Mokuzai Gakkaishi
Online ISSN : 1880-7577
Print ISSN : 0021-4795
ISSN-L : 0021-4795
Volume 52, Issue 1
Displaying 1-7 of 7 articles from this issue
Review
  • Yutaka Kitamoto
    2006 Volume 52 Issue 1 Pages 1-7
    Published: 2006
    Released on J-STAGE: January 31, 2006
    JOURNAL FREE ACCESS
    The objective in breeding of edible and pharmaceutical mushrooms is to produce the strain that is suited for commercial production of high quality fruit bodies at lower running cost. The breeding of a new mushroom species is based on the selection of genetic variants that produced fruit bodies of desirable quality and appearance from wild genetic resources. The selected fruit bodies would be used as a source material for the preparation of the next generation of seed spawn by crossing. The breeding of new hybrid strain is performed by the four successive processes as follows : the selection of two parental dikaryons, the production of monokaryotic line stocks from parental dikaryons, the production of various hybrid dikaryons by crossing between the two selected monokaryotic line stocks, and several levels of cultivation tests of the crossing products for selecting superior hybrid. In this review, current progress in research and development of commercial mushroom breeding is introduced.
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Original Articles
  • A comparison with the conventional band dendrometer and the pinning method
    Kana Yamashita, Naoki Okada, Koichi Kamo
    2006 Volume 52 Issue 1 Pages 8-18
    Published: 2006
    Released on J-STAGE: January 31, 2006
    JOURNAL FREE ACCESS
    Radial growth of a sugi(Cryptomeira japonica)and a hinoki(Chamaecyparis obtusa)tree was measured with the newly developed wire dendrometer to compare its performance with those of the conventional band dendrometer and the pinning method. Employing flexible stainless wire and constant tension into the wire dendrometer reduced the problems of the band dendrometer : the first year slack, the friction of the bands, and the increase of the band tension caused by radial stem growth. The wire dendrometer detected the start of xylem growth, a rapid growth period(earlywood formation period)and a slow growth period(latewood formation period), which coincided with the results by the pinning method. However, the wire dendrometer could not detect the end of xylem growth. Since the wire dendrometer detected not only the xylem formation but also the shrinkage and expansion of the trunk caused by water transpiration, it was difficult to detect small amounts of xylem formation or the cessation of cell division. One point measurements such as the dial gauge or the pinning methods could not measure the average radial growth because of the periodical growth variation among the different radii, whereas the wire dendrometer could monitor the average periodical growth of tree trunks.
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  • Instantaneous and total compliance of radial specimens
    Wenbo Zhang, Morihiko Tokumoto, Takashi Takeda, Koh Yasue
    2006 Volume 52 Issue 1 Pages 19-28
    Published: 2006
    Released on J-STAGE: January 31, 2006
    JOURNAL FREE ACCESS
    Mechano-sorptive(MS)creep of wood occurs by the interaction of mechanical stress and moisture sorption. While there are different hypotheses on mechanism of this complicated phenomenon, knowledge on the behavior of wood has been accumulated. As one typical feature, it had been found that MS creep deformation under continuous load was equal to the superposition of additional creep under a single load and recovery under zero-load, and it seems as if wood acts by memorizing the range of moisture change under load. In this study, we focused on the effect of delignification on MS creep of radial specimens, and attempted to clarify the function of the hydrophobic constituent.
    Specimens for bending creep tests were prepared by three different levels of delignification, and untreated specimens were also prepared as controls. Three loading conditions were used:"Ad" cycles(the first adsorption under load, subsequent desorption under zero-load, the next adsorption under load...), "Da" cycles(desorption under load, adsorption under zero-load...), and "AD" cycles under continuous load. Moisture cycles were repeated five times for all processes. The test temperature was constant at 20°C, and the relative humidity ranged from 40% to 94%.
    When the delignification level was high, both instantaneous(J0)and total(JT)creep compliance were large as compared with the control specimens. JT of the high delignification level during the Ad, Da, and AD cycles were 5.1, 4.0, 5.2 times the value of the control specimens, respectively. JT increased sharply as lignin content decreased, but the relationships between JT and J0 were proportional. The estimated JT, which was calculated by superposition of Ad and Da cycles, agreed with experimental data of AD cycles. It was concluded that the effect of delignification on MS creep was quantitatively remarkable, but was qualitatively slight.
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  • Set recovery of radial specimens
    Wenbo Zhang, Morihiko Tokumoto, Takashi Takeda, Koh Yasue
    2006 Volume 52 Issue 1 Pages 29-36
    Published: 2006
    Released on J-STAGE: January 31, 2006
    JOURNAL FREE ACCESS
    As an additional step to explain the mechanism of mechano-sorptive (MS) creep, radial specimens of hinoki (Chamaecyparis obtuse Endl.) were subjected to different levels of delignification, and the effect of delignification on MS creep was investigated. In a previous paper, instantaneous and total creep compliance during five moisture cycles under three loading conditions was discussed. In this study, recovery of set of radial specimens described in the previous paper was investigated, and we also compared the results with recovery of set when subjected to a single adsorption or desorption process.
    The levels of delignification were three: weak (W), moderate (M), and strong (S) as described in the previous paper. Untreated specimens (C) were also prepared as controls. The loading conditions during moisture cycling were three : "Ad" cycle, "Da" cycle, and "AD" cycle under continuous load. For specimens subjected to a single adsorption or desorption process under load, "A" -process specimens were under load during adsorption, and "D"- process specimens were under load during desorption. The range of adsorption or desorption was between 40% to 94%RH. The concentrated bending load was set at midspan of specimens, and deflections were measured at midspan. For the prepared specimens, recovery of set was obtained during adsorption.
    The results were summarized as follows:
    1. While the residual set compliance (JS) after unloading increased by delignification, The ratio of JS of treated specimens to controls was proportional to the ratio of instantaneous compliance. It should be noted that delignification brought to MS mechanism remarkable quantitative change, but the qualitative system was constant.
    2. The recovery of set after adsorption for "Ad" or "A" was small compared to "Da" or "D" for all delignification levels. Recovery of "Ad" or "A" was slow within the moisture-change range for preparation, and became fast beyond the range. For "Da" or "D" the opposite was the case, and "AD" was constant. Recovery of "AD" was consistent with superposition of "Ad" and "Da".
    3. The range of moisture content expanded by delignification, and the upper limit of the range was almost equal to the turning point of recovery curve. The differences of recovery rate before and after the turning point deceased by delignification for "Ad"/"A" set or "Da"/ "D" set.
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  • Fukumi Maki, Tsutomu Aoki
    2006 Volume 52 Issue 1 Pages 37-43
    Published: 2006
    Released on J-STAGE: January 31, 2006
    JOURNAL FREE ACCESS
    The changes in temperature and humidity in various living spaces were observed for about one year. As the windows and doors in any living spaces were mostly closed from 9 : 00 p.m. to 6 : 00 a.m., nighttime changes were small compared with those in the daytime, so that the humidity conditions caused by the interior wall materials could be easily determined. Thus, we went on to compare and examine the changes in temperature and humidity in various living spaces.
    Result shows that in rooms in log and wooden-houses, the average nighttime humidity was 55-70% throughout the year and was comfortable for the inhabitants. On the other hand, in some of the reinforced-concrete-building rooms, the average humidity varied from 38%-78%, a considerable change. And it was also made clear that, when the inhabitants were in, the rooms were kept comfortable with 57%-72% humidity, for some air-conditioners were used and so on.
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  • Effects of komisen insertion and joint drying on the contact stress between end grain of column and still
    Kiho Jung, Kweonhwan Hwang, Kohei Komatsu
    2006 Volume 52 Issue 1 Pages 44-49
    Published: 2006
    Released on J-STAGE: January 31, 2006
    JOURNAL FREE ACCESS
    To understand the stress transmission mechanism in the traditional timber joint, focus was aimed on the contact stress which occurs at the contact surface of mortise and tenon joints. More precisely, the influence of drying shrinkage of members on changes of contact stress at the joint was investigated. A method for continuously measuring changes of the contact stress was developed by placing a small load cell at the interface between the end grain surface of the column and the side grain surface of the sill.
    Two types of komisen (wooden square key) were used :
    Shirakashi(Quercus myrsinaefolia Blume), which is widely used in traditional timber structure, and compressed sugi(Cryptomeria japonica D. Don) which was newly developed with the expectation of allowing the use of softwood as an alternative.
    Insertion of the komisen with different positioning of holes (shifted by 2 mm) together with the bending force, shear and friction of the komisen can be described to enhance the contact stress between members(column and sill in this case).
    Komisen joints made of shirakashi retained a contact stress of 14% (1.1 MPa) after drying for 150 days, with a 10% decrease in weight and a 2% decrease in dimension. Compressed sugi komisen retained a contact stress of 24% (1.5MPa) after 150 days with a decrease in weight and dimension identical to that of shirakashi.
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Note
  • Naomi Nishikawa, Masaki Murayama, Kanichi Kamiya
    2006 Volume 52 Issue 1 Pages 50-54
    Published: 2006
    Released on J-STAGE: January 31, 2006
    JOURNAL FREE ACCESS
    Composite powder materials consisting of activated carbon and TiO2 were prepared through the carbonization of woody waste powders coated with TiO2 gel by using the sol-gel method. The effect of the conditions for preparing TiO2 sols and the carbonization process on the properties of the resulting composites was examined. It was found that the addition of diethanolamine (DEA) to the TiO2 sol was effective for achieving a smooth coating on woody waste-derived activated carbon. The composites obtained by heat-treating the wood powders coated with DEA and polyethylene glycol (PEG)-added TiO2 gel with at 530°C and 700°C exhibited both the adsorption and the photocatalytic decomposition of methylene blue in water.
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