This paper describes the applications of synthetic diamond products, which accounted for more than 97% of the world's annual consumption of diamond in technical sectors for 1992. They have provided a wide, and may probably provide a wider range of applications due to their mechanical properties properly controlled by process parameters, as well as the surface modification techniques which have been developed remarkably in these years.

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Polycrystalline cubic boron nitride (pcBN) materials, which are produced by sintering cBN powder and binder material under ultra-high pressure and temperature conditions, have so high hardness, high thermal conductivity and very weak affinity for ferrous metals that pcBN has been used for cutting ferrous metals such as hardened steel, cast iron, powder metal heat resisting alloy or roll. In order to improve machining efficiency or accuracy, hard turning by pcBN material has been introduced instead of grinding process. High-speed cutting cast iron with pcBN material is one of the most important applications to reduce the production cost. pcBN also shows more excellent cutting performance than other tool materials for powder metal, heat resisting alloy and roll. This paper discribes the characteristics and the application examples of pcBN materials.

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This paper provides the outline of cBN in its synthesis, production, properties, application and market. Owing to the progress in generating high pressure - high temperature technique, various type of cBN grain can be produced and used as high performance material.

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Pressure and temperature effects on the structure and hydrogen-bonding of H₂0 ices are summarized. Recent progress on the pressure-induced crystal-amorphous and amorphous-amorphous first-order transitions of H₂O is also breifly reviewed and polymorphism in liquid water near the glass-transition temperature is discussed.

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Recent studies on behaviors of Escherichia coli and yeast at 10- 40 MPa where these microorganisms can survive were summarized. The aspects covered are, 1) abnormal elongation of Escherichia coli cell by application of high pressure, 2) correlation between hydrophobicity of the cell surface of E. coli and drug susceptibility under high pressure, 3) stress response of yeast (induction of various tolerance by heat shock and drug shock in yeast), and 4) pressure reversal of alcohol effects on the growth of yeast and its application to alcoholic fermentation under high pressure.

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Materials consisting mainly of cage structures or clusters are reviewed. These materials are now of high interest because they are expected to have hierachical electronic structures and should have novel properties as has been shown in fullerene - based materials.

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The property of its supercritical water can be changed remarkably by controlling its temperature and density. Application of its characteristics may make possible the decomposition, liquefaction and/or alteration of coal and other heavy fossil fuels, and the removal of sulfur, nitrogen, heavy metals and so on. In this report, decomposition treatments for liquefaction of coal in supercritical water are reviewed. Result of other fossil fuels such as oil sands are also presented.

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Fluid alkali metals are typical examples of materials whose electronic structures depend strongly on the thermodynamic state of the system. The most striking manifestation of this state dependence is the metal - nonmetal transition which occurs when the dense liquid evaporates to the dilute vapour or when the fluid is expanded by heating to its liquid - vapour critical point. The paper discusses equation of state data, electrical, and optical properties, and neutron scattering measurements of S ( Q) and S ( Q, ω) with special emphasis on the change in these properties in the metal - nonmetal transition region. The shape of S ( Q, ω) changes considerably on approaching the transition from the high - density liquid side, indicating a change in the interparticle interaction and the molecular structure. S (Q, ω) of rubidium in the density range between the melting point density and three times the critical density is characterized by the existence of well defined acoustic - phonon - like collective density excitations at high momentum transfer, whereas S (Q, ω) at a density of about twice the critical density is consistent with excitations of an optic - type mode in which two species tend to move in opposite directions.

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A bellows assembly is designed to drive diamond anvils and connected to the regulated helium gas pressure source. This permits horizontal optical access to the diamond-anvil core. The sample pressure can be changed remotely while the sample is maintained at operating low temperature.

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Recently shock compression technology has been bocoming popular in the field of materials science and geophysics in Japan as a tool of high pressure generation . A project research “Understandings of Shock Wave Phenomena” supported by Grant - in - Aid for Scientific Research of Ministry of Education, Science and Culture, Japan has been conducted in 1990- 93. An im -portant topic of this project was shock wave phenomena in condensed matters. A recent activity of the research on condensed matters is summarized and an importance of quantitative re -search of shock temperaure in porous materials is emphasized .

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