编译|冯维维

Science, 31 JUL 2025，VOLUME 389, ISSUE 6759,

《科学》，2025年7月31日，第389卷，6759期

  ?

化学Chemistry

A molecular machine directs the synthesis of a catenane

分子机器引导索烃合成

▲ 作者：TOMMY WACHSMUTH, ROBERT KLUIFHOOFT, MIRA MüLLER, LEON ZEIS, AND MICHAEL KATHAN

▲链接：

https://www.science.org/doi/10.1126/science.adx5363

▲摘要：

由于分子存在随机的热运动，对分子进行精确的机械操控本质上是困难的。尽管分子尺度的定向运动已经实现，但利用它来赋予分子特定的，尤其是能量上不利的形状并构建机械互锁结构，仍然是一个根本性的挑战。

研究者报道了一种索烃的合成。该合成由一种分子马达驱动，它将分子链缠绕成离散的缠结结构，每个结构由特定数量的机械交叉点定义。光能驱动马达单向旋转，从而实现对一系列热力学上不利但机械结构独特且动力学稳定的缠绕状态的路径依赖控制。

这些状态被共价捕获，随后释放以产生索烃。这种机器导向的方法为无模板构建机械互锁分子提供了一个通用的概念验证策略。

▲ 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.

物理学Chemistry

Dust-driven droplet freezing explains cloud-top phase in the northern extratropics

粉尘驱动液滴冻结有助解释北半球温带地区的云顶相态

▲ 作者：D. VILLANUEVA, M. STENGEL, C. HOOSE, O. BRUNO, K. JEGGLE, A. ANSMANN, AND U. LOHMANN

▲链接：

https://www.science.org/doi/10.1126/science.adt5354

▲摘要：

温度在-39℃到0℃之间的云，其顶部可以覆盖一层液体或冰层，这会影响它们的辐射强迫和降水。冰顶云出现频率（ITF）量化了顶部为冰的云相对于所有云的出现情况，但控制ITF的因素尚不明确。

研究者利用35年的卫星数据发现，在北半球，温度介于-15℃到-30℃之间时，粉尘气溶胶在时间和空间上都与ITF呈现强相关性。此外，研究者发现ITF对温度和粉尘的敏感性比例与实验室测量的液滴冻结结果一致，这表明ITF可归因于粉尘气溶胶。

▲ 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

间隙等离子体腔的声波调制

▲ 作者：SKYLER P. SELVIN, MAJID ESFANDYARPOUR, ANQI JI, YAN JOE LEE, COLIN YULE, MOHAMMAD TAGHINEJAD, AND MARK L. BRONGERSMA

▲链接：

https://www.science.org/doi/10.1126/science.adv1728

▲摘要：

如果能够找到高速电学操控其光学谐振的方法，金属纳米结构在纳米光子学中的作用将得到进一步拓展。研究者利用电驱动的表面声波以及间隙等离子体所提供的极端光场局域增强能力来实现这一目标。

他们将金纳米颗粒置于“颗粒-镜面”构型中，中间间隔一层几纳米厚、可压缩的聚合物隔离层。随后利用表面声波以接近千兆赫兹范围的速度来调谐光散射。观察到的证据表明，表面声波在聚合物中产生了机械形变，随之而来的非线性机械动力学导致了出乎意料的高水平应变和光谱调谐。

研究者表示，该方法为电驱动动态超表面设计以及探索超限域几何结构中聚合物的高频动力学基础研究提供了一种设计策略。

▲ 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中的高场超导光晕

▲ 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

▲链接：

https://www.science.org/doi/10.1126/science.adn7673

▲摘要：

重费米子材料UTe₂是一种候选拓扑超导体，它表现出多个磁场诱导的超导相。其中一个超导相仅在大于40特斯拉的磁场下存在，考虑到其临界温度仅为2开尔文，这个磁场尺度相当可观。

研究者通过测量磁场偏离 bc晶面方向的情况，揭示了该超导相的核心结构：该超导相以一种类似光晕的方式环绕着b轴，并且似乎是由垂直于磁性易轴的磁场分量所稳定的。

这种角度依赖性指向一个具有库珀对有限角动量的多分量自旋三重态序参量。其配对机制仍然令人费解，UTe₂这种特定的亲磁超导倾向似乎与现有的场增强超导性模型不相容。

▲ 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.

生命科学Life Science

Altered translation elongation contributes to key hallmarks of aging in the killifish brain

鳉鱼大脑衰老关键特征的原因

▲ 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

▲链接：

https://www.science.org/doi/10.1126/science.adk3079

▲摘要：

为了解大脑在衰老过程中哪些方面出了问题，研究者通过短寿命的鳉鱼，监测了随着鱼类衰老，蛋白质和RNA丰度、蛋白质溶解度、翻译后修饰以及细胞器组成的变化。

生物体衰老时，蛋白质丰度与转录本丰度的关联性减弱。在鳉鱼中，这种现象似乎与蛋白质稳定性关系较小，而更可能是由翻译过程的改变所影响。富含碱性氨基酸的蛋白质（这是RNA和DNA结合蛋白的一个特征），其翻译过程出现延迟，丰度也随之降低。线粒体组成的变化也被认为是导致衰老过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

行为驱动了人类进化过程中的形态变化

▲ 作者：LUKE D. FANNIN, CHALACHEW M. SEYOUM, VIVEK V. VENKATARAMAN, JUSTIN D. YEAKEL, CHRISTINE M. JANIS, THURE E. CERLING, AND NATHANIEL J. DOMINY

▲链接：

https://www.science.org/doi/10.1126/science.ado2359

▲摘要：

饮食转变和相应的形态变化有时会相继演化，而非同时发生——这一进化过程被称为行为驱动。在化石记录中检测行为驱动具有挑战性，因为很难独立于相应的形态来测量行为。

为了解决这个问题，研究者关注了某些灵长类化石记录中的一个令人费解的行为：食用禾本类植物。他们报告了来自化石灵长类（旧世界猴）的碳和氧同位素比值，并将这些数据整合到对古人类饮食演化的视角中，发现采食禾本类植物的行为变化比相应的牙齿形态变化早了约70万年。

研究者表示，在时间上将饮食和形态变化解耦，有助于确定饮食变化何时以及探索其为何有助于推动人类进化。

▲ 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.