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Marian Paluch - One of the best experts on this subject based on the ideXlab platform.
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Quantifying the Structural Dynamics of Pharmaceuticals in the Glassy State.
The journal of physical chemistry letters, 2012Co-Authors: Zaneta Wojnarowska, C. M. Roland, K. Kolodziejczyk, A. Swiety-pospiech, Katarzyna Grzybowska, Marian PaluchAbstract:Structural dynamics in the Glassy State of two protic ionic liquids, carvedilol phosphate and procaine hydrochloride, were characterized from analysis of changes in the conductivity relaxation times during physical aging. The obtained relaxation times, having a magnitude exceeding feasible experimental time scales and thus not directly measurable, are consistent with published data from a method that relies on the presence of a secondary relaxation. We also observe a narrowing of the relaxation dispersion, specific to higher frequencies, that is a consequence of the heterogeneous dynamics of deeply supercooled materials.
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Probing of structural relaxation times in the Glassy State of sucrose and trehalose based on dynamical properties of two secondary relaxation processes.
Physical Review E, 2011Co-Authors: Kamil Kaminski, Karolina Adrjanowicz, Ewa Kaminska, Marian PaluchAbstract:Time-dependent isothermal dielectric measurements were carried out deeply in the Glassy State on two very important saccharides: sucrose and trehalose. In both compounds two prominent secondary relaxation processes were identified. The faster one is an inherent feature of the whole family of carbohydrates. The slower one can also be detected in oligo- and polysaccharides. It was shown earlier that the $\ensuremath{\beta}$ process is the Johari-Goldstein (JG) relaxation coupled to motions of the glycosidic linkage, while the $\ensuremath{\gamma}$ relaxation originates from motions of the exocyclic hydroxymethyl unit. Recently, it was shown that the JG relaxation process can be used to determine structural relaxation times in the Glassy State [R. Casalini and C. M. Roland, Phys. Rev. Lett. 102, 035701 (2009)]. In this paper we present the results of an analysis of the data obtained during aging using two independent approaches. The first was proposed by Casalini and Roland, and the second one is based on the variation of the dielectric strength of the secondary relaxation process during aging [J. K. Vij and G. Power, J. Non-Cryst. Solids 357, 783 (2011)]. Surprisingly, we found that the estimated structural relaxation times in the Glassy State of both saccharides are almost the same, independent of the type of secondary mode. This finding calls into question the common view that secondary modes of intramolecular origin do not provide information about the dynamics of the Glassy State.
Kamil Kaminski - One of the best experts on this subject based on the ideXlab platform.
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Probing of structural relaxation times in the Glassy State of sucrose and trehalose based on dynamical properties of two secondary relaxation processes.
Physical Review E, 2011Co-Authors: Kamil Kaminski, Karolina Adrjanowicz, Ewa Kaminska, Marian PaluchAbstract:Time-dependent isothermal dielectric measurements were carried out deeply in the Glassy State on two very important saccharides: sucrose and trehalose. In both compounds two prominent secondary relaxation processes were identified. The faster one is an inherent feature of the whole family of carbohydrates. The slower one can also be detected in oligo- and polysaccharides. It was shown earlier that the $\ensuremath{\beta}$ process is the Johari-Goldstein (JG) relaxation coupled to motions of the glycosidic linkage, while the $\ensuremath{\gamma}$ relaxation originates from motions of the exocyclic hydroxymethyl unit. Recently, it was shown that the JG relaxation process can be used to determine structural relaxation times in the Glassy State [R. Casalini and C. M. Roland, Phys. Rev. Lett. 102, 035701 (2009)]. In this paper we present the results of an analysis of the data obtained during aging using two independent approaches. The first was proposed by Casalini and Roland, and the second one is based on the variation of the dielectric strength of the secondary relaxation process during aging [J. K. Vij and G. Power, J. Non-Cryst. Solids 357, 783 (2011)]. Surprisingly, we found that the estimated structural relaxation times in the Glassy State of both saccharides are almost the same, independent of the type of secondary mode. This finding calls into question the common view that secondary modes of intramolecular origin do not provide information about the dynamics of the Glassy State.
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Probing of structural relaxation times in the Glassy State of sucrose and trehalose based on dynamical properties of two secondary relaxation processes.
Physical review. E Statistical nonlinear and soft matter physics, 2011Co-Authors: Kamil Kaminski, Karolina Adrjanowicz, Ewa Kaminska, M PaluchAbstract:Time-dependent isothermal dielectric measurements were carried out deeply in the Glassy State on two very important saccharides: sucrose and trehalose. In both compounds two prominent secondary relaxation processes were identified. The faster one is an inherent feature of the whole family of carbohydrates. The slower one can also be detected in oligo- and polysaccharides. It was shown earlier that the β process is the Johari-Goldstein (JG) relaxation coupled to motions of the glycosidic linkage, while the γ relaxation originates from motions of the exocyclic hydroxymethyl unit. Recently, it was shown that the JG relaxation process can be used to determine structural relaxation times in the Glassy State [R. Casalini and C. M. Roland, Phys. Rev. Lett. 102, 035701 (2009)]. In this paper we present the results of an analysis of the data obtained during aging using two independent approaches. The first was proposed by Casalini and Roland, and the second one is based on the variation of the dielectric strength of the secondary relaxation process during aging [J. K. Vij and G. Power, J. Non-Cryst. Solids 357, 783 (2011)]. Surprisingly, we found that the estimated structural relaxation times in the Glassy State of both saccharides are almost the same, independent of the type of secondary mode. This finding calls into question the common view that secondary modes of intramolecular origin do not provide information about the dynamics of the Glassy State.
C. M. Roland - One of the best experts on this subject based on the ideXlab platform.
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Quantifying the Structural Dynamics of Pharmaceuticals in the Glassy State.
The journal of physical chemistry letters, 2012Co-Authors: Zaneta Wojnarowska, C. M. Roland, K. Kolodziejczyk, A. Swiety-pospiech, Katarzyna Grzybowska, Marian PaluchAbstract:Structural dynamics in the Glassy State of two protic ionic liquids, carvedilol phosphate and procaine hydrochloride, were characterized from analysis of changes in the conductivity relaxation times during physical aging. The obtained relaxation times, having a magnitude exceeding feasible experimental time scales and thus not directly measurable, are consistent with published data from a method that relies on the presence of a secondary relaxation. We also observe a narrowing of the relaxation dispersion, specific to higher frequencies, that is a consequence of the heterogeneous dynamics of deeply supercooled materials.
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Aging of the Secondary Relaxation to Probe Structural Relaxation in the Glassy State
Physical review letters, 2009Co-Authors: Riccardo Casalini, C. M. RolandAbstract:The importance of glass formation and the glass transition is linked to their universality, embracing many classes of materials: metallic, inorganic, and organic. There is no agreement on what drives this phenomenon; moreover, experiments are challenging due to the nonequilibrium nature of the Glassy State. We present a new approach that provides information about the very slow structural relaxation in the Glassy State and reveals the important role of the secondary relaxation. Structural (� ) relaxation times for Glassy polyvinylethylene were determined from changes in the properties of the secondary process during physical aging. These � -relaxation times exceed 3 years, making them inaccessible via direct measurement. Despite the long history of glass making, the underlying physics remains an unsolved problem, without any consensus on the microscopic origin of the slowing of the dynamics during supercooling. Time constants of liquids increase by ten decades or more, culminating in the Glassy State. The nonequilibrium nature of the glass presents special difficulties, since the physical properties depend on the thermodynamic path and also change during physical aging (the slow evolution of the glass toward equilibrium). Different cooling rates or formation pressures result in glasses with different properties [1], with subsequent aging times varying from seconds to many centuries. Aging is also a practical issue for thermoplastic polymers since it can cause properties to vary over their service life. The temperature dependence of the structural dynamics can be described by a diverging equation such as the VogelFulcher-Tamman (VFT) relation [2]:
M Paluch - One of the best experts on this subject based on the ideXlab platform.
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Probing of structural relaxation times in the Glassy State of sucrose and trehalose based on dynamical properties of two secondary relaxation processes.
Physical review. E Statistical nonlinear and soft matter physics, 2011Co-Authors: Kamil Kaminski, Karolina Adrjanowicz, Ewa Kaminska, M PaluchAbstract:Time-dependent isothermal dielectric measurements were carried out deeply in the Glassy State on two very important saccharides: sucrose and trehalose. In both compounds two prominent secondary relaxation processes were identified. The faster one is an inherent feature of the whole family of carbohydrates. The slower one can also be detected in oligo- and polysaccharides. It was shown earlier that the β process is the Johari-Goldstein (JG) relaxation coupled to motions of the glycosidic linkage, while the γ relaxation originates from motions of the exocyclic hydroxymethyl unit. Recently, it was shown that the JG relaxation process can be used to determine structural relaxation times in the Glassy State [R. Casalini and C. M. Roland, Phys. Rev. Lett. 102, 035701 (2009)]. In this paper we present the results of an analysis of the data obtained during aging using two independent approaches. The first was proposed by Casalini and Roland, and the second one is based on the variation of the dielectric strength of the secondary relaxation process during aging [J. K. Vij and G. Power, J. Non-Cryst. Solids 357, 783 (2011)]. Surprisingly, we found that the estimated structural relaxation times in the Glassy State of both saccharides are almost the same, independent of the type of secondary mode. This finding calls into question the common view that secondary modes of intramolecular origin do not provide information about the dynamics of the Glassy State.
Th. M. Nieuwenhuizen - One of the best experts on this subject based on the ideXlab platform.
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Thermodynamics of the Glassy State
2019Co-Authors: Luca Leuzzi, Th. M. NieuwenhuizenAbstract:A picture for thermodynamics of the Glassy State is introduced. It assumes that one extra parameter, the effective temperature, is needed to describe the Glassy State. This explains the classical paradoxes concerning the Ehrenfest relations and the Prigogine-Defay ratio. As a second part, the approach connects the response of macroscopic observables to a field change with their temporal fluctuations, and with the fluctuation-dissipation relation, in a generalized non-equilibrium way.
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Thermodynamic picture of the Glassy State
Journal of Physics: Condensed Matter, 2000Co-Authors: Th. M. NieuwenhuizenAbstract:A picture for the thermodynamics of the Glassy State is introduced. It assumes that one extra parameter, the effective temperature, is needed to describe the Glassy State. This explains the classical paradoxes concerning the Ehrenfest relations and the Prigogine-Defay ratio. As a second feature, the approach connects the response of macroscopic observables to a field change with their temporal fluctuations, and with the fluctuation-dissipation relation, in a generalized non-equilibrium way.
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Thermodynamic picture of the Glassy State gained from exactly solvable models
Physical review. E Statistical physics plasmas fluids and related interdisciplinary topics, 2000Co-Authors: Th. M. NieuwenhuizenAbstract:A picture for thermodynamics of the Glassy State was introduced recently by us [Phys. Rev. Lett. 79, 1317 (1997); 80, 5580 (1998)]. It starts by assuming that one extra parameter, the effective temperature, is needed to describe the Glassy State. This approach connects responses of macroscopic observables to a field change with their temporal fluctuations, and with the fluctuation-dissipation relation, in a generalized, nonequilibrium way. Similar universal relations do not hold between energy fluctuations and the specific heat. In the present paper, the underlying arguments are discussed in greater length. The main part of the paper involves details of the exact dynamical solution of two simple models introduced recently: uncoupled harmonic oscillators subject to parallel Monte Carlo dynamics, and independent spherical spins in a random field with such dynamics. At low temperature, the relaxation time of both models diverges as an Arrhenius law, which causes Glassy behavior in typical situations. In the Glassy regime, we are able to verify the above-mentioned relations for the thermodynamics of the Glassy State. In the course of the analysis, it is argued that stretched exponential behavior is not a fundamental property of the Glassy State, though it may be useful for fitting in a limited parameter regime.
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Thermodynamics of the Glassy State: Effective Temperature as an Additional System Parameter
Physical Review Letters, 1998Co-Authors: Th. M. NieuwenhuizenAbstract:A system is Glassy when the observation time is much smaller than the equilibration time. A unifying thermodynamic picture of the Glassy State is presented. Slow configurational modes are in quasi-equilibrium at an effective temperature. It enters thermodynamic relations with the configurational entropy as conjugate variable. Slow fluctuations contribute to susceptibilities via quasi-equilibrium relations, while there is also a configurational term. Fluctuation-dissipation relations also involve the effective temperature. Fluctuations in the energy are non-universal, however. The picture is supported by analytically solving the dynamics of a toy model.