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Reversible stickiness is something to smile about 新闻
来源平台：EurekAlert. 发布日期：2020
作者:  admin
收藏  |  浏览/下载：2/0  |  提交时间：2020/12/07
The applications of liquid crystals have been extended to drug encapsulation 新闻
来源平台：EurekAlert. 发布日期：2020
作者:  admin
收藏  |  浏览/下载：0/0  |  提交时间：2020/11/09
Fleet of robotic probes will monitor global warming’s impact on microscopic ocean life 新闻
来源平台：Science. 发布日期：2020
作者:  admin
收藏  |  浏览/下载：1/0  |  提交时间：2020/11/05
Nose's response to odors more than just a simple sum of parts 新闻
来源平台：EurekAlert. 发布日期：2020
作者:  admin
收藏  |  浏览/下载：2/0  |  提交时间：2020/09/22
Do you ever wonder what might be in your drinking water? 新闻
来源平台：Cary Institute of Ecosystem Studies. 发布日期：2020
作者:  admin
收藏  |  浏览/下载：38/0  |  提交时间：2020/08/24
Sustainable agriculture explained! 新闻
来源平台：International Union for Conservation of Nature. 发布日期：2020
作者:  admin
收藏  |  浏览/下载：4/0  |  提交时间：2020/07/01
Ethnolinguistic diversity slows down urban growth 新闻
来源平台：EurekAlert. 发布日期：2020
作者:  admin
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The Lancet Infectious Diseases: Study from Chinese city of Guangzhou provides key insights on how COVID-19 spreads in households 新闻
来源平台：EurekAlert. 发布日期：2020
作者:  admin
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Modeling the Future of COVID-19: Q&A with RAND Experts 新闻
来源平台：RAND Corporation. 发布日期：2020
作者:  admin
收藏  |  浏览/下载：1/0  |  提交时间：2020/06/03
Hydrothermal (NN)-N-15-N-15 abundances constrain the origins of mantle nitrogen 期刊论文
NATURE, 2020, 580 (7803) : 367-+
作者:  Zhao, Steven;  Jang, Cholsoon;  Liu, Joyce;  Uehara, Kahealani;  Gilbert, Michael;  Izzo, Luke;  Zeng, Xianfeng;  Trefely, Sophie;  Fernandez, Sully;  Carrer, Alessandro;  Miller, Katelyn D.;  Schug, Zachary T.;  Snyder, Nathaniel W.;  Gade, Terence P.;  Titchenell, Paul M.;  Rabinowitz, Joshua D.;  Wellen, Kathryn E.
收藏  |  浏览/下载：14/0  |  提交时间：2020/05/13

Nitrogen is the main constituent of the Earth'  s atmosphere, but its provenance in the Earth'  s mantle remains uncertain. The relative contribution of primordial nitrogen inherited during the Earth'  s accretion versus that subducted from the Earth'  s surface is unclear(1-6). Here we show that the mantle may have retained remnants of such primordial nitrogen. We use the rare (NN)-N-15-N-15 isotopologue of N-2 as a new tracer of air contamination in volcanic gas effusions. By constraining air contamination in gases from Iceland, Eifel (Germany) and Yellowstone (USA), we derive estimates of mantle delta N-15 (the fractional difference in N-15/N-14 from air), N-2/Ar-36 and N-2/He-3. Our results show that negative delta N-15 values observed in gases, previously regarded as indicating a mantle origin for nitrogen(7-10), in fact represent dominantly air-derived N-2 that experienced N-15/N-14 fractionation in hydrothermal systems. Using two-component mixing models to correct for this effect, the (NN)-N-15-N-15 data allow extrapolations that characterize mantle endmember delta N-15, N-2/Ar-36 and N-2/He-3 values. We show that the Eifel region has slightly increased delta N-15 and N-2/Ar-36 values relative to estimates for the convective mantle provided by mid-ocean-ridge basalts(11), consistent with subducted nitrogen being added to the mantle source. In contrast, we find that whereas the Yellowstone plume has delta N-15 values substantially greater than that of the convective mantle, resembling surface components(12-15), its N-2/Ar-36 and N-2/He-3 ratios are indistinguishable from those of the convective mantle. This observation raises the possibility that the plume hosts a primordial component. We provide a test of the subduction hypothesis with a two-box model, describing the evolution of mantle and surface nitrogen through geological time. We show that the effect of subduction on the deep nitrogen cycle may be less important than has been suggested by previous investigations. We propose instead that high mid-ocean-ridge basalt and plume delta N-15 values may both be dominantly primordial features.