Improvement of fiberboard made from acetylated fibers by ozonation I: effect of ozonation on mechanical properties

Acetylated fibers with a 24.8% weight gain by acetylation were ozonated with 0%–2.0% ozone on fibers. Fiberboards were then made from these treated fibers. The internal bond and bending strength of the acetylated fiberboards increased drastically with increasing ozone charge up to 0.5%–1.0%, whereas the thickness swelling of the fiberboards decreased. Ozone selectively cleaves the aromatic rings of hydrophobic lignin and introduces a hydrophilic carboxyl group into lignin. Thus, the wettability and thermoplasticity of acetylated fibers increased, and this structural modification improved the interfiber contact. Internal bond and bending strength increased as a result. In addition, steep density profiles were formed by the ozonation, resulting in high bending strength. The high compaction ratio accelerated the effect of ozonation. The optimum ozone charges for improving mechanical properties were 0.5%–1.0%.Part of this report was presented at the 49th Annual Meeting of the Japan Wood Research Society, Tokyo, April 1999     

Physicochemical properties and chemical compositions of <Emphasis Type="Italic">Melaleuca leucadendron</Emphasis> leaf oils taken from the plantations in Java,Indonesia

Melaleuca leucadendron Linn. leaf oils from Gunung Kidul, Gundih and Sukun, Java, Indonesia, at tree ages of 5, 10, and 15 years were analyzed to elucidate their qualities and chemical compositions. These oils gave yields from 0.61% to 1.59%. The samples from Gundih produced the highest yields (1.42–1.59%) compared to those from Gunung Kidul and Sukun. These oils were colorless with an odor typical of Melaleuca oils. The specific gravity of essential oils in this study ranged from 0.870 to 0.912. The samples from Gunung Kidul were the highest in specific gravity (0.905–0.912). The refractive index values of oil samples ranged from 1.468 to 1.470, optical rotation ranged from (−)2.47° to (−)0.98°, and ratio miscibility of oils in 70% ethanol ranged from 1:1 to 1:9.67. The organoleptic profiles and physicochemical properties of M. leucadendron Linn. leaf oils in this study were evaluated based on the Indonesian National Standard (SNI) 06-3954-2006 for standard quality of Melaleuca essential oils; only a few specific gravity values were below the standard. GC-MS spectrometry analysis indicated the presence of 26 compounds. Among them, 1,8-cineole (44.76–60.19%), α-terpineol (5.93–12.45%), d(+)-limonene (4.45–8.85%), and β-caryophyllene (3.78–7.64%) were the major components. Samples from each site tended to decrease in 1,8-cineole content and increase in β-caryophyllene content as plant age increased. α-Terpineol was highest at plant age 10 years, and d(+)-limonene varied according to plant site and age.     

Fire resistance of thick wood-based boards

Thick wood-based boards are used as construction materials for walls and floors in Japan. In this study, fire resistance tests (ISO 834-1) and cone calorimeter tests (ISO 5660-1) were conducted for thick plywood, particleboard, and medium density fiberboard with sample thicknesses of about 28–30mm, and their suitabilities for quasi-fireproof or fire-preventive structures were evaluated. In the ISO 834-1 fire resistance test, the heat-shielding performance (insulation criterion) for walls was evaluated and the results showed that the larger the apparent density of a woodbased board, the higher its insulation performance. The insulation performance of thick wood-based boards in the fire resistance test could be forecast from the results of the cone calorimeter test, especially when the second peak of heat release rate appeared. In the cone calorimeter tests, the surface layer density of the plywood, particleboard, and medium density fiberboard was the dominant parameter for the time to ignition and initial heat release rate. These results indicate that thick wood-based board is a suitable fire-preventive construction material. Part of this study was presented at the Annual Meeting of the Architectural Institute of Japan, Hokkaido, Japan, August 2004     

Discoloration induced by Raffaelea quercivora isolates in Quercus serrata logs and its relation to phylogeny: a comparison among isolates with and without the Japanese oak wilt incidence including outside of Japan

Japanese oak wilt (JOW) has been prevalent in Japan since the late 1980s. Infections of the fungus, Raffaelea quercivora Kubono et Shin. Ito, which is transmitted by an ambrosia beetle [Platypus quercivorus (Murayama)], can cause JOW. Although R. quercivora, P. quercivorus, and oak trees are distributed in other Asia–Pacific countries, the incidence of JOW has not been reported outside Japan. In this study, we collected R. quercivora isolates from 5 Asian countries, including Japan, and compared their ability to induce sapwood discoloration by inoculating Q. serrata logs. The tangential widths of the discoloration in sapwoods inoculated with non-Japanese isolates were equivalent to or greater than those of the 2 Japanese isolates. This indicates that a lack of JOW incidence outside Japan is not because of the lowered ability of R. quercivora to spread discoloration compared with the Japanese isolates. Statistical analyses of the relationship between discoloration and phylogeny based on DNA sequences of actin and chitin synthase showed that the discoloration width was independent of phylogenetic relatedness among the isolates. To discuss why the occurrence of JOW has not been reported outside Japan, further studies (e.g., on host susceptibility and P. quercivorus aggression) throughout Asia are needed.     

Dormancy release in male flowers of <Emphasis Type="Italic">Cryptomeria japonica</Emphasis>

To clarify key characteristics of the process whereby dormancy is released in male flowers of Cryptomeria japonica, twigs with male flowers were collected every three days between December 1992 and February 1993. Half of the twigs collected on each date were chilled at 0°C for three days and the cumulative temperatures required by the chilled and non-chilled flowers for florescence were compared. There was no difference in the cumulative temperature required for florescence between chilled and non-chilled male flowers collected before 19 December. However, for samples collected between 21 December and 21 January, the cumulative temperature needed for the florescence of chilled male flowers was 8–68°C lower than that required for non-chilled male flowers. However, there was little difference again in the cumulative temperature required to induce the florescence of chilled and non-chilled male flowers for collection dates later than 24 January. These results suggest that the dormancy of male C. japonica flowers was gradually released by exposure to low temperature and the process was completed by 24 January. The cumulative temperature required for florescence and the sum of the mean daily temperatures between the date of collection and the date of natural pollen dispersal were almost equal after the dormancy of the male flowers was released. The exact day on which pollen will be released can be predicted using the dormancy characteristics of male flowers.     

Temporal changes in litterfall, litter decomposition and their chemical composition in Sasa dwarf bamboo in a natural forest ecosystem of northern Japan

We investigated the dynamics of litterfall and litter decomposition of Sasa dwarf bamboo (Sasa senanensis) and trees to clarify the characteristics of organic matter and nitrogen cycling between plant and soil in a natural cool-temperate mixed forest ecosystem dominated by an understory vegetation of Sasa. Mean annual Sasa litterfall over the 3-year study period was 164 g m^?2 year^?1, which accounted for approximately 29% of total litterfall. Litter decomposition of Sasa leaf and Sasa culm was significantly slower than that of tree leaf during first and second years. The slow decomposition rates of both Sasa litter types were caused by a significantly higher silicate than in tree leaf. Nitrogen concentration in litter increased as decomposition progressed, especially in Sasa leaf and tree leaf. As a result of the slow decomposition of both Sasa litter types, 111 and 73% of nitrogen to the initial amounts were retained in Sasa leaf and Sasa culm after 3 years, respectively. The amounts of retained nitrogen in Sasa leaf, Sasa culm, and tree leaf after 3 years were 1.29, 0.47, and 3.92 g N m^?2, respectively, indicating that the differences of litter decomposition rates among the litter types influence on the nitrogen cycling in forest ecosystem through the differences of the nitrogen release from litter.     

Successive deaths of a captive snow leopard (Uncia uncia) and a serval (Leptailurus serval) by infection with feline panleukopenia virus at Sapporo Maruyama Zoo

Feline parvoviruses were isolated from frozen samples of intestines taken from a snow leopard (Uncia uncia) and a serval (Leptailurus serval) that died successively at Sapporo Maruyama Zoo in Hokkaido, Japan. Isolates possessed an antigenic epitope for both the feline panleukopenia virus (FPLV) and mink enteritis virus, identified with a hemagglutination inhibition test. Sequencing analyses of the VP2 region of the isolates revealed that the two isolates were identical and of the FPLV-type. These results suggested that FPLV was introduced from a feral cat which entered the zoo and transmitted the virus inside the zoo.     

Software development for estimating the concentration of radioactive cesium in the skeletal muscles of cattle from blood samples

The 2011 earthquake severely damaged the Fukushima Daiichi Nuclear Power Plant (FNPP), resulting in the release of large quantities of radioactive material into the environment. The deposition of these radionuclides in rice straw as livestock feed led to the circulation of contaminated beef in the market. Based on the safety concern of the consumers, a reliable method for estimating concentrations of radioactive cesium in muscle tissue is needed. In this study, we analyzed the concentrations of radioactive cesium in the blood and skeletal muscle of 88 cattle, and detected a linear correlation between them. We then developed software that can be used to estimate radioactive cesium concentrations in muscle tissue from blood samples. Distribution of this software to the livestock production field would allow us to easily identify high‐risk cattle, which would be beyond the safety regulation, before shipping out to the market. This software is planned to be released as freeware. This software would contribute to food safety, and aid the recovery of the livestock industry from the damage creacted by the 2011 Tohoku earthquake and tsunami.