作者:未玖 来源:科学网微信公众号 发布时间:2023/11/11 20:29:31
选择字号:
《自然》(20231109出版)一周论文导读

 

编译 | 未玖

Nature, 9 November 2023, VOL 623, ISSUE 7986

《自然》2023年11月9日,第623卷,7986期

天文学Astronomy

Phosphorus-bearing molecules PO and PN at the edge of the Galaxy

含磷分子PO和PN位于星系边缘

▲ 作者:L. A. Koelemay, K. R. Gold & L. M. Ziurys

▲ 链接:

https://www.nature.com/articles/s41586-023-06616-1

▲ 摘要:

尽管磷在行星形成和生物学中至关重要,但其只在星系内部12kpc中被识别。不利的原子跃迁在一定程度上阻碍了对磷元素的研究。人们认为磷由大质量恒星中29Si和30Si的中子捕获产生,并通过II型超新星爆炸释放到星际介质中。然而,星系化学演化模型必须任意增加超新星产生以匹配观测到的丰度。

研究组提出了通过PO和PN的毫米光谱检测外部星系气相磷的策略。在距离银河系中心22.6 kpc处的致密云WB89-621观测到PO和PN的旋转线。WB89-621中PO和PN的丰度与太阳系附近的值相当。

外部星系中不存在超新星表明了磷的另一种来源,如“星系喷泉”,即超新星物质通过晕和环星系介质重新分布。然而,在如此远的距离上内尚未发现富含喷泉的云。任何系外来源,如麦哲伦星云,都不太可能富含金属。

磷可能由存在于外部星系的较低质量渐近巨星分支星的中子捕获过程产生。渐近巨星分支星也产生碳,使外推的金属丰度梯度变平,并解释了WB89-621中含碳分子的高丰度。

▲ Abstract:

Despite its importance in planet formation and biology, phosphorus has been identified only in the inner 12 kpc of the Galaxy. The study of this element has been hindered in part by unfavourable atomic transitions. Phosphorus is thought to be created by neutron capture on 29Si and 30Si in massive stars, and released into the interstellar medium by Type II supernova explosions. However, models of galactic chemical evolution must arbitrarily increase the supernovae production to match observed abundances. Here we present the detection of gas-phase phosphorus in the Outer Galaxy through millimetre spectra of PO and PN. Rotational lines of these molecules were observed in the dense cloud WB89-621, located 22.6 kpc from the Galactic Centre. The abundances of PO and PN in WB89-621 are comparable to values near the Solar System. Supernovae are not present in the Outer Galaxy, suggesting another source of phosphorus, such as ‘Galactic Fountains’, where supernova material is redistributed through the halo and circumgalactic medium. However, fountain-enriched clouds are not found at such large distances. Any extragalactic source, such as the Magellanic Clouds, is unlikely to be metal rich. Phosphorus instead may be produced by neutron-capture processes in lower mass asymptotic giant branch stars which are present in the Outer Galaxy. Asymptotic giant branch stars also produce carbon, flattening the extrapolated metallicity gradient and accounting for the high abundances of C-containing molecules in WB89-621.

物理学Physics

Towards linking lab and field lifetimes of perovskite solar cells

钙钛矿太阳能电池的实验室寿命和场寿命的联系

▲ 作者:Qi Jiang, Robert Tirawat, Ross A. Kerner, E. Ashley Gaulding, Yeming Xian, Xiaoming Wang, et al.

▲ 链接:

https://www.nature.com/articles/s41586-023-06610-7

▲ 摘要:

金属卤化物钙钛矿太阳能电池(PSCs)是一种前景广阔的低成本薄膜光伏技术,在单结和串联应用中都具有前所未有的功率转换效率。

为了推动PSC走向商业化,了解器件在多种应力因素(例如光、热和湿度)共存的实际室外条件下的可靠性至关重要,尽管这颇具挑战性,且会产生复杂的降解行为。为快速指导PSC开发,有必要确定加速室内测试协议,该协议可将特定应力源与现场器件中观察到的降解模式关联起来。

研究组使用最先进的正本征负(p-i-n)PSC堆栈(功率转换效率高达约25.5%)来证明室内加速稳定性测试可预测六个月的室外老化测试。光照和高温下的器件降解率对于理解室外器件的可靠性最具指导意义。

研究组还发现氧化铟锡/自组装单层基空穴传输层/钙钛矿界面对该器件的运行稳定性影响最大。改进自组装单层空穴传输层的离子阻断性能可将器件在50℃~85℃下的平均运行稳定性提高约2.8倍,在85℃下超过1000小时,在50℃下接近8200小时,预计降解率为20%,这在迄今为止高效p-i-n PSC的最佳性能之一。

▲ Abstract:

Metal halide perovskite solar cells (PSCs) represent a promising low-cost thin-film photovoltaic technology, with unprecedented power conversion efficiencies obtained for both single-junction and tandem applications. To push PSCs towards commercialization, it is critical, albeit challenging, to understand device reliability under real-world outdoor conditions where multiple stress factors (for example, light, heat and humidity) coexist, generating complicated degradation behaviours. To quickly guide PSC development, it is necessary to identify accelerated indoor testing protocols that can correlate specific stressors with observed degradation modes in fielded devices. Here we use a state-of-the-art positive-intrinsic-negative (p–i–n) PSC stack (with power conversion efficiencies of up to approximately 25.5%) to show that indoor accelerated stability tests can predict our six-month outdoor ageing tests. Device degradation rates under illumination and at elevated temperatures are most instructive for understanding outdoor device reliability. We also find that the indium tin oxide/self-assembled monolayer-based hole transport layer/perovskite interface most strongly affects our device operation stability. Improving the ion-blocking properties of the self-assembled monolayer hole transport layer increases averaged device operational stability at 50 °C–85 °C by a factor of about 2.8, reaching over 1,000 h at 85 °C and to near 8,200 h at 50 °C, with a projected 20% degradation, which is among the best to date for high-efficiency p–i–n PSCs.

材料科学Materials Science

Predicting crystal form stability under real-world conditions

预测实际条件下的晶型稳定性

▲ 作者:Dzmitry Firaha, Yifei Michelle Liu, Jacco van de Streek, Kiran Sasikumar, Hanno Dietrich, Julian Helfferich, et al.

▲ 链接:

https://www.nature.com/articles/s41586-023-06587-3

▲ 摘要:

分子晶体的物理化学性质(如溶解度、稳定性、致密性、熔化行为和生物利用度)均取决于它们的晶型。由于精确和可负担的自由能计算的发展,硅晶型选择最近实现在望。

研究组重新定义了当前技术水平,主要是通过提高自由能计算的准确性,构建固体—固体自由能差异的可靠实验基准,量化计算自由能的统计误差,并将不同化学计量的水合物晶体结构和无水晶体结构置于相同的能量图景上,从而定义误差条,来作为温度和相对湿度的函数。

对于工业相关化合物,计算得到的自由能标准误差为1~2 kJ mol−1,并且将具有不同水合物化学计量的晶体结构置于同一能量图景的方法可扩展到其他多组分体系,包括溶剂化物。这些贡献缩小了实验人员需求与现代计算工具能力之间的差距,将晶体结构预测转变为更可靠、更可行的程序,可与实验证据结合使用,来指导晶型选择并建立控制机制。

▲ Abstract:

The physicochemical properties of molecular crystals, such as solubility, stability, compactability, melting behaviour and bioavailability, depend on their crystal form. In silico crystal form selection has recently come much closer to realization because of the development of accurate and affordable free-energy calculations. Here we redefine the state of the art, primarily by improving the accuracy of free-energy calculations, constructing a reliable experimental benchmark for solid–solid free-energy differences, quantifying statistical errors for the computed free energies and placing both hydrate crystal structures of different stoichiometries and anhydrate crystal structures on the same energy landscape, with defined error bars, as a function of temperature and relative humidity. The calculated free energies have standard errors of 1–2 kJ mol−1 for industrially relevant compounds, and the method to place crystal structures with different hydrate stoichiometries on the same energy landscape can be extended to other multi-component systems, including solvates. These contributions reduce the gap between the needs of the experimentalist and the capabilities of modern computational tools, transforming crystal structure prediction into a more reliable and actionable procedure that can be used in combination with experimental evidence to direct crystal form selection and establish control.

化学Chemistry

Observing the primary steps of ion solvation in helium droplets

观测氦液滴中离子溶剂化的基本步骤

▲ 作者:Simon H. Albrechtsen, Constant A. Schouder, Alberto Viñas Muñoz, Jeppe K. Christensen, Christian Engelbrecht Petersen, Martí Pi, et al.

▲ 链接:

https://www.nature.com/articles/s41586-023-06593-5

▲ 摘要:

溶剂化是自然科学中普遍存在的现象。在宏观层面上,通过热力学和化学反应动力学可以很好地理解溶剂化。在原子水平上,溶剂化的主要步骤是溶剂的单个分子或原子与溶质的分子或离子的吸引和结合。然而,这些步骤从未实时观察到。

研究组在液氦纳米液滴表面实时创建一个钠离子,并测量连续附着到离子上的溶剂原子数量随时间的变化。结果发现前5个氦原子的结合动力学可用泊松过程很好地描述,其结合速率为2.0个原子/皮秒。该速率与溶剂化过程的时间依赖密度泛函理论模拟一致。

此外,该测量还能估计出钠离子周围区域移除的能量随时间的变化,并揭示了总溶剂化能量的一半在4皮秒后耗散。这种实验方法为离子溶剂化的基准理论模型和阳离子—分子复合物形成的时间分辨测量提供了新途径。

▲ Abstract:

Solvation is a ubiquitous phenomenon in the natural sciences. At the macroscopic level, it is well understood through thermodynamics and chemical reaction kinetics. At the atomic level, the primary steps of solvation are the attraction and binding of individual molecules or atoms of a solvent to molecules or ions of a solute. These steps have, however, never been observed in real time. Here we instantly create a single sodium ion at the surface of a liquid helium nanodroplet, and measure the number of solvent atoms that successively attach to the ion as a function of time. We found that the binding dynamics of the first five helium atoms is well described by a Poissonian process with a binding rate of 2.0 atoms per picosecond. This rate is consistent with time-dependent density-functional-theory simulations of the solvation process. Furthermore, our measurements enable an estimate of the energy removed from the region around the sodium ion as a function of time, revealing that half of the total solvation energy is dissipated after four picoseconds. Our experimental method opens possibilities for benchmarking theoretical models of ion solvation and for time-resolved measurements of cation–molecule complex formation.

地球科学Earth Science

Rock organic carbon oxidation CO2 release offsets silicate weathering sink

岩石有机碳氧化CO2 释放抵消硅酸盐风化碳汇

▲ 作者:Jesse R. Zondervan, Robert G. Hilton, Mathieu Dellinger, Fiona J. Clubb, Tobias Roylands & Mateja Ogri?

▲ 链接:

https://www.nature.com/articles/s41586-023-06581-9

▲ 摘要:

山脉抬升和侵蚀调节了地球内部和大气之间的碳平衡,此前研究聚焦于硅酸盐矿物风化在吸收CO2中的作用及其对地球气候稳定在宜居状态的贡献。然而,风化也可以释放CO2,因为岩石有机碳(OCpetro)在近地表被氧化;这种重要的地质CO2通量尚未被很好地约束。

研究组将微量元素铼与空间外推模型相结合,以量化全球河流集水区的CO2通量。结果发现近地表岩石中OCpetro因风化作用每年释放出6800万吨的CO2,与全球范围内硅酸盐风化吸收的CO2相当,甚至超过了这一水平。

CO2释放热点分布在抬升率高且暴露出细粒沉积岩的山脉,如喜马拉雅山脉东部、落基山脉和安第斯山脉。该研究结果表明,OCpetro远非惰性,并导致该区域的风化成为CO2的净源或净汇。

这就提出了一些尚未深入研究的问题,即侵蚀和风化如何驱动长期碳循环,并促进大气圈、生物圈和岩石圈之间碳通量的微妙平衡。

▲ Abstract:

Mountain uplift and erosion have regulated the balance of carbon between Earth’s interior and atmosphere, where prior focus has been placed on the role of silicate mineral weathering in CO2 drawdown and its contribution to the stability of Earth’s climate in a habitable state. However, weathering can also release CO2 as rock organic carbon (OCpetro) is oxidized at the near surface; this important geological CO2 flux has remained poorly constrained. We use the trace element rhenium in combination with a spatial extrapolation model to quantify this flux across global river catchments. We find a CO2 release of 68 megatons of carbon annually from weathering of OCpetro in near-surface rocks, rivalling or even exceeding the CO2 drawdown by silicate weathering at the global scale. Hotspots of CO2 release are found in mountain ranges with high uplift rates exposing fine-grained sedimentary rock, such as the eastern Himalayas, the Rocky Mountains and the Andes. Our results demonstrate that OCpetro is far from inert and causes weathering in regions to be net sources or sinks of CO2. This raises questions, not yet fully studied, as to how erosion and weathering drive the long-term carbon cycle and contribute to the fine balance of carbon fluxes between the atmosphere, biosphere and lithosphere.

Earth’s early continental crust formed from wet and oxidizing arc magmas

地球早期的大陆地壳由湿氧化弧岩浆形成

▲ 作者:Rong-Feng Ge, Simon A. Wilde, Wen-Bin Zhu & Xiao-Lei Wang

▲ 链接:

https://www.nature.com/articles/s41586-023-06552-0

▲ 摘要:

大陆地壳的形成塑造了地球的表面和内部,并产生了我们赖以生存的土地和矿产资源。然而,地球早期大陆地壳如何形成仍存在争议。现代大陆地壳主要由俯冲带的湿氧化弧岩浆形成,其中海洋岩石圈和水循环进入地幔。然而,由于普遍变质作用,构成早期大陆地壳的古岩石的岩浆水含量和氧化还原状态难以量化。

研究组结合两个锆石氧压计,同时测定了主宰早期大陆地壳的太古宙(40~25亿年前)花岗岩类的岩浆氧逸度(fO2)和H2O含量。结果表明,大多数太古宙花岗岩类岩浆的氧化性比太古宙环境地幔源岩浆高1 log单位,岩浆H2O含量高(6~10 wt%),H2O/Ce比值高(>1000),与现代弧岩浆相似。

研究组发现太古宙花岗岩类岩浆的fO2、H2O含量和H2O/Ce比值与岩浆形成深度呈正相关,需要将大量H2O输送到下地壳和地幔。这些观测结果很容易用俯冲作用来解释,但很难与地壳形成的非俯冲模型相协调。研究组注意到40~36亿年前岩浆fO2和H2O含量的增加,可能表明该时期是俯冲的开始时间。

▲ Abstract:

Formation of continental crust has shaped the surface and interior of our planet and generated the land and mineral resources on which we rely. However, how the early continental crust of Earth formed is still debated. Modern continental crust is largely formed from wet and oxidizing arc magmas at subduction zones, in which oceanic lithosphere and water recycle into the mantle. The magmatic H2O content and redox state of ancient rocks that constitute the early continental crust, however, are difficult to quantify owing to ubiquitous metamorphism. Here we combine two zircon oxybarometers to simultaneously determine magmatic oxygen fugacity (fO2) and H2O content of Archaean (4.0–2.5 billion years ago) granitoids that dominate the early continental crust. We show that most Archaean granitoid magmas were ≥1 log unit more oxidizing than Archaean ambient mantle-derived magmas and had high magmatic H2O contents (6–10 wt%) and high H2O/Ce ratios (>1,000), similar to modern arc magmas. We find that magmatic fO2, H2O contents and H2O/Ce ratios of Archaean granitoids positively correlate with depth of magma formation, requiring transport of large amounts of H2O to the lower crust and mantle. These observations can be readily explained by subduction but are difficult to reconcile with non-subduction models of crustal formation. We note an increase in magmatic fO2and H2O content between 4.0 and 3.6 billion years ago, probably indicating the onset of subduction during this period.

 
特别声明:本文转载仅仅是出于传播信息的需要,并不意味着代表本网站观点或证实其内容的真实性;如其他媒体、网站或个人从本网站转载使用,须保留本网站注明的“来源”,并自负版权等法律责任;作者如果不希望被转载或者联系转载稿费等事宜,请与我们接洽。
 
 打印  发E-mail给: 
    
 
相关新闻 相关论文

图片新闻
冰表面长啥样?原子级分辨图像揭晓答案 北方中纬高频雷达网发布首批科学探测结果
“双星计划”:开启中国空间科学新纪元 河西走廊内陆河出山径流研究揭示新趋势
>>更多
 
一周新闻排行
 
编辑部推荐博文