Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is a powerful technique that provides chemical information about the surface of a solid sample and does not need any pretreatments. The significant advantage of ToF-SIMS over other techniques is imaging analysis, which allows the direct visualization of the chemical distribution on the sample surface with submicrometer spatial resolution. Here the applications of ToF-SIMS to wood science are discussed. Recent studies showed that ToF-SIMS is a useful tool for the structural analysis of lignin by detecting the monomeric ions which correspond to its structural units (guaiacyl and syringyl types). Several ToF-SIMS studies that examined pulp fiber surfaces or properties of paper have been reported. ToF-SIMS has also been used to investigate the distribution of heartwood extractives.

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We examined the rooting of viviparous seeds of Kandelia candel planted at different depths, as a part of the basic studies aiming at mass production of seedlings for efficient afforestation of mangroves. Shoot elongation of the viviparous seeds was promoted by increasing the depth of planting, which is in agreement with previous reports on the rooting of deeply planted cuttings of Viburnum awabuki and Prunus persica. However, in the lower part of the viviparous seeds where the root primordia existed before planting, the depth of planting influenced neither the part nor the number of rootings. On the other hand, in the upper part of the viviparous seeds where the root primordia appeared after planting, the rooting part was expanded and the number of rootings increased by deep planting. These results suggest that the contact of the upper part of the viviparous seeds with the culture medium at the time of planting stimulated the formation of root primordia in the upper part. In addition, no rooting part was found at approximately 2 cm between the upper part and lower part.

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A very important problem that cannot be overlooked is the occurrence of long term relaxation on the contact stress and creep of Japanese traditional joints. This research to gain understanding and improving creep of Kanawa-tsugi (Japanese traditional beam to beam joint), was focused on improving the degree of coupling in the joint by the recovery property of compressed sugi komisen (wooden square key) by introducing compressed sugi as the komisen material. It was verified that the joint with compressed komisen inserted showed less relaxation of the contact stress. It maintained over 59% of initial stress to the last cycle even though being exposed to cyclic humidity change (shirakashi komisen : 19%). Also, the creep of compressed sugi komisen by influence of cyclic humidity change was relatively lower than that of shirakashi one. It was concluded that compressed wood gives good performance as a type of key or wedge fastener and it maintains large cross-direction stresses due to its low stress-relaxation in company with its recovery property.

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To predict the strength properties of timber joints composed of compressed LVL plates and compressed LVL pins, slip moduli and yield loads of the joints were calculated by the theory of a beam on an elastic foundation and the European yield theory, and joints with six kinds of glulam were tested in shear. At the compression-type lateral strength test of compressed LVL joints, first the compressed LVL pin yielded by bending and the load fell once (Stage 1), and then the load recovered and increased when the pin became embedded into the glulam (Stage 2). The slip modulus and the lateral resistance of the joint increased with increasing density of the glulam. The joint model of Stage 1 was a three-member double shear joint with timber center and side members, and that of Stage 2 was a two-member single shear joint with a virtual timber-to-timber connection at the center of the member. In Stage 1, the slip modulus of the joint and the yield load of the pin calculated by the theory of a beam on an elastic foundation showed significant correlation with experimental values. In Stage 2, the yield load of the glulam calculated by the European yield theory showed significant correlation with experimental values.

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Six wood species were exposed to UV and visible light (278 nm to 496 nm) with narrow band gaps (20 nm), and the effects of wavelength on their discoloration patterns were investigated. Light-colored wood specimens (L^* ≥ 70, a^* < 8) underwent photo-darkening and photo-bleaching when exposed to light in the UV and visible range, respectively. The wavelength at which such transition from photo-darkening to photo-bleaching occurred, however, varied among wood species and tended to be longer for softwood than for hardwood. Discoloration patterns of dark-colored wood specimens (L^* < 70, a^* ≥ 8) were much more complicated, whereas these patterns shifted slightly toward those observed for light-colored wood after extraction treatment. There was a tendency for initial color of wood species and their discoloration patterns : the smaller the initial L^* value was, the shorter the wavelength at which the darkening/bleaching transition occurred for L^* ; the larger the initial a^* value was, the shorter the wavelength of the darkening/bleaching transition for a^* ; and there was no obvious tendency for b^*.

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