科研
科研
编译|李言
Nature, 29 August 2024, Volume 632 Issue 8027
《自然》2024年8月29日，第632卷，8027期
地球科学Earth Science
Earth’s ambipolar electrostatic field and its role in ion escape to space
地球的双极静电场及其在离子逃逸到太空中扮演的角色
▲ 作者：Glyn A. Collinson, Alex Glocer et al.
▲ 链接：https://www.nature.com/articles/s41586-024-07480-3
▲摘要：
在此，我们报告在250千米至768千米范围内，仅由电离层电子向外压力产生的行星静电场（E∥⊕=1.09±0.17μVm?1）存在+0.55±0.09V的电位降。我们的实验表明，地球的双极静电场控制着极地电离层的结构，将范围高度提升至271%。
我们认为这将使冷O+离子向磁层的供应增加了3800%以上，其中波粒相互作用等其他机制可以加热并进一步加速它们达到逃逸速度。地球的静电场足够强大到驱动极地风，并且可能是主导大部分磁层的冷氢离子群的起源。
▲ Abstract：
Here we report the existence of a +0.55?±?0.09?V electric potential drop between 250?km and 768?km from a planetary electrostatic field (E∥⊕?=?1.09?±?0.17?μV?m?1) generated exclusively by the outward pressure of ionospheric electrons. We experimentally demonstrate that the ambipolar field of Earth controls the structure of the polar ionosphere, boosting the scale height by 271%. We infer that this increases the supply of cold O+ ions to the magnetosphere by more than 3,800%, in which other mechanisms such as wave–particle interactions can heat and further accelerate them to escape velocity. The electrostatic field of Earth is strong enough by itself to drive the polar wind and is probably the origin of the cold H+ ion population1 that dominates much of the magnetosphere.
天文学Astronomy
A nebular origin for the persistent radio emission of fast radio bursts
快速射电暴持续射电发射的星云起源
▲ 作者：Gabriele Bruni, Luigi Piro et al.
▲ 链接：https://www.nature.com/articles/s41586-024-07782-6
▲ 摘要：
在此，我们报告在距离413Mpc的重复快速射电暴源FRB20201124A相关的第三个亮度较低的持续射电源的检测，这大大扩展了预测关系到低亮度—低法拉第旋转测量范围（<1000?rad?m?2）。
在较低的法拉第旋转测量值下，预期的射电光度低于当今射电望远镜的探测极限。这些发现支持了这样一种观点，即到目前为止观测到的持续射电源是由快速射电暴环境中的星云产生的，并且由于较弱的磁离子介质，具有低法拉第旋转测量的快速射电暴可能不会显示出持续射电源。
这与将年轻的磁星作为快速射电暴中心引擎的模型基本一致。在该模型中，周围的电离星云或双星系统中的相互作用激波为持续的射电源提供动力。
▲ Abstract：
Here we report the detection of a third, less luminous persistent radio source associated with the repeating FRB source FRB?20201124A at a distance of 413?Mpc, substantially expanding the predicted relation into the low luminosity–low Faraday rotation measure regime (<1,000?rad?m?2). At lower values of the Faraday rotation measure, the expected radio luminosity falls below the limit-of-detection threshold for present-day radio telescopes. These findings support the idea that the persistent radio sources observed so far are generated by a nebula in the FRB environment and that FRBs with low Faraday rotation measure may not show a persistent radio source because of a weaker magneto-ionic medium. This is generally consistent with models invoking a young magnetar as the central engine of the FRB, in which the surrounding ionized nebula—or the interacting shock in a binary system—powers the persistent radio source.
工程学Engineering
Passive wing deployment and retraction in beetles and flapping microrobots
甲虫和扑翼微型机器人翅膀的被动展开和收拢
▲ 作者：Hoang-Vu Phan, Hoon Cheol Park & Dario Floreano
▲ 链接：https://www.nature.com/articles/s41586-024-07755-9
▲摘要：
在此，我们展示了犀金龟可以毫不费力地展开它们的后翅，而不需要肌肉活动。我们展示了打开鞘翅会将像弹簧一样的后翅部分从身体上释放出来，从而为随后的拍打动作提供所需的空间，从而使后翅进入飞行位置。
飞行结束后，犀金龟可以利用鞘翅推动后翅回到静止位置，进一步支持了被动展开的假设。我们用一个能被动展开翅膀进行稳定可控飞行、并在着陆时整齐地收回翅膀的扑翼微型机器人验证了这一假设，展示了一种简单而有效的设计类昆虫飞行微型机器的方法。
▲ Abstract：
Here we demonstrate that rhinoceros beetles can effortlessly deploy their hindwings without necessitating muscular activity. We show that opening the elytra triggers a spring-like partial release of the hindwings from the body, allowing the clearance needed for the subsequent flapping motion that brings the hindwings into the flight position. After flight, the beetle can use the elytra to push the hindwings back into the resting position, further strengthening the hypothesis of passive deployment. We validated the hypothesis using a flapping microrobot that passively deployed its wings for stable, controlled flight and retracted them neatly upon landing, demonstrating a simple, yet effective, approach to the design of insect-like flying micromachines.
化学Chemistry
Methyl-reducing methanogenesis by a thermophilic culture of Korarchaeia
高丽菌嗜热培养的甲基还原甲烷生成
▲ 作者：Viola Krukenberg, Anthony J. Kohtz, Zackary J. Jay & Roland Hatzenpichler
▲ 链接：https://www.nature.com/articles/s41586-024-07829-8
▲ 摘要：
在此，我们展示了热变形门（TACK超门）中Korarchaeia谱系成员的产甲烷生长。通过对washburnenis候选甲烷脱硫菌LCB3的富集培养，我们对代谢活性和同位素示踪剂转化进行了测量，以证明以氢为电子供体的甲醇还原为甲烷。
对古菌环基因组和转录组的分析揭示了与甲烷生成相关的能量守恒途径的独特修饰，包括参与氢和硫代谢的酶复合物。这一新的古细菌群的培养和鉴定对于更深入地评估产甲烷菌的多样性、生理和生物化学至关重要。
▲ Abstract：
Here we show methanogenic growth by a member of the lineage Korarchaeia within the phylum Thermoproteota (TACK superphylum). Following enrichment cultivation of ‘Candidatus Methanodesulfokora washburnenis’ strain LCB3, we used measurements of metabolic activity and isotope tracer conversion to demonstrate methanol reduction to methane using hydrogen as an electron donor. Analysis of the archaeon’s circular genome and transcriptome revealed unique modifications in the energy conservation pathways linked to methanogenesis, including enzyme complexes involved in hydrogen and sulfur metabolism. The cultivation and characterization of this new group of archaea is critical for a deeper evaluation of the diversity, physiology and biochemistry of methanogens.
生物学Biology
The Space Omics and Medical Atlas (SOMA) and international astronaut biobank
空间组学和医学图谱（SOMA）与国际宇航员生物库
▲ 作者：Eliah G. Overbey, JangKeun Kim et al.
▲ 链接：https://www.nature.com/articles/s41586-024-07639-y
▲ 摘要：
在此，我们介绍了空间组学和医学图谱（SOMA）。这是一个集成的数据和样本存储库，包含来自不同任务的临床、细胞和多组学研究资料，包括NASA双胞胎研究、JAXA CFE研究、SpaceX灵感4号机组以及Axiom和Polaris。SOMA资源代表了公开可用的人类空间组学数据增加了10倍以上，康奈尔航空航天医学生物库提供了匹配的样本。
该图谱包括广泛的分子和生理图谱，包括基因组学、表观基因组学、转录组学、蛋白质组学、代谢组学和微生物组数据集，揭示了跨任务的一些一致特征，包括细胞因子转移、端粒延伸和基因表达变化，以及任务特异性分子反应和与同源、组织特异性小鼠数据集的链接。
▲ Abstract：
Here we present the Space Omics and Medical Atlas (SOMA), an integrated data and sample repository for clinical, cellular and multi-omic research profiles from a diverse range of missions, including the NASA Twins Study, JAXA CFE study, SpaceX Inspiration4 crew, Axiom and Polaris. The SOMA resource represents a more than tenfold increase in publicly available human space omics data, with matched samples available from the Cornell Aerospace Medicine Biobank. The Atlas includes extensive molecular and physiological profiles encompassing genomics, epigenomics, transcriptomics, proteomics, metabolomics and microbiome datasets, which reveal some consistent features across missions, including cytokine shifts, telomere elongation and gene expression changes, as well as mission-specific molecular responses and links to orthologous, tissue-specific mouse datasets.
Molecular and physiological changes in the SpaceX Inspiration4 civilian crewSpaceX Inspiration4
民用机组人员的分子和生理变化
▲ 作者：Christopher W. Jones, Eliah G. Overbey et al.
▲ 链接：https://www.nature.com/articles/s41586-024-07648-x
▲摘要：
在此，我们报告了针对为期3天太空飞行任务的主要发现。该任务引起了广泛的生理和应激反应、以眼球错位为指标的神经前庭变化，以及神经认知功能的改变，其中一些与长期太空飞行相匹配，但几乎所有这些与返回地球后的基线（飞行前）没有差异。
总体而言，这些初步民用航天数据表明，短期飞行任务不会造成重大健康风险，而且在解剖、细胞、生理和认知水平上测量人体对航天的最早适应阶段提供了丰富的机会。最后，这些方法和结果为建立一个开放的、快速扩展的宇航员生物医学数据库奠定了基础，该数据库可以为私人和政府资助的太空任务提供对策开发信息。
▲ Abstract：
Here we report the primary findings from the 3-day spaceflight mission, which induced a broad range of physiological and stress responses, neurovestibular changes indexed by ocular misalignment, and altered neurocognitive functioning, some of which match those of long-term spaceflight, but almost all of which did not differ from baseline (pre-flight) after return to Earth. Overall, these preliminary civilian spaceflight data suggest that short-duration missions do not pose a significant health risk, and moreover present a rich opportunity to measure the earliest phases of adaptation to spaceflight in the human body at anatomical, cellular, physiological and cognitive levels. Finally, these methods and results lay the foundation for an open, rapidly expanding biomedical database for astronauts, which can inform countermeasure development for both private and government-sponsored space missions.
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