Tephrochronological study on the 1986-1987 eruptions of Izu-Oshima volcano, Japan

Sequences and products of the Izu-Oshima 1986-1987 eruptions which started on November 15, 1986, were investigated tephrochronologically. The results are summarized as follows : 1) Summit eruptions (Crater A) During 15-20, Nov. 1986, Strombolian eruptions continued to make a lava lake from where lava flows spilt over and went down the slope of the central cone to the caldera floor (LA I～IV). Volcanic ash and scoria (TA-1～4) were dispersed to the eastern and western parts of the island. On 21 Nov., a little after the beginning of the fissure eruption (Craters B), Strombolian eruptions were reactivated and ejected large volcanic bombs and scoria (TA-5) from Crater A. On Dec. 18, 1986, small explosion occurred from the Crater A for three or four hours, ejecting a scoria fall (TA-6) and bomb. The level of the lava lake lowered about 5 meters. On Nov. 16, 1987, a phreatic explosion occurred to break the crust of the lava lake, and the lava drained back to the deep on Nov. 18. 2) Fissure eruptions in the caldera floor (Craters B) At 16 : 15, on Nov. 21, 1986, fissure eruptions (Craters B) started on the caldera floor and extended to the slope of the central cone. The eruptions became explosive one, generating lava fountains with the height of more than 1500 meters, with a high discharge rate of 8×106 ton/hour, producing pyroclastic cones and rootless (clastogenic) lava flows (LB I and III). Subplinian scoria falls were dispersed to west (TB-1) and east (TB-2). About 5 hours after the beginning, the activity waned to produce only volcanic ash (TB-3 and -6) and finer scoria falls (TB-4 and -5) and ceased on Nov. 23. A rheomorphic lava flow (LB II) occurred from the edge of the deformed cone on Nov. 23. 3) Fissure eruptions on the somma slope (Craters C) At 17 : 45, on Nov. 21, 1986, fissure eruptions occurred on the somma slope, and produced two lava flows (LC I and II), scoria cones, and vesicular scoria falls (TC-1 and -3) from the 11 craters. 4) The 1986 eruptions ejected 0.053 km3, 7.9×107 tons of lava and pyroclasts from A, B and C craters (Table 4)

Cold start cycling durability of fuel cell stacks for commercial automotive applications

System durability is crucial for the successful commercialization of polymer electrolyte fuel cells (PEFCs) in fuel cell electric vehicles (FCEVs). Besides conventional electrochemical cycling durability during long-term operation, the effect of operation in cold climates must also be considered. Ice formation during start up in sub-zero conditions may result in damage to the electrocatalyst layer and the polymer electrolyte membrane (PEM). Here, we conduct accelerated cold start cycling tests on prototype fuel cell stacks intended for incorporation into commercial FCEVs. The effect of this on the stack performance is evaluated, the resulting mechanical damage is investigated, and degradation mechanisms are proposed. Overall, only a small voltage drop is observed after the durability tests, only minor damage occurs in the electrocatalyst layer, and no increase in gas crossover is observed. This indicates that these prototype fuel cell stacks successfully meet the cold start durability targets for automotive applications in FCEVs

Accelerated durability testing of fuel cell stacks for commercial automotive applications : a case study

System durability is crucially important for the successful commercialization of fuel cell electric vehicles (FCEVs). Conventional accelerated durability testing protocols employ relatively high voltage to hasten carbon corrosion and/or platinum catalyst degradation. However, high voltages are strictly avoided in commercialized FCEVs such as the Toyota MIRAI to minimize these degradation modes. As such, conventional durability tests are not representative of real-world FCEV driving conditions. Here, modified start-stop and load cycle durability tests are conducted on prototype fuel cell stacks intended for incorporation into commercial FCEVs. Polarization curves are evaluated at beginning of test (BOT) and end of test (EOT), and the degradation mechanisms are elucidated by separating the overvoltages at both 0.2 and 2.2 A cm-2. Using our modified durability protocols with a maximum cell voltage of 0.9 V, the prototype fuel cell stacks easily meet durability targets for automotive applications, corresponding to 15-year operation and 200,000 km driving range. These findings have been applied successfully in the development of new fuel cell systems for FCEVs, in particular the second-generation Toyota MIRAI

タンキ コウカン リュウガク プログラム ニ オケル チイキ レンケイガタ PBL ノ ジッセン ト カダイ

大阪大学日本語日本文化教育センターの短期交換留学生プログラムであるメイプル・プログラムでは、「ほかの文化の人たちや社会とつながることができる」人材の育成を目的とし、地域の市民団体、近隣の企業、大阪大学内の他部局との連携のもと、居住地域の課題を発見して、その解決に向けて何をするべきかを考える未来志向のPBLを取り入れた授業を行っている。本稿は2020年度春～夏学期のPBLの実践における成果と課題の報告である。留学生、および発表会に参加したゲストへの事後アンケート調査の結果、留学生たちが主体性や積極性をもってPBL活動に取り組んだこと、市民団体の方々や他部局の教員と日本語で関わる機会を設けられたこと、留学生が地域社会に深い関心を持ったこと等が大きな成果であるとわかった。一方、当事者意識をもって課題の解決方法を探すという点で課題が残り、今後、「探究から学ぶ」「他者から学ぶ」「過去から学ぶ」といった学ぶ姿勢の構築という面での改善が求められる

タンキ コウカン リュウガク プログラム ニ オケル サンガクミン レンケイガタ セミナー カイサイ ノ イギ ト カダイ

大阪大学短期交換留学プログラムの一つであるメイプル・プログラムでは、コロナ禍で渡日できていない留学生が地域住民から地域に密着した情報を得ることにより、留学先である箕面市についてのイメージを喚起することを目的として、産学民連携型のセミナー「Let me know! Minoh! セミナー」を開催した。このセミナーは、のちのPBL（Project-based Learning）活動へとつなげるものである。本セミナーは「主体」「場」「方法」という３つの新しさを兼備したものであった。セミナー開催後に参加学生を対象に行ったアンケートの結果、箕面市の情報の獲得、箕面市への興味の高まりおよびイメージ喚起、箕面市民との関係性構築への期待の高まりなどの成果が顕著であった。また実際に、後日行ったPBL発表会における発表タイトルでは、箕面市に関する幅広いテーマに取り組んでいるグループが複数見られた。以上のようなことから、本セミナーを行ったことにより、学生に箕面市の一員であるという自覚が芽生え、PBL発表会に取り組めたことが明らかになった

DOCK2 is involved in the host genetics and biology of severe COVID-19

「コロナ制圧タスクフォース」COVID-19疾患感受性遺伝子DOCK2の重症化機序を解明 --アジア最大のバイオレポジトリーでCOVID-19の治療標的を発見--. 京都大学プレスリリース. 2022-08-10.Identifying the host genetic factors underlying severe COVID-19 is an emerging challenge. Here we conducted a genome-wide association study (GWAS) involving 2, 393 cases of COVID-19 in a cohort of Japanese individuals collected during the initial waves of the pandemic, with 3, 289 unaffected controls. We identified a variant on chromosome 5 at 5q35 (rs60200309-A), close to the dedicator of cytokinesis 2 gene (DOCK2), which was associated with severe COVID-19 in patients less than 65 years of age. This risk allele was prevalent in East Asian individuals but rare in Europeans, highlighting the value of genome-wide association studies in non-European populations. RNA-sequencing analysis of 473 bulk peripheral blood samples identified decreased expression of DOCK2 associated with the risk allele in these younger patients. DOCK2 expression was suppressed in patients with severe cases of COVID-19. Single-cell RNA-sequencing analysis (n = 61 individuals) identified cell-type-specific downregulation of DOCK2 and a COVID-19-specific decreasing effect of the risk allele on DOCK2 expression in non-classical monocytes. Immunohistochemistry of lung specimens from patients with severe COVID-19 pneumonia showed suppressed DOCK2 expression. Moreover, inhibition of DOCK2 function with CPYPP increased the severity of pneumonia in a Syrian hamster model of SARS-CoV-2 infection, characterized by weight loss, lung oedema, enhanced viral loads, impaired macrophage recruitment and dysregulated type I interferon responses. We conclude that DOCK2 has an important role in the host immune response to SARS-CoV-2 infection and the development of severe COVID-19, and could be further explored as a potential biomarker and/or therapeutic target

Wide-area Group Communication Protocols- International Experiment

In distributed applications, a group of multiple processes is required to be cooperated by exchanging multimedia data. In addition, world-wide distributed applications are being realized by using the Internet. The traditional group communication protocols assume that every pair of processes support almost the same and fixed delay time and reliability level. In world-wide multimedia applications, the assumption does not hold. We discuss high-speed protocols which can change the ways for distributing messages to multiple destinations and retransmitting messages to processes losing the messages in the wide-area group in the change of the delay and reliability. 1