Articles de revues : « Relaxation time in fluid binary mixtures »

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HARBOLA, UPENDRA, et SHANKAR P. DAS. « SECONDARY RELAXATION IN A SUPERCOOLED BINARY MIXTURE ». International Journal of Modern Physics B 17, n^o 12 (10 mai 2003) : 2395–415. http://dx.doi.org/10.1142/s0217979203018260.

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We investigate the structural relaxation in a binary fluid over the time scales of β-relaxation regime. For this we have used a recently proposed self-consistent mode-coupling theory (MCT) formulated from the fluctuating nonlinear hydrodynamics approach. We have considered here both the hard sphere as well as the Kob–Andersen Lennard–Jones1 binary mixtures. From the solution of the MCT equations obtained here the initial power law decay t-a appears to be very weak. For the later part of the β-relaxation regime, the density correlation functions follow von Schweidler (VS) power law decay tb. The validity of the so-called factorization property of the MCT over the β-relaxation is also analyzed. We find the exponent b to be in qualitative agreement with the findings from the computer simulations of the same system by Kob and Andersen.

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Yang, Kang, et Zhaoli Guo. « Multiple-relaxation-time lattice Boltzmann model for binary mixtures of nonideal fluids based on the Enskog kinetic theory ». Science Bulletin 60, n^o 6 (mars 2015) : 634–47. http://dx.doi.org/10.1007/s11434-015-0752-9.

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Slavko, Bohdan, Mikhail Prokopenko et Kirill S. Glavatskiy. « Diffusive Resettlement : Irreversible Urban Transitions in Closed Systems ». Entropy 23, n^o 1 (2 janvier 2021) : 66. http://dx.doi.org/10.3390/e23010066.

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We propose a non-equilibrium framework for modelling the evolution of cities, which describes intra-urban migration as an irreversible diffusive process. We validate this framework using the actual migration data for the Australian capital cities. With respect to the residential relocation, the population is shown to be composed of two distinct groups, exhibiting different relocation frequencies. In the context of the developed framework, these groups can be interpreted as two components of a binary fluid mixture, each with its own diffusive relaxation time. Using this approach, we obtain long-term predictions of the cities’ spatial structures, which define their equilibrium population distribution.

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Markarian, S. A., A. S. Galstian et M. Stockhausen. « A Dielectric Relaxation Study of Diethylsulfoxide/ Tetrachloromethane Binary Mixtures ». Zeitschrift für Naturforschung A 56, n^o 11 (1 novembre 2001) : 785–87. http://dx.doi.org/10.1515/zna-2001-1116.

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Abstract The dielectric spectra of diethylsulfoxide (DESO)/tetrachloromethane mixtures have been measured from 0.5 to 72 GHz at 20 °C. On the basis of the relation between the relaxation time and the DESO concentration a complex formation between DESO and tetrachloromethane is suggested.

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Kumar, Raman, Vir Singh Rangra, Dhani Ram Sharma, Nagesh Thakur et Nainjeet Singh Negi. « Dielectric Relaxation Studies of Mixtures of N-Methylacetamide and Ethanol in Benzene Solutions Using Microwave Absorption Technique ». Zeitschrift für Naturforschung A 62, n^o 3-4 (1 avril 2007) : 213–17. http://dx.doi.org/10.1515/zna-2007-3-415.

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Using standard standing wave microwave X-band techniques, and by following Gopala Krishna’s single frequency (9.90 GHz) concentration variational method, the dielectric relaxation times (τ) and dipole moments (μ) of binary mixtures of different molar concentrations of ethanol (EtOH) in binary mixtures of N-methylacetamide (NMA) and ethanol in benzene solutions at 25, 30, 35 and 40 ◦C have been calculated. The activation parameters (ΔHε , ΔFε , ΔSε ) for the dielectric relaxation process of binary mixtures containing 30 mol% of EtOH have been calculated at 25, 30, 35 and 40 ◦C and compared with the corresponding viscosity parameters. A good agreement between the free energy of activation from these two sets of values shows that the dielectric relaxation process, like the viscous flow, can be treated as a rate process. From relaxation time behaviour of NMA and EtOH binary mixtures in benzene solution, solute-solute and solute-solvent types of the molecular association have been predicted.

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Swami, M. B., P. G. Hudge et V. P. Pawar. « Dielectric properties of benzylamine in 1,2,6-hexanetriol mixture using time domain reflectometry technique ». Journal of Advanced Dielectrics 06, n^o 04 (décembre 2016) : 1650034. http://dx.doi.org/10.1142/s2010135x1650034x.

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The dielectric properties of binary mixtures of benzylamine-1,2,6-hexantriol mixtures at different volume fractions of 1,2,6-hexanetriol have been measured using Time Domain Reflectometry (TDR) technique in the frequency range of 10 MHz to 30 GHz. Complex permittivity spectra were fitted using Havriliak–Negami equation. By using least square fit method the dielectric parameters such as static dielectric constant ([Formula: see text]), dielectric constant at high frequency ([Formula: see text]), relaxation time [Formula: see text] (ps) and relaxation distribution parameter ([Formula: see text]) were extracted from complex permittivity spectra at 25[Formula: see text]C. The intramolecular interaction of different molecules has been discussed using the Kirkwood correlation factor, Bruggeman factor. The Kirkwood correlation factor ([Formula: see text]) and effective Kirkwood correlation factor ([Formula: see text]) indicate the dipole ordering of the binary mixtures.

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de Schepper, Ignatz, et Wouter Montfrooij. « Kinetic equilibrium time-correlation functions in binary hard-sphere-fluid mixtures ». Physical Review A 39, n^o 11 (1 juin 1989) : 5807–11. http://dx.doi.org/10.1103/physreva.39.5807.

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Kumar, Rajesh, et Nagesh Thakur. « Dielectric Relaxation Studies of Binary Mixtures of N-Methylformamide and Tetramethylurea in Benzene Using Microwave Absorption Data ». Zeitschrift für Naturforschung A 63, n^o 3-4 (1 avril 2008) : 230–36. http://dx.doi.org/10.1515/zna-2008-3-419.

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The dielectric relaxation time (τ ) and dipole moment (μ) of binary mixtures of different molar concentrations of N-methylformamide (NMF) in binary mixtures of NMF and tetramethylurea (TMU) in benzene have been calculated at 25, 30, 35 and 40 ◦C using standard standing wave microwave techniques and following the single frequency (9.885 GHz) concentration variational method of Gopala Krishna. The energy parameters (ΔHε , ΔFε , ΔSε ) for the dielectric relaxation process of binary mixtures containing 30 mol% of NMF have been calculated at different temperatures, and comparison has been made with the corresponding energy parameters (ΔHη , ΔFη , ΔSη ) for the viscous flow process. Based on these studies, it was inferred that the dielectric relaxation process can be treated as a rate process just like the viscous flow process. Solute-solvent and solute-solute molecular associations have been proposed.

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Maxim, P., R. Brinkmann, C. A. Paulick, M. Elwenspoek, M. v. Hartrott, M. Kiehl et D. Quitmann. « Nuclear Quadrupolar Relaxation m Liquid Alloys and Nearest Neighbour Dynamics ». Zeitschrift für Naturforschung A 41, n^o 1-2 (1 février 1986) : 118–21. http://dx.doi.org/10.1515/zna-1986-1-217.

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A theory of the quadrupolar relaxation rate,RQ , for ideal liquid binary metallic mixtures ispresented. The theory predicts cancellation after a few tenths of a picosecond of the two andthree particle correlation terms in the fluctuation of the electric field gradient (EFG) for puremetals, and prevailing of the three particle term for binary mixtures. This is due to the highsymmetry in the arrangement of the atoms around a probe nucleus. The prevailing of the threeparticle term in binary systems leads to a longer correlation time (a few picoseconds) of thefluctuating EFG and explains the experimentally observed higher values of RQ and theirquadratic concentration dependence. The validity of the theory has been confirmed by experimentaldata. Deviations for some real systems are discussed.

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Sharma, Vimal, et Nagesh Thakur. « Molecular Association of Tetramethylurea and Chlorobenzene Molecules in Microwave Frequency Range ». Zeitschrift für Naturforschung A 65, n^o 10 (1 octobre 2010) : 854–58. http://dx.doi.org/10.1515/zna-2010-1012.

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The dielectric constant ε´ and dielectric loss ε´´ of the binary mixtures of tetramethylurea (TMU) and chlorobenzene (CB) have been calculated at 9.883 GHz by using standard standing microwave techniques. Gopalakrishna’s single frequency concentration variation method has been used to calculate dipole moment μ and dielectric relaxation time τ for different mole fractions of TMU in the binary mixture at different temperatures of 25 °C, 30 °C, 35 °C, and 40 °C. The variation of dielectric relaxation time with the mole fraction of TMU in the whole concentration range of the binary mixtures was found to be non-monotonic. The solute-solute and solute-solvent type of molecular associations may be proposed based upon above observations. Using Eyring rate equations the energy parameters ΔH, ΔF, and ΔS for the dielectric relaxation process and the viscous flow process have been calculated at the given temperatures. It is found from the comparison of energy parameters that, just like the viscous flow process, the dielectric relaxation process can also be treated as a rate process.

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Mukherjee, Arnab, Goundla Srinivas et Biman Bagchi. « Reentrant Behavior of Relaxation Time with Viscosity at Varying Composition in Binary Mixtures ». Physical Review Letters 86, n^o 26 (juin 2001) : 5926–29. http://dx.doi.org/10.1103/physrevlett.86.5926.

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Sharma, Vimal, et Nagesh Thakur. « Dielectric Relaxation Studies of Binary Mixtures of Ethanol and Chlorobenzene in Benzene Solution from Microwave Absorption Data ». Zeitschrift für Naturforschung A 63, n^o 1-2 (1 février 2008) : 93–97. http://dx.doi.org/10.1515/zna-2008-1-216.

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Dielectric relaxation of different molar concentrations of ethanol (C2H5OH) in binary mixtures of ethanol and chlorobenzene in benzene solutions has been studied at 9.883 GHz by using standard standing microwave techniques and Gopala Krishna’s single frequency concentration variation method at different temperatures (25 °C, 30 °C, 35 °C, and 40 °C). It was found that the dielectric relaxation time varies linearly with variation in the molar concentration of ethanol in the whole concentration range of the binary mixture. Based upon these results the absence of solute-solute and the presence of solute-solvent type of molecular associations could be assumed. The energy parameters for the dielectric relaxation process of binary mixtures containing 50 mol% of ethanol have been calculated at the given temperatures. Comparison has been made with the corresponding energy parameters for viscous flow processes. It was found that the dielectric relaxation process can be treated as the rate process like the viscous flow process.

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Jeevanandham, P., S. Kumar, P. Periyasamy et A. C. Kumbharkhane. « Dielectric Relaxation Studies of 2-Butoxyethanol with Aniline and Substituted Anilines Using Time Domain Reflectometry ». Advances in Physical Chemistry 2014 (18 février 2014) : 1–9. http://dx.doi.org/10.1155/2014/659531.

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The complex dielectric spectra of 2-butoxyethanol with aniline and substituted anilines like aniline, o-chloroaniline, m-chloroaniline, o-anisidine and m-anisidine binary mixtures in the composition of different volumes of percent (0%, 25%, 50%, 75%, and 100%) have been measured as a function of frequency between 10 MHz and 30 GHz at 298.15 K. The dielectric parameters like static dielectric constant ε0 and relaxation time τ have been obtained by using least square fit method. By using these parameters ε0,τ, effective Kirkwood correlation factor geff, corrective Kirkwood correlation factor gf, Bruggeman factor fB, excess dielectric constant εE, and excess inverse relaxation time 1/τE values are calculated and discussed to yield information on the dipolar alignment and molecular rotation of the binary liquid mixtures. From all the derived dielectric parameters, molecular interactions are interpreted through hydrogen bonding.

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BERGEON, A., D. HENRY, H. BENHADID et L. S. TUCKERMAN. « Marangoni convection in binary mixtures with Soret effect ». Journal of Fluid Mechanics 375 (25 novembre 1998) : 143–77. http://dx.doi.org/10.1017/s0022112098002614.

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Marangoni convection in a differentially heated binary mixture is studied numerically by continuation. The fluid is subject to the Soret effect and is contained in a two-dimensional small-aspect-ratio rectangular cavity with one undeformable free surface. Either or both of the temperature and concentration gradients may be destabilizing; all three possibilities are considered. A spectral-element time-stepping code is adapted to calculate bifurcation points and solution branches via Newton's method. Linear thresholds are compared to those obtained for a pure fluid. It is found that for large enough Soret coefficient, convection is initiated predominantly by solutal effects and leads to a single large roll. Computed bifurcation diagrams show a marked transition from a weakly convective Soret regime to a strongly convective Marangoni regime when the threshold for pure fluid thermal convection is passed. The presence of many secondary bifurcations means that the mode of convection at the onset of instability is often observed only over a small range of Marangoni number. In particular, two-roll states with up-flow at the centre succeed one-roll states via a well-defined sequence of bifurcations. When convection is oscillatory at onset, the limit cycle is quickly destroyed by a global (infinite-period) bifurcation leading to subcritical steady convection.

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Valenti, Sofia, Claudio Cazorla, Michela Romanini, Josep Tamarit et Roberto Macovez. « Eutectic Mixture Formation and Relaxation Dynamics of Coamorphous Mixtures of Two Benzodiazepine Drugs ». Pharmaceutics 15, n^o 1 (5 janvier 2023) : 196. http://dx.doi.org/10.3390/pharmaceutics15010196.

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The formation of coamorphous mixtures of pharmaceuticals is an interesting strategy to improve the solubility and bioavailability of drugs, while at the same time enhancing the kinetic stability of the resulting binary glass and allowing the simultaneous administration of two active principles. In this contribution, we describe kinetically stable amorphous binary mixtures of two commercial active pharmaceutical ingredients, diazepam and nordazepam, of which the latter, besides being administered as a drug on its own, is also the main active metabolite of the other in the human body. We report the eutectic equilibrium-phase diagram of the binary mixture, which is found to be characterized by an experimental eutectic composition of 0.18 molar fraction of nordazepam, with a eutectic melting point of Te = 395.4 ± 1.2 K. The two compounds are barely miscible in the crystalline phase. The mechanically obtained mixtures were melted and supercooled to study the glass-transition and molecular-relaxation dynamics of amorphous mixtures at the corresponding concentration. The glass-transition temperature was always higher than room temperature and varied linearly with composition. The Te was lower than the onset of thermal decomposition of either compound (pure nordazepam decomposes upon melting and pure diazepam well above its melting point), thus implying that the eutectic liquid and glass can be obtained without any degradation of the drugs. The eutectic glass was kinetically stable against crystallization for at least a few months. The relaxation processes of the amorphous mixtures were studied by dielectric spectroscopy, which provided evidence for a single structural (α) relaxation, a single Johari–Goldstein (β) relaxation, and a ring-inversion conformational relaxation of the diazepinic ring, occurring on the same timescale in both drugs. We further characterized both the binary mixtures and pure compounds by FTIR spectroscopy and first-principles density functional theory (DFT) simulations to analyze intermolecular interactions. The DFT calculations confirm the presence of strong attractive forces within the heteromolecular dimer, leading to large dimer interaction energies of the order of −0.1 eV.

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Kumar, Raman, Raman Kumar et Vir S. Rangra. « Dielectric Relaxation of Binary Mixtures of Tetrahydrofuran and N-Methylformamide in Benzene Solution Using Microwave Absorption Studies ». Zeitschrift für Naturforschung A 65, n^o 1-2 (1 janvier 2010) : 141–44. http://dx.doi.org/10.1515/zna-2010-1-216.

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AbstractUsing standard standing wave microwave X-band technique and following Gopala Krishna’s single frequency (9.90 GHz) concentration variational method, the dielectric relaxation times τ and the dipole moments μ of dilute solutions of Tetrahydrofuran (THF), N-methylformamide (NMF), and THF+NMF binary mixtures in benzene solutions have been calculated at different temperatures (25°C, 30°C, 35°C, and 40°C). The energy parameters (ΔHε , ΔFε , ΔSε ) for the dielectric relaxation process for the THF+NMF binary mixture containing 30 mol% THF have been calculated at 25°C, 30°C, 35°C, and 40°C and compared with the corresponding viscosity parameters. A good agreement between the free energy of activation from these two sets of values shows that the dielectric relaxation process like the viscous flow process can be treated as a rate process. From relaxation time behaviour of THF and NMF binary mixture in benzene solution, solute-solute types of the molecular association has been proposed.

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Trivedi, Chintan M., Vipinchandra A. Rana et Hemantkumar A. Chaube. « Microwave Dielectric Relaxation in Binary Mixtures of Pyridine and 1-Propanol at Different Temperatures ». Solid State Phenomena 209 (novembre 2013) : 86–89. http://dx.doi.org/10.4028/www.scientific.net/ssp.209.86.

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Dielectric constant (ε′) and Dielectric loss (ε″) of the binary mixtures of the pyridine and 1-propanol have been measured at microwave frequencies of X-band and J-band at 303,313 and 323K temperatures. Static dielectric permittivity (ε0) of the liquid samples has been determined using precision LCR meter. Dielectric permittivity at optical frequency (ε∞) has also been measured. Determined values of Static dielectric permittivity (ε0) and complex permittivity (ε*) at 9.1 GHz frequency were used to evaluate relaxation time (τ). Determined parameters have been interpreted in terms of molecular interaction among the molecular species of the binary mixtures.

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Babu, Shaik, et A. Radhakrishna Murthy. « Ultrasonic Studies on Binary Mixtures of Acetyl Acetone at 301K ». E-Journal of Chemistry 8, n^o 3 (2011) : 1094–101. http://dx.doi.org/10.1155/2011/353187.

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The ultrasonic velocity (U), density (ρ) and viscosity (η) measurements have been carried out for the binary mixtures of acetyl acetone with benzene, carbon tetra chloride and isoamyl alcohol at 301 K. From the measured values of ultrasonic velocity, density and viscosity, parameters such as internal pressure (πi), free volume (Vƒ) and acoustical parameters such as adiabatic compressibility (β), inter molecular free length (Lƒ), acoustic impedance (Z), relaxation time (τ) have been calculated. The results have been analyzed and interpreted in terms of molecular interactions.

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Quiligotti, S. « On bulk growth mechanics of solid-fluid mixtures ». Theoretical and Applied Mechanics, n^o 28-29 (2002) : 277–88. http://dx.doi.org/10.2298/tam0229277q.

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This work aims at investigating the possibility to account for the volumetric growth of a binary solid-uid mixture, within the context of biomechanical perspectives in rational mixture theories. Growth phenomena are coarsely taken into account by describing the time evolution of the solid stress-free configuration, whose introduction contributes a part of the constitutive information to the resulting dynamics, while enriching the kinematical description of the mixture. The issue of invariance requirements under changes in observer is also addressed, and some relevant constitutive implications are briey outlined. .

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Maridevarmath, C. V., et G. H. Malimath. « Studies on dielectric relaxation in relation to viscosity of some anilines, phenol, and their binary mixtures at microwave frequencies ». Canadian Journal of Physics 97, n^o 2 (février 2019) : 210–15. http://dx.doi.org/10.1139/cjp-2018-0136.

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In the present work, the study of variation of relaxation time (τ) with viscosity of the medium (η) is carried out on four polar samples: 2-Nitroaniline, 4-Bromoaniline, 4-Chloroaniline, 4-Chlorophenol, and also on the binary mixture of 2-Nitroaniline + 4-Bromoaniline at room temperature by using microwave bench operating at a frequency of 9.59 GHz. In this regard, the different parameters like dielectric constant ([Formula: see text]), dielectric loss ([Formula: see text]), relaxation time (τs), macroscopic steady state viscosity (ηs), dynamic viscosity (ηd), and viscoelastic relaxation time (τve) were determined for all the systems. It is observed that the relaxation time (τs) increases with the increase in the viscosity of the medium for all the systems. Plots of log(τs) versus log(ηs) for all the systems show that variation of relaxation time is found to be nonlinear in the higher viscosity regions. This suggests the failure of Debye’s theory at these regions. Further, the nonlinear behaviour of relaxation time with the viscosity is explained by using the viscoelastic model suggested by Barlow et al. (Proc. R. Soc. A 309, 473 (1969). doi: 10.1098/rspa.1969.0053 ). It is also observed that macroscopic steady state viscosity (ηs) values are greater than the dynamic viscosity (ηd), and viscoelastic relaxation time (τve) values were found to be lower compared to the relaxation time (τs). These results suggest that the effective frictional resistance experienced by the molecules during reorientation is lower and the measured values of macroscopic steady state viscosity (ηs) are frequency dependent.

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Kolz, J., Y. Yarovoy, J. Mitchell, M. L. Johns et L. F. Gladden. « Interactions of binary liquid mixtures with polysaccharides studied using multi-dimensional NMR relaxation time measurements ». Polymer 51, n^o 18 (août 2010) : 4103–9. http://dx.doi.org/10.1016/j.polymer.2010.07.004.

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Krasnyuk, Igor B. « Surface-directed multi-dimensional wave structures in confined binary mixtures ». International Journal of Computational Materials Science and Engineering 04, n^o 04 (décembre 2015) : 1550023. http://dx.doi.org/10.1142/s2047684115500232.

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In this paper, we consider the process of formation of wave structures in binary mixtures: for example, polymer chains or binary alloys. This process is described by the three-dimensional linear Cahn–Hilliard equation with nonlinear dynamical boundary conditions. The dynamical boundary conditions with “feedback” describe processes of cyclic crystallization and melting, depending on temperature as on a parameter. We describe an initial value boundary problem in cube and in square. It is shown that by action of boundary conditions in cube appears wave structures of relaxation, pre-turbulent and turbulent type. For large time, the wave patterns are in the form of recurrent parallelepiped in volume or parallelogram in plane. Applications to study separation of polymer blends in the square.

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Elangovan, S., et S. Mullainathan. « Dielectric Relaxation Studies of Ethyl Formate with Primary Alcohols using Time Domain Reflectometry ». Material Science Research India 9, n^o 1 (20 juin 2012) : 81–83. http://dx.doi.org/10.13005/msri/090110.

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Dielectric relaxation studies of ethylformate with 1-propanol,1-butanol and 1-pentanol binary mixtures have been carried out at micro frequency range 9.36 GHZ at temperature of 303K.Different dielectric parameters like dielectric constant(ε’ ),dielectric loss (ε’’) ,Static dielectric constant (ε0) and dielectric constant at optical frequency (ε∞) have been determined. The Relaxation time (ε) has been obtained by Higasi and Cole-Cole method. The dielectric constant (τ0) and relaxation time (τ) decreased with increasing the concentration of ethylformate in alcohol system. The relaxation time (τ) increased with increase in chain length of the alcohols. The result shows that the strength of this molecular interaction depends upon the carbon chain length of the alcohols. Hence the proton donating ability of alcohols is in the order of 1-propanol<1-butanol<1-pentanol

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Patel, Shivani P., Ashvin N. Prajapati, H. P. Vankar et V. A. Rana. « Dielectric Dispersion Response of Binary Mixtures of n-Butanol and Valeronitrile ». Advanced Materials Research 1169 (18 mars 2022) : 73–77. http://dx.doi.org/10.4028/p-e8zq99.

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Complex permittivity spectra of various concentrations (0.0 → 1.0) of n-Butanol and its mixtures with Valeronitrile were obtained in the radio and microwave frequency range (0.2 GHz to 20 GHz) using Vector network analyzer (VNA). Complex permittivity data points were fitted into Havriliak-Negami Model. CNLS fitting using LEVMW software used to obtain dielectric parameters. Excess static dielectric constant and excess inverse relaxation time for the binary mixtures were calculated and fitted in Redlich-Kister polynomial to derive the binary coefficients and standard deviations. Variation of these parameters were discussed in terms molecular interaction between molecular species.

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Sylvester, M. Maria, T. Ganesh, D. J. S. Anand Karunakaran, P. Senthilkumar, Praveen G. Hudge et A. C. Kumbharkhane. « Dielectric dispersion and thermodynamic behavior of stearic acid binary mixtures with alcohol as co-solvent using time domain reflectometry ». Journal of Advanced Dielectrics 07, n^o 04 (août 2017) : 1750027. http://dx.doi.org/10.1142/s2010135x17500278.

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Dielectric permittivity and relaxation dynamics of binary and ternary mixture of stearic acid on various concentration and their thermodynamic effects are studied. The static dielectric constant ([Formula: see text]), dielectric permittivity ([Formula: see text]) and dielectric loss ([Formula: see text]) are found by bilinear calibration. The relaxation time ([Formula: see text]), dielectric strength ([Formula: see text]) and the excess permittivity ([Formula: see text]) are found. The thermodynamic parameters such as enthalpy ([Formula: see text]), entropy ([Formula: see text]) and Gibb’s free energy ([Formula: see text]) are evolved. The significant changes in dielectric parameters are due to the intramolecular and intermolecular interactions in response to the applied frequency. The permittivity spectra of stearic acid–alcohol in the frequency range of 10[Formula: see text]MHz to 30[Formula: see text]GHz have been measured using picoseconds Time Domain Reflectometry (TDR). The dielectric parameters ([Formula: see text], [Formula: see text], [Formula: see text]) are found by bilinear calibration method. Influence of temperature in intermolecular interaction and the relaxation process are also studied. The FT-IR spectral analysis reveals that the conformation of functional groups and formation for hydrogen bonding are present in both binary and ternary mixtures of stearic acid.

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Beljin-Čavić, M., I. Lončarević, Lj Budinski-Petković, Z. M. Jakšić et S. B. Vrhovac. « Simulation study of random sequential deposition of binary mixtures of lattice animals on a three-dimensional cubic lattice ». Journal of Statistical Mechanics : Theory and Experiment 2022, n^o 5 (1 mai 2022) : 053206. http://dx.doi.org/10.1088/1742-5468/ac68dd.

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Abstract Random sequential adsorption of mixtures of objects of various shapes on a three-dimensional (3D) cubic lattice is studied numerically by means of Monte Carlo simulations. Depositing objects are ‘lattice animals’, made of a certain number of nearest neighbor sites on a lattice. We analyzed binary mixtures composed of shapes of equal size, n = 3, 4, 5. We concentrate here on the influence of geometrical properties of the shapes on the jamming coverage θ J and on the temporal evolution of the density θ(t). The approach of the coverage θ(t) to the jamming limit θ J is found to be exponential, θ J − θ(t) ∼ exp(−t/σ), both for the mixtures and their components. The values of the relaxation time σ are determined by the number of different orientations m that lattice animals can take when placed on a cubic lattice. The value of the relaxation time σ for a mixture is approximately twice the relaxation time for the pure component shape with a larger number m of possible orientations. Depending on the local geometry of the objects making the mixture, the jamming coverage of a mixture θ J can be either greater than both single-component jamming coverages or it can be in between these values. The first case is the most common, while in the second case, the jamming density of the mixture is very close to the higher jamming density for the pure component shapes. For a majority of the investigated mixtures, a component with a larger number of orientations m has a larger value of the fractional jamming density.

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Bruno, Domenico, et Vincent Giovangigli. « Internal Energy Relaxation Processes and Bulk Viscosities in Fluids ». Fluids 7, n^o 11 (19 novembre 2022) : 356. http://dx.doi.org/10.3390/fluids7110356.

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Internal energy relaxation processes in fluid models derived from the kinetic theory are revisited, as are related bulk viscosity coefficients. The apparition of bulk viscosity coefficients in relaxation regimes and the links with equilibrium one-temperature bulk viscosity coefficients are discussed. First, a two-temperature model with a single internal energy mode is investigated, then a two-temperature model with two internal energy modes and finally a state-to-state model for mixtures of gases. All these models lead to a unique physical interpretation of the apparition of bulk viscosity effects when relaxation characteristic times are smaller than fluid times. Monte Carlo numerical simulations of internal energy relaxation processes in model gases are then performed, and power spectrums of density fluctuations are computed. When the energy relaxation time is smaller than the fluid time, both the two temperature and the single-temperature model including bulk viscosity yield a satisfactory description. When the energy relaxation time is larger than the fluid time, however, only the two-temperature model is in agreement with Boltzmann equation. The quantum population of a He-H2 mixture is also simulated with detailed He-H2 cross sections, and the resulting bulk viscosity evaluated from the Green–Kubo formula is in agreement with the theory. The impact of bulk viscosity in fluid mechanics is also addressed, as well as various mathematical aspects of internal energy relaxation and Chapman–Enskog asymptotic expansion for a two-temperature fluid model.

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Matteson, A., J. P. Tomanic, M. M. Herron, D. F. Allen et W. E. Kenyon. « NMR Relaxation of Clay/Brine Mixtures ». SPE Reservoir Evaluation & ; Engineering 3, n^o 05 (1 octobre 2000) : 408–13. http://dx.doi.org/10.2118/66185-pa.

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Summary Effective interpretation of nuclear magnetic resonance (NMR) logs in shaly sands requires an understanding of the NMR contribution of clays. Of particular importance is the role of clays in the rapidly relaxing part of the NMR signal. In this study we measured the transverse relaxation time spectrum T2 of brine mixed with four clays (illite, smectite, kaolinite and glauconite) as a function of compaction. The Larmor frequency was 2 MHz and the echo spacing 0.16 ms. Mild compaction was achieved by centrifuging the clay slurry at three successive pressures ranging from 1 to 125 psi. Highly compacted samples were produced in a uniaxial press at six sequential pressures ranging from 500 to 16,000 psi. Each clay/brine slurry and its associated compacted sample showed a single peak in the T2 distribution spectrum. A second peak, which could be interpreted as the "clay-bound water," was never observed. The T2 peak position shifted to faster relaxation times as compaction increased, in proportion to the pore volume-to-surface ratio, Vp/As. The single peak and Vp/As proportionality are consistent with fast diffusion between the pore water and the monolayer of water on the clay surface. Surface relaxivity varied among the four clay minerals; glauconite, the clay with the highest magnetic susceptibility and iron content had the largest surface relaxivity. These results have important implications for the interpretation of NMR logs in shaly sands. Because of the effects of compaction and to a lesser extent the iron content on a clay's T2 peak position, it is not possible to independently determine clay type from some characteristic relaxation time. These data also imply that it is not feasible to estimate the cation exchange capacity from a single time cutoff of the T2 distribution without additional information such as laboratory measurements or other log data. Introduction Nuclear magnetic resonance logging has become an important tool in evaluating a formation's petrophysical properties. The unique and valuable advantage that NMR provides is pore size distribution information. No other logging method provides these data, which are the key component of log-based estimates of capillary-bound water volume, and permeability to flow.1 It has been proposed that NMR logging can be extended to estimate clay-bound water volumes, and identify clay minerals. Clay-bound water volume, important in determining water saturation from resistivity, has been correlated with the short-T2 less than 3 ms, porosity of 45 oilfield sandstones.2 Prammer et al.'s3 NMR clay/brine study found that the T2 distribution of clay-bound water associated with kaolinite and chlorite was greater than 3 ms, for illite it ranged between 1 and 2 ms and for smectite it was less than 1 ms. Observed T2 's were then used as an indicator of cation exchange capacity (CEC) because the number of available exchange sites is proportional to a clay's specific surface area. CEC is fundamental to converting bulk resistivity measurements into water saturation. The ability to estimate clay-bound water, and to identify the clay type, from NMR T2 distributions is not compatible with the ability to determine pore size distribution from the same data. In the first two cases the molecular diffusion rate of water in the pores must be slow, whereas in the latter case it is assumed to be fast. For example, consider a monolayer of water on the surface of room-dry clay. The monolayer has a short relaxation time, less than a millisecond, because of its interaction with the solid rock. Now fill the void space between the clay particles with water and consider the two extreme cases. In the first case, there is no molecular diffusion (exchange) between the surface-monolayer water and bulk water. Thus, the T2 spectrum will contain two separate peaks, one associated with the surface-monolayer water at less than a millisecond and one associated with the bulk water. In the opposite case, molecular diffusion is highly effective, and both the surface monolayer and bulk water have a common relaxation time, a single peak in the T2 spectrum with time constant: 1 T 2 = ρ s ( A s V p ) . ( 1 ) In this equation, which provides the fundamental connection between T2 and pore size, the term ?2 is the surface relaxivity parameter that indicates the capacity of the rock to cause the decay of magnetization in the water. Fig. 1 is a conceptual drawing of a T2 distribution for a sandstone that includes fluid in small pores that are typically associated with clays, capillary-bound and producible fluid. The objective of this study was to determine whether it is possible to infer a clay-bound water volume (peak or T2 cutoff), or clay type, and a pore size distribution from a NMR distribution spectrum. To achieve this goal we designed a set of experiments that examined the NMR relaxation of clay/brine mixtures at various compaction states. In contrast to shaly sands, the clay/brine mixtures provided the means to minimize the pore volume-to-surface ratio, so that any water-monolayer-related signal might be detected. The pore volume-to-surface ratio was easily varied through compaction, and the monomineralic samples enable the NMR response of individual clay types to be evaluated. We chose to study four clays commonly found in oil-bearing sedimentary environments: kaolinite, illite, smectite and glauconite. Experimental Procedures Samples of illite and glauconite were obtained from Wards Natural Science Establishment. Kaolinite and smectite (Ca Montmorillonite) were procured from ECC Intl., Georgia Kaolin Co. and the Source Clay Minerals Repository, respectively. Various physical properties of the clays were measured. Prior to the surface area and magnetic susceptibility measurements, the clays were dried overnight in a vacuum oven at 100°C. Surface area measurements were collected using the Micromeritics Gemini 2360 with nitrogen gas as adsorbate, and magnetic susceptibilities were measured on a Johnson Matthey MSB-AUTO magnetic susceptibility balance. CEC measurements were taken using the ammonium acetate/ammonium ion-specific electrode method by David K. Davies & Assoc., Inc. Table 1 is a summary of clay type, clay origin and clay physical properties. The samples were analyzed for mineralogy using dual-range Fourier transform infrared (FTIR) spectroscopy.4 In addition, the samples were sent to X-Ray Assay Laboratories for chemical analyses (Table 2). The mineralogy data indicate the presence of quartz in the illite sample. Consequently, a <2 ?m fraction of the sample was extracted by centrifuging the illite and drying the supernatant. The physical properties for these clays are in good agreement with those in the literature.5 The clay samples used for the room-dry and clay/brine mixture NMR experiments were kept at room temperature and at typical laboratory humidity conditions of 50%. To evaluate whether clay samples have a measurable NMR signal at room-dry conditions, samples were prepared by placing the clay in a test tube and sealing it off with a stopper and Teflon tape.

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Elangovan, Sampandam, Tilahun Diriba Garbi et Senbeto Kena Etana. « Dielectric Relaxation Studies Between Brompheniramine with 1-Butanol, 1-Pentanol and 1-Hexanol at 303K ». Material Science Research India 17, n^o 3 (25 décembre 2020) : 230–35. http://dx.doi.org/10.13005/msri/170305.

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The dielectric relaxation studies are vital in analyzing the strength of the inter molecular interaction between the binary liquid systems [1-4]. Jyostna et al. [5] reported thermodynamic parameters of isoamyl alcohols and mono clinic aromatic liquid mixtures. Shakila et al. [6] studied the dielectric properties of aromatic alcohols and aliphatic amines at different temperatures. In general, dielectric relaxation time varies with the inter molecular forces acting between the molecules in the selected liquid mixtures. Brompheniramine is one of the critical compounds of an amine group with spectacular applications, including pharmaceutical industries [7]. Higher carbon chain length alcohols are having self associated and proton donating ability in the liquid mixtures. The variations in the dielectric constant (є’), dielectric loss (є’’), static dielectric constant (є0) and the dielectric constant at an optical frequency (є∞) with a range of brompheniramine concentrations with 1-butanol,1-pentanol and 1-hexanol systems are useful in the applied research and chemical industries. Moreover, the variations in the dielectric constant and dielectric relaxation time should be useful in the analysis of intermolecular interaction between the functional group of the selected liquid mixtures. This research work attempts to analyse the intermolecular interaction between the brompheniramine and 1-butanol,1-pentanol and 1-hexanol at 303K using time domain reflectometry techniques.

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Mohan, A., M. Malathi, S. S. Shaikh et A. C. Kumbharkhane. « Thermodynamic and Molecular Dielectric Relaxation Studies of Polar–Polar Binary Mixtures Using Time Domain Reflectometry Technique ». Journal of Solution Chemistry 45, n^o 2 (février 2016) : 221–34. http://dx.doi.org/10.1007/s10953-016-0441-6.

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MANJUNATH, M. S., et J. SANNAPPA. « MOLECULAR INTERACTION STUDY OF N-BENZYLFORMAMIDE WITH 1-ALCOHOLS USING X-BAND MICROWAVE ». Modern Physics Letters B 24, n^o 02 (20 janvier 2010) : 195–200. http://dx.doi.org/10.1142/s0217984910022251.

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The secondary amide unit is a subject of particular interest, because of its occurrence in peptides and proteins. Molecular interaction between N-benzylformamide (NBF) with 1-alcohols (1-propanol, 1-butanol, 1-pentanol) has been studied in carbon tetrachloride by using X-band microwave bench at 936 GHz. Dielectric constant (ε') and dielectric loss (ε″) of alcohol and NBF and their binary mixture for different mole fractions of NBF have been determined. Dielectric relaxation time (τ) of the binary system is obtained by both Higasi's method and the Gopalakrishna single-frequency concentration variational method. The results show that the most likely interaction between alcohols and NBF is 1:1 complex for binary mixture through the free hydroxyl group of the alcohol and the carbonyl group of NBF. The alkyl chain-length of both alcohol and amide plays an important role in the determination of the strength of hydrogen bond ( O – H : C = O ) formed. The variation of relaxation time of NBF+1-alcohol mixtures in CCl 4 indicates a weak solute-solvent type of molecular association. The result shows that as the relaxation time of the proton acceptor increases, the donating ability of the solute environment increase.

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Trivedi, C. M., V. A. Rana, P. G. Hudge et A. C. Kumbharkhane. « Dielectric relaxation studies of binary mixture of β-picoline and methanol using time domain reflectometry at different temperatures ». Journal of Advanced Dielectrics 06, n^o 03 (septembre 2016) : 1650022. http://dx.doi.org/10.1142/s2010135x16500223.

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Complex permittivity spectra of binary mixtures of varying concentrations of [Formula: see text]-picoline and Methanol (MeOH) have been obtained using time domain reflectometry (TDR) technique over frequency range 10 MHz to 25 GHz at 283.15, 288.15, 293.15 and 298.15 K temperatures. The dielectric relaxation parameters namely static permittivity ([Formula: see text]), high frequency limit permittivity ([Formula: see text]) and the relaxation time ([Formula: see text]) were determined by fitting complex permittivity data to the single Debye/Cole-Davidson model. Complex nonlinear least square (CNLS) fitting procedure was carried out using LEVMW software. The excess permittivity ([Formula: see text]) and the excess inverse relaxation time (1/[Formula: see text] which contain information regarding molecular structure and interaction between polar–polar liquids were also determined. From the experimental data, parameters such as effective Kirkwood correlation factor (geff), Bruggeman factor (fB) and some thermo dynamical parameters have been calculated. Excess parameters were fitted to the Redlich–Kister polynomial equation. The values of static permittivity and relaxation time increase nonlinearly with increase in the mol–fraction of MeOH at all temperatures. The values of excess static permittivity ([Formula: see text]E) and the excess inverse relaxation time (1/[Formula: see text] are negative for the studied [Formula: see text]-picoline — MeOH system at all temperatures.

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Alamelumangai, G., et N. Santhi. « Acoustical Studies on Binary Liquid Mixtures of Some 1,3,4-Oxadiazole Derivatives with Acetone at 303.15 K ». International Letters of Chemistry, Physics and Astronomy 24 (décembre 2013) : 124–33. http://dx.doi.org/10.18052/www.scipress.com/ilcpa.24.124.

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The wide spread use of 1,3,4-oxadiazoles as a scaffold in medicinal chemistry establishes this moiety as an important bioactive class of heterocycles. In the present study ultrasonic velocity (u), density (ρ) and viscosity (η) have been measured at frequency 2 MHz in the binary mixtures of 1,3,4-oxadiazole derivatives in acetone at 303.15 K using ultrasonic interferometer technique. The measured value of ultrasonic velocity, density and viscosity have been used to estimate the acoustical parameters namely adiabatic compressibility (βad), relaxation time (τ), acoustic impedance (Zi), free length (Lf), free volume (Vf) and internal pressure (πi), with a view to investigate the nature and strength of molecular interactions. The obtained result support the occurrence of molecular association through hydrogen bonding in the binary liquid mixtures.

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Alamelumangai, G., et N. Santhi. « Acoustical Studies on Binary Liquid Mixtures of Some 1,3,4-Oxadiazole Derivatives with Acetone at 303.15 K ». International Letters of Chemistry, Physics and Astronomy 24 (26 décembre 2013) : 124–33. http://dx.doi.org/10.56431/p-42k70r.

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The wide spread use of 1,3,4-oxadiazoles as a scaffold in medicinal chemistry establishes this moiety as an important bioactive class of heterocycles. In the present study ultrasonic velocity (u), density (ρ) and viscosity (η) have been measured at frequency 2 MHz in the binary mixtures of 1,3,4-oxadiazole derivatives in acetone at 303.15 K using ultrasonic interferometer technique. The measured value of ultrasonic velocity, density and viscosity have been used to estimate the acoustical parameters namely adiabatic compressibility (βad), relaxation time (τ), acoustic impedance (Zi), free length (Lf), free volume (Vf) and internal pressure (πi), with a view to investigate the nature and strength of molecular interactions. The obtained result support the occurrence of molecular association through hydrogen bonding in the binary liquid mixtures.

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Cates, M. E., J. C. Desplat, P. Stansell, A. J. Wagner, K. Stratford, R. Adhikari et I. Pagonabarraga. « Physical and computational scaling issues in lattice Boltzmann simulations of binary fluid mixtures ». Philosophical Transactions of the Royal Society A : Mathematical, Physical and Engineering Sciences 363, n^o 1833 (5 août 2005) : 1917–35. http://dx.doi.org/10.1098/rsta.2005.1619.

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We describe some scaling issues that arise when using lattice Boltzmann (LB) methods to simulate binary fluid mixtures—both in the presence and absence of colloidal particles. Two types of scaling problem arise: physical and computational. Physical scaling concerns how to relate simulation parameters to those of the real world. To do this effectively requires careful physics, because (in common with other methods) LB cannot fully resolve the hierarchy of length, energy and time-scales that arise in typical flows of complex fluids. Care is needed in deciding what physics to resolve and what to leave unresolved, particularly when colloidal particles are present in one or both of two fluid phases. This influences steering of simulation parameters such as fluid viscosity and interfacial tension. When the physics is anisotropic (for example, in systems under shear) careful adaptation of the geometry of the simulation box may be needed; an example of this, relating to our study of the effect of colloidal particles on the Rayleigh–Plateau instability of a fluid cylinder, is described. The second and closely related set of scaling issues are computational in nature: how do you scale-up simulations to very large lattice sizes? The problem is acute for systems undergoing shear flow. Here one requires a set of blockwise co-moving frames to the fluid, each connected to the next by a Lees–Edwards like boundary condition. These matching planes lead to small numerical errors whose cumulative effects can become severe; strategies for minimizing such effects are discussed.

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Vigneswari, M., S. S. Saravanakumar, V. N. Suresh et S. Sankarrajan. « Molecular interactions in solutions of poly vinyl alcohol : an ultrasonic study ». International Journal of Advanced Chemistry 4, n^o 2 (22 juillet 2016) : 15. http://dx.doi.org/10.14419/ijac.v4i2.6333.

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Ultrasonic velocity, density, viscosity have been measured experimentally in the binary and ternary mixtures of Poly Vinyl Alcohol (PVA), water and borax with various concentration at 301.32 K. As the acoustical parameters like adiabatic compressibility, intermolecular free length, relaxation time, acoustic impedance, surface tension, Rao’s and Wada’s constant, ultrasonic attenuation and free volume would be more useful to predict and confirm the molecular interaction, these have been determined by using ultrasonic velocity, density and viscosity of the prepared solution. It has been identified that the molecular interactions in binary mixture were stronger than that of in ternary mixtures. And also there is a strong solute – solvent interaction occurring in both binary and ternary solutions. This may be due to the greater possibility of hydrogen bonding between PVA and Water molecules. When the borax is added, the molecular interaction is getting weaker due to greater affinity of borate ion towards the hydrogen in hydroxyl group of PVA.

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Wu, Yuxin, et Luca Peruzzo. « Effects of salinity and pH on the spectral induced polarization signals of graphite particles ». Geophysical Journal International 221, n^o 3 (20 février 2020) : 1532–41. http://dx.doi.org/10.1093/gji/ggaa087.

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SUMMARY The electrical property of micrometre-sized graphite particles was investigated under different particle concentration, particle size, fluid conductivity and pH conditions. Due to its large internal electronic conductivity and ability to polarize under external potential field, significant enhancement of its spectral induced polarization (SIP) responses is observed when graphite is included in sand mixtures. While a small amount of graphite inclusion significantly increases the SIP response of its mixtures with sand, further concentration increase does not necessarily lead to a proportional increase of the SIP response. This is shown to be related to the formation of graphite aggregates at higher concentrations. Changes of fluid salinity have a significant effect on graphite's SIP behaviour. This includes a positive impact on normalized chargeability and imaginary conductivity, but a negative impact on chargeability and relaxation time constant. The effect of pH on the SIP response of graphite is small but shows consistent trend, where pH increase leads to a decrease of both the chargeability and relaxation time constant. The underlying cause of this effect is not clear.

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Lemaire, Claude, et Robin L. Armstrong. « The effect of van der Waals complexes on the longitudinal proton spin relaxation time in hydrogen–argon gas mixtures ». Canadian Journal of Physics 63, n^o 2 (1 février 1985) : 179–87. http://dx.doi.org/10.1139/p85-027.

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An extensive set of measurements of the proton spin longitudinal relaxation time T1 for molecular hydrogen diluted in argon is presented. These measurements, carried out at 18.975 MHz, establish the temperature and density dependence of the relaxation time from 110 to 300 K and from 2 to 100 amagat, respectively. The T1 data, although taken in the intermediate density regime in which binary collisions lead to a characteristic linear dependence on density, ρ, exhibit a significant nonlinear dependence. This effect is attributed to the presence of van der Waals complexes (H2–Ar dimers) in the mixture and is explained as a consequence of the formation and annihilation dynamics of the dimers. A theoretical model is developed which accounts for all qualitative aspects of the data. The dimer contribution to the relaxation time is described in terms of two parameters: the dimer annihilation cross section σ and the equilibrium constant K describing the relative number of H2–Ar dimers. The cross section σ is very nearly equal to the geometric cross section. The constant K is of the order of 10−23 cm3 and in good agreement with the theoretical value. Its variation with temperature is predicted well by our calculations.

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Sannaningannavar, F. M., Narasimha H. Ayachit et D. K. Deshpande. « On the effect of temperature on the dielectric relaxation time of some phenols and certain of their binary mixtures ». Journal of Molecular Liquids 124, n^o 1-3 (février 2006) : 124–27. http://dx.doi.org/10.1016/j.molliq.2005.08.005.

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Igolnikov, Alexander, et Pavel Skripov. « Characteristic Features of Heat Transfer in the Course of Decay of Unstable Binary Mixture ». Energies 16, n^o 5 (22 février 2023) : 2109. http://dx.doi.org/10.3390/en16052109.

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This article is devoted to the study of the phenomenon of superheating of partially miscible mixtures having a lower critical solution temperature and the thermal effect accompanying the relaxation of an unstable mixture, within the framework of the problem of high-density heat flux removal. The study was carried out by using the method of the controlled pulse heating of a platinum wire probe. The characteristic heating time was from 0.2 to 180 ms. The superheating degree of the mixture relative to the diffusion spinodal exceeded 100 K. The heat flux density from the heater surface reached 13.7 MW/m2. The object of research was an aqueous solution of polypropylene glycol-425 (PPG-425). The obtained results clearly indicate that such mixtures can be used as coolants in processes where the possibility of powerful local heat release cannot be excluded. They also form the basis for expanding the phase diagram by involving in the study not-fully-stable and unstable states of the mixture.

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Raguraman, A., et N. Santhi. « Acoustical Studies on Molecular Interaction of 1,3,4-Pyrazoline Derivatives Using Ultrasonic Technique at 303.15 K ». International Letters of Chemistry, Physics and Astronomy 39 (octobre 2014) : 100–115. http://dx.doi.org/10.18052/www.scipress.com/ilcpa.39.100.

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The acoustical parameters for the binary liquid mixtures containing Pyrazoline derivatives in DMF have been estimated at 303.15 K, from the measured values of ultrasonic velocity (U), density (ρ) and viscosity (η). From these data some of acoustical parameters such as adiabatic compressibility (β), free length (Lf), acoustic impedance (Z), Rao’s constant (R), molar compressibility (W), relaxation time (τ), free volume (Vf) and internal pressure (πi), etc., have been computed using the standard relations. The results have been discussed in terms of molecular interactions.

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Raguraman, A., et N. Santhi. « Acoustical Studies on Molecular Interaction of 1,3,4-Pyrazoline Derivatives Using Ultrasonic Technique at 303.15 K ». International Letters of Chemistry, Physics and Astronomy 39 (2 octobre 2014) : 100–115. http://dx.doi.org/10.56431/p-b4wi2g.

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The acoustical parameters for the binary liquid mixtures containing Pyrazoline derivatives in DMF have been estimated at 303.15 K, from the measured values of ultrasonic velocity (U), density (ρ) and viscosity (η). From these data some of acoustical parameters such as adiabatic compressibility (β), free length (Lf), acoustic impedance (Z), Rao’s constant (R), molar compressibility (W), relaxation time (τ), free volume (Vf) and internal pressure (πi), etc., have been computed using the standard relations. The results have been discussed in terms of molecular interactions.

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Palaia, Ivan, et Anđela Šarić. « Controlling cluster size in 2D phase-separating binary mixtures with specific interactions ». Journal of Chemical Physics 156, n^o 19 (21 mai 2022) : 194902. http://dx.doi.org/10.1063/5.0087769.

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By varying the concentration of molecules in the cytoplasm or on the membrane, cells can induce the formation of condensates and liquid droplets, similar to phase separation. Their thermodynamics, much studied, depends on the mutual interactions between microscopic constituents. Here, we focus on the kinetics and size control of 2D clusters, forming on membranes. Using molecular dynamics of patchy colloids, we model a system of two species of proteins, giving origin to specific heterotypic bonds. We find that concentrations, together with valence and bond strength, control both the size and the growth time rate of the clusters. In particular, if one species is in large excess, it gradually saturates the binding sites of the other species; the system then becomes kinetically arrested and cluster coarsening slows down or stops, thus yielding effective size selection. This phenomenology is observed both in solid and fluid clusters, which feature additional generic homotypic interactions and are reminiscent of the ones observed on biological membranes.

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Hürlimann, M. D., L. Venkataramanan et C. Flaum. « The diffusion–spin relaxation time distribution function as an experimental probe to characterize fluid mixtures in porous media ». Journal of Chemical Physics 117, n^o 22 (8 décembre 2002) : 10223–32. http://dx.doi.org/10.1063/1.1518959.

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Ilyas, Suhaib Umer, Rajashekhar Pendyala et Narahari Marneni. « Settling Characteristics of Alumina Nanoparticles in Ethanol-Water Mixtures ». Applied Mechanics and Materials 372 (août 2013) : 143–48. http://dx.doi.org/10.4028/www.scientific.net/amm.372.143.

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Nanofluids are considered as promising heat transfer fluids due to enhanced heat transfer ability as compared to the base fluid alone. Knowledge of settling characteristics of nanofluids has great importance towards stability of nanosuspensions. Sedimentation behavior of Alumina nanoparticles due to gravity has been investigated using different proportions of ethanol-water binary mixtures. Nanoparticles of 40 nm and 50 nm are used in this investigation at 23°C. Sediment height with respect to time is measured by visualization method in batch sedimentation. The effect of sonication on the sedimentation behavior is also studied using ultrasonic agitator. The effect of particle diameter, nanoparticle concentration and ethanol-water proportion on sedimentation behavior of nanofluids has been investigated and discussed.

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Schmitt, B., C. Kiefer et A. Schütze. « Novel microthermal sensor principle for determining the mixture ratio of binary fluid mixtures using Föppl vortices ». Journal of Sensors and Sensor Systems 4, n^o 1 (18 juin 2015) : 239–47. http://dx.doi.org/10.5194/jsss-4-239-2015.

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Abstract. A novel sensor principle for determining binary fluid mixtures of known components is presented, making use of different thermal and rheological properties of the mixture's components. Using a microheater, a heat pulse is introduced in the mixture. The resulting temperature increase depends on the thermal properties of the mixture, allowing determination of the mixture ratio. Placing a bluff body in the fluid channel causes the formation of a stationary pair of vortices behind the body. The length of the vortex pair depends on the mixture's viscosity and thus its composition. By placing the microheater in the vortex area and making use of forced convection which changes with the size of the vortex, the sensitivity for determination of the mixture ratio can be increased by a factor of 2.5 compared to the direct thermal measurement. The flow velocity is measured independently of the mixture ratio using time-of-flight thermal anemometry.

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Stelmaszczyk, Kamil, Ewelina Karpierz-Marczewska, Valeri Mikhnev, Grzegorz Cywinski, Thomas Skotnicki et Wojciech Knap. « Ultrafast Time-of-Flight Method of Gasoline Contamination Detection Down to ppm Levels by Means of Terahertz Time-Domain Spectroscopy ». Applied Sciences 12, n^o 3 (4 février 2022) : 1629. http://dx.doi.org/10.3390/app12031629.

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In this article, we present the possibility of using terahertz time-domain spectroscopy to detect trace, ppm-level (%wt.) concentrations of admixtures in 95-octane lead-free gasoline in straightforward time-of-flight (pulse-delay) measurements performed directly in the liquid. The method was tested on samples containing 75–0.0125% of isopropanol and 0.3–0.0250% of water. The detection limits for isopropanol and water content were determined to be 125 ppm and 250 ppm, respectively, approaching the limits of much more complicated and time-consuming methods (like spectroscopy of the vapor phase). The measured pulse delays were compared with theoretical calculations using the modified Gladstone-Dale mixing rule for the solutions. The comparison demonstrated good agreement for gasoline-alcohol mixtures and large discrepancies for gasoline-water mixtures, suggesting that gasoline-water mixtures cannot be considered idealized binary mixtures. Our results clearly show that the pulse time delay measurement by THz-TDS is a fast and sensitive method of gasoline contamination detection and, as such, can be easily integrated with industrial online real-time quality control applications.

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Vasan, S. T., Narasimha H. Ayachit et D. K. Deshpande. « On the effect of temperature on the dielectric relaxation time of some benzene derivatives and certain of their binary mixtures ». Physics and Chemistry of Liquids 44, n^o 5 (octobre 2006) : 513–19. http://dx.doi.org/10.1080/00319100600643823.

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Srisanthi, K., T. Vishwam et S. Sreehari Sastry. « Ultrasonic, Refractometry, FT-IR and DFT Studies on Hydrogen Bonding Interactions of Ethylene Glycol/Hexanol Binary Mixtures ». Asian Journal of Chemistry 34, n^o 5 (2022) : 1171–82. http://dx.doi.org/10.14233/ajchem.2022.23627.

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The density (ρ), ultrasonic velocity (U), viscosity (η) and refractometry (nD) measurements are performed on the ethylene glycol/hexanol binary liquid mixtures in the range of temperatures 298.15-323.15 K. Various parameters such as adiabatic compressibility (β), acoustic impedance (Z), intermolecular free length (Lf), internal pressure (π) and relaxation time (τ) were calculated based on the experimentally determined values. The excess parameters were calculated to interpret the hydrogen bond networks and environment associated with the liquid solution. The interaction energy between the mixture components is analyzed using the DFT-B3LYP calculations using 6-311+G(d,p), 6-311++G(d,p) basis sets. The FT-IR spectra support the hydrogen bond in the system. The optimization energy, dipole moment of the components were also represented to correlate the measured parameters. The various theories of ultrasonic velocities and mixing rules for refractive index values were also attempted to estimate the ultrasonic speed, refractive index values of the ethylene glycol/hexanol binary system.

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Khan, Zamir S., M. P. Lokhande, Avadhut Deshmukh et A. C. Kumbharkhane. « Dielectric relaxation study of aqueous ethylene glycol mono-methyl ether (EGME) with water using time domain reflectometry technique in the frequency range 10MHz to 50GHz ». Journal of Advanced Dielectrics 10, n^o 03 (15 avril 2020) : 2050004. http://dx.doi.org/10.1142/s2010135x20500046.

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Résumé :

The Complex permittivity spectra of glycol ether (GE) compounds such as ethylene glycol mono-methyl ether (EGME) with water mixture over entire concentration range and in temperature range of 10–25∘C have been determined using Time Domain Reflectometry (TDR) technique in the frequency range 10[Formula: see text]MHz to 50[Formula: see text]GHz. The complex permittivity spectra for EGME-water were fitted in the Cole–Davidson model. The Static dielectric constant ([Formula: see text], Relaxation time ([Formula: see text], effective Kirkwood correlation factor ([Formula: see text], excess permittivity ([Formula: see text], thermodynamic parameters (activation enthalpy and activation entropy) and Bruggeman factor ([Formula: see text] have been calculated by the nonlinear least square fit method. The intermolecular interactions between EGME-water binary mixtures suggest the nonlinear behavior of dielectric parameters. The contribution of hydrogen bonding interactions among the solute–solvent mixtures is confirmed by Excess properties and Bruggeman factor.

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