Estimation of shear strength of dowel-type timber connections with multiple slotted-in steel plates by European yield theory

The shear strength of dowel-type timber connections with multiple slotted-in steel plates was estimated based on European yield theory. The values calculated based on the yield theory were compared with experimentally obtained results. An experiment was performed on dowel-type timber connections with two and three slottedin steel plates under lateral loads parallel to the grain. The yield mode of the dowel-type connection assumed in this study corresponds approximately to the failure mode of the connection obtained from the experiment. The shear strength of the dowel-type connections calculated based on the yield theory showed good agreement with the results for shear strength obtained in the experiment. The yield theory was useful for estimating the shear strength of the doweltype connection with multiple slotted-in steel plates. The shear strength of the dowel-type connection was greatly affected by the spacing of the steel plates, the number of steel plates, and the timber thickness. The values of these parameters that showed the proper shear strength of the dowel-type connection could be estimated based on the yield theory. Part of this paper was presented at the 9th Timber Engineering Forum of the Japan Timber Engineering Society, December 2005     

Determination of embedding strength of wood for dowel-type fasteners

Embedding tests parallel and perpendicular to the grain were conducted to produce a database of embedding strength of wood for the design of dowel-type joints. Dowel diameters were 8,12,16, and 20mm. Embedding strength was evaluated by the 5% off-set method and a maximum load up to 5mm displacement according to EN383. The embedding strength parallel to the grain evaluated by the former method showed values close to those obtained with the latter method, but they showed a significant difference in tests conducted perpendicular to the grain. The embedding strength parallel to the grain was 0.9 times as large as the compressive strength parallel to the grain regardless of the evaluation method. The embedding strength perpendicular to the grain evaluated by the 5% off-set method was four times as large as the compressive strength perpendicular to the grain. When the embedding strength perpendicular to the grain was evaluated by a maximum load up to 5mm displacement according to EN383, the ratio of embedding strength perpendicular to the grain to the compressive strength perpendicular to the grain decreased as the dowel diameter increased.Part of this paper was presented at the annual meeting of the Architectural Institute of Japan 1999, Hiroshima, September 1999; the 50^th annual meeting of the Japan Wood Research Society, Kyoto, April 2000; and the World Conference on Timber Engineering 2000, Whistler, Canada, July–August, 2000     

Estimation of yield and ultimate strengths of bolted timber joints by nonlinear analysis and yield theory

A finite element nonlinear analysis was conducted on bolted timber joints under lateral loads parallel and perpendicular to the grain. The results obtained from this analysis were compared with the experimental results and calculated values based on the yield theory. The analysis and experiment were performed on double shear bolted joints parallel and perpendicular to the grain with steel side plates and a slotted-in steel plate. It was found from the analysis that the yielding of wood and bolt occurred before the overall yielding of the bolted joint. Shear strength of bolted joints calculated from the yield theory using the embedding yield strength of wood and the yield moment of the bolt showed comparatively good agreement with the shear strength evaluated by 5% offset of the load–slip curve in the experiment and analysis. The shear strength of the bolted joint calculated from the yield theory using the embedding ultimate strength of wood and the ultimate moment of the bolt agreed quite well with the shear strength evaluated by the maximum load up to 15mm slip in the analysis. The former, parallel and perpendicular to the grain, were 11% and 34%, on average smaller than the latter in the experiment.Part of this paper was presented at the 52nd Annual Meeting of the Japan Wood Research Society, Gifu, April 2002; the Annual Meeting of Architectural Institute of Japan 2002, Ishikawa, August 2002; and the World Conference on Timber Engineering 2002, Shah Alam, Malaysia, August 2002     

Digestive,fermentative, and physical properties of pineapple residue as a feed for cattle

The intake, digestion, and ruminal fermentation properties; the antioxidative activity; and the physical effectiveness of pineapple residue (PR) from the cut-fruit industry as a feed for cattle were investigated. Four nonlactating Holstein cows were fed a basal diet and diets with 1.4- and 3.6-kg dry matter (DM)/day of PR (low-PR and high-PR diets, respectively). The DM digestibility and total digestible nutrients were 71% and 70%, respectively. Ruminal pH, volatile fatty acids, and ammonia-N did not differ among the diets. The numbers of total viable, amylolytic, cellulolytic, and methanogenic bacteria and protozoa, and microbial protein synthesis in the rumen also did not differ significantly. Blood triglyceride, nonesterified fatty acids, urea nitrogen, and aspartate transaminase were lower in the high-PR diet. Feeding PR did not affect blood malondialdehyde, although PR has a higher antioxidative value than other commonly used feeds. The particle distribution of PR satisfied the recommended range for haylage. The chewing time for ingestion and rumination did not change with PR content, and the roughage value index of PR was 57-min/kg DM. These results suggest that PR has good intake and digestion properties and satisfactory physical effectiveness. Even a high-PR-content feed unlikely induces the risk of ruminal acidosis.     

Seroepidemiological survey of morbillivirus infection in Kuril harbor seals (Phoca vitulina stejnegeri) of Hokkaido, Japan

Serological analysis was performed to detect morbillivirus infection in Kuril harbor seals in Hokkaido, Japan. Serum samples were collected from the seals at Nosappu (231 sera), Akkeshi (16), and Erimo (75) between 1998 and 2005. Antibodies to phocine distemper virus (PDV) were detected by ELISA in seals from Nosappu and Erimo. Antibodies to PDV were found in 56% (5/9) of the sampled seals from Nosappu in 1998, versus only 5% (3/66) for 2003, 1% (1/79) for 2004, and 1% (1/77) for 2005. These suggest epidemic caused by the virus in or before 1998. As antibody-positive seals included juvenile seals in 2003 and 2005, sporadic infections of the virus are thought to have occurred in recent years. In Erimo, antibodies to PDV were found in 50% (14/28) of sampled seals in 2004, versus only 13% (1/8) for 1999, 7% (1/15) for 2003, and 0% (0/24) for 2005. These suggest sporadic infection by the virus before 2003 and the epizootic between after autumn in 2003, when samples of 2003 were collected, and 2004. Since antibodies to canine distemper virus (CDV) were detected in one adult seal from Nosappu in each year from 2003 to 2005, sporadic infections of the virus were suggested. There were no difference in incidence of seals with antibodies to the viruses between males and females and between juveniles and adults.     

Isolation of a novel mutant gene for soil-surface rooting in rice (Oryza sativa L.)

Background

Root system architecture is an important trait affecting the uptake of nutrients and water by crops. Shallower root systems preferentially take up nutrients from the topsoil and help avoid unfavorable environments in deeper soil layers. We have found a soil-surface rooting mutant from an M₂ population that was regenerated from seed calli of a japonica rice cultivar, Nipponbare. In this study, we examined the genetic and physiological characteristics of this mutant.

Results

The primary roots of the mutant showed no gravitropic response from the seedling stage on, whereas the gravitropic response of the shoots was normal. Segregation analyses by using an F₂ population derived from a cross between the soil-surface rooting mutant and wild-type Nipponbare indicated that the trait was controlled by a single recessive gene, designated as sor1. Fine mapping by using an F₂ population derived from a cross between the mutant and an indica rice cultivar, Kasalath, revealed that sor1 was located within a 136-kb region between the simple sequence repeat markers RM16254 and 2935-6 on the terminal region of the short arm of chromosome 4, where 13 putative open reading frames (ORFs) were found. We sequenced these ORFs and detected a 33-bp deletion in one of them, Os04g0101800. Transgenic plants of the mutant transformed with the genomic fragment carrying the Os04g0101800 sequence from Nipponbare showed normal gravitropic responses and no soil-surface rooting.

Conclusion

These results suggest that sor1, a rice mutant causing soil-surface rooting and altered root gravitropic response, is allelic to Os04g0101800, and that a 33-bp deletion in the coding region of this gene causes the mutant phenotypes.