Journal of Fiber Science and Technology
Online ISSN : 2189-7654
ISSN-L : 2189-7654
Volume 79, Issue 5
Displaying 1-3 of 3 articles from this issue
Transaction
  • Bai Mingxue, Daisuke Asai, Takuro Koshikawa, Hiromu Takemura, Kensuke ...
    Article type: Transaction
    2023 Volume 79 Issue 5 Pages 101-111
    Published: 2023
    Released on J-STAGE: May 26, 2023
    JOURNAL FREE ACCESS
    Supplementary material

    Three sulfated 1-alkyl-triazole-maltoheptaosides bearing long-chain alkyl groups (C6, C12, and C18) at the reducing ends were synthesized and subjected to surface plasmon resonance with liposomes to elucidate the cytotoxic mechanism of sulfated alkyl oligosaccharides having potent anti-HIV activity. With increasing the length of the alkyl groups, the cytotoxicity of nonsulfated and sulfated 1-alkyl-triazole-maltoheptaosides against MT-4 cells increased to CC50 values of 102 and 72 μg/mL from a low cytotoxicity of CC50>1000 μg/mL. Nonsulfated and sulfated 1-alkyl-triazole-maltoheptaosides bearing a C18 alkyl chain showed the highest apparent association-rate constant (ka=1.20×105 and 1.00×107 1/M, respectively) and lowest dissociation-rate constant (kd=7.30×10‒7 and 1.39×10‒4 1/s, respectively) constants with the liposomes, indicating that the alkyl groups bearing longer-chains interact tightly with the liposomes. The results suggest that the longer-chain alkyl groups penetrate into the lipid bilayer of MT-4 cells to induce cytotoxicity. Considering the proposed cytotoxic mechanism, the antibacterial activity of the 1-alkyl-triazole-maltoheptaosides against Gram-negative Escherichia coli and Gram-positive Bacillus subtilis was preliminarily investigated, finding certain antibacterial activity.

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  • Akihiro Hideno, Tomoki Yabutani, Tomonori Sugiyama, Noriyoshi Nishida ...
    Article type: Transaction
    2023 Volume 79 Issue 5 Pages 112-123
    Published: 2023
    Released on J-STAGE: May 26, 2023
    JOURNAL FREE ACCESS

    Cellulose nanofibers (CNFs) which are extremely small fibers with a width of several nm comprising mainly crystalline cellulose. They are a promising material with many superior characteristics in a wide range of industrial fields, and have been developed by domestic and foreign paper mill companies. CNF slurry with a high water content (> 98%) is usually supplied because CNFs are generally produced through pulp nanofibrillation in a relatively large volume water. Dewatering of CNF slurry is an important issue because this process affects various processes such as shipping, drying, and product developments. To dehydrate and concentrate CNF with a high-water retention efficiently, the original dewatering CNF method with multiple wires was used in this study. First, the CNFs obtained by mechanical nanofibrillation were prepared using a grinder from Laubholz bleached kraft pulp (LBKP). The fibers with a nano-scale width and a micro-scale fiber network were observed in the prepared CNF slurry. Furthermore, flocculation and dispersion in CNF slurry occurred. Second, the initial solid concentration of CNF slurry, wire opening, and number of wire stacks affected the CNF dewatering in the static and batch tests. In this test, a recovery yield (retention) of 87.7% and concentration to 9.5% were achieved using three stacked wires from CNF slurry of 1.7%. Third, the laboratory-scale apparatus for dynamic CNF dewatering was constructed assuming the practical continuous manufacturing machine, and applied. The gradual suction; combining weaker suction (5 kPa) with multiple wires in the early stage and stronger suction with a single wire in the later stage, was the most effective for dewatering CNF using metal wires. However, multiple wires and the combination of weaker suction in the early stage and stronger suction in the later stage were suitable for dewatering CNF using plastic wires. Ultimately, 98% retention a solid concentration of 9.9% were achieved in the dynamic tests using multiple plastic wires.

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  • Yuki Mashiyama, Yuka Hasunuma, Atsuhiro Fujimori
    Article type: Transaction
    2023 Volume 79 Issue 5 Pages 124-131
    Published: 2023
    Released on J-STAGE: May 26, 2023
    JOURNAL FREE ACCESS

    Among the functionalities exhibited by nanofibers, gelation/thixotropic properties arise from the solvent used. We clarified the selectivity of solvents for the gelation of nanofibers formed by diamide-based thixotropic additive molecules with two hydrocarbon chains. Chiral thixotropic additive molecules that form helical nanofibers tended to gel more efficiently in the same solvent compared to achiral straight nanofibers. These diamide groups with two hydrocarbon chains did not develop gelation ability in non-polar normal alkanes or solvents with low solubility owing to poor fiber development. In addition to that of the phenyl-based solvent, when the amount of the gelation solvent was increased, the entanglement density of the nanofibers decreased and consequently, the gelation ability tended to gradually decrease. These results support the conventional hypothesis, according to which the origin of solvent gelation is the efficient entrapment of solvent molecules into the tangled tissue of fibers.

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