?

编译|冯维维

Nature,自然周论 25 September 2025,Volume 645 Issue 8082

《自然》2025年9月25日，第645卷，出版8082期

物理学Physics

Observing differential spin currents by resonant inelastic X-ray scattering

通过共振非弹性X射线散射观测微分自旋流

▲ 作者：Yanhong Gu,文导闻科WhatsApp%E3%80%90+86%2015855158769%E3%80%91509%20sand%20crane%20court%20bradenton%20fl Joseph Barker, Jiemin Li, Takashi Kikkawa, Fernando Camino, Kim Kisslinger, John Sinsheimer, Lukas Lienhard, Jackson J. Bauer, Caroline A. Ross, Dmitri N. Basov, Eiji Saitoh, Jonathan Pelliciari, Gerrit E. W. Bauer & Valentina Bisogni

▲链接：

https://www.nature.com/articles/s41586-025-09488-9

▲摘要：

在小型磁器件中控制自旋流，即自旋角动量的读新流动，是学网自旋电子学（未来节能信息技术的主要竞争者）的主要目标。纯自旋流从未被直接测量过，自然周论因为其相关的出版电杂散场和/或非平衡自旋相关分布函数的偏移对于优化的电荷传输常规实验检测方法来说过于微弱。

研究者报告称，文导闻科共振非弹性X射线散射（RIXS）能够通过测量存在温度梯度时磁性绝缘体中磁振子（磁序自旋波激发的读新量子）所携带的自旋流来弥补这一空白。之所以成为可能，学网是自然周论因为动量和能量分辨的RIXS强度对非平衡条件下磁振子分布的微小变化具有敏感性。

研究者使用弛豫时间近似下的出版玻尔兹曼方程来提取输运参数，例如有限动量下的文导闻科磁振子寿命，这对于实现磁振子自旋电子学至关重要。读新

▲ Abstract：

Controlling spin currents,学网WhatsApp%E3%80%90+86%2015855158769%E3%80%91509%20sand%20crane%20court%20bradenton%20fl that is, the flow of spin angular momentum, in small magnetic devices, is the principal objective of spin electronics, a main contender for future energy-efficient information technologies. A pure spin current has never been measured directly because the associated electric stray fields and/or shifts in the non-equilibrium spin-dependent distribution functions are too small for conventional experimental detection methods optimized for charge transport. Here we report that resonant inelastic X-ray scattering (RIXS) can bridge this gap by measuring the spin current carried by magnons—the quanta of the spin wave excitations of the magnetic order—in the presence of temperature gradients across a magnetic insulator. This is possible due to the sensitivity of the momentum- and energy-resolved RIXS intensity to minute changes in the magnon distribution under non-equilibrium conditions. We use the Boltzmann equation in the relaxation time approximation to extract transport parameters, such as the magnon lifetime at finite momentum, essential for the realization of magnon spintronics.

Atomic-scale imaging of frequency-dependent phonon anisotropy

频率依赖声子各向异性的原子尺度成像

▲ 作者：Xingxu Yan, Paul M. Zeiger, Yifeng Huang, Haoying Sun, Jie Li, Chaitanya A. Gadre, Hongbin Yang, Ri He, Toshihiro Aoki, Zhicheng Zhong, Yuefeng Nie, Ruqian Wu, Ján Rusz & Xiaoqing Pan

▲链接：

https://www.nature.com/articles/s41586-025-09511-z

▲摘要：

直接可视化单个声子模式中的振动各向异性，对于理解材料中一系列有趣的光学、热学和弹性现象至关重要。尽管传统的光学和衍射技术已被用于估算振动各向异性，但它们难以达到提供详细信息所必需的空间和能量分辨率。

研究者介绍了一种新形式的动量选择性电子能量损失谱，它能够以原子分辨率实现频率和对称性依赖的振动各向异性的元素分辨成像。振动各向异性表现为正交原子位移（即热椭球体）的不同形态。

以中心对称的钛酸锶作为模型系统，研究者观察到两种具有截然不同各向异性的氧振动：低于60 meV的扁球状热椭球体和高于60 meV的长球状热椭球体。

在非中心对称的钛酸钡中，他们的方法通过观察在55 meV附近顶端和赤道氧位点之间q选择性信号的意外调制，能够检测氧八面体的细微畸变，这源于晶体对称性的降低，并可能与铁电极化有关。

这些观察结果得到了理论模型的定量支持，证明了改方法的可靠性。测量到的频率依赖的振动各向异性为声学声子和光学声子主导的介电和热行为提供了新的见解。以前所未有的空间和能量分辨率，在特定晶体学位点可视化声子本征矢量的能力，为探索介电、光学、热学和超导性质开辟了新途径。

▲ Abstract：

Directly visualizing vibrational anisotropy in individual phonon modes is essential for understanding a wide range of intriguing optical, thermal and elastic phenomena in materials. Although conventional optical and diffraction techniques have been used to estimate vibrational anisotropies, they fall short in achieving the spatial and energy resolution necessary to provide detailed information. Here, we introduce a new form of momentum-selective electron energy-loss spectroscopy, which enables the element-resolved imaging of frequency- and symmetry-dependent vibrational anisotropies with atomic resolution. Vibrational anisotropies manifest in different norms of orthogonal atomic displacements, known as thermal ellipsoids. Using the centrosymmetric strontium titanate as a model system, we observed two distinct types of oxygen vibrations with contrasting anisotropies: oblate thermal ellipsoids below 60?meV and prolate ones above 60?meV. In non-centrosymmetric barium titanate, our approach can detect subtle distortions of the oxygen octahedra by observing the unexpected modulation of q-selective signals between apical and equatorial oxygen sites near 55?meV, which originates from reduced crystal symmetry and may also be linked to ferroelectric polarization. These observations are quantitatively supported by theoretical modelling, which demonstrates the reliability of our approach. The measured frequency-dependent vibrational anisotropies shed new light on the dielectric and thermal behaviours governed by acoustic and optical phonons. The ability to visualize phonon eigenvectors at specific crystallographic sites with unprecedented spatial and energy resolution opens new avenues for exploring dielectric, optical, thermal and superconducting properties.

化学Chemistry

Robot-assisted mapping of chemical reaction hyperspaces and networks

机器人辅助的化学反应超空间与网络图谱构建

▲ 作者：Yankai Jia, Rafa? Frydrych, Yaroslav I. Sobolev, Wai-Shing Wong, Bibek Prajapati, Daniel Matuszczyk, Yasemin Bilgi, Louis Gadina, Juan Carlos Ahumada, Galymzhan Moldagulov, Namhun Kim, Eric S. Larsen, Maxence Deschamps, Yanqiu Jiang & Bartosz A. Grzybowski

▲链接：

https://www.nature.com/articles/s41586-025-09490-1

▲摘要：

尽管经过数十年的研究，化学反应的产物如何随反应条件所定义的多维'超空间'而变化，仍然不清楚且难以预测。研究者开发了一种低成本机器人平台，主要利用光学检测以前所未有的通量和每个条件最低的成本来定量产物和副产物的产率。

通过对数千种条件进行超空间扫描，研究者发现并在数学上证明，对于连续变量（浓度、温度），单个产率分布通常是缓慢变化的。同时，研究揭示了具有意外反应活性的超空间区域以及主要产物之间的转换点。

此外，通过系统性地考察底物比例，研究者重建了潜在的反应网络，并揭示了隐藏的中间体和产物——即使是在已经被研究了一个多世纪的反应中也是如此。

这种超空间扫描方法为反应优化和发现提供了一个多功能且可扩展的框架。关键的是，它有助于识别在何种条件下可以将复杂混合物清晰地导向不同的主要产物，从而在减少化学试剂投入的同时扩展合成多样性。

▲ Abstract：

Despite decades of investigation, it remains unclear (and hard to predict) how the outcomes of chemical reactions change over multidimensional ‘hyperspaces’ defined by reaction conditions. Here, to address these questions, we developed a low-cost robotic platform using primarily optical detection to quantify yields of products and by-products at unprecedented throughput and minimal cost per condition. Scanning hyperspaces across thousands of conditions, we find and prove mathematically that, for continuous variables (concentrations, temperatures), individual yield distributions are generally slow-varying. At the same time, we uncover hyperspace regions of unexpected reactivity as well as switchovers between major products. Moreover, by systematically surveying substrate proportions, we reconstruct underlying reaction networks and expose hidden intermediates and products—even in reactions studied for well over a century. This hyperspace-scanning approach provides a versatile and scalable framework for reaction optimization and discovery. Crucially, it can help identify conditions under which complex mixtures can be driven cleanly towards different major products, thereby expanding synthetic diversity while reducing chemical input requirements.

Catalytic enantioselective synthesis of alkylidenecyclopropanes

催化对映选择性合成亚烷基环丙烷

▲ 作者：Jonathan C. Golec, Dong-Hang Tan, Ken Yamazaki, Eveline H. Tiekink, Kirsten E. Christensen, Trevor A. Hamlin & Darren J. Dixon

▲链接：

https://www.nature.com/articles/s41586-025-09485-y

▲摘要：

小环碳环的对映选择性构建是有机化学家面临的一项长期挑战。尽管具有商业重要性，但针对亚烷基环丙烷（一类小环碳环）的对映选择性合成路线仍然开发不足。亚烷基环丙烷可以转化为环丙烷，后者是药物分子以及天然和合成农化产品中的常见结构单元。

研究者描述了一种通过使用双功能亚氨基磷烷催化、立体控制的应变释放去共轭反应，来简便合成高对映体富集的亚烷基环丙烷的方法。通过对基础催化剂体系进行微小修饰，扩大了该反应的适用范围，使其可用于含有酯、酰胺、氧化膦和酮官能团的底物。

通过设计合适的底物并重新调控催化剂的亚氨基磷烷部分，该转化被有效地应用于合成常见杀虫剂氯菊酯的单一立体异构体，以及一系列基于环丙烷的杀虫剂核心结构。研究者通过开展最先进的计算研究，深入揭示了其反应机理路径以及非对映选择性和对映选择性的起源。

▲ Abstract：

The enantioselective construction of small-ring carbocycles provides organic chemists with an enduring challenge. Despite their commercial importance, enantioselective synthetic routes towards alkylidenecyclopropanes, a class of small-ring carbocycles, remain underdeveloped. Alkylidenecyclopropanes can be converted into cyclopropanes, a common feature in drug molecules, as well as both naturally occurring and synthetic agrochemicals. Here we describe the facile synthesis of highly enantioenriched alkylidenecyclopropanes through the use of a bifunctional iminophosphorane catalysed, stereo-controlled, strain-relieving deconjugation. Small modifications to the basic catalyst system were used to broaden the scope of the reaction to substrates containing ester, amide, phosphine oxide and ketone functionalities. Through the design of a suitable substrate and retuning of the catalyst’s iminophosphorane moiety, the transformation was effectively applied to the synthesis of a single stereoisomer of the commonplace insecticide permethrin as well as a range of cyclopropane-based insecticide cores. State-of-the-art computational studies were performed to provide detailed insights into the mechanistic pathway and origin of both diastereoselectivities and enantioselectivities.

生态学Ecology

Stronger El Ni?os reduce tropical forest arthropod diversity and function

更强厄尔尼诺降低热带森林节肢动物多样性与生态功能

▲ 作者：Adam C. Sharp, Michael J. W. Boyle, Timothy C. Bonebrake, Yirong Guo, Roger L. Kitching, Nigel E. Stork, Xiaoyi Zeng & Louise A. Ashton

▲链接：

https://www.nature.com/articles/s41586-025-09351-x

▲摘要：

目前，关于节肢动物对气候变化的脆弱性仍存在争议。气候变化对节肢动物群落的长期影响，可能会通过短期天气模式显现。热带地区的节肢动物具有极高的多样性，且承担着众多关键生态系统功能，但相较于温带地区的节肢动物，对其的研究仍较为匮乏。在气候变化背景下，热带森林节肢动物及其所提供的生态功能，可能易受加剧的厄尔尼诺现象威胁。

研究者对原始热带森林的相关数据进行了时间序列分析，结果表明：节肢动物多样性与生态功能的长期下降，与厄尔尼诺现象的发生存在关联。在美洲地区，物种减少与物种对厄尔尼诺的敏感性相关，而优势物种的数量波动则取决于其摄食特征与生态特化程度。东南亚地区蝴蝶种群数量的同步下降，表明这种影响已跨越大陆。

预测的节肢动物多样性变化，与观测到的无脊椎动物介导的分解作用速率及叶片取食（植食）作用速率存在相关性——在全球热带地区，前者呈现波动趋势，后者则出现显著下降。

分析表明，加剧的厄尔尼诺现象正直接威胁热带森林节肢动物及其提供的生态系统功能。其更广泛的影响尚不明晰，但此类大范围变化可能从根本上改变热带森林生态系统。

研究者表示，在全球热带地区开展节肢动物多样性与森林生态功能的长期监测至关重要，同时，研究这一新型威胁背后的潜在机制也同样紧迫。

▲ Abstract：

There is ongoing debate about the vulnerability of arthropods to climate change. Long-term impacts of climate change on arthropod communities could manifest through short-term weather patterns. Arthropods in the tropics are hyper-diverse and contribute many crucial ecosystem functions, but are comparatively less studied than in temperate regions. Tropical forest arthropods and the functions that they provide may be vulnerable to intensified El Ni?o events under climate change. Here we perform time-series analysis of data from primary tropical forests, which reveal long-term declines in arthropod diversity and function that were linked to El Ni?o occurrence. In the Americas, species losses correlated with El Ni?o sensitivity, and abundant species fluctuated according to feeding traits and level of ecological specialization. Parallel declines in butterflies in Southeast Asia suggested that impacts spanned continents. Predicted arthropod diversity changes correlated with observed rates of invertebrate-mediated decomposition and leaf herbivory, which were oscillating and crashing, respectively, across the tropics. Our analyses suggest that an intensified El Ni?o immediately threatens tropical forest arthropods and the ecosystem functions that they provide. The broader consequences remain unknown, but such widespread changes could fundamentally alter tropical forest ecosystems. Long-term monitoring of arthropod diversity and forest functioning across the tropics is paramount, as is researching the potential mechanisms that underly this novel threat.

生物学Biology

Replay and representation dynamics in the hippocampus of freely flying bats

自由飞行蝙蝠海马体中的重放与表征动力学

▲ 作者：Angelo Forli, Wudi Fan, Kevin K. Qi & Michael M. Yartsev

▲链接：

https://www.nature.com/articles/s41586-025-09341-z

▲摘要：

导航和记忆的认知功能依赖于海马体中神经集群的涌现特性。然而，这些现象是否以及如何在具有不同导航需求和神经生理特性的物种间普适存在，仍然不清楚。

研究通过无线记录技术，在从事自由、自发觅食行为的埃及果蝠海马体中，记录了大规模细胞群的神经活动以及局部场电位。研究者识别出在休息期间，与尖波涟漪同时发生的、多个飞行轨迹的时间压缩式正向和反向重放。值得注意的是，重放主要发生在与所重放行为在空间和时间上都相距遥远的位置，并且其速度与轨迹长度成比例，这对现有的重放机制模型提出了挑战。

在飞行过程中，神经集群表现出快速的特征“扫描”，即解码出的位置周期性地移动到蝙蝠实际位置的前方。与啮齿类动物中的报道相反，这些扫描活动是在没有theta振荡的情况下发生的，而是与一个显著的运动行为节律——蝙蝠的翅膀拍打周期——相位锁定。这表明行为相关的感觉运动节律能够以高度结构化的方式与海马体集群动力学相互作用。

综上所述，这一发现对现有哺乳动物海马体集群动力学模型提出了挑战，并强调了在行为学相关条件下进行比较研究对于阐明脑功能的重要性。

▲ Abstract：

Cognitive functions for navigation and memory rely on emergent properties of neural ensembles in the hippocampus, such as activity replay and theta sequences. However, whether and how these phenomena generalize across species with distinct navigational demands and neurophysiological properties remains unclear. Here we wirelessly recorded neural activity from large populations of cells and local field potentials from the hippocampus of freely flying Egyptian fruit bats (Rousettus aegyptiacus) engaged in free, spontaneous foraging behaviour. During rest, we identified time-compressed forward and reverse replays of multiple flight trajectories coinciding with sharp-wave ripples. Notably, replays occurred predominantly at locations that were both spatially and temporally distant from the replayed behaviour, and their speed scaled with trajectory length, challenging present models of replay mechanisms. During flight, neural ensembles exhibited fast representational sweeps, in which the decoded location moved ahead of the bat’s position cyclically. In contrast to reports in rodents, sweeps occurred in the absence of theta oscillations, and were instead phase locked to a prominent motor behavioural rhythm—the bat’s wing-beat cycle. This suggests that behaviourally relevant sensorimotor rhythms can interact with hippocampal ensemble dynamics in a highly structured manner. Combined, our findings challenge existing models of ensemble dynamics in the mammalian hippocampus, and highlight the importance of comparative studies in ethologically relevant conditions for elucidating brain function.

(責任編輯：探索)