編譯 | 李言
Nature, 24 November 2022, Volume 611 Issue 7937
《自然》2022年11月24日，第611卷，7937期
物理學Physics
Polarized blazar X-rays imply particle acceleration in shocks
偏振耀變體x射線暗示粒子被激波加速
▲ 作者：Ioannis Liodakis, Alan P. Marscher, Iván Agudo et al.
▲ 連結：
https://www.nature.com/articles/s41586-022-05338-0
▲ 摘要：
射電到光學偏振的測量——迄今為止唯一可用的測量範圍——探測的是射流中含有粒子的擴展區域，這些粒子在數天至數年前離開了加速點，因此不能像x射線測量那樣直接探索加速機制。在此，我們報導了耀變體馬卡良501 (Mrk 501)的x射線偏振探測。我們測量到的X射線波段的線偏振在10%左右，這比光學波長的值高約2倍，偏振角與射電射流平行。這表明激波鋒面是粒子加速的來源，同時也意味著等離子體隨著離激波的距離而變得越來越紊流。
▲ Abstract：
Measurements of the radio to optical polarization—the only range available until now—probe extended regions of the jet containing particles that left the acceleration site days to years earlier, and hence do not directly explore the acceleration mechanism, as could X-ray measurements. Here we report the detection of X-ray polarization from the blazar Markarian 501 (Mrk 501). We measure an X-ray linear polarization degree ΠX of around 10%, which is a factor of around 2 higher than the value at optical wavelengths, with a polarization angle parallel to the radio jet. This points to a shock front as the source of particle acceleration and also implies that the plasma becomes increasingly turbulent with distance from the shock.
材料科學Materials Science
Ultra-bright, efficient and stable Perovskite light-emitting diodes
超亮、高效、穩定的鈣鈦礦發光二極體
▲ 作者：Joo Sung Kim, Jung-Min Heo, Gyeong-Su Park et al.
▲ 連結：
https://www.nature.com/articles/s41586-022-05304-w
▲ 摘要：
在此，我們報告一種由核/殼型鈣鈦礦納米晶體製成的超亮、高效且穩定PeLED，尺寸約為10 nm，使用苄膦酸（BPA）添加劑與三維多晶鈣鈦礦薄膜的簡單原位反應，而不需要單獨的合成過程。在反應過程中，大型三維晶體分裂為納米晶體，BPA包圍納米晶體，實現了強載流子限制。BPA殼通過形成共價鍵鈍化欠配位的鉛原子，從而大大降低了陷阱密度，同時保持了三維鈣鈦礦良好的電荷輸運特性。我們同時展示了高效、明亮和穩定的PeLEDs，其最大亮度約為47萬cd m−2，最大外部量子效率為28.9%（在40個器件中平均= 25.2±1.6%），最大電流效率為151 cd A−1，在1000 cd m−2下的半衰期為520 h（估計在100 cd m−2下的半衰期為> 30000 h）。
▲ Abstract：
Here, we report an ultra-bright, efficient and stable PeLED made of core/shell perovskite nanocrystals with a size of approximately 10 nm, obtained using a simple in situ reaction of benzylphosphonic acid (BPA) additive with three-dimensional (3D) polycrystalline perovskite films, without separate synthesis processes. During the reaction, large 3D crystals are split into nanocrystals and the BPA surrounds the nanocrystals, achieving strong carrier confinement. The BPA shell passivates the undercoordinated lead atoms by forming covalent bonds, and thereby greatly reduces the trap density while maintaining good charge-transport properties for the 3D perovskites. We demonstrate simultaneously efficient, bright and stable PeLEDs that have a maximum brightness of approximately 470,000 cd m−2, maximum external quantum efficiency of 28.9% (average = 25.2 ± 1.6% over 40 devices), maximum current efficiency of 151 cd A−1 and half-lifetime of 520 h at 1,000 cd m−2 (estimated half-lifetime >30,000 h at 100 cd m−2).
Open-channel metal particle superlattices
開放通道金屬粒子超晶格
▲ 作者：Yuanwei Li, Wenjie Zhou, Ibrahim Tanriover et al.
▲ 連結：
https://www.nature.com/articles/s41586-022-05291-y
▲ 摘要：
在此，本文報導一種用DNA修飾的空心膠體納米粒子（NPs）、合成孔洞為10 ~ 1000 nm的金屬開放管道式超晶格的通用方法。通過調整空心膠體納米粒子幾何結構和DNA設計，可以調整晶體孔隙幾何結構（孔隙大小和形狀）和通道拓撲結構（孔隙相互連接的方式）。空心膠體納米粒子的構建是由邊緣到邊緣的DNA-DNA相互作用驅動的，而不是面對面的DNA-DNA相互作用。我們引入了兩個新設計規則去描述這種構建過程，併合成了12個控制晶體對稱性、通道幾何和拓撲的開放管道式超晶格。
▲ Abstract：
Here, a universal approach for synthesizing metallic open-channel superlattices with pores of 10 to 1,000 nm from DNA-modified hollow colloidal nanoparticles (NPs) is reported. By tuning hollow NP geometry and DNA design, one can adjust crystal pore geometry (pore size and shape) and channel topology (the way in which pores are interconnected). The assembly of hollow NPs is driven by edge-to-edge rather than face-to-face DNA–DNA interactions. Two new design rules describing this assembly regime emerge from these studies and are then used to synthesize 12 open-channel superlattices with control over crystal symmetry, channel geometry and topology.
化學Chemistry
Pivotal role of reversible NiO6 geometric conversion in oxygen evolution
可逆NiO6幾何轉化在析氧過程中的關鍵作用
▲ 作者：Xiaopeng Wang, Shibo Xi, Pengru Huang et al.
▲ 連結：
https://www.nature.com/articles/s41586-022-05296-7
▲ 摘要：
在此，我們報導了一種電子轉移機制，涉及到可切換的金屬和氧氧化還原化學在鎳氧氫氧化物基材料，以光為觸發器。與傳統的AEM和LOM相比，本文提出的光觸發耦合析氧機制要求單元元在析氧過程中經歷八面體（NiO6）和正方形平面（NiO4）之間的可逆幾何轉換，以實現金屬和氧的交替電子態（約在費米能級）。利用這種電子轉移途徑，可以繞過AEM中的氧氧鍵合和LOM中的脫質子化這一潛在的限制步驟。因此，與以往的電催化劑相比，通過這一途徑運行的電催化劑表現出更好的活性。我們預計，新的光觸發耦合析氧機制將增加對析氧研究場景的理解。
▲ Abstract：
Here we report an electron transfer mechanism that involves a switchable metal and oxygen redox chemistry in nickel-oxyhydroxide-based materials with light as the trigger. In contrast to the traditional AEM and LOM, the proposed light-triggered coupled oxygen evolution mechanism requires the unit cell to undergo reversible geometric conversion between octahedron (NiO6) and square planar (NiO4) to achieve electronic states (around the Fermi level) with alternative metal and oxygen characters throughout the oxygen evolution process. Utilizing this electron transfer pathway can bypass the potential limiting steps, that is, oxygen–oxygen bonding in AEM and deprotonation in LOM. As a result, the electrocatalysts that operate through this route show superior activity compared with previously reported electrocatalysts. Thus, it is expected that the proposed light-triggered coupled oxygen evolution mechanism adds a layer of understanding to the oxygen evolution research scene.
地球科學Geoscience
Extensive inland thinning and speed-up of Northeast Greenland Ice Stream
格陵蘭島東北冰流加速變薄
▲ 作者：Shfaqat A. Khan, Youngmin Choi, Mathieu Morlighem et al.
▲ 連結：
https://www.nature.com/articles/s41586-022-05301-z
▲ 摘要：
在此，我們展示東北格陵蘭冰流（NEGIS）在2012年鋒面變化引發的廣泛加速和變薄已經向內陸傳播了200多公里。我們使用獨特的全球導航衛星系統（GNSS）觀測，結合從衛星數據中獲得的地表高程變化和地錶速度，選擇用於冰流數值模型的正確基礎條件，然後將其用於未來的模擬。我們的模型結果表明，到2100年，僅這一海洋區域就將導致海平面上升13.5-15.5毫米（相當於過去50年整個冰蓋的貢獻），並將在未來造成急劇變化。這項研究表明，對內陸冰速度和海拔的細微變化的測量有助於約束未來質量平衡的數值模型，高端的預測與觀測結果更吻合。
▲ Abstract：
Here we show that extensive speed-up and thinning triggered by frontal changes in 2012 have already propagated more than 200 km inland. We use unique global navigation satellite system (GNSS) observations, combined with surface elevation changes and surface speeds obtained from satellite data, to select the correct basal conditions to be used in ice flow numerical models, which we then use for future simulations. Our model results indicate that this marine-based sector alone will contribute 13.5–15.5 mm sea-level rise by 2100 (equivalent to the contribution of the entire ice sheet over the past 50 years) and will cause precipitous changes in the coming century. This study shows that measurements of subtle changes in the ice speed and elevation inland help to constrain numerical models of the future mass balance and higher-end projections show better agreement with observations.
動物學Zoology
Odour motion sensing enhances navigation of complex plumes
氣味運動傳感增強了複雜羽流的導航能力
▲ 作者：Nirag Kadakia, Mahmut Demir, Brenden T. Michaelis et al.
▲ 連結：
https://www.nature.com/articles/s41586-022-05423-4
▲ 摘要：
在這裡，我們展示了黑腹果蠅利用一種額外的方向線索——氣味的運動方向——來決定它們的導航決策，它們利用兩個觸角之間氣味信號的時間相關性來檢測氣味的運動方向。利用高解析度的虛擬實境範式向自由行走的蒼蠅傳遞時空複雜的虛構氣味，我們證明了這種氣味方向感知涉及到類似於視覺方向感知的算法。結合模擬、理論和實驗結果，我們發現氣味運動包含有價值的方向性信息，而這些信息僅從氣流中是不存在的，果蠅和虛擬個體都可以在自然羽流導航中被這些信息幫助。我們的研究結果表明，氣味方向感應可能存在於整個動物王國，可以改善嗅覺機器人在不確定環境中的導航情況。
▲ Abstract：
Here we show that Drosophila melanogaster shape their navigational decisions using an additional directional cue—the direction of motion of odours—which they detect using temporal correlations in the odour signal between their two antennae. Using a high-resolution virtual-reality paradigm to deliver spatiotemporally complex fictive odours to freely walking flies, we demonstrate that such odour-direction sensing involves algorithms analogous to those in visual-direction sensing. Combining simulations, theory and experiments, we show that odour motion contains valuable directional information that is absent from the airflow alone, and that both Drosophila and virtual agents are aided by that information in navigating naturalistic plumes. The generality of our findings suggests that odour-direction sensing may exist throughout the animal kingdom and could improve olfactory robot navigation in uncertain environments.