物理学

Physics

▲ 作者：Luca Di Mascolo, Alexandro Saro, Tony Mroczkowski, Stefano Borgani, Eugene Churazov, Elena Rasia, Paolo Tozzi, Helmut Dannerbauer, Kaustuv Basu, Christopher L. Carilli, Michele Ginolfi, George Miley, Mario Nonino, Maurilio Pannella, Laura Pentericci & Francesca Rizzo

▲ 链接：

https://www.nature.com/articles/s41586-023-05761-x

▲ 摘要：

星系团是宇宙中质量最大的引力束缚结构，由数千个星系组成，弥漫的热星系团内介质（ICM），主导着这些系统的重子内容。研究者报道了在原星团方向上热苏尼亚耶夫-泽尔多维奇效应（SZ）效应的探测（约6σ）。

事实上，SZ信号以一种对宇宙变暗不敏感的方式揭示了ICM的热能，使其成为追踪宇宙结构热历史的理想选择。研究表明，大约100亿年前，在红移z= 2.156的蜘蛛网原星团中存在一个新生的ICM。

探测到的信号的振幅和形态表明，来自原星系团的SZ效应低于从动力学角度考虑的预期，与低红移群尺度系统的SZ效应相当，这与对本地星系团动态活跃的前体的预期一致。

▲ Abstract：

Galaxy clusters are the most massive gravitationally bound structures in the Universe, comprising thousands of galaxies and pervaded by a diffuse, hot intracluster medium (ICM) that dominates the baryonic content of these systems. Here we report the detection (about 6σ) of the thermal Sunyaev–Zeldovich (SZ) effect in the direction of a protocluster. In fact, the SZ signal reveals the ICM thermal energy in a way that is insensitive to cosmological dimming, making it ideal for tracing the thermal history of cosmic structures. This result indicates the presence of a nascent ICM within the Spiderweb protocluster at redshift z=2.156, around 10 billion years ago. The amplitude and morphology of the detected signal show that the SZ effect from the protocluster is lower than expected from dynamical considerations and comparable with that of lower-redshift group-scale systems, consistent with expectations for a dynamically active progenitor of a local galaxy cluster.

▲ 作者：B. Duran, Z.-E. Meziani, S. Joosten, M. K. Jones, S. Prasad, C. Peng, W. Armstrong, H. Atac, E. Chudakov, H. Bhatt, D. Bhetuwal, M. Boer, A. Camsonne, J.-P. Chen, M. M. Dalton, N. Deokar, M. Diefenthaler, J. Dunne, L. El Fassi, E. Fuchey, H. Gao, D. Gaskell, O. Hansen, F. Hauenstein, …Z. Zhao

▲ 链接：

https://www.nature.com/articles/s41586-023-05730-4

▲ 摘要：

质子是宇宙中所有可见物质的主要组成部分之一。它的固有性质包括电荷、质量和自旋。人们对质子的内部质量密度知之甚少，它主要由胶子所携带的能量所控制。由于胶子不携带电磁电荷，因此很难通过电子散射获得。

研究者使用一个小的彩色偶极子，通过J/ψ粒子的阈值光产生来研究胶子的重力密度。他们从测量中确定了质子的胶子引力形式因子，使用各种模型确定了一个明显小于电荷半径的质量半径。

在一些情况下，确定的半径可以很好地符合晶格量子色动力学的第一原理预测。研究为更深入地理解胶子在为可见物质提供引力质量方面的显著作用铺平了道路。

▲ Abstract：

The proton is one of the main building blocks of all visible matter in the Universe. Among its intrinsic properties are its electric charge, mass and spin. By contrast, little is known about the inner mass density of the proton, which is dominated by the energy carried by gluons. Gluons are hard to access using electron scattering because they do not carry an electromagnetic charge. Here we investigated the gravitational density of gluons using a small colour dipole, through the threshold photoproduction of the J/ψ particle. We determined the gluonic gravitational form factors of the proton from our measurement. We used a variety of models and determined, in all cases, a mass radius that is notably smaller than the electric charge radius. In some, but not all cases, depending on the model, the determined radius agrees well with first-principle predictions from lattice quantum chromodynamics. This work paves the way for a deeper understanding of the salient role of gluons in providing gravitational mass to visible matter.

化学物理

Chemical Physics

▲ 作者：Tomi K. Baikie, Laura T. Wey, Joshua M. Lawrence, Hitesh Medipally, Erwin Reisner, Marc M. Nowaczyk, Richard H. Friend, Christopher J. Howe, Christoph Schnedermann, Akshay Rao & Jenny Z. Zhang

▲ 链接：

https://www.nature.com/articles/s41586-023-05763-9

▲ 摘要：

光系统II和I（PSII, PSI）是驱动光合作用光反应的反应中心复合物；PSII执行光驱动水氧化和PSI进一步光能量收集电子。

作者演示了使用体内超快瞬态吸收（TA）光谱，在早期点（光激发后几皮秒）直接从活蓝藻细胞或孤立的光系统光激发PSI和PSII中提取电子，以及外源电子介质，如2,6-二氯-1,4-苯醌（DCBQ）和甲基紫ologen。

他们假设这些介质在初始光激发后氧化外周叶绿素色素，参与高度离域的电荷转移状态。该研究结果挑战了先前的模型，即光激发反应中心与光系统蛋白质支架绝缘，为生物技术和半人工光合作用的研究和重新布线开辟了新的途径。

▲ Abstract：

Photosystems II and I (PSII, PSI) are the reaction centre-containing complexes driving the light reactions of photosynthesis; PSII performs light-driven water oxidation and PSI further photo-energizes harvested electrons. The impressive efficiencies of the photosystems have motivated extensive biological, artificial and biohybrid approaches to ‘re-wire’ photosynthesis for higher biomass-conversion efficiencies and new reaction pathways, such as H₂ evolution or CO₂ fixation. Previous approaches focused on charge extraction at terminal electron acceptors of the photosystems. Electron extraction at earlier steps, perhaps immediately from photoexcited reaction centres, would enable greater thermodynamic gains; however, this was believed impossible with reaction centres buried at least 4nm within the photosystems. Here, we demonstrate, using in vivo ultrafast transient absorption (TA) spectroscopy, extraction of electrons directly from photoexcited PSI and PSII at early points (several picoseconds post-photo-excitation) with live cyanobacterial cells or isolated photosystems, and exogenous electron mediators such as 2,6-dichloro-1,4-benzoquinone (DCBQ) and methyl viologen. We postulate that these mediators oxidize peripheral chlorophyll pigments participating in highly delocalized charge-transfer states after initial photo-excitation. Our results challenge previous models that the photoexcited reaction centres are insulated within the photosystem protein scaffold, opening new avenues to study and re-wire photosynthesis for biotechnologies and semi-artificial photosynthesis.

▲ 作者：Yuqi Sun, Lishuang Ge, Linjie Dai, Changsoon Cho, Jordi Ferrer Orri, Kangyu Ji, Szymon J. Zelewski, Yun Liu, Alessandro J. Mirabelli, Youcheng Zhang, Jun-Yu Huang, Yusong Wang, Ke Gong, May Ching Lai, Lu Zhang, Dan Yang, Jiudong Lin, Elizabeth M. Tennyson, Caterina Ducati, Samuel D. Stranks, Lin-Song Cui & Neil C. Greenham

▲ 链接：

https://www.nature.com/articles/s41586-023-05792-4

▲ 摘要：

钙钛矿发光二极管（LED）由于其快速提高的外量子效率（EQEs）引起广泛关注。然而，大多数钙钛矿LED的高EQEs是在低电流密度（<1 mA cm⁻²）和低亮度下报告的。效率降低和在高亮度下的快速降解抑制了它们的实际应用。研究者展示了在高亮度下具有优异性能的钙钛矿LED，通过引入一种多功能分子来实现，该分子同时去除钙钛矿薄膜中的非辐射区域，并抑制钙钛矿与电荷传输层界面处的发光猝灭。由此产生的LED发射800 纳米的近红外光，在33 mA cm⁻²时显示23.8%的峰值EQE，在高达1,000 mA cm⁻²的高电流密度下保持10%以上的EQE。在高亮度下高效稳定的钙钛矿LED的演示是迈向商业化的重要一步，并开辟了超越传统LED技术（如钙钛矿电泵浦激光器）的新机会。

▲ Abstract：

Perovskite light-emitting diodes (LEDs) have attracted broad attention due to their rapidly increasing external quantum efficiencies (EQEs). However, most high EQEs of perovskite LEDs are reported at low current densities (<1 mA cm⁻²) and low brightness. Decrease in efficiency and rapid degradation at high brightness inhibit their practical applications. Here, we demonstrate perovskite LEDs with exceptional performance at high brightness, achieved by the introduction of a multifunctional molecule that simultaneously removes non-radiative regions in the perovskite films and suppresses luminescence quenching of perovskites at the interface with charge-transport layers. The resulting LEDs emit near-infrared light at 800 nm, show a peak EQE of 23.8% at 33 mA cm⁻² and retain EQEs more than 10% at high current densities of up to 1,000 mA cm⁻².The demonstration of efficient and stable perovskite LEDs at high brightness is an important step towards commercialization and opens up new opportunities beyond conventional LED technologies, such as perovskite electrically pumped lasers.　　

生态学和气候学

Ecology & climatology

▲ 作者：Marcos Fernández-Martínez, Josep Peñuelas, Frederic Chevallier, Philippe Ciais, Michael Obersteiner, Christian Rödenbeck, Jordi Sardans, Sara Vicca, Hui Yang, Stephen Sitch, Pierre Friedlingstein, Vivek K. Arora, Daniel S. Goll, Atul K. Jain, Danica L. Lombardozzi, Patrick C. McGuire & Ivan A. Janssens

▲ 链接：

https://www.nature.com/articles/s41586-023-05725-1

▲ 摘要：

近几十年来，全球净陆地碳吸收量或净生物群落产量（NBP）有所增加。然而，其时间变异性和自相关性在这一时期是否发生了变化，仍难以捉摸，尽管两者的增加可能表明不稳定碳汇的潜力增加。

研究者利用两个大气反演模型、分布在太平洋上的9个监测站的大气CO₂ 浓度的季节周期振幅和全球动态植被模型，研究了1981~2018年陆地净碳吸收的趋势和控制因素及其时间变异和自相关性。

结果表明，年NBP及其年代际变化在全球范围内呈上升趋势，而时间自相关性呈下降趋势。研究结果表明，NBP在区域上的变异性不断增加，这主要归因于气候变化，这可能表明碳-气候耦合系统的不稳定。

▲ Abstract：

Global net land carbon uptake or net biome production (NBP) has increased during recent decades1. Whether its temporal variability and autocorrelation have changed during this period, however, remains elusive, even though an increase in both could indicate an increased potential for a destabilized carbon sink. Here, we investigate the trends and controls of net terrestrial carbon uptake and its temporal variability and autocorrelation from 1981 to 2018 using two atmospheric-inversion models, the amplitude of the seasonal cycle of atmospheric CO₂  concentration derived from nine monitoring stations distributed across the Pacific Ocean and dynamic global vegetation models. We find that annual NBP and its interdecadal variability increased globally whereas temporal autocorrelation decreased. Our results show increasing variability of NBP regionally that can be mostly attributed to climate change and that may point to destabilization of the coupled carbon–climate system.

▲ 作者：Qian Li, Matthew H. England, Andrew McC. Hogg, Stephen R. Rintoul & Adele K. Morrison

▲ 链接：

https://www.nature.com/articles/s41586-023-05762-w

▲ 摘要：

深海环流是全球经向翻转环流的重要组成部分，在全球海洋中循环热量、碳、氧和营养物质。研究者使用一个瞬态强制高分辨率海洋-海冰耦合模型来表明，在高排放情景下，深海变暖将在未来30年加速。

他们发现，南极周围的融水输入推动了南极底水（AABW）的收缩，开辟了一条通路，使温暖的环极深水更容易进入大陆架。AABW形成的减少导致深海变暖和老化，这与最近的测量结果一致。

相比之下，风和热强迫对AABW的性质、年龄和体积影响不大。这些结果强调了南极融水在造成深海翻覆方面的关键重要性，对全球海洋生物地球化学和气候的影响可能会持续几个世纪。

▲ Abstract：

The abyssal ocean circulation is a key component of the global meridional overturning circulation, cycling heat, carbon, oxygen and nutrients throughout the world ocean. The strongest historical trend observed in the abyssal ocean is warming at high southern latitudes, yet it is unclear what processes have driven this warming, and whether this warming is linked to a slowdown in the ocean’s overturning circulation. Furthermore, attributing change to specific drivers is difficult owing to limited measurements, and because coupled climate models exhibit biases in the region. In addition, future change remains uncertain, with the latest coordinated climate model projections not accounting for dynamic ice-sheet melt. Here we use a transient forced high-resolution coupled ocean–sea-ice model to show that under a high-emissions scenario, abyssal warming is set to accelerate over the next 30 years. We find that meltwater input around Antarctica drives a contraction of Antarctic Bottom Water (AABW), opening a pathway that allows warm Circumpolar Deep Water greater access to the continental shelf. The reduction in AABW formation results in warming and ageing of the abyssal ocean, consistent with recent measurements. In contrast, projected wind and thermal forcing has little impact on the properties, age and volume of AABW. These results highlight the critical importance of Antarctic meltwater in setting the abyssal ocean overturning, with implications for global ocean biogeochemistry and climate that could last for centuries.