Applicability of effective medium theory to wood density measurements using terahertz time-domain spectroscopy

The use of an effective medium theory is important when accurately measuring wood density using millimeter and terahertz wave techniques. To confirm the applicability of this theory to the evaluation of wood density, the relative permittivity and dielectric loss of oven-dry flat-sawn specimens of 11 different wood species were measured in a frequency range of 0.15–1.2 THz using a transmission measurement system for terahertz time-domain spectroscopy. A mixture model based on the effective medium theory well explained the density dependence of relative permittivity over the entire frequency range, while it did not fully explain that of dielectric loss, especially for higher frequencies. This indicates that wood scatters the terahertz wave with a wavelength close to the transverse sectional dimensions of the pores in wood in the same way as Mie scattering. It was found from the dielectric loss spectrum of wood substance that the frequency around 0.23 THz was preferable for the nondestructive evaluation of wood.     

Ophiostomatoid fungi associated with bark beetles onAbies veitchii in wave-regenerated forests

Relationships between tree mortality and bark beetle infestation onAbies veitchii at the wave-regenerated forest in Mt. Asahi, Okuchichibu area were investigated. Most of the firs with green needles and newly developed current year’s shoots in the dieback zone were heavily infested by bark beetles before the death of the trees. After heavy infestation of beetles, about half of the infested firs died within the year, and the other half died in the next year. When the species composition of bark beetles and associated ophiostomatoid fungi were investigated in Mt. Asahi and also at a typical wave-regenerated forest in Mt. Shimagare, Yatsugatake area,Cryphalus montanus andC. piceae were dominant beetle species for Mt. Asahi and Mt. Shimagare, respectively.Ophiostoma subalpinum andO. europhioides were dominant fungal species at both wave-generated forests. BecauseO. subalpinum was detected more frequently from deeper areas of sapwood thanO. europhioides, it was suggested that the fungal species may accelerate the death of stressed firs in wave-regenerated forests. Contribution No. 169, Laboratory of Plant Parasitic Mycology, Institute of Agriculture and Forestry, University of Tsukuba.     

A method for isolation of milled-wood lignin involving solvent swelling prior to enzyme treatment

Summary A new lignin isolation method has been developed. Wood and pulp were subjected to ball milling, swelled in an organic solvent, and then treated with a cellulase. The enzyme digestion time could be shortened to 1 day with this method. The lignin obtained has been named Swelled Enzyme Lignin (SEL). Swelling and enzyme digestion conditions and their effects on lignins were investigated. The SEL's from wood could be directly washed with water, while those from pulp had to be washed with aqueous acetic acid because they were water soluble. The purification of crude SEL's was accomplished by extracting them with dioxane-water, and then precipitating and washing with ethyl ether. Lignin yields were 24–67% based on the total amount of lignin present. The characteristics of the SEL's were further investigated by gel-permeation chromatography (GPC), infrared and ¹³C nuclear magnetic resonance (NMR) spectroscopy.Symbols SUKP Softwood Unbleached Kraft Pulp - BUKP Birch Unbleached Kraft Pulp - TD Todomatsu (Abies sachalinensis) wood - MWL Milled Wood Lignin - MWLS (BK, TD) Milled Wood Lignin of SUKP (BUKP, TD) - SEL-C Swelled Enzyme Lignin (crude) - SELS-C SEL-C of SUKP, other materials named in the same way - SELS-90 SEL-C of SUKP and extracted with 90% dioxane-water - SELS-96 SEL-C of SUKP and extracted with 96% dioxane-water, other materials named in the same way     

Investigations on Cambodian soils

Basic information on the nature of soils, their potentialities, and their limitations is necessary to evaluate Cambodian agriculture properly, and to develop a program for increasing food and other crops. Suitable information has, however, been limited, especially as there is not to be found in any report much data relating to soils of different origins over the whole country. There is, needless to say, some information on confined areas of Cambodia.     

Effect of bensulfuron-methyl (a sulfonylurea herbicide) on the soil bacterial community of a paddy soil microcosm

The effect of bensulfuron-methyl (BSM) on a soil microbial community in a model paddy microcosm was studied. Total bacterial numbers in the overlying water and surface soil were monitored for 2 months after the application of BSM at the field rate and a ten-fold field rate. Pentachlorophenol (PCP) was used for comparison. Neither chemical affected the total bacterial numbers remarkably, either in the overlying water or in the surface soil. In contrast, the nitrification potential was significantly suppressed by the BSM application. The bacterial community structure, as evaluated by the denaturing gradient gel electrophoresis (DGGE) of PCR amplification products from bacterial 16S rDNA, was unaffected by the BSM treatments over 8 weeks in the surface soil, compared with the control (no pesticide). In contrast, the surface soil exposed to PCP at a ten-fold field rate showed different patterns from the controls at 4 weeks and 8 weeks after application. The DGGE patterns of the overlying water were much more variable than those of the surface soil in any treatments. Cluster analysis showed that the BSM plots were classified within the same group as the control at 1 week after application and that the BSM and PCP plots from 2 weeks onward after application were grouped differently from the control. Of 22 clones excised from the DGGE gels, 20 clones belonged to the Proteobacteria and two belonged to the Verrucomicrobia. It was considered that the impact of BSM on the overall microbial community (total numbers, community structure of soil) was negligible, although BSM had an impact on some specific functions of the soil microbial community (nitrification) and a part of the community (overlying water).     

Extraction of silver from soils by chloride solutions

Using chloride solutions as extractants, 6.4–18.4% of Ag were extracted from polluted Annaka and Fuchu soils, whereas only 0.06–0.08% Ag were extractable using NH₄OAc, NH₄NO₃ or (NH₄₎₂SO₄ solution. In the case of unpolluted Konosu and Nagano soils, 28.3–47.0% of Ag were extracted by KCl and 0.7–1.0% of Ag were by NH₄OAc. The silver extracted with chloride solution was assumed to be derived from residual fractions.     

The effects of traffic on the raccoon dog (Nyctereutes procyonoides viverrinus) and other mammals in Japan

We investigated the extent of raccoon dog roadkills, and the factors influencing them, using data from the National Expressways in Japan for 1987-1998. A high rate of raccoon dog roadkills occurred in western Japan, whereas a relatively low rate was typical of the central region and of Hokkaido. Kills on the National Expressways increased as traffic and the length of the road network increased between 1987 and 1998. The relationship between mortality and traffic volume was scale-dependent. The number of roadkills was positively correlated with traffic volume at national level, but negatively correlated with the amount of traffic along sections of an individual major road between exits. There were spring and autumn peaks, and possibly early morning and evening peaks, of mortality. Mortality was higher for roads in a cutting, where the road was closer to water, and where the roadside habitat was broad-leaved woodland. Coniferous forest was negatively associated with roadkills. The total numbers of roadkills on four types of roads (National Expressways, National, Prefectural, and Municipal roads), was estimated to be between 110,000 and 370,000 in 1998. We suggest some preventative measures which might mitigate road casualties (while remaining attentive to human safety). Roadkill data, after controlling for traffic volume, can be useful as a population trend index. Patterns for racoon dogs are compared with those for other species.     

Changes in the concentrations of acrylamide, selected odorants, and catechins caused by roasting of green tea

This research aims to optimize roasted green tea (Houjicha) processing by using roasting treatments to achieve acrylamide mitigation without compromising the quality. 2-Ethyl-3,5-dimethylpyrazine and 2-ethyl-3,6-dimethylpyrazine were identified as potent odorants by aroma extract dilution analysis. In preliminary sensory experiments, the desirable Houjicha flavor was produced in products roasted at 160 degrees C for 30 min and at 180 degrees C for 15 min. Under these conditions, potent odorants were formed at levels adequate for contributing to the Houjicha flavor. Acrylamide amounts in tea infusions were 2.0 and 4.0 microg/L by roasting at 160 degrees C for 30 min and at 180 degrees C for 15 min, respectively. Compared to roasting at 180 degrees C, the degradation of tea catechins was suppressed by roasting at 160 degrees C. Hence, roasting at 160 degrees C for is recommended for Houjicha processing for acrylamide mitigation, formation of potent odorants, and suppression of degradation of tea catechins.     

Stability and emulsion-forming ability of water-soluble fish myofibrillar protein prepared by conjugation with alginate oligosaccharide

Carp myofibrillar protein (Mf) was conjugated with alginate oligosaccharide (AO) through the Maillard reaction under low relative humidity, and the functional properties of the Mf-AO conjugate were investigated under different NaCl concentrations and pH levels. Mf became highly solubilized at lower NaCl concentrations by conjugation with AO, with a slight loss of available lysine. The thermal stability of Mf was effectively improved by conjugation with AO. Heat treatment at 80 degrees C for 2 h had no effect on the solubility of the Mf-AO conjugate attached to 227 microg/mg of AO regardless of the NaCl concentration and pH. Furthermore, the Mf-AO conjugate showed excellent emulsion-forming ability regardless of NaCl concentration. The improved functionalities of Mf by conjugation with AO remained even at a nearly isoelectric point. These results indicate that conjugation with AO through the Maillard reaction is an effective way to prepare high-functional food material from fish muscle protein.     

Artificial infection by transplantation of juvenile Fasciola worms into the abdominal cavity of rats

Rats were successfully infected with Japanese Fasciola sp. by transplantation of juvenile worms (JW) or metacercariae (MC) into the abdominal cavity. Moreover, the rat was investigated on its suitability for different experiments with liver flukes. JWs or MCs transplanted intraperitoneally (IP) matured in the bile duct of rats. Moreover, more stable infections were established by inoculation of JWs than MCs. About 3 of 10-15 JWs transplanted into the abdominal cavity of a rat matured and laid eggs in the bile duct. The mean prepatent period was 63.5 days in the JW inoculated group. EPG values were kept constant at a level of 10(2)-10(3) about 100 to 230 days after the transplantation of JWs. The life span of Japanese liver flukes was estimated to be about 400 days in rats. From these results, it was concluded that the rat is suitable for various experiments with Fasciola sp.