Termite resistance is one of the important wood properties of sugi. However, few studies have examined variations of termite resistance among sugi cultivars. In many previous studies, sugi heartwood extractives were identified and quantified, but few studies examined the distribution of extractives in xylem cells. In this study, we examined the termite resistance of sapwood and heartwood of Obi-sugi cultivars (sugi cultivars planted in southern Kyushu, Japan) and compared the termite resistance with that of the other sugi cultivars (Yabukuguri and Kumotoshi). We also tried to observe the distribution of extractives in xylem cells with a confocal laser scanning microscope (CLSM) by selecting the excitation/emission combination of wavelengths of lasers (Ar and HeNe). There was a significant difference of termite resistance of heartwood among Obi-sugi cultivars. However, the heartwood of Obi-sugi cultivars with greater termite resistance had the same termite resistance as the heartwood of the other sugi cultivars. The sapwood of Karatsuki (one of the Obi-sugi cultivars) had greater termite resistance than the sapwood of the other sugi cultivars. The extractives observed with a CLSM (excitation/emission combination: 488nm/520-576nm) (extractives A) were mainly distributed on the cell wall of tracheids. The extractives observed with a CLSM (excitation/emission combination: 633nm/638-642nm) (extractives B) were mainly distributed in the lumen of tracheids. There were larger amounts of extractives B in heartwood than in sapwood. In heartwood of the cultivars with great termite resistance, there were larger amounts of extractives B, especially in the cell wall of tracheids.

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In the present study, the sound insulation of three-layered walls composed of cedar timber and plywood were measured and evaluated in accordance with JIS A 1416 and JIS A 1419-1, and they were compared with those of conventionally constructed walls. Two types of three-layered walls were investigated: symmetrically bound walls, whose front and back layers are composed of plies of equal thickness, and asymmetrically bound walls, whose front and back layers are composed of plies of unequal thickness. The following results were obtained. Asymmetrically bound three-layered walls provide better sound insulation in low and middle frequency ranges than symmetrically bound three-layered walls. The coincidence effect in three-layered walls in the range of 2000-3000Hz is less than that in two-layered walls. Three-layered walls are good sound insulators, and the insertion of glass wool has little effect on their sound insulation and The insertion of an air layer has little effect on the sound insulation of three-layered walls whose layers have the same surface density and same material composition.

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In order to correlate bonding durability obtained from accelerated aging tests (AAT) and outdoor exposure tests, and to investigate the influence of wood preservatives, resorcinol content, specimen width and specimen density on bonding durability of glulam, we manufactured 5 ply sugi glulams with laminae treated with five wood-preservatives (ACQ, E-NCU, E-CUAZ2, NZN, AAC). Block shear form specimens of 10mm and 25mm width were taken from those glulams, and specimens were subjected to cyclic-boiling (C-B) or cyclic-vacuum-pressure (C-VP) of 2, 5, 10, and 20 cycles respectively, followed by block shear tests. We defined the wood failure area for which we could not confirm an adhesive layer as “deep wood failure”, and calculated the deep wood failure ratio. The decrease of shear strength at C-B was larger than that of C-VP. The results of statistical tests showed that the degree of decrease of shear strength did not correspond to the differences of shear strength observed among wood preservatives. Though shear strength of 25mm width specimens showed higher values than those of 10mm width before AAT, after AAT 10mm width specimens showed higher values and less decrease of shear strength than those of 25mm width. It was assumed that the reason was that stresses occurring at the adhesive layer or wood for 10mm width specimens were lower than those for 25mm width. High density specimens showed higher shear strength before AAT; however, those differences tended to diminish after AAT. In most cases phenol⋅resorcinol resin adhesive showed higher shear strength than resorcinol resin adhesive. Wood failure ratio did not show remarkable differences, and deep wood failure ratio increased remarkably after two cycles of AAT.

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Using Hypsizygus marmoreus (Peck.) Bigelow, the effect of the addition of larch charcoal on mushroom cultivation was examined. Charcoal addition to sawdust-rice bran medium promoted mycelial growth, which reached a maximum when the amount of charcoal was raised to 10% of the culture medium. In contrast, fruit body yield was not influenced by the addition of charcoal. The total cultivation period was shortened by 7-10 days, as estimated from the acceleration in spawn running. Taken together, the results show that the addition of larch charcoal to culture medium is an effective way of shortening the total cultivation period of H.marmoreus.

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Impregnation with urea and glycol compounds under pressure (DS treatment) is an easy treatment for the dimensional stabilization for green wood. To clarify the effects of DS treatment, we examined the deformation of treated Japanese cedar boxed-heart timber during drying. As a result, the anti-shrink efficiency (ASE) of the DS treated specimens was about 33% in the T direction under both air-dried and oven-dried conditions. This effect reduced the occurrence of cracks, and the shrinkages in the T and R directions were nearly equal because the DS specimens had dried while maintaining their square shapes. Then, we applied a color reaction chemical to the cross sections of the air-dried specimens, and calculated the area of the part penetrated with DS chemical. As a result, within 50mm from the end those parts were completely penetrated, and beyond 50mm they were partially penetrated from the surface to a depth of 15mm. There was a high correlation between penetration and anti-shrink effects. By the above explains we clarified the dimensional stabilization effect of DS treatment for practical size timber.

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Material characteristics of large diameter sugi logs grown in Miyazaki and flat squares sawn from them were investigated and their bending performances were examined. Modulus of elasticity from longitudinal vibration (E_t) of first logs was about 19% lower than that of second logs. However, modulus of rupture in bending (MOR) was only 2% different between lumber without pith sawn from first logs by taper rule sawing and lumber with pith sawn from second logs by center rule sawing, and the difference was not significant. In relationships between E_t of logs and E_t of flat squares, E_t increased only 2% for lumber with pith obtained from second logs, while E_t increased 25% for lumber without pith obtained from first logs. It shows that taper rule sawing is an effective method to improve the bending performances. Also, it shows that its effect easily appeared in logs with lower E_t and larger taper rate (T_r).

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