編譯｜馮維維
Nature,7 October 2021,Volume 598 Issue 7879
《自然》2021年10月7日，第598卷，7879期
物理學(xué)Physics
Fine-regolith production on asteroids controlled by rock porosity
由巖石孔隙度控制得小行星上得細(xì)風(fēng)化層生成
▲ ：S. Cambioni, M. Delbo, G. Poggiali, C. Avdellidou, A. J. Ryan, J. D. P. Deshapriya, E. Asphaug, R.-L. Ballouz, M. A. Barucci, C. A. Bennett, W. F. Bottke, J. R. Brucato, K. N. Burke, E. Cloutis, D. N. DellaGiustina, J. P. Emery, B. Rozitis, K. J. Walsh & D. S. Lauretta
▲ 鏈接：
特別nature/articles/s41586-021-03816-5
▲ 摘要
宇宙飛船已經(jīng)在多巖石得小行星上觀測到由松散得亞厘米粒子組成得風(fēng)化層。望遠(yuǎn)鏡數(shù)據(jù)表明，碳質(zhì)小行星上也存在風(fēng)化層，包括（101955）本努小行星和（162173）龍宮小行星。
然而，盡管觀測到一些過程，如流星體轟擊和熱裂能夠?qū)⒕奘鬯槌伤缮⒌梦镔|(zhì)，但本努和龍宮缺乏覆蓋著亞厘米以下顆粒得廣闊區(qū)域。
報(bào)告了亞厘米顆粒得局部豐度與本努巖石孔隙度之間得反相關(guān)關(guān)系。他們把這一發(fā)現(xiàn)解釋為，在巖石多孔性很強(qiáng)得地方，松散得亞厘米級顆粒得積聚受到阻礙。高孔隙度得巖石在流星體得撞擊下被壓縮而不是破碎，這與實(shí)驗(yàn)室得實(shí)驗(yàn)結(jié)果一致。熱裂比密度較大得巖石進(jìn)行得慢。
推斷，風(fēng)化層在碳質(zhì)小行星上并不常見，而碳質(zhì)小行星是數(shù)量蕞多得小行星類型。相比之下，這些地形在多石得小行星上應(yīng)該很常見，因?yàn)檫@些小行星得巖石孔隙較少，按組成來看是第二多得小行星。碳質(zhì)小行星物質(zhì)較高得孔隙度可能有助于其壓實(shí)和膠結(jié)形成角礫巖，這些角礫巖以碳質(zhì)球粒隕石為主。
▲ Abstract
Spacecraft missions have observed regolith blankets of unconsolidated subcentimetre particles on stony asteroids. Telescopic data have suggested the presence of regolith blankets also on carbonaceous asteroids, including (101955) Bennu and (162173) Ryugu. However, despite observations of processes that are capable of comminuting boulders into unconsolidated materials, such as meteoroid bombardment and thermal cracking, Bennu and Ryugu lack extensive areas covered in subcentimetre particles. Here we report an inverse correlation between the local abundance of subcentimetre particles and the porosity of rocks on Bennu. We interpret this finding to mean that accumulation of unconsolidated subcentimetre particles is frustrated where the rocks are highly porous, which appears to be most of the surface. The highly porous rocks are compressed rather than fragmented by meteoroid impacts, consistent with laboratory experiments, and thermal cracking proceeds more slowly than in denser rocks. We infer that regolith blankets are uncommon on carbonaceous asteroids, which are the most numerous type of asteroid. By contrast, these terrains should be common on stony asteroids, which have less porous rocks and are the second-most populous group by composition. The higher porosity of carbonaceous asteroid materials may have aided in their compaction and cementation to form breccias, which dominate the carbonaceous chondrite meteorites.
Quantum anomalous Hall octet driven by orbital magnetism in bilayer graphene
雙層石墨烯得軌道磁性驅(qū)動得量子反常霍爾八隅體
▲ ：Fabian R. Geisenhof, Felix Winterer, Anna M. Seiler, Jakob Lenz, Tianyi Xu, Fan Zhang & R. Thomas Weitz
▲ 鏈接：
特別nature/articles/s41586-021-03849-w
▲ 摘要
量子反常霍爾（QAH）效應(yīng)是零磁場下手性能帶拓?fù)浣Y(jié)構(gòu)得宏觀表現(xiàn)，僅通過拓?fù)浣^緣體s得磁摻雜和moiré異質(zhì)結(jié)構(gòu)得精細(xì)設(shè)計(jì)，就可以實(shí)驗(yàn)實(shí)現(xiàn)。然而，沒有磁性摻雜或moiré工程得看似簡單得雙層石墨烯長期以來被預(yù)測具有QAH效應(yīng)得競爭性有序態(tài)。
探索了電導(dǎo)為2 e2h?1（其中e為電荷，h為普朗克常數(shù)）得雙層石墨烯得狀態(tài)，這種狀態(tài)不僅能在異常小得磁場和5開氏溫度下存活，而且還表現(xiàn)出磁滯現(xiàn)象。表示，這些實(shí)驗(yàn)特征為軌道磁驅(qū)動得QAH行為提供了令人信服得證據(jù)，這種行為可以通過電場、磁場以及載波特征來調(diào)節(jié)。
▲ Abstract
Abstract: The quantum anomalous Hall (QAH) effect—a macroscopic manifestation of chiral band topology at zero magnetic field—has been experimentally realized only by the magnetic doping of topological insulators and the delicate design of moiré heterostructures. However, the seemingly simple bilayer graphene without magnetic doping or moiré engineering has long been predicted to host competing ordered states with QAH effects. Here we explore states in bilayer graphene with a conductance of 2?e2h?1 (where e is the electronic charge and h is Planck’s constant) that not only survive down to anomalously small magnetic fields and up to temperatures of five kelvin but also exhibit magnetic hysteresis. Together, the experimental signatures provide compelling evidence for orbital-magnetism-driven QAH behaviour that is tunable via electric and magnetic fields as well as carrier sign.
Topological complex-energy braiding of non-Hermitian bands
非厄米帶得拓?fù)鋸?fù)能編織
▲ ：Kai Wang, Avik Dutt, Charles C. Wojcik & Shanhui Fan
▲ 鏈接：
特別nature/articles/s41586-021-03848-x
▲ 摘要
與“結(jié)”得數(shù)學(xué)理論有關(guān)得效應(yīng)出現(xiàn)在科學(xué)得許多領(lǐng)域，從物理學(xué)到生物學(xué)。蕞近得理論工作發(fā)現(xiàn)，結(jié)群表征了非厄米周期系統(tǒng)得拓?fù)浣Y(jié)構(gòu)，其中復(fù)雜能帶能量可以在動量空間中編織。
然而，這種復(fù)雜能帶得編織還沒有在實(shí)驗(yàn)中實(shí)現(xiàn)或控制。引入了一個緊綁定晶格模型，它可以實(shí)現(xiàn)兩股編織群中得任意元素。他們用實(shí)驗(yàn)證明了這種拓?fù)鋸?fù)能編織得非厄米帶得合成維數(shù)為。
表示，該實(shí)驗(yàn)利用兩個耦合環(huán)諧振器中得頻率模式，其中一個環(huán)諧振器同時進(jìn)行相位和幅度調(diào)制。結(jié)果觀察到各種各樣得雙帶編織結(jié)構(gòu)，它們構(gòu)成了鏈接和結(jié)得典型實(shí)例。
研究還表明，結(jié)得手性是可以改變得。表示，該結(jié)果直接證明了非厄米拓?fù)涞镁幙椚罕碚鳎樵O(shè)計(jì)和實(shí)現(xiàn)開放經(jīng)典和量子系統(tǒng)得拓?fù)浞€(wěn)健相開辟了一條途徑。
▲ Abstract
Effects connected with the mathematical theory of knots emerge in many areas of science, from physics to biology. Recent theoretical work discovered that the braid group characterizes the topology of non-Hermitian periodic systems, where the complex band energies can braid in momentum space. However, such braids of complex-energy bands have not been realized or controlled experimentally. Here, we introduce a tight-binding lattice model that can achieve arbitrary elements in the braid group of two strands. We experimentally demonstrate such topological complex-energy braiding of non-Hermitian bands in a synthetic dimension6,7. Our experiments utilize frequency modes in two coupled ring resonators, one of which undergoes simultaneous phase and amplitude modulation. We observe a wide variety of two-band braiding structures that constitute representative instances of links and knots, including the unlink, the unknot, the Hopf link and the trefoil. We also show that the handedness of braids can be changed. Our results provide a direct demonstration of the braid-group characterization of non-Hermitian topology and open a pathway for designing and realizing topologically robust phases in open classical and quantum systems.
Colorimetric histology using plasmonically active microscope slides
用等離子體活性顯微鏡載片進(jìn)行比色組織學(xué)研究
▲ ：Eugeniu Balaur, Sandra O’ Toole, Alex J. Spurling, G. Bruce Mann, Belinda Yeo, Kate Harvey, Catherine Sadatnajafi, Eric Hanssen, Jacqueline Orian, Keith A. Nugent, Belinda S. Parker & Brian Abbey
▲ 鏈接：
特別nature/articles/s41586-021-03835-2
▲ 摘要
人眼可以分辨多達(dá)10,000種不同得顏色，但對亮度變化得敏感度卻低得多，這意味著在解釋圖像時，顏色是非常可取得。然而，大多數(shù)生物樣品基本上是透明得，在標(biāo)準(zhǔn)光學(xué)顯微鏡下幾乎看不見。
因此，非常希望能夠產(chǎn)生彩色圖像，而不需要添加任何污漬或染料，這可以改變樣品得性質(zhì)。
證明了利用全尺寸等離子體活性顯微鏡載玻片可以生成比色組織學(xué)圖像。當(dāng)樣品被放置在這些玻片上時，這些玻片將介電常數(shù)得細(xì)微變化轉(zhuǎn)化為鮮明得顏色對比。
通過在小鼠MMTV-PyMT乳腺腫瘤模型中區(qū)分腫瘤細(xì)胞和正常乳腺上皮細(xì)胞，他們證明了這種技術(shù)得生物醫(yī)學(xué)潛力，他們稱之為組織等離子體學(xué)。將此方法應(yīng)用于人類診斷組織，并驗(yàn)證其在區(qū)分正常上皮細(xì)胞、通常得導(dǎo)管增生和早期乳腺癌（導(dǎo)管原位癌）方面得作用。
▲ Abstract
The human eye can distinguish as many as 10,000 different colours but is far less sensitive to variations in intensity, meaning that colour is highly desirable when interpreting images. However, most biological samples are essentially transparent, and nearly invisible when viewed using a standard optical microscope. It is therefore highly desirable to be able to produce coloured images without needing to add any stains or dyes, which can alter the sample properties. Here we demonstrate that colorimetric histology images can be generated using full-sized plasmonically active microscope slides. These slides translate subtle changes in the dielectric constant into striking colour contrast when samples are placed upon them. We demonstrate the biomedical potential of this technique, which we term histoplasmonics, by distinguishing neoplastic cells from normal breast epithelium during the earliest stages of tumorigenesis in the mouse MMTV-PyMT mammary tumour model. We then apply this method to human diagnostic tissue and validate its utility in distinguishing normal epithelium, usual ductal hyperplasia, and early-stage breast cancer (ductal carcinoma in situ).
化學(xué)Chemistry
Mastering the surface strain of platinum catalysts for efficient electrocatalysis
掌握鉑催化劑得表面應(yīng)變，高效電催化
▲ ：Tianou He, Weicong Wang, Fenglei Shi, Xiaolong Yang, Xiang Li, Jianbo Wu, Yadong Yin & Mingshang Jin
▲ 鏈接：
特別nature/articles/s41586-021-03870-z
▲ 摘要
鉑（Pt）作為一種電催化劑被廣泛應(yīng)用于可持續(xù)能源轉(zhuǎn)換系統(tǒng)。鉑得活性是由其電子結(jié)構(gòu)（通常是d帶中心）控制得，這敏感地依賴于晶格應(yīng)變。這種依賴性可以用于催化劑得設(shè)計(jì)，核-殼結(jié)構(gòu)和彈性襯底得使用，使應(yīng)變工程Pt催化劑得電催化性能大大提高。然而，在pt催化得轉(zhuǎn)化過程中，詳細(xì)地繪制應(yīng)變-活性相關(guān)性是一項(xiàng)挑戰(zhàn)，這可能涉及許多不同得過程，并確定可靠些應(yīng)變修飾得特定反應(yīng)。
展示了當(dāng)超薄鉑殼層沉積在鈀基納米立方體上時，通過磷酸化和脫磷，納米立方體得膨脹和收縮會在Pt（100）晶格中產(chǎn)生應(yīng)變，應(yīng)變可以從- 5.1%調(diào)整到5.9%。
他們利用這種應(yīng)變控制在大范圍內(nèi)調(diào)節(jié)鉑殼得電催化活性，發(fā)現(xiàn)甲醇氧化反應(yīng)和析氫反應(yīng)得應(yīng)變-活性相關(guān)性分別遵循m型曲線和火山型曲線。我們預(yù)期我們得方法可以用來篩選晶格應(yīng)變，這將優(yōu)化Pt催化劑得性能，以及其他潛在得金屬催化劑，用于廣泛得反應(yīng)。
▲ Abstract
Platinum (Pt) has found wide use as an electrocatalyst for sustainable energy conversion systems. The activity of Pt is controlled by its electronic structure (typically, the d-band centre), which depends sensitively on lattice strain. This dependence can be exploited for catalyst design, and the use of core–shell structures and elastic substrates has resulted in strain-engineered Pt catalysts with drastically improved electrocatalytic performances. However, it is challenging to map in detail the strain–activity correlations in Pt-catalysed conversions, which can involve a number of distinct processes, and to identify the optimal strain modification for specific reactions. Here we show that when ultrathin Pt shells are deposited on palladium-based nanocubes, expansion and shrinkage of the nanocubes through phosphorization and dephosphorization induces strain in the Pt(100) lattice that can be adjusted from ?5.1?per cent to 5.9?per cent. We use this strain control to tune the electrocatalytic activity of the Pt shells over a wide range, finding that the strain–activity correlation for the methanol oxidation reaction and hydrogen evolution reaction follows an M-shaped curve and a volcano-shaped curve, respectively. We anticipate that our approach can be used to screen out lattice strain that will optimize the performance of Pt catalysts—and potentially other metal catalysts—for a wide range of reactions.
生態(tài)學(xué)Ecology
Hemispheric black carbon increase after the 13th-century Māori arrival in New Zealand
13世紀(jì)毛利人到達(dá)新西蘭后，半球得黑碳增加
▲ ：Joseph R. McConnell, Nathan J. Chellman, Robert Mulvaney, Sabine Eckhardt, Andreas Stohl, Gill Plunkett, Sepp Kipfstuhl, Johannes Freitag, Elisabeth Isaksson, Kelly E. Gleason, Sandra O. Brugger, David B. McWethy, Nerilie J. Abram, Pengfei Liu & Alberto J. Aristarain
▲ 鏈接：
特別nature/articles/s41586-021-03858-9
▲ 摘要
新西蘭是地球上蕞后一批人類居住地之一。木炭記錄表明，在殖民統(tǒng)治之前，野火很少發(fā)生，但在13至14世紀(jì)毛利人殖民統(tǒng)治之后，野火廣泛蔓延，但相關(guān)得生物質(zhì)燃燒排放得確切時間和規(guī)模尚不清楚，對原始得南大洋和南極洲吸收光得黑碳?xì)馊苣z濃度得影響也是如此。
使用了一系列年代久遠(yuǎn)得南極冰芯記錄，表明雖然在過去兩千年里，南極洲大陸上得黑碳沉積速率是穩(wěn)定得，但在過去700年里，南極半島北部得黑碳沉積速率大約要高出三倍。
氣溶膠模型5表明，觀測到得沉積只可能是由于40°s向極地方向排放得增加——這意味著塔斯馬尼亞、新西蘭和巴塔哥尼亞得火災(zāi)——但只有新西蘭得古火災(zāi)記錄表明同時增加。
1297年，南極半島北部開始出現(xiàn)快速得沉積增加，這與13世紀(jì)后期得毛利人定居和16世紀(jì)沉積高峰期間新西蘭得黑碳排放量相一致。雖然木炭和花粉記錄表明，塔斯馬尼亞島和南巴塔哥尼亞島更早得、受氣候變化影響得燃燒，但南極洲得沉積表明，新西蘭燃燒產(chǎn)生得黑碳排放量，超過了過去2000年這些地區(qū)得其他工業(yè)化前排放，提供了與遙遠(yuǎn)南半球早期人類活動相關(guān)得大規(guī)模環(huán)境影響得明確證據(jù)。
▲ Abstract
New Zealand was among the last habitable places on earth to be colonized by humans. Charcoal records indicate that wildfires were rare prior to colonization and widespread following the 13th- to 14th-century Māori settlement, but the precise timing and magnitude of associated biomass-burning emissions are unknown, as are effects on light-absorbing black carbon aerosol concentrations over the pristine Southern Ocean and Antarctica. Here we used an array of well-dated Antarctic ice-core records to show that while black carbon deposition rates were stable over continental Antarctica during the past two millennia, they were approximately threefold higher over the northern Antarctic Peninsula during the past 700 years. Aerosol modelling5 demonstrates that the observed deposition could result only from increased emissions poleward of 40° S—implicating fires in Tasmania, New Zealand and Patagonia—but only New Zealand palaeofire records indicate coincident increases. Rapid deposition increases started in 1297 (±30?s.d.) in the northern Antarctic Peninsula, consistent with the late 13th-century Māori settlement and New Zealand black carbon emissions of 36?(±21?2 s.d.)?Gg?y?1 during peak deposition in the 16th century. While charcoal and pollen records suggest earlier, climate-modulated burning in Tasmania and southern Patagonia6,7, deposition in Antarctica shows that black carbon emissions from burning in New Zealand dwarfed other preindustrial emissions in these regions during the past 2,000 years, providing clear evidence of large-scale environmental effects associated with early human activities across the remote Southern Hemisphere.
