Manufacture of strand board made from construction scrap wood

The objective of this research was to evaluate the physical and mechanical properties of strand board made from construction scrap wood. The strand board was manufactured using Sugi (Cryptomeria japonica D. Don) and Douglas-fir (Pseudotsuga japonica) strands selected from construction scrap wood. The strands were oriented, and three-layer (face/core/face) strand board of three types was produced: one in which the strands of the face layer were oriented at a right angle to those of the core layer (R board), another in which the strands of the face layer were oriented parallel to those of the core layer (P board), and a third in which the strands of both layers were oriented at random (Ra board). The physical and mechanical properties of the boards were evaluated based on Japanese Industrial Standard (JIS). The main results obtained are as follows: the bending strength of the strand board with a density larger than 0.55 g/cm³ exceeded the standard value of type 18 particleboard of JIS A 5908. The bending strength of the strand board was affected by board density, strand orientation and resin content, and became larger with increased density as well as resin content. That of the parallel specimen of P board was the largest among the specimen-orientations and types. The internal bond strength of the strand board with a density larger than 0.55 g/cm³ exceeded the standard value of type 18 particleboard and type 24-10 particleboard of JIS A 5908. The internal bond strength was markedly affected by the resin content of the core layer, and became larger with increased density. The thickness swelling of the strand board decreased with increased resin content, and become larger with increased density.     

Spider silk has an ice nucleation activity

Several ice nucleating substances have been identified, which exist in vivo or can be extracted from biological materials. Spider silk, which has a strong ability for water condensation, has also been found to possess an ice nucleation activity. The freezing temperature of water droplets was higher in the presence than in the absence of spider silk. Moreover, by means of environmental scanning electron microscopy, it was observed that the activity is not due to foreign matter attached to the silk but to the silk fibroin itself.     

Distribution and behaviour of persistent organochlorine insecticides in paddy soil and sediments in the tropical environment: a case study in South India

Paddy soil and sediment samples collected from the Vellar River watershed, Tamil Nadu state, South India from December, 1987 to January, 1989 were analysed to understand the comprehensive behaviour of organochlorine insecticides (HCH and DDT) in the tropical environment. HCH (BHC) showed higher levels in soil during wet season, reflecting the application of technical HCH largely during the flowering season of rice. On the other hand, DDT residues were low and did not show a significant seasonal trend in soil or sediment, indicating small quantities of DDT utilized at present for agricultural purposes in India. When compared to soil, the residue levels in sediments are low and the seasonal variation is less pronounced. This indicates that in tropical watersheds, the relative flux of residues into the aquatic environment is smaller than the amount volatilized to the atmosphere.     

Sex-specific maternal effect on egg mass,laying order,and sibling competition in the Bengalese finch (<Emphasis Type="Italic">Lonchura striata</Emphasis> var. <Emphasis Type="Italic">domestica</Emphasis>)

Maternal effects, such as investment in eggs, have profound effects on offspring fitness. Mothers are expected to skew their investment depending on the laying order and sex when unequal sibling competition occurs within a brood because of sex-specific vulnerability and age hierarchy caused by asynchronous hatching. The Bengalese finch hatches asynchronously and shows a moderate reversed sexual size dimorphism. However, contrary to commonly accepted assumptions of size-dependent vulnerability, the smaller sex (male) is more vulnerable to developmental stress caused by sibling competition. We investigated whether maternal investment would be biased by the position in laying order and the sex of eggs, and also explored the possible differences in growth patterns depending on sex, laying order, and age hierarchy by observing chicks fostered to experimentally manipulated broods where brood composition was controlled and age hierarchy was more enhanced than in natural breeding conditions. We found that overall patterns of maternal investment favored the disadvantageous sectors of sibling competition, i.e., eggs of later laying order and sons over those of early laying order and daughters. We also examined the effect of laying order on adult body size and sex differences in growth patterns. When reared in the subordinate age hierarchy, females could compensate for the deficit of decreased growth rate by taking longer to mature, whereas males could not. We suggest that this sex-specific growth pattern could be the cause of sex differences in vulnerability to early developmental stress.     

Early ontogenetic effects on song quality in the Bengalese finch (<Emphasis Type="Italic">Lonchura striata</Emphasis> var. <Emphasis Type="Italic">domestica</Emphasis>): laying order,sibling competition,and song syntax

Birdsong differs from other sexual traits in that the acquisition process involves learning. Especially in close-ended learning species like the Bengalese finch, conditions experienced during the critical song-learning period can have a profound influence on song quality. Therefore, to understand song evolution from a life-history perspective, we investigated early ontogenetic effects on song quality. In particular, we focused on maternal effects and sibling competition. In asynchronously hatching bird species, the age hierarchy among nestlings affects physical development due to competition for food; mothers may influence this competition by adjusting their investment in each egg according to its sequence in the laying order. To independently assess these effects, chicks of the Bengalese finch were cross-fostered so that the age hierarchies formed in fostered broods were independent of the laying order. Our results indicate that song quality partially reflects early ontogenetic conditions, whereas song duration and note-type repertoire were independent of either laying order or age hierarchy. The syntactical complexity of note order declined over the laying sequence. This finding suggests that the song learning ability is influenced by within-clutch variation in maternal investment toward eggs. Considering that song syntactical complexity is subject to female preference in the Bengalese finch, it is likely that maternal resource allocation strategies play a role in song evolution.     

Plant origin of Okinawan propolis: honeybee behavior observation and phytochemical analysis

Propolis is a natural resinous product collected by honeybees from certain plants. It has gained popularity as a food and alternative medicine. Poplar and Baccharis are well known as the source plants of European and Brazilian propolis, respectively. However, the propolis from Okinawa, Japan, contains some prenylflavonoids not seen in other regions such as Europe and Brazil, suggesting that the plant origin of Okinawan propolis is a particular plant that grows in Okinawa. To identify the plant origin of Okinawan propolis, we observed the behavior of honeybees as they collected material from plants and caulked it inside the hive. Honeybees scraped resinous material from the surface of plant fruits of Macaranga tanarius and brought it back to their hive to use it as propolis. We collected samples of the plant and propolis, and compared their constituents by high-performance liquid chromatography with a photo-diode array detector. We also compared their 1,1-diphenyl-2-picryl-hydrazyl radical scavenging activity. The chemical constituents and biological activity of the ethanol extracts of the plant did not differ from those of propolis. This indicates directly that the plant origin of Okinawan propolis is M. tanarius. S. K. and J. N. contributed equally to this work.