編譯 | 李言
Nature, 1 February 2024, Volume 626 Issue 7997
《自然》, 2024年2月1日，第626卷，7997期
物理學Physics
Observation of interband Berry phase in laser-driven crystals
激光驅動晶體中的帶間貝里相位的觀察
▲ 作者：Ayelet J. Uzan-Narovlansky, Lior Faeyrman et al.
▲ 鏈接：
https://www.nature.com/articles/s41586-023-06828-5
▲ 摘要：
在此，我們演示了驅動晶體中貝里相位的一種新表現，其中電子波函數在不同波段之間的離散演化過程中積累幾何相位，同時保持過程的相干性。
我們通過實驗揭示了這一相位，通過使用強激光場來設計內部干涉儀，在不到一個驅動場的周期內誘導，將相位映射到高次諧波的發射上。
我們的工作為幾何相位的研究提供了機會，可以便于在光驅動拓撲現象和阿秒固體物理中進行各種觀測。
▲ Abstract：
Here we introduce and demonstrate a conceptually new manifestation of the Berry phase in light-driven crystals, in which the electronic wavefunction accumulates a geometric phase during a discrete evolution between different bands, while preserving the coherence of the process. We experimentally reveal this phase by using a strong laser field to engineer an internal interferometer, induced during less than one cycle of the driving field, which maps the phase onto the emission of higher-order harmonics. Our work provides an opportunity for the study of geometric phases, leading to a variety of observations in light-driven topological phenomena and attosecond solid-state physics.
材料科學Materials Science
High-quality semiconductor fibres via mechanical design
通過機械設計制備高質量半導體纖維
▲ 作者：Zhixun Wang, Zhe Wang et al.
▲ 鏈接：
https://www.nature.com/articles/s41586-023-06946-0
▲ 摘要：
在此，我們通過研究纖維形成的三個階段（粘性流動、芯結晶和隨后的冷卻）的應力發展和毛細不穩定性，報告了一種可以實現超長、無斷裂和無擾動無機半導體纖維的機械設計。
然后，可以將暴露的半導體線集成到單一的柔性光纖中，并與金屬電極具有良好的接口，從而實現光電光纖和大規模光電織物。這項研究提供了極端力學和流體動力學的見解，這些幾何形狀在傳統平臺中是無法實現的，從而解決了對柔性和可穿戴光電子器件日益增長的需求。
▲ Abstract：
Here we report a mechanical design to achieve ultralong, fracture-free and perturbation-free semiconductor fibres, guided by a study on stress development and capillary instability at three stages of the fibre formation: the viscous flow, the core crystallization and the subsequent cooling stage. Then, the exposed semiconductor wires can be integrated into a single flexible fibre with well-defined interfaces with metal electrodes, thereby achieving optoelectronic fibres and large-scale optoelectronic fabrics. This work provides fundamental insights into extreme mechanics and fluid dynamics with geometries that are inaccessible in traditional platforms, essentially addressing the increasing demand for flexible and wearable optoelectronics.
化學Chemistry
Structural transition and migration of incoherent twin boundary in diamond
金剛石中非共格孿晶界的結構轉變與遷移
▲ 作者：Ke Tong, Xiang Zhang, Zihe Li et al.
▲ 鏈接：
https://www.nature.com/articles/s41586-023-06908-6
▲ 摘要：
在此，我們報告了在室溫下金剛石中六種非共格孿晶界（ITB）特征和結構轉變的原子觀察，顯示了不同于金屬系統的位錯介導機制。主導ITBs不對稱且流動性較差，對納米孿晶金剛石的持續硬化起重要作用。
我們的研究結果揭示了金剛石和共價材料中的晶界行為，指出了開發高性能納米孿晶材料的新策略。
▲ Abstract：
Here we report atomic observations of six ITB configurations and structural transitions in diamond at room temperature, showing a dislocation-mediated mechanism different from metallic systems. The dominant ITBs are asymmetric and less mobile, contributing strongly to continuous hardening in nanotwinned diamond. The potential driving forces of ITB activities are discussed. Our findings shed new light on GB behaviour in diamond and covalent materials, pointing to a new strategy for development of high-performance, nanotwinned materials.
Durable CO2 conversion in the proton-exchange membrane system
質子交換膜系統中持久的二氧化碳轉化
▲ 作者：Wensheng Fang, Wei Guo, Ruihu Lu et al.
▲ 鏈接：
https://www.nature.com/articles/s41586-023-06917-5
▲ 摘要：
在此，我們開發了一種質子交換膜系統，該系統在源自廢鉛酸電池的催化劑下將二氧化碳還原為甲酸，其中晶格碳活化機制起作用。當二氧化碳還原與氫氧化耦合時，甲酸法拉第效率超過93%。
該系統與啟動/關閉過程兼容，在電流密度為600 mA cm-2和電池電壓為2.2 V的情況下，二氧化碳的單通轉換效率接近91%，連續工作時間超過5200小時。我們期望通過使用強大而高效的催化劑、穩定的三相界面和耐用的膜，這種卓越的性能將有助于推動碳中和技術的發展。
▲ Abstract：
Herein we develop a proton-exchange membrane system that reduces CO2 to formic acid at a catalyst that is derived from waste lead–acid batteries and in which a lattice carbon activation mechanism contributes. When coupling CO2 reduction with hydrogen oxidation, formic acid is produced with over 93% Faradaic efficiency. The system is compatible with start-up/shut-down processes, achieves nearly 91% single-pass conversion efficiency for CO2 at a current density of 600 mA cm-2 and cell voltage of 2.2 V and is shown to operate continuously for more than 5,200 h. We expect that this exceptional performance, enabled by the use of a robust and efficient catalyst, stable three-phase interface and durable membrane, will help advance the development of carbon-neutral technologies.
Stereodivergent 1,3-difunctionalization of alkenes by charge relocation
通過電荷重定位研究烯烴立體發散1,3-雙官能化
▲ 作者：Bogdan R. Brutiu, Giulia Iannelli et al.
▲ 鏈接：
https://www.nature.com/articles/s41586-023-06938-0
▲ 摘要：
在此，我們介紹一種基于名為“電荷重定位”概念的1,3-烯烴直接雙官能團化方法，該方法可以使未活化的烯烴以立體發散的方式獲得正構或反構的1,3-雙官能團化產物，而不需要定向基團或穩定特征。該方法的有效性在肺毒素4-ipomeanol及其衍生物的合成中得到了證明。
▲ Abstract：
Here we introduce a method for the direct 1,3-difunctionalization of alkenes, based on a concept termed ‘charge relocation’, which enables stereodivergent access to 1,3-difunctionalized products of either syn- or anti-configuration from unactivated alkenes, without the need for directing groups or stabilizing features. The usefulness of the approach is demonstrated in the synthesis of the pulmonary toxin 4-ipomeanol and its derivatives.
生態學Ecology
Top-predator recovery abates geomorphic decline of a coastal ecosystem
頂級捕食者復蘇減緩了沿海生態系統的地貌退化
▲ 作者：Brent B. Hughes, Kathryn M. Beheshti et al.
▲ 鏈接：
https://www.nature.com/articles/s41586-023-06959-9
▲ 摘要：
在此，我們將觀測和實驗數據結合起來，揭示了海獺在美國河口的重新定居產生了一個營養級聯，促進了沿海濕地植物的生物量，抑制了沼澤邊緣的侵蝕，否則這一過程會導致棲息地和生態系統服務的嚴重喪失。
幾十年來對Elkhorn Slough河口的監測表明，該系統中存在自上而下的控制，因為盡管系統中的物理壓力（即營養負荷、海平面上升和潮汐沖刷）持續增加，但隨著海獺數量的增加，鹽沼邊緣的侵蝕總體上有所減緩。在5條沼澤小溪中進行的捕食者排除實驗表明，海獺抑制了穴居蟹的數量，這是一種自上而下的效應，它增加了沼澤邊緣的強度，減少了沼澤的侵蝕。
多條溪流的調查比較了海獺定居前后的沼澤溪，證實了關鍵海獺、穴居蟹和沼澤溪之間存在相互作用，證明了捕食者控制生態系統邊緣過程的空間普遍性：在海獺重新定居水平較高的小溪中，穴居蟹的密度和邊緣侵蝕明顯下降。這些結果表明，營養退化可能是導致沿海濕地喪失的一個重要、但未被充分認識的因素，這表明頂級捕食者的復蘇有助于重建地貌穩定性。
▲ Abstract：
Here we combine observational and experimental data to reveal that recolonization of sea otters in a US estuary generates a trophic cascade that facilitates coastal wetland plant biomass and suppresses the erosion of marsh edges—a process that otherwise leads to the severe loss of habitats and ecosystem services. Monitoring of the Elkhorn Slough estuary over several decades suggested top-down control in the system, because the erosion of salt marsh edges has generally slowed with increasing sea otter abundance, despite the consistently increasing physical stress in the system (that is, nutrient loading, sea-level rise and tidal scour). Predator-exclusion experiments in five marsh creeks revealed that sea otters suppress the abundance of burrowing crabs, a top-down effect that cascades to both increase marsh edge strength and reduce marsh erosion. Multi-creek surveys comparing marsh creeks pre- and post-sea otter colonization confirmed the presence of an interaction between the keystone sea otter, burrowing crabs and marsh creeks, demonstrating the spatial generality of predator control of ecosystem edge processes: densities of burrowing crabs and edge erosion have declined markedly in creeks that have high levels of sea otter recolonization. These results show that trophic downgrading could be a strong but underappreciated contributor to the loss of coastal wetlands, and suggest that restoring top predators can help to re-establish geomorphic stability.
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