Deep-sea record of impact apparently unrelated to mass extinction in the Late Triassic

Onoue, Tetsuji*; Sato, Honami*; Nakamura, Tomoki*; Noguchi, Takaaki*; Hidaka, Yoshihiro*; Shirai, Naoki*; Ebihara, Mitsuru*; Osawa, Takahito; Hatsukawa, Yuichi; Toh, Yosuke; et al.

Proceedings of the National Academy of Sciences of the United States of America, 109(47), p.19134 - 19139, 2012/11

https://doi.org/10.1073/pnas.1209486109

The 34 million year (My) interval of the Late Triassic is marked by the formation of several large impact structures on Earth. As with the Chicxulub impact event at the Cretaceous/Paleogene boudary, the Late Triassic impact events have been considered a factor in biotic extinction events in the Late Triassic (e.g., the Triassic/Jurassic boundary). However, the causal link between these impact events and a mass extinction event in the Late Triassic remains controversial because of a lack of stratigraphic records of their ejecta deposits. Here we report evidence for an impact event (platinum group elements anomaly, nickel-rich magnetite and microspherules) deposited within a Paleo-Pacific basin in the middle Norian (Upper Triassic) deep-sea sediment in Japan. This includes anomalously high abundances of iridium, up to 41.5 parts per billion (ppb), in the ejecta deposit, which suggests that the iridium anomaly may be found on a global scale. The middle Norian age of the ejecta deposit suggests that the impact event that produced the 100-km-wide Manicouagan crater in Canada8 is most likely related to its deposition. Our analysis of siliceous microfossils shows no evidence of a mass extinction event across the impact event horizon, and no contemporaneous faunal turnover is seen in other marine fossils. However, such an event has been reported among terrestrial tetrapods and floras in North America. We therefore hypothesize that the Manicouagan impact caused the catastrophic collapse of terrestrial ecosystems near the impact site, but not within the marine realm.

Small-sized human immunodeficiency virus type-1 protease inhibitors containing allophenylnorstatine to explore the S2' pocket

Hidaka, Koshi*; Kimura, Toru*; Abdel-Rahman, H. M.*; Nguyen, J.-T.*; McDaniel, K. F.*; Kohlbrenner, W. E.*; Molla, A.*; Adachi, Motoyasu; Tamada, Taro; Kuroki, Ryota; et al.

Journal of Medicinal Chemistry, 52(23), p.7604 - 7617, 2009/07

https://doi.org/10.1021/jm9005115

A series of HIV protease inhibitor based on the allophenylnorstatine structure with various P2' moieties were synthesized. Among these analogues, we discovered that a small allyl group would maintain potent enzyme inhibitory activity compared to that of the -methylbenzyl moiety in clinical candidate 1 (KNI-764, also known as JE-2147, AG-1776 or SM-319777). Introduction of an anilinic amino group to 2 (KNI-727) improved water-solubility and anti-HIV-1 activity. X-ray crystallographic analysis of 13k (KNI-1689) with a -methallyl group at P2' position revealed hydrophobic interactions with Ala28, Ile84, and Ile50' similar to that of 1. The presence of an additional methyl group on the allyl group in compound 13k significantly increased anti-HIV activity over 1, while providing a rational drug design for structural minimization and improving membrane permeability.

International Standard Problem (ISP) No.41; Containment iodine computer code exercise based on a Radionuclide Test Facility (RTF) experiment

Wren, J. C.*; Royen, J.*; Ball, J.*; Glowa, G.*; Rydl, A.*; Poletiko, C.*; Billarand, Y.*; Ewig, F.*; Funke, F.*; Zeh, P.*; et al.

NEA/CSNI/R(2000)6/Vol.1, Vol.2, 174 Pages, 2000/04

Imaging plate neutron detector

Niimura, Nobuo*; *; *; *; *; *; ; Hidaka, M.*

Nuclear Instruments and Methods in Physics Research A, 349, p.521 - 525, 1994/00

https://doi.org/10.1016/0168-9002(94)91220-3

no abstracts in English