Class III peroxidases (plant peroxidases) exist as large multigene families in higher plants, and most of them are localized in the cell wall. It has been reported that they are involved in lignification, cell elongation, stress defense, phytohormonal regulation, suberization and structural protein formation. However, the underlying mechanisms and the presentation of their functions are not fully understood. Plant peroxidases can function as catalytic enzymes that oxidize phenolic compounds while consuming hydrogen peroxide and/or as generators of reactive oxygen species. Moreover, biochemical approaches to characterize plant peroxidases have revealed the catalytic property of plant peroxidases responsible for lignin biosynthesis. In conclusion, not only spatiotemporal regulation of gene expression and protein distribution, but also differentiated oxidation properties of each plant peroxidase, define the function in the cell wall.

To clarify the static and dynamic properties of large-span wooden floors, we measured static deflection, bending stiffness, natural frequency and damping ratio of floors at four wooden schools and two wooden offices. The initial design deflection to span ratio was approximately 1/430 to 1/1100 for these floors. In addition, design deflections including creep to span ratio was approximately 1/280 to 1/800. These values were within the limitations defined by the Building Standards Law and the Standard for Structural Design of Timber Structures of the Architectural Institute of Japan, except for one elementary school. The experimental bending stiffness of beams or trusses was 1.1 to 3.9 times larger than the design value. On the other hand, the measured natural frequency of floors in actual wooden buildings ranged from 9.5 to 12 Hz. These values could be relatively accurately estimated using the theory of simply supported beams with applied dead loads. Additionally, the damping ratios ranged from 3.1 to 6.5%, almost the same as those in previous studies.

Manufacturers of wood flooring products pursue enhancement of a wood-like feeling of their products. However, to numerically evaluate the effect of various treatments to improve the wood-like feeling has been very difficult. This study aims to develop a novel evaluation technique which objectively describes appearances of wood floorings which contribute to a wood-like feeling by certain image characteristics. Forty-seven flooring products were collected. Their surfaces were illuminated at various lighting azimuths, and high-resolution images of the surfaces were captured. The surface images were subjected to multi-resolution contrast analysis and correlation analysis. Four image characteristics of “micro visibility”, “macro visibility”, “contrast anisotropy”, and “gloss shift” were derived from these image analyses, which corresponded well with the reflectance properties of the flooring products. Additional 20 flooring products were prepared for sensory evaluation by 24 ordinary consumers. Multiple regression analysis revealed that the image characteristics computed for the 20 flooring products explained the results of sensory evaluation well.

A calculation method based on the theory of a beam on an elastic foundation was presented to estimate the embedment stiffness and yield resistance of metal washers supported on timber. The practical applicability of the calculation method was verified by embedment tests of metal washers of various sizes.It was found that the calculated values of embedment stiffness and yield resistance of metal washers supported on timber agreed roughly with the experimental results. In addition, predicted deformation modes of metal washers supported on timber agreed with the modes observed in the experiments. However, estimation of effective beam width, which might be required to enable practical conversion of three-dimensional plate bending to two-dimensional beam bending, remained to be investigated.

We defined a knot assessment model based on the visual grading of Japanese Agricultural Standard (JAS) of lumber and attempted to optimize parameters of the model using simulated annealing. Parameters of the knot assessment model were optimized by maximizing coefficients of determination of regression models, using data of bending tests and surface images of 40 test pieces, 120 mm square cross section kiln-dried lumber with pith of Japanese larch (Larix kaempferi Lamb.). Values of the coefficient of determination of regression models using knot index values of optimized knot assessment models were much larger than those obtained by ordinary visual grading. However, knot index values of almost all test pieces were decided by a particular type of knot diameter ratio, suggesting overfitting. We then simplified the knot assessment model, eliminating the distinction between center or edge areas and types of single knot. Values of the coefficient of determination of regression models were then decreased compared to those of the above optimized knot assessment models. However, they were still larger than those based on ordinary visual grading, and there were significant differences between correlation coefficients of each single regression model.