Fibrous carbons, such as carbon fibers and activated carbon fibers, have valuable functions as industrial precursors for the production of carbon fiber-reinforced plastics, adsorbents and so on. Approaching global environmental issues are leading toward the utilization of biomass-derived carbonaceous materials to replace the current petrochemical-based industry. Woody biomass is comprised of multiple components resulting from highly complex metabolic systems. It is therefore more difficult to produce functional carbonaceous materials directly from woody biomass as compared to fossil resources. These disadvantages of the direct utilization of woody biomass have promoted approaches to establish effective systems for biomass refining into its components, and even to develop new functionalities for biomass carbons with defined differentiation from fossil-based carbons. In this review, current developments of woody biomass-based fibrous carbons are introduced.

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Longitudinal changes of dynamic modulus of elasticity values (E_fr) of logs for todomatsu (Abies sachalinensis) were investigated to clarify the best vertical region of the stem (height from ground level) to estimate its mean E_fr value, using plus trees and breeding stock. The relationship between stress wave velocity (V_p) of standing trees and E_fr of logs was also investigated to test the suitability of the stress wave propagation method for todomatsu. The longitudinal changes of E_fr of logs show similar tendencies within individuals for each clone. E_fr of the region from ground level to a height of 3 m could be used as an alternate value to the mean E_fr, and the region including breast height was appropriate for its genetic comparison between clones. Significant correlation between E_fr of logs and V_p of standing trees was obtained both in individuals and in clones. The correlation coefficients were especially high. Therefore it would be possible to estimate E_fr of logs in todomatsu based on the measurement of V_p of standing trees at breast height. This method will allow us to evaluate the wood quality of clones non-destructively.

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The effects of cell structure of bamboo on water adsorption were thermodynamically analyzed using the chemical potential change induced by restrained swelling. The potential was proportional to the product of moisture content and the bulk modulus of the restraining region in the woody tissue. Analysis results showed that layers in the cell wall of bamboo act to resist swelling so that the isotherm curve of the block and fiber sample, where thin crystal threads called microfibrils are wound helically in the circumference, was lower than that of woody tissue powder. These results are similar to those of wood reported previously.

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This research is focused on evaluating the efficiency and failure mechanism of joints using a komisen (Japanese traditional square key) of compressed sugi (Japanese ceder ;Cryptomeria japonica D. Don), and to evaluate to what extend hozo-komisen (Japanese traditional mortise and tenon) joint strength is being influenced by the recovery of compressed sugi komisen when exposed to long term humidity cycling.
Compressed sugi komisen showed a change of yield and rupture mode compared to shirakashi (Quercus myrsinaefolia Blume) komisen, as did the komisen inserting direction into the joint because it has characteristic and anisotropic properties. The compressed sugi komisen joint (C1R), when inserted according to the R-type, yielded by shear of the komisen and reached its maximum strength (P_max :12.5 kN) just before rupture at 10 mm displacement at the tenon. The failure mode showed a different pattern, compared to the shirakashi komisen joint (S1R) where the central komisen yielded in bending.
The strength of the compressed sugi komisen joint (C1RH) exposed to cyclic changes of humidity (40-80%RH) during two years increased in maximum strength, yield strength, and energy absorption. This is in contrast to the shirakashi komisen joint (C1RH) that showed a dramatic and remarkable strength decrease when exposed to the climatic environment.

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In order to study the recycling of waste gypsum boards, gypsum-bonded particleboards were manufactured by using the gypsum hemihydrate calcined from waste gypsum boards, and the mechanical properties of the particleboards bonded with recycled gypsum were examined. The amount of mixing water for the gypsum hemihydrate calcined from waste gypsum boards was high. However, the boards could be manufactured with the same amount of mixing water as reported for the pottery molding plaster in the previous paper because in the semi-dry type process it was not necessary to provide extreme mobility for the hemihydrate slurry. The mechanical properties of boards made from waste gypsum boards, such as the moduli of rupture (MOR) and elasticity (MOE) were improved. Also, the MOR and MOE values of the particleboards bonded with recycled gypsum containing the paper fibers were higher than those of boards where the paper fibers had been removed. It was found that the waste gypsum boards can be used as a raw material for gypsum-bonded particleboards.

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An asymmetric four-point-bending type shear test was developed to evaluate the shear strength of full-sized structural lumber. Medium dimension glulam made of sugi (Cryptomeria japonica D. Don) from Miyazaki prefecture was tested to confirm applicability of this testing method. Results obtained are summarized as follows :
1)It was found that partial compressive deformation at loading points prevented full-sized structural lumber from shear fracture when the shear strength of sugi specimens with low density grown in Miyazaki prefecture was evaluated by the three-point-bending type shear test.
2)Every glulam specimen tested by the asymmetric four-point-bending type shear test fractured neither by bending stress nor by partial compressive stress perpendicular to grain, but by shear stress. It was confirmed that using saddle-type steel jigs attached with lag screws was very effective in inhibiting partial compressive deformation at loading and supporting points.
3)The necessary number of lag screws could be estimated from the expression including shear stress, bending stress and partial compressive stress perpendicular to grain at loading and supporting points.
4)The average shear strength of medium dimension sugi glulam was 8.0 N/mm². This value was larger than the one obtained by the three-point-bending type shear test.

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To effectively utilize small diameter logs as a civil engineering material, the wood properties of such logs of hinoki (Chamaecyparis obtusa Endl.) were investigated by determining density of air-dried logs, pilodyn penetration, annual ring width, basic density and compression strength parallel to the grain. Logs of small diameter were collected from two stands of different ages and at different sampling positions in the trees :1)logs from 1.2 m height above ground of trees thinned in a 16-year-old stand, and 2)logs from treetops (about 18 m height above ground) derived from regeneration cutting in a 64-year-old stand. Logs from 16-year-old trees had only half the number of annual rings within logs compared with those from 64-year-old trees. Average values in basic density were 0.39 and 0.51 g/cm³, respectively. In both types of log, a significant negative correlation between pilodyn penetration value and basic density was found in the outermost part. Values of compression strength were greater for the 64-year-old trees than the 16-year-old ones. When small diameter logs are used as civil engineering materials for which high strength is required, it should be noted that strength properties of small diameter logs with almost the same diameter vary largely with age of trees and the position where the logs are collected.

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