《科学》(20210319出版)一周论文导读

2021年03月22日02:45:02 科学 1067

编译|冯维维


Science, 19 March 2021 Vol 371, Issue 6535

《科学》2021年3月19日,第371卷6535期

《科学》(20210319出版)一周论文导读 - 天天要闻


物理学Physics


Generating arbitrary topological windings of a non-Hermitian band

开放的拓扑

▲ 作者:Kai Wang, Avik Dutt, Ki Youl Yang, Casey C. Wojcik, Jelena Vučković, Shanhui Fan

▲ 链接:

https://science.sciencemag.org/content/371/6535/1240

▲ 摘要

控制系统的拓扑结构提供了一条路线来开发抗缺陷的鲁棒的设备。虽然早期的拓扑带理论发展集中在厄米特(封闭)系统上,但最近的努力已转向非厄米特(开放)系统。

作者报告了非厄密能带的拓扑非平凡绕组的测量和控制。通过在已调制的环形谐振器中实现由光学频率模构成的频率合成维上的非厄米特晶格哈密顿量,他们直接可视化了非平凡拓扑带绕组,并证明了该绕组是可以控制的。

这种控制为开放物理系统中拓扑非平凡相的实验合成、表征和控制提供了一条途径。

▲ Abstract

Controlling the topology of a system provides a route to develop devices that are robust against defects. Whereas earlier developments of topological band theory focused on Hermitian (closed) systems, recent efforts have been toward non-Hermitian (open) systems. K. Wang et al. report on the measurement and control of topologically nontrivial windings of a non-Hermitian energy band. By implementing non-Hermitian lattice Hamiltonians along a frequency synthetic dimension formed by optical frequency modes in a modulated ring-resonator, they directly visualized the nontrivial topological band winding and showed that the winding can be controlled. Such control provides a route for the experimental synthesis, characterization, and control of topologically nontrivial phases in open physical systems.


Tuning electron correlation in magic-angle twisted bilayer graphene using Coulomb screening

调节扭曲双层石墨烯中电子相关性

▲ 作者:Xiaoxue Liu, Zhi Wang, K. Watanabe, T. Taniguchi, Oskar Vafek, J. I. A. Li

▲ 链接:

https://science.sciencemag.org/content/371/6535/1261

▲ 摘要

要在扭曲双分子层石墨烯(MATBG)中解释超导状态的性质被证明很棘手。为了研究电子-电子关联在这种状态下的作用,作者在MATBG样品附近放置了另一层石墨烯双分子层,这一层采用了传统的石墨烯薄片排列方式。

通过改变传统双层膜中的载流子密度,研究人员控制了MATBG中的相互作用强度。减弱相互作用会增强超导性,这与电子-声子耦合与库仑相互作用竞争以稳定超导相的情况一致。

▲ Abstract

Elucidating the nature of the superconducting state in magic-angle twisted bilayer graphene (MATBG) has proven tricky. To study the role of electron-electron correlations in this state, Liu et al. placed another graphene bilayer, this one having a conventional arrangement of the graphene sheets, in the immediate vicinity of a sample of MATBG. By varying the carrier density in the conventional bilayer, the researchers controlled the strength of interactions in MATBG. Weakening the interactions strengthened superconductivity, consistent with scenarios in which the electron-phonon coupling competes against Coulomb interactions to stabilize the superconducting phase.


化学Chemistry

Detection of two interstellar polycyclic aromatic hydrocarbons via spectral matched filtering

星际多环芳烃的识别

▲ 作者:Brett A. McGuire, Ryan A. Loomis, Anthony J. Remijan, Michael C. McCarthy. Etc.

▲ 链接:

https://science.sciencemag.org/content/371/6535/1265

▲ 摘要

中红外光谱分析表明,多环芳烃(PAHs)大量存在于许多天体中,但该技术无法确定具体存在的多环芳烃分子。如果分子足够丰富且偶极矩很大,射电天文学可以提供单独的鉴定,但多环芳烃预计会产生大量非常弱的线。

作者对位于金牛座星际分子云内的TMC-1进行了叠加和匹配过滤分析,在射电观测中寻找多环芳烃。他们鉴定了小的多环芳烃氰基萘的两个同分异构体,两个连接着CN基团的苯环。

▲ Abstract

Midinfrared spectroscopy has shown that polycyclic aromatic hydrocarbons (PAHs) are abundant in many astronomical objects, but this technique cannot determine which specific PAH molecules are present. Radio astronomy could provide individual identifications if the molecule is sufficiently abundant and has a large dipole moment, but PAHs are expected to produce large numbers of very weak lines. McGuire et al. performed a stacking and matched filter analysis to search for PAHs in radio observations of TMC-1, located within the interstellar Taurus Molecular Cloud. They identified emission from two isomers of the small PAH cyanonapthalene, two fused benzene rings with a CN group attached.

Tandem In2O3-Pt/Al2O3 catalyst for coupling of propane dehydrogenation to selective H2 combustion

克服丙烯氧化

▲ 作者:Huan Yan, Kun He, Izabela A. Samek, Dian Jing, Macy G. Nanda, Peter C. Stair, Justin M. Notestein

▲ 链接:

https://science.sciencemag.org/content/371/6535/1257

▲ 摘要

丙烷氧化脱氢制丙烯和水的催化剂的选择性随着转化率的增加而降低,因为丙烯本身比丙烷更容易被氧化。

作者通过在丙烷脱氢催化剂上生长一种选择性氢燃烧催化剂氧化铟(一种约2纳米的外壳),并将铂纳米颗粒支撑在氧化铝球上,从而创造了纳米级串联催化剂。这种涂层使铂纳米颗粒暴露,以便丙烷脱氢。

在氧化铟-铂界面处,表面氢原子被氧化。这种方法使丙烯的产量提高到30%。

▲ Abstract

Catalysts for the oxidative dehydrogenation of propane to propylene and water become less selective with increasing conversion because propylene itself is more readily oxidized than propane. Yan et al. created nanoscale tandem catalysts by growing an ∼2-nanometer shell of indium oxide, a selective hydrogen combustion catalyst, over a propane dehydrogenation catalyst, platinum nanoparticles supported on alumina spheres. This overcoat exposed the platinum nanoparticles for propane dehydrogenation. Surface hydrogen atoms were oxidized at the indium oxide–platinum interface. This approach boosted yields of propylene to up to 30%.


地球科学Earth sciences

Record-breaking aerosol levels explained by smoke injection into the stratosphere

平流层烟雾可解释破纪录气溶胶含量

▲ 作者:Eitan Hirsch, Ilan Koren

▲ 链接:

https://science.sciencemag.org/content/371/6535/1269

▲ 摘要

2020年,澳大利亚大规模的森林大火向平流层排放了大量烟雾。赫希和科伦发现,这种烟雾在南半球造成了破纪录的悬浮颗粒水平,其程度堪比一次中度火山爆发。

造成这种严重程度的原因是火灾的强度及其所处纬度的对流层顶较浅和中纬度气旋带。这种气溶胶的增加导致了海洋无云地区的大量降温。

▲ Abstract

Intense, widespread bushfires in Australia injected huge amounts of smoke into the stratosphere in 2020. Hirsch and Koren found that this smoke caused record-breaking levels of aerosols over the Southern Hemisphere, as much as that from a moderate volcanic eruption. The severity was caused by a combination of the vigor of the fires and their location at a latitude with a shallow tropopause and within the midlatitude cyclones belt. This aerosol increase caused considerable cooling over oceanic cloud-free areas.

Manta-like planktivorous sharks in Late Cretaceous oceans

恐龙时代的浮游食性鲨鱼

▲ 作者:Romain Vullo, Eberhard Frey, Christina Ifrim, Margarito A. González González, Eva S. Stinnesbeck, Wolfgang Stinnesbeck

▲ 链接:

https://science.sciencemag.org/content/371/6535/1253

▲ 摘要

现代鲨鱼占据了世界各地的海洋生态系统,但形态多样性很少,它们大多是流线型的掠食者。作者描述了一种来自晚白垩纪的鲨鱼新物种,这表明当前缺乏变异并非由于过去有限的形态学“探索”。

具体来说,这种鲨鱼(Aquilolamna milarcae)显示出许多与现代蝠鲼相似的特征,特别是细长的鳍和似乎适合滤食的嘴,这表明它是以浮游生物为食。

这一发现表明,板鳃亚目动物在进化过程中尝试了其他形式的动物,同时也表明,以浮游生物为食的“翱翔者”在这一类群中出现的时间比先前所认识的至少早了3000万年。

▲ Abstract

Modern sharks occupy marine ecosystems across the world but display little morphological diversity, being mostly streamlined predators. Vullo et al. describe a new species of shark from the late Cretaceous that shows that the lack of current variation is not due to limited morphological “exploration” in the past. Specifically, Aquilolamna milarcae displays many features similar to modern manta rays, notably long, slender fins and a mouth seemingly adapted to filter feeding, suggesting that it was planktivorous. This finding indicates both that elasmobranchs evolutionarily experimented with other forms and that the planktivorous “soarers” emerged in this group at least 30 million years earlier than previously recognized.

科学分类资讯推荐

我国第三代自主超导量子计算机,刷新纪录! - 天天要闻

我国第三代自主超导量子计算机,刷新纪录!

6月4日,记者从安徽省量子计算工程研究中心获悉,我国第三代自主超导量子计算机“本源悟空”自2024年1月6日上线运行以来,已为143个国家和地区的用户完成超50万个量子计算任务,全球访问量突破2900万次,刷新中国自主量子算力服务规模纪录,成为全球量子计算领域的重要参与者。“本源悟空”超导量子计算机。图片来源:安徽...
好消息!首个国产九价HPV疫苗获批上市 - 天天要闻

好消息!首个国产九价HPV疫苗获批上市

首个国产九价HPV疫苗获批上市记者4日从厦门大学获悉,近日,由厦门大学、翔安创新实验室夏宁邵团队和万泰生物联合研制的九价人乳头瘤病毒疫苗(大肠埃希菌)获得国家药品监督管理局批准上市。
天问二号十年之旅将带回什么 - 天天要闻

天问二号十年之旅将带回什么

2025年5月29日1时31分,长征三号乙遥一一〇运载火箭托举天问二号探测器,从西昌卫星发射中心直上苍穹。探测器精准进入预定轨道,开启了为期十年的科学探索征程。天问二号的十年太空之旅会带回什么?探索太阳系小天体又将为我国的深空探测打下哪些科
美国森林惊现六米高神秘生物!目击者再寻踪迹,引发大脚怪讨论 - 天天要闻

美国森林惊现六米高神秘生物!目击者再寻踪迹,引发大脚怪讨论

一支在科罗拉多河进行漂流探险的队伍,意外拍摄到丛林深处一个巨大直立行走的生物影像,引发了关于传说中的“大脚怪”是否真实存在的激烈讨论。事件发生于2025年5月下旬,相关视频在网络上迅速传播,引发全球关注。5月24日,由洛根·柯克担任领队的科罗拉多河漂流队正沿上科罗拉多河顺流而下。中午时分,团队约十二人靠岸休...
99.95%的黄金都藏在这里 已开始向地表泄露 - 天天要闻

99.95%的黄金都藏在这里 已开始向地表泄露

地球深处蕴藏着令人惊叹的财富。最新研究表明,地球上超过99.95%的黄金被锁定在熔融的地核中,这些贵金属正通过地质活动缓慢地向地表"泄漏"。这一惊人发现源于对夏威夷火山岩为期三年的深入分析,为理解地球内部物质循环提供了全新视角。
国能电科院银川分公司攻克火电机组调频难题 - 天天要闻

国能电科院银川分公司攻克火电机组调频难题

来源:【宁夏新闻网】宁夏新闻网讯(通讯员 丁鹏)6月3日,国能电科院银川分公司在发电企业技术攻关中取得突破性成果,其研发的一次调频综合优化技术成功将机组调频合格率从不足50%提升至85%,为保障西北电网安全稳定运行提供了创新解决方案。