The heat capacity of several samples of hard cheese, semi-hard cheese and soft cheese was determined by conventional differential
scanning calorimetry (DSC) and by temperature modulated DSC. Additionally, the gross composition of the cheeses was analysed,
and equations from the literature were used to calculate the heat capacity therefrom. Both analytical methods were suitable
to determine the heat capacity of the cheese samples whereas only one out of three equations proposed for the calculation
of the heat capacity of foods from composition data led to results which were comparable with analytical data. As the equation
coefficients for particular constituents are responsible for the deviations in the calculated heat capacities the differences
between calculated and measured values increase with a decreasing moisture content of the cheeses.
Authors:Iwona Zięborak-Tomaszkiewicz, Ewa Utzig, and P. Gierycz
The heat capacity of gallium nitride has been measured by DSC method using DuPont Thermal Analyst 2100, DSC 951 unit in the
temperature range (300–850 K). The temperature dependence of the heat capacity can be presented in the following form: Cp=32.960+0.162·10−1T+2360170T−2-775370000T−3.
Authors:Iwona Zięborak-Tomaszkiewicz, R. Świerzewski, and P. Gierycz
The heat capacity of the solid indium nitride was measured, using the Calvet TG-DSC 111 differential scanning microcalorimeter
(Setaram, France), in the temperature between (314–978 K). The temperature dependence of the heat capacity can be presented
in the following form: Cp=41.400+0.499·10−3T−135502T−2−26169900 T−3.
Conventional thermodynamic expression predicts that the isobaric heat capacity decreases with increasing pressure. In model
calculations, heat capacity increases with pressure, decreases, or remains insensitive to pressure, depending on the model
applied. The expression cannot be applied to the gases, but experimental data on gases show evidently that heat capacity increases
Considering the change in enthalpy along two different paths with identical starting and ending points, we derive new expression
dCP/dP=αV, where α is the volume coefficient of thermal expansion and V is the molar volume. The expression predicts the increase in CP with pressure and can be applied to gases. The test of the new expression against accurate literature data on the heat capacity
of air, gaseous and liquid, demonstrates its validity.
Heat capacity Cp(T) of dysprosium diboride is experimentally investigated
at the temperatures of 5–300 K. On the dependence Cp(T) smooth anomaly at the temperatures of 15–20
K and sharp anomalies at Tm1=47.8
K and Tm2=178.8
K are revealed. Anomaly at Tm1
is caused, obviously, by ferromagnetic phase transition in DyB2.
The lattice contribution to DyB2 heat capacity is determined
by comparison with heat capacity of non-magnetic YB2.
The estimation of Schottky contribution to DyB2 heat
capacity is made, the scheme of splitting of the ground state of Dy3+
ion is offered.
Authors:T. Tojo, T. Atake, T. Mori, and H. Yamamura
The heat capacity of 9.70 and 11.35 mol% yttria stabilized zirconia ((ZrO2)1–x(Y2O3)x; x=0.0970, 0.1135) was measured by adiabatic calorimetry between 13 and 300 K, and some thermodynamic functions were calculated and given in a table. A large excess heat capacity extending from the lowest temperature to room temperature with a broad maximum at about 75 K was found in comparison with the heat capacity calculated from those of pure zirconia and yttria on the basis of simple additivity rule. The shape of the excess heat capacity is very similar to the Schottky anomaly, which may be attributed to a softening of lattice vibration. The amount of the excess heat capacity decreased with increasing yttria doping, while the maximum temperature did not vary. The relationships among the excess heat capacity, defect structure and interatomic force constants, and also the role of oxygen vacancy were discussed.
Authors:D. Sedmidubský, J. Leitner, P. Svoboda, Z. Sofer, and J. Macháček
The low temperature heat capacities of three AIIInitrides, AIII=Al, Ga and In, were measured by relaxation method in the temperature range 2–300 K and the corresponding entropies at the
reference temperature 298.15 K were evaluated from the experimental data. The lattice heat capacity at constant volume was
also assessed theoretically within harmonic crystal approximation by direct method using a combination of VASP software package
to obtain the Hellmann-Feynman forces and the Phonon program to calculate the phonon spectra. The experimental data were analyzed
by means of a Debye-Einstein model taking use of the calculated heat capacity and involving additionally an anharmonic contribution.
Authors:V. Drebushchak, Yulia Kovalevskaya, I. Paukov, and Elena Boldyreva
Heat capacity of tripeptide diglycylglycine was measured in a temperature range from 6.5 to 304 K. The results were compared
with those for glycine and glycylglycine. Peptide bonding was found not to change CP(T) virtually above 70 K, where heat capacity does not obey the Debye model.
Comparison with literature data allows one to expect a significant difference in the heat capacity for enantiomorph and racemic
species of valine and leucine, like it was found recently for D-and DL-serine.
Authors:V. Drebushchak, Yulia Kovalevskaya, I. Paukov, and N. Surkov
Synthetic enstatite MgSiO3 was crystallized from a melt, quenched into water, and then annealed at 873 K. The product is the monoclinic polymorph with
the unit cell parameters of a=0.9619(7), b=0.8832(3), c=0.5177(4) nm, β=108.27(5)°. Heat capacity was measured from 6 to 305 K using an adiabatic vacuum calorimeter. Thermodynamic
functions for clinoenstatite differ by about 5% from those predicted after a thermodynamic model in the literature, but are
very close to those measured for orthorhombic enstatite.