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发布日期：2024-07-15 作者：开云
Science, 31 MAY 2024, VOL 384, ISSUE 6699
《科学》2024年5月31日，第384卷，6699期
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材料科学Materials Science
Molecular templating of layered halide perovskite nanowires
层状卤化物钙钛矿纳米线的份子模板
▲ 作者：WENHAO SHAO, JEONG HUI KIM, JEFFREY SIMON, ZHICHEN NIAN, SUNG-DOO BAEK, YUAN LU, ET AL.
▲ 链接：
https://www.science.org/doi/10.1126/science.adl0920
▲ 摘要：
层状金属卤化物钙钛矿或二维钙钛矿可以在溶液中合成，并可经由过程改变构成来调理其光学和电子性质。
研究组报导了一种份子模板方式，限制了沿除[110]之外所有晶体标的目的的晶体发展，从而增进了一维发展。该方式普遍合用在合成一系列具有年夜纵横比和可调有机-无机化学构成的高质量层状钙钛矿纳米线。
这些纳米线构成了很是清楚和矫捷的空腔，表示出超出传统钙钛矿纳米线的一系列分歧平常的光学特征。研究组不雅察到各向异性发射偏振、低消耗波导（低在3分贝/毫米）和有用的低阈值光放年夜（低在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
摹拟人类机械感知的三维布局电子皮肤
▲ 作者：ZHI LIU, XIAONAN HU, RENHENG BO, YOUZHOU YANG, XU CHENG, WENBO PANG, ET AL.
▲ 链接：
https://www.science.org/doi/10.1126/science.adk5556
▲ 摘要：
人体皮肤对机械刺激的感知源在将外力转化为电旌旗灯号的机械感触感染器的传导。固然模拟这些机械感触感染器的空间散布可以使电子皮肤的成长可以或许解耦传感法向力/剪切力和应变，但其仍难以捉摸。
研究组报导了一种三维（3D）布局的电子皮肤（称为3DAE皮肤），其力和应变传感组件以3D结构摆列，模拟人类皮肤中的默克尔细胞和鲁菲尼氏小体。
这类3DAE皮肤具有优良的法向力、剪切力和应变解耦传感机能，可用在开辟触觉系统，经由过程触摸同时丈量物体的模量/曲率。演示包罗对各类外形和新颖度的生果、面包和蛋糕进行快速模量丈量。
▲ 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
自然矿物资在带电水微滴中天然风化构成纳米材料
▲ 作者：B. K. SPOORTHI, KOYENDRILA DEBNATH, PALLAB BASURI, ANKIT NAGAR, UMESH V. WAGHMARE AND THALAPPIL PRADEEP
▲ 链接：
https://www.science.org/doi/10.1126/science.adl3364
▲ 摘要：
在这项工作中，研究组展现了常见矿物资颗粒在几毫秒内自觉分化，在带电的水微滴中构成纳米颗粒。他们将石英和红宝石等微米级自然矿物整合到经由过程电喷雾发生的水性微滴中，将其转化为5至10纳米的颗粒。将液滴沉积在基底上，从而实现纳米颗粒表征。
研究组经由过程摹拟肯定，石英履历了质子引诱滑移，特殊是当尺寸缩小并表露在电场中时。这致使颗粒割裂和硅酸盐碎片的构成，质谱阐发证实了这一点。斟酌到年夜气中带电气溶胶的遍及存在，这类快速风化进程可能对泥土构成相当主要。
▲ Abstract：
In this work, we show that particles of common minerals break down spontaneously to form nanoparticles in charged wat开云体育apper 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
剪切脆性金属间化合物提高钢的低温强度和塑性
▲ 作者：FENG WANG, MIAO SONG, MOHAMED N. ELKOT, NING YAO, BINHAN SUN, MIN SONG, ET AL.
▲ 链接：
https://www.science.org/doi/10.1126/science.ado2919
▲ 摘要：
沉淀物对制造机械强度高的金属材料相当主要。在这项工作中，研究组报导了B2相（有序体心立方）纳米沉淀（凡是被认为是不成剪切的金属间化合物）在低温拉伸载荷进程中在轻质复合钢中的位错切割。
因为亚纳米标准局部化学有序区的显著强化和基体中多主元素较着的固溶强化，奥氏体基体中位错滑移的高强度程度实现了剪切。这类机制不但操纵了本来难以穿透的脆性纳米沉淀物所供给的强烈强化和应变硬化，并且还经由过程其持续剪切和延续变形引入了塑性。
是以，这类钢材展现了超高的低温拉伸强度，高达2吉帕，拉伸伸长率到达34%。这项研究揭露了一种设计高机能布局材料的新策略。
▲ 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.
地球科学Earth Science
Heinrich event ice discharge and the fate of the Atlantic Meridional Overturning Circulation
海因里希事务冰排放与年夜西洋经向翻转环流的命运
▲ 作者：YUXIN ZHOU AND JERRY F. MCMANUS
▲ 链接：
https://www.science.org/doi/10.1126/science.adh8369
▲ 摘要：
在海因里希事务时代，庞大的冰山“舰队”偶然沉没北年夜西洋，减弱了翻转环流。这些事务的冰排放限制了翻转环流对冰山熔化的敏感性。
研究组重建了海因里希事务4时代的这些冰排放，发现其高达0.13 Sv（1 Sv = 100万立方米每秒），而在所有事务中平均值仅为0.029 Sv。现在格陵兰冰盖的冰山崩解与中等范围海因里希事务相当。
跟着将来格陵兰冰盖从海洋终点出口减退，仅冰山崩解尚不足以对年夜西洋翻转环流造成灾害性粉碎，其可能不会延续足够长的时候，虽然加快的格陵兰径流和延续的全球变暖依然要挟着环流的不变性。
▲ 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.
社会学Sociology
Supersharers of fake news on Twitter
推特上的假新闻超等分享者
▲ 作者：SAHAR BARIBI-BARTOV, BRIONY SWIRE-THOMPSON AND NIR GRINBERG
▲ 链接：
https://www.science.org/doi/10.1126/science.adl4435
▲ 摘要：
当局也许有能力让假新闻充溢社交媒体，但通俗选平易近若何利用这些泛滥的假新闻却不为人知。
在这项工作中，研究组肯定了2107名挂号的美国选平易近，2020年美国总统年夜选时代，他们在由664391名选平易近构成的全部群组中在Twitter上分享了80%的假新闻。成果发现超等分享者是该收集的主要成员，在该平台注册选平易近中占比高达5.2%。
超等分享者中女性、老年人和注册共和党人的比例较着太高。超等分享者的庞大流量仿佛并不是主动发生，而是经由过程人工和延续转发发生的。这些发现凸显了社交媒体对平易近主的懦弱性，在社交媒体上，一小群人曲解了很多人的政治实际。
▲ 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.
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