《自然》（20220428出版）一周论文导读

编译 | 李言

Nature, 28 April 2022, Volume 604 Issue 7907

《自然》2022年4月28日，第604卷，7907期

天文学Astronomy

Early Solar System instability triggered by dispersal of the gaseous disk

气体盘的耗散触发早期太阳系的不稳定性

作者：Beibei Liu, Sean N. Raymond & Seth A. Jacobson

链接：

https://www.nature.com/articles/s41586-022-04535-1

摘要：

在此，我们使用动态模拟表明，巨行星的不稳定性可能是由气体盘的耗散触发的。当气体盘从内到外蒸发时，它的内缘依次扫过并依次动态地扰乱了每颗行星的轨道。相关的轨道移动导致系统外部的动力压缩，最终引发不稳定性。

在天体物理参数的可行范围内，我们模拟系统的最终轨道与太阳系的轨道相匹配。因此，巨大行星的不稳定性发生在气体盘耗散的时候，根据天文观测，这是在太阳系诞生后的几百万年到一千万年间。

类地行星的形成直到如此早期的巨行星不稳定之后才完成；不断增长的类地行星甚至可能是被它的扰动塑造的，这解释了为什么火星相对于地球的质量较小。

Abstract：

Here we use dynamical simulations to show that the giant planets’ instability was probably triggered by the dispersal of the gaseous disk. As the disk evaporated from the inside out, its inner edge swept successively across and dynamically perturbed each planet’s orbit in turn. The associated orbital shift caused a dynamical compression of the exterior part of the system, ultimately triggering instability. The final orbits of our simulated systems match those of the Solar System for a viable range of astrophysical parameters. The giant planet instability therefore took place as the gaseous disk dissipated, constrained by astronomical observations to be a few to ten million years after the birth of the Solar System. Terrestrial planet formation would not complete until after such an early giant planet instability; the growing terrestrial planets may even have been sculpted by its perturbations, explaining the small mass of Mars relative to Earth.

物理学Physics

Observation of a linked-loop quantum state in a topological magnet

拓扑磁体中链环量子态的观察

作者：Ilya Belopolski, Guoqing Chang, Tyler A. Cochran, Zi-Jia Cheng et al.

链接：

https://www.nature.com/articles/s41586-022-04512-8

摘要：

在此，我们报告一个与在镜像对称铁磁体中电子带交叉环线相关的不寻常的连接数（扭结理论）不变量。利用最先进的光谱方法，我们直接观察到材料的三环体T3布里渊区中三个纠缠在一起的简并环。

我们发现每个环连接其他环两次。通过系统光谱研究这一链环量子态，我们明确地画出了它的链图，并类比结理论，得出它的链数为(2,2,2)，从实验数据直接确定了它的不变结构。

我们进一步预测和观察了样品表面的塞弗特边界态，该边界态由体链环保护，表明了显著的塞弗特体边界响应。我们对量子环链的观察，推动了扭结理论在探索磁性和超导量子物质方面的应用。

Abstract：

Here we report an unusual linking-number (knot theory) invariant associated with loops of electronic band crossings in a mirror-symmetric ferromagnet. Using state-of-the-art spectroscopic methods, we directly observe three intertwined degeneracy loops in the material’s three-torus, T3, bulk Brillouin zone. We find that each loop links each other loop twice. Through systematic spectroscopic investigation of this linked-loop quantum state, we explicitly draw its link diagram and conclude, in analogy with knot theory, that it exhibits the linking number (2, 2, 2), providing a direct determination of the invariant structure from the experimental data. We further predict and observe, on the surface of our samples, Seifert boundary states protected by the bulk linked loops, suggestive of a remarkable Seifert bulk–boundary correspondence. Our observation of a quantum loop link motivates the application of knot theory to the exploration of magnetic and superconducting quantum matter.

The field-free Josephson diode in a van der Waals heterostructure

范德华异质结构中的无磁场约瑟夫森二极管

作者：Heng Wu, Yaojia Wang, Yuanfeng Xu, Pranava K. Sivakumar, Chris Pasco, Ulderico Filippozzi, Stuart S. P. Parkin, Yu-Jia Zeng, Tyrel McQueen & Mazhar N. Ali

链接：

https://www.nature.com/articles/s41586-022-04504-8

摘要：

在此，我们通过制作NbSe2/Nb3Br8/NbSe2的反转对称破缺范德华异质结构，实现了约瑟夫森二极管。

我们证明，即使没有磁场，结也可以在正电流下超导，同时在负电流下具有电阻性。ΔIc 行为（正和负临界电流之间的差异）与磁场是对称的，约瑟夫逊耦合可以通过夫劳恩霍夫模式证明。

同时，我们以极低的开关电流密度、高整流比和高鲁棒性实现了方波激励的稳定半波整流。这种非互易行为强烈违背了已知的约瑟夫森关系，并为通过量子材料与约瑟夫森结的整合打开了发现新的机制和物理现象的大门，并为超导量子器件提供了新的途径。

Abstract：

Here we realized the Josephson diode by fabricating an inversion symmetry breaking van der Waals heterostructure of NbSe2/Nb3Br8/NbSe2. We demonstrate that even without a magnetic field, the junction can be superconducting with a positive current while being resistive with a negative current. The ΔIc behaviour (the difference between positive and negative critical currents) with magnetic field is symmetric and Josephson coupling is proved through the Fraunhofer pattern. Also, stable half-wave rectification of a square-wave excitation was achieved with a very low switching current density, high rectification ratio and high robustness. This non-reciprocal behaviour strongly violates the known Josephson relations and opens the door to discover new mechanisms and physical phenomena through integration of quantum materials with Josephson junctions, and provides new avenues for superconducting quantum devices.

化学Chemistry

Machine learning-aided engineering of hydrolases for PET depolymerization

PET降解酶的机器学习辅助工程

作者：Hongyuan Lu, Daniel J. Diaz, Natalie J. Czarnecki, Congzhi Zhu et al.

链接：

https://www.nature.com/articles/s41586-022-04599-z

摘要：

在此，我们使用一种基于结构的机器学习算法来设计稳定和活跃的PET水解酶。我们的突变组合（FAST-PETase：具有功能性、活性、稳定和耐受性的PETase）与野生型PETase相比含有5个突变，在30 - 50 C和一系列pH水平范围内，与野生型和工程替代品相比，显示了优越的pet水解活性。

我们证明，来自51种消费者使用过的PET几乎都可以在1周内被FAST-PETase完全降解。FAST-PETase可以在50ºC下解聚商业水瓶和整个热预处理水瓶的未处理的无定形部分。

最后，我们通过利用FAST-PETase和回收的单体重新合成PET，展示了一个闭环PET回收过程。总而言之，我们的结果展示了一条工业化规模的酶塑料回收的可行途径。

Abstract：

Here, we use a structure-based, machine learning algorithm to engineer a robust and active PET hydrolase. Our mutant and scaffold combination (FAST-PETase: functional, active, stable and tolerant PETase) contains five mutations compared to wild-type PETase (N233K/R224Q/S121E from prediction and D186H/R280A from scaffold) and shows superior PET-hydrolytic activity relative to both wild-type and engineered alternatives between 30 and 50  C and a range of pH levels. We demonstrate that untreated, postconsumer-PET from 51 different thermoformed products can all be almost completely degraded by FAST-PETase in 1 week. FAST-PETase can also depolymerize untreated, amorphous portions of a commercial water bottle and an entire thermally pretreated water bottle at 50 ºC. Finally, we demonstrate a closed-loop PET recycling process by using FAST-PETase and resynthesizing PET from the recovered monomers. Collectively, our results demonstrate a viable route for enzymatic plastic recycling at the industrial scale.

Computer-designed repurposing of chemical wastes into drugs

计算设计方案将化学废料变为药物

作者：Agnieszka Wołos, Dominik Koszelewski, Rafał Roszak, Sara Szymkuć et al.

链接：

https://www.nature.com/articles/s41586-022-04503-9

摘要：

化学工业持续产生大量的化学废物，因此，设计“循环化学”方案以有效地将废料转化为有价值的产品是必要的。在这里，我们展示具有广泛合成知识的计算机如何帮助解决这一挑战。

使用正向合成Allchemy平台，我们从大约200种商业规模的回收废弃化学品中产生巨大的合成网络，从这些网络中回收数以万计的途径，可以产生约300种重要的药物和农药，然后根据可持续化学的公认指标，用算法对这些合成物进行排名。

通过实验，我们验证了其中几种途径，包括在“按需制药”流动化学平台上的工业现实展示。广泛采用这一废物利用的算法，可以加快化学品的生产性再利用，以避免废物产生的存储或抛弃成本，甚至可能造成的环境危害。

Abstract：

As the chemical industry continues to produce considerable quantities of waste chemicals, it is essential to devise ‘circular chemistry’ schemes to productively back-convert at least a portion of these unwanted materials into useful products. Here we show how computers equipped with broad synthetic knowledge can help address this challenge. Using the forward-synthesis Allchemy platform, we generate giant synthetic networks emanating from approximately 200 waste chemicals recycled on commercial scales, retrieve from these networks tens of thousands of routes leading to approximately 300 important drugs and agrochemicals, and algorithmically rank these syntheses according to the accepted metrics of sustainable chemistry. Several of these routes we validate by experiment, including an industrially realistic demonstration on a ‘pharmacy on demand’ flow-chemistry platform. Wide adoption of computerized waste-to-valuable algorithms can accelerate productive reuse of chemicals that would otherwise incur storage or disposal costs, or even pose environmental hazards.

Catalytic synthesis of phenols with nitrous oxide

一氧化二氮催化合成酚类化合物

作者：Franck Le Vaillant, Ana Mateos Calbet, Silvia González-Pelayo, Edward J. Reijerse, Shengyang Ni, Julia Busch & Josep Cornella

链接：

https://www.nature.com/articles/s41586-022-04516-4

摘要：

在这里，我们报道了在温和的条件下（室温，1.5-2 bar N2O）将N2O插入到Ni-C键中，从而释放有价值的酚和良性N2。这一完全不同的有机金属C-O成键步骤不同于目前基于还原消除反映的方法，并使芳卤代烃转化为酚的替代催化方法成为可能。

该过程通过联吡啶基的配体使镍中心具有催化作用。该方法具有稳定性、温和性和高度选择性，能够适应碱基敏感功能，并允许从密集功能化的芳卤化物合成苯酚。

虽然该方法没有提供缓解一氧化二氮排放的解决方案，但它为丰富的一氧化二氮作为氧源的温和重新估值提供了蓝图。

Abstract：

Here we report an insertion of N2O into a Ni‒C bond under mild conditions (room temperature, 1.5–2 bar N2O), thus delivering valuable phenols and releasing benign N2. This fundamentally distinct organometallic C‒O bond-forming step differs from the current strategies based on reductive elimination and enables an alternative catalytic approach for the conversion of aryl halides to phenols. The process was rendered catalytic by means of a bipyridine-based ligands for the Ni centre. The method is robust, mild and highly selective, able to accommodate base-sensitive functionalities as well as permitting phenol synthesis from densely functionalized aryl halides. Although this protocol does not provide a solution to the mitigation of N2O emissions, it represents a reactivity blueprint for the mild revalorization of abundant N2O as an O source.