Effect of particle shape on linear expansion of particleboard

Hinoki (Japanese cypress) strand with 0.6mm thickness was hammer-milled to prepare three types of particles that had the same thickness but different lengths and widths. Screen analysis and image analysis were conducted to evaluate the shape and distribution of the particle dimensions. Laboratory-scale particleboards were fabricated at three density levels using these particles. To determine the true effect of particle shape on the linear expansion (LE) of the board, these boards exhibited almost the same temperature behavior during pressing, the same density profile, and the same bending properties at each board density level. LE at 40°C and 90% relative humidity of the board was found to be affected by the particle shape. The board composed of small particles showed a larger LE at the same density level. It was considered that the out-of-plane orientation angle of the particles affected the LE of the boards. Thickness swelling and internal bond strength were also affected by the particle shape.Part of this report was presented at the 50th annual meeting of the Japan Wood Research Society, Kyoto, April 2000     

Evaluating the durability of wood-based panels using internal bond strength results from accelerated aging treatments

In this study, the durability of wood-based panels was evaluated by comparing the internal bond (IB) strength retention after five different laboratory-based accelerated aging tests with the IB retention after 5 years of outdoor exposure in Shizuoka City. In each accelerated aging test, the IB retention of MDI-bonded panels showed high retention compared to other panels. Outdoor exposure in Shizuoka City resulted in an IB retention value for particleboard (PF) and oriented strandboard (aspen) of less than 10% after the 5-year exposure period. Medium-density fiberboards maintained their initial IB strength over the same period. Calculation of the mean IB retention for all board types allowed comparison of the severity of aging between the accelerated test methods and outdoor exposure. The ASTM six-cycle test method was the most severe among the standard treatment cycles applied.     

Nonrandom distribution of chum salmon stocks in the Bering Sea and the North Pacific Ocean estimated using mitochondrial DNA microarray

More than 1,000 age-identified chum salmon Oncorhynchus keta collected at 23 stations in the Bering Sea and the North Pacific Ocean in June to July 2003 were used to estimate their origin of stocks using a DNA microarray developed for analyzing the mitochondrial (mt)DNA haplotypes. The observed haplotype distribution was nearly the same as that reported previously for fish collected in September 2002 and 2003 in the present surveyed areas. A conditional maximum-likelihood method for estimation of stock compositions indicated that the Japanese stocks mainly distributed in north central Bering Sea, whereas the Russian stocks were mainly in western Bering Sea. The North American stocks were abundant in eastern Bering Sea and around the Aleutian Islands. Such an area-specific stock composition was not significantly different between mature and immature fish. Thus, the combined results of 2 years suggest that the distribution of chum salmon is nonrandom in the surveyed areas in summer and autumn, and that fish of the same origin migrate together to the same area irrespective of age.     

Phylogenetic identification of Cystoisospora spp. from dogs, cats, and raccoon dogs in Japan

Cystoisospora spp. from feces in dogs, cats, and raccoon dogs were isolated, sequenced at the small subunit ribosomal RNA gene locus and compared to other Cystoisospora spp. Cystoisospora oocysts from dogs and raccoon dogs were morphologically similar with those of C. ohioensis, and cat isolates were similar with those of C. felis. The sequences from dogs and raccoon dogs, and cats have a homology with C. ohioensis and C. felis, respectively. Phylogenetic analysis of the DNA sequences showed that the dog and raccoon dog isolates were nested in a clade with other Cystoisospora spp. including C. ohioensis, C. belli, and C. orlovi. The cat isolate formed a sister group with C. felis that was a separate clade from the dog and raccoon dog group. We report sequence variation in these Cystoisospora sequences and have identified raccoon dogs as another carnivore host for Cystoisospora spp. infecting dogs.     

Recovery of the everted cystacanth of seven acanthocephalan species of birds from feral raccoons (Procyon lotor) in Japan

Acanthocephalan everted cystacanths were detected in the intestines of 61 out of 555 feral raccoons (Procyon lotor) trapped between May 2003 and April 2005 in the western region of mainland Japan (Honshu). All collected specimens were identified as the species of birds including 3 Centrorhynchus species (C. bazaleticus, C. elongatus, and C. teres), Sphaerirostris lanceoides, Plagiorhynchus ogatai, Porrorchis oti, and Southwelina hispida. Three species, C. bazaleticus, C. teres, and S. lanceoides, were new to distribution records in Japan and the Far East. Recovery rates of these acanthocephalans were higher from the raccoons trapped in spring and early summer (range 8.3-36.8%, average 21.5%) than during the remainder of the year (range 0-20.0%, average 6.3%). The reason for this seasonal change is unknown. There is little information on the acanthocephalan fauna of wild birds in Japan, however, recovery of the cystacanths from the feral raccoons captured through the year might provide useful information on the fauna and geographical distribution of avian acanthocephalans.