Enthalpies of non-isothermal phase transitions in binary systems

Chernik, G. G.

doi:10.1016/0040-6031(93)80453-h

Cited by 9 publications

(4 citation statements)

References 23 publications

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“…The slope of the phase boundary dT/dx in the phase diagram is directly related to the DSC signal for a two-phase system [ 25 ]:

where n α is the number of moles in phase α,

is the reciprocal slope of the phase boundary and

is the second derivative of the Gibbs energy with respect to composition (always positive). Vertical phase boundaries do not provide any extra contribution to the heat capacity of the two phases, while low values of dT/dx strongly contribute to the DSC signal.…”

Section: Resultsmentioning

confidence: 99%

The role of water in the reversibility of thermal denaturation of lysozyme in solid and liquid states

Phan-Xuan

Bogdanova

Sommertune

et al. 2021

Biochemistry and Biophysics Reports

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Although unfolding of protein in the liquid state is relatively well studied, its mechanisms in the solid state, are much less understood. We evaluated the reversibility of thermal unfolding of lysozyme with respect to the water content using a combination of thermodynamic and structural techniques such as differential scanning calorimetry, synchrotron small and wide-angle X-ray scattering (SWAXS) and Raman spectroscopy. Analysis of the endothermic thermal transition obtained by DSC scans showed three distinct unfolding behaviors at different water contents. Using SWAXS and Raman spectroscopy, we investigated reversibility of the unfolding for each hydration regime for various structural levels including overall molecular shape, secondary structure, hydrophobic and hydrogen bonding interactions. In the substantially dehydrated state below 37 wt% of water the unfolding is an irreversible process and can be described by a kinetic approach; above 60 wt% the process is reversible, and the thermodynamic equilibrium approach is applied. In the intermediate range of water contents between 37 wt% and 60 wt%, the system is phase separated and the thermal denaturation involves two processes: melting of protein crystals and unfolding of protein molecules. A phase diagram of thermal unfolding/denaturation in lysozyme - water system was constructed based on the experimental data.

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“…The slope of the phase boundary dT/dx in the phase diagram is directly related to the DSC signal for a two-phase system [ 25 ]:

where n α is the number of moles in phase α,

is the reciprocal slope of the phase boundary and

Section: Resultsmentioning

confidence: 99%

The role of water in the reversibility of thermal denaturation of lysozyme in solid and liquid states

Phan-Xuan

Bogdanova

Sommertune

et al. 2021

Biochemistry and Biophysics Reports

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“…On the other hand, it was reported that when the homogeneous phase becomes biphasic, the finite heat capacity jump occurs. 29 In the thermograms from B to D in Fig. 5a, the system becomes a biphasic mixture consisting of an unfrozen state and the remaining as an ice fraction above the temperature of the gray arrows, until the ice melts completely.…”

Section: Ice Melting Behaviormentioning

confidence: 99%

Freezing and melting behavior of an octyl β-d-glucoside–water binary system – inhibitory effect of octyl β-d-glucoside on ice crystal formation

Ogawa

Asakura

Osanai

2012

Phys. Chem. Chem. Phys.

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Phase transition behavior of lyotropic liquid crystals of an octyl β-D-glucoside (OG)-water binary system during ice freezing and melting was studied by differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). Not the thermotropic, but the lyotropic phase transition due to the change of OG concentration during ice freezing and melting was observed. The concentration-temperature phase diagram of the binary system was constructed. Melting temperature of ice, T(m), lyotropic phase transition temperature, T(tr), and glass transition temperatures of unfrozen phases in the absence and presence of ice, T(g) and T(g)', were shown in the phase diagram. The phase diagram indicated that the OG aqueous system was concentrated to ca. 90-92 wt% by ice freezing and exhibited glass transition at T(g)'. An observation of the concentration-gradient specimen by the cryo-POM showed the evidence of the inhibitory effects of OG on nucleation and growth of ice crystals in the extremely high OG concentration system in which the lamellar liquid crystalline phase was formed. This study provided the importance of the influence of concentration change by ice freezing on the behaviour of the sugar-based surfactant-water system under low temperature conditions.

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“…Phase transitions in a binary system can be divided into two groups: isothermal and non-isothermal. 7 We applied different procedures when determining temperatures of the different types of transitions. The temperature of an isothermal phase transition was found as an intersection between a tangent line drawn at the point of maximum slope on the left side of the peak and the extrapolated baseline.…”

Section: Dscmentioning

confidence: 99%

Phase diagram and physicochemical properties of the n-octyl α-d-glucoside/water system

Kocherbitov

Söderman

2003

Phys. Chem. Chem. Phys.

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Enthalpies of non-isothermal phase transitions in binary systems

Cited by 9 publications

References 23 publications

The role of water in the reversibility of thermal denaturation of lysozyme in solid and liquid states

The role of water in the reversibility of thermal denaturation of lysozyme in solid and liquid states

Freezing and melting behavior of an octyl β-d-glucoside–water binary system – inhibitory effect of octyl β-d-glucoside on ice crystal formation

Phase diagram and physicochemical properties of the n-octyl α-d-glucoside/water system

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