Science,2 AUG 2024, VOL 385, ISSUE 6708

《科学》2024年8月2日，第385卷，6708期

材料科学Materials Science

Event-responsive scanning transmission electron microscopy

事务响应型扫描透射电子显微镜

▲ 作者：JONATHAN J. P. PETERS, BRYAN W. REED, YU JIMBO, KANAKO NOGUCHI, KARIN H. MüLLER, ALEXANDRA PORTER, ET AL.

▲链接：

https://www.science.org/doi/10.1126/science.ado8579

▲摘要：

透射电子显微镜一个持久存在的限制是高能电子与任何样品彼此感化所酿成的毁伤。

经由过程从头斟酌成像的根基道理，研究组展现了一种电子显微镜的事务响应策略，可为给定光束流供给有关样品的更多信息。经由过程丈量到达电子计数阈值的时候，而非期待预界说的常数时候，可提高每一个电子取得的信息。

显微镜经由过程掩蔽光束来响应这些事务，从而削减所需的总剂量。该方式主动分派剂量，以在每一个像素中实现给定的信噪比，消弭了与信息收益递减相干的过量剂量。经由过程成像生物组织和沸石，研究组证实了该策略对光束敏感材料的普遍合用性。

▲ 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

晶核工程助力不变钙钛矿/硅串连太阳能电池中卤化物平均散布

▲ 作者：YIHUA CHEN, NING YANG, GUANHAOJIE ZHENG, FENGTAO PEI, WENTAO ZHOU, YU ZHANG, ET AL.

▲链接：

https://www.science.org/doi/10.1126/science.ado9104

▲摘要：

串连布局的宽带隙（WBG）接收剂结晶度差、织构弱，在现实运行中致使了严重的夹杂卤化物—阳离子迁徙和相分手。

研究组经由过程在任何富溴堆积体和2H相构成之前使3C相成核，来节制对成份不敏感的WBG膜发展。所得WBG接收剂具有改良的结晶度和较强的织构，按捺了非辐射复合，加强了对各类老化应力的反抗力。

钙钛矿/硅串连太阳能电池的功率转换效力在25 cm2有用面积内为29.4%（第三方评估为28.8%），在1 cm2有用面积内为32.5%。这些太阳能电池在封装后，在25℃最年夜功率点（AM 1.5G照明，全光谱，1太阳）下运行1301小时后，连结了98.3%的初始效力；而在50℃最年夜功率点下运行800小时后，亦连结了90%的初始效力。

▲ 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

高度缠结聚合物收集的增材制造

▲ 作者：ABHISHEK P. DHAND, MATTHEW D. DAVIDSON, HANNAH M. ZLOTNICK, THOMAS J. KOLIBABA, JASON P. KILLGORE AND JASON A. BURDICK

▲链接：

https://www.science.org/doi/10.1126/science.adn6925

▲摘要：

在单个收集中掺入聚合物链缠结可协同提高刚度和韧性，但经由过程诸如数字光处置（DLP）的光聚合固化增材制造来实现如斯密集的缠结仍难以实现。

研究组报导了一种连系了光聚合和暗聚合的简单策略，使构成聚合物链在印刷布局中构成时可以或许慎密环绕纠缠。

这类可推行的方式在室温下实现了高单体转化率，而不需要额外刺激（如打印后的光或热），而且可实现高度缠结的水凝胶和弹性体的增材制造，其延长能量比传统DLP超出跨越4到7倍。研究组利用这类方式打印了具有空间编程粘附湿组织特点的高分辩率和多材料布局。

▲ 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.

化学Chemistry

A molecular anion pump

份子阴离子泵

▲ 作者：BAIHAO SHAO, HEYIFEI FU AND IVAN APRAHAMIAN

▲链接：

https://www.science.org/doi/10.1126/science.adp3506

▲摘要：

经由过程基在卵白质的转运体逆浓度梯度泵送离子是很多生物进程的基石。利用人工受体来摹拟该功能还是一项艰难挑战，这首要由于在高连系亲和力的要求与切确按需离子捕捉和释放特征之间难以衡量。

研究组报导了一种基在三聚腙光开关的受体，经由过程在二氯甲烷液膜中逆浓度梯度自动输送氯阴离子，将光能转化为功，起到了份子泵的感化。该系统具有易在合成、双不变性、优良的光开关机能和优良的ON-OFF连系机能（差别可达6个数目级）。

▲ 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).

地球科学Earth Science

Recent tropical Andean glacier retreat is unprecedented in the Holocene

近期热带安第斯冰川的畏缩在全新世是史无前例的

▲ 作者：ANDREW L. GORIN, JEREMY D. SHAKUN, ANDREW G. JONES, TORI M. KENNEDY, SHAUN A. MARCOTT, BRENT M. GOEHRING, ET AL.

▲链接：

https://www.science.org/doi/10.1126/science.adg7546

▲摘要：

近几十年来，热带冰川已畏缩，但这类畏缩幅度是不是跨越了全新世波动的规模尚不明白。

研究组丈量了横跨热带安第斯山脉的四周冰川边沿比来表露的基岩中铍—10和碳—14的浓度，以重建其相对今天的曩昔规模。所有样本的核素浓度都几近为零，注解这些位置在全新世时代从未表露过。

该数据注解，此刻热带地域的很多冰川可能比最少11700年前以来的冰川要小，这使得热带地域成为第一个记实该里程碑的年夜地域。

▲ 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

南极冰盖发展激发中更新世天气转型

▲ 作者：ZHISHENG AN, WEIJIAN ZHOU, ZEKE ZHANG, XU ZHANG, ZHONGHUI LIU, YOUBIN SUN, ET AL.

▲链接：

https://www.science.org/doi/10.1126/science.abn4861

▲摘要：

虽然人们进行了普遍的研究，但中更新世天气转型的性质和缘由依然是个谜。

在这项工作中，研究组经由过程综合与半球冰盖演变相干的更新世中高纬度代用记实，来评估其与南北极冰盖异步成长的联系。该研究成果注解，南极冰盖（AISs）在200万至125万年前年夜幅增加，早在北半球冰盖在约125万年前以后的快速扩大。

代办署理模子比力注解，AIS和相干的南年夜洋海冰扩大可致使北部高纬度地域变冷，并加强向北半球的水汽输送，从而激发中更新世天气转型。所触及的动态进程对评估已激发异步南北极冰盖熔化的现代全球变暖相当主要。

▲ 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 synthesizin开云体育appg 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.