編譯 | 李言
Nature, 22 September 2022, Volume 609 Issue 7928
《自然》2022年9月22日，第609卷，7928期
天文學Astronomy
A fast radio burst source at a complex magnetized site in a barred galaxy
一個位於棒旋星系的複雜、強磁場區域中的快速射電暴
▲ 作者：H. Xu, J. R. Niu, P. Chen, K. J. Lee et al.
▲ 連結：
https://www.nature.com/articles/s41586-022-05071-8
▲ 摘要：
快速射電暴（FRBs）是一種高度分散、持續時間為毫秒的射電暴。我們在超過一半的脈衝樣品中探測到到高圓偏振度脈衝，其中一個脈衝最高值達75%。
同時也檢測到頻率依賴的偏振振盪現象。所有這些特徵都為在大約一個天文單位的震源內存在一個複雜的、動態演變的磁化環境提供了證據。
我們發現其宿主星系是約銀河系尺度大小、富金屬的棒旋星系，同時此FRB所在區域恆星密度較低，處於旋臂之間，距離星系中心中等距離。這種環境與起源於大質量恆星極端爆炸導致的超亮超新星或伽馬射線暴後形成的年輕磁星是不一致的。
▲ Abstract：
Fast radio bursts (FRBs) are highly dispersed, millisecond-duration radio bursts. We detected circular polarization in more than half of the burst sample, including one burst reaching a high fractional circular polarization of 75%. Oscillations in fractional linear and circular polarizations, as well as polarization angle as a function of wavelength, were detected. All of these features provide evidence for a complicated, dynamically evolving, magnetized immediate environment within about an astronomical unit (AU; Earth–Sun distance) of the source. Our optical observations of its Milky-Way-sized, metal-rich host galaxy show a barred spiral, with the FRB source residing in a low-stellar-density interarm region at an intermediate galactocentric distance. This environment is inconsistent with a young magnetar engine formed during an extreme explosion of a massive star that resulted in a long gamma-ray burst or superluminous supernova.
工程學Engineering Science
Aerial additive manufacturing with multiple autonomous robots
使用多種自主機器人的空中輔助建造
▲ 作者：Ketao Zhang, Pisak Chermprayong, Feng Xiao et al.
▲ 連結：
https://www.nature.com/articles/s41586-022-04988-4
▲ 摘要：
我們提供了一個可伸縮的多機器人3D列印和路徑規劃框架，使機器人的任務和集群規模能夠適應整個建築任務中的列印需求變化。多種機器人的製造框架允許在人工監督下自主三維列印，同時實時評估列印形狀和機器行為。
為了驗證基於該框架的自主空中調幅系統，我們開發了用於在飛行過程中放置材料的建造無人機和用於評估結構質量的掃描無人機，並將通用的實時模型預測控制方案與空中調幅機器人集成在一起。
此外，我們將動態自調機械手與建造無人機集成在一起，進一步將製造精度提高到5毫米，以滿足精確軌跡要求的列印幾何圖形，並開發了四種適合連續材料沉積的水泥-聚合物複合混合物。
在此，我們演示了概念列印，包括一個由72層快速固化的絕緣泡沫材料組成的2.05米高圓柱體，一個由28層結構偽塑料膠結材料組成的0.18米高圓柱體，一個圓頂形狀的光跡虛擬列印以及多機器人模擬情況。空中輔助建造（Aerial-AM）允許在空中進行製造，為未來在危險區、高空或難以到達的位置建造提供了可能性。
▲ Abstract：
We present a scalable multi-robot three-dimensional (3D) printing and path-planning framework that enables robot tasks and population size to be adapted to variations in print geometry throughout a building mission. The multi-robot manufacturing framework allows for autonomous three-dimensional printing under human supervision, real-time assessment of printed geometry and robot behavioural adaptation. To validate autonomous Aerial-AM based on the framework, we develop BuilDrones for depositing materials during flight and ScanDrones for measuring the print quality, and integrate a generic real-time model-predictive-control scheme with the Aerial-AM robots. In addition, we integrate a dynamically self-aligning delta manipulator with the BuilDrone to further improve the manufacturing accuracy to five millimetres for printing geometry with precise trajectory requirements, and develop four cementitious–polymeric composite mixtures suitable for continuous material deposition. We demonstrate proof-of-concept prints including a cylinder 2.05 metres high consisting of 72 layers of a rapid-curing insulation foam material and a cylinder 0.18 metres high consisting of 28 layers of structural pseudoplastic cementitious material, a light-trail virtual print of a dome-like geometry, and multi-robot simulations. Aerial-AM allows manufacturing in-flight and offers future possibilities for building in unbounded, at-height or hard-to-access locations.
化學Chemistry
Electroreduction of nitrogen with almost 100% current-to-ammonia efficiency
近乎100%電流-氨效率的氨生成
▲ 作者：Hoang-Long Du, Manjunath Chatti, Rebecca Y. Hodgetts et al.
▲ 連結：
https://www.nature.com/articles/s41586-022-05108-y
▲ 摘要：
在此，我們研究了電解質在電化學鋰介導的氮還原反應中的作用，並提出了一個在電極-電解質界面區域的緊密離子層可行的高效、穩健的合成方式。該界面由高濃度的亞胺基鋰鹽電解質產生，提供穩定的氨產率150 ± 20 nmol s−1 cm−2，電流-氨效率接近100%。
在電極表面形成的離子組合抑制了電解質的分解，並支持穩定的氮還原。我們的研究強調了鋰介導的氮還原反應的性能與電極-電解質界面的物理化學性質之間的相互關係。我們預計，這些發現將指導可持續的穩健、高性能的氨合成開發。
▲ Abstract：
Here we investigate the role of the electrolyte in this reaction and present a high-efficiency, robust process that is enabled by compact ionic layering in the electrode–electrolyte interface region. The interface is generated by a high-concentration imide-based lithium-salt electrolyte, providing stabilized ammonia yield rates of 150 ± 20 nmol s−1cm−2 and a current-to-ammonia efficiency that is close to 100%. The ionic assembly formed at the electrode surface suppresses the electrolyte decomposition and supports stable N2 reduction. Our study highlights the interrelation between the performance of the lithium-mediated nitrogen-reduction reaction and the physicochemical properties of the electrode–electrolyte interface. We anticipate that these findings will guide the development of a robust, high-performance process for sustainable ammonia production.
地球科學Earth science
Diverse tsunamigenesis triggered by the Hunga Tonga-Hunga Ha』apai eruption
湯加洪阿哈阿帕伊島火山爆發引發的多種海嘯成因
▲ 作者：Patrick Lynett, Maile McCann, Zili Zhou et al.
▲ 連結：
https://www.nature.com/articles/s41586-022-05170-6
▲ 摘要：
在此，我們爆炸噴發通過多種機制產生的波，包括：（1）在火山爆發的附近，空氣-海洋與最初的和從爆炸中輻射出來的強大衝擊波；（2）水下噴發造成的水腔塌陷；（3）空氣-海洋與環繞地球幾圈的氣壓脈衝耦合，導致全球海嘯。
近場海嘯的影響受水腔源的強烈控制，遠場海嘯異常持久，主要由於氣壓脈衝機制。幾十厘米的幅度也能導致遙遠地區港口的災難性破壞，這意味著海平面適度上升加上未來類似的事件，對基礎設施的影響呈階梯函數增長。
將此類事件的複雜情況拼湊起來，對類似地球物理環境下的沿海災害評估有重要影響，表明了這是一種目前被忽視的全球海嘯來源。
▲ Abstract：
Here we show that the explosive eruption generated waves through multiple mechanisms, including: (1) air–sea coupling with the initial and powerful shock wave radiating out from the explosion in the immediate vicinity of the eruption; (2) collapse of the water cavity created by the underwater explosion; and (3) air–sea coupling with the air-pressure pulse that circled the Earth several times, leading to a global tsunami. In the near field, tsunami impacts are strongly controlled by the water-cavity source whereas the far-field tsunami, which was unusually persistent, can be largely described by the air-pressure pulse mechanism. Catastrophic damage in some harbours in the far field was averted by just tens of centimetres, implying that a modest sea level rise combined with a future, similar event would lead to a step-function increase in impacts on infrastructure. Piecing together the complexity of this event has broad implications for coastal hazards in similar geophysical settings, suggesting a currently neglected source of global tsunamis.
Global Tonga tsunami explained by a fast-moving atmospheric source
快速移動的大氣源解釋了湯加火山引發的全球海嘯
▲ 作者：R. Omira, R. S. Ramalho, J. Kim, P. J. González et al.
▲ 連結：
https://www.nature.com/articles/s41586-022-04926-4
▲ 摘要：
在此，我們使用來自全球的海平面、大氣和衛星數據，以及數值和分析模型，以證明這場海嘯是被一個不斷移動的氣源所驅動的。
在這個氣源中，火山噴發造成的聲-重力波激發了海洋，並通過共振的方式將能量轉移到海洋中。海嘯和聲-重力波到達時間之間的直接關聯證實了這些現象是密切相關的。
我們的模型還表明，海嘯異常快速的到達時間和漫長的持續時間，以及它的全球範圍，與空氣-水耦合源一致。這種耦合機制具有明顯的危險含義，因為它會導致從深水海域上升的陸地上的海浪更高。
▲ Abstract：
Here we use sea-level, atmospheric and satellite data from across the globe, along with numerical and analytical models, to demonstrate that this tsunami was driven by a constantly moving source in which the acoustic-gravity waves radiating from the eruption excite the ocean and transfer energy into it by means of resonance. A direct correlation between the tsunami and the acoustic-gravity waves』 arrival times confirms that these phenomena are closely linked. Our models also show that the unusually fast travel times and long duration of the tsunami, as well as its global reach, are consistent with an air–water-coupled source. This coupling mechanism has clear hazard implications, as it leads to higher waves along land masses that rise abruptly from long stretches of deep ocean waters.
Surface-to-space atmospheric waves from Hunga Tonga–Hunga Ha』apai eruption
湯加洪阿哈阿帕伊島火山爆發導致的地-空大氣波
▲ 作者：Corwin J. Wright, Neil P. Hindley, M. Joan Alexander et al.
▲ 連結：
https://www.nature.com/articles/s41586-022-05012-5
▲ 摘要：
在此，我們使用了一套全面的衛星和地面觀測，從地面到電離層對其進行量化，展示湯加火山爆發導致的全球範圍波響應的細節。
初始爆炸引發了廣譜波，其中蘭姆波在地表的傳播速度為318.2±6 m s−1，在平流層的傳播速度為308±5 ~ 319±4 m s−1，重力波在平流層的傳播速度為238±3 ~ 269±3 m s−1。
此前從未觀測到在電離層以下高度的引力波以這種速度傳播，或從單一來源傳播到整個地球。在超過12小時的時間裡，羽流釋放的潛熱仍然是世界範圍內最重要的單個重力波源，在衛星觀測中產生了橫跨太平洋盆地的圓形波面。
在觀測記錄中，單一源支配如此大的區域也是獨一無二的。湯加火山爆發在研究大氣如何對突然的點源驅動狀態變化作出反應中成為了一個重要的自然實驗，將有助於改進天氣和氣候模型。
▲ Abstract：
Here we show the details of this response, using a comprehensive set of satellite and ground-based observations to quantify it from surface to ionosphere. A broad spectrum of waves was triggered by the initial explosion, including Lamb waves propagating at phase speeds of 318.2 ± 6 m s−1 at surface level and between 308 ± 5 to 319 ± 4 m s−1 in the stratosphere, and gravity waves propagating at 238 ± 3 to 269 ± 3 m s−1 in the stratosphere. Gravity waves at sub-ionospheric heights have not previously been observed propagating at this speed or over the whole Earth from a single source. Latent heat release from the plume remained the most significant individual gravity wave source worldwide for more than 12 h, producing circular wavefronts visible across the Pacific basin in satellite observations. A single source dominating such a large region is also unique in the observational record. The Hunga Tonga eruption represents a key natural experiment in how the atmosphere responds to a sudden point-source-driven state change, which will be of use for improving weather and climate models.