編譯|未玖
Science, 2 AUG 2024, VOL 385, ISSUE 6708 《科學》2024年8月2日，第385卷，6708期
材料科學Materials Science
Event-responsive scanning transmission electron microscopy
事件響應型掃描透射電子顯微鏡
▲ 作者：JONATHAN J. P. PETERS, BRYAN W. REED, YU JIMBO, KANAKO NOGUCHI, KARIN H. MüLLER, ALEXANDRA PORTER, ET AL.
▲鏈接：
https://www.science.org/doi/10.1126/science.ado8579
▲摘要：
透射電子顯微鏡一個長期存在的限制是高能電子與任何樣品相互作用所造成的損傷。
通過重新考慮成像的基本原理，研究組展示了一種電子顯微鏡的事件響應策略，可為給定光束流提供有關樣品的更多信息。通過測量達到電子計數閾值的時間，而非等待預定義的常數時間，可提高每個電子獲得的信息。
顯微鏡通過遮蔽光束來響應這些事件，從而減少所需的總劑量。該方法自動分配劑量，以在每個像素中實現給定的信噪比，消除了與信息收益遞減相關的過量劑量。通過成像生物組織和沸石，研究組證明了該策略對光束敏感材料的廣泛適用性。
▲ Abstract：
An ever-present limitation of transmission electron microscopy is the damage caused by high-energy electrons interacting with any sample. By reconsidering the fundamentals of imaging, we demonstrate an event-responsive approach to electron microscopy that delivers more information about the sample for a given beam current. Measuring the time to achieve an electron count threshold rather than waiting a predefined constant time improves the information obtained per electron. The microscope was made to respond to these events by blanking the beam, thus reducing the overall dose required. This approach automatically apportions dose to achieve a given signal-to-noise ratio in each pixel, eliminating excess dose that is associated with diminishing returns of information. We demonstrate the wide applicability of our approach to beam-sensitive materials by imaging biological tissue and zeolite.
Nuclei engineering for even halide distribution in stable perovskite/silicon tandem solar cells
晶核工程助力穩定鈣鈦礦/硅串聯太陽能電池中鹵化物均勻分布
▲ 作者：YIHUA CHEN, NING YANG, GUANHAOJIE ZHENG, FENGTAO PEI, WENTAO ZHOU, YU ZHANG, ET AL.
▲鏈接：
https://www.science.org/doi/10.1126/science.ado9104
▲摘要：
串聯結構的寬帶隙（WBG）吸收劑結晶度差、織構弱，在實際運行中導致了嚴重的混合鹵化物—陽離子遷移和相分離。
研究組通過在任何富溴聚集體和2H相形成之前使3C相成核，來控制對成分不敏感的WBG膜生長。所得WBG吸收劑具有改善的結晶度和較強的織構，抑制了非輻射復合，增強了對各種老化應力的抵抗力。
鈣鈦礦/硅串聯太陽能電池的功率轉換效率在25 cm2有效面積內為29.4%（第三方評估為28.8%），在1 cm2有效面積內為32.5%。這些太陽能電池在封裝后，在25℃最大功率點（AM 1.5G照明，全光譜，1太陽）下運行1301小時后，保持了98.3%的初始效率；而在50℃最大功率點下運行800小時后，亦保持了90%的初始效率。
▲ Abstract：
Wide-bandgap (WBG) absorbers in tandem configurations suffer from poor crystallinity and weak texture, which leads to severe mixed halide-cation ion migration and phase segregation during practical operation. We control WBG film growth insensitive to compositions by nucleating the 3C phase before any formation of bromine-rich aggregates and 2H phases. The resultant WBG absorbers show improved crystallinity and strong texture with suppressed nonradiative recombination and enhanced resistance to various aging stresses. Perovskite/silicon tandem solar cells achieve power conversion efficiencies of 29.4% (28.8% assessed by a third party) in a 25–square centimeter active area and 32.5% in a 1–square centimeter active area. These solar cells retained 98.3 and 90% of the original efficiency after 1301 and 800 hours of operation at 25° and 50°C, respectively, at the maximum power point (AM 1.5G illumination, full spectrum, 1-sun) when encapsulated.
Additive manufacturing of highly entangled polymer networks
高度纏結聚合物網絡的增材制造
▲ 作者：ABHISHEK P. DHAND, MATTHEW D. DAVIDSON, HANNAH M. ZLOTNICK, THOMAS J. KOLIBABA, JASON P. KILLGORE AND JASON A. BURDICK
▲鏈接：
https://www.science.org/doi/10.1126/science.adn6925
▲摘要：
在單個網絡中摻入聚合物鏈纏結可協同提高剛度和韌性，但通過諸如數字光處理（DLP）的光聚合固化增材制造來實現如此密集的纏結仍難以實現。
研究組報道了一種結合了光聚合和暗聚合的簡單策略，使組成聚合物鏈在印刷結構中形成時能夠緊密纏繞。
這種可推廣的方法在室溫下實現了高單體轉化率，而不需要額外刺激（如打印后的光或熱），并且可實現高度纏結的水凝膠和彈性體的增材制造，其延伸能量比傳統DLP高出4到7倍。研究組使用這種方法打印了具有空間編程粘附濕組織特征的高分辨率和多材料結構。
▲ Abstract：
Incorporation of polymer chain entanglements within a single network can synergistically improve stiffness and toughness, yet attaining such dense entanglements through vat photopolymerization additive manufacturing [e.g., digital light processing (DLP)] remains elusive. We report a facile strategy that combines light and dark polymerization to allow constituent polymer chains to densely entangle as they form within printed structures. This generalizable approach reaches high monomer conversion at room temperature without the need for additional stimuli, such as light or heat after printing, and enables additive manufacturing of highly entangled hydrogels and elastomers that exhibit fourfold- to sevenfold-higher extension energies in comparison to that of traditional DLP. We used this method to print high-resolution and multimaterial structures with features such as spatially programmed adhesion to wet tissues.
化學Chemistry
A molecular anion pump
分子陰離子泵
▲ 作者：BAIHAO SHAO, HEYIFEI FU AND IVAN APRAHAMIAN
▲鏈接：
https://www.science.org/doi/10.1126/science.adp3506
▲摘要：
通過基于蛋白質的轉運體逆濃度梯度泵送離子是許多生物過程的基石。使用人工受體來模擬該功能仍是一項艱巨挑戰，這主要因為在高結合親和力的要求與精確按需離子捕獲和釋放特性之間難以權衡。
研究組報道了一種基于三聚腙光開關的受體，通過在二氯甲烷液膜中逆濃度梯度主動輸送氯陰離子，將光能轉化為功，起到了分子泵的作用。該系統具有易于合成、雙穩定性、優異的光開關性能和優異的ON-OFF結合性能（差異可達6個數量級）。
▲ Abstract：
Pumping ions against a concentration gradient through protein-based transporters is a cornerstone of numerous biological processes. Mimicking this function by using artificial receptors remains a daunting challenge, mainly because of the difficulties in balancing between the requirement for high binding affinities and precise and on-demand ion capture and release properties. We report a trimeric hydrazone photoswitch-based receptor that converts light energy into work by actively transporting chloride anion against a gradient through a dichloromethane liquid membrane, functioning as a molecular pump. The system manifests ease of synthesis, bistability, excellent photoswitching properties, and superb ON-OFF binding properties (difference of up to six orders of magnitude).
地球科學Earth Science
Recent tropical Andean glacier retreat is unprecedented in the Holocene
近期熱帶安第斯冰川的退縮在全新世是前所未有的
▲ 作者：ANDREW L. GORIN, JEREMY D. SHAKUN, ANDREW G. JONES, TORI M. KENNEDY, SHAUN A. MARCOTT, BRENT M. GOEHRING, ET AL.
▲鏈接：
https://www.science.org/doi/10.1126/science.adg7546
▲摘要：
近幾十年來，熱帶冰川已經退縮，但這種退縮幅度是否超過了全新世波動的范圍尚不明確。
研究組測量了橫跨熱帶安第斯山脈的四處冰川邊緣最近暴露的基巖中鈹—10和碳—14的濃度，以重建其相對于今天的過去范圍。所有樣本的核素濃度都幾乎為零，表明這些位置在全新世期間從未暴露過。
該數據表明，現在熱帶地區的許多冰川可能比至少11700年前以來的冰川要小，這使得熱帶地區成為第一個記錄該里程碑的大地區。
▲ Abstract：
Tropical glaciers have retreated over recent decades, but whether the magnitude of this retreat exceeds the bounds of Holocene fluctuations is unclear. We measured cosmogenic beryllium-10 and carbon-14 concentrations in recently exposed bedrock at the margin of four glaciers spanning the tropical Andes to reconstruct their past extents relative to today. Nuclide concentrations are near zero in almost all samples, suggesting that these locations were never exposed during the Holocene. Our data imply that many glaciers in the tropics are probably now smaller than they have been in at least 11,700 years, making the tropics the first large region where this milestone has been documented.
Mid-Pleistocene climate transition triggered by Antarctic Ice Sheet growth
南極冰蓋生長引發中更新世氣候轉型
▲ 作者：ZHISHENG AN, WEIJIAN ZHOU, ZEKE ZHANG, XU ZHANG, ZHONGHUI LIU, YOUBIN SUN, ET AL.
▲鏈接：
https://www.science.org/doi/10.1126/science.abn4861
▲摘要：
盡管人們進行了廣泛的研究，但中更新世氣候轉型的性質和原因仍然是個謎。
在這項工作中，研究組通過綜合與半球冰蓋演化相關的更新世中高緯度代用記錄，來評估其與兩極冰蓋異步發展的聯系。該研究結果表明，南極冰蓋（AISs）在200萬至125萬年前大幅增長，早于北半球冰蓋在約125萬年前之后的快速擴張。
代理模型比較表明，AIS和相關的南大洋海冰擴張可導致北部高緯度地區變冷，并增強向北半球的水汽輸送，從而引發中更新世氣候轉型。所涉及的動態過程對于評估已引發異步兩極冰蓋融化的現代全球變暖至關重要。
▲ Abstract：
Despite extensive investigation, the nature and causes of the Mid-Pleistocene Transition remain enigmatic. In this work, we assess its linkage to asynchronous development of bipolar ice sheets by synthesizing Pleistocene mid- to high-latitude proxy records linked to hemispheric ice sheet evolution. Our results indicate substantial growth of the Antarctic Ice Sheets (AISs) at 2.0 to 1.25 million years ago, preceding the rapid expansion of Northern Hemisphere Ice Sheets after ~1.25 million years ago. Proxy-model comparisons suggest that AIS and associated Southern Ocean sea ice expansion can induce northern high-latitude cooling and enhanced moisture transport to the Northern Hemisphere, thus triggering the Mid-Pleistocene Transition. The dynamic processes involved are crucial for assessing modern global warming that is already inducing asynchronous bipolar melting of ice sheets.