編譯|馮維維
Nature, 14 August 2025,Volume 644 Issue 8076
《自然》，2025年8月14日，第644卷，8076期
物理學(xué)Physics
One-third of Sun-like stars are born with misaligned planet-forming disks
1/3類太陽恒星誕生時存在傾斜的行星形成盤
▲ 作者：Lauren I. Biddle, Brendan P. Bowler, Marvin Morgan, Quang H. Tran & Ya-Lin Wu
▲鏈接：
https://www.nature.com/articles/s41586-025-09324-0
▲摘要：
系外行星呈現(xiàn)出多種多樣的軌道構(gòu)型，這反映了它們的形成過程以及億萬年來通過引力相互作用進(jìn)行的動力學(xué)演化。這段歷史被編碼在行星系統(tǒng)的角動量結(jié)構(gòu)中——即中心恒星的旋轉(zhuǎn)特性與行星軌道幾何之間的關(guān)系。
一個主要的可觀測特征是恒星自轉(zhuǎn)軸與其行星軌道平面之間的對齊（或傾斜），稱為恒星傾角。目前已經(jīng)測量了數(shù)百顆靠近宿主恒星的巨行星的自旋-軌道夾角限制，其中許多揭示了行星存在于傾斜軌道上。一個關(guān)鍵問題隨之浮現(xiàn)：恒星傾角主要是源于與系統(tǒng)中其他行星或遙遠(yuǎn)恒星的引力相互作用？還是“原始的”，即在恒星形成過程中就已形成？
研究者對年輕、孤立的類太陽恒星的自轉(zhuǎn)軸與其原行星盤外部區(qū)域方向之間的原始傾角進(jìn)行了全面評估。大多數(shù)系統(tǒng)符合角動量對齊，但約三分之一的孤立年輕系統(tǒng)表現(xiàn)出原始的傾角。這表明，在較老年齡的行星系統(tǒng)中觀測到的某些傾角——包括太陽系中太陽與行星之間較為溫和的傾角——可能源于其形成時的初始條件。
▲ 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
近地太陽能飛行器來了
▲ 作者：Benjamin C. Schafer, Jong-hyoung Kim, Felix Sharipov, Gyeong-Seok Hwang, Joost J. Vlassak & David W. Keith
▲鏈接：
https://www.nature.com/articles/s41586-025-09281-8
▲摘要：
光泳是一種氣體（或液體）中懸浮的顆粒被光加熱后產(chǎn)生的運動力。人們已經(jīng)知道這種原理超過百年，但直到近期才開始探索它的實際用途。在地球大氣層上層，空氣十分稀薄，光泳的力強到足以讓小型物體漂浮。但迄今為止，大多數(shù)實驗都集中在非常小而輕的材料上，將之?dāng)U展到更大、更實用的大型設(shè)備一直是個挑戰(zhàn)。
美國哈佛大學(xué)的Benjamin Schafer與合作者研究了一種小型太陽能漂浮裝置，由兩片薄而多孔的膜通過微小的垂直支撐連接而成。結(jié)合計算機(jī)建模和實驗室實驗優(yōu)化光泳力后，他們制作了一個寬1厘米的圓盤，能夠在與高空陽光強度相當(dāng)?shù)墓庹障聭腋 Ｋ麄冞€提出了一種3厘米寬的版本，計算機(jī)模型顯示它白天在75公里高空能夠攜帶10毫克的載重（足以支撐包含射頻天線、太陽能電池和集成電路的小型通信系統(tǒng)）。
這些發(fā)現(xiàn)凸顯了光泳飛行作為監(jiān)測地球大氣甚至探索其他行星的工具的潛力。作者認(rèn)為，現(xiàn)在的火星運輸成本每公斤超過10萬美元，而相比專門的火星衛(wèi)星，光泳裝置在尺寸、重量和功耗方面均有顯著優(yōu)勢，未來可用于執(zhí)行傳感和通信任務(wù)。未來的設(shè)計可以包含導(dǎo)航系統(tǒng)、增加載荷能力和運行時長，以及執(zhí)行更大規(guī)模的任務(wù)。
▲ 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個實用裝置的大氣懸浮。向上推力由熱對流氣流通過裝置膜上的434個微尺度孔洞產(chǎn)生。回流發(fā)生在遠(yuǎn)離裝置的位置。圖片來自：哈佛大學(xué)
化學(xué)Chemistry
Repurposing haemoproteins for asymmetric metal-catalysed H atom transfer
重新利用血液蛋白進(jìn)行不對稱金屬催化的氫原子轉(zhuǎn)移
▲ 作者：Xiang Zhang, Dongping Chen, María álvarez & Thomas R. Ward
▲鏈接：
https://www.nature.com/articles/s41586-025-09308-0
▲摘要：
過渡金屬氫化物已廣泛應(yīng)用于催化羰基、烯烴和炔烴等不飽和基團(tuán)的加氫功能化。金屬氫化物氫原子轉(zhuǎn)移（MHAT）作為非活化烯烴自由基加氫功能化的一種很有前途的策略，彌補了金屬氫化物鍵的異裂作用，從而實現(xiàn)了復(fù)雜分子的后期多樣化。然而，由于前手性有機(jī)自由基與對映純催化劑之間的弱相互作用，不對稱MHAT6仍然具有挑戰(zhàn)性。
研究者發(fā)現(xiàn)細(xì)胞色素P450酶（CYPs）可以被重新利用來催化不對稱的MHAT反應(yīng)，這是一種新的自然反應(yīng)。P450BM3的定向進(jìn)化產(chǎn)生了一個三重突變體，該突變體催化非活化烯烴的MHAT自由基環(huán)化，在有氧全細(xì)胞條件下產(chǎn)生多種環(huán)化合物，包括吡啶和哌啶，其對構(gòu)象比高達(dá)98:2。除了缺電子的烯烴，其他的自由基受體——包括腙、肟和腈——也被重新利用的P450BM3轉(zhuǎn)化為富集對映體的環(huán)化產(chǎn)物。
機(jī)理研究支持MHAT機(jī)制是由一種易逝的鐵(III)-氫化物的均溶解理進(jìn)行的。從CYP119開始，定向進(jìn)化提供了立體互補的MHATase，突出了重新利用CYPs進(jìn)行MHAT生物催化的潛力。該研究強調(diào)了將均溶金屬氫化物反應(yīng)性整合到金屬酶中的前景，從而擴(kuò)大了不對稱自由基生物催化的范圍。
▲ 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 P450BM3 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 P450BM3 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
利用單原子級技術(shù)直接鑒定錒和锘分子
▲ 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
▲鏈接：
https://www.nature.com/articles/s41586-025-09342-y
▲摘要：
元素周期表為理解化學(xué)性質(zhì)提供了一個直觀的框架。然而，對于位于周期表底部的最重元素，其傳統(tǒng)的規(guī)律模式可能會被打破。錒系元素（原子序數(shù)Z>88）和超重元素（Z≥104）的巨大原子核會引起相對論效應(yīng)，預(yù)計這將大幅改變它們的化學(xué)行為，這可能表明人們已經(jīng)到達(dá)了可預(yù)測元素周期表的終點。
與鑭系元素相比，錒系元素表現(xiàn)出的異常化學(xué)性質(zhì)已被歸因于相對論效應(yīng)。遺憾的是，由于對后序錒系元素和超重元素的研究稀少，研究者難以全面理解相對論效應(yīng)的全部影響。在鐨（Z=100）之后的元素，需要使用加速離子束和最先進(jìn)的實驗方法進(jìn)行單原子級的合成與研究。迄今為止，尚沒有任何實驗?zāi)軌蛑苯予b定所產(chǎn)生的分子物種。
研究者在勞倫斯伯克利國家實驗室的88英寸回旋加速器設(shè)施中，通過核反應(yīng)合成了錒（Ac）和锘（No）的離子，并將其暴露于痕量的H2O和N2中。隨后，利用 FIONA（用于鑒定核素A的裝置）測量其質(zhì)荷比，從而直接鑒定了所產(chǎn)生的分子物種。
研究者表示，這些結(jié)果標(biāo)志著首次利用單原子級技術(shù)直接鑒定重元素分子物種，并突顯了此類鑒定在未來超重元素化學(xué)實驗中的重要性，以深化對其化學(xué)性質(zhì)的認(rèn)識。
▲ 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.
水文學(xué)Hydrology
Extreme river flood exposes latent erosion risk
極端河流洪水暴露潛在侵蝕風(fēng)險
▲ 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
▲鏈接：
https://www.nature.com/articles/s41586-025-09305-3
▲摘要：
氣候變化預(yù)計將增加河流洪水的頻率和強度。洪水不僅通過淹沒和人員傷亡造成破壞，還會因岸堤失穩(wěn)和河床侵蝕過程而危及基礎(chǔ)設(shè)施，而這些過程目前尚不完全清楚。常見的防洪安全計劃包括堤防加固和河道拓寬。2021年發(fā)生在默茲河流域的洪水導(dǎo)致43人死亡，并對基礎(chǔ)設(shè)施造成數(shù)十億美元的損失。
研究者基于對默茲河洪水的分析，揭示了河道的不均勻拓寬以及河床下方沉積物的非均質(zhì)性如何導(dǎo)致大規(guī)模侵蝕。
一項近期的防洪安全計劃拓寬了河道，但在某些瓶頸段，拓寬要么被基礎(chǔ)設(shè)施阻擋，要么尚未實施。構(gòu)造抬升加劇了河床侵蝕，該抬升形成了覆蓋在細(xì)粒沉積物之上的薄層表礫層。
在這些瓶頸段，流速急劇增加，形成了帶波谷的水下沙丘。這些沙丘的波谷擊穿了礫石保護(hù)層，暴露出易受侵蝕的沙層，最終形成了極深的沖刷坑，其中一個深度超過15米。
作者表示，該研究凸顯了在氣候變化、洪水風(fēng)險加劇以及河道拓寬空間競爭加劇的背景下，河道再工程化所面臨的挑戰(zhàn)。同時，該研究也呼吁亟需加強對河床下伏地層的研究與理解。
▲ 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
海底光纖傳感解析冰川崩解驅(qū)動的峽灣動力學(xué)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
▲鏈接：
https://www.nature.com/articles/s41586-025-09347-7
▲摘要：
融冰與變暖海洋之間的相互作用驅(qū)動著格陵蘭潮水冰川當(dāng)前的退縮，這對海平面上升和全球氣候系統(tǒng)均產(chǎn)生影響。這些冰-海相互作用控制著冰川前緣消融，涉及一系列將冰川崩解——即冰山的分離——和海底融化與更廣泛的峽灣動力學(xué)聯(lián)系起來的小尺度過程鏈。
然而，對這些過程的理解仍然有限，這在很大程度上是由于難以在崩解前沿附近危險環(huán)境中進(jìn)行具有足夠時空分辨率的針對性觀測。
研究者揭示了冰山崩解可通過激發(fā)瞬態(tài)內(nèi)波而充當(dāng)海底融化的放大器。他們的觀測基于對冰山崩解過程鏈進(jìn)行的近前緣海底光纖傳感。在這一過程鏈中，崩解始于持續(xù)的冰體破裂，這些破裂匯聚導(dǎo)致冰山分離；冰山分離進(jìn)而激發(fā)局地海嘯、內(nèi)重力波以及冰前緣的瞬變流，最終冰山碎裂成塊。
他們的觀測揭示了潮水冰川與變暖海洋相互作用的先前未知的路徑，并有助于閉合冰前消融收支——這是當(dāng)前模型難以做到的。這些見解提供了關(guān)乎全球范圍內(nèi)正在退縮的潮水冰川的全新過程尺度理解。
▲ 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.
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