編譯|馮維維
Science, 31 JUL 2025，VOLUME 389, ISSUE 6759,
《科學》，2025年7月31日，第389卷，6759期
化學Chemistry
A molecular machine directs the synthesis of a catenane
分子機器引導索烴合成
▲ 作者：TOMMY WACHSMUTH, ROBERT KLUIFHOOFT, MIRA MüLLER, LEON ZEIS, AND MICHAEL KATHAN
▲鏈接：
https://www.science.org/doi/10.1126/science.adx5363
▲摘要：
由于分子存在隨機的熱運動，對分子進行精確的機械操控本質上是困難的。盡管分子尺度的定向運動已經實現，但利用它來賦予分子特定的，尤其是能量上不利的形狀并構建機械互鎖結構，仍然是一個根本性的挑戰。
研究者報道了一種索烴的合成。該合成由一種分子馬達驅動，它將分子鏈纏繞成離散的纏結結構，每個結構由特定數量的機械交叉點定義。光能驅動馬達單向旋轉，從而實現對一系列熱力學上不利但機械結構獨特且動力學穩定的纏繞狀態的路徑依賴控制。
這些狀態被共價捕獲，隨后釋放以產生索烴。這種機器導向的方法為無模板構建機械互鎖分子提供了一個通用的概念驗證策略。
▲ Abstract：
Precise mechanical manipulation of molecules is inherently difficult owing to random thermal motion. Although directed movement on the molecular scale has been achieved, using it to impose specific—especially energetically disfavored—shapes on molecules and construct mechanically interlocked structures remains a fundamental challenge. In this study, we report the synthesis of a catenane enabled by a molecular motor that winds molecular strands into discrete entangled structures, each defined by a specific number of mechanical crossings. Light energy drives unidirectional motor rotation, enabling path-dependent control over a sequence of thermodynamically disfavored yet mechanically distinct and kinetically stable winding states, which are covalently captured and subsequently released to yield a catenane. This machine-directed approach offers a general proof-of-concept strategy for the template-free construction of mechanically interlocked molecules.
物理學Chemistry
Dust-driven droplet freezing explains cloud-top phase in the northern extratropics
粉塵驅動液滴凍結有助解釋北半球溫帶地區的云頂相態
▲ 作者：D. VILLANUEVA, M. STENGEL, C. HOOSE, O. BRUNO, K. JEGGLE, A. ANSMANN, AND U. LOHMANN
▲鏈接：
https://www.science.org/doi/10.1126/science.adt5354
▲摘要：
溫度在-39℃到0℃之間的云，其頂部可以覆蓋一層液體或冰層，這會影響它們的輻射強迫和降水。冰頂云出現頻率（ITF）量化了頂部為冰的云相對于所有云的出現情況，但控制ITF的因素尚不明確。
研究者利用35年的衛星數據發現，在北半球，溫度介于-15℃到-30℃之間時，粉塵氣溶膠在時間和空間上都與ITF呈現強相關性。此外，研究者發現ITF對溫度和粉塵的敏感性比例與實驗室測量的液滴凍結結果一致，這表明ITF可歸因于粉塵氣溶膠。
▲ Abstract：
Clouds between -39° and 0°C can be topped by a liquid or ice layer, which affects their radiative forcing and precipitation. The cloud-top ice-to-total frequency (ITF) quantifies the occurrence of clouds with an ice top relative to total cloud occurrence, but the factors controlling ITF are poorly understood. Using 35 years of satellite data, we show that in the Northern Hemisphere, between -15° and -30°C, dust aerosol is strongly correlated with ITF in both time and space. Furthermore, we found that the sensitivities of ITF to temperature and dust are in a ratio that agrees with laboratory measurements of droplet freezing, showing that ITF can be attributed to dust aerosol.
Acoustic wave modulation of gap plasmon cavities
間隙等離子體腔的聲波調制
▲ 作者：SKYLER P. SELVIN, MAJID ESFANDYARPOUR, ANQI JI, YAN JOE LEE, COLIN YULE, MOHAMMAD TAGHINEJAD, AND MARK L. BRONGERSMA
▲鏈接：
https://www.science.org/doi/10.1126/science.adv1728
▲摘要：
如果能夠找到高速電學操控其光學諧振的方法，金屬納米結構在納米光子學中的作用將得到進一步拓展。研究者利用電驅動的表面聲波以及間隙等離子體所提供的極端光場局域增強能力來實現這一目標。
他們將金納米顆粒置于“顆粒-鏡面”構型中，中間間隔一層幾納米厚、可壓縮的聚合物隔離層。隨后利用表面聲波以接近千兆赫茲范圍的速度來調諧光散射。觀察到的證據表明，表面聲波在聚合物中產生了機械形變，隨之而來的非線性機械動力學導致了出乎意料的高水平應變和光譜調諧。
研究者表示，該方法為電驅動動態超表面設計以及探索超限域幾何結構中聚合物的高頻動力學基礎研究提供了一種設計策略。
▲ Abstract：
The important role of metallic nanostructures in nanophotonics will expand if ways to electrically manipulate their optical resonances at high speed can be identified. We capitalized on electrically driven surface acoustic waves and the extreme light concentration afforded by gap plasmons to achieve this goal. We placed gold nanoparticles in a particle-on-mirror configuration with a few-nanometer-thick, compressible polymer spacer. Surface acoustic waves were then used to tune light scattering at speeds approaching the gigahertz regime. We observed evidence that the surface acoustic waves produced mechanical deformations in the polymer and that ensuing nonlinear mechanical dynamics led to unexpectedly large levels of strain and spectral tuning. Our approach provides a design strategy for electrically driven dynamic metasurfaces and fundamental explorations of high-frequency, polymer dynamics in ultraconfined geometries.
High-field superconducting halo in UTe2
UTe2中的高場超導光暈
▲ 作者：SYLVIA K. LEWIN, PETER CZAJKA, COREY E. FRANK, GICELA SAUCEDO SALAS, G. TIMOTHY NOE II, HYEOK YOON, YUN SUK EO, JOHNPIERRE PAGLIONE, ANDRIY H. NEVIDOMSKYY, AND NICHOLAS P. BUTCH
▲鏈接：
https://www.science.org/doi/10.1126/science.adn7673
▲摘要：
重費米子材料UTe2是一種候選拓撲超導體，它表現出多個磁場誘導的超導相。其中一個超導相僅在大于40特斯拉的磁場下存在，考慮到其臨界溫度僅為2開爾文，這個磁場尺度相當可觀。
研究者通過測量磁場偏離 bc晶面方向的情況，揭示了該超導相的核心結構：該超導相以一種類似光暈的方式環繞著b軸，并且似乎是由垂直于磁性易軸的磁場分量所穩定的。
這種角度依賴性指向一個具有庫珀對有限角動量的多分量自旋三重態序參量。其配對機制仍然令人費解，UTe2這種特定的親磁超導傾向似乎與現有的場增強超導性模型不相容。
▲ Abstract：
The heavy fermion material UTe2 is a candidate topological superconductor that exhibits multiple magnetic field–induced superconducting phases. One such phase exists only at fields greater than 40 tesla, a considerable scale given its critical temperature of only 2 K. Here, we extend measurements of this state with fields outside of the bc crystallographic plane and reveal its core structure: The superconducting phase wraps around the b axis in a halo-like fashion and appears to be stabilized by a field component perpendicular to the magnetic easy axis. This angle dependence points to a multicomponent spin-triplet order parameter with a finite angular momentum of the Cooper pairs. The pairing mechanism remains enigmatic, and UTe2’s specific magnetophilic superconducting tendencies seem incompatible with existing models for field-enhanced superconductivity.
生命科學Life Science
Altered translation elongation contributes to key hallmarks of aging in the killifish brain
鳉魚大腦衰老關鍵特征的原因
▲ 作者：DOMENICO DI FRAIA, ANTONIO MARINO, JAE HO LEE, ERIKA KELMER SACRAMENTO, MARIO BAUMGART, SARA BAGNOLI, TILL BALLA, FELIX SCHALK, STEPHAN KAMRAD, AND ALESSANDRO ORI
▲鏈接：
https://www.science.org/doi/10.1126/science.adk3079
▲摘要：
為了解大腦在衰老過程中哪些方面出了問題，研究者通過短壽命的鳉魚，監測了隨著魚類衰老，蛋白質和RNA豐度、蛋白質溶解度、翻譯后修飾以及細胞器組成的變化。
生物體衰老時，蛋白質豐度與轉錄本豐度的關聯性減弱。在鳉魚中，這種現象似乎與蛋白質穩定性關系較小，而更可能是由翻譯過程的改變所影響。富含堿性氨基酸的蛋白質（這是RNA和DNA結合蛋白的一個特征），其翻譯過程出現延遲，豐度也隨之降低。線粒體組成的變化也被認為是導致衰老過程中功能衰退的可能因素。
▲ Abstract：
To get a handle on what falls apart during aging in the brain, Di Fraia et al. turned to the short-lived killifish (see the Perspective by Dionne and Laurent). The authors monitored changes in protein and RNA abundance, protein solubility, post-translational modification, and organelle composition as the fish aged. As organisms age, protein abundance is less closely coupled to transcript abundance. In the fish, this appeared to have less to do with protein stability and was more likely influenced by altered translation. Proteins rich in basic amino acids, a characteristic of RNA and DNA binding proteins, had delays in translation and decreased in abundance. Changes in mitochondrial composition were also noted as likely contributors to loss of function in aging.
Behavior drives morphological change during human evolution
行為驅動了人類進化過程中的形態變化
▲ 作者：LUKE D. FANNIN, CHALACHEW M. SEYOUM, VIVEK V. VENKATARAMAN, JUSTIN D. YEAKEL, CHRISTINE M. JANIS, THURE E. CERLING, AND NATHANIEL J. DOMINY
▲鏈接：
https://www.science.org/doi/10.1126/science.ado2359
▲摘要：
飲食轉變和相應的形態變化有時會相繼演化，而非同時發生——這一進化過程被稱為行為驅動。在化石記錄中檢測行為驅動具有挑戰性，因為很難獨立于相應的形態來測量行為。
為了解決這個問題，研究者關注了某些靈長類化石記錄中的一個令人費解的行為：食用禾本類植物。他們報告了來自化石靈長類（舊世界猴）的碳和氧同位素比值，并將這些數據整合到對古人類飲食演化的視角中，發現采食禾本類植物的行為變化比相應的牙齒形態變化早了約70萬年。
研究者表示，在時間上將飲食和形態變化解耦，有助于確定飲食變化何時以及探索其為何有助于推動人類進化。
▲ Abstract：
Dietary shifts and corresponding morphological changes can sometimes evolve in succession, not concurrently—an evolutionary process called behavioral drive. Detecting behavioral drive in the fossil record is challenging because it is difficult to measure behaviors independently from corresponding morphologies. To solve this problem, we focused on a puzzling behavior in the fossil record of some primates: eating graminoid plants. We report carbon and oxygen isotope ratios from fossil cercopithecid monkeys and integrate the data into a view of hominin dietary evolution, finding that changes in graminivorous behavior preceded corresponding changes in dental morphology by ~700,000 years. Decoupling diets and morphologies in time was conducive to determining when and to exploring why dietary changes helped to propel human evolution.
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