Supercooled water, aqueous solutions at low temperatures and their glassy states are closely related to cryopreservation of living cells, foods, and related materials. The studies we have conducted are mostly basic and relevant indirectly to cryo-biological technology. They are roughly divided into three groups: (1) The works intended to interpret anomalous properties of supercooled water, (2) Raman and DTA studies of aqueous solutions at low temperatures and their glassy states, and (3) Basic researches of cryo-preservation of plant-cells by vitrification. In the (1) group, an X-ray diffraction study of supercooled water was carried out and it is concluded that clathrate-like structures increase with decreasing temperature. The location of the second critical point of water is estimated to be T_<c2> < -100℃ and P_<c2> = 〜200MPa. In the (2) group, there are many Raman studies devoted to glassy aqueous solutions. It is found that ionization of sulfuric acid increases with decreasing temperature. In the DTA studies for supercooling behavior of aqueous solutions, it is confirmed that the linear relation between melting temperature (T_m) and homogeneous ice nucleation temperature (T_H) holds quite well for many aqueous solutions. In addition, the additivity rule is found to hold in the supercooling of aqueous solutions. In the (3) group, many measurements were made on the T_H values for various types of aqueous solutions as a function of pressure. From the observation that pressure accelerates supercooling and vitrification of an aqueous solution, we made preliminary experiments to preserve carrot cells at high pressure.
