The genetic variation of the age of transition from juvenile to mature wood, based on tracheid length, in hybrid larch (Larix gmelinii var. japonica × L. kaempferi) F₁, and the influence of growth rate on its trait, were studied. Wood samples were collected from 100 29-year-old trees belonging to 19 full-sib families and tracheid length was determined for four-ring segments from rings 2 to 22. Tracheid length was plotted against age to determine the age of transition from juvenile to mature wood. The mean value of transition age was 18.8 years, ranging from 11.5 to 25.4. The narrow-sense heritability estimate for transition age was 0.24 and, assuming selection of the top 25% and 10% of the families, the predicted gain for single trait direct selection was 0.8 and 1.1 years, respectively. Neither genetic nor phenotypic correlations were found between transition age and growth rate. The tracheid length was not correlated with growth rate or transition age. These results suggest that promoting growth rate through forest tree management and breeding should affect neither the age of transition from juvenile to mature wood nor tracheid length. The age of transition is under moderate genetic control, but response to selection for its trait would take approximately one year.

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The effects of treatment with NaOH aqueous solution on the shape of Yezo spruce (Picea jezoensis Carr.) and its mechanism were examined by comparison with results for ramie fibers. Wood samples contracted in the longitudinal direction and twisted upon treatment with NaOH aqueous solution, which took place when wet. This shape change by the treatment was similar to that of ramie fibers. The ratio of length to width of wood samples and the length of ramie fibers decreased with increasing concentration of NaOH aqueous solution above 10%. These decreases did not arise during the drying process but during the treating process with the NaOH aqueous solution. The mechanism of the change in shape was explained on the basis of Stöckmann's model where the contraction and twist of wood samples are caused by forces in both the longitudinal and tangential directions which are components of the contractive forces in the cellulose microfibrils of the cell wall.

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The torsional fatigue properties of two woods (Japanese beech and white cedar) under controlled torque were investigated experimentally. Pulsating torsional loading was applied about the longitudinal direction of wood. The pattern of repetitive loading was the reversed cyclic sine-waveform loading and the applied frequencies were 0.1 Hz and 1 Hz. The following results were obtained. 1) A negative correlation was observed between the shear stress level and the logarithm of the number of cycles to failure (N_f). 2) The N_f at the frequency of 1 Hz was larger than that at 0.1 Hz. 3) The average energy loss per unit cycle was inclined to converge to a certain value with increasing N_f. This value was considered to be equal to a quantity which was not related to the initiation and propagation of micro-fractures in the specimen. We estimated the converged values at 0.7 kJ/m³ for Japanese beech and 0.5 kJ/m³ for white cedar. From these results, the torsional fatigue limits of both species were assumed to be about 30% of stress levels.

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Sugi (Cryptomeria japonica D. Don) and balsa (Ochroma lagopus Sw) specimens in the air-dried condition were compressed using a roller press. We measured the frequency and degree of defects and fractures in the specimens caused by the compression.
The cell wall was sequentially compressed due to shear deformation. The specimens were densified in thickness and slightly elongated in width. As a result, alligatoring cracks, longitudinal splits, surface cracks, cup, crook and shear cracks occurred after roller pressing under extreme conditions. Both the frequency and the degree of alligatoring cracks, longitudinal splits and surface cracks increased in proportion to the thickness or the degree of compression of the specimen, or in inverse proportion to the size of the roller diameter. Moreover, the frequencies of the alligatoring cracks and the surface cracks had a positive relation to the contact angle, which was calculated from thickness, degree of compression and roller diameter. The macroscopic defects of sugi and balsa specimens tended to increase at, respectively, 8 and 12 or more degrees of contact angle.

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Lateral resistance of single-anchor-bolt joints was examined experimentally for ordinary specifications of Japanese post and beam constructions. Tested bolts were 12 or 16 mm in diameter and lead-hole clearances were 0, 3, and 6 mm. The specimens with 12 mm bolts were loaded parallel and perpendicular to the grain, and the specimens with 16 mm bolts were loaded only parallel to the grain.
The principal test results were as follows. (1) Anchor-bolt joints loaded perpendicular to the grain had much lower maximum resistance, much smaller maximum slips and much lower energy capacities. (2) Maximum lateral resistance and maximum slips of the anchor-bolt joints with 16 mm bolts varied over a wide range. (3) The energy absorption capacities of the anchor-bolt joints with 16 mm bolts closely resembled those of the joints with 12 mm bolts in spite of their larger maximum lateral resistance and initial stiffness. (4) Safety factors calculated from the fifth percentile lower limit maximum resistance and the short term allowable resistance were larger for the joints with 12 mm bolts than for the joints with 16 mm bolts.

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Wire-marks of 13 different boxed facial tissue papers, from 3 manufacturers, with 5 different brand names, sold in 3 areas in Japan, were examined using a fast Fourier transform (FFT) image analysis for forensic comparisons. Each sheet of 2-ply tissue of all of the boxes was scanned to obtain its reflected image using a commercially available flatbed scanner with black Kent paper on its back.
Every sheet in each box, and each sheet of 160 through 200 pairs of 2-ply tissue was examined. Each sheet of 2-ply tissue had a similar power spectrum in all cases. Considerations of manufacturing processes, however, imply both sheets are from different rolls of paper, i.e., scientific criminal investigations would require examination of both sheets.
Tissues of 13 brand names were sorted into 10 types of power spectra. Some boxes contain one type of power spectrum only but other boxes may contain up to 4 different types.
Some facial tissue of the same brand name obtained in different areas showed similar power spectra while some different brand names also showed similar power spectra.
Wire-marks seen in boxed facial tissue paper can be a clue for forensic purposes but will not be a determining factor.

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At present, moment-resisting connections for glulam constructions are widely constituted as drift-pin joints with insert-steel gusset plates, as well as bolted joints. These joints consume much steel and require complex design calculations. Therefore, Lagscrewbolts^® were developed as a simple and economical timber connector. Lagscrewbolts have a lagscrew type thread on the outside surface and are threaded like a nut on the inside at one end of the shank.
In this study, a series of tests were conducted to clarify the effects of lead hole diameter, embedment depth, embedment direction and edge distance on the pull-out resistance of Lagscrewbolts. Lagscrewbolts having 30 mm top thread diameter and 25 mm root diameter were used. For timber members, Douglas-far glulam of E105-F300 grade were used.
The results obtained were as follows :
1) The optimum lead hole diameter was 27 mm.
2) Maximum pull-out load (P_max) vs. embedment depths, and slip modulus (K_s) vs. embedment depths showed positive correlations. These relationships were almost linear.
3) The maximum pull-out load (P_max) parallel to the grain was 0.75 times of that for perpendicular to the grain, and the pull-out slip modulus (K_s) parallel to the grain was 3 to 6 times of that for perpendicular to the grain.
4) The suitable edge-distance was thought to be more than 1.5d (d is the thread top diameter of the Lagscrewbolt).

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Wrong:coverting
Right:converting

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