Three-Dimensional Exploration of Soft-Rot Decayed Conifer and Angiosperm Wood by X-Ray Micro-Computed Tomography

Water concentration and rate of decrease in shiitake cultivation log during fruiting body development, as measured by MRI

Large shiitake mushrooms (Lentinula edodes, pileus > 8 cm in diameter) are difficult to cultivate and account for only 3-5% of the total harvest. This study focused on the water absorption process within a log during the growth of fruiting bodies in order to increase the yield of large shiitake mushrooms. Konara oak logs (Quercus serrata, 85-95 mm in diameter, 290 mm in length) were inoculated with shiitake mycelium plugs and nine months later, young fruiting bodies developed, at which point the log was analyzed using magnetic resonance imaging (MRI) over a period of two weeks. The signal intensity and T1 and T2 relaxation time constants were determined from the acquired images, along with the distribution of water concentration within the entire log. The axial distributions of water concentrations in the log were higher in the 80 mm region around the fruiting body. The rate of decrease in water concentration indicated that water was supplied to the fruiting body from 80 mm axially in the upper half of the sapwood in the log. On the other hand, the water concentration in the heartwood did not decrease and the heartwood did not contribute to the water supply to the fruiting bodies.

Study on the Fracture Toughness of Softwood and Hardwood Estimated by Boundary Effect Model

The tensile strength and fracture toughness of softwood and hardwood are measured by the Boundary Effect Model (BEM). The experimental results of single-edge notched three-point bending tests indicate that the BEM is an appropriate method to estimate the fracture toughness of the present fibrous and porous woods. In softwood with alternating earlywood and latewood layers, the variation in the volume percentage of different layers in a small range has no obvious influence on the mechanical properties of the materials. In contrast, the hardwood presents much higher tensile strength and fracture toughness simultaneously due to its complicated structure with crossed arrangement of the fibers and rays and big vessels diffused in the fibers. The present research findings are expected to provide a fundamental insight into the design of high-performance bionic materials with a highly fibrous and porous structure.