《科学》（20230310出版）一周论文导读
2023/3/12 20:01:03 科学网

     编译 | 未玖

     Science, 10 MAR 2023, VOL 379, ISSUE 6636

     《科学》2023年3月10日，第379卷，6636期

    

     物理学Physics

     Observation of photon-photon thermodynamic processes under negative optical temperature conditions

     负光学温度条件下光子-光子热力学过程的观测

     ▲ 作者：A. L. MARQUES MUNIZ, F. O. WU, P. S. JUNG, M. KHAJAVIKHAN, D. N. CHRISTODOULIDES, AND U. PESCHEL.

     ▲ 链接：

     https://www.science.org/doi/10.1126/science.ade6523

     ▲ 摘要：

     统计力学要求系统温度为正，前提是系统内能没有上限。然而，如果不满足这个条件，就有可能达到热力学上倾向于高阶能态的负温度。尽管在自旋和玻色-哈伯德体系以及量子流体中都有负温度的报道，但迄今为止，在该体系中热力学过程的实验观测仍难以实现。

     研究组展示了负光学温度的等熵膨胀-压缩和焦耳膨胀，由热力学微正则光子系统中的纯非线性光子-光子相互作用实现。该光子方法为探索新型全光热机提供了一个平台，并有望在光学以外的其他玻色子系统中产生影响，例如冷原子和光力学。

     ▲ Abstract：

     Statistical mechanics demands that the temperature of a system is positive provided that its internal energy has no upper bound. Yet if this condition is not met, it is possible to attain negative temperatures for which higher-order energy states are thermodynamically favored. Although negative temperatures have been reported in spin and Bose-Hubbard settings as well as in quantum fluids, the observation of thermodynamic processes in this regime has thus far remained elusive. Here, we demonstrate isentropic expansion-compression and Joule expansion for negative optical temperatures, enabled by purely nonlinear photon-photon interactions in a thermodynamic microcanonical photonic system. Our photonic approach provides a platform for exploring new all-optical thermal engines and could have ramifications in other bosonic systems beyond optics, such as cold atoms and optomechanics.

     Quantum state–resolved molecular dipolar collisions over four decades of energy

     40年间量子态分辨的分子偶极碰撞能量

     ▲ 作者：GUOQIANG TANG, MATTHIEU BESEMER, STACH KUIJPERS, GERRIT C. GROENENBOOM, AD VAN DER AVOIRD, TIJS KARMAN, ET AL.

     ▲ 链接：

     https://www.science.org/doi/10.1126/science.adf9836

     ▲ 摘要：

     冷极性分子之间的碰撞代表了一个吸引人的研究前沿，但实验证明很难探测。

     研究组报道了能量在0.1~580 cm-1之间，以全量子态分辨率测量一氧化氮(NO)和氘化氨(ND3)分子之间碰撞的非弹性截面。在低于相互作用势的~100 cm-1阱深能量时，观测到源自特殊U型转弯轨迹的反向辉光。

     在能量低于0.2cm-1时，研究组观察到朗之万捕获模型的失效，并将其解释为碰撞过程中相互极化被抑制，有效断开了分子偶极矩。基于从头算NO-ND3势能面的散射计算揭示了具有相反宇称的近简并旋转能级在低能偶极碰撞中的关键作用。

     ▲ Abstract：

     Collisions between cold polar molecules represent a fascinating research frontier but have proven hard to probe experimentally. We report measurements of inelastic cross sections for collisions between nitric oxide (NO) and deuterated ammonia (ND3) molecules at energies between 0.1 and 580 centimeter-1, with full quantum state resolution. At energies below the ~100-centimeter-1 well depth of the interaction potential, we observed backward glories originating from peculiar U-turn trajectories. At energies below 0.2 centimeter-1, we observed a breakdown of the Langevin capture model, which we interpreted in terms of a suppressed mutual polarization during the collision, effectively switching off the molecular dipole moments. Scattering calculations based on an ab initio NO-ND3 potential energy surface revealed the crucial role of near-degenerate rotational levels with opposite parity in low-energy dipolar collisions.

     材料科学Materials Science

     Topologically localized excitons in single graphene nanoribbons

     单石墨烯纳米带中的拓扑局域激子

     ▲ 作者：SONG JIANG, TOMá? NEUMAN, ALEX BOEGLIN, FABRICE SCHEURER, AND GUILLAUME SCHULL.

     ▲ 链接：

     https://www.science.org/doi/10.1126/science.abq6948

     ▲ 摘要：

     原子级精确石墨烯纳米带(GNRs)的本征光电特性在很大程度上仍有待探索，因为生长纳米带的金属衬底会产生荧光猝灭效应。

     研究组用原子尺度的空间分辨率探测了金属表面合成GNRs的激子发射。采用基于扫描隧道显微镜(STM)的方法将GNR转移到部分绝缘表面，以防止纳米带的发光猝灭。

     STM诱导的荧光光谱揭示了与GNRs拓扑端态相关的局域暗激子发射，探测到一个低频振动发射梳，并将其归因于受限在有限框内的纵向声模。该成果为研究石墨烯纳米结构中激子、振子和拓扑结构之间的相互作用提供了一个新思路。

     ▲ Abstract：

     Intrinsic optoelectronic properties of atomically precise graphene nanoribbons (GNRs) remain largely unexplored because of luminescence quenching effects that are due to the metallic substrate on which the ribbons are grown. We probed excitonic emission from GNRs synthesized on a metal surface with atomic-scale spatial resolution. A scanning tunneling microscope (STM)–based method to transfer the GNRs to a partially insulating surface was used to prevent luminescence quenching of the ribbons. STM-induced fluorescence spectra reveal emission from localized dark excitons that are associated with the topological end states of the GNRs. A low-frequency vibronic emission comb is observed and attributed to longitudinal acoustic modes that are confined to a finite box. Our study provides a path to investigate the interplay between excitons, vibrons, and topology in graphene nanostructures.

     化学Chemistry

     Enantioselective electrochemical cobalt-catalyzed aryl C-H activation reactions

     对映选择性电化学钴催化芳基C-H活化反应

     ▲ 作者：TRISTAN VON MüNCHOW, SUMAN DANA, YANG XU, BINBIN YUAN, AND LUTZ ACKERMANN.

     ▲ 链接：

     https://www.science.org/doi/10.1126/science.adg2866

     ▲ 摘要：

     对映选择性氧化还原转化通常依赖于昂贵的过渡金属作为催化剂，也依赖于化学计量的化学氧化还原剂。电催化是一种更可持续的替代方法，亮点是通过使用析氢反应(HER)来代替化学氧化剂。

     在这项工作中，研究组报道了使用钴代替贵金属催化剂进行不对称氧化的HER-偶联对映选择性芳基碳氢键(C-H)活化反应的策略。

     藉此实现了羧基酰胺的高对映选择性碳-氢和氮-氢(C-H和N-H)环化，从而获得了点手性和轴手性化合物。此外，钴介导的电催化能够通过脱氢C-H活化反应选择性不对称性来制备各种磷(P)立体异构化合物。

     ▲ Abstract：

     Enantioselective redox transformations typically rely on costly transition metals as catalysts and often stoichiometric amounts of chemical redox agents as well. Electrocatalysis represents a more sustainable alternative, in particular through the use of the hydrogen evolution reaction (HER) in place of a chemical oxidant. In this work, we describe strategies for HER-coupled enantioselective aryl carbon-hydrogen bond (C–H) activation reactions using cobalt in place of a precious metal catalyst for the asymmetric oxidation. Thus, highly enantioselective carbon-hydrogen and nitrogen-hydrogen (C–H and N–H) annulations of carboxylic amides were achieved, which gave access to point and axially chiral compounds. Furthermore, the cobalt-mediated electrocatalysis enabled the preparation of various phosphorus (P)–stereogenic compounds by selective desymmetrization through dehydrogenative C–H activation reactions.

     动物学Zoology

     Social signal learning of the waggle dance in honey bees

     蜜蜂摇摆舞的社会信号学习

     ▲ 作者：SHIHAO DONG, TAO LIN, JAMES C. NIEH, AND KEN TAN

     ▲ 链接：

     https://www.science.org/doi/10.1126/science.ade1702

     ▲ 摘要：

     蜜蜂使用一种复杂的空间参照交流形式。它们的“摇摆舞”通过将空中线索、视网膜光流和相对食物价值编码成巢内的运动和声音，向“巢友”传达了资源的方向、距离和质量。

     研究组证明了正确的摇摆舞需要社会学习。在第一次跳舞之前没有机会跟随任何舞蹈的蜜蜂会产生明显更多的无序舞蹈，摆动角度发散误差更大，编码距离也不正确。前者的缺陷随着经验的增加而改善，但距离编码终身不变。

     第一次跟随其他“舞者”跳舞的蜜蜂则未表现出任何缺陷。因此，社会学习塑造了蜜蜂的信号，就像它在人类婴儿、鸟类和多种其他脊椎动物物种中进行交流一样。

     ▲ Abstract：

     Honey bees use a complex form of spatial referential communication. Their “waggle dance” communicates the direction, distance, and quality of a resource to nestmates by encoding celestial cues, retinal optic flow, and relative food value into motion and sound within the nest. We show that correct waggle dancing requires social learning. Bees without the opportunity to follow any dances before they first danced produced significantly more disordered dances with larger waggle angle divergence errors and encoded distance incorrectly. The former deficit improved with experience, but distance encoding was set for life. The first dances of bees that could follow other dancers showed neither impairment. Social learning, therefore, shapes honey bee signaling, as it does communication in human infants, birds, and multiple other vertebrate species.

     生态学Ecology

     Dwarfism and gigantism drive human-mediated extinctions on islands

     岛屿上的矮小物种和巨型物种更容易遭受人类介导的灭绝

     ▲ 作者：ROBERTO ROZZI, MARK V. LOMOLINO, ALEXANDRA A. E. VAN DER GEER, DANIELE SILVESTRO, S. KATHLEEN LYONS, PERE BOVER, ET AL.

     ▲ 链接：

     https://www.science.org/doi/10.1126/science.add8606

     ▲ 摘要：

     长期以来，岛屿一直被认为是独特的进化舞台，导致形态各异的物种，如矮小物种和巨型物种。

     研究组通过整合过去2300万年世界各地岛屿和古岛屿上1231种现存物种和350种灭绝物种的数据，评估了岛屿哺乳动物的体型进化如何加剧了它们的脆弱性，以及人类的到来如何促进它们过去和正在发生的灭绝。

     结果发现，在最极端的迷你物种和巨型物种岛屿中，灭绝和濒危的可能性最高。现代人类的到来加剧了岛屿哺乳动物的灭绝风险，使灭绝速度加快了10倍以上，导致这些岛屿进化的标志性演化奇迹几乎完全消亡。

     ▲ Abstract：

     Islands have long been recognized as distinctive evolutionary arenas leading to morphologically divergent species, such as dwarfs and giants. We assessed how body size evolution in island mammals may have exacerbated their vulnerability, as well as how human arrival has contributed to their past and ongoing extinctions, by integrating data on 1231 extant and 350 extinct species from islands and paleo islands worldwide spanning the past 23 million years. We found that the likelihood of extinction and of endangerment are highest in the most extreme island dwarfs and giants. Extinction risk of insular mammals was compounded by the arrival of modern humans, which accelerated extinction rates more than 10-fold, resulting in an almost complete demise of these iconic marvels of island evolution.

     编辑 | 方圆

     排版 | 郭刚

    

    

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