Molecular Orientation of Carboxylic Acids Adsorbed on Graphite from the Liquid

We present calorimetric and incoherent elastic neutron scattering data from simple monocarboxylic acids, nonanoic (C9) acid, tetradecanoic (C14) acid and hexadecanoic (C16) acid, adsorbed from their liquids to the graphite surface which indicate the formation of solid monolayers with molecules which are predominantly upright.

(by A. Inaba)

Melting of Two-Dimensional Solids
at Gas-Solid and Solid-Liquid Interfaces

The 2-D molecular solids of various molecules including alkanes formed at an interface of the bulk liquids and graphite melt above the bulk melting temperatures, whereas the 2-D solids formed on the surface of graphite melt well below the bulk melting temperatures. It is considered that the 2-D solids at gas-solid interface melt to form the 2-D liquids, whereas the 2-D solids at solid-liquid interface melt to form the bulk liquids.

(by A. Inaba)

Low-Temperature Heat Capacities and Glass Transitions of Cross-Linked Lipase Crystal – Water Systems

The heat capacities of cross-linked lipase crystal – water systems with water content of 58.7, 29.2, 11.4, 5.8, and 0%. The quenched crystals with 58.7 and 29.2% water content exhibited a glass transition around 170 K. An exothermic effect due to the crystallization of supercooled water and a fusion of ice was found above 200 K and around 270 K, respectively. The samples annealed around 220 K until the exothermic effect disappeared also showed a glass transition around 170 K. The crystals containing 11.4 and 5.8% of water gave rise to only a glass transition at about 190 K. In the dried crystal, a small thermal anomaly due to impurity was observed above 200 K in spite of dialysis. The amount of bound water was determined to be about 0.27 g per gram of lipase. The water content dependence of the glass transition temperatures revealed that the glass transitions are attributed to the freezing of the cooperative motion between the lipase and the bound water molecules.

(by Y. Shimizu & Y. Miyazaki)

Low-Temperature Heat Capacities and Glass Transitions of Lipase – Water Systems

The heat capacities of lipase – water systems with water content of 58.2, 34.5, 15.5, 8.7, 5.8 and 0% were measured. The samples contained 58.2 and 35.4% of water showed a broad glass transition around 150 K and melting of ice around 270 K, while the samples containing 15.5, 8.7, and 5.8% of water showed only a broad glass transition. The fully dried lipase did not show any thermal anomalies. From the enthalpy of melting of ice, the amount of the bound water was determined to be 0.29∼0.30 g water / g protein.

(by K. Kikuchi & Y. Miyazaki)