《自然》（20230824出版）一周论文导读

Nature,  24 August 2023, Volume 620 Issue 7975, 

《自然》2023年8月24日，第620卷，7975期

物理学Physics

Poton transport through nanoscale corrugations in two-dimensional crystalsn

二维晶体中纳米级波纹的质子输运

▲ 作者：O. J. Wahab, E. Daviddi, B. Xin, P. Z. Sun, E. Griffin, A. W. Colburn, D. Barry, M. Yagmurcukardes, F. M. Peeters, A. K. Geim, M. Lozada-Hidalgo & P. R. Unwin

▲ 链接：https://www.nature.com/articles/s41586-023-06247-6

▲ 摘要：

研究者使用高分辨率扫描电化学电池显微镜发现，虽然质子通过机械剥离的单层石墨烯和六方氮化硼的渗透不能归因于任何结构缺陷，但纳米尺度的二维膜的非平坦性极大地促进了质子的运输。

扫描电化学电池显微镜观察到的质子电流的空间分布显示出明显的不均匀性，这种不均匀性与纳米尺度的皱纹和其他应变积累的特征密切相关。

研究结果强调了纳米尺度的形貌是质子通过二维晶体传输的重要参数，二维晶体通常被认为是平面的，并且表明应变和曲率可以作为额外的自由度来控制二维材料的质子渗透率。

▲ Abstract：

Here, using high-resolution scanning electrochemical cell microscopy, we show that, although proton permeation through mechanically exfoliated monolayers of graphene and hexagonal boron nitride cannot be attributed to any structural defects, nanoscale non-flatness of two-dimensional membranes greatly facilitates proton transport. The spatial distribution of proton currents visualized by scanning electrochemical cell microscopy reveals marked inhomogeneities that are strongly correlated with nanoscale wrinkles and other features where strain is accumulated. Our results highlight nanoscale morphology as an important parameter enabling proton transport through two-dimensional crystals, mostly considered and modelled as flat, and indicate that strain and curvature can be used as additional degrees of freedom to control the proton permeability of two-dimensional materials.　

Mixed-dimensional moiré systems of twisted graphitic thin films

扭曲石墨薄膜的混合维涡流系统

▲ 作者：Dacen Waters, Ellis Thompson, Esmeralda Arreguin-Martinez, Manato Fujimoto, Yafei Ren, Kenji Watanabe, Takashi Taniguchi, Ting Cao, Di Xiao & Matthew Yankowitz

▲ 链接：https://www.nature.com/articles/s41586-023-06290-3

▲ 摘要：

将具有相对扭转角的原子薄范德华晶体堆叠形成的摩尔条纹可以产生显着的新物理性质。研究者通过在薄块石墨晶体上轻微旋转单层石墨烯片来构建双门控器件，并对其进行输运测量，发现摩尔流势改变了整个石墨薄膜的电子特性。

在零磁场和小磁场中，输运是由栅极可调谐的摩尔和石墨表面态的组合介导的，以及共存的半金属体态，它们对栅极没有反应。在高场下，由于石墨的两个最低朗道带的独特性质，石墨的摩尔流势与石墨体态发生杂化。

这些朗道带有助于形成单一的准二维杂化结构，在这种杂化结构中，摩尔态和块状石墨态不可避免地混合在一起。研究建立了第一种新型混合维摩尔材料扭曲石墨烯-石墨。

▲ Abstract：

Moiré patterns formed by stacking atomically thin van der Waals crystals with a relative twist angle can give rise to notable new physical properties. Here, we perform transport measurements of dual-gated devices constructed by slightly rotating a monolayer graphene sheet atop a thin bulk graphite crystal. We find that the moiré potential transforms the electronic properties of the entire bulk graphitic thin film. At zero and in small magnetic fields, transport is mediated by a combination of gate-tuneable moiré and graphite surface states, as well as coexisting semimetallic bulk states that do not respond to gating. At high field, the moiré potential hybridizes with the graphitic bulk states due to the unique properties of the two lowest Landau bands of graphite. These Landau bands facilitate the formation of a single quasi-two-dimensional hybrid structure in which the moiré and bulk graphite states are inextricably mixed. Our results establish twisted graphene–graphite as the first in a new class of mixed-dimensional moiré materials.

地理学和地球物理学

Geography & Geophysics

A global rise in alluvial mining increases sediment load in tropical rivers

全球冲积采矿增加热带河流沉积物负荷

▲ 作者：Evan N. Dethier, Miles Silman, Jimena Díaz Leiva, Sarra Alqahtani, Luis E. Fernandez, Paúl Pauca, Seda ?amalan, Peter Tomhave, Francis J. Magilligan, Carl E. Renshaw & David A. Lutz

▲ 链接：

https://www.nature.com/articles/s41586-023-06309-9

▲ 摘要：

全球热带地区河流中越来越多的黄金和矿产开采活动已经导致生态系统退化，并威胁到人类健康。这种河流矿产开采涉及河道走廊的密集挖掘和沉积物处理，改变了河流形态，并向下游释放了多余的沉积物。悬浮沉积物负荷的增加会降低水的清晰度，造成淤积，从而可能导致鱼类患病和死亡、水质恶化和对人类基础设施造成损害。

虽然已在地方尺度上对河流采矿进行了调查，但没有对其实际足迹和对水文系统的影响进行全球综合，因此对其全部环境后果一无所知。研究者收集并分析了一个跨度37年的卫星数据库，显示了全球范围内普遍存在的、不断增加的河流矿产开采。

研究者确定了49个国家的396个矿区，集中在几乎普遍被采矿衍生沉积物改变的热带水道。在173条受采矿影响的河流中，80%的悬浮沉积物浓度是采矿前水平的两倍多。

在采矿影响大型河流（>50米宽）的30个国家中，23±19%的大型河流长度被采矿产生的沉积物改变，这是一个全球性的影响，代表35,000公里的河流，占所有大型热带河流长度的约6%。研究结果强调了热带河流系统中与采矿相关退化的普遍性和强度。

▲ Abstract：

Increasing gold and mineral mining activity in rivers across the global tropics has degraded ecosystems and threatened human health. Such river mineral mining involves intensive excavation and sediment processing in river corridors, altering river form and releasing excess sediment downstream. Increased suspended sediment loads can reduce water clarity and cause siltation to levels that may result in disease and mortality in fish, poor water quality and damage to human infrastructure. Although river mining has been investigated at local scales, no global synthesis of its physical footprint and impacts on hydrologic systems exists, leaving its full environmental consequences unknown. We assemble and analyse a 37-year satellite database showing pervasive, increasing river mineral mining worldwide. We identify 396 mining districts in 49 countries, concentrated in tropical waterways that are almost universally altered by mining-derived sediment. Of 173 mining-affected rivers, 80% have suspended sediment concentrations (SSCs) more than double pre-mining levels. In 30 countries in which mining affects large (>50m wide) rivers, 23±19% of large river length is altered by mining-derived sediment, a globe-spanning effect representing 35,000 river kilometres, 6% (±1%s.e.) of all large tropical river reaches. Our findings highlight the ubiquity and intensity of mining-associated degradation in tropical river systems.

The break of earthquake asperities imaged by distributed acoustic sensing

分布式声传感成像的地震颗粒破碎

▲ 作者：Jiaxuan Li, Taeho Kim, Nadia Lapusta, Ettore Biondi & Zhongwen Zhan

▲ 链接：https://www.nature.com/articles/s41586-023-06227-w

▲ 摘要：

利用全球地震阵列对大逆冲地震进行破裂成像，揭示了与频率相关的破裂特征，但高频辐射作用仍不清楚。对更丰富的地壳地震的类似观测可以提供关键的限制条件，但如果没有超密集的局部阵列，这种情况很少见。

研究者采用分布式声传感技术对高频地震破裂辐射体进行成像。通过将一条100公里长的暗光纤电缆转换成一个10000通道的地震阵列，为2021年美国加州羚羊谷6.0级矩震拍摄了四个高频子事件的图像。

在将研究结果与长周期矩释放和动态破裂模拟进行比较后，作者认为，成像的子事件是由于断层凸起的断裂-断层上更强的点或针-实质上调节了整体破裂行为。在级联序列中，断层凸起的断裂可以促进原本衰落的断裂传播。研究强调了如何利用广泛存在的光纤网络作为高频地震天线，系统地研究区域性中等规模地震的破裂过程。结合动态破裂模型，可以提高对地震破裂动力学的认识。

▲ Abstract：

Rupture imaging of megathrust earthquakes with global seismic arrays revealed frequency-dependent rupture signatures, but the role of high-frequency radiators remains unclear. Similar observations of the more abundant crustal earthquakes could provide critical constraints but are rare without ultradense local arrays. Here we use distributed acoustic sensing technology to image the high-frequency earthquake rupture radiators. By converting a 100-kilometre dark-fibre cable into a 10,000-channel seismic array, we image four high-frequency subevents for the 2021 Antelope Valley, California, moment-magnitude 6.0 earthquake. After comparing our results with long-period moment-release and dynamic rupture simulations, we suggest that the imaged subevents are due to the breaking of fault asperities—stronger spots or pins on the fault—that substantially modulate the overall rupture behaviour. An otherwise fading rupture propagation could be promoted by the breaking of fault asperities in a cascading sequence. This study highlights how we can use the extensive pre-existing fibre networks12 as high-frequency seismic antennas to systematically investigate the rupture process of regional moderate-sized earthquakes. Coupled with dynamic rupture modelling, it could improve our understanding of earthquake rupture dynamics.

生态学Ecology

Landscape-scale benefits of protected areas for tropical biodiversity

热带生物多样性保护区的景观效益

▲ 作者：Jedediah F. Brodie, Jayasilan Mohd-Azlan, Cheng Chen, Oliver R. Wearn, Mairin C. M. Deith, James G. C. Ball, Eleanor M. Slade, David F. R. P. Burslem, Shu Woan Teoh, Peter J. Williams, An Nguyen, Jonathan H. Moore, Scott J. Goetz, Patrick Burns, Patrick Jantz, Christopher R. Hakkenberg, Zaneta M. Kaszta, Sam Cushman, David Coomes, Olga E. Helmy, Glen Reynolds, Jon Paul Rodríguez, Walter Jetz & Matthew Scott Luskin

▲ 链接：https://www.nature.com/articles/s41586-023-06410-z

▲ 摘要：

联合国最近同意大规模扩大全球保护区（PAs），以减缓生物多样性的下降。研究者测试了东南亚巨大多样性的保护区是否有助于其边界内外的脊椎动物保护。保护区增加了鸟类多样性的各个方面。

大型保护区还与邻近未受保护景观中哺乳动物多样性的显著增强有关。研究结果与保护区引发的溢出效应一致，而不是导致其他地方的生态条件恶化。这些发现支持了联合国到2030年实现保护区覆盖率30%的目标，表明保护区在其边界内和更广泛的景观中都与更高的脊椎动物多样性相关。

▲ Abstract：

The United Nations recently agreed to major expansions of global protected areas (PAs) to slow biodiversity declines. Here we test whether PAs across mega-diverse Southeast Asia contribute to vertebrate conservation inside and outside their boundaries. Reserves increased all facets of bird diversity. Large reserves were also associated with substantially enhanced mammal diversity in the adjacent unprotected landscape. Rather than PAs generating leakage that deteriorated ecological conditions elsewhere, our results are consistent with PAs inducing spillover that benefits biodiversity in surrounding areas. These findings support the United Nations goal of achieving 30% PA coverage by 2030 by demonstrating that PAs are associated with higher vertebrate diversity both inside their boundaries and in the broader landscape.

PDiverse values of nature for sustainability

可持续发展的不同自然价值

▲ 作者：Unai Pascual, Patricia Balvanera, Christopher B. Anderson, Rebecca Chaplin-Kramer, Michael Christie, David González-Jiménez, Adrian Martin, Christopher M. Raymond, Mette Termansen, Arild Vatn, Simone Athayde, Brigitte Baptiste,etc

▲ 链接：https://www.nature.com/articles/s41586-023-06406-9

▲ 摘要：

尽管《昆明-蒙特利尔全球生物多样性框架》和联合国可持续发展目标等协议将自然价值观纳入行动，但主流环境和发展政策仍然优先考虑一些价值观，特别是与市场相关的价值观，而忽视了人们与自然联系并从自然中受益的其他方式。可以说，“价值观危机”是生物多样性丧失和气候变化、流行病出现和社会环境不公正等相互交织的危机的基础。

生物多样性和生态系统服务政府间平台在5万多份科学出版物、政策文件以及土著和地方知识来源的基础上，评估了有关自然的各种价值和评估方法的知识，以深入了解它们在政策制定中的作用，并更充分地将其纳入决策。运用这一证据，提出了以价值为中心的方法组合，以提高估值并解决吸收障碍，最终利用变革性变革，实现更公正和可持续的未来。