Science News | June 24(1), 2008

# 何だか異様に疲れが溜まる一方な今日この頃…

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Biotechnology Japan | 記者発表、産業技術総合研究所、高純度半導体カーボンナノチューブを用いた高性能トランジスタを作製

産総研：プレス・リリース　高純度半導体カーボンナノチューブを用いた高性能トランジスタを作製

Semiconductor-enriched single wall carbon nanotube networks applied to field effect transistors.
N. Izard, S. Kazaoui, K. Hata, T. Okazaki, T. Saito, S. Iijima, N. Minami.
Appl. Phys. Lett. 92, 243112 (2008) | DOI:10.1063/1.2939560

Substantial progress on field effect transistors (FETs) consisting of semiconducting single wall carbon nanotubes (s-SWNTs) without detectable traces of metallic nanotubes and impurities is reported. Nearly perfect removal of metallic nanotubes is confirmed by optical absorption, Raman measurements, and electrical measurements. This outstanding result was made possible in particular by ultracentrifugation (150  000  g) of solutions prepared from SWNT powders using polyfluorene as an extracting agent in toluene. Such s-SWNTs processable solutions were applied to realize FET, embodying randomly or preferentially oriented nanotube networks prepared by spin coating or dielectrophoresis. Devices exhibit stable p-type semiconductor behavior in air with very promising characteristics. The on-off current ratio is 10⁵, the on-current level is around 10  µA, and the estimated hole mobility is larger than 2  cm²/V  s.

　# やっと見つけた…
　# カーボンナノチューブがどんどん実用化に向けて進んでいく…

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過剰な恐怖の「ブレーキ役」解明　群馬大がマウス実験 - MSN産経ニュース

恐怖記憶：ブレーキかけるたんぱく質を特定　群馬大チーム - 毎日ｊｐ(毎日新聞)

Inducible cAMP Early Repressor Acts as a Negative Regulator for Kindling Epileptogenesis and Long-Term Fear Memory.
Nobuhiko Kojima, Gilyana Borlikova, Toshiro Sakamoto, Kazuyuki Yamada, Toshio Ikeda, Shigeyoshi Itohara, Hiroaki Niki, Shogo Endo.
The Journal of Neuroscience 28, 6459-6472 (2008) | doi:10.1523/JNEUROSCI.0412-08.2008

Long-lasting neuronal plasticity as well as long-term memory (LTM) requires de novo synthesis of proteins through dynamic regulation of gene expression. cAMP-responsive element (CRE)-mediated gene transcription occurs in an activity-dependent manner and plays a pivotal role in neuronal plasticity and LTM in a variety of species. To study the physiological role of inducible cAMP early repressor (ICER), a CRE-mediated gene transcription repressor, in neuronal plasticity and LTM, we generated two types of ICER mutant mice: ICER-overexpressing (OE) mice and ICER-specific knock-out (KO) mice. Both ICER-OE and ICER-KO mice show no apparent abnormalities in their development and reproduction. A comprehensive battery of behavioral tests revealed no robust changes in locomotor activity, sensory and motor functions, and emotional responses in the mutant mice. However, long-term conditioned fear memory was attenuated in ICER-OE mice and enhanced in ICER-KO mice without concurrent changes in short-term fear memory. Furthermore, ICER-OE mice exhibited retardation of kindling development, whereas ICER-KO mice exhibited acceleration of kindling. These results strongly suggest that ICER negatively regulates the neuronal processes required for long-term fear memory and neuronal plasticity underlying kindling epileptogenesis, possibly through suppression of CRE-mediated gene transcription.

　# 「米神経科学誌」って、どれだけあると思ってるんだ？…産経に至っては「米専門誌」…分かるか！
　# 「ICER」＝「inducible cAMP early repressor」だそうな
　# CREを介した遺伝子発現調節因子は他にないのかな？

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2008年6月18日「水深10,350メートルの海底下堆積物採取」　サイエンスポータル編集ニュース　科学技術 全て伝えます サイエンスポータル / SciencePortal

大深度小型無人探査機「ABISMO」が世界で初めてマリアナ海溝水深1万m超の海洋～海底面～海底下の連続的試料採取に成功＜プレスリリース＜JAMSTECについて＜独立行政法人海洋研究開発機構
　# 水深10,000 mの海底って、凄く興味をそそられるのは私だけ？

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Hydrogen sulphide release to surface waters at the Precambrian/Cambrian boundary.
Martin Wille, Thomas F. Nägler, Bernd Lehmann, Stefan Schröder, Jan D. Kramers.
Nature 453, 767-769 (2008) | doi:10.1038/nature07072

Animal-like multicellular fossils appeared towards the end of the Precambrian, followed by a rapid increase in the abundance and diversity of fossils during the Early Cambrian period, an event also known as the 'Cambrian explosion'. Changes in the environmental conditions at the Precambrian/Cambrian transition (about 542 Myr ago) have been suggested as a possible explanation for this event, but are still a matter of debate. Here we report molybdenum isotope signatures of black shales from two stratigraphically correlated sample sets with a depositional age of around 542 Myr. We find a transient molybdenum isotope signal immediately after the Precambrian/Cambrian transition. Using a box model of the oceanic molybdenum cycle, we find that intense upwelling of hydrogen sulphide-rich deep ocean water best explains the observed Early Cambrian molybdenum isotope signal. Our findings suggest that the Early Cambrian animal radiation may have been triggered by a major change in ocean circulation, terminating a long period during which the Proterozoic ocean was stratified, with sulphidic deep water.

　# 「カンブリア爆発」って、なんで起きたんだろうか…いや、今はどうしてそういう進化の加速が起きないんだろうか？

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asahi.com（朝日新聞社）：黄砂に乗ってカビや細菌、日本に飛来か　金沢大調査 - サイエンス
　# こちらとは別の発表…「中国・ウルムチであった国際会議で発表」だそうな…何学会やねん
　# やっぱし、黄砂は危ないって…

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5つの「スーパーアース」発見　写真3枚　国際ニュース : AFPBB News
　# 「フランス・ナント（Nantes）で行われた天文学会議」で発表だそうです
　# 地球より大きい地球型惑星って、自ずと重力も異なるから気体組成から変わってくるんじゃないかという素朴な疑問…

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asahi.com（朝日新聞社）：温暖化、１万年以上前にも　グリーンランドの氷を解析 - サイエンス

地球温暖化：最終氷期のグリーンランド、３年で気温１０度上昇 - 毎日ｊｐ(毎日新聞)

High-Resolution Greenland Ice Core Data Show Abrupt Climate Change Happens in Few Years.
J. P. Steffensen, K. K. Andersen, M. Bigler, H. B. Clausen, D. Dahl-Jensen, H. Fischer, K. Goto-Azuma, M. Hansson, S. J. Johnsen, J. Jouzel, V. Masson-Delmotte, T. Popp, S. O. Rasmussen, R. Rothlisberger, U. Ruth, B. Stauffer, M.-L. Siggaard-Andersen, A. E. Sveinbjörnsdóttir, A. Svensson, J. W. C. White.
Science, Science Express | DOI: 10.1126/science.1157707

The last two abrupt warmings at the onset of our present warm interglacial period, interrupted by the Younger Dryas cooling event, are investigated in high temporal resolution from the Greenland NGRIP ice core. The deuterium excess, a proxy of Greenland precipitation moisture source, switches mode within 1 to 3 years over these transitions and initiates a more gradual change (50 years) of the Greenland air temperature as recorded by water stable isotopes. The onsets of both abrupt Greenland warmings are slightly preceded by decreasing Greenland dust deposition, reflecting wetting of Asian deserts. A northern shift of the ITCZ could be the trigger of these abrupt shifts of northern hemisphere atmospheric circulation resulting in 2 to 4K changes in Greenland moisture source temperature from one year to the next.

　# さ、3年間で10℃上昇って凄くない？