| 1. |
Ahmad, M. H., Amini, M. H. M., Sobri, S. A., Sakagami, H., Hermawan, A., Effect of radial growth rate on wood properties variation of Sentang (Azadirachta excelsa) tree planted in Kelantan, Malaysia, BioResources, 10.15376/biores.18.3.5013-5027, 18, 3, 5013-5027, 2023.06, Properties of Sentang wood planted in Kelantan, Malaysia, were studied, focusing on the effect of radial growth rate on variation in the fiber and vessel element dimensions, moisture content, density, shrinkage, bending, and compression strength at the breast height of the tree. The trees were categorized into slow-, average-, and fast-growth categories, based on their breast height diameter and standard deviation. The variations in properties were then examined from the pith to the bark. The fiber length and diameter tend to decrease until a certain distance from the pith, followed by an increase toward the bark. Contrastingly, the vessel element length and diameter tend to increase until a maximum size is reached and then exhibit a relatively constant size toward the bark. The fast-growing trees tended to have longer and larger fibers, while the slow-growing trees tended to have longer and larger vessel elements. In addition, the fast-growing trees tended to have a higher green moisture content and shrinkage, lower density, lower modulus of rupture (MOR), and lower compression strength. The results revealed that growth rate seems to influence the modulus of elasticity (MOE) less than the MOR and compression strength.. |
| 2. |
Adutwum, J. O., Sakagami, H., Koga, S., Matsumura, J. , Space-time analysis of the longitudinal variation in wood specific gravity of teak and its effect on tree growth and development, BioResources, DOI: 10.15376/biores.18.2.2657-2669, 18, 2, 2657-2669, 2023.02, The space-time structure of a teak wood specific gravity (SG) dataset was analyzed using a mixed-effects model. Spatial correlation increased in space, a phenomenon attributable to the maturation of apical meristems, while the temporal correlation of vascular meristems decreased over time. The decay of temporal correlation over time was attributed to the diminishing crown effect on the later formed wood further away from the pith, morphogen gradient, and probably changing microenvironmental conditions. The Kronecker product was used to collect spatiotemporal data on the intricate dynamic process of the evolution of the apical and lateral meristems. The results showed that height and relative radial distance (RRD) (i.e., the flow of time with wood formation) were statistically significant factors, with their interaction showing no significance. The results confirm the usefulness of using the space-time approach to elucidate the interaction between the apical and lateral meristems, two major inherent biological systems that control tree growth and wood formation dynamics. To understand the origins of patterns that vary both temporally and spatially in the tree, future work should describe the variation of SG within the tree due to increasing height (space) and diameter (age) as a matrix; then the correlation function can be modelled.. |
| 3. |
Jerry Oppong Adutwum, Hiroki Sakagami, Shinya Koga, Junji Matsumura, An application of mixed-effects model to evaluate the role of age and size on radial variation in wood specific gravity in teak (Tectona grandis), Journal of Wood Science, doi.org/10.1186/s10086-023-02076-3, 69, 9, 2023.02, To test whether radial variation of wood specific gravity (WSG) is controlled by tree age or tree size in teak (Tectona grandis L.f ) plantation trees, opposing different-length pith-to-bark strips which represents the differential lateral growth rate was compared using mixed-effects model which considers the heterogeneity of variances and depend- ency in the data to gain insight into the stochastic processes that govern the wood formation process. Various models were tested in devising an appropriate radial WSG model. Models that accounted for serial correlation in WSG data performed better than the simple structure that assumes zero correlation between measurements. The autoregressive plus random tree effect structure performed better in describing the radial variation pattern. The variability of the data related to random fluctuations during tree development and the wood formation process is modeled by the autore- gressive parameter revealing the intrinsic complexity of wood formation. Since they cannot be attributed to observed factors, models should consider temporal or serial correlations when assessing wood quality. The results revealed that tree age is a decisive factor in controlling the WSG of wood, while tree size is statistically less important. Further- more, the core wood production period varies with the growth rate. It is shown that the core wood area decreased with slow growth. Findings presented here appear to provide the first demonstration of radial variation in WSG with respect to growth rate and age for planted teak growing in Ghana.. |
| 4. |
Rongfeng Huang, Noboru Fujimoto, Hiroki Sakagami, Shanghuan Feng , Sandwich compression of sugi (Cryptomeria japonica) and hinoki (Chamaecyparis obtusa) wood: density distribution, surface hardness and their controllability, Journal of Wood Science, https://doi.org/10.1186/s10086-021-01970-y, 67, 2021.06. |
| 5. |
Andi Hermawan, Hiroki Sakagami, Noboru Fujimoto, Creep behaviour of Japanese cypress timber under various hygrothermal conditions, Wood Material Science & Engineering, doi.org/10.1080/17480272.2021.1939420, 2021.06. |
| 6. |
Tekat Dwi Cahyono, Wahyu Dwianto, Wayan Darmawan, Hiroki Sakagami, Change in the surface roughness and surface free energy of Samama (Anthocephalus macrophyllus) after citric acid impregnation through pre-compression method, Journal of Adhesion Science and Technology , https://doi.org/10.1080/01694243.2021.1934280, 2021.06. |
| 7. |
Chikara Mizoguchi, Hiroki Sakagami, Noboru Fujimoto, Tetsuya Nakao, Effect of Growth Ring Angle on Lateral Enlargement of Compressed Cryptomeria japonica Wood Impregnated with Polyethylene Glycol, Bioresources, 10.15376/biores.15.4.8756-8769, 15, 4, 8756-8769, 2020.10. |
| 8. |
Andi Hermawan, Hiroki Sakagami, Sharizal Ahmad Sobri, Mohd Hazim Mohamad Amini, Sitti Fatimah Mhd. Ramle, Shaharlina Rasid, The effects of drying temperatures on preservative retention and penetration of some Malaysian fast-growing species timbers, Drying technology, 10.1080/07373937.2020.1806866, 2020.08. |
| 9. |
Hiroki Sakagami, Microcrack propagation in transverse surface from heartwood to sapwood during drying, Journal of Wood Science, 10.1186/s10086-019-1812-6, 65, 33, 2019.07. |
| 10. |
Hiroki Sakagami, Saki Higurashi, Tetsuya Tsuda, Satoshi Seino, Susumu Kuwabata, Decay resistance of Polymerized ionic liquid modified woods, Bioresources, 13, 3, 5702-5710, 2018.06. |
| 11. |
Hiroki Sakagami, Atsuro Tokunaga, Noboru Fujimoto, Shinya Koga, Isao Kobayashi, Ikuo Momohara, Effects of drying temperature for Cryptomeria japonica on the permeability of wood preservative. II. The permeability of dried, split log pieces, Bioresources, 10.15376/biores.11.3.6896-6908, 11, 3, 6896-6908, 2016.07, 異なる温度で木材を乾燥すると薬液の注入性が異なる。. |
| 12. |
Kijidani Yoshio, Shinya Koga, Sakgami Hiroki, Matsunaga Hiroshi, Effects of application of trans-zeatin on tracheid differentiation in mature sugi (Cryptomeria japonica) trees, Journal of wood science, 10.1007_s10086-016-1559-2, 2016.05. |
| 13. |
Sakgami Hiroki, Atsuro Tokunaga, Noboru Fujimoto, Shinya Koga, Isao Kobayashi, Ikuo Momohara, Effects of drying temperature for Cryptomeria japonica on the permeability of wood preservative. I: The permeability of dried logs, Bioresources, 11, 2, 4781-4793, 2016.04. |
| 14. |
Kijidani yoshio, Kawasaki yoshinobu, Matsuda daisuke, Nakazono Fumiaki, Hayakawa Masato, Mutaguchi Hisashi, Sakgami hiroki, Tree heights in the ring-formed years affect microfibril angles in the rings from juvenile to mature wood at breast height in hinoki trees (Chamaecyparis obtusa), Journal of Wood Science, 10.1007/s10086-014-1426-y, 60, 6, 2014.12. |
| 15. |
Hiroki Sakagami,Fumiko Hatae, Hiroyuki Yamamoto, Yoshio Kijidani, Junji Matsumura, Microcrack Propagation in Red and Black Heartwoods of Cryptomeria japonica During Drying, Bioresource, 8, 4, 5983-5994, 2013.10. |
| 16. |
Hiroyuki Yamamoto, Hiroki Sakagami, Yoshio Kijidani, Junji Matsumura, Dependence of Microcrack Behavior in Wood on Moisture Content during Drying, Advances in Materials Science and Engineering, 2013, 802639, 2013.09. |
| 17. |
Andy Hermawan, Ryo Nakahara, Noboru Fujimoto, Hiroki Sakagami, Performance of Sugi lamina impregnated with low-molecular weight phenolic resin, Journal of wood science, 59, 4, 299-306, 2013.08. |
| 18. |
Felix Dalitso Kamala, Hiroki Sakagami, Kazuyuki Oda, Junji Matsumura, Wood density and growth ring structure of Pinus patula planted in Malawi, Africa., IAWA Journal, 34, 1, 61-70, 2013.05. |
| 19. |
Hermawan, Andi, Noboru Fujimoto, Hiroki Sakagami, A Study of Vacuum-Drying Characteristics of Sugi Boxed-Heart Timber, Drying technology, 31, 5, 587-594, 2013.03. |
| 20. |
Tsuda,T.,Nemoto,N., Mochizuki,E., Kishida, S., Hayakawa, E. Ishigaki, Y., Sakagami, H., Arakaki, A., Matsunaga, T., Kuwabata, S., Development of ionic liquid suitable for electron microscope technique, 医学生物学電子顕微鏡技術学会誌, 26, 2, 58-60, 2012.04. |
| 21. |
Tsuda Tetsuya, Mochizuki Eiko, Kishida Shoko, Sakagami Hiroki, Tachibana Shigeaki, Ebisawa Masaharu, Nemoto Noriko, Nishimura Yoshitomo, Kuwabata Susumu, Observation of Electrochemical Reaction and Biological Specimen by Novel Analytical Technique Combined with Room-Temperature Ionic Liquid and Scanning Electron Microscope, ELECTROCHEMISTRY, 80, 5, 308-311, 2012.05. |
| 22. |
Hiroki Sakagami, Junji Matsumura, Kazuyuki Oda, In situ visualization of microcracks by a confocal laser scanning microscopy system , Wood Material Science and Engineering, 5, 2, 110 - 115, 2010.05. |
| 23. |
Hiroki Sakagami, Junji Matsumura and Kazuyuki Oda, In-situ visualization of hardwood microcracks occurring during drying, Journal of Wood Science, 55, 5, 323-328, 2009.10. |
| 24. |
Hiroki Sakagami, Kosuke Tsuda, Junji Matsumura and Kazuyuki Oda, Microcracks occurring during drying visualized by confocal laser scanning microscopy, IAWA Journal, 30, 2, 179-187, 2009.03. |
| 25. |
Hiroki Sakagami, Junji Matsumura and Kazuyuki Oda, Shrinkage of tracheid cells with desorption visualized by confocal laser scanning microscopy, IAWA Journal, 28, 1, 29-37, 2007.01. |
