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621.
622.
In the present paper the attention is focused on the relation between vortex shedding phenomena andacoustic resonance which occurred in the two-dimensional model of boiler.There were tube bankswith in-line arrangement for small tube pitch ratio.We measured the sound pressure level,the phasedelay of acoustic pressures,the spectrum of velocity fluctuation and the gap velocity.As a result, wefound two peak frequencies of sound pressure level with different Strouhal numbers S_t,mainly about0.26 and 0.52.The noise of S_t=0.26 was the resonance of transverse mode and S_t=0.52 waslongitudinal mode.The vortex shedding of S_t=0.15 was generated inside the tube banks withoutacoustic resonance. As gap velocity increased, we observed that the peak level of spectrum was weakand broad-banded. The onset velocity of the acoustic resonance of longitudinal mode was lower thanthat of transverse mode. 相似文献
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Prof. Dr. Yoshitsugu Akiyama Kazunori Kimura Dr. Syuuhei Komatsu Dr. Tohru Takarada Prof. Dr. Mizuo Maeda Prof. Dr. Akihiko Kikuchi 《Chembiochem : a European journal of chemical biology》2023,24(1):e202200451
A colorimetric assay of DNA cleavage by bleomycin (BLM) derivatives was developed utilizing high colloidal stability on double-stranded (ds) DNA-modified gold nanoparticles (dsDNA-AuNPs) possessing a cleavage site. The assay was performed using dsDNA-AuNPs treated with inactive BLM or activated BLM (Fe(II)⋅BLM). A 10-min exposure in dsDNA-AuNPs with inactive BLM treatment resulted in a rapid color change from red to purple because of salt-induced non-crosslinking aggregation of dsDNA-AuNPs. In contrast, the addition of active Fe(II)⋅BLM retained the red color, probably because of the formation of protruding structures at the outermost phase of dsDNA-AuNPs caused by BLM-mediated DNA cleavage. Furthermore, the results of our model experiments indicate that oxidative base release and DNA-cleavage pathways could be visually distinguished with color change. The present methodology was also applicable to model screening assays using several drugs with different mechanisms related to antitumor activity. These results strongly suggest that this assay with a rapid color change could lead to simple and efficient screening of potent antitumor agents. 相似文献
626.
Shengfang Shi Hideki Hashimoto Tohru Sekino 《International Journal of Applied Ceramic Technology》2023,20(3):1774-1784
This work investigates the effects of content ratio Co3+/Co2+ on piezoelectric properties of lead-free Ba0.88Ca0.12Zr0.12Ti0.88O3 (BCZT) ceramics. For this purpose, 0.10 wt% Co ions using a CoO powder doped BCZT ceramics were sintered under various atmospheres (ranging from pure nitrogen to 100 vol% oxygen concentration) to vary the ratio value Co3+/Co2+. X-ray photoelectron spectroscopy analysis revealed the coexistence of Co3+ and Co2+ for oxygen concentration below 40 vol% and the single oxidation state of Co3+ for oxygen concentration over 50 vol%. Co2+ substitution could induce more oxygen vacancy to accelerate densification and grain growth, whereas Co3+ substitution usually leads to larger lattice distortion to generate a stable asymmetric structure. When oxygen concentration was 30 vol% and Co3+/Co2+ near to 1.0, the respective superiority of Co3+ and Co2+ is brought into full play, and the ceramic showed the highest piezoelectric constant d33* ∼ 518 pm/V (380 pm/V for undoped BCZT) and the relatively high Curie temperature Tc ∼ 105°C (95°C for undoped BCZT). This study suggests that optimizing sintering atmosphere might be an effective way to enhance the piezoelectric properties for some composition-modified piezoelectric BCZT ceramics. 相似文献
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628.
Wanlu Xiao Dr. Yasuharu Satoh Dr. Yasushi Ogasawara Prof. Dr. Tohru Dairi 《Chembiochem : a European journal of chemical biology》2022,23(12):e202100705
Salinipeptins belong to the type-A linaridin class of ribosomally synthesized and post-translationally modified peptides (RiPPs) comprising 22 amino acid residues with multiple D -amino acids. Although chirality of other type-A linaridins, such as grisemycin and cypemycin, has not been reported, the biosynthetic gene clusters of type-A linaridins have identical gene organization. Here, we report heterologous expression of grisemycin biosynthetic gene cluster (grm) and show that grisemycin contains multiple D -amino acids, similar to salinipeptins. The heterologous expression experiments also confirm the involvement of a novel peptide epimerase in grisemycin biosynthesis. Gene-deletion experiments indicate that grmL, a single gene with unknown function, is indispensable for grisemycin production. We also show that the presence of D -amino acids is likely a common feature of linaridin natural products by analyzing two other type-A linaridin clusters. 相似文献
629.
Tohru Morii Hiroyuki Hamada Zen-Ichiro Maekawa Toshio Tanimoto Takahiro Hirano Kazushi Haruna 《Polymer Composites》1995,16(3):240-249
This study deals with the degradation of mechanically-fastened GFRP joints immersed in hot water (80°C). The material used was randomly oriented E-glass fiber continuous strand mat with a crosslinked polyester. Three kinds of joint geometries were adopted; thickness was 3 mm, hole diameter was 6 mm, the distance from hole center to top-edge was 18 mm (3e), and specimen widths were 18 (3w), 30 (5w), and 42 mm (7w). Failure modes of original dry specimens were a function of joint geometry, The dominant failure mode of 3w3e joints was net-tension, whereas 5w3e and 7w3e joints displayed bearing failure. As degradation progressed, the dominant failure mode gradually shifted from net-tension to bearing failure. Strength reduction was marked in 5w3e and 7w3e joints, in which the dominant failure mode was bearing. Joint strength and failure mode were predicted from the combination of a macroscopic failure criterion and characteristic curves obtained from tensile testing of rectangular specimens with holes, bearing tests, and finite element analysis. Predictions agreed with experiment. 相似文献