Dynamic properties of three types of wood-based composites

This study used a vibration test method to show that grain angles of face veneer have substantial effects on sound velocities and dynamic Youngs moduli of three types of wood-based composites. The sound velocity at 0° grain angle of face veneer was the highest, and it decreased with increasing grain angle in the range of 0° to 90°. This tendency was similar to that for dynamic Youngs modulus. The relationship between the grain angle of face veneer and the sound velocity of three types of wood-based composites can be expressed in the form of Hankinsons equation or a second-order parabolic equation. This study also showed that the application of orthotropic elasticity theory was valid for the three types of wood-based composites. The relationship between the grain angle of the face veneer and the Youngs modulus of three types of wood-based composites can be expressed in the form of the Jenkin equation, Hankinsons equation, or a second-order parabolic equation. Rule of mixture can also be used to predict the Youngs modulus of wood-based composite from the Youngs moduli of the two elements.Part of this study was presented at the 53rd Annual Meeting of the Japan Wood Research Society, Fukuoka, Japan, March 2003 and the 15th Annual Meeting of Chugoku Shikoku Branch of the Japan Wood Research Society, Higashi-Hiroshima, Japan, September 2003     

Antioxidative activity of tree phenolic constituents 1: Radical-capturing reaction of flavon-3-ols with radical initiator

The present work was undertaken from the standpoint of radical-capturing ability with regard to the antioxidative ability of flavonoids, especially flavonols distributed widely in woody plants. In regard to the flavonols, six methyl derivatives were initially prepared from quercetin and its litinoside. Their radical-capturing constants were determined strictly by the stopped-flow spectroscopic method. It was proved that the radical-capturing ability of quercetin mainly involves the vicinal C₃. and C₄, hydroxyl groups and the C₃ hydroxyl group. To clarify the reaction mechanism begun at the C₃ hydroxyl group of quercetin, 5,7,3,4-tetramethylquercetin (TMQ), flavon-3-ol (F30) and so on were treated with 2,2-azo-bis-(2,4-dimethylvaleronitrile) (AMVN). Six products (1–6) containing one depside and its two hydrolytic products, two valeronitrile adducts, and others were isolated from the reaction mixture of TMQ and their structures determined by instrumental analyses. Similarly, F30 gave four products, 7–10, which corresponded to the above products 1–3 and 5 (one depside, its two hydrolytic products, and one adduct), respectively. 3,5,7,3,4-Pentamethylquercetin (PMQ) and flavon-3-O-methylate (F3M) gave no products. The quantitative change of the products with reaction time was determined spectroscopically. An initial reaction pathway for the radical-capturing reaction of flavon-3-ols with AMVN was proposed based on the products and their amounts. The main route — formation of depside and its hydrolytic products via ketohydroperoxide (3) or ketohydroperoxy radical (4) - was similar to that of the oxidation reaction of quercetin with quercetinase and light.Part of this paper was presented at the 46th and 47th annual meetings of the Japan Wood Research Society, Kumamoto and Kouchi, April 1996 and 1997     

Changes of chemical composition and crystalline of compressed Chinese fir wood in heating fixation

The changes in relative crystalline, chemical composition and internal structure of compressed Chinese fir wood after different heating fixations were found strictly related to fixation conditions. The compressed wood powders were fixed either by heating at different temperatures all resulting in a 10% recovery, or by incubating at 180℃ for different periods with subsequent recovery levels. Both X-ray diffraction and infrared absorption of those samples have been measured. Relative crystalline increases at early stage of heating fixation, and then decreased gradually. Hemicellulose and lignin decomposition were induced by the fixation process, especially at 180℃, and lignin was degraded actively. Furthermore, absorbed water was lost after heating, but cellulose did not change markedly. Although different fixation pathways can result in the same recovery level, the major chemical reactions underlying them vary, which is consistent with the difference of fixation mechanisms.     

Killing of feline T-lymphocytes by gamma-rays and energetic carbon ions

High linear energy transfer (LET) heavy charged particles have previously been applied clinically to human cancer radiotherapy because of their excellent physical properties of selective dose distribution and higher relative biological effectiveness (RBE) for human; however, such an approach has yet to be applied to cat patients. The present study investigates the biological effectiveness of low-LET gamma-rays (0.2 keV/micro m) compared to high-LET carbon ions (114 keV/micro m) in feline T- lymphocyte FeT-J cells. Clonogenic survival analysis revealed that the RBE value of carbon ions was 2.98 relative to a 10% survival dose (D(10)) by gamma-rays, and that the inactivation cross-section in cells exposed to gamma-rays and carbon ions was 0.023 and 38.9 micro m(2), respectively. Terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) analysis revealed that TUNEL-positive frequency in carbon-irradiation cells is higher than for gamma-irradiated cells against exposure to the same physical doses, but that very little difference in TUNEL-positive frequency is observed between cells exposed to the respective D(10) dose of gamma-rays. Our data thus indicate that carbon ions are more effective for cell killing than gamma-rays at the same physical doses, but kill cells to an extent that is comparable to gamma-rays at the same biological doses. Carbon ion radiotherapy is therefore a promising modality for cat patients.     

Factors determining the distribution of a keystone understory taxon, dwarf bamboo of the section Crassinodi, on a national scale: application to impact assessment of climate change in Japan

The objective of this study was to identify climatic factors determining the distribution of a keystone understory taxon, section Crassinodi of the genus Sasa, and assess the impacts of climate change on the taxon. Relationships between the distribution of sect. Crassinodi and five climatic variables were explored using classification tree analysis. Potential habitats under current climate and future climate in 2081–2100 were predicted. Potential habitats were further divided into suitable and marginal habitats. The predictive accuracy of the model was assessed using receiver operating characteristic analysis and by comparing model predictions with an independent dataset. The model was reasonably accurate. It showed that the warmth index (WI) and snow cover were the most important climatic variables for Crassinodi distribution. Potential habitats were limited to cooler regions with WI <102.7°C month. Suitable habitats were limited to even cooler regions with WI <84.8°C month. The model also showed that areas with deeper snow than previously reported would provide suitable habitats for Crassinodi under some climatic conditions. In 2081–2100, 37.4% of current potential habitats are predicted to become non-habitats because of increases in WI. Most currently suitable habitats are predicted to vanish from western Japan by 2081–2100. Meanwhile, Hokkaido and high-elevation areas of eastern Honshu will sustain suitable habitats. Sect. Crassinodi, which is adapted to less snowy climates, is predicted to be more affected by climate change than sect. Sasa and Macrochlamys, which are adapted to snowy climates.     

Examination of the failure behavior of wood with a short crack in the radial–longitudinal system by single-edge-notched bending test

The failure behavior of wood with a short crack was examined by conducting the single-edge-notched bending tests of a radial-longitudinal system on Agathis specimens. In the test, the mode I critical stress intensity factor was measured, and its validity was checked by the result from double cantilever beam testing method. The mode I critical stress intensity factor decreased when the crack length approached zero. With crack length correction, a constant critical stress intensity factor was obtained over a wide range of crack length including crack-free specimen.     

Lectin binding pattern of gastric mucosa of pacific white-sided dolphin, Lagenorhynchus obliquidens

The stomach of the Pacific white-sided dolphin is divided into three parts: forestomach, proper gastric gland portion, and pyloric chamber. The histological features of the dolphin stomach are similar to those of terrestrial mammal stomachs, although the distribution of glycoconjugates in mucosal cells of the dolphin stomach is unknown. To learn about glycoconjugates in cetacean gastric mucosa, the glycoconjugate distribution in the mucous epithelium of the Pacific white-sided dolphin was studied using 21 lectins. Among the lectins tested, GSL-I and DBA specifically labelled the superficial layer of the forestomach epithelium. GSL-I, SBA, RCA-I, VVA, GSL-II, DSL, LEL, STL, s-WGA, WGA, PNA, and Jacalin labelled the luminal surface of the chief cells in the proper gastric gland. GSL-I, SBA, RCA-I, DSL, LEL, STL, s-WGA, PNA, and LCA labelled tubular structures in the cytoplasm of parietal cells. The surface portion of the pits in the pyloric chamber strongly reacted with RCA-I, GSL-II, WGA, PNA, LCA, PHA-L, and UEA-I, whereas the neck portion reacted weakly. Although lining one tubular portion, individual secretory cells in the pyloric gland displayed a heterogeneous reaction. This is the first report on the lectin histochemistry of a cetacean stomach and reveals GSL-I and DBA as specific marker lectins for the cornified stratified squamous epithelium cells of the Pacific white-sided dolphin. The stomachs of cetaceans and terrestrial mammals have similar histological features and mucous glycoconjugate content.