《科學》(20210319出版)一周論文導讀

2021年03月22日02:45:02 科學 1067

編譯|馮維維


Science, 19 March 2021 Vol 371, Issue 6535

《科學》2021年3月19日,第371卷6535期

《科學》(20210319出版)一周論文導讀 - 天天要聞


物理學Physics


Generating arbitrary topological windings of a non-Hermitian band

開放的拓撲

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

▲ 鏈接:

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

▲ 摘要

控制系統的拓撲結構提供了一條路線來開發抗缺陷的魯棒的設備。雖然早期的拓撲帶理論發展集中在厄米特(封閉)系統上,但最近的努力已轉向非厄米特(開放)系統。

作者報告了非厄密能帶的拓撲非平凡繞組的測量和控制。通過在已調製的環形諧振器中實現由光學頻率模構成的頻率合成維上的非厄米特晶格哈密頓量,他們直接可視化了非平凡拓撲帶繞組,並證明了該繞組是可以控制的。

這種控制為開放物理系統中拓撲非平凡相的實驗合成、表徵和控制提供了一條途徑。

▲ 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

調節扭曲雙層石墨烯中電子相關性

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

▲ 鏈接:

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

▲ 摘要

要在扭曲雙分子層石墨烯(MATBG)中解釋超導狀態的性質被證明很棘手。為了研究電子-電子關聯在這種狀態下的作用,作者在MATBG樣品附近放置了另一層石墨烯雙分子層,這一層採用了傳統的石墨烯薄片排列方式。

通過改變傳統雙層膜中的載流子密度,研究人員控制了MATBG中的相互作用強度。減弱相互作用會增強超導性,這與電子-聲子耦合與庫侖相互作用競爭以穩定超導相的情況一致。

▲ 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.


化學Chemistry

Detection of two interstellar polycyclic aromatic hydrocarbons via spectral matched filtering

星際多環芳烴的識別

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

▲ 鏈接:

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

▲ 摘要

中紅外光譜分析表明,多環芳烴(PAHs)大量存在於許多天體中,但該技術無法確定具體存在的多環芳烴分子。如果分子足夠豐富且偶極矩很大,射電天文學可以提供單獨的鑒定,但多環芳烴預計會產生大量非常弱的線。

作者對位於金牛座星際分子雲內的TMC-1進行了疊加和匹配過濾分析,在射電觀測中尋找多環芳烴。他們鑒定了小的多環芳烴氰基萘的兩個同分異構體,兩個連接著CN基團的苯環。

▲ 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

▲ 鏈接:

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

▲ 摘要

丙烷氧化脫氫制丙烯和水的催化劑的選擇性隨著轉化率的增加而降低,因為丙烯本身比丙烷更容易被氧化。

作者通過在丙烷脫氫催化劑上生長一種選擇性氫燃燒催化劑氧化銦(一種約2納米的外殼),並將鉑納米顆粒支撐在氧化鋁球上,從而創造了納米級串聯催化劑。這種塗層使鉑納米顆粒暴露,以便丙烷脫氫。

在氧化銦-鉑界面處,表面氫原子被氧化。這種方法使丙烯的產量提高到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%.


地球科學Earth sciences

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

平流層煙霧可解釋破紀錄氣溶膠含量

▲ 作者:Eitan Hirsch, Ilan Koren

▲ 鏈接:

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

▲ 摘要

2020年,澳大利亞大規模的森林大火向平流層排放了大量煙霧。赫希和科倫發現,這種煙霧在南半球造成了破紀錄的懸浮顆粒水平,其程度堪比一次中度火山爆發。

造成這種嚴重程度的原因是火災的強度及其所處緯度的對流層頂較淺和中緯度氣旋帶。這種氣溶膠的增加導致了海洋無雲地區的大量降溫。

▲ 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

恐龍時代的浮游食性鯊魚

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

▲ 鏈接:

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

▲ 摘要

現代鯊魚佔據了世界各地的海洋生態系統,但形態多樣性很少,它們大多是流線型的掠食者。作者描述了一種來自晚白堊紀的鯊魚新物種,這表明當前缺乏變異並非由於過去有限的形態學「探索」。

具體來說,這種鯊魚(Aquilolamna milarcae)顯示出許多與現代蝠鱝相似的特徵,特別是細長的鰭和似乎適合濾食的嘴,這表明它是以浮游生物為食。

這一發現表明,板鰓亞目動物在進化過程中嘗試了其他形式的動物,同時也表明,以浮游生物為食的「翱翔者」在這一類群中出現的時間比先前所認識的至少早了3000萬年。

▲ 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.

科學分類資訊推薦

我國第三代自主超導量子計算機,刷新紀錄! - 天天要聞

我國第三代自主超導量子計算機,刷新紀錄!

6月4日,記者從安徽省量子計算工程研究中心獲悉,我國第三代自主超導量子計算機「本源悟空」自2024年1月6日上線運行以來,已為143個國家和地區的用戶完成超50萬個量子計算任務,全球訪問量突破2900萬次,刷新中國自主量子算力服務規模紀錄,成為全球量子計算領域的重要參與者。「本源悟空」超導量子計算機。圖片來源:安徽...
好消息!首個國產九價HPV疫苗獲批上市 - 天天要聞

好消息!首個國產九價HPV疫苗獲批上市

首個國產九價HPV疫苗獲批上市記者4日從廈門大學獲悉,近日,由廈門大學、翔安創新實驗室夏寧邵團隊和萬泰生物聯合研製的九價人乳頭瘤病毒疫苗(大腸埃希菌)獲得國家藥品監督管理局批准上市。
天問二號十年之旅將帶回什麼 - 天天要聞

天問二號十年之旅將帶回什麼

2025年5月29日1時31分,長征三號乙遙一一〇運載火箭托舉天問二號探測器,從西昌衛星發射中心直上蒼穹。探測器精準進入預定軌道,開啟了為期十年的科學探索征程。天問二號的十年太空之旅會帶回什麼?探索太陽系小天體又將為我國的深空探測打下哪些科
美國森林驚現六米高神秘生物!目擊者再尋蹤跡,引發大腳怪討論 - 天天要聞

美國森林驚現六米高神秘生物!目擊者再尋蹤跡,引發大腳怪討論

一支在科羅拉多河進行漂流探險的隊伍,意外拍攝到叢林深處一個巨大直立行走的生物影像,引發了關於傳說中的「大腳怪」是否真實存在的激烈討論。事件發生於2025年5月下旬,相關視頻在網路上迅速傳播,引發全球關注。5月24日,由洛根·柯克擔任領隊的科羅拉多河漂流隊正沿上科羅拉多河順流而下。中午時分,團隊約十二人靠岸休...
99.95%的黃金都藏在這裡 已開始向地表泄露 - 天天要聞

99.95%的黃金都藏在這裡 已開始向地表泄露

地球深處蘊藏著令人驚嘆的財富。最新研究表明,地球上超過99.95%的黃金被鎖定在熔融的地核中,這些貴金屬正通過地質活動緩慢地向地表"泄漏"。這一驚人發現源於對夏威夷火山岩為期三年的深入分析,為理解地球內部物質循環提供了全新視角。
國能電科院銀川分公司攻克火電機組調頻難題 - 天天要聞

國能電科院銀川分公司攻克火電機組調頻難題

來源:【寧夏新聞網】寧夏新聞網訊(通訊員 丁鵬)6月3日,國能電科院銀川分公司在發電企業技術攻關中取得突破性成果,其研發的一次調頻綜合優化技術成功將機組調頻合格率從不足50%提升至85%,為保障西北電網安全穩定運行提供了創新解決方案。