2023/5/29 8:48:42 阅读：61 发布者：
Nature, 18 May 2023, Volume 617 Issue 7961
《自然》2023年5月18日，第617卷，7961期
天文学Astronomy
A radio-detected type Ia supernova with helium-rich circumstellar material
由无线电探测到的、具有富氦星周物质的Ia型超新星
▲ 作者：Erik C. Kool, Joel Johansson, Jesper Sollerman et al.
▲ 链接：
https://www.nature.com/articles/s41586-023-05916-w
▲ 摘要：
在此，我们报告关于SN 2020eyj的研究。根据它的光谱特征、红外发射以及射电对应物（迄今为止第一次在Ia型超新星中发现），SN 2020eyj是一颗富氦的Ia型超新星。
根据模型，我们认为，星周物质可能来自一个单简并双星系统。在这个系统中，白矮星从氦供体恒星吸积物质，这是一种Ia型超新星常见的形成途径。同时，我们阐述了类似SN 2020eyj的Ia型超新星的综合无线电跟踪如何改善来自始祖星系的约束。
▲ Abstract：
Here we report on the study of SN 2020eyj, a SN Ia showing helium-rich circumstellar material, as demonstrated by its spectral features, infrared emission and, for the first time in a SN Ia to our knowledge, a radio counterpart. On the basis of our modelling, we conclude that the circumstellar material probably originates from a single-degenerate binary system in which a white dwarf accretes material from a helium donor star, an often proposed formation channel for SNe Ia. We describe how comprehensive radio follow-up of SN 2020eyj-like SNe Ia can improve the constraints on their progenitor systems.
材料科学Material science
Photochromism from wavelength-selective colloidal phase segregation
波长选择性胶体相偏析的光致变色
▲ 作者：Jing Zheng, Jingyuan Chen, Yakang Jin et al.
▲ 链接：
https://www.nature.com/articles/s41586-023-05873-4
▲ 摘要：
在这项工作中，我们设计了一个简单的光谱选择性活性胶体系统，其中二氧化钛胶体粒子用光谱特征染料编码，形成光致变色胶体群。在这个系统中，通过组合不同波长和强度的入射光可以调节粒子-粒子的相互作用，从而实现可控的胶体聚集和分离。
此外，通过混合青色、品红和黄色胶体，可以形成动态的光致变色胶体群。在有色光的照明下，由于层状相分离，胶体群适应入射光的外观，为彩色电子纸和自供电光学伪装提供了一种更加简便的解决方法。
▲ Abstract：
In this work, we design a simple spectral selective active colloidal system, in which TiO2 colloidal species were coded with spectral distinctive dyes to form a photochromic colloidal swarm. In this system, the particle–particle interactions can be programmed by combining incident light with various wavelengths and intensities to enable controllable colloidal gelation and segregation. Furthermore, by mixing the cyan, magenta and yellow colloids, a dynamic photochromic colloidal swarm is formulated. On illumination of coloured light, the colloidal swarm adapts the appearance of incident light due to layered phase segregation, presenting a facile approach towards coloured electronic paper and self-powered optical camouflage.
A 3D printable alloy designed for extreme environments
一款为极端环境设计的3D打印合金
▲ 作者：Timothy M. Smith, Christopher A. Kantzos, Nikolai A. Zarkevich et al.
▲ 链接：
https://www.nature.com/articles/s41586-023-05893-0
▲ 摘要：
通过对其微观结构的高分辨率表征，我们展示了纳米级氧化物在GRX-810构建体积中的成功组合和分离。在1093℃的高温下，与广泛用于增材制造的传统多晶变形镍基合金相比，GRX-810合金的强度提高了2倍，蠕变性能提高了1000倍以上，抗氧化性能提高了2倍。
这种合金的成功强调了，与过去的试错法相比，模型驱动合金设计可以使用更少的资源同时提供更优越的结果。这些结果表明，利用弥散强化与增材制造工艺相结合的未来合金开发可以加速革命性材料的发现。
▲ Abstract：
We show the successful incorporation and dispersion of nanoscale oxides throughout the GRX-810 build volume via high-resolution characterization of its microstructure. The mechanical results of GRX-810 show a twofold improvement in strength, over 1,000-fold better creep performance and twofold improvement in oxidation resistance compared with the traditional polycrystalline wrought Ni-based alloys used extensively in additive manufacturing at 1,093 °C. The success of this alloy highlights how model-driven alloy designs can provide superior compositions using far fewer resources compared with the ‘trial-and-error’ methods of the past. These results showcase how future alloy development that leverages dispersion strengthening combined with additive manufacturing processing can accelerate the discovery of revolutionary materials.
化学Chemistry
CO2-mediated organocatalytic chlorine evolution under industrial conditions
工业条件下二氧化碳介导的有机催化氯析出
▲ 作者：Jiarui Yang, Wen-Hao Li, Hai-Tao Tang, Ying-Ming Pan, Dingsheng Wang & Yadong Li
▲ 链接：
https://www.nature.com/articles/s41586-023-05886-z
▲ 摘要：
在此，我们展示了带酰胺官能团的有机催化剂可以使氯析出反应；在有二氧化碳的情况下，它在过电位仅为89 毫伏时，电流密度为10 kA m−2且选择性为99.6%，因此可以与尺寸稳定的阳极相媲美。
我们发现二氧化碳与酰胺氮的可逆结合促进了自由基的形成，这种自由基在氯气的生成中起关键作用，在氯电池和有机合成时也可能起效。虽然有机催化剂通常不被认为有希望用于苛刻的电化学应用，但这项工作证明了它们具备更广泛的潜力，以及为开发工业相关的新工艺和探索新的电化学机制提供机会。
▲ Abstract：
Here we show that an organocatalyst with an amide functional group enables the chlorine evolution reaction; and that in the presence of CO2, it achieves a current density of 10 kA m−2 and a selectivity of 99.6% at an overpotential of only 89 mV and thus rivals the dimensionally stable anode. We find that reversible binding of CO2 to the amide nitrogen facilitates formation of a radical species that plays a critical role in Cl2 generation, and that might also prove useful in the context of Cl− batteries and organic synthesis. Although organocatalysts are typically not considered promising for demanding electrochemical applications, this work demonstrates their broader potential and the opportunities they offer for developing industrially relevant new processes and exploring new electrochemical mechanisms.
The electron–proton bottleneck of photosynthetic oxygen evolution
光合氧进化的电子-质子瓶颈
▲ 作者：Paul Greife, Matthias Schönborn, Matteo Capone, Ricardo Assunção, Daniele Narzi, Leonardo Guidoni & Holger Dau
▲ 链接：
https://www.nature.com/articles/s41586-023-06008-5
▲ 摘要：
在此，我们解决了光合氧进化成的关键阶段及其关键的机制作用。我们用微秒红外光谱技术跟踪了23万个暗适应光系统的激发周期。通过将这些结果与计算化学相结合，我们揭示了一个关键的质子空位最初是通过门控侧链去质子化产生的。
随后，在单电子、多质子转移事件中形成活性氧自由基。这是光合作用O2形成过程中最慢的一个步骤，有中度的能量屏障和明显的熵减慢。我们将S4态确定为氧自由基态；它的形成之后则是快速的O-O键合及O2释放。结合先前在实验和计算研究方面的突破，一幅引人注目的光合作用O2形成的原子图出现了。
我们的研究结果提供了对过去30亿年可能发生的生物过程的见解，我们希望这能够支持基于知识的人工水分解系统设计。
▲ Abstract：
Here we resolve this key stage of photosynthetic O2 formation and its crucial mechanistic role. We tracked 230,000 excitation cycles of dark-adapted photosystems with microsecond infrared spectroscopy. Combining these results with computational chemistry reveals that a crucial proton vacancy is initally created through gated sidechain deprotonation. Subsequently, a reactive oxygen radical is formed in a single-electron, multi-proton transfer event. This is the slowest step in photosynthetic O2 formation, with a moderate energetic barrier and marked entropic slowdown. We identify the S4 state as the oxygen-radical state; its formation is followed by fast O–O bonding and O2 release. In conjunction with previous breakthroughs in experimental and computational investigations, a compelling atomistic picture of photosynthetic O2 formation emerges. Our results provide insights into a biological process that is likely to have occurred unchanged for the past three billion years, which we expect to support the knowledge-based design of artificial water-splitting systems.
生物学Biology
Testosterone histories from tusks reveal woolly mammoth musth episodes
象牙的睾丸素历史揭示了猛犸象的发情期狂暴
▲ 作者：Michael D. Cherney, Daniel C. Fisher, Richard J. Auchus et al.
▲ 链接：
https://www.nature.com/articles/s41586-023-06020-9
▲ 摘要：
在此，我们使用液相色谱串联质谱与精细尺度连续采样配对测量了现代象牙与象牙化石中的类固醇激素浓度。成年雄性非洲象的象牙显示出睾丸激素的周期性增加，这表明发情期狂暴的发作。
发情期狂暴是一种每年反复出现的行为和生理变化，可以提高交配成功率。对一头雄性猛犸象象牙的平行评估表明，它也经历过发情期狂暴。这些结果为使用保存在牙本质中的类固醇来研究现代和灭绝哺乳动物的发育、繁殖和应激的广泛研究奠定了基础。
由于牙本质通常含有生长线，牙齿比其他组织更有优势，可以作为内分泌数据的记录。鉴于分析精度所需的牙本质粉末质量低，我们预计牙本质激素研究可以扩展到体型更小的动物。除了在动物学和古生物学中的广泛应用外，牙齿激素记录还可以支持医学、法医、兽医和考古的研究。
▲ Abstract：
Here we use liquid chromatography with tandem mass spectrometry paired with fine-scale serial sampling to measure steroid hormone concentrations in modern and fossil tusk dentin. An adult male African elephant (Loxodonta africana) tusk shows periodic increases in testosterone that reveal episodes of musth, an annually recurring period of behavioural and physiological changes that enhance mating success. Parallel assessments of a male woolly mammoth (Mammuthus primigenius) tusk show that mammoths also experienced musth. These results set the stage for wide-ranging studies using steroids preserved in dentin to investigate development, reproduction and stress in modern and extinct mammals. Because dentin grows by apposition, resists degradation, and often contains growth lines, teeth have advantages over other tissues that are used as records of endocrine data. Given the low mass of dentin powder required for analytical precision, we anticipate dentin-hormone studies to extend to smaller animals. Thus, in addition to broad applications in zoology and palaeontology, tooth hormone records could support medical, forensic, veterinary and archaeological studies.
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