《科學》（20240531出版）一周論文導讀

編譯 | 未玖

Science, 31 MAY 2024, VOL 384, ISSUE 6699

《科學》2024年5月31日，第384卷，6699期

材料科學Materials Science

Molecular templating of layered halide perovskite nanowires

層狀鹵化物鈣鈦礦納米線的分子模板

▲ 作者：WENHAO SHAO, JEONG HUI KIM, JEFFREY SIMON, ZHICHEN NIAN, SUNG-DOO BAEK, YUAN LU, ET AL.

▲ 鏈接：

https://www.science.org/doi/10.1126/science.adl0920

▲ 摘要：

層狀金屬鹵化物鈣鈦礦或二維鈣鈦礦可以在溶液中合成，并可通過改變組成來調節其光學和電子性質。

研究組報道了一種分子模板方法，限制了沿除[110]以外所有晶體方向的晶體生長，從而促進了一維生長。該方法廣泛適用于合成一系列具有大縱橫比和可調有機-無機化學組成的高質量層狀鈣鈦礦納米線。

這些納米線形成了非常清晰和靈活的空腔，表現出超越傳統鈣鈦礦納米線的一系列不同尋常的光學特性。研究組觀察到各向異性發射偏振、低損耗波導（低于3分貝/毫米）和有效的低閾值光放大（低于20微焦耳/平方厘米）。

▲ Abstract：

Layered metal-halide perovskites, or two-dimensional perovskites, can be synthesized in solution, and their optical and electronic properties can be tuned by changing their composition. We report a molecular templating method that restricted crystal growth along all crystallographic directions except for [110] and promoted one-dimensional growth. Our approach is widely applicable to synthesize a range of high-quality layered perovskite nanowires with large aspect ratios and tunable organic-inorganic chemical compositions. These nanowires form exceptionally well-defined and flexible cavities that exhibited a wide range of unusual optical properties beyond those of conventional perovskite nanowires. We observed anisotropic emission polarization, low-loss waveguiding (below 3 decibels per millimeter), and efficient low-threshold light amplification (below 20 microjoules per square centimeter).

A three-dimensionally architected electronic skin mimicking human mechanosensation

模擬人類機械感知的三維結構電子皮膚

▲ 作者：ZHI LIU, XIAONAN HU, RENHENG BO, YOUZHOU YANG, XU CHENG, WENBO PANG, ET AL.

▲ 鏈接：

https://www.science.org/doi/10.1126/science.adk5556

▲ 摘要：

人體皮膚對機械刺激的感知源于將外力轉化為電信號的機械感受器的傳導。雖然模仿這些機械感受器的空間分布可使電子皮膚的發展能夠解耦傳感法向力/剪切力和應變，但其仍難以捉摸。

研究組報道了一種三維（3D）結構的電子皮膚（稱為3DAE皮膚），其力和應變傳感組件以3D布局排列，模仿人類皮膚中的默克爾細胞和魯菲尼氏小體。

這種3DAE皮膚具有優異的法向力、剪切力和應變解耦傳感性能，可用于開發觸覺系統，通過觸摸同時測量物體的模量/曲率。演示包括對各種形狀和新鮮度的水果、面包和蛋糕進行快速模量測量。

▲ Abstract：

Human skin sensing of mechanical stimuli originates from transduction of mechanoreceptors that converts external forces into electrical signals. Although imitating the spatial distribution of those mechanoreceptors can enable developments of electronic skins capable of decoupled sensing of normal/shear forces and strains, it remains elusive. We report a three-dimensionally (3D) architected electronic skin (denoted as 3DAE-Skin) with force and strain sensing components arranged in a 3D layout that mimics that of Merkel cells and Ruffini endings in human skin. This 3DAE-Skin shows excellent decoupled sensing performances of normal force, shear force, and strain and enables development of a tactile system for simultaneous modulus/curvature measurements of an object through touch. Demonstrations include rapid modulus measurements of fruits, bread, and cake with various shapes and degrees of freshness.

Spontaneous weathering of natural minerals in charged water microdroplets forms nanomaterials

天然礦物質在帶電水微滴中自然風化形成納米材料

▲ 作者：B. K. SPOORTHI, KOYENDRILA DEBNATH, PALLAB BASURI, ANKIT NAGAR, UMESH V. WAGHMARE AND THALAPPIL PRADEEP

▲ 鏈接：

https://www.science.org/doi/10.1126/science.adl3364

▲ 摘要：

在這項工作中，研究組展示了常見礦物質顆粒在幾毫秒內自發分解，在帶電的水微滴中形成納米顆粒。他們將石英和紅寶石等微米級天然礦物整合到通過電噴霧產生的水性微滴中，將其轉化為5至10納米的顆粒。將液滴沉積在基底上，從而實現納米顆粒表征。

研究組通過模擬確定，石英經歷了質子誘導滑移，特別是當尺寸縮小并暴露在電場中時。這導致顆粒分裂和硅酸鹽碎片的形成，質譜分析證實了這一點。考慮到大氣中帶電氣溶膠的普遍存在，這種快速風化過程可能對土壤形成至關重要。

▲ Abstract：

In this work, we show that particles of common minerals break down spontaneously to form nanoparticles in charged water microdroplets within milliseconds. We transformed micron-sized natural minerals like quartz and ruby into 5- to 10-nanometer particles when integrated into aqueous microdroplets generated via electrospray. We deposited the droplets on a substrate, which allowed nanoparticle characterization. We determined through simulations that quartz undergoes proton-induced slip, especially when reduced in size and exposed to an electric field. This leads to particle scission and the formation of silicate fragments, which we confirmed with mass spectrometry. This rapid weathering process may be important for soil formation, given the prevalence of charged aerosols in the atmosphere.

Shearing brittle intermetallics enhances cryogenic strength and ductility of steels

剪切脆性金屬間化合物提高鋼的低溫強度和塑性

▲ 作者：FENG WANG, MIAO SONG, MOHAMED N. ELKOT, NING YAO, BINHAN SUN, MIN SONG, ET AL.

▲ 鏈接：

https://www.science.org/doi/10.1126/science.ado2919

▲ 摘要：

沉淀物對于制造機械強度高的金屬材料至關重要。在這項工作中，研究組報道了B2相（有序體心立方）納米沉淀（通常被認為是不可剪切的金屬間化合物）在低溫拉伸載荷過程中在輕質復合鋼中的位錯切割。

由于亞納米尺度局部化學有序區的顯著強化和基體中多主元素明顯的固溶強化，奧氏體基體中位錯滑移的高強度水平實現了剪切。這種機制不僅利用了原本難以穿透的脆性納米沉淀物所提供的強烈強化和應變硬化，而且還通過其連續剪切和持續變形引入了塑性。

因此，這種鋼材展示了超高的低溫拉伸強度，高達2吉帕，拉伸伸長率達到34%。這項研究揭示了一種設計高性能結構材料的新策略。

▲ Abstract：

Precipitates are crucial for crafting mechanically strong metallic materials. In this work, we report the dislocation cutting of B2 (ordered body-centered cubic) nanoprecipitates, typically considered nonshearable intermetallics, in a lightweight compositionally complex steel during cryogenic tensile loading. Shearing is enabled by the high strength level for dislocation glide within the austenitic matrix, attributed to the substantial strengthening from subnanoscale local chemical ordering zones and the pronounced solid solution strengthening from the multiprincipal elements in the matrix. This mechanism not only harnesses the intense strengthening and strain hardening provided by otherwise impenetrable brittle nanoprecipitates but also introduces ductility through their sequential shearing with ongoing deformation. Our steel thus showcases ultrahigh cryogenic tensile strength up to 2 gigapascal at a remarkable tensile elongation of 34%. This study reveals a new strategy for designing high-performance structural materials.

地球科學Earth Science

Heinrich event ice discharge and the fate of the Atlantic Meridional Overturning Circulation

海因里希事件冰排放與大西洋經向翻轉環流的命運

▲ 作者：YUXIN ZHOU AND JERRY F. MCMANUS

▲ 鏈接：

https://www.science.org/doi/10.1126/science.adh8369

▲ 摘要：

在海因里希事件期間，巨大的冰山“艦隊”偶爾淹沒北大西洋，削弱了翻轉環流。這些事件的冰排放限制了翻轉環流對冰山融化的敏感性。

研究組重建了海因里希事件4期間的這些冰排放，發現其高達0.13 Sv（1 Sv = 100萬立方米每秒），而在所有事件中平均值僅為0.029 Sv。如今格陵蘭冰蓋的冰山崩解與中等規模海因里希事件相當。

隨著未來格陵蘭冰蓋從海洋終點出口消退，僅冰山崩解尚不足以對大西洋翻轉環流造成災難性破壞，其可能不會持續足夠長的時間，盡管加速的格陵蘭徑流和持續的全球變暖仍然威脅著環流的穩定性。

▲ Abstract：

During Heinrich events, great armadas of icebergs episodically flooded the North Atlantic Ocean and weakened overturning circulation. The ice discharges of these episodes constrain the sensitivity of overturning circulation to iceberg melting. We reconstructed these ice discharges to be as high as 0.13 sverdrup (Sv) (1 Sv = 1 million cubic meters per second) during Heinrich event 4 and to average 0.029 Sv over all episodes. The present-day Greenland Ice Sheet calving of icebergs is comparable to that of a mid-range Heinrich event. As the future Greenland Ice Sheet recedes from marine-terminating outlets, its iceberg calving likely will not persist long enough for icebergs alone to cause catastrophic disruption to the Atlantic overturning circulation, although the accelerating Greenland runoff and continued global warming remain threats to the circulation stability.

社會學Sociology

Supersharers of fake news on Twitter

推特上的假新聞超級分享者

▲ 作者：SAHAR BARIBI-BARTOV, BRIONY SWIRE-THOMPSON AND NIR GRINBERG

▲ 鏈接：

https://www.science.org/doi/10.1126/science.adl4435

▲ 摘要：

政府或許有能力讓假新聞充斥社交媒體，但普通選民如何使用這些泛濫的假新聞卻鮮為人知。

在這項工作中，研究組確定了2107名登記的美國選民，2020年美國總統大選期間，他們在由664391名選民組成的整個群組中在Twitter上分享了80%的假新聞。結果發現超級分享者是該網絡的重要成員，在該平臺注冊選民中占比高達5.2%。

超級分享者中女性、老年人和注冊共和黨人的比例明顯過高。超級分享者的巨大流量似乎并非自動產生，而是通過人工和持續轉發產生的。這些發現凸顯了社交媒體對民主的脆弱性，在社交媒體上，一小群人歪曲了許多人的政治現實。

▲ Abstract：

Governments may have the capacity to flood social media with fake news, but little is known about the use of flooding by ordinary voters. In this work, we identify 2107 registered US voters who account for 80% of the fake news shared on Twitter during the 2020 US presidential election by an entire panel of 664391 voters. We found that supersharers were important members of the network, reaching a sizable 5.2% of registered voters on the platform. Supersharers had a significant overrepresentation of women, older adults, and registered Republicans. Supersharers’ massive volume did not seem automated but was rather generated through manual and persistent retweeting. These findings highlight a vulnerability of social media for democracy, where a small group of people distort the political reality for many.