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한래희,김창민,우상우,정기영,Takehiro Hirose 한국지질과학협의회 2020 Geosciences Journal Vol.24 No.4
The Suryum fault is an active fault in southeast Korea crosscutting the Quaternary sediment deposit. We conducted outcrop-scale to microscale observations of the fault slip zone and performed shear experiments on the fault gouge at subseismic (3–30 μm/s) and seismic slip rates (0.53 m/s). The gouge is rich in clay minerals (> 58%), particularly in expandable clay minerals (40%). In the gouge zone, a very narrow (20–150 μm thick) principal slip zone (PSZ), identified by the strong alignment of clay minerals, was developed. At several places along the fault, the gouge is observed to have been injected into the Quaternary wallrock sediments. The development of the narrow PSZ is incompatible with the velocity-strengthening behavior of the Suryum fault gouge observed in the shear tests, and it may indicate that seismic rupture could be propagated along the PSZ in the clay-rich gouge. Slip localization into the PSZ was presumably possible because of significant dynamic fault weakening due to thermal pressurization (or buildup of pore pressure caused by frictional heating) in the low-permeability clay gouge during fast slip. The gouge injections along the Suryum fault may be the geological record of gouge fluidization caused by thermal pressurization. This idea is supported by observations of very low friction of the Suryum fault gouge when sheared experimentally at the seismic slip rate and of the gouge injections in the sheared gouge. The dynamic weakness of the Suryum fault implies that large displacement and low-frequency ground motion at near-surface depths would be possible when it is reactivated.
Carbon-forming reactions under a reducing atmosphere during seismic fault slip
Oohashi, Kiyokazu,Han, Raehee,Hirose, Takehiro,Shimamoto, Toshihiko,Omura, Kentaro,Matsuda, Tatsuo Geological Society of America 2014 Geology Vol.42 No.9
<P>Graphite is a well-known solid lubricant and can be as important as clay minerals in reducing the frictional strength of faults. Some natural fault zones contain carbonaceous material (CM) even where host rocks do not contain it, and seismic fault motion can promote the graphitization of low-grade CM. Thus, the origin of CM in fault zones is an important issue in fault mechanics. Previous high-velocity friction experiments have revealed various chemical reactions in fault zones during seismic fault motion, but most experiments have been conducted in an atmosphere under oxic conditions. Here we report experimental results on Carrara marble (free of CM), conducted under N<SUB>2</SUB> or H<SUB>2</SUB> atmospheres at a slip rate of 1.3 m/s and normal stresses of 2.0–3.1 MPa. A small amount of blackish material formed in generated gouge only under reducing conditions with the H<SUB>2</SUB> atmosphere, and Raman spectroscopic analysis revealed the presence of CM (amorphous carbon) in the material. The CM is attributable to (1) the generation and pyrolitic dissociation of CH<SUB>4</SUB>, and/or (2) a reduction reaction of emitted CO<SUB>2</SUB> due to calcite decomposition. We confirmed the formation of CH<SUB>4</SUB> using gas chromatography. The CM produced in experiments resembles CM in the Nojima fault (Japan) gouge in terms of Raman spectra. The granitic host rock of this fault is free of CM, and calcite is precipitated close to the CM; therefore, the CM probably formed through processes similar to those simulated in our experiments. Future research should investigate the amount and origin of CM in natural fault zones.</P>
Soichi Murakami,Kazuyuki Hirose,Yo Kurashima,Nagato Sato,Saseem Poudel,Kimitaka Tanaka,Aya Matsui,Yoshitsugu Nakanishi,Toshimichi Asano,Takehiro Noji,Yuma Ebihara,Toru Nakamura,Takahiro Tsuchikawa,Kaz 대한외상중환자외과학회 2023 Journal of Acute Care Surgery Vol.13 No.2
Purpose: General surgeons at regional hospitals should have the primary trauma care skills necessary to treat critically ill trauma patients to withstand transfer. This study was conducted to identify a consensus on primary trauma care skills for general surgeons. Methods: An initial list of acute care surgical skills was compiled, and revised by six trauma experts (acute care surgeons); 33 skills were nominated for inclusion in the Delphi consensus survey. Participants (councilors of the Japanese Society for Acute Care Surgery) were presented with the list of 33 trauma care skills and were asked (using web-based software) to rate how strongly they agreed or disagreed (using a 5-point Likert scale) with the necessity of each skill for a general surgeon. The reliability of consensus was predefined as Cronbach’s α ≥ 0.8, and trauma care skills were considered as primarily required when rated 4 (agree) or 5 (strongly agree) by ≥ 80% participants. Results: There were 117 trauma care specialists contacted to participate in the Delphi consensus survey panel. In the 1st round, 85 specialists participated (response rate: 72.6%). In the 2nd round, 66 specialists participated (response rate: 77.6%). Consensus was achieved after two rounds, reliability using Cronbach’s α was 0.94, and 34 items were identified as primary trauma care skills needed by general surgeons. Conclusion: A consensus-based list of trauma care skills required by general surgeons was developed. This list can facilitate the development of a new trauma training course which has been optimized for general surgeons.
A simplified PCR assay for fast and easy mycoplasma mastitis screening in dairy cattle
Hidetoshi Higuchi,Hidetomo Iwano,Kazuhiro Kawai,Takehiro Ohta,Tetsu Obayashi,Kazuhiko Hirose,Nobuhiko Ito,Hiroshi Yokota,Yutaka Tamura,Hajime Nagahata 대한수의학회 2011 Journal of Veterinary Science Vol.12 No.2
A simplified polymerase chain reaction (PCR) assay was developed for fast and easy screening of mycoplasma mastitis in dairy cattle. Species of major mycoplasma strains [Mycoplasma (M.) bovis, M. arginini, M. bovigenitalium, M. californicum, M. bovirhinis, M. alkalescens and M. canadense] in cultured milk samples were detected by this simplified PCR-based method as well as a standard PCR technique. The minimum concentration limit for detecting mycoplasma by the simplified PCR was estimated to be about 2.5 × 10^3 cfu/mL and was similar to that of the standard PCR. We compared the specificity and sensitivity of the simplified PCR to those of a culture method. Out of 1,685 milk samples cultured in mycoplasma broth, the simplified PCR detected Mycoplasma DNA in 152 that were also positive according to the culture assay. The sensitivity and specificity of the simplified PCR were 98.7% and 99.7%, respectively, for detecting mycoplasma in those cultures. The results obtained by the simplified PCR were consistent with ones from standard PCR. This newly developed simplified PCR, which does not require DNA purification, can analyze about 300 cultured samples within 3 h. The results from our study suggest that the simplified PCR can be used for mycoplasma mastitis screening in large-scale dairy farms.