自然（20220922出版）一周论文导读

　　编译 | 李言
　　Nature , 22 September 2022, Volume 609 Issue 7928
　　《自然》 2022年9月22日，第609卷，7928期
　　天文学 Astronomy
　　A fast radio burst source at a complex magnetized site in a barred galaxy
　　一个位于棒旋星系的复杂、强磁场区域中的快速射电暴
　　▲ 作者：H. Xu, J. R. Niu, P. Chen, K. J. Lee et al.
　　▲ 链接：
　　https://www.nature.com/articles/s41586-022-05071-8
　　▲ 摘要：
　　快速射电暴（FRBs）是一种高度分散、持续时间为毫秒的射电暴。我们在超过一半的脉冲样品中探测到到高圆偏振度脉冲，其中一个脉冲最高值达75%。
　　同时也检测到频率依赖的偏振振荡现象。所有这些特征都为在大约一个天文单位的震源内存在一个复杂的、动态演变的磁化环境提供了证据。
　　我们发现其宿主星系是约银河系尺度大小、富金属的棒旋星系，同时此FRB所在区域恒星密度较低，处于旋臂之间，距离星系中心中等距离。这种环境与起源于大质量恒星极端爆炸导致的超亮超新星或伽马射线暴后形成的年轻磁星是不一致的。
　　▲ 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.
　　工程学 Engineering Science
　　Aerial additive manufacturing with multiple autonomous robots
　　使用多种自主机器人的空中辅助建造
　　▲ 作者：Ketao Zhang, Pisak Chermprayong, Feng Xiao et al.
　　▲ 链接：
　　https://www.nature.com/articles/s41586-022-04988-4
　　▲ 摘要：
　　我们提供了一个可伸缩的多机器人3D打印和路径规划框架，使机器人的任务和集群规模能够适应整个建筑任务中的打印需求变化。多种机器人的制造框架允许在人工监督下自主三维打印，同时实时评估打印形状和机器行为。
　　为了验证基于该框架的自主空中调幅系统，我们开发了用于在飞行过程中放置材料的建造无人机和用于评估结构质量的扫描无人机，并将通用的实时模型预测控制方案与空中调幅机器人集成在一起。
　　此外，我们将动态自调机械手与建造无人机集成在一起，进一步将制造精度提高到5毫米，以满足精确轨迹要求的打印几何图形，并开发了四种适合连续材料沉积的水泥-聚合物复合混合物。
　　在此，我们演示了概念打印，包括一个由72层快速固化的绝缘泡沫材料组成的2.05米高圆柱体，一个由28层结构伪塑料胶结材料组成的0.18米高圆柱体，一个圆顶形状的光迹虚拟打印以及多机器人模拟情况。空中辅助建造（Aerial-AM）允许在空中进行制造，为未来在危险区、高空或难以到达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.
　　化学 Chemistry
　　Electroreduction of nitrogen with almost 100% current-to-ammonia efficiency
　　近乎100%电流-氨效率的氨生成
　　▲ 作者：Hoang-Long Du, Manjunath Chatti, Rebecca Y. Hodgetts et al.
　　▲ 链接：
　　https://www.nature.com/articles/s41586-022-05108-y
　　▲ 摘要：
　　在此，我们研究了电解质在电化学锂介导的氮还原反应中的作用，并提出了一个在电极-电解质界面区域的紧密离子层可行的高效、稳健的合成方式。该界面由高浓度的亚胺基锂盐电解质产生，提供稳定的氨产率150 ± 20 nmol s−1 cm−2，电流-氨效率接近100%。
　　在电极表面形成的离子组合抑制了电解质的分解，并支持稳定的氮还原。我们的研究强调了锂介导的氮还原反应的性能与电极-电解质界面的物理化学性质之间的相互关系。我们预计，这些发现将指导可持续的稳健、高性能的氨合成开发。
　　▲ 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.
　　地球科学 Earth science
　　Diverse tsunamigenesis triggered by the Hunga Tonga-Hunga Ha’apai eruption
　　汤加洪阿哈阿帕伊岛火山爆发引发的多种海啸成因
　　▲ 作者：Patrick Lynett, Maile McCann, Zili Zhou et al.
　　▲ 链接：
　　https://www.nature.com/articles/s41586-022-05170-6
　　▲ 摘要：
　　在此，我们爆炸喷发通过多种机制产生的波，包括：（1）在火山爆发的附近，空气-海洋与最初的和从爆炸中辐射出来的强大冲击波；（2）水下喷发造成的水腔塌陷；（3）空气-海洋与环绕地球几圈的气压脉冲耦合，导致全球海啸。
　　近场海啸的影响受水腔源的强烈控制，远场海啸异常持久，主要由于气压脉冲机制。几十厘米的幅度也能导致遥远地区港口的灾难性破坏，这意味着海平面适度上升加上未来类似的事件，对基础设施的影响呈阶梯函数增长。
　　将此类事件的复杂情况拼凑起来，对类似地球物理环境下的沿海灾害评估有重要影响，表明了这是一种目前被忽视的全球海啸来源。
　　▲ 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
　　快速移动的大气源解释了汤加火山引发的全球海啸
　　▲ 作者：R. Omira, R. S. Ramalho, J. Kim, P. J. González et al.
　　▲ 链接：
　　https://www.nature.com/articles/s41586-022-04926-4
　　▲ 摘要：
　　在此，我们使用来自全球的海平面、大气和卫星数据，以及数值和分析模型，以证明这场海啸是被一个不断移动的气源所驱动的。
　　在这个气源中，火山喷发造成的声-重力波激发了海洋，并通过共振的方式将能量转移到海洋中。海啸和声-重力波到达时间之间的直接关联证实了这些现象是密切相关的。
　　我们的模型还表明，海啸异常快速的到达时间和漫长的持续时间，以及它的全球范围，与空气-水耦合源一致。这种耦合机制具有明显的危险含义，因为它会导致从深水海域上升的陆地上的海浪更高。
　　▲ 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
　　汤加洪阿哈阿帕伊岛火山爆发导致的地-空大气波
　　▲ 作者：Corwin J. Wright, Neil P. Hindley, M. Joan Alexander et al.
　　▲ 链接：
　　https://www.nature.com/articles/s41586-022-05012-5
　　▲ 摘要：
　　在此，我们使用了一套全面的卫星和地面观测，从地面到电离层对其进行量化，展示汤加火山爆发导致的全球范围波响应的细节。
　　初始爆炸引发了广谱波，其中兰姆波在地表的传播速度为318.2±6 m s−1，在平流层的传播速度为308±5 ~ 319±4 m s−1，重力波在平流层的传播速度为238±3 ~ 269±3 m s−1。
　　此前从未观测到在电离层以下高度的引力波以这种速度传播，或从单一来源传播到整个地球。在超过12小时的时间里，羽流释放的潜热仍然是世界范围内最重要的单个重力波源，在卫星观测中产生了横跨太平洋盆地的圆形波面。
　　在观测记录中，单一源支配如此大的区域也是独一无二的。汤加火山爆发在研究大气如何对突然的点源驱动状态变化作出反应中成为了一个重要的自然实验，将有助于改进天气和气候模型。
　　▲ 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 inpidual 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.