%–13% Si0.95H0.21O2 may cause a VS anomaly of −0.5% to −2.6% at 700–820 km depth, explaining low VS layers beneath North America and the European Alps. Additionally, 20 vol % SiO2 in subducted basalt, with decreasing water content from 3.2 wt% to zero, could cause a VS anomaly of up to −7(4) % from 700 to 1,900 km depth, aligning with seismic scatterers identified in some subduction regions.

The study of high-pressure sound velocity is an important part of shock wave physics, and the study of ultra-high pressure sound velocity of iron is of great significance to many research fields such as geophysics, solid state physics, and crystallography. At present, the measurement of sound velocity is usually carried out by the catch-up sparse wave method and windowed VISAR technology, which is complex in structure and not highly adaptable. In particular, for the ultra-high pressure sonic velocity measurement of metals, it is limited by the loading platform and window materials and cannot realize the high temperature and high-pressure environment of the earth’s inner core. In this paper, the sound velocity measurement of iron under high temperature and high-pressure environment (78 GPa) is realized based on the two-stage light gas cannon experimental platform. The side-side sparse wave method was used to establish a coupling model of high-spatially resolved optical group and fiber bundle. A multiplexed all-fiber laser interferometry velocity measurement system (DISAR) was built, and the spatial resolution was better than 20 μm. In this paper, we will provide a feasible route for a method for measuring the high spatiotemporal resolution velocity.

This study discusses the transition toward the use of environmentally friendly refrigerants in low-temperature technology. It also considers a new environmentally friendly fourth-generation refrigerant trans‑1,3,3,3-tetrafluoropropene R1234ze(E) as an alternative to the R134a refrigerant common in chillers and heat pumps, as well as the R22 refrigerant in air conditioning systems. A technique has been developed for constructing a unified fundamental equation on the states of liquid and gas for trans‑1,3,3,3-tetrafluoropropene. Around the critical point, the proposed fundamental equation satisfies the requirements of the scale theory for asymmetric systems, and in the region of a rarefied gas, it is reduced to the virial equation of state. Based on this fundamental equation, tables of standard reference data on pressure, density, enthalpy, isobaric and isochoric heat capacities, entropy, heat of vaporization, and sound velocity of trans‑1,3,3,3-tetrafluoropropene in the region of state parameters in the temperature ranges of 169–420 K and pressure of 0.1–100 MPa were calculated. Several statistical characteristics have been calculated, namely, absolute mean deviation, systematic deviation, standard deviation, and root mean square deviation, characterizing the accuracy of the proposed fundamental equation in describing the experimental values of the equilibrium properties obtained in recognized international thermophysical centers. Evidently, the values of these statistical characteristics are significantly lesser than those of the corresponding characteristics of the international fundamental equations of state, provided in the literature, when describing the thermal and caloric experimental data of trans‑1,3,3,3-tetrafluoropropene. The estimated expanded uncertainties of the tabulated data based on the proposed fundamental equation were 0.26% for density, 0.57% for pressure, 1.7% and 1.2% for isochoric and isobaric heat capacities, respectively, and 0.38% for sound velocity. The results suggest that the proposed unified fundamental equation of state adequately conveys the thermodynamic characteristics of trans‑1,3,3,3-tetrafluoropropene over the specified range of temperatures and pressures. [ABSTRACT FROM AUTHOR]

We present an investigation of the electronic, optical, and mechanical characteristics of the nano-structured Gallium Phosphide (GaP) semiconductor. It has been reported that high pressures have an impact on the interesting features. In our investigation, the pseudo-potential method was employed. It has been demonstrated that the phonon frequencies and sound speeds of GaP depend on pressure. The recent study can aid in our understanding of how pressure impacts the properties of nano-structured GaP material and electronics. Our results generally demonstrate good agreement with the experiment. The optoelectronic applications in the high-pressure region could make use of the predicted properties. [ABSTRACT FROM AUTHOR]

Numerous factors influence the acoustic characteristics of seafloor sediments, necessitating a comprehensive study that combines theoretical analysis, laboratory measurements and in situ measurements to support acoustic prediction and inversion. In this study, a porosity-based effective density fluid model (P-EDFM) is established to analyze the variation of acoustic properties with the porosity of seafloor sediments. On the biases of P-EDFM, the attribute of measured sound velocity and acoustic attenuation coefficient of seafloor sediment in Series 9B of the SAX99 was well interpreted within the frequency range of 25-100 kHz. The in situ measured sound velocity ratio was well predicated by the P-EDFM in the East China Sea and Yellow Sea. It reveals that the in situ sound velocity ratio decreases with increasing bulk porosity and with decreasing bulk density. The scattering and differences in the acoustic attenuation coefficient measured in situ in seafloor sediments are found to be greater than those observed for sound velocity. After considering the influence of temperature in the P-EDFM, the prediction of in situ sound velocity aligns well with the measured dataset. While, the acoustic attenuation coefficient exhibits an inflection point, increasing initially and then decreasing with changes in porosity, similar to the observed pattern in Hamilton’s observation and estimation. By incorporating temperature and frequency influences, the in situ measurements of sound velocity of seafloor sediments are corrected into laboratory sound velocities by using the P-EDFM. The result reveals the sediment samples’ sampling and transmitting process has a much greater impact on the sound velocity of sandy sediment in the East China Sea compared to muddy sediment. Overall, P-EDFM can predict the in situ sound velocity and sound attenuation coefficient under different temperatures and frequencies, with a lower prediction error for sound velocity compared to sound attenuation coefficient. [ABSTRACT FROM AUTHOR]

The optical, mechanical, and lattice dynamic properties of nanostructured GaSb semiconductor have been determined. The influence of pressure on the Longitudinal and transversal sound velocities, reflectivity, phonon frequencies, micro-hardness, and the transverse effective charge has been investigated. The dependencies of bond-stretching force constant, bond-bending force constant, susceptibility, Cauchy ratio, Born ratio, effective charge, and ionicity on the pressure of zinc-blende GaSb semiconductor are also been studied. The calculations in the present work have been performed using the pseudo-potential method (EPM). Comparisons with the available experiment and other works show reasonable agreement. The studied properties of the considered material could be useful in optoelectronic applications. [ABSTRACT FROM AUTHOR]

Polycrystalline Na0.5K0.5NbO3 ceramics were prepared under the condition of 10 GPa and 1 050 T. The compression and shear wave velocities of the samples under various hydrostatic pressures were measured using ultrasonic interferometry. By fitting the third-order finite strain state equation, the bulk and shear moduli of polycrystalline Na0.5K0.5NbO3 and their pressure dependency were determined as 172.6 GPa, 54.6 GPa, 0.3 and 2.1, respectively. The sample shows a positive pressure dependence of Young's modulus. Based on the elastic modulus data, the Poisson's ratio was obtained as 0.342, indicating that the material was ductile and shows brittleness under high pressure. The Vickers hardness and fracture toughness also show positive pressure dependence. Using the empirical models, the Vickers hardness and fracture toughness of the ceramics were obtained as 2.40 GPa and 2.33 MPa⋅m1/2. Meanwhile, based on the elastic wave velocity and density data, the Debye temperature (513.1 K) and the Grüneisen constant (2.113) of Na0.5K0.5NbO3 ceramics were derived. Our results provide an experimental reference for evaluating the acoustic and elastic- related comprehensive properties of Na0.5K0.5NbO3 under high pressure, and a foundation for its engineering applications under extreme high-pressure conditions as well. [ABSTRACT FROM AUTHOR]

BiNiO3 is a perovskite material with potential applications in various fields. In this paper, the crystal structure, electronic structure and elastic constants of monoclinic BiNiO3 under different pressure have been studied by first-principles. The results show that applying pressure causes changes in bond length between atoms and crystal structure, and can cause electrons to transfer between atoms. In particular, the valence states of Bi and Ni may change. These changes may lead to the transformation of the material from a monoclinic structure to an orthorhombic structure. Under the action of pressure, the magnetic moment decreases from 1.00 μB to about 0.50 μB, and the decrease is the largest in the range of 5 ∼ 15 GPa, which indicates that the pressure has an effective modulation effect on the magnetic moment. In addition, the influence of pressure on the elastic constant is studied. The results show that pressure has a significant effect on the elastic constants along the matrix diagonal, and the elastic constant increases with the increase of pressure. Finally, the changes of sound velocity on the crystal planes [100], [010] and [001] of monoclinic crystal structure under pressure are also studied, and it is found that pressure can effectively regulate sound velocity. This study shows that the crystal structure and electromagnetic properties of BiNiO3 can be regulated by pressure.

The acoustic properties of seafloor sediments have always been important parameters in sound field analyses and exploration for marine resources, and the accurate acquisition of the acoustic properties of sediments is one of the difficulties in the study of underwater acoustics. In this study, sediment cores were taken from the northern South China Sea, and the acoustic properties were analyzed. Since traditional methods (such as regression equations or theoretical models) are difficult to apply in practical engineering applications, we applied remote sensing data to sound velocity prediction models for the first time. Based on the influencing mechanism of the acoustic properties of seafloor sediments, the sediments' source, type and physical properties have a great influence on the acoustic properties. Therefore, we replaced these influencing factors with easily accessible data and remote sensing data, such as parameters of granularity, distance to the nearest coast, decadal average sea surface productivity, water depth, etc., using deep neural networks (DNN) to develop a sound velocity prediction model. Compared with traditional mathematical analyses, the DNN model improved the accuracy of prediction and can be applied to practical engineering applications. [ABSTRACT FROM AUTHOR]

Fe–Ni–S–Si alloy is considered to be one of the plausible candidates of Mercury core material. Elastic properties of Fe–Ni–S–Si liquid are important to reveal the density profile of the Mercury core. In this study, we measured the P-wave velocity (VP) of Fe–Ni–S–Si (Fe73Ni10S10Si7, Fe72Ni10S5Si13, and Fe67Ni10S10Si13) liquids up to 17 GPa and 2000 K to study the effects of pressure, temperature, and multiple light elements (S and Si) on the VP and elastic properties. The VP of Fe–Ni–S–Si liquids are less sensitive to temperature. The effect of pressure on the VP are close to that of liquid Fe and smaller than those of Fe–Ni–S and Fe–Ni–Si liquids. Obtained elastic properties are KS0 = 99.1(9.4) GPa, KS’ = 3.8(0.1) and ρ0 =6.48 g/cm3 for S-rich Fe73Ni10S10Si7 liquid and KS0 = 112.1(1.5) GPa, KS’ = 4.0(0.1) and ρ0=6.64 g/cm3 for Si-rich Fe72Ni10S5Si13 liquid. The VP of Fe–Ni–S–Si liquids locate in between those of Fe–Ni–S and Fe–Ni–Si liquids. This suggests that the effect of multiple light element (S and Si) on the VP is suppressed and cancel out the effects of single light elements (S and Si) on the VP. The effect of composition on the EOS in the Fe–Ni–S–Si system is indispensable to estimate the core composition combined with the geodesy data of upcoming Mercury mission. [ABSTRACT FROM AUTHOR]

The ultrasonic transducer is an indispensably critical component for sound velocity measurement. With the increasing demand of high-temperature ultrasonic dual mode transducer applicable to cubic-anvil apparatus, where experiments of high-pressure and high-temperature sound velocity are routinely conducted, a PZT-based ultrasonic dual modetransducer was presented iii this study. It was made of a sandwich of two PZT piezoceramic wai'ers, the upper one generating P-waves and the lower one genet* ating S-waves. The transducer was directly bonded onto a WC anvil of cubic-anvil apparatus using high-temperature adhesive. and then heated in an oven while measuring the bottom echoes from the WC anvil. The results showed that the high-temperature transducer could work up to 140 °C. The transducer features low cost, easy fabricating, and highquality signals, and so we believe it is useful for sound velocity measurement at high temperatures in cubic-anvi] apparatus. [ABSTRACT FROM AUTHOR]

Adiabatic compressibility βS of the 4-methylpyridine + water solution is investigated in a wide concentration and temperature variation interval using Mandelstam–Brillouin scattering spectroscopy. The adiabatic compressibility minimum caused by the microinhomogeneous structure of the solution is experimentally established at the concentration of 0.06 molar fractions of 4-methylpyridine in the solution. The results of the investigations allow the construction of a diagram of possible states caused by a continuous three-dimensional hydrogen bond network of water. The results of experimental study of the excessive hypersound absorption in acetone + water and 3-methylpyridine + water solutions are discussed based on the conclusions of the theory of high-frequency sound scattering near the critical point (developed by Chaban) and the Landau theory. These results are described within the framework of the Landau and Chaban theories and explained by the existence of two different states with minimum thermodynamic stability in the solution. [ABSTRACT FROM AUTHOR]

Copyright of Natural Gas Industry is the property of Natural Gas Industry Journal Agency 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.)

The effects of light elements on the elastic properties of disordered binary hcp-Fe alloys were investigated at high pressures using plane-wave density functional theory combined with the Monte Carlo special quasi-random structure method. We found that the increase in the O content in hcp-Fe had a more pronounced effect on the sound velocity than Si, S, and C. The longitudinal wave velocity was decreased by ∼ 6% with 2% O content, which was a much greater decrease than the values of 0.6% and 2% induced by the same content of Si and S, respectively, under high pressures. Compared with the other three light elements, the longitudinal wave velocity of the Fe-C alloy exhibited the most gradual decreasing with increasing C content. In addition, the effects of different O and S contents on the anisotropy of hcp-Fe alloys strongly depended on the variation in pressure, whereas the pressure only slightly affected the anisotropy of Fe-Si alloy systems.

The present work analyses the absorption coefficient of sound waves and the speed of sound propagation in thermally modified wood. The high resistance to weathering, fungi, and better dimensional stability, and therefore the broad physical properties of this material, are well known. However, the literature lacks numerous analyses of its acoustic characteristics. During the study, high-density species, such as oak, red oak, and beech were used, in contrast to pine. Pine wood during this test was characterised by a most rapid increase in the sound absorption coefficient value, in the range of 1000–6300 Hz, and reached the highest value from all wood species. Among all species, the highest value of the examined parameter was obtained for beech wood and pine wood, which were 0.213 (at frequency 3 kHz) and 0.183 (at 6.3 kHz), respectively. The sound velocity decreased for all species only in the tangential direction. [ABSTRACT FROM AUTHOR]

Montmorillonite clay (MMT) has been widely used in engineering and environmental applications as a landfill barrier and toxic waste repository due to its unique property as an expandable clay mineral that can absorb water easily. This absorption process rendered MMT to be highly exothermic due to electrostatic interactions among molecules and hydrogen bonds between surface atoms. A detailed study of a large supercell model of structural clay enables us to predict long-term nuclear waste storage. Herein, a large solvent MMT model with 4071 atoms is studied using ab initio density functional theory. The DFT calculation and analysis clarify the important issues, such as bond strength, solvation effect, elasticity, and seismic wave velocities. These results are compared to our previous study on crystalline MMT (dry). The solvated MMT has reduced shear modulus (G), bulk modulus (K), and Young's modulus (E). We observe that the conduction band (CB) in the density of states (DOS) of solvated MMT model has a single, conspicuous peak at −8.5 eV. Moreover, the atom-resolved partial density of states (PDOS) summarizes the roles played by each atom in the DOS. These findings illuminate numerous potential sophisticated applications of MMT clay. [ABSTRACT FROM AUTHOR]

The present paper contains data on the density (ρ) , sound velocity (u) , and specific heat capacity c p of the mixture of N,N-dimethylformamide + 1-butanol (DMF + BuOH) determined in the entire concentration range of solution and in the temperature range (293.15–318.15) K. The analysis of thermodynamic functions such as isobaric molar expansion, isentropic and isothermal molar compression, isobaric and isochoric molar heat capacity, as well as their excess functions (E p , m E , K S , m E , K T , m E , C p ,   m E , C V ,   m E) and also V m E was undertaken. The analysis of changes in the physicochemical quantities was based on consideration of the system in terms of intermolecular interactions and resulting changes in the mixture structure. The results available in the literature were confusing during the analysis and became the reason for our decision to thoroughly examine the system. What is more, for a system whose components are widely used, there is very scarce information in the literature regarding the heat capacity of the tested mixture, which was also achieved and presented in this publication. The conclusions drawn from so many data points allow us to approximate and understand the changes that occur in the structure of the system due to the repeatability and consistency of the obtained results. [ABSTRACT FROM AUTHOR]

In this work, the sound velocity and some of the mechanical, optical and optical phonon frequencies of the semiconductor β-GaN have been studied. The proposed temperature dependency of the pseudopotential form factors was used together with the empirical pseudopotential technique (EPM). The precise form factors for each temperature are computed using the suggested model. Calculations have been done to determine the temperature-dependent values of the energy gaps, sound velocity, refractive index, elastic constants, mechanical moduli, phonon frequencies and dielectric constants. The findings and the published and experimental data in the literature are in good agreement. These findings can be used as a guide for physical parameter values that are difficult to quantify experimentally. [ABSTRACT FROM AUTHOR]

In the work, hydrodynamics equations approximation was carried out based on the calculation of the distribution of water flow velocities in different time layers. A study of the stability of equation difference scheme for calculating the pressure by the Rote method was carried out. The error of equation approximation for pressure calculation is estimated. The accuracy of the numerical solution of the problem, built on the basis of a three-layer difference scheme, depends on the error in the approximation of the initial conditions and the error accumulated during transitions between time layers. An estimate of the approximation order of the initial conditions using a change of variables is carried out. An estimate of approximation error by the difference scheme of the hydrodynamic model was obtained by expanding the functions in a Taylor series. [ABSTRACT FROM AUTHOR]

The elastic behavior of a material can be a powerful tool to decipher thermal transport. In thermoelectrics, measuring the elastic moduli—directly tied to sound velocity—is critical to understand trends in lattice thermal conductivity, as well as study bond anharmonicity and phase transitions, given the sensitivity of elastic moduli to the chemical bonding. In this review, we introduce the basics of elasticity and explain the origin of high‐temperature lattice softening from a bonding perspective. We then review elasticity data throughout classes of thermoelectrics, and explore trends in sound velocity, anharmonicity, and thermal conductivity. We reveal how experimental sound velocities can improve the accuracy of common thermal conductivity models and present a critical discussion of Grüneisen parameter estimates from elastic moduli. Readers will be equipped with tools to leverage elasticity measurements or calculations to accurately interpret thermal transport trends. [ABSTRACT FROM AUTHOR]

In this study, the interactions in aqueous binary and ternary systems containing polyethylene glycol (6000) and erythromycin at different temperatures were investigated to utilize this information in the aqueous two-phase method for different purposes, including separation and purification. Through experimental methods, density, sound velocity, and viscosity at 293.15, 303.15, and 313.15 K were measured in aqueous solutions, including erythromycin and polyethylene glycol. From the experimental density data, apparent molar volume (ϕV), limiting apparent molar volume (ϕV0) and transfer molar volume ( ∆ t r ϕ V 0) have been calculated. Also, the experimental sound velocity data determined apparent molar isentropic compressibility (ϕk), limiting apparent molar isentropic compressibility (ϕk0) and transfer isentropic compressibility ( ∆ tr ϕ k 0) values of polyethylene glycol (6000) from water to erythromycin solutions. Furthermore, experimental viscosity data and the Jones–Dole equation determined viscosity β′-coefficient and transfer viscosity β′-coefficient ( ∆ t r β ′) values. The obtained results investigated the polymer effect as kosmotropic or chaotropic on erythromycin drug and the interaction between polyethylene glycol and erythromycin (solute-solute interactions). The results show that the interaction between drug and polymer is more desirable in the high-concentration polymer. Finally, results indicate that polyethylene glycol (6000) has played a kosmotropic role in aqueous solutions of erythromycin. [ABSTRACT FROM AUTHOR]

We propose a simple two-step approximation for the radial distribution function of a one-component two-dimensional Yukawa fluid. This approximation is specified by the key parameters of the system: coupling parameter and screening parameter. On the basis of this approximation, analytical expressions are obtained for the same thermodynamic quantities as internal energy, internal pressure, excess entropy in the two-particle approximation, and also longitudinal sound velocity. The theoretical results show an agreement with the results obtained in the case of a true radial distribution function. [ABSTRACT FROM AUTHOR]

We present a picosecond optoacoustic technique for mapping both the longitudinal sound velocity v and the refractive index n in solids by automated measurement at multiple probe incidence angles in time-domain Brillouin scattering. Using a fused silica sample with a deposited titanium film as an optoacoustic transducer, we map v and n in the depth direction. Applications include the imaging of sound velocity and refractive index distributions in three dimensions in inhomogeneous samples such as biological cells.

MoS2/MoSe2 superlattice is a potential candidate for thermoelectric materials. We have theoretically constructed MoS2/MoSe2 vertical and lateral superlattices based on the density functional theory. Here, five possible stacking structures of MoS2/MoSe2 vertical superlattice are considered. The optimized energy of AA1 structure is the lowest. The structural stability, electronic and mechanical properties of AA1 structure and lateral superlattice (LS) are studied. The results shows that AA1 and LS are thermodynamically, dynamically and mechanically stable. The calculated band structures display AA1 is an indirect bandgap semiconductor, while LS is a direct bandgap semiconductor. Furthermore, the sound speed of LS is slightly lower than that of AA1. The sound velocity of LS has a little anisotropy and is minimum in the [01] direction.

The applicability of laser ultrasonics for the determination of grain size and phase composition in steels under different temperatures was investigated. This was done by obtaining the velocity and attenuation of propagating ultrasonic waves in a simulated steel medium. Samples of ferrite and austenite with varying microstructures were modelled and simulated with the finite difference method, as were samples with varying ratios of austenite and martensite. The temperature of the medium was taken into account as an essential parameter, since both velocity and attenuation are temperature dependent. Results of the velocity and attenuation analysis showed that the use of the wave propagation velocity is not feasible for determination of grain size or phase composition due to a high sensitivity to temperature and sample thickness. The frequency-dependent ultrasonic wave attenuation was less sensitive to the variation of temperature and sample thickness. It can be concluded that accurate knowledge of the temperature is essential for obtaining a correct grain size or phase ratio estimation: a temperature accuracy of 100 °C yields a grain size accuracy in the order of a micrometer using the attenuation. Similarly, a temperature accuracy of 70 °C leads to a phase ratio estimation accuracy of 10%. [ABSTRACT FROM AUTHOR]

It is well known that polar organic compounds, such as alcohols and polyols, exert an appreciable influence on water structure and thus have important effects on surfactant micellization. These substances are often used to modify the properties of surfactants in aqueous solutions, increasing the practical applications they have in diverse industries. In this work, the critical micelle concentration (CMC) of decyltrimethylammonium bromide (C10TAB) in water and in 1,2-propanediol aqueous solutions was determined from both sound velocity and surface tension measurements as a function of surfactant concentration in the temperature range of (293.15 to 308.15) K. The critical micelle concentration of the surfactant increases as the concentration of 1,2-propanediol becomes higher, while the effect on temperature does not show important changes within the range considered. At the selected temperatures, the standard thermodynamic parameters of micellization suggests that the addition of 1,2-propanediol makes the micellization process less favorable. Thermodynamic analysis suggests that the micelle formation of C10TAB is an entropy-driven process at the temperatures considered in this study. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ordnance Equipment Engineering is the property of Chongqing University of Technology 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.)

Isobaric specific heat capacity (Cp) is an important parameter not only in physics but also for most materials. Its accurate measurement is particularly critical for performance evaluation of thermoelectric materials, but the experiments by differential scanning calorimetry (DSC) often lead to large uncertainties in the measurements, especially at elevated temperatures. In this study, we propose a simple method to determine Cp by measuring the sound velocity (υ) based on lattice vibration and expansion theory. The relative standard error of the υ is smaller than 1%, showing good accuracy and repeatability. The calculated Cp at elevated temperature (>300 K) increases slightly with increasing temperature due to the lattice expansion, which is more reasonable than the Dulong–Petit value. [ABSTRACT FROM AUTHOR]

Properties of strange quark matter (SQM) have been studied as diquark matter with diquark correlation. The dense SQM is under strong magnetic field due to electroweak interaction of quarks. Here it is suggested that u, d, s quarks get correlated to form diquark matter of different flavors. The diquarks are suggested to behave like quasiparticles under the influence of strong magnetic field inside the dense quark matter. In the current work diquarks are described as the composite fermions which behave like quasiparticle under the strong magneticfield in an analogy with the electrons behaving in strong magnetic field. The thermodynamic potential for SQM has been estimated and behavior is studied with respect to chemical potential. The equation of state and the velocity of sound through SQM are also studied. Some interesting observations are made. It is suggested that the composite fermion picture of diquark correlation lowers the binding energy of the system making the SQM a more stable state. [ABSTRACT FROM AUTHOR]

The micellar properties of octyltrimethylammonium bromide (C 8 TAB) in both water and aqueous solutions of 1,2-propanediol have been investigated using accurate measurements of density, sound velocity, and surface tension in the temperature range between 293.15 and 308.15 K. The critical micelle concentration, CMC, the ionization degree, β , the standard thermodynamic parameters of micellization: free energy, Δ mic G °, enthalpy, Δ mic H °, entropy, Δ mic S ° and the free energy of transfer, Δ tr G °, of the surfactant octyltrimethylammonium bromide in both water and 1,2 propanediol aqueous solution were evaluated from the experimental results. The CMC of the surfactant increases as the concentration of 1,2-propanediol increases, while the temperature does not exert important changes within the range considered. The value of the micellization thermodynamic parameters suggests that adding 1,2-propanediol makes the micellization process less favorable. The thermodynamic functions of transfer were calculated. The values of the free energy of transfer are small and positive and increase as the diol concentration increases confirming that the transfer of the surfactant from the bulk into the micelle is less favorable. [ABSTRACT FROM AUTHOR]

The acoustic properties of seafloor sediments have always been important parameters in sound field analyses and exploration for marine resources, and the accurate acquisition of the acoustic properties of sediments is one of the difficulties in the study of underwater acoustics. In this study, sediment cores were taken from the northern South China Sea, and the acoustic properties were analyzed. Since traditional methods (such as regression equations or theoretical models) are difficult to apply in practical engineering applications, we applied remote sensing data to sound velocity prediction models for the first time. Based on the influencing mechanism of the acoustic properties of seafloor sediments, the sediments’ source, type and physical properties have a great influence on the acoustic properties. Therefore, we replaced these influencing factors with easily accessible data and remote sensing data, such as parameters of granularity, distance to the nearest coast, decadal average sea surface productivity, water depth, etc., using deep neural networks (DNN) to develop a sound velocity prediction model. Compared with traditional mathematical analyses, the DNN model improved the accuracy of prediction and can be applied to practical engineering applications.

Abstract The bulk carrier excitation influences the phonon dynamics, which can alter and modulate the surface charge density of topological insulators such as bismuth selenide (Bi2Se3). This work investigates the charge carrier and phonon dynamics in Bi2Se3 grown on various substrates. The orientation of the substrate, the size of the crystallites, and the misfit of the lattice affect the carrier and phonon dynamics. Bi2Se3 thin films are grown under the same growth conditions on SiO2, Si(111), and SiN. Bi2Se3 overlayers exhibit substrate‐dependent charge carrier relaxation channels and phonon dynamics. It is evident from Raman spectroscopy and ultrafast transient absorption spectroscopy that the heterointerface interactions of all three samples affect the vibration modes of Bi2Se3 and coherent acoustic phonon oscillations in the NIR range. At 13.6, 41.2, and 34.4 GHz, the vibration modes of SiO2, Si(111), and SiN are equivalent. The propagation depth of phonon waves is shown by measuring the speed of sound in Bi2Se3 overlayers on SiO2, Si(111), and SiN. This study demonstrates that the surface and bulk‐bound charge carriers of a topological insulator determine the frequency and velocity of the generated sound.

Abstract Isobaric specific heat capacity (Cp) is an important parameter not only in physics but also for most materials. Its accurate measurement is particularly critical for performance evaluation of thermoelectric materials, but the experiments by differential scanning calorimetry (DSC) often lead to large uncertainties in the measurements, especially at elevated temperatures. In this study, we propose a simple method to determine Cp by measuring the sound velocity (υ) based on lattice vibration and expansion theory. The relative standard error of the υ is smaller than 1%, showing good accuracy and repeatability. The calculated Cp at elevated temperature (>300 K) increases slightly with increasing temperature due to the lattice expansion, which is more reasonable than the Dulong–Petit value.

The salinity of seawater is of fundamental importance in climate studies, and the measurement of the variable requires high accuracy and precision in order to be able to resolve its typically small variations in the oceans with depth and over long-time scales. This is currently only possible through the measurement of conductivity, which has led to the definition of a Practical Salinity scale. However, seawater is also composed of a large number of non-conducting substances that constitute salinity anomalies. Differences of the ratios of the constituents of sea salt from the Reference Composition may also change salinity anomalies. The establishment of formulae for calculating the thermodynamic properties of seawater has led to the definition of the concept of Absolute Salinity (SA), which includes such anomalies and is similar in approach to the notion of density. Although the routine in situ measurement of SA is still a huge challenge, numerous developments based on acoustic techniques, but above all, refractometry, interferometry or complex fiber optic assemblies, have been tested for this purpose. The development of monolithic components has also been initiated. The measurement of the refractive index by these techniques has the advantage of taking into account all the dissolved substances in seawater. This paper reviews the difficulties encountered in establishing theoretical or empirical relations between SA and the sound velocity, the refractive index or the density, and discusses the latest and most promising developments in SA measurement with a particular focus on in situ applications.

Multicomponent lipid bilayers are used as models for searching the origin of spatial heterogeneities in biomembranes called lipid rafts, implying the coexistence of domains of different phases and compositions within the lipid bilayer. The spatial organization of multicomponent lipid bilayers on a scale of a hundred nanometers remains unknown. Brillouin spectroscopy providing information about the acoustic phonons with the wavelength of several hundred nanometers has an unexplored potential for this problem. Here, we applied Brillouin spectroscopy for three binary bilayers composed of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), 1,2-palmitoyl-sn-glycero-3-phosphocholine (DPPC), and cholesterol. The Brillouin experiment for the oriented planar multibilayers was realized for two scattering geometries involving phonons for the lateral and normal directions of the propagation. The DPPC–DOPC mixtures known for the coexistence of the solid-ordered and liquid-disordered phases had bimodal Brillouin peaks, revealing the phase domains with sizes more than a hundred nanometers. Analysis of the Brillouin data for the binary mixtures concluded that the lateral phonons are preferable for testing the lateral homogeneity of the bilayers, while the phonons spreading across the bilayers are sensitive to the layered packing at the mesoscopic scale. Graphical Abstract [ABSTRACT FROM AUTHOR]

Hafnium carbide (HfC) and tantalum carbide (TaC), as potential ultra-high temperature ceramics (UHTCs), have attracted widespread attention due to their unique physical and chemical properties. Here, dense HfC and TaC ceramics are synthesized under high pressure and high temperature 15 GPa and 1700 °C, respectively. The sound velocities and elasticity behavior of sintered HfC and TaC under high pressure have been experimentally investigated by using ultrasonic interferometry and validated by first-principles study. The bulk and shear moduli with their pressure dependence have been determined as B 0 = 272.6(2.7) GPa, G 0 = 215.8(2.2) GPa, ∂ B / ∂ P = 3.44 (5) , and ∂ G / ∂ P = 1.74 (3) for HfC, B 0 = 355.9(3.6) GPa, G 0 = 236.6(2.4) GPa, ∂ B / ∂ P = 3.98 (5) , and ∂ G / ∂ P = 1.65 (2) for TaC. The Vickers hardness and fracture toughness of HfC and TaC are generated from empirical models. The present work provides deep insights into the engineering application of UHTCs HfC and TaC under high-pressure extreme conditions. [ABSTRACT FROM AUTHOR]

We investigated the electronic, phonon frequencies, and sound velocity of GaAs1-xNx ternary semiconductor alloys with the zinc-blende crystal structure over the entire nitrogen concentration range (with x from 0 to 1) using the empirical pseudo-potential model within the virtual crystal approximation including the compositional disorder effect. The pressure-dependent electronic, phonon frequencies and sound velocity of GaAs1-xNx ternary alloy have been studied. Our findings and the existing experimental data are found to be in good agreement. According to the dependence on pressure, a rising bandgap is predicted for GaAs1-xNx alloys at high-pressure values. According to the findings of this study, the GaAs1-xNx characteristics could have substantial optoelectronic applications in the infrared and mid-infrared spectral ranges. [ABSTRACT FROM AUTHOR]

Copyright of Advances in New & Renewable Energy is the property of Editorial Office of Advances in New & Renewable Energy 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.)

The results of experimental study of the excessive hypersound absorption in an aqueous acetone solution are discussed based on the conclusions of the theory of high-frequency sound scattering near the critical point (developed by Chaban) and the Landau theory. These results are described within the framework of the Landau and Chaban theories and explained by the existence of two different states with minimum thermodynamic stability in the solution. The main conclusions of the theory are presented, and a method for measuring the absorption coefficient of hypersound near the temperature of the unstable thermodynamic state is described. [ABSTRACT FROM AUTHOR]