Heat capacity measurements have been performed for the monolayer of n-C8F18 adsorbed on graphite between 100 K and 200 K by adiabatic calorimetry to investigate a possible phase transition in the 2D solid as well as the 2D melting transition. The X-ray diffraction measurements were also made in the temperature range from 12 K to 190 K. The monolayer exhibits a phase transition at 169.7 K, just below the melting point of 173.3 K. The associated entropy for both anomalies is estimated to be 18 J K−1 mol−1.
|
X-ray diffraction patterns obtained for the n-C8F18 monolayer on graphite, showing that there is a 2D solid-solid phase transition between 165 K and 170 K and a 2D melting between 170 K and 175 K. |
|
Molar heat capacity of the n-C8F18 monolayer on graphite. Since the 2D solid-solid transition at 169.7 K and the 2D melting at 173.3 K are close to each other, the enthalpy and entropy change are estimated for both together. |
Thermogenesis of fertilized eggs of the starfish, Asterina Pectinifera, was measured by isothermal microcalorimetry at T = 295 K. A variation of thermogenesis was attributed to synchronized cytokineses in the cleavage period. The heat of cytokinesis was evaluated to be ca. 9 μJ embryo−1. Residual thermal dissipation showed an onset in the vicinity of the 28 cell stage, in which mid-blastula transition takes place.
|
Photo 1. Embryos of Aterina Pectinifera in the 24 cell stage. |
|
Fig. 1. Thermogenesis of the eggs. Matured eggs were fertilized at t = 0, and 87 eggs were loaded in the microcalorimeter at t = 3 hr. Sequential peaks were attributed to the fifth to the eleventh cleavage. |
|
Fig. 2. Heat of cytokinesis was tentatively separated. The residual shows an onset in the vicinity of the 28 cell stage, in which mid blastula transition (MBT) takes places. |