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《自然》（20240919出版）一周论文导读

编译 | 李言

Nature,19 September 2024, Volume 633 Issue 8030

《自然》，2024年9月19日，第633卷，8030期

化学Chemistry

Growth of complete ammonia oxidizers on guanidine

完全氨氧化剂在胍上的生长

▲ 作者：Marton Palatinszky, Craig W. Herbold et al.

▲ 链接：

https://www.nature.com/articles/s41586-024-07832-z

▲ 摘要：

在此，我们证明了完全氨氧化剂硝化螺旋菌和大多数其他comammox微生物可以以胍为唯一的能量、还原剂和氮源生长。蛋白质组学、酶动力学和晶体结构的研究表明，它是一种真正的胍酶。含comammox的农业土壤和污水处理厂微生物组的培养实验表明，胍是环境中硝化作用的底物。胍作为comammox生长底物的鉴定显示了这些全球重要硝化菌的出乎意料的生态位，并为它们的分离提供了机会。

▲ Abstract：

Here we show that the complete ammonia oxidizer (comammox) Nitrospira inopinata and probably most other comammox microorganisms can grow on guanidine as the sole source of energy, reductant and nitrogen. Proteomics, enzyme kinetics and the crystal structure of a N. inopinata guanidinase homologue demonstrated that it is a bona fide guanidinase. Incubation experiments with comammox-containing agricultural soil and wastewater treatment plant microbiomes suggested that guanidine serves as substrate for nitrification in the environment. The identification of guanidine as a growth substrate for comammox shows an unexpected niche of these globally important nitrifiers and offers opportunities for their isolation.

物理学Physics

Dynamic transition and Galilean relativity of current-driven skyrmions

电流驱动斯格明子的动态跃迁和伽利略相对性

▲ 作者：Max T. Birch, Ilya Belopolski et al.

▲ 链接：

https://www.nature.com/articles/s41586-024-07859-2

▲ 摘要：

在这里，我们报告了Gd2PdSi3中由其显著的拓扑霍尔效应（THE）所促进的斯格明子晶格（SkL）运动引发的新兴电动力学现象。随着电流激励的增加，我们观察到SkL运动从钉住状态到蠕变状态，最后到流动状态的动态转变，其中THE完全被抑制。

我们认为，即使在如目前的化合物的复杂多带系统中，也可以在流动状态中恢复完全抵消所需要的伽利略相对性。此外，我们观察到的电压足够大，可以实时测量SkL的速度—电流曲线。该曲线显示SkL在蠕变状态下的惯性运动，表现为斯格明子速度的电流滞后现象。

▲ Abstract：

Here we report the emergent electrodynamics induced by SkL motion in Gd2PdSi3, facilitated by its giant THE. With increasing current excitation, we observe the dynamic transition of the SkL motion from the pinned to creep regime and finally to the flow regime, in which the THE is totally suppressed. We argue that the Galilean relativity required for the total cancellation of the THE may be generically recovered in the flow regime, even in complex multiband systems such as the present compound. Moreover, the observed THE voltages are large enough to enable real-time measurement of the SkL velocity–current profile, which shows the inertial-like motion of the SkL in the creep regime, appearing as the current hysteresis of the skyrmion velocity.

医学Medicine

Frontostriatal salience network expansion in individuals in depression

抑郁症患者的额纹状体显著网络扩展

▲ 作者：Charles J. Lynch, Immanuel G. Elbau et al.

▲ 链接：

https://www.nature.com/articles/s41586-024-07805-2

▲ 摘要：

在此，使用精确的函数映射和几个深度采样的个体样本，我们发现大多数抑郁症患者的额纹状体显著性网络在皮质中扩展了近两倍。这种效应在几个样本中是可复制的，主要是由网络边界移动引起的，在不同的个体中发生了三种不同的入侵模式。

随着时间的推移，显著性网络扩展是稳定的，不受情绪状态的影响，在青春期后期抑郁发作前的儿童中可以检测到。在1.5年的时间里，我们对患者进行了多达62次的纵向分析，发现了额纹状体回路的连通性变化，追踪了特定症状的波动，并预测了未来的快感缺乏症状。

总之，这些发现确定了一种特征样的大脑网络拓扑结构。它可能带来抑郁症的风险，以及额纹状体回路中情绪状态依赖性连接的变化，这些变化可以预测抑郁症状随时间的出现和缓解。

▲ Abstract：

Here, using precision functional mapping and several samples of deeply sampled individuals, we found that the frontostriatal salience network is expanded nearly twofold in the cortex of most individuals with depression. This effect was replicable in several samples and caused primarily by network border shifts, with three distinct modes of encroachment occurring in different individuals. Salience network expansion was stable over time, unaffected by mood state and detectable in children before the onset of depression later in adolescence. Longitudinal analyses of individuals scanned up to 62 times over 1.5 years identified connectivity changes in frontostriatal circuits that tracked fluctuations in specific symptoms and predicted future anhedonia symptoms. Together, these findings identify a trait-like brain network topology that may confer risk for depression and mood-state-dependent connectivity changes in frontostriatal circuits that predict the emergence and remission of depressive symptoms over time.

地球科学Earth Science

Decoding drivers of carbon flux attenuation in the oceanic biological pump

解码海洋生物泵中碳通量衰减的驱动因素

▲ 作者：M. Bressac, E. C. Laurenceau-Cornec et al.

▲ 链接：

https://www.nature.com/articles/s41586-024-07850-x

▲ 摘要：

在此，我们展示了C-RESPIRE的原位实验结果。C-RESPIRE是一种部署在多个中层深度的双粒子和培养箱，用于测量微生物介导的颗粒有机碳（POC）通量衰减。

我们发现，在6个不同的海洋体系中，即POC通量的30倍范围内，颗粒附着微生物的降解为通量衰减的7%—29%，这意味着浮游动物在通量衰减中发挥了更大的影响作用。微生物再矿化，标准化到POC通量，在不同的地点和深度范围20倍，在高POC通量下速率最低。

高达三倍变化的垂直趋势与低纬度地区强烈的温度梯度有关。与之相反，在中高纬度地区，温度的影响较小，而垂直趋势可能由颗粒生物化学、破碎化和微生物生态生理共同决定。马丁曲线的解构揭示了驱动微生物介导的POC通量衰减的基本机制。

▲ Abstract：

Here we present in situ experimental findings from C-RESPIRE, a dual particle interceptor and incubator deployed at multiple mesopelagic depths, measuring microbially mediated POC flux attenuation. We find that across six contrasting oceanic regimes, representing a 30-fold range in POC flux, degradation by particle-attached microbes comprised 7–29 per cent of flux attenuation, implying a more influential role for zooplankton in flux attenuation. Microbial remineralization, normalized to POC flux, ranged by 20-fold across sites and depths, with the lowest rates at high POC fluxes. Vertical trends, of up to threefold changes, were linked to strong temperature gradients at low-latitude sites. In contrast, temperature played a lesser role at mid- and high-latitude sites, where vertical trends may be set jointly by particle biochemistry, fragmentation and microbial ecophysiology. This deconstruction of the Martin curve reveals the underpinning mechanisms that drive microbially mediated POC flux attenuation across oceanic provinces.

Observation-constrained projections reveal longer-than-expected dry spells

预测显示干旱期将长于预期

▲ 作者：Irina Y. Petrova, Diego G. Miralles et al.

▲ 链接：

https://www.nature.com/articles/s41586-024-07887-y

▲ 摘要：

在此，我们表明使用新提出的紧急约束（EC）来约束模型预测，可以在全球范围内将核心干旱指标——最长年度干旱期（LAD）——预测的不确定性降低10%—26%。经EC校正后的预测结果显示，与目前预测的未来作用力情景相比，LAD的平均增幅将高出42%—44%。这些结果表明，到本世纪末，全球平均仅陆地的LAD可能比目前预计的要长10天。

利用两代气候模式，我们进一步揭示了历史LAD偏差影响预估LAD增加幅度的全球区域，并探讨了陆地—大气反馈在其中的作用。我们的研究结果揭示了一些地区的社会和生态系统可能面临比预期更高、更早的干旱风险，并指出了当前一代气候模型中存在偏差的可能机制。

▲ Abstract：

Here we show that constraining model projections with observations using a newly proposed emergent constraint (EC) reduces the uncertainty in predictions of a core drought indicator, the longest annual dry spell (LAD), by 10–26% globally. Our EC-corrected projections reveal that the increase in LAD will be 42–44% greater, on average, than ‘mid-range’ or ‘high-end’ future forcing scenarios currently indicate. These results imply that by the end of this century, the global mean land-only LAD could be 10 days longer than currently expected. Using two generations of climate models, we further uncover global regions for which historical LAD biases affect the magnitude of projected LAD increases, and we explore the role of land–atmosphere feedbacks therein. Our findings reveal regions with potentially higher- and earlier-than-expected drought risks for societies and ecosystems, and they point to possible mechanisms underlying the biases in the current generation of climate models.

A climate threshold for ocean deoxygenation during the Early Cretaceous

白垩纪早期海洋脱氧的气候阈值

▲ 作者：Kohen W. Bauer, N. Ryan McKenzie et al.

▲ 链接：

https://www.nature.com/articles/s41586-024-07876-1

▲ 摘要：

在此，我们的研究显示，在白垩纪大洋缺氧事件（OAE1a）期间海洋快速脱氧与火山二氧化碳排放和相关气候阈值的跨越有关。此后，硅酸盐风化反馈和气候恢复的缓慢步伐将再氧化的延迟事件大于1百万年。在OAE1a结束时，重新越过这个阈值并使得海洋再氧化。

然而，在OAE1a之后，地球系统保持足够的温暖，以至于轨道驱动的气候动力学导致海洋在大约10亿年的时间尺度上继续循环脱氧，并持续了1百万年。因此，我们的结果暗示了火山作用、风化作用和海洋氧含量之间的紧密耦合，这种耦合以气候阈值为特征。

▲ Abstract：

Here we show that rapid ocean deoxygenation during OAE1a is linked to volcanic CO2 emissions and the crossing of an associated climate threshold, after which the sluggish pace of the silicate-weathering feedback and climate recovery delayed reoxygenation for >1 Myr. At the end of OAE1a, recrossing this threshold allowed for ocean reoxygenation. Following OAE1a, however, the Earth system remained sufficiently warm such that orbitally forced climate dynamics led to continued cyclic ocean deoxygenation on approximately 100-kyr timescales for another 1 Myr. Our results thus imply a tight coupling between volcanism, weathering and ocean oxygen content that is characterized by a climate threshold.

《自然》（20241114出版）一周论文导读

编译 | 李言

Nature, 14 November 2024, Volume 635 Issue 8038

《自然》2024年11月14日，第635卷，8038期

大自然(Nature);大自然的声音

天文学Astronomy

Accelerated formation of ultra-massive galaxies in the first billion years

最初10亿年超大质量星系的加速形成

▲ 作者：Mengyuan Xiao, Pascal A. Oesch et al.

▲ 链接：

https://www.nature.com/articles/s41586-024-08094-5

▲ 摘要：

在此，我们报告对JWST FRESCO调查中的36个大质量尘埃遮蔽星系的系统研究，这些星系的光谱红移在5到9之间。在样本中，我们没有发现Λ 冷暗物质模型具有张力。

然而，三个超大质量星系（logM/M⊙ ≳ 11.0，其中M为恒星质量，M⊙为太阳质量）需要50%的重子转化为恒星——比后期最有效的星系高2到3倍。这不太可能是因为活动星系核，因为它们的辐射范围很广。在大约5到6的红移范围内，超大质量星系占宇宙恒星形成率密度的17%。

▲ Abstract：

Here we report a systematic study of 36 massive dust-obscured galaxies with spectroscopic redshifts between 5 and 9 from the JWST FRESCO survey. We find no tension with the Λ cold dark-matter model in our sample. However, three ultra-massive galaxies (logM/M⊙ ≳ 11.0, whereM is the stellar mass and M⊙ is the mass of the Sun) require an exceptional fraction of 50 per cent of baryons converted into stars—two to three times higher than the most efficient galaxies at later epochs. The contribution from an active galactic nucleus is unlikely because of their extended emission. Ultra-massive galaxies account for as much as 17 per cent of the total cosmic star-formation-rate density at redshifts between about five and six.

物理学Physics

Observation of vortices in a dipolar supersolid

偶极超固体中涡旋的观测

▲ 作者：Eva Casotti, Elena Poli et al.

▲ 链接：

https://www.nature.com/articles/s41586-024-08149-7

▲ 摘要：

在此，掌握了在偶极气体和具有二维结晶顺序的超固体中产生涡旋的方法后，我们报告了超固体相（SSP）中涡旋的理论研究和实验观察。我们的工作揭示了未调制和调制量子流体之间涡旋形成动力学的根本差异。

这为研究具有许多存在于不同领域——如量子晶体和中子星发——中的自对称性破缺的奇异量子系统的流体动力学特性打开了大门。

▲ Abstract：

Here, with the prerequisite pieces at our disposal, namely a method to generate vortices in dipolar gases and supersolids with two-dimensional crystalline order, we report on the theoretical investigation and experimental observation of vortices in the supersolid phase (SSP). Our work reveals a fundamental difference in vortex seeding dynamics between unmodulated and modulated quantum fluids. This opens the door to study the hydrodynamic properties of exotic quantum systems with numerous spontaneously broken symmetries, in disparate domains such as quantum crystals and neutron stars.

Phonon modes and electron–phonon coupling at the FeSe/SrTiO3interface

FeSe/SrTiO3界面处的声子模式和电子—声子耦合

▲ 作者：Hongbin Yang, Yinong Zhou et al.

▲ 链接：

https://www.nature.com/articles/s41586-024-08118-0

▲ 摘要：

在此，我们使用动量选择高分辨率电子能量损失谱，在原子尺度上解析FeSe/STO界面上的声子。我们在75—99 meV的能量范围内发现了新的光学声子模式，与电子强耦合。这些模式的特征是界面双层TiOx层中的氧原子和STO中的顶端氧原子的面外振动。

我们的结果还表明，1 uc FeSe/STO的EPC强度和超导间隙与FeSe与TiOx端接STO之间的层间距密切相关。这些发现揭示了界面EPC的微观起源，并为在FeSe/STO和潜在的其他超导系统中实现大规模和稳定的Tc增强提供了见解。

▲ Abstract：

Here we use momentum-selective high-resolution electron energy loss spectroscopy to atomically resolve the phonons at the FeSe/STO interface. We uncover new optical phonon modes, coupling strongly with electrons, in the energy range of 75–99 meV. These modes are characterized by out-of-plane vibrations of oxygen atoms in the interfacial double-TiOx layer and the apical oxygens in STO. Our results also demonstrate that the EPC strength and superconducting gap of 1 uc FeSe/STO are closely related to the interlayer spacing between FeSe and the TiOx terminated STO. These findings shed light on the microscopic origin of the interfacial EPC and provide insights into achieving large and consistent Tc enhancement in FeSe/STO and potentially other superconducting systems.

地球科学Earth Science

Mapping the ionosphere with millions of phones

百万部手机绘制电离层“地图”

▲ 作者：Jamie Smith, Anton Kast et al.

▲ 链接：

https://www.nature.com/articles/s41586-024-08072-x

▲ 摘要：

在此，我们展示了一个由噪声传感器组成的分布式网络——以数百万部安卓手机的形式——可以填补许多这些空白，并将测量覆盖范围扩大一倍，在世界上传统基础设施服务不足的地区提供电离层的准确图像。

通过智能手机测量，我们分析了印度和南美上空的等离子体气泡、北美上空太阳风暴增强的密度以及欧洲上空的中纬度电离层槽等特征。我们还表明，由此产生的电离层“地图”可以提高定位精度，这是我们的主要目标。

这项研究展示了使用大型分布式智能手机网络作为监测地球的强大科学仪器的潜力。

▲ Abstract：

Here we demonstrate that a distributed network of noisy sensors—in the form of millions of Android phones—can fill in many of these gaps and double the measurement coverage, providing an accurate picture of the ionosphere in areas of the world underserved by conventional infrastructure. Using smartphone measurements, we resolve features such as plasma bubbles over India and South America, solar-storm-enhanced density over North America and a mid-latitude ionospheric trough over Europe. We also show that the resulting ionosphere maps can improve location accuracy, which is our primary aim. This work demonstrates the potential of using a large distributed network of smartphones as a powerful scientific instrument for monitoring Earth.

High CO2dampens then amplifies N-induced diversity loss over 24 years

24年来，高二氧化碳浓度的抑制放大了氮引起的多样性损失

▲ 作者：Peter B. Reich, Neha Mohanbabu et al.

▲ 链接：

https://www.nature.com/articles/s41586-024-08066-9

▲ 摘要：

氮沉降导致了全球局部生物多样性的损失，但二氧化碳浓度的上升是否会加剧或抑制损失情况，以及如何加剧或抑制这些损失，目前尚不清楚，而且几乎完全没有研究过。

通过一个露天实验，我们回答了这一认知空缺。露天实验中，108块草地在不同的二氧化碳和氮水平下生长了24年。我们初步发现，增加氮对植物物种丰富度的降低在二氧化碳浓度升高的情况下比在二氧化碳浓度升高的情况下要小。

然而，随着时间的推移，这种相互作用发生了逆转，二氧化碳浓度的升高放大了富氮导致的多样性损失，在过去8年的研究中，氮添加导致的物种丰富度减少了三倍。

这些相互作用源于多样性驱动因素的时间变化，尤其是光有效性，而光有效性又由二氧化碳和氮输入以及植物生物量的相关变化驱动。这一机制在许多草地上可能是相似的，因为植物资源中二氧化碳和氮的添加可能会增加优势物种的丰度。

如果二氧化碳的上升普遍加剧了氮沉降对植物多样性的广泛负面影响，这对全球草地生物多样性的保护来说是一个不好的兆头。

▲ Abstract：

Nitrogen deposition causes local biodiversity loss globally, but whether, and if so how, rising CO2concentrations amplify or dampen those losses remains unclear and is almost entirely unstudied. We addressed this knowledge gap with an open-air experiment in which 108 grassland plots were grown for 24 years under different CO2 and N regimes. We initially found that adding N reduced plant species richness less at elevated than at ambient CO2. Over time, however, this interaction reversed, and elevated CO2 amplified losses in diversity from enriched N, tripling reductions in species richness from N addition over the last eight years of the study. These interactions resulted from temporal changes in the drivers of diversity, especially light availability, that were in turn driven by CO2 and N inputs and associated changes in plant biomass. This mechanism is likely to be similar in many grasslands, because additions of the plant resources CO2 and N are likely to increase the abundance of the dominant species. If rising CO2 generally exacerbates the widespread negative impacts of N deposition on plant diversity, this bodes poorly for the conservation of grassland biodiversity worldwide.

生物学Biology

Inducing novel endosymbioses by implanting bacteria in fungi

通过在真菌中植入细菌诱导新的内共生

▲ 作者：Gabriel H. Giger, Chantal Ernst et al.

▲ 链接：

https://www.nature.com/articles/s41586-024-08010-x

▲ 摘要：

在此，我们将细菌植入丝状真菌小孢根霉，进行人工诱导的内共生。大肠杆菌植入细胞质后可诱导隔膜形成，有效阻止内共生，而根瘤菌则以低频率垂直传播给后代。

在适应进化过程中，内共生的持续正向选择将初始适应度约束降低了几个数量级。随着系统的稳定，宿主中突变的积累强调了表型变化。该细菌在其新宿主体内产生了根毒素同系物，证明了通过诱导内共生的代谢功能的转移。

因此，单细胞植入提供了一种强大的实验方法来研究内共生发生开始时的关键事件，并为设计具有所需性状的内共生的综合方法提供了机会。

▲ Abstract：

Here we implant bacteria into the filamentous fungus Rhizopus microsporus to follow the fate of artificially induced endosymbioses. Whereas Escherichia coli implanted into the cytosol induced septum formation, effectively halting endosymbiogenesis, Mycetohabitans rhizoxinica was transmitted vertically to the progeny at a low frequency. Continuous positive selection on endosymbiosis mitigated initial fitness constraints by several orders of magnitude upon adaptive evolution. Phenotypic changes were underscored by the accumulation of mutations in the host as the system stabilized. The bacterium produced rhizoxin congeners in its new host, demonstrating the transfer of a metabolic function through induced endosymbiosis. Single-cell implantation thus provides a powerful experimental approach to study critical events at the onset of endosymbiogenesis and opens opportunities for synthetic approaches towards designing endosymbioses with desired traits.

《自然》（20241024出版）一周论文导读

编译 | 冯维维

Nature, Volume 634 Issue 8035, 24 October 2024

大自然(Nature);大自然的声音

《自然》,第634卷，8035期，2024年10月24日

物理学Physics

Two waves of massive stars running away from the young cluster R136

两波大质量恒星正从年轻的星团R136中逃逸

▲ 作者：Mitchel Stoop, Alex de Koter, Lex Kaper, Sarah Brands, Simon Portegies Zwart, Hugues Sana, Fiorenzo Stoppa, Mark Gieles, Laurent Mahy, Tomer Shenar, Difeng Guo, Gijs Nelemans & Steven Rieder

▲ 链接：

https://www.nature.com/articles/s41586-024-08013-8

▲ 摘要：

大质量恒星主要在星团或星协中形成的。它们的辐射场、恒星风和超新星强烈地影响着当地的环境。在星团生命的最初几百万年里，大质量恒星被动态地喷射出来，并以高速逃离星团。然而，动态弹射脱轨的产率约束较差。

研究者报告了从大麦哲伦星云的年轻星团R136中喷射出的55颗大质量逃逸恒星的样本。对盖亚数据的天体测量学分析揭示了两个动态弹出的逃逸通道。第一个通道向各个方向喷射大质量恒星，与R136诞生期间和之后的动力学相互作用一致。第二个通道以首选方向发射恒星，可能与星团相互作用有关。

他们发现，最初诞生于R136的最亮恒星中，有23%~33%是逃逸恒星。模型预测明显低估了大质量恒星的动态逃逸率。因此，它们在塑造和加热星际和星系介质中的作用，以及它们在驱动星系外流中的作用，比以前想象的要重要得多。

▲ Abstract：

Massive stars are predominantly born in stellar associations or clusters. Their radiation fields, stellar winds and supernovae strongly impact their local environment. In the first few million years of a cluster’s life, massive stars are dynamically ejected and run away from the cluster at high speed. However, the production rate of dynamically ejected runaways is poorly constrained. Here we report on a sample of 55 massive runaway stars ejected from the young cluster R136 in the Large Magellanic Cloud. An astrometric analysis of Gaia data reveals two channels of dynamically ejected runaways. The first channel ejects massive stars in all directions and is consistent with dynamical interactions during and after the birth of R136. The second channel launches stars in a preferred direction and may be related to a cluster interaction. We found that 23–33% of the most luminous stars initially born in R136 are runaways. Model predictionshave significantly underestimated the dynamical escape fraction of massive stars. Consequently, their role in shaping and heating the interstellar and galactic media and their role in driving galactic outflows are far more important than previously thought.

Harnessing plasticity in sequential metamaterials for ideal shock absorption

利用序贯超材料的塑性实现理想的减震

▲ 作者：Wenfeng Liu, Shahram Janbaz, David Dykstra, Bernard Ennis & Corentin Coulais

▲ 链接：

https://www.nature.com/articles/s41586-024-08037-0

▲ 摘要：

机械超材料表现出低密度下的高刚度、增强的能量吸收、形状变形、顺序变形、互动性和鲁棒波导等有趣的特性。到目前为止，超材料设计主要依赖于几何，材料的非线性，如粘弹性、断裂和塑性，在很大程度上被排除在设计原理之外。事实上，塑性变形传统上被视为一种失效模式，因此被小心地避免。

在这里，研究者拥抱塑性，而不是发现塑性和屈曲不稳定性之间的微妙平衡，并将其称之为“获得屈曲”。他们利用“获得屈曲”来设计在任意大的步骤序列中依次屈曲的超材料，同时保持承载能力，并利用连续屈服屈曲来制造结合了刚度和耗散的超材料。这两种特性通常是不相容的，而且可以多次使用。

这种高超材料表现出优异的减震性能。研究者表示，该发现为超材料工具箱增加了可塑性，使机械超材料成为一项具有大规模生产潜力的新兴技术。

▲ Abstract：

Mechanical metamaterials exhibit interesting properties such as high stiffness at low density, enhanced energy absorption, shape morphing, sequential deformations, auxeticity and robust waveguiding. Until now, metamaterial design has primarily relied on geometry, and materials nonlinearities such as viscoelasticity, fracture and plasticity have been largely left out of the design rationale. In fact, plastic deformations have been traditionally seen as a failure mode and thereby carefully avoided. Here we embrace plasticity instead and discover a delicate balance between plasticity and buckling instability, which we term ‘yield buckling’. We exploit yield buckling to design metamaterials that buckle sequentially in an arbitrary large sequence of steps whilst keeping a load-bearing capacity. We make use of sequential yield buckling to create metamaterials that combine stiffness and dissipation—two properties that are usually incompatible—and that can be used several times. Hence, our metamaterials exhibit superior shock-absorption performance. Our findings add plasticity to the metamaterial toolbox and make mechanical metamaterials a burgeoning technology with serious potential for mass production.

Quasi-periodic X-ray eruptions years after a nearby tidal disruption event

准周期性的x射线喷发，发生在附近的潮汐破坏事件数年后

▲ 作者：M. Nicholl, D. R. Pasham, A. Mummery, M. Guolo, K. Gendreau, G. C. Dewangan, E. C. Ferrara, R. Remillard, C. Bonnerot, J. Chakraborty, A. Hajela, V. S. Dhillon, A. F. Gillan, J. Greenwood, M. E. Huber, A. Janiuk, G. Salvesen, S. van Velzen, A. Aamer, K. D. Alexander, C. R. Angus, Z. Arzoumanian, K. Auchettl, E. Berger, …D. R. Young

▲ 链接：

https://www.nature.com/articles/s41586-024-08023-6

▲ 摘要：

准周期爆发（QPEs）是来自星系核心的软X射线的发光爆发，在数小时到数周的时间尺度上重复。这些罕见系统背后的机制尚不确定，但大多数理论都涉及超大质量黑洞（SMBHs）周围的吸积盘经历不稳定或与近轨道上的恒星物体相互作用。

有人提出，当SMBH破坏一颗路过的恒星时，可能会形成这个圆盘，这意味着许多QPE应该在可观测到的潮汐破坏事件（TDEs）之前发生。两个已知的QPE源显示出与TDE一致的静态光度的长期衰减，两个观测到的TDE也显示出与个别喷发一致的X射线耀斑。TDE和QPE也优先出现在类似的星系中。然而，没有确认的重复QPE与光谱确认的TDE或在峰值亮度下观察到的光学TDE有关。

在这里，研究者报告了从AT2019qiz探测到的9个平均复发时间约为48小时的X射线QPE， AT2019qiz是一个附近和广泛研究的光学选择TDE。他们检测并模拟了吸积盘的X射线，紫外线（UV）和光学发射，并表明轨道天体与吸积盘碰撞为QPE提供了合理的解释。

▲ Abstract：

Quasi-periodic eruptions (QPEs) are luminous bursts of soft X-rays from the nuclei of galaxies, repeating on timescales of hours to weeks. The mechanism behind these rare systems is uncertain, but most theories involve accretion disks around supermassive black holes (SMBHs) undergoing instabilities or interacting with a stellar object in a close orbit. It has been suggested that this disk could be created when the SMBH disrupts a passing star, implying that many QPEs should be preceded by observable tidal disruption events (TDEs). Two known QPE sources show long-term decays in quiescent luminosity consistent with TDEs and two observed TDEs have exhibited X-ray flares consistent with individual eruptions. TDEs and QPEs also occur preferentially in similar galaxies15. However, no confirmed repeating QPEs have been associated with a spectroscopically confirmed TDE or an optical TDE observed at peak brightness. Here we report the detection of nine X-ray QPEs with a mean recurrence time of approximately 48 h from AT2019qiz, a nearby and extensively studied optically selected TDE. We detect and model the X-ray, ultraviolet (UV) and optical emission from the accretion disk and show that an orbiting body colliding with this disk provides a plausible explanation for the QPEs.

Electronic rotons and Wigner crystallites in a two-dimensional dipole liquid

二维偶极子液体中的电子质子和维格纳晶体

▲ 作者：Soobin Park, Minjae Huh, Chris Jozwiak, Eli Rotenberg, Aaron Bostwick & Keun Su Kim

▲ 链接：

https://www.nature.com/articles/s41586-024-08045-0

▲ 摘要：

朗道提出的解释超流体液氦的一个关键概念是质子的量子粒子的基本激发。液体中原子的不规则排列导致了质子的非周期色散，这对理解分数量子霍尔液体（磁质子）和玻色-爱因斯坦凝聚体的超固体性起着关键作用。即使对于二维电子或偶极子液体，在没有磁场的情况下，排斥性相互作用也被预测会形成一个旋转最小值，这可以用来追踪向维格纳晶体和超导的转变，尽管这还没有被观察到。

在这里，研究者报告了在碱金属离子的二维偶极子液体中观察到的这种电子质子向黑磷的表层提供电子。他们的数据揭示了惊人的非周期色散，其特征是有限动量下的局部能量最小。随着偶极子密度的降低，相互作用超过了动能，质子间隙减小到0，就像在晶体中一样，这是维格纳结晶的信号。该模型显示了由偶极子之间的斥力引起的短程有序的重要性，这可以看作是漂浮在费米液体海洋中的维格纳晶体（气泡或条纹）的形成。研究结果表明，电子质子（和赝隙）的主要起源是强相关的。

▲ Abstract：

A key concept proposed by Landau to explain superfluid liquid helium is the elementary excitation of quantum particles called rotons. The irregular arrangement of atoms in a liquid leads to the aperiodic dispersion of rotons, which played a pivotal role in understanding fractional quantum Hall liquids (magneto-rotons) and the supersolidity of Bose–Einstein condensates. Even for a two-dimensional electron or dipole liquid, in the absence of a magnetic field, the repulsive interactions have been predicted to form a roton minimum, which can be used to trace the transition to Wigner crystals and superconductivity although this has not yet been observed. Here, we report the observation of such electronic rotons in a two-dimensional dipole liquid of alkali-metal ions donating electrons to surface layers of black phosphorus. Our data reveal the striking aperiodic dispersion of rotons, which is characterized by a local minimum of energy at finite momentum. As the density of dipoles decreases so that interactions dominate over the kinetic energy, the roton gap reduces to 0, as in a crystal, signalling Wigner crystallization. Our model shows the importance of short-range order arising from repulsion between dipoles, which can be viewed as the formation of Wigner crystallites (bubbles or stripes) floating in the sea of a Fermi liquid. Our results reveal that the primary origin of electronic rotons (and the pseudogap) is strong correlations.

生态学Ecology

Islands are key for protecting the world’s plant endemism

岛屿对保护世界特有植物很关键

▲ 作者：Julian Schrader, Patrick Weigelt, Lirong Cai, Mark Westoby, José María Fernández-Palacios, Francisco J. Cabezas, Gregory M. Plunkett, Tom A. Ranker, Kostas A. Triantis, Panayiotis Trigas, Yasuhiro Kubota & Holger Kreft

▲ 链接：

https://www.nature.com/articles/s41586-024-08036-1

▲ 摘要：

岛屿是著名的天然进化实验室，支持着许多在其他地方找不到的物种。岛屿的保护也值得高度关注，许多岛屿特有物种目前受到威胁或已灭绝。在这里，研究者提出了一份标准化的清单，列出了所有已知的维管植物，并记录了它们的地理和系统发育分布以及保护风险。

研究者对304103种植物的分析表明，94052种（31%）原生于岛屿，占全球陆地面积的5.3%。其中，63280种是岛屿特有物种，占全球植物多样性的21%。其中四分之三仅限于大型或孤立的岛屿。与世界植物区系相比，岛屿特有植物在生命树中是非随机分布的，共有1.005亿年独特的系统发育历史，其中17个科、1702个属完全是岛屿特有的。

在国际自然保护联盟指定的所有维管植物保护类别中，22%是岛屿特有植物。在这些特有物种中，51%受到威胁，55%有记录的全球灭绝发生在岛屿上。研究者发现，在所有单岛特有物种中，只有6%出现在符合联合国30×30保护目标的岛屿上。需要采取紧急措施，包括恢复生境、清除入侵物种和移地方案，以保护世界岛屿植物群。研究者表示，该清单量化了岛屿生物的独特性，为未来的岛屿植物区系研究提供了基础，并强调了采取保护行动的迫切需要。

▲ Abstract：

Islands are renowned as evolutionary laboratories and support many species that are not found elsewhere. Islands are also of great conservation concern, with many of their endemic species currently threatened or extinct. Here we present a standardized checklist of all known vascular plants that occur on islands and document their geographical and phylogenetic distribution and conservation risk. Our analyses of 304,103 plant species reveal that 94,052 species (31%) are native to islands, which constitute 5.3% of the global landmass4. Of these, 63,280 are island endemic species, which represent 21% of global plant diversity. Three-quarters of these are restricted to large or isolated islands. Compared with the world flora, island endemics are non-randomly distributed within the tree of life, with a total of 1,005 billion years of unique phylogenetic history with 17 families and 1,702 genera being entirely endemic to islands. Of all vascular plants assigned International Union for Conservation of Nature conservation categories, 22% are island endemics. Among these endemic species, 51% are threatened, and 55% of all documented global extinctions have occurred on islands. We find that of all single-island endemic species, only 6% occur on islands meeting the United Nations 30×30 conservation target. Urgent measures including habitat restoration, invasive species removal and ex situ programmes are needed to protect the world’s island flora. Our checklist quantifies the uniqueness of island life, provides a basis for future studies of island floras, and highlights the urgent need to take actions for conserving them.

Continental-scale nutrient and contaminant delivery by Pacific salmon

太平洋鲑鱼可在大陆层面输送养分和污染物

▲ 作者：Jessica E. Brandt, Jeff S. Wesner, Gregory T. Ruggerone, Timothy D. Jardine, Collin A. Eagles-Smith, Gabrielle E. Ruso, Craig A. Stricker, Kristofor A. Voss & David M. Walters

▲ 链接：

https://www.nature.com/articles/s41586-024-07980-2

▲ 摘要：

迁徙动物携带的大量营养物质对食物网具有生态效益，但可能被共同运输的污染物所抵消。鲑鱼产卵洄游是这一过程的典型，将海洋来源的物质带到内陆生态系统。在那里它们刺激了当地的生产力，但也增加了污染物的暴露。现在太平洋鲑鱼的丰度和生物量都比上个世纪高，这反映了群落结构的重大变化，这种变化可能改变了营养物和污染物的输送。

研究者将营养物质和污染物浓度与40年的太平洋鲑鱼年回报结合起来，量化群落结构的变化如何影响北美西部的海洋到淡水输入。鲑鱼每年向淡水输送数吨的营养物质和数公斤的污染物。鲑鱼收益的增加（1976-2015年）使鲑鱼来源的营养物和污染物投入分别增加了30%和20%。这些增加的主要是粉红鲑鱼，它们寿命短，在海洋食物网中的摄取量比其他鲑鱼低，而且营养与污染物的比例最高。

因此，研究者表示，营养物质的输送比污染物的输送速度更快，随着时间的推移，鲑鱼的投入对生态更有益。即便如此，污染物的负荷可能代表了一些鲑鱼捕食者的暴露问题。太平洋鲑鱼的例子展示了长期的环境变化如何与大空间尺度上的营养物质和污染物运动相互作用，并为探索其他迁徙物种的类似模式提供了一个模型。

▲ Abstract：

The movement of large amounts of nutrients by migrating animals has ecological benefits for recipient food webs that may be offset by co-transported contaminants. Salmon spawning migrations are archetypal of this process, carrying marine-derived materials to inland ecosystems where they stimulate local productivity but also enhance contaminant exposure. Pacific salmon abundance and biomass are higher now than in the last century, reflecting substantial shifts in community structure8 that probably altered nutrient versus contaminant delivery. Here we combined nutrient and contaminant concentrations with 40 years of annual Pacific salmon returns to quantify how changes in community structure influenced marine to freshwater inputs to western North America. Salmon transported tonnes of nutrients and kilograms of contaminants to freshwaters annually. Higher salmon returns (1976–2015) increased salmon-derived nutrient and contaminant inputs by 30% and 20%, respectively. These increases were dominated by pink salmon, which are short-lived, feed lower in marine food webs than other salmon species, and had the highest nutrient-to-contaminant ratios. As a result, the delivery of nutrients increased at a greater rate than the delivery of contaminants, and salmon inputs became more ecologically beneficial over time. Even still, contaminant loadings may represent exposure concerns for some salmon predators. The Pacific salmon example demonstrates how long-term environmental changes interact with nutrient and contaminant movement across large spatial scales and provides a model for exploring similar patterns with other migratory species.