This study aimed to clarify the factors that influence tree susceptibility to infection by the white-rot fungus Perenniporia fraxinea, by inoculating it into stems of four tree species at butt and breast height, and comparing the alterations in the xylem three to five months after inoculation. The four tree species include Robinia pseudoacacia, Cerasus sargentii, Ulmus davidiana var. japonica and Picea glehnii; the former two species are easily infected by this fungus, whereas the latter two species are not. Polymerase chain reaction (PCR) analysis detected the inoculated fungus only in the butt xylem of R. pseudoacacia and C. sargentii and the cell walls in the butt xylem tissues of these species were eroded by hyphae. Other xylem alterations (e.g., water accumulation and cell occlusion) differed among tree species, whereas no apparent difference was observed between butt and breast height. For example, water accumulation occurred in the discolored wood tissues around the inoculated holes in both R. pseudoacacia and U. davidiana var. japonica, while dehydration occurred in the light-colored wood tissues around the inoculated hole in P. glehnii. In the vicinity of the inoculation holes, resin deposits formed in P. glehnii, whereas cell occlusions by tyloses/gums occurred in the other three species. These results suggest that susceptibility to P. fraxinea infection differs not only among tree species but also between heights above ground. It is likely that no particular response to fungal inoculation in the xylem tissues of these four tree species is closely associated with their susceptibility to the infection by P. fraxinea.

Sugi five-ply glued-laminated-timbers (GLT) were manufactured using 3 resorcinol resin adhesives, 3 water-based-polymer-isocyanate resin adhesives, and vinyl-acetate emulsion adhesive (VAE). GLTs were treated with wood preservative, ACQ (Alkaline Copper Quaternary), and exposed under outdoor conditions with their glue-layers positioned horizontally for ten years. After one, three, five, and ten years of exposure, block-shear test were conducted and deterioration of GLT according to position was investigated. Residual ratio of shear-strength increased in order of south-side, north-side, and middle of south-side and north-side positions. Deterioration rates of shear-strength at south-side were larger than those at north-side. Decrease and deterioration rate of shear-strength were large at upper glue-layers, and this was conspicuous in VAE with low adhesion durability. Wood-failure ratio decreased at the first glue-layer of VAE after five year of exposure. However, in other adhesive resins, differences of wood-failure ratio among position or glue-layers were small regardless of exposure duration.

The deodorant effects of neutralized pyroligneous liquids were chemically studied to investigate their deodorant mechanisms. Three pyroligneous liquids, which were obtained from nara (Quercus serrata Thunb. and/or Quercus crispula Blume), ubamegashi (Quercus phillyraeoides A. Gray), and mosochiku (Phyllostachys pubescens Mazel), respectively, were neutralized with sodium hydroxide, and then their deodorant activities were examined. Five typical offensive odor compounds, ammonia, trimethylamine, hydrogen sulfide, methyl mercaptan, and acetaldehyde, were used in the deodorant tests. All of the neutralized pyroligneous liquids had clear deodorant effects on ammonia. Although all three of the neutralized pyroligneous liquids exhibited deodorant effects against trimethylamine, the effects of the pyroligneous liquid from ubamegashi were markedly decreased by neutralization. The deodorant effects of the three pyroligneous liquids on hydrogen sulfide were considerably increased by neutralization. The pyroligneous liquids from nara and mosochiku exhibited greater deodorant effects against methyl mercaptan after being neutralized. Finally, acetaldehyde emission was markedly inhibited by the addition of sodium hydroxide to the pyroligneous liquids.

Ultraviolet wavelength short pulse laser (UV laser) was used to apply microscopic incisions to wood surfaces. Using the incisions, we tried to improve the physical properties by plasticizing the surface layer by impregnating it with resin. The UV laser can make a large number of perforations without impairing the aesthetic appearance of wood. Focusing on this point, at an incision treatment of 667 holes/cm², resin penetration was obtained up to the hole depth from the laser, even with a coating operation under atmospheric or a slightly reduced pressure, and a remarkable improvement in physical properties could be confirmed. When using acrylic resin, the rate of impregnation of solid content was 66 and 53% for sapwood of Japanese cedar and heart wood of Japanese larch, respectively, and the Brinell hardness was improved more than 6 and 4 times, respectively, and the indentation depth in the impact test was decreased less than 1/4 for both specimens. Although a high rate of impregnated solid content could not be obtained, a certain improvement in performance was observed even when a common resin coating was applied for treatment.