SynopsisThe low-temperature heat capacity of collagen (in the hydrated and dehydrated states) and the large entropy of collagen in the coiled state relative to the same protein in the helical state were investigated. The heat capacity for collagen in the solid state in the temperature range 4"-50"K changes proportionally to the square of temperature (C, -7'*). Above 50'K there is a linear dependence (C, -7'). The differences in the character of temperature dependence of heat capacity for the hydrated and dehydrated collagen show the importance of the specific interaction of water molecules with polypeptide chains of this protein. The peculiarities of the temperature dependence of the heat capacity difference (X,) of hydrated denatured (random coiled) and hydrated native (helical) collagen are observed at 1 5 O , 120°, and 240°K. These differences are caused by the varying degree of ordering of the hydrate water molecules in native and denatured collagen macromolecules. At all temperatures (40-300°K) the entropy of the random coiled state is higher than that of collagen in the native state and at 298°K AS&8 = Jig* ( X , / T ) d T = 0.8 ca1/100 g O K .

The low temperature heat capacity measurements on LSCO samples containing Zn impurities have been performed by means of pulsed differential calorimetry technique. The interpretation of the Zn-concentration dependence of the residual γ-coefficient in the linear temperature part of Cel(T) at T≪Tc is consistent with a model based on the assumption of the d-wave symmetry of the order parameter of these superconducting copper oxides.

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The low-temperature heat capacity of cuprates(La2CuO4,La2−xMxCuO4(M = Sr, Ba) and Nd2−xLaxCuO4) is studied in the temperature range 2–45 K by using pulsed differential calorimetry. It is found that the coefficient of the linear term of heat capacity remains unchanged over the entire temperature interval under investigation. The special role of La atoms in the formation of the anomaly in the acoustic region of the phonon spectrum of these compounds near 6 meV is demonstrated. This anomaly is connected with peculiarities in the interaction of these atoms with the environment.

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