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Densities, viscosities and ultrasonic velocities of binary liquid mixtures of hexylene glycol (2-methyl-2,4-pentanediol) with toluene, aniline, chlorobenzene, nitrobenzene, benzaldehyde and N,N-dimethylaniline have been measured at 308.15 and 318.15 K. From these data, excess volume (VE), deviation in isentropic compressibility (∆KS), deviation in viscosity (∆η), intermolecular free length (∆Lf), intermolecular free volume (∆Vf) and deviation in acoustic impedance (∆Z) have been calculated. FT-IR studied for appropriate mixture to conform hydrogen bonding. Thermodynamic excess properties have been correlated with the Redlich and Kister type of polynomial equation to derive the coefficients and standard errors. Variations in the calculated excess quantities have been studied for mixtures of hexylene glycol with component liquids. Intermolecular interactions have been interpreted from the obtaining experimental results. [ABSTRACT FROM AUTHOR]

The characteristics of heavy rare earth intermetallic GdCu are investigated by the theoretical evaluation of thermophysical and ultrasonic properties at different temperature and pressure. Initially, second-order elastic constants (SOECs) are determined in the temperature range 300–900 K and pressure range 0–40 GPa using the potential model approach. The elastic moduli and anisotropy factor are also estimated for elastic and mechanical characterization. Later on, ultrasonic velocity, thermal conductivity, thermal expansion coefficient and melting point of chosen compounds are calculated utilizing estimated SOECs, density and lattice parameters within the same physical conditions for the ultrasonic and thermal characterization. It is found that the bulk modulus and thermal conductivity enhance with increase in pressure while reduce with temperature. The ultrasonic velocity is found to vary linearly with temperature and non-linearly with pressure. The analysis explores that intermetallic GdCu manufactured at high pressure shall have good mechanical strength, elastic behavior and high melting point. [ABSTRACT FROM AUTHOR]

In this article, we describe the effects and the degree to which they cause error in the measurement of propagation velocity. Various effects include nonlinearity in path measurement, temperature stability and number of maxima or minima consideration. Double-distilled water was used as a sample to estimate various effects. Finally, it has been concluded that the variable frequency approach may be preferred for better accuracy. It has also been observed that the digital frequency selection is more precise than mechanical distance variation. [ABSTRACT FROM AUTHOR]

Density, viscosity and ultrasonic velocity of binary mixture of carbamide with N, N-dimethylformamide have been measured at temperatures of 10 °C, 20 °C, 30 °C and 40 °C and at atmospheric pressure. From these experimental measurements the thermoacoustical parameters such as acoustic impedance (Z), adiabatic compressibility (), relaxation time (?), intermolecular free length (Lf) and Gibb's free energy of activation (ΔG) have been calculated. The variations in these parameters have been correlated to derive the intermolecular interactions taking place between the species of present binary mixture. [ABSTRACT FROM AUTHOR]

The velocity and density of binary mixtures of diethyl malonate with formamide, dimethylformamide and dimethylacetamide were experimentally measured at temperatures (303.15, 308.15, 313.15, 318.15)K. Various acoustic and thermodynamic parameters were evaluated using experimental data, the results have been discussed based on molecular interactions and geometric effects of the components in the mixture. FT-IR spectral analysis gives evidence of molecular association. [ABSTRACT FROM AUTHOR]

The determinations of the effects of cyclic loading on the deformation failure characteristics and ultrasonic properties of granite are significant to accurate the evaluations of stability and safety of excavation damage zones. However, previous experimental studies regarding granite under cyclic loading have not achieved adequate results. This study conducted a series of cyclic tests investigating the mechanical properties and ultrasonic velocities of granite specimens. The results indicated that the stress-strain curves had presented only minimum crack growth phase and no residual strength in the post-peak phase due to the strong brittle properties of the granite. Also, the residual strain of the granite specimens under uniaxial cyclic loading-unloading compression conditions was observed to decrease with the cyclic number as a result of pre-existing crack closure. However, with triaxial cyclic loading, it was found that the residual strain had initially decreased, and then increased after several cycles. It was also was observed that the elastic strain of the granite had displayed increasing trends in both the uniaxial and triaxial cyclic loading-unloading compression experiments. The failure modes in uniaxial cyclic compression tests are known to be complicated, and more failures will be evident with increased damage to the thermoplastic membranes. After confining pressure was applied, the failure mode was determined to mainly be shear fracture and to be less serious than failures observed in the uniaxial cyclic compression tests. The P and S wave velocities showed nonlinear characteristics during the loading processes. The relationship between the dynamic Young's modulus and the static Young's modulus could be expressed as a linear function. However, the static Young's modulus was determined to be larger than the dynamic Young's modulus. In this present study, both the P and S wave velocities showed that stress related properties first increased and then decreased with the stress. [ABSTRACT FROM AUTHOR]

Densities and ultrasonic velocities were measured for the mixtures of (nitrobenzene + cyclohexane) and (N,N-dimethylformamide + cyclohexane) over the volume fraction range 0.1–1 at 298–318 K. Different derived parameters such as adiabatic compressibility, Intermolecular free length, acoustic impedance, molar volume, molar sound velocity, molar compressibility, relative association, excess volume, and excess adiabatic compressibility have been computed. The observed positive and negative values of the excess parameters for all the studied mixtures were explained based on the intermolecular interactions in these mixtures. Furthermore, different empirical relations were used to compare the binary mixture densities and ultrasonic velocities. [ABSTRACT FROM AUTHOR]

Present paper reports study of some physical properties like density, viscosity and ultrasonic study for the binary mixtures of methylethylketone and nitrobenzene over the entire concentration range were measured at temperatures 313 K. The experimental data is further used to calculate the derived properties like compressibility, and acoustic impedance, molecular free length, Inverse relaxation time and excess Parameters. The values of excess properties further fitted with Redlich–Kister polynomial equation to estimate the binary coefficients. The resulting excess functions were interpreted in terms of the interactions between the molecules in the binary mixtures. [ABSTRACT FROM AUTHOR]

The present article comprises computation of elastic, ultrasonic, and thermo-physical properties of RM (R = Tb, Dy, Ho, Er, Tm; M = Zn, Cu) compounds at 300 K. The second-order elastic constants (SOECs) and elastic moduli are evaluated initially, using potential model approach considering interaction up to second nearest neighbours. The ultrasonic velocities are obtained for wave propagation along <100>, <110>, and <111> crystallographic directions using evaluated SOECs. The Debye temperature, specific heat at constant volume, thermal energy density, thermal conductivity, and thermal relaxation time are also calculated. The obtained results are compared and analysed for justification and application of materials. [ABSTRACT FROM AUTHOR]

Ultrasonic velocities, u , and densities, ρ , of binary liquid mixtures of dimethyl sulphoxide (DMSO) with ketones such as acetophenone (AP), cyclohexanone (CH), and 3-pentanone (3P), including pure liquids, over the entire composition range have been measured at 308.15 K. Using the experimental data, deviation in ultrasonic velocity, Δ u , deviation in isentropic compressibility, Δ k s , excess molar volume, V m E , excess intermolecular free length, L f E and excess acoustic impedance, ZE , partial molar volumes, V ‾ m , 1 , V ‾ m , 2 , and excess partial molar volumes, V ‾ m , 1 E , V ‾ m , 2 E have been calculated. Molecular interactions in the systems have been studied in the light of variation of excess/deviation values of calculated properties and these properties have been fitted to Redlich–Kister type polynomial equation. The observed positive values of V m E , Δ k s , L f E and negative values of Δ u , ZE for all the binary liquid mixtures studied clearly indicate the presence of the dominance of weak physical interactions between the components of molecules. Further, FTIR spectra support the conclusions drawn from deviation/excess properties. Moreover, theoretical values of ultrasonic velocity in the mixtures have been evaluated using various theories and such values were compared with experimental velocities to verify the applicability of such theories to the systems investigated. [ABSTRACT FROM AUTHOR]

In this work, the applicability of Free Length and Collision Factor theories to predict multicomponent isentropic compressibilities is analyzed and compared. To this end, appropriate expansions for ternary mixtures were derived from the original works, and then applied to a mixture containing dislike compounds in terms of functional molecular groups. Excess molar volumes from open literature and new experimental ultrasonic velocities of the mixture acetone+methanol+n-hexane were used to compute the corresponding isentropic compressibilities. A good accuracy was obtained when ternary prediction is attempted in this partially soluble mixture at different temperatures by the Collision Factor theory. These results show the versatility of this model for estimation studies in complex multicomponent mixtures enclosing phase splitting. [ABSTRACT FROM AUTHOR]

The variation of properties of concrete with initial damage under sulfate and wet-dry-cycle environments was experimentally investigated. With increased corrosion time, changes in the parameters of concrete with initial damage were analyzed, including mass, ultrasonic velocity, compressive strength, stress-strain curves, and the activities of acoustic emission under uniaxial compression. A quantitative evaluation and parameter fitting for corrosion damage was made based on damage mechanical theory. Based on the acoustic emission characteristics, a damage model of corroded concrete with initial damage was established and its damage evolution was analyzed. Using environmental scanning electron microscopy (ESEM) and energy-dispersive X-ray analysis (EDX), the damage mechanisms were revealed in observations of the microstructures and element compositions of concretes with initial damage induced by sulfate corrosion. The research results show that with increased erosion time, the mass, ultrasonic velocity, and compressive strength of concrete with different degrees of initial damage first increase and then decrease. Increases in the degree of initial damage may accelerate the degradation of physical and mechanical properties, but a threshold effect exists. Compressive strength and ultrasonic velocity can be regarded as damage variables, and corrosion damage evolution equations and the functional relationship between different damage formulas were established. With increased erosion time, the stress-strain curve of concrete with initial damage is obviously concave-upward and the elastic-stage time period can be comparatively shorter whereas the yield-stage time period increases. An increase in the degree of initial damage results in an obvious attenuation of the acoustic emission activity, which lags behind the time of the obvious acoustic emission response. Based on the acoustic emission characteristics, the damage evolution process of concrete with initial damage can be divided into three stages, including the compaction, stable damage evolution and development, and accelerating damage development stages. With an increase in the degree of initial damage, stronger corrosion reactions and composition changes occur inside the concrete. Compared to undamaged concrete, the expansion and extension of denser and deeper micro-cracks occur in concrete with initial damage under sulfate attack, which accelerates the degradation of the physical and mechanical properties of corroded concrete.

In this study, the behavior of glass-ceramics synthesized from a glass frit of FFW (Final Flotation Waste) originated from the RTB Bor Company was investigated. Thermal shock resistance was monitored in order to assess the possibility of application of such waste material. Thermal shock of the samples was conducted using water quench test. Image analysis and ultrasonic measurements were used as nondestructive methods for quantification of thermal shock damage at the surface and in the bulk of the specimens. Phase composition of samples was determined by X-ray powder diffraction (XRPD). The degradation level of samples was about 43 % after 20 cycles of water quench tests. The results pointed out that glass-ceramic material exhibited good thermal shock resistance. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. OI176010 and Grant no. III45012]

Ultrasonic velocity measurements, density measurements and viscometric studies were conducted for the drug buspirone hydrochloride (0.01–0.1 M) at three different concentrations (0.1, 0.05 and 0.025 M) at 298.15 K/1 atm. The buspirone hydrochloride was prepared in aqueous solutions of Cu(II) and Co(II) metal ion. The experimental data were used to determine acoustical parameters, such as isentropic compressibility, intermolecular free length, specific acoustic impedance, relative association, free volume, internal pressure, viscous relaxation time, Gibb's free energy, attenuation coefficient, Rao's constant, and Wada's constant. The viscosity data were analysed using the Jones–Dole equation, and the values of the Falkenhagen coefficient A and Jones–Dole B-coefficient were calculated. The outcomes were expressed in terms of the molecular interactions and the variations in parameters under varying solute concentrations. Concluding remarks regarding intermolecular interactions are provided.

Ultrasonic velocity (U), density (ρ), viscosity (ƞ) for the ternary mixture of benzene + chloroform + cyclohexane in the whole range of composition has been carried out at various temperatures 303.15, 308.15 and 313.15K. From the measured parameters U, ρ and ƞ, some derived parameters β, Lf, Vf, πi, Z, R,W with molar enthalpy (Hm) and apparent molar volume (ɸv) are also estimated. The decreasing trend of ƞ, R,W, Hm, and ɸv with concentrations and other parameters are in increasing trend were observed. The trend of acoustical and physico-chemical parameters confirm the dynamics of molecules at higher temperature and the magnitude of intermolecular interactions among the constituents of the mixtures always reflects the nature of substance. The role of enthalpy and apparent molar volume has been used to determine their thermal response. The sign and magnitude of these properties are evident for the nature of interactions between component molecules.

Molecular interactions are evaluated in the binaries of Ethyl Lactate and Dimethyl Adipate using experimental values of density, ultrasonic velocity and refractive index over entire composition range as a function of temperature from 303.15 to 318.15 K at atmospheric pressure. Excess thermodynamic properties: excess molar volume, excess isentropic compressibility, excess isothermal compressibility, excess free length, excess isobaric thermal expansion coefficient, excess ultrasonic velocity and refractive index deviations are computed and fitted with Redlich-Kister polynomial equation to obtain the binary coefficients and the standard deviations. The existence of specific interactions in the mixture is revealed by excess properties, and further supported by partial molar properties. FTIR analysis ascertains the dominance of packing effect in the studied mixtures. Prediction of refractive index for the mixtures and pure components is done by several mixing rules with the estimation of relative errors. In addition, data are analysed by the Prigogine–Flory–Patterson theoretical model. [ABSTRACT FROM AUTHOR]

Improvement of elastic and optical properties of rare earth ions doped glasses via the amalgamation of synthetic glass formers with natural mineral modifier became a new strategy to achieve novel glass based optical devices. Inspired by this idea, we prepared some new types of CeO 2 doped boro-tellurite-dolomite (BTD) glasses of composition (35- x)B 2 O 3 –30TeO 2 -20Dp-15Dm- x CeO 2 (where 0 ≤ x ≤ 2.0 mol%, Dm: dolomite marble and Dp: dolomite pebble) by standard melt-quenching method and characterized. The role of changing CeO 2 concentration on the structural, elastic and optical traits of the proposed glasses was examined. Also, direct and indirect band gap energies, Urbach energies and refractive indices of glasses were evaluated using Tauc, absorption spectrum fitting (ASF) and derivation of absorption spectrum fitting (DASF) methods. Amorphous nature of the as-quenched samples was verified from XRD pattern and SEM image showed the homogeneous disordered surface. EDX spectra disclosed the right elemental traces in the prepared glasses. The N 4 ratio calculated from the FTIR spectra revealed that the inclusion of CeO 2 into the BTD network indeed favoured the conversion of BO 3 to BO 4 structural units. Besides, the ultrasonic velocities and elastic moduli were reduced with the increase in CeO 2 contents. Complete absence of any peak in the optical absorption spectra validated the existence of Ce4+ within glasses. Moreover, the absorption coefficient of prepared glasses was significantly enhanced and the absorption edge was red shifted (from 400 nm to 500 nm) with the increase in CeO 2 doping. Proposed glass compositions may be beneficial for future research and development on optical filter in photonic devices. [ABSTRACT FROM AUTHOR]

In this paper, the variation of the ultrasonic velocity and density, to extract other physical properties such as Viscosity, Adiabatic compressibility, Relative association, Internal free length, Acoustic impedance for the dielectric constants of Dimethyl Sulfoxide, Ethanol water, and Acetone with respect to the variation in the concentration are analysed. The comparison with experimental data in the literature has been performed. The study on the effect of the variations on the acoustical parameters in the binary mixture of DMSO, ethanol water, and acetone is also presented here. [ABSTRACT FROM AUTHOR]

The effects of thermal crack damage on the physical properties and rupture processes of andesite were investigated under triaxial deformation at room temperature. Thermal cracking was induced by slowly heating and cooling samples. The effects of heat treatment temperatures ranging between 500 °C and 1100 °C on the P-wave velocities and on the microstructure were investigated. Then, the mechanical properties of andesite samples treated at 930 °C were investigated under triaxial stress at room temperature using constant strain rate tests and confining pressures ranging between 0 and 30 MPa. Similar triaxial experiments were conducted on non-heat-treated samples. Our results show that: (1) for heat treatments at temperatures below 500 °C, no significant changes in the physical properties are observed; (2) for heat treatments in the temperature range of 500–1100 °C, crack density increases; and (3) thermal cracking has no influence on the onset of dilatancy but increases the strength of the heat-treated samples. This last result is counterintuitive, but seems to be linked with the presence of a small fraction of clay (3%) in the non-heat-treated andesite. Indeed, for heat treatment above 500 °C, some clay melting is observed and contributes to sealing the longest cracks. [ABSTRACT FROM AUTHOR]

In order to comprehensively evaluate the properties of rock-filled concrete (RFC) with the strength of C15, lab experimental test and in-situ test are applied to explore the mechanical, hydraulic, ultrasonic characteristics of RFC in Hantang reservoir dam. Four types of defects within RFC are shown from the appearance of borehole cores specimens: (1) large sized voids existing in interfacial transition zone (ITZ) between self-compacting concrete (SCC) and rock block (RB); (2) bad cohesion in ITZ; (3) joints within rock block; (4) voids within SCC. For hydraulic aspects, the average porosity of RFC is 14.10%; the permeability rate of RFC ranges from 2.41 Lu to 10.41 Lu, with the average of 11.32 Lu, occasionally more than 25.52 Lu due to interconnected defects. For ultrasonic aspects, the ultrasonic velocity of RFC conforms to lognormal distribution, with the average of 2993.3 m/s and standard deviation of 650.5 m/s. For mechanical aspects, the average cubic compressive strength of RFC is 22.55 Mpa, with the standard deviation of 4.09 Mp. Thus the data shows a relatively great dispersion due to uneven distribution of some defects in RFC, which deteriorate the quality of RFC. Through the experimental investigation, it is shown that the quality of massive RFC in the Hantang dam is obviously non-homogeneous, mainly influenced by construction technology. [ABSTRACT FROM AUTHOR]

A suite of hydrostatic compression tests in a St Peter sandstone core was performed to characterize its static and dynamic poroelastic response. The pore pressure cycles under constant confining pressure simulated scenarios of reservoir depletion and injection. The volumetric deformation and axial ultrasonic velocities (Vp and Vs) were recorded and the corresponding effective stress coefficients were derived. As expected, the variations of pore pressure under constant confining pressure induce poroelastic deformation and velocity changes, which is generally consistent with the exact effective stress law. Data discrepancy between depletion and injection was observed throughout the cycles, which is considered to be a result of material hysteresis. The dynamic elastic moduli were calculated based on the velocities by assuming isotropy, which are in qualitative agreement with the static values. The static and dynamic effective stress coefficients were derived with respect to volumetric deformation and Vp and Vs. It is found that the static effective stress coefficient is consistently less than unity, and decreases from an average of ~ 0.6 with pressure difference to as low as ~ 0.35. The pore pressure has a measurable positive influence on the coefficient for the same pressure difference. The dynamic effective stress coefficient is generally around unity when the pressure difference is low (< 30 MPa), but deviates significantly from unity as the pressure difference further increases. The trend of such deviation highly depends on the wave type and loading path. Despite possible experimental artifacts, the derived dynamic effective stress coefficient is quite distinct from the static counterpart. This corroborates previous findings that the effective stress coefficients of different physical quantities are fundamentally different. It emphasizes that the estimation of static effective stress coefficient based on correlation with dynamic data is not fully warranted and can incur significant errors. [ABSTRACT FROM AUTHOR]

The work presented in this paper deals with the study of thermodynamic properties of new working fluids for absorption machines, mainly for characterisation of absorbent–refrigerant pairs that could improve the cycle performance. The study of atomic motion in liquids plays an important role in understanding the solid-like behaviour of liquids. The accurate measurement of the energy changes due to scattering can be used to study the dynamical behaviour of liquids. Measurements of the ultrasonic velocity (u), density (ρ) and viscosity (η) for binary mixtures of polyethylene glycol 250 dimethyl ether with 1-propanol and 1-butanol have been made at three temperatures (T = 293, 303 and 313 K) over the entire composition range in order to investigate the nature of intermolecular interactions between the components of these liquid mixtures. Non-linear variation of derived quantities with the mole fraction supports the molecular interaction occurring between component molecules. [ABSTRACT FROM AUTHOR]

Study on the weathering characteristics of Niche of Sakyamuni Entering Nirvana at Dazu Rock Carvings is the first step of scientific conservation. Based on the in-depth investigation on the weathering characteristics of Niche of Sakyamuni Entering Nirvana, the weathering degree was measured and evaluated by means of the in-situ non-destructive surface hardness test and ultrasonic test. The results reveal that the weathering types of Niche of Sakyamuni Entering Nirvana consist of granular disintegration, salt efflorescence, scaling, blistering, cracking, missing parts, biological colonization, and water seepage. The weathering degree of the head and foot of the statues are higher than that of the chest and abdomen in the horizontal direction, and the weathering degree of the upper parts of the statues and the ground area are higher than that between them in the vertical direction. The results of surface hardness and ultrasonic velocity are in close accordance with the weathering degree of the statues. Sedimentary and structural characteristics of sandstone lay a material foundation for various weathering characteristics and degree. The research results pave the way for condition assessment, intervention decision-making, and preventative conservation of the studied statues. [ABSTRACT FROM AUTHOR]

• Thermal cycling effect of LCO 2 cyclic injection on crack evolution was studied. • The relations among velocity, coal rank and injection cycles were studied. • The velocity ratio method was proposed to study the spatial variation of cracks. • A tridirectional velocity test method was developed to study velocity anisotropy. Enhanced coalbed methane (CBM) recovery by injecting liquid CO 2 (LCO 2) has been a promising research topic for decades. Although the phase-fracturing and blooding effect during injection have been studied, the non-isothermal impact of cryogenic fluids on the coal matrix, especially the effect of thermal cycling generated by the cyclic LCO 2 injection process, has not been studied in detail. This paper reports the development of a high-pressure and low-temperature reaction system, which can simulate the effect of thermal cycling on three different coals of different ranks, and the use of an ultrasonic device to study the P-wave velocity (Vp) in different directions before and after the influencing thermal cycling. The results show that all the cores subjected to different thermal cycling fractured to diverse degrees due to their initial texture and rank, and more cycles and lower rank increased the final fracture results. Influenced by thermal cycling, two endpoints of the Vp confidence interval (confidence level of 95%) of the coals decreased, and the velocity range of confidence interval all increased, the change of which might be attribute to the rank and the companying thermal cycling effect, resulting in the changes of crack structure and discrete degree of the velocity. The velocity anisotropy coefficient (k) value of the coal increased as the cycles increased, indicating that thermal cycling alters the coal structure randomly by means of fatigue accumulation and grain bond deterioration. The Vp z /Vp x and Vp z /Vp y value changes indicated that the internal cracks were not generated uniformly in all directions, and the presence of cracks helped the transfer of heat flux, which caused some thermal stress concentration areas to occur, further facilitating crack propagation at the crack tips. Meanwhile, the ΔVp% scatters of lignite, bituminite and anthracite cores were fitted as exponential, DoseResp and linear curves with cycles, respectively (R2 > 0.94). The mean fractal dimension D of the coals all increased with increasing cycles, and were negatively correlated with coal rank and ΔVp%, and positively correlated with Δk. The results provide some useful theoretical guidance for field application. [ABSTRACT FROM AUTHOR]

The research on several properties of erbium-doped zinc tellurite glass system is thoroughly investigated recently. However, the introduction of silver oxide as a dopant plays a role on the fabrication of new optical materials specifically in optical application. By conducting the investigation, the use of melt-quenching technique is one of the techniques to fabricate a series of silver-doped zinc tellurite glass systems with the chemical composition of [[(TeO2)0.7(ZnO) 0.3] 0.96 (Er2O3)0.04]] 1-x (Ag2O) x at different molar fraction of x = 0.01, 0.02, 0.03, 0.04 and 0.05. The characterization of X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, density, elastic and optical measurements were investigated to analyse the prepared glass samples. The result of the XRD, FTIR, density, elastic and optical properties were all reported at the room temperature. The glass samples are proven as amorphous in nature which can be seen by the XRD spectra. Besides that, the presence of functional vibration of tellurite network can be clearly observed through the analysis of FTIR spectra. The density of the glass system is found to increase with the increase of silver oxide concentration. Anyhow, the value of molar volume is noticed to be inversely proportional to the density. Therefore, the inclination in the density value causes the decrement of the molar volume which can be associated with the inclusion of silver oxide in the glass system. Plus, this also follows the theoretical formula where the density is equivalent to molar mass per molar volume. In the meantime, the ultrasonic velocity was employed in order to specify the elastic moduli of the glass systems. The elastic moduli for instance longitudinal modulus, shear modulus, bulk modulus, Young's modulus as well as other parameters come out with a varying trend against the concentration of silver oxide. The increment of the elastic moduli can be attributed to the high connectivity and rigidity of the glass structure. Nonetheless, the decrement of the elastic moduli can be associated with the breakage of bonds within the zinc tellurite glass system which impair the structure of the glass sample. The UV-Vis analysis can determine the optical properties of the prepared glass samples. The optical absorption was reported at room temperature within the wavelength ranging from 200 to 2000 nm. The optical absorption spectra unveil the fundamental absorption edge shifts to longer wavelength as the content of silver oxide increases. The values of direct and indirect band gap and metallization criterion have been evaluated and noticed to have a decreasing trend with the increasing content of silver oxide whereas the Urbach energy, refractive index, molar refraction, molar polarizability, oxide ion polarizability and optical basicity are obviously increasing as the concentration is included into the glass system. [ABSTRACT FROM AUTHOR]

Densities, viscosities and ultrasonic velocities of p-anisaldehyde – methyl acetate mixtures have been measured over the entire mole fractions at 308.15, 318.15, and 328.15 K and at 0.1 MPa. The excess molar volume, viscosity deviations and ultrasonic velocity deviations have been calculated. The new equations have been developed for excess molar volume, viscosity deviations, and ultrasonic velocity calculations using statistical software Design Expert. The excess thermo physical properties were fitted to Redlich–Kister model, Hind model, and Grunberg–Nissan model to obtain their coefficients and standard deviations using DATAFIT software. [ABSTRACT FROM AUTHOR]

Ultrasonic velocity technique has been employed to estimate the critical micellar concentration (CMC), solute-solvent interactions, compressibility behavior and ultrasonic allied parameters of Terbium octanoate in mixed organic solvent at four different temperatures i.e. 25, 30, 35 and 40oC. The results have revealed that value of CMC increase with elevating temperature and there exist significant interactions between terbium octanoate and solvent molecules after micellization. [ABSTRACT FROM AUTHOR]

Abstract Multiwalled carbon nanotubes (MWCNTs) has been synthesized using chemical vapor deposition (CVD) method. Al – Layered Hydroxide (Al–LH) and MWCNTs nanocomposites; (1- x) Al–LH + (x) MWCNTs, 0.0 ≤ x ≤ 1; have been synthesized using citrate nitrate assisted hydrothermal technique. The crystal structure and the functional groups of the prepared samples were examined using X-ray diffraction (XRD) and Infrared spectroscopy (FTIR) respectively. The layered structure seemed under the high-resolution transmission electron microscopy (HRTEM), and the morphology was observed using field emission scanning electron microscopy (FESEM). Moreover, the synthesized nanocomposites were further characterized using Zeta potential, size analysis and Brunauer– Emmett–Teller (BET) surface area which showed their different characteristics as the MWCNTs content is changed. Thermal gravimetric analysis assured the thermal stability of the nanocomposites over the temperature from room up to 480 °C depending on the MWCNTs content. The obtained results revealed the improvement of all mechanical properties with the increase of MWCNTs content. Graphical abstract FESEM of nanocomposite with 5% MWCNT together with the compositional dependence of the Young and bulk modulus. Image 1 Highlights • Layered hydroxides/MWCNTs nanocomposites were successfully prepared by sonochemical method. • The largest surface area was achieved at 2.5 wt% MWCNTs. • Better thermal stability with increasing MWCNTs concentration were achieved at x = 5 and 7.5 wt%. • Improved young and bulk modulus were remarked at 2.5 wt%. [ABSTRACT FROM AUTHOR]

Radial and axial variations in the longitudinal ultrasonic wave velocity within stem of 17–19-year-old Melia azedarach planted in two different sites in northern Vietnam were experimentally investigated. Wood samples were collected from 10, 50, and 90% of the radial length from pith at 0.3, 1.3, 3.3, 5.3, and 7.3 m heights above the ground to measure ultrasonic velocity (Vu), fiber length (FL), air-dry density (AD), and compressive strength (CS) at moisture content approximately 12%. The average wave velocity for two sites exhibited minimum value near the pith about 3700 m/s. It kept increasing to 4200 m/s at the middle position before remaining constant value forward to outside. In axial direction, the variation of Vu with height was very small and without statistical significance. Vu had a strong positive linear relationship with both FL (r = 0.69, p < 0.001) and AD (r = 0.67, p < 0.001). These findings reveal that the FL and AD greatly influence the within-tree variations in the ultrasonic wave velocity in M. azedarach. Besides, the significant positive linear correlation between CS and Vu suggests that Vu was a useful predictor of the CS for M. azedarach planted in northern Vietnam. [ABSTRACT FROM AUTHOR]

The acoustic emission (AE), ultrasonic velocity and stress-strain behaviors of brittle rocks containing natural fractures were simultaneously measured under uniaxial compression. An optimized sparse network of transducers was used to monitor the crack-induced AE activities and changes of velocities in different directions. The variation of rock anisotropy was co-characterized by wave velocity and localization of AE hypocenters. The microscale behaviors of rock failure were investigated by the analysis of AE waveforms and multiple characteristic parameters. A flurry of AEs behaving at low frequency and low amplitude appear even under a low stress level for fractured rocks. With an increase of stress, the initiation of cracks first occurs along the natural fracture accompany with increased dominant frequency, then decreases rapidly after the coalescence of cracks. The natural fracture is the main source of rock anisotropy, which decreases first as the pressure-induced closure of fracture, then increases with the opening of cracks along the fracture. For rocks with a higher inclined fracture, the anisotropy parameter is more sensitive to the initiation, propagation and coalescence of cracks. Unexpectedly, the increase of AEs occurs much earlier than the inflection of velocity, and AE hypocenters based on the time-variable velocity depicts the localization and propagation of cracks well. AE energy increases precipitously after 98% peak strength, accompanied with the sharp increase in the ratio of low-frequency AEs, which is a perfect precursor of potentially unstable nucleation. [ABSTRACT FROM AUTHOR]

The theoretical ultrasonic velocity in any micro/nano fluids is computed in connection with the literatures. Kudriatsav theory (KT), Jouyban–Acree model (JAM), Floty theory (FT), Ramasamy–Anbanantham model (RAM), Glinkski model (GM), McAllister model (Mc-AM), time average model (TAM), Tavlorides groups (TG), Urick model (UM), Kuster and Toksoz model and modified Urick model (MUM) methods are computed. Further the validity of those theory to identify or check or confirm the possibility of existence of type of interaction, ideal and non-ideal behavior of the system was explained in the basis of hydrogen bonding interaction, induced dipoles interactions. The values have been computed for the pure solute and solvent with the binary, ternary, and pentenary mixtures above the marginal range of miscibility at various temperatures. The models/theory is relevant to the type of fluids and the medium such as ionic, electronic, micelle, aqueous or any type of liquids. The structure breaks the bonds in the associated molecules into their components by means of temperature. The measured parameters are fitted with their polynomial relations to compute the coefficients and standard errors for the validation of the experimental results. McAllister three bodies and multibody models were used to correlate their properties at various temperatures showing association/disassociation nature. [ABSTRACT FROM AUTHOR]

Abstract Calcium carbonate whisker (CW) can reinforce the flexural strength of cement paste and limit the development of micro-cracks at ambient temperature (25 ± 2 °C), but the effect of CW on mechanical properties of cement paste after exposure to high temperatures is still unknown. Therefore, mechanical properties, i.e. flexural strength, compressive strength and splitting tensile strength were measured using CW reinforced cement specimens before and after they were exposed to high temperatures. In addition, performance of CW reinforced cement paste after exposure to high temperatures was studied by ultrasonic test and mass loss test. At last, microstructural analysis (differential thermogravimetric analysis and scanning electron microscopy) were employed to study the deterioration mechanism of temperature and reinforcement mechanism of CW. These experimental results suggested that CW played a significant role in hindering the development of cracks before 600 °C. When temperatures increased up to 200 °C, the flexural strength decreased. However, the compressive strength and splitting tensile increased. When temperatures varied from 200 °C to 400 °C, the three strengths reacted differently to the elevated temperatures. Subsequently, the residual strength rapidly decreased up to 1000 °C. After that, the three strengths increased slightly. The residual strength, ultrasonic velocity and mass loss were related to the temperatures and CW content and quantitative measurement of these factors was also discussed. [ABSTRACT FROM AUTHOR]

• A new technique was developed for reproducible ultrasonic velocities measurements. • The microstructure of composite YBCO/Ni affects notably its mechanical properties. • Voids growing among YBCO grains influence the values of the ultrasonic velocities. • V S is much more sensitive than V L to connectivity among YBCO grains. • Calculations of ϴ D showed the effective role of Ni on the YBCO lattice vibrations. A series of superconducting composites (100-x) YBa 2 Cu 3 O 7-δ + x Ni metal (x = 0, 1, 2.5, 5, 7.5, 10 and 15 wt.%) was prepared by the solid state reaction method. Density and molar volume were determined using the immersion method. X-Rays-Diffraction (XRD) and Scanning Electron Microscope (SEM) characterizations were terminated for structural and microstructural analysis. The results showed the presence of orthorhombic peaks of YBa 2 Cu 3 O 7-δ (YBCO) in the whole composite samples with different lattice constants and how Ni addition affects the distortions in the orthorhombic unit cell of YBCO. A new technique has been used to measure the ultrasonic wave velocities, longitudinal (V L) and transverse or shear (V S), at 4 MHz ultrasonic frequency at room temperature. The mechanical parameters of the sintered superconductor samples including longitudinal modulus (L), shear modulus (G), Young's modulus (Y), Poisson's ratio (σ) and microhardness (H) were investigated from the view point of the porosity and the connectivity between the formed phases. Besides, the Debye temperature (ϴ D) was also determined as a function of Ni additions. The elastic moduli, H and ϴ D have been improved up to 2.5 wt.% Ni, then a decrease in all data observed with further addition of Ni content. Quantitative analysis has been implemented to obtain more details about the structure of the composite samples, based on orthorhombic phases, the oriented grain size, the porosity and the agglomeration between grains. [ABSTRACT FROM AUTHOR]

Ultrasonic velocity of the piezoelectric ceramic pellets of ferroelectric material Na1-xKxTaO3 (X=0, 0.2, 0.3, 0.4, 0.5, 0.6 and 1.0) have been investigated at temperature 32 ºC and frequency 5 MHz with the help of ultrasonic c-scan system developed at NPL, New Delhi. The samples have been prepared by the conventional solid-state reaction method and sintering process. [ABSTRACT FROM AUTHOR]

Experimental investigations have been performed to synthesize copper oxide nanoparticles by conventional chemical precipitation method and nanofluids were prepared by two-step method using CuO nanoparticles in different proportions of ethylene glycol–water mixtures (EG–water). Powder X-ray diffraction (PXRD), energy dispersive X-ray (EDX), scanning electron microscope (SEM), particle size, and zeta potential analysis have been studied to characterize both solid and fluid samples for their sizes, shapes, stability, and arrangement. Besides, acoustics and rheological properties such as ultrasonic velocity, density, and viscosity have been measured for all fluid samples at three different temperatures. Interpretations of all these parameters have been made on the basis of particle stability and dispersion capacity of nanoparticles in different proportions of base fluids. The variation of dynamic viscosity with shear rate shows the nanofluids to be behaved like non-Newtonian fluids at very less shear rate but shows Newtonian behavior as the shear rate increases. [ABSTRACT FROM AUTHOR]