Fire-resistant performance of a laminated veneer lumber joint with metal plate connectors protected with graphite phenolic sphere sheeting

Creep under fire of laminated veneer lumber (LVL) joined with metal connectors was studied. The fire-resistant performance of LVL butt joints connected with metal plates protected with graphite phenolic sphere (GPS) sheeting was discussed. The GPS sheeting was overlaid on the joint in different sizes and locations. The joint was exposed to a burner with a top flame temperature of 800°C and loaded with a load of 200 N to test for creep under fire. The results showed that the fire-resistant performance of the joint was markedly improved by the sheeting. The size and location of the GPS sheet significantly affected the time to rupture of the specimen, which was six times longer than that without GPS. Temperature measurements at the joint showed that the GPS sheeting distributed the heat along the surface and delayed failure. Thermographic images and analyses clarified the improvement in fire-resistant properties due to GPS.     

Plantlet regeneration from leaf protoplasts ofPopulus euphratica

Protoplasts were isolated from the leaves of sterile plants ofPopulus euphratica Oliv. by using 1% Cellulase “Onozuka” RS and 0.25% Pectolyase Y-23 in 0.6m of mannitol solution. Protoplasts were cultured in modified Murashige and Skoog's (MS) medium which contained no ammonium ions but was supplemented with BAP (6-benzylaminopurine), 2,4-D (2,4- dichlorophenoxy-acetic acid), and 1% sucrose at the cell density of 9×10⁴/ml. Cell divisions occurred in every culture medium, especially in the medium containing 0.5 mg/l of BAP and 0.1 mg/l of 2,4-D, in which callus was successfully induced by successive culture through cell cluster formation. Shoots were regenerated from the callus, and their growth was enhanced on 1/2 MS medium containing 0.8 mg/l of BAP. Finally, shoots were rooted and plantlets were regenerated on 1/2 MS medium without a hormone. A part of this paper was presented at the 106th Annual Meeting of the Jpn. For. Soc. (1995).     

Fire protection of a laminated veneer lumber joint by wood carbon phenolic spheres sheeting

Laminated veneer lumber joints made with metal plate connectors were protected with wood carbon phenolic spheres (CPS) sheeting and tested for creep under fire. The effects of the carbonizing temperature of charcoal, used as raw material for the CPS sheets, the thickness, and the location of the sheet on the joint regarding the fire-resistance performance of the joint were studied. The time to rupture of the joints covered with CPS sheets made from charcoal carbonized at 800°C (CPS800) was slightly prolonged compared with that of uncovered joints. On the other hand, the time to rupture of CPS sheets made from charcoal carbonized at 1600°C (CPS1600) was markedly extended. The changes in the charcoal properties due to increasing the carbonizing temperature might be the main reason the CPS1600 sheets had higher fire-resistance performance. The thickness and location of CPS1600 sheets have significant effects on the fire resistance of the joint. A highly fire-resistant laminated veneer lumber joint was obtained using a CPS1600 sheet. The CPS1600 sheet with a thickness of 3mm covering three sides of the joint prolonged the time to rupture 16-fold compared with that of unprotected joints.Part of this paper was presented at the 4th International Wood Science Symposium, Serpong, Indonesia, September 2002     

Genetic diversity of Populus euphratica populations in northwestern China determined by RAPD DNA analysis

Five Populus euphratica Oliver populations in northwestern China were analyzed using RAPD DNA markers to determine genetic diversity among and within populations. One hundred-and-five polymorphic bands were observed, ranging in size from 250 bp to 1700 bp, using 10 primers. Only one population on the north side of the Tianshern Range had a unique band common to all individuals that was not found in individuals from populations in the Tarim River valley. Intra-population genetic diversity was high in two populations along the Tarim River and low in the other three populations. There was no significant correlation between genetic distances and geographic distances. The result of correspondence analysis shows that the individuals from the three populations with low genetic diversity are isolated from each other. The result of cluster analysis based on genetic distance shows that the population in the Tianshern Range is genetically distant from the other populations. These results suggest that the Tianshern Range population was genetically isolated from the other populations.     

Estimation of rubberwood production in Cambodia

We estimated the production of rubberwood from 1996 to 2011 in Cambodia. We employed data from interview surveys with three rubberwood processing companies and statistics from estate rubber plantations and wood retailing companies. The result was that the end use of rubberwood in Cambodia was the sawntimber products, being exported to Vietnam and China. The yield rate from rubberwood stumpage into sawn timber was between 11.6 and 14.9%, closely matching the rates of Malaysia and Thailand. The average production of rubberwood roundwood from 1996 to 2011 was 254,697 m³/year, of which sawn timber as well as residuals in secondary processing was 84,559 and 170,138 m³/year, respectively. Although the timber production of Cambodia has declined sharply due to the strict restriction of natural forest logging, rubberwood could explain more than 60% of the domestic industrial roundwood production from 2000. We suggest the necessity of monitoring the expansion of rubber plantations in new rubber producing countries and linking the rubberwood production with the regional wood resource management.     

The relation between pathogenicity and plaque size of Getah virus Kanagawa strain in suckling mice

The relation among biological properties, particularly pathogenicity for suckling mice, and plaque size was studied in four virus strains: Getah virus strain Kanagawa; two strains obtained by plaque cloning of the Kanagawa strain, Getah Kanagawa SP (G-K-SP) strain which forms small plaques (SP) only and strain G-K-LP which forms large plaques (LP) only; and strain Haruna which forms SP only. There were no marked differences among the four strains in serological properties, growth curves and sensitivity to pH, trypsin and temperature. Strain G-K-LP showed higher pathogenicity for suckling mice than strain G-K-SP. However, the pathogenicity of strain Haruna, which forms SP only, was as high as that of strain G-K-LP. Some of the clones in SP of strain Kanagawa kill all mice in 5 to 6 days after inoculation while the others required 9 to 11 days or longer before causing death. The present study showed that the pathogenicity of Getah viruses shortly after being isolated from the field, such as the Kanagawa strain, is different between large and small plaques, and even among small plaques, at least in suckling mice, and that the pathogenicity has no relation to plaque size.     

Root-growth response of winter barley to subsoiling

Root growth of winter barley was studied on 2 Belgian silt loam soils after subsoiling to 60 cm depth. In the first field (well-drained) rooting depth increased significantly after removal of a plough pan. At the flowering stage, total root weight in the soil layers between 25–50 cm and 50–75 cm was 125% and 325%, respectively, higher on the subsoiled plots than on the control. The P₂O₅ and K₂O concentrations in the roots were significantly increased by 20% and 40%, respectively. In the second field (imperfectly drained) with initially relatively high bulk densities in the subsoil, the influence of subsoiling was negligible. In this study, the clearly-shown root-growth retardation that resulted in a lower yield on the control, seemed to be caused by the high penetration resistance in the plough sole (> 3MPA) rather than poor aeration status induced by the high bulk densities.