This article reviews recent high-pressure Raman and Brillouin studies of hydrogen-bonded molecular crystals. Results on selected materials, with a view to illustrating the high-pressure physics for the hydrogen bond, are presented and discussed: HF as the one-dimensional hydrogen-bonded system, HCONH₂ as the two-dimensional system, H₂O as the three-dimensional system, and H₂S as the hydrogen-bonded system in the plastic phase.

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Recent high pressure and high temperature in situ X-ray experiments using synchrotron radiation are reviewed. Among them are the behavior of Fe-H system, the conversion of graphite into hexagonal diamond, and an in situ observation of the formation of MgSiO₃ perovskite from enstatite. The latter two studies were made by the newly developed Drick-amer-type high pressure apparatus using sintered diamond anvil, which is capable up to at least 30 GPa and 1500°C. Experiments up to 210 GPa were performed using diamond anvil apparatus combined with a very thin collimator system. A design of the apparatus to be constructed in the new synchrotron facility is discussed.

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Application of computer experiments to fluids and fluid mixtures is described. General introduction to the molecular dynamics (MD) and Monte Carlo (MC) methods is given and the importance of intermolecular potential functions is stressed. Two types of potential functions have been used to simulate fluid mixtures. The first one is represented dy the Lennard-Jones (LJ) potential. Thermodynamic and phase behavior of LJ fluids and their mixtures is examined in detail. Some fluid systems such as water and aqueous solutions are shown to be simulated by using specific potential models based on quantum mechanical molecular orbital calculations.

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First, the historical development of high pressure NMR for solution studies has been reviewed; it has been started by Benedek-Purcell, developed extensively by Jonas, and expanded further by Yamada and some others in several countries with different purposes as a versatile tool for studying structure, phase transitions, dynamics, and reactions at high pressure. Second, the characteristic features of modern NMR spectroscopy are described. Third, the new high pressure NMR machine, recently constructed by the Research Grant-in - Aid for the Priority Area of Nonequilibrium Processes in Solution, has been illustrated, together with the reliability test and some experimental results on the spin - lattice relaxation time for heavy water. Fourth, it is confirmed that the rotational relaxation time is sensitive to the water structre due to anisotropic hydrogen bond interactions.

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The application of high pressure technology to food processing and bioscience is a current topic. Water is the main component in such multicomponent systems to control their macroscopic properties and function. Under high pressure, water is not only the medium propagating pressure, but also it affects the stability and function of biopolymers through the modification of hydrogen bonds, hydrophobic and electrostatic interactions. This review is devoted to demonstrate how the biopolymer-water interaction (hydration) is related to the pressure effects on its structural stability, focusing on the compressibility, pressure denaturation, and gelation of proteins.

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Pressure can be a key control factor in the applied enzymology. High pressure technique can be introduced in many aspects of enzyme engineering; preparation of enzymes, enzymatic conversion of chemical substances, modification and alternation of enzyme functions in chemical or biochemical ways, and enzymatic (biochemical) processes including immobilized enzymes. It could be called as high pressure enzyme engineering. Among these, the utilization of pressure dependence of enzymatic reaction rates and of the pressure-induced change in the higher order structure of enzyme proteins are explained in detail, by taking some hydrolytic enzymes as the examples.

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Although the deep - sea environment with high pressure and low temperature is rigorous for microorganisms in costal water, many barotolerant and barophilic bacteria are found to be inhabiting there. It is very important for the barophilic or barotolerant bacteria to maintain the physiological functions of cell membrane, because many vital functions are involved in the membrane. The fluidity of membrane composed by phospholipids and proteins is essential for the physiological functions. As high hydrostatic pressure raises the melting point of lipids and causes the phase transition of lipid within 100 MPa, barotolerant bacteria under high hydrostatic pressure appear to regulate the fluidity of membrane phospholipids. Therefore, the characterization of membrane at high pressure is indispensable to clarify the biochemical adaptation of bacteria to the environment. This report dealt with effects of pressure and temperature on the lipid composition of barotolerant deep - sea bacteria. The bacteria maintained the membrane fluidity by increasing unique fatty acids under high hydrostatic pressure.

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JAMSTEC, in order to effectively promote research and development of the deep-sea environments, inaugurated a new “Deep-sea Environment Exploration Program (DEEP) ” in October 1990. The new program, launched following the completion of a world-class submersible, the “SHINKAI 6500” and its support vessel “YOKOSUKA” (4500 tons), and based on JAMSTEC's past deep-sea research experience, reflects our growing interest in studying the deep-sea more analytically, one step forward from the “descriptive”-type research that we have traditionally been engaged in. The DEEP will enlist the services of the researchers on contract with JAMSTEC and organize them into respective study groups to pursue basic and pioneer-type research. In order to support research activities of the DEEP, JAMSTEC has been engaged in developing the “Deep-sea Microorganisms Collecting - Cultivating System (DMCCS) ” as a four-year plan starting 1990. Under the system, specimens will be collected and kept in the same environmental conditions (pressure and temperature) in which they naturally grow. Then they will be diluted, isolated and cultured in facilities built on the ground and kept in an environment equivalent to deep-sea. The DMCCS consists of four subsystems ; the sediment sampler, dilution device, isolation device, and culture vessel.

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CFCs regulation has been accelerated in association with recent findings of ozone depletion. HCFCs, which are being investigated as alternatives to CFCs, will also be eventually regulated althoghu it will be difficult to identify satisfactory environmentally acceptable alternatives. Research and development on alternatives of zero ODP should be undertaken now. HFCs are considered as one of the next generation alternatives. This paper will present properties on HFCs and their mixtures such as general properties, flammability, solubility, stability, material compatibility, and cycle performance, including informations on CFCs and HCFCs regulations and up - dated results on AFEAS and PAFT.

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