编译|冯维维

Nature, 14 August 2025,Volume 644 Issue 8076

《自然》，2025年8月14日，第644卷，8076期

  ?

物理学Physics

One-third of Sun-like stars are born with misaligned planet-forming disks

1/3类太阳恒星诞生时存在倾斜的行星形成盘

▲ 作者：Lauren I. Biddle, Brendan P. Bowler, Marvin Morgan, Quang H. Tran & Ya-Lin Wu

▲链接：

https://www.nature.com/articles/s41586-025-09324-0

▲摘要：

系外行星呈现出多种多样的轨道构型，这反映了它们的形成过程以及亿万年来通过引力相互作用进行的动力学演化。这段历史被编码在行星系统的角动量结构中——即中心恒星的旋转特性与行星轨道几何之间的关系。

一个主要的可观测特征是恒星自转轴与其行星轨道平面之间的对齐（或倾斜），称为恒星倾角。目前已经测量了数百颗靠近宿主恒星的巨行星的自旋-轨道夹角限制，其中许多揭示了行星存在于倾斜轨道上。一个关键问题随之浮现：恒星倾角主要是源于与系统中其他行星或遥远恒星的引力相互作用？还是“原始的”，即在恒星形成过程中就已形成？

研究者对年轻、孤立的类太阳恒星的自转轴与其原行星盘外部区域方向之间的原始倾角进行了全面评估。大多数系统符合角动量对齐，但约三分之一的孤立年轻系统表现出原始的倾角。这表明，在较老年龄的行星系统中观测到的某些倾角——包括太阳系中太阳与行星之间较为温和的倾角——可能源于其形成时的初始条件。

▲ Abstract：

Exoplanets are organized in a broad array of orbital configurations that reflect their formation along with billions of years of dynamical processing through gravitational interactions. This history is encoded in the angular momentum architecture of planetary systems—the relation between the rotational properties of the central star and the orbital geometry of planets. A primary observable is the alignment (or misalignment) between the rotational axis of the star and the orbital plane of its planets, known as stellar obliquity. Hundreds of spin–orbit constraints have been measured for giant planets close to their host stars, many of which have revealed planets on misaligned orbits. A leading question that has emerged is whether stellar obliquity originates primarily from gravitational interactions with other planets or distant stars in the same system, or if it is ‘primordial’—imprinted during the star-formation process. Here we present a comprehensive assessment of primordial obliquities between the spin axes of young, isolated Sun-like stars and the orientation of the outer regions of their protoplanetary disks. Most systems are consistent with angular momentum alignment but about one-third of isolated young systems exhibit primordial misalignment. This suggests that some obliquities identified in planetary systems at older ages—including the Sun’s modest misalignment with planets in the Solar System—could originate from initial conditions of their formation.

Photophoretic flight of perforated structures in near-space conditions

近地太阳能飞行器来了

▲ 作者：Benjamin C. Schafer, Jong-hyoung Kim, Felix Sharipov, Gyeong-Seok Hwang, Joost J. Vlassak & David W. Keith

▲链接：

https://www.nature.com/articles/s41586-025-09281-8

▲摘要：

光泳是一种气体（或液体）中悬浮的颗粒被光加热后产生的运动力。人们已经知道这种原理超过百年，但直到近期才开始探索它的实际用途。在地球大气层上层，空气十分稀薄，光泳的力强到足以让小型物体漂浮。但迄今为止，大多数实验都集中在非常小而轻的材料上，将之扩展到更大、更实用的大型设备一直是个挑战。

美国哈佛大学的Benjamin Schafer与合作者研究了一种小型太阳能漂浮装置，由两片薄而多孔的膜通过微小的垂直支撑连接而成。结合计算机建模和实验室实验优化光泳力后，他们制作了一个宽1厘米的圆盘，能够在与高空阳光强度相当的光照下悬浮。他们还提出了一种3厘米宽的版本，计算机模型显示它白天在75公里高空能够携带10毫克的载重（足以支撑包含射频天线、太阳能电池和集成电路的小型通信系统）。

这些发现凸显了光泳飞行作为监测地球大气甚至探索其他行星的工具的潜力。作者认为，现在的火星运输成本每公斤超过10万美元，而相比专门的火星卫星，光泳装置在尺寸、重量和功耗方面均有显著优势，未来可用于执行传感和通信任务。未来的设计可以包含导航系统、增加载荷能力和运行时长，以及执行更大规模的任务。

▲ Abstract：

Lightweight nanofabricated structures could photophoretically loft payloads in near-space. Proposed structures range from microscale engineered aerosols, to centimetre-scale thin disks with variations in surface accommodation coefficients, to sandwich structures with nanoscale thickness that might be extended to metre-scale width. Quantitative understanding of how structural and surface properties determine photophoretic lofting forces is necessary to develop a practical flying device. Here we focus on thermal transpiration as the most promising photophoretic mechanism for lofting large devices and present a hybrid analytical–numerical model of the lofting force on a structure that consists of two perforated membranes spaced a small distance apart. We identify optimal structural parameters, including device size, membrane perforation density and distribution of the vertical ligaments that connect the two membranes, each as a function of atmospheric altitude. Targeting these optimal parameters, we fabricate structures with a heterogeneous ligament distribution, which efficiently compromises between structural rigidity and photophoretic performance. We measure how lofting forces generated by these structures depend on pressure using gases with three different molecular weights. We observed photophoretic levitation of a 1-cm-wide structure at an air pressure of 26.7 Pa when illuminated by 750 W m^-2, about 55% the intensity of sunlight. Lastly, we describe the preliminary design of a 3-cm-radius device with 10-mg payload capacity at 75-km altitudes and discuss horizontal motion control, overnight settling, and applications in climate sensing, communications and Martian exploration.

  ?

12,433个实用装置的大气悬浮。向上推力由热对流气流通过装置膜上的434个微尺度孔洞产生。回流发生在远离装置的位置。图片来自：哈佛大学

化学Chemistry

Repurposing haemoproteins for asymmetric metal-catalysed H atom transfer

重新利用血液蛋白进行不对称金属催化的氢原子转移

▲ 作者：Xiang Zhang, Dongping Chen, María álvarez & Thomas R. Ward

▲链接：

https://www.nature.com/articles/s41586-025-09308-0

▲摘要：

过渡金属氢化物已广泛应用于催化羰基、烯烃和炔烃等不饱和基团的加氢功能化。金属氢化物氢原子转移（MHAT）作为非活化烯烃自由基加氢功能化的一种很有前途的策略，弥补了金属氢化物键的异裂作用，从而实现了复杂分子的后期多样化。然而，由于前手性有机自由基与对映纯催化剂之间的弱相互作用，不对称MHAT6仍然具有挑战性。

研究者发现细胞色素P450酶（CYPs）可以被重新利用来催化不对称的MHAT反应，这是一种新的自然反应。P450_BM3的定向进化产生了一个三重突变体，该突变体催化非活化烯烃的MHAT自由基环化，在有氧全细胞条件下产生多种环化合物，包括吡啶和哌啶，其对构象比高达98:2。除了缺电子的烯烃，其他的自由基受体——包括腙、肟和腈——也被重新利用的P450BM3转化为富集对映体的环化产物。

机理研究支持MHAT机制是由一种易逝的铁(III)-氢化物的均溶解理进行的。从CYP119开始，定向进化提供了立体互补的MHATase，突出了重新利用CYPs进行MHAT生物催化的潜力。该研究强调了将均溶金属氢化物反应性整合到金属酶中的前景，从而扩大了不对称自由基生物催化的范围。

▲ Abstract：

Transition metal–hydrides have been widely exploited in catalysis for the hydrofunctionalization of unsaturated moieties, including carbonyls, alkenes and alkynes. To complement heterolytic metal–hydride bond cleavage, metal–hydride hydrogen atom transfer (MHAT) has recently gained attention, as a promising strategy for radical hydrofunctionalization of unactivated alkenes, thus enabling late-stage diversification of complex molecules. However, owing to the weak interactions between the prochiral organic radical and the enantiopure catalyst, asymmetric MHAT6 remains challenging. Here we show that cytochrome P450 enzymes (CYPs) can be repurposed to catalyse asymmetric MHAT, a new-to-nature reaction. Directed evolution of P450_BM3 yielded a triple mutant that catalyses MHAT radical cyclization of unactivated alkenes, producing diverse cyclic compounds—including pyrrolidines and piperidines—with up to 98:2 enantiomeric ratio under aerobic whole-cell conditions. Apart from electron-deficient alkenes, alternative radical acceptors—including hydrazones, oximes and nitriles—were converted by repurposed P450_BM3 to enantioenriched cyclization products. Mechanistic investigations support an MHAT mechanism proceeding by homolytic cleavage of a fleeting iron(III)–hydride species. Starting from CYP119, directed evolution afforded a stereocomplementary MHATase, highlighting the potential of repurposed CYPs for MHAT biocatalysis. Our study highlights the prospect of integrating homolytic metal–hydride reactivity into metalloenzymes, thus expanding the scope of asymmetric radical biocatalysis.

Direct identification of Ac and No molecules with an atom-at-a-time technique

利用单原子级技术直接鉴定锕和锘分子

▲ 作者：Jennifer L. Pore, Jacklyn M. Gates, David A. Dixon, Fatima H. Garcia, John K. Gibson, John A. Gooding, Mallory McCarthy, Rodney Orford, Ziad Shafi, David K. Shuh & Sarah Sprouse

▲链接：

https://www.nature.com/articles/s41586-025-09342-y

▲摘要：

元素周期表为理解化学性质提供了一个直观的框架。然而，对于位于周期表底部的最重元素，其传统的规律模式可能会被打破。锕系元素（原子序数Z>88）和超重元素（Z≥104）的巨大原子核会引起相对论效应，预计这将大幅改变它们的化学行为，这可能表明人们已经到达了可预测元素周期表的终点。

与镧系元素相比，锕系元素表现出的异常化学性质已被归因于相对论效应。遗憾的是，由于对后序锕系元素和超重元素的研究稀少，研究者难以全面理解相对论效应的全部影响。在镄（Z=100）之后的元素，需要使用加速离子束和最先进的实验方法进行单原子级的合成与研究。迄今为止，尚没有任何实验能够直接鉴定所产生的分子物种。

研究者在劳伦斯伯克利国家实验室的88英寸回旋加速器设施中，通过核反应合成了锕（Ac）和锘（No）的离子，并将其暴露于痕量的H₂O和N₂中。随后，利用 FIONA（用于鉴定核素A的装置）测量其质荷比，从而直接鉴定了所产生的分子物种。

研究者表示，这些结果标志着首次利用单原子级技术直接鉴定重元素分子物种，并突显了此类鉴定在未来超重元素化学实验中的重要性，以深化对其化学性质的认识。

▲ Abstract：

The periodic table provides an intuitive framework for understanding chemical properties. However, its traditional patterns may break down for the heaviest elements occupying the bottom of the chart. The large nuclei of actinides (Z > 88) and superheavy elements (Z ≥ 104) give rise to relativistic effects that are expected to substantially alter their chemical behaviours, potentially indicating that we have reached the end of a predictive periodic table1. Relativistic effects have already been cited for the unusual chemistry of the actinides compared with those of their lanthanide counterparts2. Unfortunately, it is difficult to understand the full impact of relativistic effects, as research on the later actinides and superheavy elements is scarce. Beyond fermium (Z = 100), elements need to be produced and studied one atom at a time, using accelerated ion beams and state-of-the-art experimental approaches. So far, no experiments have been capable of directly identifying produced molecular species. Here ions of actinium (Ac, Z = 89) and nobelium (No, Z = 102) were synthesized through nuclear reactions at the 88-Inch Cyclotron facility at Lawrence Berkeley National Laboratory and then exposed to trace amounts of H₂O and N₂. The produced molecular species were directly identified by measuring their mass-to-charge ratios using FIONA (For the Identification Of Nuclide A). These results mark the first, to our knowledge, direct identification of heavy-element molecular species using an atom-at-a-time technique and highlight the importance of such identifications in future superheavy-element chemistry experiments to deepen understanding of their chemical properties.

水文学Hydrology

Extreme river flood exposes latent erosion risk

极端河流洪水暴露潜在侵蚀风险

▲ 作者：H. J. Barneveld, R. M. Frings, E. Mosselman, J. G. Venditti, M. G. Kleinhans, A. Blom, R. M. J. Schielen, W. H. J. Toonen, D. Meijer, A. J. Paarlberg, R. P. van Denderen, J. S. de Jong, J. G. W. Beemster, L. A. Melsen & A. J. F. Hoitink

▲链接：

https://www.nature.com/articles/s41586-025-09305-3

▲摘要：

气候变化预计将增加河流洪水的频率和强度。洪水不仅通过淹没和人员伤亡造成破坏，还会因岸堤失稳和河床侵蚀过程而危及基础设施，而这些过程目前尚不完全清楚。常见的防洪安全计划包括堤防加固和河道拓宽。2021年发生在默兹河流域的洪水导致43人死亡，并对基础设施造成数十亿美元的损失。

研究者基于对默兹河洪水的分析，揭示了河道的不均匀拓宽以及河床下方沉积物的非均质性如何导致大规模侵蚀。

一项近期的防洪安全计划拓宽了河道，但在某些瓶颈段，拓宽要么被基础设施阻挡，要么尚未实施。构造抬升加剧了河床侵蚀，该抬升形成了覆盖在细粒沉积物之上的薄层表砾层。

在这些瓶颈段，流速急剧增加，形成了带波谷的水下沙丘。这些沙丘的波谷击穿了砾石保护层，暴露出易受侵蚀的沙层，最终形成了极深的冲刷坑，其中一个深度超过15米。

作者表示，该研究凸显了在气候变化、洪水风险加剧以及河道拓宽空间竞争加剧的背景下，河道再工程化所面临的挑战。同时，该研究也呼吁亟需加强对河床下伏地层的研究与理解。

▲ Abstract：

Climate change is expected to increase the frequency and magnitude of river floods. Floods not only cause damage by inundation and loss of life but also jeopardize infrastructure because of bank failure and riverbed erosion processes that are poorly understood. Common flood safety programmes include dyke reinforcement and river widening. The 2021 flood in the Meuse Basin caused 43 fatalities and billions of dollars of damage to infrastructure. Here, on the basis of analysis of the Meuse flood, we show how uneven widening of the river and heterogeneity of sediment deposits under the river can cause massive erosion. A recent flood safety programme widened the river but created bottlenecks where widening was either prevented by infrastructure or not yet implemented. Riverbed erosion was exacerbated by tectonic uplift that had produced a thin top gravel layer above fine-grained sediment. Greatly enhanced flow velocities produced underwater dunes with troughs that broke through the gravel armour in the bottlenecks, exposing easily erodible sands, resulting in extreme scour holes, one more than 15 m deep. Our investigation highlights the challenges of re-engineering rivers in the face of climate change, increased flood risks and competition for river widening space, and calls for a better understanding of the subsurface.

Calving-driven fjord dynamics resolved by seafloor fibre sensing

海底光纤传感解析冰川崩解驱动的峡湾动力学成

▲ 作者：Dominik Gräff, Bradley Paul Lipovsky, Andreas Vieli, Armin Dachauer, Rebecca Jackson, Daniel Farinotti, Julia Schmale, Jean-Paul Ampuero, Eric Berg, Anke Dannowski, Andrea Kneib-Walter, Manuela Köpfli, Heidrun Kopp, Enrico van der Loo, Daniel Mata Flores, Diego Mercerat, Raphael Moser, Anthony Sladen, Fabian Walter, Diego Wasser, Ethan Welty, Selina Wetter & Ethan F. Williams

▲链接：

https://www.nature.com/articles/s41586-025-09347-7

▲摘要：

融冰与变暖海洋之间的相互作用驱动着格陵兰潮水冰川当前的退缩，这对海平面上升和全球气候系统均产生影响。这些冰-海相互作用控制着冰川前缘消融，涉及一系列将冰川崩解——即冰山的分离——和海底融化与更广泛的峡湾动力学联系起来的小尺度过程链。

然而，对这些过程的理解仍然有限，这在很大程度上是由于难以在崩解前沿附近危险环境中进行具有足够时空分辨率的针对性观测。

研究者揭示了冰山崩解可通过激发瞬态内波而充当海底融化的放大器。他们的观测基于对冰山崩解过程链进行的近前缘海底光纤传感。在这一过程链中，崩解始于持续的冰体破裂，这些破裂汇聚导致冰山分离；冰山分离进而激发局地海啸、内重力波以及冰前缘的瞬变流，最终冰山碎裂成块。

他们的观测揭示了潮水冰川与变暖海洋相互作用的先前未知的路径，并有助于闭合冰前消融收支——这是当前模型难以做到的。这些见解提供了关乎全球范围内正在退缩的潮水冰川的全新过程尺度理解。

▲ Abstract：

Interactions between melting ice and a warming ocean drive the present-day retreat of tidewater glaciers of Greenland, with consequences for both sea level rise and the global climate system5. Controlling glacier frontal ablation, these ice–ocean interactions involve chains of small-scale processes that link glacier calving—the detachment of icebergs6—and submarine melt to the broader fjord dynamics. However, understanding these processes remains limited, in large part due to the challenge of making targeted observations in hazardous environments near calving fronts with sufficient temporal and spatial resolution. Here we show that iceberg calving can act as a submarine melt amplifier through excitation of transient internal waves. Our observations are based on front-proximal submarine fibre sensing of the iceberg calving process chain. In this chain, calving initiates with persistent ice fracturing that coalesces into iceberg detachment, which in turn excites local tsunamis, internal gravity waves and transient currents at the ice front before the icebergs eventually decay into fragments. Our observations show previously unknown pathways in which tidewater glaciers interact with a warming ocean and help close the ice front ablation budget, which current models struggle to do. These insights provide new process-scale understanding pertinent to retreating tidewater glaciers around the globe.