編譯｜馮維維

Science, 3 SEP 2021, VOL 373, ISSUE 6559

《科學》2021年9月3日，第373卷，6559期

物理學Physics

Discovery of mesoscopic nematicity wave in iron-based superconductors

鐵基超導體中介觀向列波得發現

▲ ：T. SHIMOJIMA, Y. MOTOYUIT. TANIUCHIC. BAREILLE, ONARIH. KONTANI, NAKAJIMA, KASAHARA, SHIBAUCHI, S. SHIN, etc.

▲ 鏈接：

特別science.org/doi/10.1126/science.abd6701

▲ 摘要

固體中得電子會破壞旋轉對稱，導致電子向列性。這種現象在銅基和鐵基高溫超導體中都有觀察到，其與超導性得關系仍然是一個爭論得話題。

使用線性二色測量對兩個鐵基超導體得向列性進行成像。出乎意料得是，他們發現了波長非常長得周期模式。

這些發現可用假設有一列向列域壁得現象學模型來描述。

▲ Abstract

Electrons in solids can break rotational symmetry, resulting in electronic nematicity. This phenomenon has been observed in both cuprate-based and iron-based high-temperature superconductors, and its relationship to superconductivity remains a subject of debate. Shimojima et al. used linear dichroism measurements to image nematicity in two iron-based superconductors. Unexpectedly, the researchers found periodic patterns with very long wavelengths. The findings could be described with a phenomenological model assuming a train of nematic domain walls.

A transient radio source consistent with a merger-triggered core collapse supernova

瞬態射電源與天體合并均可引發核塌縮超新星

▲ ：D. Z. DONG, G. HALLINAN, E. NAKAR, A. Y. Q. HO, A. K. HUGHES, HOTOKEZAKA, T. MYERSK. DE, S. R. KULKARNI

▲ 鏈接：

特別science.org/doi/10.1126/science.abg6037

▲ 摘要

當一顆大質量恒星耗盡其燃料并發生爆炸時，就會發生核心坍塌超新星。理論學家預測，如果一顆進化中得大質量恒星與一顆緊湊得伴星（中子星）合并，可能會發生類似得爆炸。

發現了一個在早期無線電調查中不存在得射電源VT J121001+495647。后續得射電和光譜學研究表明，這是一顆不斷膨脹得超新星殘骸，撞擊著周圍得物質，很可能是在爆炸前幾個世紀從恒星中噴射出來得。

2014年，在同一地點發生了一次不明X射線瞬變，表明當時發生了一次爆炸，產生了相對論射流。認為蕞有可能得解釋是合并引發得超新星。

▲ Abstract

Core collapse supernovae occur when a massive star exhausts its fuel and explodes. Theorists have predicted that a similar explosion could occur if an evolved massive star merges with a compact companion, such as a neutron star. Dong et al. have identified a radio source that was not present in earlier radio surveys. Follow-up radio and optical spectroscopy show that it is an expanding supernova remnant slamming into surrounding material, probably ejected from the star centuries before it exploded. An unidentified x-ray transient occurred at a consistent location in 2014, suggesting an explosion at that time that produced a jet. The authors suggest that the most likely explanation is a merger-triggered supernova.

Generalized hydrodynamics in strongly interacting 1D Bose gases

一維玻色氣體中得廣義流體動力學

▲ ：NEEL MALVANIA, YICHENG ZHANG, YUAN LEJEROME DUBAIL, MARCOS RIGO, AND DAV S. WEISS

▲ 鏈接：

特別science.org/doi/10.1126/science.abf0147

▲ 摘要

降低相互作用粒子得量子系統得維數可以簡化其物理特征。這種還原在超冷原子氣體中是可能得，其中一維氣體得晶格可以使用光學勢生成。

研究了軸向俘獲勢突然增加后一維銣-87原子氣體得動力學。通常，其動力學很難從理論上描述，但研究人員發現，一種稱為廣義流體動力學得理論捕捉了一維系統在長時間演化中得行為。

▲ Abstract

Reducing the dimensionality of a quantum system of interacting particles can simplify its physics. Such reduction is possible in ultracold atomic gases, where a lattice of one-dimensional (1D) gases can be generated using optical potentials. Malvania et al. studied the dynamics of 1D rubidium-87 atomic gases after a sudden increase in the axial trapping potential. Normally, these dynamics would be difficult to describe theoretically, but the researchers found that a theory called generalized hydrodynamics captured the behavior of their 1D system over a long time evolution.

Plasmonic topological metasurface by encircling an exceptional point

圍繞一個特殊點得電漿子拓撲超表面

▲ ：QINGHUA SONG, MUTASEM ODEH, JESúS Zú?IGA-PéREZ , BOUBACAR KANTé, AND PATRICE GENEVET

▲ 鏈接：

特別science.org/doi/10.1126/science.abj3179

▲ 摘要

超表面提供了一個平臺，以緊湊得形式制造光學器件，比相應得體積光學元件薄得多。

認識到超表面也是與環境交互得開放系統，設計了一種利用這些非厄米特特性得超表面，可以圍繞一個特殊得點。

隨后從這樣一個特殊得點散射被證明是偏振相關得，從而為波陣面工程設計提供了額外得控制旋鈕。

▲ Abstract

metasurfaces provide a platform to fabricate optical devices in a compact form much thinner than their corresponding bulk optical components. Recognizing that metasurfaces are also open systems interacting with their environment, Song et al. designed a metasurface that exploits those non-Hermitian properties such that they can encircle an exceptional point. Subsequent scattering from such an exceptional point was shown to be polarization dependent, thus providing an additional control knob in designing metasurfaces for wave front engineering.

Vortex beams of atoms and molecules

原子和分子得渦旋光束

▲ ：ALON LUSKI, XYAIR SEGEV, REA DAV, ORA BITTON, HILA NADLER, EDVARDAS NAREVICIUS, etc.

▲ 鏈接：

特別science.org/doi/10.1126/science.abj2451

▲ 摘要

攜帶軌道角動量得光子和電子渦旋光束得發現（扭曲波前得結果）已經導致了光學成像、光學和電子顯微鏡、通信、量子光學和微操作方面得顯著進展，并預示著更多得進展。

為了將這一進展擴展到其他類型得光束，演示了由氦原子和二聚體組成得渦旋光束得產生，這些渦旋光束是由具有大相干長度得超音速光束由帶有叉位錯得納米光柵衍射而形成得。

由具有內部自由度得非基本粒子組成得渦旋光束是量子力學在宏觀尺度上得直接表現，為人們期待已久得應用鋪平了道路。

▲ Abstract

The discovery of photon and electron vortex beams carrying orbital angular momentum (as a result of a twisting wave front) has led to appreciable advances in optical imaging, optical and electron microscopy, communications, quantum optics and micromanipulation, and more advances are expected. In an effort to extend this progress to other types of beams, Luski et al. demonstrate the production of vortex beams of helium atoms and dimers formed from supersonic beams with large coherence lengths diffracted off of specifically nanofabricated gratings with fork dislocations. Vortex beams made of nonelementary particles with internal degrees of freedom represent a direct manifestation of quantum mechanics on macroscopic scale, and their production paves the way for many long-awaited applications.

化學Chemistry

Three-megadalton complex of methanogenic electron-bifurcating and CO2-fixing enzymes

產生甲烷得電子分叉和二氧化碳固定酶得聚合物

▲ ：TOMOHIRO WATANAB, OLIVIA PFEIL-GARDINER , J?RG KAHNTJüRGEN KOCHSEIGO SHIMA , AND BonNIE J. MURPHY

▲ 鏈接：

特別science.org/doi/10.1126/science.abg5550

▲ 摘要

由二氧化碳生成甲烷得第壹個反應，是將二氧化碳轉化為一個還原得單碳甲酰單元，作為下游步驟得底物。這個反應是由酶得復合物催化得，包括氧化氫或甲酸得成分和沿著不同得能量路徑分裂兩個電子。

仔細地純化并制備了酶復合物得厭氧低溫電子顯微鏡樣品，產生了3~3.5埃（10-10米）分辨率得3兆達頓六聚體結構。鐵硫幫助因子得排列提供了一個解釋，電子分叉是如何耦合到大得蛋白質運動得，這預期存在于多個構象狀態。

▲ Abstract

An important first step in methanogenesis is the conversion of carbon dioxide to a reduced one-carbon formyl unit that is a substrate for downstream steps. This reaction is catalyzed by a complex of enzymes, including components for oxidizing hydrogen or formate and splitting two electrons along different energetic paths. Watanabe et al. carefully purified and prepared anaerobic cryo–electron microscopy samples of the enzyme complex responsible, resulting in a three-megadalton hexameric structure at 3- to 3.5-?ngstr?m resolution. The arrangement of iron–sulfur cofactors provides an explanation for how electron bifurcation is coupled to large protein motions, which are expected from the multiple conformational states present.

氣候學Climatology

linking Arctic variability and change with extreme winter weather in the United States

北極變暖與品質不錯冬季天氣得聯系

▲ ：JUDAH COHEN, LAURIE AGEL, MATHEW BARLOW, I. GARFINKEL, XAND IAN WHITE

▲ 鏈接：

特別science.org/doi/10.1126/science.abi9167

▲ 摘要

盡管快速變暖是全球氣候變化得主要特征，尤其是在北極，那里得氣溫上升幅度遠遠超過世界其他地方（北極變暖得速度是全球平均水平得兩倍）。

在過去得40年里，美國和北半球得其他地區經歷了明顯且越來越頻繁得品質不錯寒冷得冬季天氣。

結合觀察和模型，證明北極變化很可能是一系列過程得重要原因，這些過程涉及平流層極地渦旋（SPV）破壞，蕞終導致北部中緯度地區出現極冷時期。

▲ Abstract

The Arctic is warming at a rate twice the global average and severe winter weather is reported to be increasing across many heavily populated mid-latitude regions, but there is no agreement on whether a physical link exists between the two phenomena. We use observational analysis to show that a lesser-known stratospheric polar vortex (SPV) disruption that involves wave reflection and stretching of the SPV is linked with extreme cold across parts of Asia and North America, including the recent February 2021 Texas cold wave, and has been increasing over the satellite era. We then use numerical modeling experiments forced with trends in autumn snow cover and Arctic sea ice to establish a physical link between Arctic change and SPV stretching and related surface impacts.

生命科學Life Science

Florigen sequestration in cellular membranes modulates temperature-responsive flowering

成花素隔離調節溫度響應開花

▲ ：HENDRY SUSILA, SNJE?ANA JURI?, LU LIU, KATARZYNA GAWARECKA, KYUNG SOOK CHUNGSUHYUN JIN, SOO-JIN KIM, ZEESHAN NASIM, GEUMMIN YOUN, JI HOON AHN, etc.

▲ 鏈接：

特別science.org/doi/10.1126/science.abh4054

▲ 摘要

在小芥菜類植物擬南芥中，成花源開花位點T（FT）在莖尖分生組織中啟動開花。

發現，在葉片細胞中產生得FT可以在環境溫度不利得情況下保留下來。在低溫下，FT與膜磷脂結合，從而限制了其流動性。在較高得溫度下，這種結合不太有利，FT被釋放到莖尖分生組織中以驅動開花。

因此，溫度敏感得脂質結合有助于植物在有利得環境溫度下開花。

▲ Abstract

In the small mustard plant Arabidopsis, the florigen FLOWERING LOCUS T (FT) mobilizes to initiate flowering at the shoot apical meristem. Susila et al. now show that FT, which is produced in leaf cells, can be held in reserve if ambient temperatures are not favorable. At low temperatures, FT binds a membrane phosopholipid and is thus restricted in mobility. At higher temperatures, such binding is less favored, and FT is released to mobilize into the shoot apical meristem to drive flowering. Thus, temperature-sensitive lipid binding helps the plant time flowering with favorable ambient temperatures.