Due to human activities of mass-production, mass-consumption and mass-waste, environmental issues such as global warming and acid rain have become increasingly serious in the world. In such environmental situations, biomass resources, which are renewable, carbon-neutral and remarkably abundant on earth, are becoming important as an alternative to fossil resources. For the chemical conversion of biomass resources, on the other hand, supercritical fluid has recently received attention as a new reaction field due to its unique properties. In this paper, therefore, current progress in research and development of environmentally benign supercritical fluid technologies is introduced for the chemical conversion of lignocellulosics into valuable liquid fuels and chemicals.

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Tracheid arrangements and shapes on transverse sections were reconstructed by use of Fourier transform image analysis in five families, fifteen genera, and twenty-two species of softwoods. Each maximum tangential diameter of the reconstructed models was equal to the respective average value of Feret's tangential diameter measured by ordinary accumulated image analysis. By that result, the model's properness was confirmed. The distance between radial files could be regarded as the standard size peculiar to each species. A standard size model was made, in which both radial and tangential lengths were equal to the standard size. At the same time a standard hexagonal model that had minimum periphery was formed. A reconstructed model was normalized by the difference from the standard hexagonal model. The radial enlargement and the invasion ratio in tangential direction were calculated by normalization. The length ratio of radial walls to tangential walls was calculated from the reconstructed models. The former was about 1.4 times as large as the latter on average. The alternate ratio that expresses cell arrangement between radial files showed that almost all species had imperfectly alternative arrangements. Characteristics of each species could be analyzed quantitatively by use of these parameters.

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Sugi (Cryptomeria japonica D. Don) boxed heart timbers from Miyazaki prefecture were kiln-dried at low humidity under two high-temperature conditions. The distribution of moisture content, changes in moisture content and the generation of internal checks were examined. Our findings are summarized as follows :
1) In the examination with an intermediate period of steaming, a large difference in moisture content was observed depending on green timber weight. Each layer of timbers of 34 to 36 kg had a moisture content of about 6%, and layers of timber of 37 to 39 kg had a final moisture content ranging from about 6 to 40%.
2) In the examination with a surface-drying stage at a dry-bulb temperature of 75°C and a wet-bulb temperature of 68°C, variation of moisture content in the cross section were almost equalized during the steaming process that followed this stage.
3) The amount of moisture content reduction per hour during drying at a dry-bulb temperature of 120°C was about equal at 1.2 to 1.6% for both drying methods.
4) Internal checks seemed to be generated near moisture content of 30 to 40%.

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We investigated the deformation behavior of wood being pressed perpendicular to the grain and the bending properties of the wood after pressing. Sugi (Cryptomeria japonica D. Don) flat-sawn timber prepared with various dimensions and moisture contents was compressed by a roller press or a platen press. The strain distribution and shear flow of the specimen surface under an applied load were measured by an image analysis method. The results showed that a large compressive strain was concentrated in the outer surface layer of the specimen by roller pressing, and shear strain occurred by roller pressing. This trend was intensified when the contact angle between the roller and the specimen was increased, and the trend was weakened in wet conditions. Forward slip was observed on the side of the specimen. The reason this phenomenon occurred only when using roller press was that the surface layer of the specimen was shear-deformed toward the tail end.
The bending properties after roller pressing decreased in inverse relation to the contact angle. On the other hand, the bending properties did not change when the contact angle was small. The specimen retained their bending properties when compressed at the contact angle that is lower than the point at the intersection of the lower limit of the 95% confidence interval for uncompressed specimens with the approximated line for all compressed specimens.

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Internal strains in sugi (Cryptomeria japonica D. DON) boxed-heart square timbers were measured by using strain gauges during high temperature drying above 100°C. We discuss relationships between internal cracks and strains during high temperature drying of two specimens 120 cm in length. The results obtained were as follows :
1) Internal cracks occur radially at each corner of the square cross section of the timbers.
2) The steep increase of the internal shrinkage may be attributed to the relief of tensile stress owing to the formation of cracks.
3) It is surmised that the first internal crack can occur within about 30 hours after the beginning of high temperature drying, and after that internal cracks may occur at the other corners of the square cross section.

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Built-up beams were made of two Sugi (Cryptomeria japonica D. Don) planks fastened together with wood pegs. In this study we investigated the edgewise bending properties of Sugi planks and 2ply built-up beams. 20 planks and 20 built-up beams were tested edgewise to destruction. The results are summarized as follows : 1) The modulus of elasticity (MOE) of planks in edgewise bending could be predicted well from the flatwise MOE of the same plank. 2) Modulus of rupture (MOR) and deflection at maximum stress of the planks were affected by MOE and edge-knot diameter ratio. 3) The MOE of built-up beams was very close to the average of the two MOE values of the component planks. Especially if the plank pairs are combined in taking account of the MOE distribution of planks, the variation in MOE of built-up beams can be reduced. 4) The average values of MOR and stress at proportional limit (σ_p) of built-up beams were lower than those of planks. However, the lower 5 percent exclusion limits for MOR and σ_p of built-up beams were approximately equal to those of planks.

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Heartwood extractives of Sugi (Cryptomeria japonica D. Don) had large variations among clones and high broad-sense heritability. Genetic improvement by selection of clones having large quantities of heartwood extractives was suggested to be possible. The heartwood had higher carbon content, larger variations among clones as compared to the sapwood. However, it was confirmed that the carbon content did not vary greatly with clone or the part of wood. Broad-sense heritability in both heartwood and sapwood was high, which implied that carbon content had a strong inheritance.
It is possible that differences in carbon content among clones might be chiefly caused by the difference in the percentages of the major components. in addition, the heartwood extractives contributed to the carbon content in the heartwood. Clones with large sapwood extractives tended to have high heartwood extractives.

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