编译 | 李言
Nature, 3 November 2022, Volume 611 Issue 7934
《自然》2022年11月3日，第611卷，7934期
物理学
Physics
Coherent surface plasmon polariton amplification via free-electron pumping
基于自由电子受激发射的表面等离子体激元相干放大
▲ 作者：Dongdong Zhang, Yushan Zeng, Yafeng Bai, Zhongpeng Li, Ye Tian & Ruxin Li
▲ 链接：
https://www.nature.com/articles/s41586-022-05239-2
▲ 摘要：
在此，我们提出了通过自由电子受激发射的太赫兹表面等离子体激元的相干放大: 飞秒光脉冲产生具有初始太赫兹表面波的同相自由电子脉冲，它们随后的相互作用会相干地增强太赫兹表面波。
放大的基本动力学，包括辐射频率在一毫米相互作用长度上的两倍红移，通过光泵探针方法被解析为电磁场分布演变。通过将该方法扩展到适当相位匹配的电子束，我们的理论分析预测了超辐射表面波生长，这为受激
表面波光源奠定了基础，并可能促进物质操纵的手段，尤其是在太赫兹波段。
▲ Abstract：
Here we present the coherent amplification of terahertz surface plasmon polaritons via free-electron-stimulated emission: a femtosecond optical pulse creates an in-phase free-electron pulse with an initial terahertz surface wave, and their ensuing interactions intensify the terahertz surface wave coherently. The underlying dynamics of the amplification, including a twofold redshift in the radiation frequency over a one-millimetre interaction length, are resolved as electromagnetic-field-profile evolutions using an optical pump–probe method. By extending the approach to a properly phase-matched electron bunch, our theoretical analysis predicts a super-radiant surface-wave growth, which lays the ground for a stimulated surface-wave light source and may facilitate capable means for matter manipulation, especially in the terahertz band.
Strain-retardant coherent perovskite phase stabilized Ni-rich cathode
应变抑制相干钙钛矿相稳定富镍阴极
▲ 作者：Liguang Wang, Tongchao Liu, Tianpin Wu & Jun Lu
▲ 链接：
https://www.nature.com/articles/s41586-022-05238-3
▲ 摘要：
在此，通过在层状结构中引入相干钙钛矿相作为“铆钉”，我们通过钉住效应显著减轻了有害的结构演变。与传统材料相比，每一次循环的晶格应变演化减少了近70%，形态完整性得到增强，从而显著提高电池的循环性能。
这种抗应变的方法拓宽了晶格工程的前景，以释放锂（脱）插层产生的应变，并为开发具有长期耐久性的高能量密度阴极铺平道路。
▲ Abstract：
Here, by introducing a coherent perovskite phase into the layered structure functioning as a ‘rivet’, we significantly mitigate the pernicious structural evolutions by a pinning effect. The lattice strain evolution in every single cycle is markedly reduced by nearly 70% when compared with conventional materials, which significantly enhances morphological integrity leading to a notable improvement in battery cyclability. This strain-retardant approach broadens the perspective for lattice engineering to release the strain raised from lithium (de)intercalation and paves the way for the development of high-energy-density cathodes with long durability.
机械工程
Mechanical Engineering
3D-printed machines that manipulate microscopic objects using capillary forces
利用表面张力操纵微观物体的3D打印机器
▲ 作者：Cheng Zeng, Maya Winters Faaborg, Ahmed Sherif et al.
▲ 链接：
https://www.nature.com/articles/s41586-022-05234-7
▲ 摘要：
在此，我们动态调节表面张力在可编程的二维模式中移动物体。我们的3D打印设备包含通道，利用排斥表面张力捕获漂浮物体，然后在水池中垂直移动这些设备。由于通道的横截面随高度的变化而变化，物体可以在二维方向上转动。
由此，该装置和接口构成了一个简单的机器，将垂直运动转换为横向运动。我们设计的机器可以平移、旋转和分离多个浮子，并通过循环垂直运动对水下物体做功。
我们将这些基本的机器组合起来制成厘米级机器，该机器可以将微米级的细丝编织成规定的拓扑结构，包括非重复编织。这种方法可用于操作微米级粒子或编织高频电子产品的材料。
▲ Abstract：
Here we dynamically modulate these forces to move objects in programmable two-dimensional patterns. We 3D-print devices containing channels that trap floating objects using repulsive capillary forces, then move these devices vertically in a water bath. Because the channel cross-sections vary with height, the trapped objects can be steered in two dimensions. The device and interface therefore constitute a simple machine that converts vertical to lateral motion. We design machines that translate, rotate and separate multiple floating objects and that do work on submerged objects through cyclic vertical motion. We combine these elementary machines to make centimetre-scale compound machines that braid micrometre-scale filaments into prescribed topologies, including non-repeating braids. This approach could be used to manipulate micrometre-scale particles or to braid microwires for high-frequency electronics.
地球科学
Geoscience
Volcanic trigger of ocean deoxygenation during Cordilleran ice sheet retreat
科迪勒拉冰盖消退引发火山喷发影响海洋脱氧
▲ 作者：Jianghui Du, Alan C. Mix, Brian A. Haley, Christina L. Belanger & Sharon
▲ 链接：
https://www.nature.com/articles/s41586-022-05267-y
▲ 摘要：
在此，我们发现科迪勒拉冰盖（CIS）消退后北太平洋的最初脱氧与海底沉积物中火山灰的增加有关。火山喷发相对于CIS消退的时间表明，区域爆发火山活动是由冰下压引起的。
我们认为，在CIS消退期间，火山灰的铁肥化了这一区域的海洋，助长生物生产力，促使海洋系统持续脱氧。我们还发现了过去约5万年中与冰盖消退有关的、更古老的脱氧事件。
我们的研究结果表明，大气、海洋、冰冻圈和地球土壤系统之间的复杂耦合发生在相对短的时间尺度上，可能是海洋生物化学变化的重要驱动因素。
▲ Abstract：
Here we find that initial deoxygenation in the North Pacific immediately after the Cordilleran ice sheet (CIS) retreat was associated with increased volcanic ash in seafloor sediments. Timing of volcanic inputs relative to CIS retreat suggests that regional explosive volcanism was initiated by ice unloading. We posit that iron fertilization by volcanic ash during CIS retreat fuelled ocean productivity in this otherwise iron-limited region, and tipped the marine system towards sustained deoxygenation. We also identify older deoxygenation events linked to CIS retreat over the past approximately 50,000 years. Our findings suggest that the apparent coupling between the atmosphere, ocean, cryosphere and solid-Earth systems occurs on relatively short timescales and can act as an important driver for ocean biogeochemical change.
Global trends of cropland phosphorus use and sustainability challenges
全球农田磷利用趋势与可持续发展挑战
▲ 作者：T. Zou, X. Zhang & E. A. Davidson
▲ 链接：
https://www.nature.com/articles/s41586-022-05220-z
▲ 摘要：
在此，我们提供了1961-2019年间按国家和作物类型划分的磷预算（作物生产系统的投入和产出）和磷利用效率（PUE）数据库，并研究了几个驱动因素对磷利用效率的重大贡献，如经济发展阶段和作物组合。
为了应对磷管理的挑战，我们发现全球作物生产的磷利用效率必须增加到68-81%，而最近的趋势表明我们在实现这一目标方面取得了有意义的进展。然而，各国农田磷肥管理面临的挑战和机遇却大不相同。
▲ Abstract：
Here we present a database of the phosphorus (P) budget (the input and output of the crop production system) and PUE by country and by crop type for 1961–2019, and examine the substantial contribution of several drivers for PUE, such as economic development stages and crop portfolios. To address the P management challenges, we found that global PUE in crop production must increase to 68–81%, and recent trends indicate some meaningful progress towards this goal. However, P management challenges and opportunities in croplands vary widely among countries.
Calcium dissolution in bridgmanite in the Earth's deep mantle
地球深部地幔桥锰矿中的钙溶解
▲ 作者：Byeongkwan Ko, Eran Greenberg, Vitali Prakapenka, E. Ercan Alp, Wenli Bi, Yue Meng, Dongzhou Zhang & Sang-Heon Shim
▲ 链接：
https://www.nature.com/articles/s41586-022-05237-4
▲ 摘要：
在此，我们的实验表明，钙在桥锰矿中的溶解度在2300 K和超过40 GPa时急剧增加，达到一个足以使桥锰矿中的所有硅酸钙成分完全溶解其中的水平，导致在沿地热深度超过1800公里处没有硅酸钙钙钛矿。
因此，我们提出从双钙钛矿结构域（TPD）在较浅的下地幔形成单钙钛矿畴（SPD）。温度驱动的性质可能导致TPD至SPD深度随温度变化而发生巨大的横向变化（超过500公里）。此外，在以前地幔较温暖的时候，SPD应该较厚。
我们的发现提出对深地幔矿物学模型的修正，同时将对理解该区域的组成、结构、动力学和演化产生影响。
▲ Abstract：
Here we experimentally show that the calcium solubility in bridgmanite increases steeply at about 2,300 kelvin and above 40 gigapascals to a level sufficient for a complete dissolution of all CaSiO3 component in pyrolite into bridgmanite, resulting in the disappearance of CaSiO3 perovskite at depths greater than about 1,800 kilometres along the geotherm. Hence we propose a change from a two-perovskite domain (TPD; bridgmanite plus CaSiO3 perovskite) at the shallower lower mantle to a single-perovskite domain (SPD; calcium-rich bridgmanite) at the deeper lower mantle. Iron seems to have a key role in increasing the calcium solubility in bridgmanite. The temperature-driven nature can cause large lateral variations in the depth of the TPD-to-SPD change in response to temperature variations (by more than 500 kilometres). Furthermore, the SPD should have been thicker in the past when the mantle was warmer. Our finding requires revision of the deep-mantle mineralogy models and will have an impact on our understanding of the composition, structure, dynamics and evolution of the region.
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