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%91200%20foot%20crane 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
Controlling spin currents,学网WhatsApp%E3%80%90+86%2015855158769%E3%80%91200%20foot%20crane 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
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
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
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
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
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.
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