编译 | 冯维维
Nature, 16 November 2023, Volume 623 Issue 7987
《自然》, 2023年11月16日，第623卷，7987期
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物理学Physics
A Milky Way-like barred spiral galaxy at a redshift of 3
红移为3的类似银河系的棒旋星系
▲ 作者：Luca Costantin, Pablo G. Pérez-González, Yuchen Guo, Chiara Buttitta, Shardha Jogee, Micaela B. Bagley, Guillermo Barro, Mauro Giavalisco, L. Y. Aaron Yung, etc.
▲ 链接：
https://www.nature.com/articles/s41586-023-06636-x
▲ 摘要：
本地宇宙中的大多数大质量盘状星系在其中心区域显示出恒星棒状结构，包括银河系。棒状应该是在低红移的动态冷恒星盘中形成的，因为在高红移的盘状星系中典型的强烈气体湍流抑制或延迟了棒子的形成。
此外，模拟预测，在类银河系星系的祖先星系中，超过z = 1.5的条形几乎不存在。研究者报告了对ceers-2112的观测，这是一个红移z≈3的棒旋星系，在宇宙只有20亿年的时候就已经成熟了。
恒星质量和棒状形态意味着，就宇宙前20亿年的结构和质量历史而言，ceers-2112可以被认为是银河系的祖先，而在宇宙40亿年时两者质量最接近。研究者推断，该星系中的重子可能已经在z≈3时主导了暗物质，高红移条可能在大约4亿年时形成，动态冷星盘可能在红移z = 4~5时形成。
▲ Abstract：
The majority of massive disk galaxies in the local Universe show a stellar barred structure in their central regions, including our Milky Wa. Bars are supposed to develop in dynamically cold stellar disks at low redshift, as the strong gas turbulence typical of disk galaxies at high redshift suppresses or delays bar formation. Moreover, simulations predict bars to be almost absent beyond z = 1.5 in the progenitors of Milky Way-like galaxies. Here we report observations of ceers-2112, a barred spiral galaxy at redshift zphot ≈ 3, which was already mature when the Universe was only 2 Gyr old. The stellar mass and barred morphology mean that ceers-2112 can be considered a progenitor of the Milky Way, in terms of both structure and mass-assembly history in the first 2 Gyr of the Universe, and was the closest in mass in the first 4 Gyr. We infer that baryons in galaxies could have already dominated over dark matter at z ≈ 3, that high-redshift bars could form in approximately 400 Myr and that dynamically cold stellar disks could have been in place by redshift z = 4–5 (more than 12 Gyrs ago).
Quantum gas mixtures and dual-species atom interferometry in space
空间中的量子气体混合物和双种原子干涉测量
▲ 作者：Ethan R. Elliott, David C. Aveline, Nicholas P. Bigelow, Patrick Boegel, Sofia Botsi, Eric Charron, José P. D’Incao, Jason R. Williams, etc.
▲ 链接：
https://www.nature.com/articles/s41586-023-06645-w
▲ 摘要：
在小型仪器中达到超冷原子温度的能力最近已扩展到太空。超冷的温度放大了量子效应，而自由落体则允许进一步冷却，并延长与引力的相互作用时间——引力是没有量子描述的最终力量。
在地球上，这些装置产生了宏观的量子现象，如玻色—爱因斯坦凝聚（BECs）、超流体和强相互作用的量子气体。干扰两个超冷原子同位素叠加的地面量子传感器在10?12能级测试了自由落体（UFF）的普遍性，这是爱因斯坦经典引力理论的核心原则。在太空中，为探索强相互作用的丰富物理学或对UFF进行量子测试所需的冷却元素仍然是难以捉摸的。
研究者利用国际空间站（ISS）上的多用户冷原子实验室（CAL）仪器的升级硬件，首次在太空中同时产生了双种BEC（由87Rb和41K形成），观察了其中的相互作用，产生了39K超冷气体。在“神奇波长”下操作单个激光器，同时应用布拉格脉冲的拉比速率相等，研究者进一步实现了两种原子（87Rb和41K）同时原子干涉测量的首次星载演示。
这些结果是在空间中进行UFF量子测试的重要一步，将使科学家能够在没有引力不对称干扰的新场景下研究少体物理学、量子化学和基础物理学的各个方面。
▲ Abstract：
The capability to reach ultracold atomic temperatures in compact instruments has recently been extended into space. Ultracold temperatures amplify quantum effects, whereas free fall allows further cooling and longer interactions time with gravity—the final force without a quantum description. On Earth, these devices have produced macroscopic quantum phenomena such as Bose–Einstein condensates (BECs), superfluidity, and strongly interacting quantum gases3. Terrestrial quantum sensors interfering the superposition of two ultracold atomic isotopes have tested the universality of free fall (UFF), a core tenet of Einstein’s classical gravitational theory, at the 10?12 level4. In space, cooling the elements needed to explore the rich physics of strong interactions or perform quantum tests of the UFF has remained elusive. Here, using upgraded hardware of the multiuser Cold Atom Lab (CAL) instrument aboard the International Space Station (ISS), we report, to our knowledge, the first simultaneous production of a dual-species BEC in space (formed from 87Rb and 41K), observation of interspecies interactions, as well as the production of 39K ultracold gases. Operating a single laser at a ‘magic wavelength’ at which Rabi rates of simultaneously applied Bragg pulses are equal, we have further achieved the first spaceborne demonstration of simultaneous atom interferometry with two atomic species (87Rb and 41K). These results are an important step towards quantum tests of UFF in space and will allow scientists to investigate aspects of few-body physics, quantum chemistry and fundamental physics in new regimes without the perturbing asymmetry of gravity.
Kinetic magnetism in triangular moiré materials
三角莫尔材料的动力学磁性
▲ 作者：L. Ciorciaro, T. Smoleński, I. Morera, N. Kiper, S. Hiestand, M. Kroner, Y. Zhang, K. Watanabe, T. Taniguchi, E. Demler & A. imamo?lu
▲ 链接：
https://www.nature.com/articles/s41586-023-06633-0
▲ 摘要：
从传统的铁磁性金属到强相关材料（如铜酸盐），材料的磁性源于库仑交换相互作用。理论上已经讨论了可以自然地促进电气控制的磁的替代机制的存在，但在扩展系统中的实验证明一直缺失。
研究者分析了MoSe2/WS2在Mott绝缘体态附近形成受挫三角晶格的范德华异质结构，并观察到源于动力学机制的磁相关的直接证据。
通过极化选择性吸引极子共振的强度直接测量电子磁化强度，他们发现当Mott态被电子掺杂时，系统表现出与Nagaoka机制一致的铁磁相关性。
▲ Abstract：
Magnetic properties of materials ranging from conventional ferromagnetic metals to strongly correlated materials such as cuprates originate from Coulomb exchange interactions. The existence of alternate mechanisms for magnetism that could naturally facilitate electrical control has been discussed theoretically, but an experimental demonstration8 in an extended system has been missing. Here we investigate MoSe2/WS2 van der Waals heterostructures in the vicinity of Mott insulator states of electrons forming a frustrated triangular lattice and observe direct evidence of magnetic correlations originating from a kinetic mechanism. By directly measuring electronic magnetization through the strength of the polarization-selective attractive polaron resonance, we find that when the Mott state is electron-doped, the system exhibits ferromagnetic correlations in agreement with the Nagaoka mechanism.
Dynamic diagnosis of metamaterials through laser-induced vibrational signatures
利用激光诱导振动特征对超材料进行动态诊断
▲ 作者：Yun Kai, Somayajulu Dhulipala, Rachel Sun, Jet Lem, Washington DeLima, Thomas Pezeril & Carlos M. Portela
▲ 链接：
https://www.nature.com/articles/s41586-023-06652-x
▲ 摘要：
微观尺度的机械超材料由于其工程构建块而表现出奇异的静态特性，但其动态特性仍然很少被探索。这些材料的设计原则可以针对频率相关的特性和高应变率变形下的弹性，使其成为轻质抗冲击、声波波导或振动阻尼的通用材料。
然而，由于低通量和破坏性表征或缺乏现有的测试协议，在小尺度上获取动态特性仍然是一个挑战。研究者展示了一种高通量、非接触的框架，该框架使用超材料中的兆赫波传播特征来非破坏性地提取动态线性特性、全方位弹性信息、阻尼特性和缺陷量化。
使用微观超材料的棒状镶嵌，研究者报告了高达94%的方向相关和速率相关的动态刚度，应变率接近102 s?1，以及比其组成材料高三倍的阻尼性能。
研究还表明，振动响应中的频移允许表征超材料中不可见的缺陷，选择性探测允许构建实验弹性表面，这在以前只能通过计算实现。该研究为加速数据驱动的材料和微设备的发现提供了一条途径，用于动态应用，如保护结构，医学超声或隔振。
▲ Abstract：
Mechanical metamaterials at the microscale exhibit exotic static properties owing to their engineered building blocks, but their dynamic properties have remained substantially less explored. Their design principles can target frequency-dependent properties and resilience under high-strain-rate deformation8 making them versatile materials for applications in lightweight impact resistance, acoustic waveguiding or vibration damping. However, accessing dynamic properties at small scales has remained a challenge owing to low-throughput and destructive characterization or lack of existing testing protocols. Here we demonstrate a high-throughput, non-contact framework that uses MHz-wave-propagation signatures within a metamaterial to non-destructively extract dynamic linear properties, omnidirectional elastic information, damping properties and defect quantification. Using rod-like tessellations of microscopic metamaterials, we report up to 94% direction-dependent and rate-dependent dynamic stiffening at strain rates approaching 102 s?1, as well as damping properties three times higher than their constituent materials. We also show that frequency shifts in the vibrational response allow for characterization of invisible defects within the metamaterials and that selective probing allows for the construction of experimental elastic surfaces, which were previously only possible computationally. Our work provides a route for accelerated data-driven discovery of materials and microdevices for dynamic applications such as protective structures, medical ultrasound or vibration isolation.
化学Chemistry
Anion–π interactions suppress phase impurities in FAPbI3 solar cells
阴离子-π相互作用抑制FAPbI3太阳能电池中的相杂质
▲ 作者：Zijian Huang, Yang Bai, Xudan Huang, Jiatong Li, Yuetong Wu, Yihua Chen, Kailin Li, Xiuxiu Niu, Nengxu Li, Guilin Liu, Yu Zhang, Huachao Zai, Qi Chen, Ting Lei, Lifen Wang & Huanping Zhou
▲ 链接：
https://www.nature.com/articles/s41586-023-06637-w
▲ 摘要：
实现高效和长期稳定是钙钛矿太阳能电池（PSCs）商业化的关键。然而，钙钛矿（ABX3）成分和相的多样性使得制备高质量的薄膜具有挑战性。钙钛矿的形成依赖于AX和BX2之间的反应，而大多数常规的膜生长调节方法仅基于与BX2组分的相互作用。
研究者展示了一种通过阴离子—π相互作用调节AX和六氟苯（HFB）反应动力学的替代方法。值得注意的是，这两种方法是独立的，但共同建立了“双位点调控”，这实现了对AX和BX2之间反应的微妙控制，而不需要中间产物。制备的甲醛酰胺卤化铅（FAPbI3）薄膜缺陷少，吸收红移，相纯度高，无纳米级δ相。
因此，研究实现了PSCs的功率转换效率（PCE）在0.08 cm2器件中高达26.07%（认证为25.8%），在1 cm2器件中高达24.63%。在50±5°C的全光谱AM 1.5 G阳光下，在最大功率点（MPP）跟踪1258小时后，该器件还保持了94%的初始PCE。该方法通过探索阴离子—π相互作用，扩大了钙钛矿前驱体中发生的化学相互作用的范围，并突出了AX组分作为一种新的有效工作场所的重要性，以改进具有高质量和相纯度的光伏器件。
▲ Abstract：
Achieving both high efficiency and long-term stability is the key to the commercialization of perovskite solar cells (PSCs). However, the diversity of perovskite (ABX3) compositions and phases makes it challenging to fabricate high-quality films. Perovskite formation relies on the reaction between AX and BX2, whereas most conventional methods for film-growth regulation are based solely on the interaction with the BX2 component. Herein, we demonstrate an alternative approach to modulate reaction kinetics by anion–π interaction between AX and hexafluorobenzene (HFB). Notably, these two approaches are independent but work together to establish ‘dual-site regulation’, which achieves a delicate control over the reaction between AX and BX2 without unwanted intermediates. The resultant formamidinium lead halides (FAPbI3) films exhibit fewer defects, redshifted absorption and high phase purity without detectable nanoscale δ phase. Consequently, we achieved PSCs with power conversion efficiency (PCE) up to 26.07% for a 0.08-cm2 device (25.8% certified) and 24.63% for a 1-cm2 device. The device also kept 94% of its initial PCE after maximum power point (MPP) tracking for 1,258 h under full-spectrum AM1.5G sunlight at 50 ± 5°C. This method expands the range of chemical interactions that occur in perovskite precursors by exploring anion–π interactions and highlights the importance of the AX component as a new and effective working site to improved photovoltaic devices with high quality and phase purity.
Arenium-ion-catalysed halodealkylation of fully alkylated silanes
全烷基化硅烷的卤代脱烷基反应
▲ 作者：Tao He, Hendrik F. T. Klare & Martin Oestreich
▲ 链接：
https://www.nature.com/articles/s41586-023-06646-9
▲ 摘要：
“有机硅”不存在于自然界，但现代化学很难想象没有硅与碳结合的情况。虽然含有硅的商品化学品，如那些从“直接工艺”中出现的化学品看起来很简单，但选择性地制备芳基取代和烷基取代（功能化）硅化合物（称为硅烷）并非易事。氯硅烷如Me4?nSiCln (n=1-3)和SiCl4(n=4)是合成含硅分子的常见起点。
然而，这些方法往往存在分离问题。相反，具有四个烷基的硅烷被认为是合成的死角。研究者介绍了一种芳烃离子催化的卤化脱烷基反应，有效地将Me3Si和相关的季硅烷转化为各种功能化衍生物。
该反应使用烷基卤化物和芳烃溶剂：烷基卤化物是卤化物源，最终与芳烃进行傅克酰基化反应以再生催化剂，而芳烃离子在原脱烷基过程中充当强勃朗斯特酸。例如，在硅药物前体的合成中，证明了自上而下的卤代脱烷基方法优于报道的自下而上的程序。
此外，与烷基链相连的惰性Me3Si基团的化学选择性氯去甲基化随后的氧化降解被证明是玉尾—弗莱明氧化型醇形成的一个入口。
▲ Abstract：
‘Organic silicon’ is not found in nature but modern chemistry is hard to imagine without silicon bound to carbon. Although silicon-containing commodity chemicals such as those emerging from the ‘direct process’look simple, it is not trivial to selectively prepare aryl-substituted and alkyl-substituted (functionalized) silicon compounds, known as silanes. Chlorosilanes such as Me4?nSiCln (n= 1–3) as well as SiCl4 (n=4) are common starting points for the synthesis of silicon-containing molecules. Yet these methods often suffer from challenging separation problems. Conversely, silanes with four alkyl groups are considered synthetic dead ends. Here we introduce an arenium-ion-catalysed halodealkylation that effectively converts Me4Si and related quaternary silanes into a diverse range of functionalized derivatives. The reaction uses an alkyl halide and an arene (co)solvent: the alkyl halide is the halide source that eventually engages in a Friedel–Crafts alkylation with the arene to regenerate the catalyst, whereas the arenium ion acts as a strong Br nsted acid for the protodealkylation step. The advantage of the top-down halodealkylation methodology over reported bottom-up procedures is demonstrated, for example, in the synthesis of a silicon drug precursor. Moreover, chemoselective chlorodemethylation of the rather inert Me3Si group attached to an alkyl chain followed by oxidative degradation is shown to be an entry into Tamao–Fleming-type alcohol formation.
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