The Journal of Silk Science and Technology of Japan
Online ISSN : 1881-1698
Print ISSN : 1880-8204
ISSN-L : 1880-8204
Volume 26
Showing 1-10 articles out of 10 articles from the selected issue
Treatise
  • Yoshikazu Hirakawa, Izumi Tsuneyama, Noriko Iida, Satomi Ikejima, Yuji ...
    2018 Volume 26 Pages 5-11
    Published: 2018
    Released: March 10, 2018
    JOURNALS FREE ACCESS

    This study was conducted to develop raised fabric, resembling that woven using long domestic silk fiber for Western style, by application of raising-technique developed for fabrics made of synthetic fibers. Five quantities of raised fabrics were woven from silk threads of different sizes and quality from different silkworm races maintained at the Institute of Sericulture (The Dainippon Silk Foundation). Samples of the fabric were used for the test trials. The raising processing of silk fabric comprised six processes conducted in the order of softening, emery-raising, raising, shirring, polishing, and finishing. A drum with needles on the raising machine was operated at double the speed used for raising cashmere fabrics; moreover, only weft threads of the silk fabric were raised.Results show that the feel of the raised silk fabric was estimated as “the highest grade” using the Kawabata Evaluation System test (KES). The tensile strength and the tear strength of the fabric were greater than those of high-grade cashmere fabrics. Furthermore, a silk coat was made of the raised silk fabric in western style, with a beaver finish. The coat was solid, with high quality and with luster peculiar to silk.

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  • Yutaka Kawahara, Shouhei Okamura, Hiroyuki Wakizaka
    2018 Volume 26 Pages 13-20
    Published: 2018
    Released: March 10, 2018
    JOURNALS FREE ACCESS

    Gel-like liquid silk separated from the middle division of the middle silk gland was immersed in room temperature water for various time periods, and the subsequent dissolved fractions of the liquid silk were used to produce aerogels with different fibroin and sericin contents. Then, the re-dissolvability of the aerogels in water at 50 °C was measured. The aerogels rich in sericin showed poor re-dissolvability. Alternately, the re-dissolvable fraction showed a peculiar amino acid composition that was quite different from fibroin, sericin, and other functional minor protein fractions. This unknown silk protein fraction could promote the dispersion of fibroin into water.

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  • Yusuke Kambe, Yasushi Tamada, Tsunenori Kameda
    2018 Volume 26 Pages 21-30
    Published: 2018
    Released: March 10, 2018
    JOURNALS FREE ACCESS

    We investigated the effects of the addition of buffers (pH 7.4 at 25°C) to a silk fibroin (SF) aqueous solution containing 1% (v/v) dimethylsulfoxide on the formation of a SF spongy structure obtained using a single freeze/thawing of the solution. The addition of a sodium phosphate (a mixture of Na2HPO4 and NaH2PO4; SP) buffer made the SF spongy structure finer and harder dose-dependently, showing the minimum pore size and maximum tensile modulus at 80 mM. In contrast, tris(hydroxymethyl)aminomethane, 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid, and 3-(N-morpholino)propanesulfonic acid buffers inhibited the SF sponge formation. We infer that the salting in/out effect of ions in buffers affected the SF sponge formation; HPO42- and H2PO4- from SP might be strongly hydrated to make SF proteins assemble by hydrophobic interaction. Because the buffering effect of SP is reportedly insulated from the influence of temperature, the pH of the SF solution was expected to be maintained as around 7.4 during the freeze–thawing process to form the SF sponge. The addition of the SP buffer to the SF solution was likely to maintain the activity of SF proteins modified with pH-sensitive bioactive proteins, even after fabrication into the spongy structure. Furthermore, the resulting SF sponge might show high mechanical properties. Because recent advances in transgenic silkworm technology have enabled the production of recombinant SF protein fused to bioactive proteins, the findings in this study are applicable in the formation of bioactive SF sponges to be used as scaffolds for tissue engineering.

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  • Tsukie Izuhara, Takeshi Shirota, Yuji Mochida, Akira Kurioka
    2018 Volume 26 Pages 31-40
    Published: 2018
    Released: March 10, 2018
    JOURNALS FREE ACCESS

    Raw silk and silk fabric used for kimonos have been studied, but few studies have examined their use in Western clothes. Therefore, for eight silkworm race varieties, breeding, cocoon drying, and reeling were conducted in this study under identical conditions. Various tests were conducted under identical conditions of refining and twisting of the material yarn, yarn thickness, weaving structure, etc.

    First, a sensory evaluation test was conducted with yarn, but it was difficult for clothing experts to evaluate threads. Preliminary results indicated that evaluation with fabric is suitable for more accurate evaluation.

    Next, sensory fiber tests and evaluation tests of fabrics woven under the same conditions were conducted using various instruments. Results of the sensory evaluation tests revealed the silkworm varieties that were most suitable for European clothing production. The silk had characteristics of retention of three-dimensional form, softness, lightness, and wrinkle resistance. It can be said that silk characteristics required for Western clothes are silk fabrics with stiffness to retain their three-dimensional form, softness, and wrinkle resistance. Finally, after selecting four fabrics corresponding to silkworm varieties, we made blouses having the same pattern. Results of sensory evaluation tests of the prototyped blouses clarified that differences of the forms of the blouse derive from silkworm variety fiber characteristics. Results also clarified the characteristics that are necessary for Western clothing.

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  • Tetsuya Iizuka, Ken-ichi Nakajima, Eiji Okada
    2018 Volume 26 Pages 41-46
    Published: 2018
    Released: March 10, 2018
    JOURNALS FREE ACCESS

    This study investigated the feasibility of using an evaporative cooling system to improve silkworm rearing house conditions. The inside air temperature was 3 °C lower than the open-air temperature in the silkworm rearing house obtained using a mist cooling system. When using a portable pad-and-fan cooling system, the half-room temperature was 2.5 °C lower. By contrast, when using the two portable pad-and-fan cooling system, the whole-room temperature was 4 °C lower. However, the temperature at a distance from a portable pad-and-fan cooling system was 1 °C higher than it was near the system. The relative humidity increased to 80% under these evaporative cooling systems in the silkworm rearing house, with no harmful effect observed on silkworm rearing. Therefore, these evaporative cooling systems indicate the possibility of preventing high-temperature injury during silkworm rearing.

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