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论文|Science《自然》20230309——论文导读

日期： 来源：学研录收集编辑：


Nature, 9 March 2023, Volume 615 Issue 7951

《自然》，2023年3月9日，第615卷7951期




物理学Physics








Atomic Bose–Einstein condensate in twisted-bilayer optical lattices

扭曲双分子层光学晶格中的原子玻色-爱因斯坦凝聚

▲ 作者：Zengming Meng, Liangwei Wang, Wei Han, Fangde Liu, Kai Wen, Chao Gao, Pengjun Wang, Cheng Chin & Jing Zhang

▲ 链接：

https://www.nature.com/articles/s41586-023-05695-4


▲ 摘要：

在扭曲双层石墨烯中观察到强相关性和超导性激发了人们对基础物理学和应用物理学的巨大兴趣。基于原子玻色-爱因斯坦凝聚体加载到自旋依赖光学晶格的扭曲双层方晶格中超流体到莫特绝缘体跃迁的研究，作者演示了一个量子模拟。其晶格由两组激光束组成，这些激光束独立地处理处于不同自旋状态的原子，形成容纳两层的合成维度。


层间耦合被微波场高度可控，这使得在强耦合极限中出现最低平坦带和新的相关相位。他们直接观测到空间摩尔图和动量衍射，证实了在扭曲双分子层晶格中存在两种形式的超流体和一种改进的超流体到绝缘体的转变。该方案是通用的，可以应用于不同的晶格几何和玻色子和费米子系统。这为在具有高度可控光学晶格的超冷原子中探索摩尔物理开辟了新的方向。


▲ Abstract：

Observation of strong correlations and superconductivity in twisted-bilayer graphenehas stimulated tremendous interest in fundamental and applied physics. Here we demonstrate a quantum simulation of superfluid to Mott insulator transition in twisted-bilayer square lattices based on atomic Bose–Einstein condensates loaded into spin-dependent optical lattices. The lattices are made of two sets of laser beams that independently address atoms in different spin states, which form the synthetic dimension accommodating the two layers. The interlayer coupling is highly controllable by a microwave field, which enables the occurrence of a lowest flat band and new correlated phases in the strong coupling limit. We directly observe the spatial moiré pattern and the momentum diffraction, which confirm the presence of two forms of superfluid and a modified superfluid to insulator transition in twisted-bilayer lattices. Our scheme is generic and can be applied to different lattice geometries and for both boson and fermion systems. This opens up a new direction for exploring moiré physics in ultracold atoms with highly controllable optical lattices.










Evidence of near-ambient superconductivity in a N-doped lutetium hydride

氮掺杂氢化镥中近环境超导性的证据

▲ 作者：Nathan Dasenbrock-Gammon, Elliot Snider, Raymond McBride, Hiranya Pasan, Dylan Durkee, Nugzari Khalvashi-Sutter, Sasanka Munasinghe, Sachith E. Dissanayake, Keith V. Lawler, Ashkan Salamat & Ranga P. Dias
▲ 链接：
https://www.nature.com/articles/s41586-023-05742-0

▲ 摘要：
超导材料所表现出的无电阻特性在常温常压条件下具有巨大的应用潜力。尽管进行了数十年的密集研究，但这样的状态还没有实现。作者报告了氮掺杂氢化镥在室温和近环境压力下的超导性。该化合物在高压高温条件下合成，在完全回收后，沿压缩路径检测了其材料和超导性能。

这包括有和没有施加磁场的温度依赖性电阻、化(M)与磁场(H)曲线、交流和直流磁化率以及热容测量。X射线衍射、能量色散X射线和理论模拟为合成材料的化学计量学提供了一些见解。然而，还需要进一步的实验和模拟来确定氢和氮的确切化学计量，以及它们各自的原子位置，以更大的努力进一步了解材料的超导状态。

▲ Abstract：
The absence of electrical resistance exhibited by superconducting materials would have enormous potential for applications if it existed at ambient temperature and pressure conditions. Despite decades of intense research efforts, such a state has yet to be realized.Here we report evidence of superconductivity on a nitrogen-doped lutetium hydride with a maximum Tc of 294 K at 10 kbar, that is, superconductivity at room temperature and near-ambient pressures. The compound was synthesized under high-pressure high-temperature conditions and then—after full recoverability—its material and superconducting properties were examined along compression pathways. These include temperature-dependent resistance with and without an applied magnetic field, the magnetization (M) versus magnetic field (H) curve, a.c. and d.c. magnetic susceptibility, as well as heat-capacity measurements. X-ray diffraction (XRD), energy-dispersive X-ray (EDX) and theoretical simulations provide some insight into the stoichiometry of the synthesized material. Nevertheless, further experiments and simulations are needed to determine the exact stoichiometry of hydrogen and nitrogen, and their respective atomistic positions, in a greater effort to further understand the superconducting state of the material.






地球物理学和地球化学

Geophysics & Geochemistry








Chlorine activation and enhanced ozone depletion induced by wildfire aerosol

野火气溶胶引起的氯活化增强臭氧消耗

▲ 作者：Susan Solomon, Kane Stone, Pengfei Yu, D. M. Murphy, Doug Kinnison, A. R. Ravishankara & Peidong Wang
▲ 链接：
https://www.nature.com/articles/s41586-022-05683-0

▲ 摘要：
在2020年澳大利亚野火之后，在南半球中纬度地区观测到的平流层氯物种和臭氧丰度显著扰动。这些大气化学成分的变化表明，野火气溶胶影响平流层氯和臭氧消耗化学。

研究者提出，含有氧化有机物和硫酸盐混合物的野火气溶胶增加了盐酸的溶解度和相关的多相反应速率，激活了活性氯物种，并在相对温暖的平流层温度下提高了臭氧损失率。他们通过将大气观测结果与包含所提出机制的模型模拟进行比较来验证其假设。2020年盐酸、硝酸氯和次氯酸丰度的模拟变化与观测结果非常吻合。

研究结果表明，野火气溶胶化学，虽然没有考虑到2020年南极臭氧空洞的创纪录持续时间，但确实会增加其面积，并使南部中纬度臭氧总柱消耗3%~5%。这些发现增加了人们的担忧，即在全球变暖的情况下，更频繁和更强烈的野火可能会推迟臭氧的恢复。

▲ Abstract：
Remarkable perturbations in the stratospheric abundances of chlorine species and ozone were observed over Southern Hemisphere mid-latitudes following the 2020 Australian wildfires. These changes in atmospheric chemical composition suggest that wildfire aerosols affect stratospheric chlorine and ozone depletion chemistry. Here we propose that wildfire aerosol containing a mixture of oxidized organics and sulfate increases hydrochloric acid solubility and associated heterogeneous reaction rates, activating reactive chlorine species and enhancing ozone loss rates at relatively warm stratospheric temperatures. We test our hypothesis by comparing atmospheric observations to model simulations that include the proposed mechanism. Modelled changes in 2020 hydrochloric acid, chlorine nitrate and hypochlorous acid abundances are in good agreement with observations. Our results indicate that wildfire aerosol chemistry, although not accounting for the record duration of the 2020 Antarctic ozone hole, does yield an increase in its area and a 3–5% depletion of southern mid-latitude total column ozone. These findings increase concern that more frequent and intense wildfires could delay ozone recovery in a warming world.











The evolution of the marine carbonate factory

海洋碳酸盐工厂的演化

▲ 作者：Jiuyuan Wang, Lidya G. Tarhan, Andrew D. Jacobson, Amanda M. Oehlert & Noah J. Planavsky
▲ 链接：
https://www.nature.com/articles/s41586-022-05654-5

▲ 摘要：
碳酸钙的形成是碳从海洋-大气系统返回固体地球的主要途径。碳酸盐矿物的沉淀对海水中溶解的无机碳的去除在形成海洋生物地球化学循环中起着至关重要的作用。由于缺乏经验约束，对于海洋碳酸盐工厂如何随时间变化的观点存在广泛分歧。

研究者利用稳定锶同位素的地球化学见解，为海洋碳酸盐工厂和碳酸盐矿物饱和状态的演化提供了新的视角。尽管在地球历史的大部分时间里，人们普遍认为海洋表层和浅层海底碳酸盐的生成是主要的碳酸盐汇，但他们认为，其他过程——例如自生碳酸盐的孔隙水生成——可能代表了整个前寒武纪的主要碳酸盐汇。研究结果还表明，生物体碳酸盐工厂的兴起降低了海水碳酸盐饱和状态。

▲ Abstract：
Calcium carbonate formation is the primary pathway by which carbon is returned from the ocean–atmosphere system to the solid Earth. The removal of dissolved inorganic carbon from seawater by precipitation of carbonate minerals—the marine carbonate factory—plays a critical role in shaping marine biogeochemical cycling. A paucity of empirical constraints has led to widely divergent views on how the marine carbonate factory has changed over time. Here we use geochemical insights from stable strontium isotopes to provide a new perspective on the evolution of the marine carbonate factory and carbonate mineral saturation states. Although the production of carbonates in the surface ocean and in shallow seafloor settings have been widely considered the predominant carbonate sinks for most of the history of the Earth, we propose that alternative processes—such as porewater production of authigenic carbonates—may have represented a major carbonate sink throughout the Precambrian. Our results also suggest that the rise of the skeletal carbonate factory decreased seawater carbonate saturation states.






生态学Ecology








Tropical deforestation causes large reductions in observed precipitation

热带森林砍伐导致观测到的降水量大幅减少

▲ 作者：C. Smith, J. C. A. Baker & D. V. Spracklen
▲ 链接：
https://www.nature.com/articles/s41586-022-05690-1

▲ 摘要：
热带森林在水文循环中起着关键作用，并可影响局部和区域降水。以前的工作评估了热带森林砍伐对降水的影响，但这些研究在很大程度上仅限于案例研究。对于森林砍伐和降水之间的相互作用（尤其是这种相互作用如何在空间尺度上变化）缺乏更广泛的分析。研究者展示了热带森林砍伐地区降水的减少。

他们的结果来自使用卫星、站基和再分析数据集对2003~2017年森林损失对降水影响的泛热带评估。森林砍伐对降水的影响在更大的尺度上有所增加，卫星数据集显示，森林损失在超过50公里的尺度上导致降水大幅减少。

在研究者所探索的最大范围内，降水降幅最大的是200公里，其中森林损失1个百分点，每月降水量减少0.25±0.1毫米。再分析和基于站点的产品在降水对森林损失的响应方向上存在分歧，他们将其归因于稀疏的热带原位测量。作者估计，刚果未来的森林砍伐将使当地降水在2100年减少8%~10%。该发现为保护热带森林以支持区域气候恢复力提供了令人信服的论据。

▲ Abstract：
Tropical forests play a critical role in the hydrological cycle and can influence local and regional precipitation1. Previous work has assessed the impacts of tropical deforestation on precipitation, but these efforts have been largely limited to case studies2. A wider analysis of interactions between deforestation and precipitation—and especially how any such interactions might vary across spatial scales—is lacking. Here we show reduced precipitation over deforested regions across the tropics. Our results arise from a pan-tropical assessment of the impacts of 2003–2017 forest loss on precipitation using satellite, station-based and reanalysis datasets. The effect of deforestation on precipitation increased at larger scales, with satellite datasets showing that forest loss caused robust reductions in precipitation at scales greater than 50 km. The greatest declines in precipitation occurred at 200 km, the largest scale we explored, for which 1 percentage point of forest loss reduced precipitation by 0.25 ± 0.1 mm per month. Reanalysis and station-based products disagree on the direction of precipitation responses to forest loss, which we attribute to sparse in situ tropical measurements. We estimate that future deforestation in the Congo will reduce local precipitation by 8–10% in 2100. Our findings provide a compelling argument for tropical forest conservation to support regional climate resilience.











Coastal phytoplankton blooms expand and intensify in the 21st century

21世纪沿海浮游植物加剧

▲ 作者：Yanhui Dai, Shangbo Yang, Dan Zhao, Chuanmin Hu, Wang Xu, Donald M. Anderson, Yun Li, Xiao-Peng Song, Daniel G. Boyce, Luke Gibson, Chunmiao Zheng & Lian Feng
▲ 链接：
https://www.nature.com/articles/s41586-023-05760-y

▲ 摘要：
沿海海洋的浮游植物大量繁殖有利于沿海渔业生产和生态系统功能，但也可能导致重大的环境问题，然而，在全球范围内还没有关于浮游植物大量繁殖的详细描述。研究者使用1公里空间分辨率的全球卫星观测，绘制了2003年至2020年期间每天的海洋沿海藻类繁殖图。

他们发现，在被调查的153个沿海国家中，有126个发生了藻华。在全球范围内，藻华的空间范围（+13.2%）和频率（+59.2%）在研究期间显著增加（P < 0.05），而在北半球热带和亚热带地区开花减弱。研究者记录了藻华趋势与海洋环流之间的关系，并确定了最近海洋表面温度升高的刺激效应。

他们表示，每日绘制的沿海浮游植物华值的汇编为全球华值风险和效益评估以及管理或政策行动的制定或评估提供了基础。

▲ Abstract：
Phytoplankton blooms in coastal oceans can be beneficial to coastal fisheries production and ecosystem function, but can also cause major environmental problems—yet detailed characterizations of bloom incidence and distribution are not available worldwide. Here we map daily marine coastal algal blooms between 2003 and 2020 using global satellite observations at 1-km spatial resolution. We found that algal blooms occurred in 126 out of the 153 coastal countries examined. Globally, the spatial extent (+13.2%) and frequency (+59.2%) of blooms increased significantly (P < 0.05) over the study period, whereas blooms weakened in tropical and subtropical areas of the Northern Hemisphere. We documented the relationship between the bloom trends and ocean circulation, and identified the stimulatory effects of recent increases in sea surface temperature. Our compilation of daily mapped coastal phytoplankton blooms provides the basis for global assessments of bloom risks and benefits, and for the formulation or evaluation of management or policy actions.





—END—


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