編譯｜馮維維
Science, 28 FEB 2025,VOLUME 387, ISSUE 6737
《科學》2025年2月28日，第387卷，6737期
物理Physics
Visualizing nanoparticle surface dynamics and instabilities enabled by deep denoising
通過深度去噪實現納米顆粒表面動態和不穩定性的可視化
▲ 作者：PETER A. CROZIER, MATAN LEIBOVICH, PIYUSH HALUAI, MAI TAN, ANDREW M. THOMAS, JOSHUA VINCENT, SREYAS MOHAN, ADRIA MARCOS MORALES, SHREYAS A. KULKARNI, AND CARLOS FERNANDEZ-GRANDA
▲鏈接：
https://www.science.org/doi/10.1126/science.ads2688
▲摘要：
材料的功能可能與發生在毫秒時間尺度上的原子級結構動力學有關。然而，電子顯微鏡成像結構具有高空間分辨率和毫秒級時間分辨率的能力往往受到較差的信噪比的限制。通過無監督深度去噪框架，研究者在中等電子劑量下觀察到氣體環境中金屬納米顆粒表面（氧化鈰上的鉑納米顆粒）的時間分辨率低至10毫秒。
在這個時間尺度上，許多納米顆粒表面連續地在有序和無序構型之間轉換。應力場可以穿透表面以下，導致缺陷的形成和不穩定，從而使納米顆粒具有流動性。將這種無監督去噪與原位電子顯微鏡相結合，極大地改善了時空表征，為探索材料的原子級結構動力學打開了新的窗口。
▲Abstract：
Materials functionalities may be associated with atomic-level structural dynamics occurring on the millisecond timescale. However, the capability of electron microscopy to image structures with high spatial resolution and millisecond temporal resolution is often limited by poor signal-to-noise ratios. With an unsupervised deep denoising framework, we observed metal nanoparticle surfaces (platinum nanoparticles on cerium oxide) in a gas environment with time resolutions down to 10 milliseconds at a moderate electron dose. On this timescale, many nanoparticle surfaces continuously transition between ordered and disordered configurations. Stress fields can penetrate below the surface, leading to defect formation and destabilization, thus making the nanoparticle fluxional. Combining this unsupervised denoiser with in situ electron microscopy greatly improves spatiotemporal characterization, opening a new window for the exploration of atomic-level structural dynamics in materials.
Curvature-guided depletion stabilizes Kagome superlattices of nanocrystals
曲率引導耗盡穩定納米晶體的籠目超晶格
▲ 作者：SIYU WAN, XIUYANG XIA, YUTONG GAO, HEYANG ZHANG, ZHEBIN ZHANG, FANGYUE WU, XUESONG WU, DONG YANG, TONGTAO LI, AND ANGANG DONG
▲鏈接：
https://www.science.org/doi/10.1126/science.adu4125
▲摘要：
調節“啞鈴”形納米晶體的曲率可以控制粒子鍵合的方向性，從而形成各種復雜的二維超晶格。
研究者發現，這些稀土氟化物膠體的超晶格形成是由曲率引導的耗盡相互作用驅動的全局互鎖自組裝造成的，這是傳統凸粒子難以實現的。該方法還可以穩定具有周期性空位的結構，如手性籠目晶格。
▲ Abstract：
Adjusting the curvature of dumbbell-shaped nanocrystals can control particle bonding directionality to form a variety of intricate two-dimensional superlattices. Wan et al. found that superlattice formation from these rare earth fluoride colloids results from globally interlocking self-assembly driven by curvature-guided depletion interactions that are difficult to achieve with conventional convex particles. This method could also stabilize structures with periodic vacancies, such as the chiral Kagome lattice.
化學Chemistry
Berkelium–carbon bonding in a tetravalent berkelocene
四價黑綠統中的鈹碳鍵合
▲ 作者：DOMINIC R. RUSSO, ALYSSA N. GAISER, AMY N. PRICE, DUMITRU-CLAUDIU SERGENTU, JENNIFER N. WACKER, NICHOLAS KATZER, APPIE A. PETERSON, JACOB A. BRANSON, XIAOJUAN YU, AND STEFAN G. MINASIAN
▲鏈接：
https://www.science.org/doi/10.1126/science.adr3346
▲摘要：
自從在曼哈頓計劃期間首次研究錒系有機金屬在同位素分離中的應用以來，人們對錒系-碳鍵的興趣一直存在。跨钚有機金屬很少被分離和結構表征，可能是由于同位素庫存有限，缺乏適當的實驗室基礎設施，以及所需厭氧條件的內在困難。
二茂鐵是夾在兩個碳環之間的鐵離子，其結構的闡明是有機金屬化學理論和實踐的基礎。在隨后的幾十年里，許多類似的金屬夾層化合物被制備和應用。研究者將基序擴展到比鈾重的放射性元素锫。
他們的實驗需要在亞毫克的尺度上快速合成和表征，以補償正在進行的衰變。光譜和理論分析支持了金屬環配體和f軌道之間的共價相互作用。
▲ Abstract：
Interest in actinide–carbon bonds has persisted since actinide organometallics were first investigated for applications in isotope separation during the Manhattan Project. Transplutonium organometallics are rarely isolated and structurally characterized, likely owing to limited isotope inventories, a scarcity of suitable laboratory infrastructure, and intrinsic difficulties with the anaerobic conditions required. Elucidating the structure of ferrocene, an iron ion sandwiched between two carbon rings, was foundational to the theory and practice of organometallic chemistry. In the ensuing decades, numerous analogous metal sandwich compounds have been prepared and applied. Russo et al. now extend the motif to berkelium, a radioactive element heavier than uranium. Their experiments required rapid synthesis and characterization on a submilligram scale to compensate for the ongoing decay. Spectroscopic and theoretical analysis supported covalent interactions between the cyclic ligands and f orbitals of the metal.
Nitrogen dominates global atmospheric organic aerosol absorption
氮在全球大氣有機氣溶膠吸收中占主導地位
▲ 作者：YUMIN LI, TZUNG-MAY FU, JIAN ZHEN YU, AOXING ZHANG, XU YU, JIANHUAI YE, LEI ZHU, HUIZHONG SHEN, CHEN WANG, AND COLETTE L. HEALD
▲鏈接：
https://www.science.org/doi/10.1126/science.adr4473
▲摘要：
大氣氣溶膠通過散射或吸收太陽輻射來影響氣候。然而，它們的進化組成和吸收作用之間的聯系尚不清楚。研究者發現棕色氮，即有機氣溶膠的含氮成分，在全球范圍內主導著大氣有機氣溶膠的太陽能吸收。
他們使用一個模型來量化大氣中棕色氮的分布，計算化學老化如何影響其光學特性，并量化其輻射影響。這些結果將有助于改進有機氣溶膠對氣候影響的歸因。
▲ Abstract：
Atmospheric aerosols affect climate by either scattering or absorbing solar radiation. Li et al. found that brown nitrogen, the nitrogenous component of organic aerosols, dominates their solar absorption globally. The authors used a model to quantify the atmospheric distribution of brown nitrogen, calculated how chemical aging affects its optical properties, and quantified its radiative impacts. These results will help to improve attribution of the climate effects of organic aerosols.
植物病理學Plant Pathology
A widespread plant defense compound disarms bacterial type III injectisome assembly
一種植物防御化合物讓細菌解除“武裝”
▲ 作者：PEI MIAO, HAIJUN WANG, WEI WANG, ZHENGDONG WANG, HAN KE, HANGYUAN CHENG, JINJING NI, JINGNAN LIANG, YU-FENG YAO, AND XIAOGUANG LEI
▲ 鏈接：https://www.science.org/doi/10.1126/science.ads0377
▲摘要：
III型分泌系統（T3SS）是細菌將效應蛋白注入宿主細胞的一種機制。然而，宿主介導的毒力阻斷機制，特別是代謝物阻斷機制，尚不清楚。
研究者發現了一種被稱為芥子酰胺的植物抗菌素，它由幾種植物產生，并阻斷兩種細菌的T3SS功能。芥子酰胺的靶點是保守的細菌III型分泌系統注射器蛋白HrcC。芥子酰胺積累是植物防御的一部分，研究發現芥子酰胺減少的轉基因植物易受細菌感染。
▲ Abstract：
The type III secretion system (T3SS) is used by bacterial species to inject effector proteins into host cells. However, the mechanisms of host-mediated blockage of virulence, especially by metabolites, are not well understood. Miao et al. uncovered a phytoalexin called erucamide that is produced by several plant species and blocks T3SS function in two bacterial species. The target of erucamide is the conserved bacterial type III secretion system syringe protein HrcC. Erucamide accumulation is part of plant defense, and transgenic plants with reduced erucamide were found to be susceptible to bacterial infection.
Plant pathogenic fungi hijack phosphate signaling with conserved enzymatic effectors
植物病原真菌用保守的酶效應物劫持磷酸鹽信號
▲ 作者：CARL L. MCCOMBE, ALEX WEGNER, LOUISA WIRTZ, CHENIE S. ZAMORA, FLORENCIA CASANOVA, SHOUVIK ADITYA , JULIAN R. GREENWOOD, SAMUEL DE PAULA, ELEANOR ENGLAND, AND ULRICH SCHAFFRATH
▲鏈接：
https://www.science.org/doi/10.1126/science.adl5764
▲摘要：
植物病原體通常會釋放蛋白質以靶向宿主機制，從而提高其感染成功率。研究者人分析了NUDIX蛋白家族。該家族存在于多種病原體中，并針對多種植物物種。
他們發現真菌病原體可以利用NUDIX蛋白通過破壞植物感知自身無機磷酸鹽狀態的能力來欺騙植物。NUDIX蛋白水解肌醇焦磷酸，這是植物細胞監測的主要磷酸化合物。如果植物專注于生長和營養，那么它可能不太能夠激活免疫反應。
▲ Abstract：
Plant pathogens often release proteins to target host machinery and increase their infection success. McCombe et al. examined the NUDIX family of proteins, which are found in diverse pathogens and target multiple plant species. They found that fungal pathogens can use NUDIX proteins to trick plants by disrupting their ability to sense their own inorganic phosphate status. NUDIX proteins hydrolyze inositol pyrophosphate, which is the main phosphate compound monitored by plant cells. If the plant focuses on growth and nutrition, then it may be less able to activate immune responses.
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