编译|李言
Nature, 10 October 2024, Volume 634 Issue 8033
《自然》2024年10月10日，第634卷，8033期
化学Chemistry
Direct evidence for a carbon–carbon one-electron σ-bond
碳碳单电子σ键的直接证据
▲ 作者：Takuya Shimajiri, Soki Kawaguchi, Takanori Suzuki & Yusuke Ishigaki
▲ 链接：
https://www.nature.com/articles/s41586-024-07965-1
▲ 摘要：
在此，我们报告用具有细长C-C单键的烃的单电子氧化法分离碳原子间单电子σ键的化合物。通过单晶x射线衍射分析和拉曼光谱分析证实了100 K时C-C单电子σ键（2.921(3)?）的存在，并通过密度泛函理论计算证实了该键的存在。
本文的结果明确地证明了近一个世纪前假设的C-C单电子σ键的存在，从而可以期望通过探索成键和非成键状态之间的边界，为进一步发展化学的不同领域铺平道路。
▲ Abstract：
Here we report the isolation of a compound with a one-electron σ-bond between carbon atoms by means of the one-electron oxidation of a hydrocarbon with an elongated C–C single bond. The presence of the C·C one-electron σ-bond (2.921(3)?? at 100?K) was confirmed experimentally by single-crystal X-ray diffraction analysis and Raman spectroscopy, and theoretically by density functional theory calculations. The results of this paper unequivocally demonstrate the existence of a C·C one-electron σ-bond, which was postulated nearly a century ago, and can thus be expected to pave the way for further development in different areas of chemistry by probing the boundary between bonded and non-bonded states.
Synthesis of non-canonical amino acids through dehydrogenative tailoring
脱氢剪裁法合成非规范氨基酸
▲ 作者：Xin Gu, Yu-An Zhang et al.
▲ 链接：
https://www.nature.com/articles/s41586-024-07988-8
▲ 摘要：
在此，我们公开了一种将脂肪族氨基酸转化为结构多样的类似物的逐步脱氢方法。该方法成功的关键在于开发了一种由光化学照射驱动的选择性催化无受体脱氢方法，为下游功能化提供了末端烯烃中间体的途径。
总的来说，这种策略能够快速合成新的氨基酸构建块，并为后期修饰更复杂的寡肽提供了可能性。
▲ Abstract：
Here we disclose a stepwise dehydrogenative method to convert aliphatic amino acids into structurally diverse analogues. The key to the success of this approach lies in the development of a selective catalytic acceptorless dehydrogenation method driven by photochemical irradiation, which provides access to terminal alkene intermediates for downstream functionalization. Overall, this strategy enables the rapid synthesis of new amino acid building blocks and suggests possibilities for the late-stage modification of more complex oligopeptides.
材料科学Material Sciences
Using both faces of polar semiconductor wafers for functional devices
使用极性半导体晶圆的两面用于功能器件
▲ 作者：Len van Deurzen, Eungkyun Kim et al.
▲ 链接：
https://www.nature.com/articles/s41586-024-07983-z
▲ 摘要：
在这项研究中，我们引入了双电子学，表明在同一半导体晶圆的阳离子面上制造光子器件和阴离子面上制造电子器件是可能的。
这带来了在单一结构中利用极性半导体的两面的可能性，其中电子、光子和声学特性可以在同一晶圆的相对面上实现，显著增强了这种革命性半导体家族的功能。
▲ Abstract：
In this work, we introduce dualtronics, showing that it is possible to make photonic devices on the cation face and electronic devices on the anion face of the same semiconductor wafer. This opens the possibility for making use of both faces of polar semiconductors in a single structure, in which electronic, photonic and acoustic properties can be implemented on opposite faces of the same wafer, markedly enhancing the functional capabilities of this revolutionary semiconductor family.
物理学Physics
Multi-qubit gates and Schr?dinger cat states in an optical clock
光学时钟中的多量子位门和薛定谔猫状态
▲ 作者：Alec Cao, William J. Eckner et al.
▲ 链接：
https://www.nature.com/articles/s41586-024-07913-z
▲ 摘要：
在此，我们开发并使用一系列多量子位里德堡门来生成Greenberger–Horne–Zeilinger（GHZ）类型的薛定谔猫状态，在可编程原子阵列中具有多达9个光时钟量子位。在足够短的黑暗时间下的原子激光比较中，我们使用最多四个量子比特的GHZ状态证明了低于标准量子极限（SQL）的分数频率不稳定性。
然而，由于它们的动态范围变小，单一尺寸的GHZ态与未纠缠的原子相比在最佳暗时无法提高可实现的时钟精度。为了克服这一障碍，我们同时准备了一个不同大小的GHZ状态级联，以便在延长的间隔内进行无歧义的相位估计。这些结果展示了接近海森堡有限尺度的光学原子钟精度的关键组成部分。
▲ Abstract：
Here we develop and use a family of multi-qubit Rydberg gates to generate Schr?dinger cat states of the Greenberger–Horne–Zeilinger (GHZ) type with up to nine optical clock qubits in a programmable atom array. In an atom-laser comparison at sufficiently short dark times, we demonstrate a fractional frequency instability below the standard quantum limit (SQL) using GHZ states of up to four qubits. However, because of their reduced dynamic range, GHZ states of a single size fail to improve the achievable clock precision at the optimal dark time compared with unentangled atoms. Towards overcoming this hurdle, we simultaneously prepare a cascade of varying-size GHZ states to perform unambiguous phase estimation over an extended interval. These results demonstrate key building blocks for approaching Heisenberg-limited scaling of optical atomic clock precision.
地球科学Earth Science
Permafrost slows Arctic riverbank erosion
永久冻土减缓了北极河岸的侵蚀
▲ 作者：Emily C. Geyman, Madison M. Douglas et al.
▲ 链接：
https://www.nature.com/articles/s41586-024-07978-w
▲ 摘要：
在此，我们开发了新的计算方法，可以在比卫星图像像素尺寸小5—10倍的长度尺度上检测河岸侵蚀情况。这一创新使得在河流经历水温和流量最大变化的次月时间尺度上量化侵蚀变成可能。
我们使用这些高频观测来约束河岸侵蚀在多大程度上受到热条件限制的程度——这一要求将在永久冻土融化时消失——并与有足够水流以运输构成河岸的沉积物的力学条件进行对比，后者是所有河流都会经历的情况。对阿拉斯加科尤库克河高分辨率数据的分析表明，永久冻土的存在使侵蚀率降低了47%。
通过我们的观测，我们校准并验证了一个可以应用于不同北极河流的数值模型。该模型预测，永久冻土完全融化可能导致北极河流的迁移率增加30%至100%。
▲ Abstract：
Here we develop new computational methods that enable the detection of riverbank erosion at length scales 5–10 times smaller than the pixel size in satellite imagery, an innovation that unlocks the ability to quantify erosion at the sub-monthly timescales when rivers undergo their largest variations in water temperature and flow. We use these high-frequency observations to constrain the extent to which erosion is limited by the thermal condition of melting the pore ice that cements bank sediment, a requirement that will disappear when permafrost thaws, versus the mechanical condition of having sufficient flow to transport the sediment comprising the riverbanks, a condition experienced by all rivers. Analysis of high-resolution data from the Koyukuk River, Alaska, shows that the presence of permafrost reduces erosion rates by 47%. Using our observations, we calibrate and validate a numerical model that can be applied to diverse Arctic rivers. The model predicts that full permafrost thaw may lead to a 30–100% increase in the migration rates of Arctic rivers.
Overconfidence in climate overshoot
对气候过冲过度乐观
▲ 作者：Carl-Friedrich Schleussner, Gaurav Ganti et al.
▲ 链接：
https://www.nature.com/articles/s41586-024-08020-9
▲ 摘要：
在此，我们展示全球和区域气候变化及其相关风险在过冲后与避免过冲后的世界是不同的。
我们发现，与仅稳定全球变暖趋势相比，实现全球气温下降可以限制长期气候风险，包括海平面上升和冰冻圈变化。然而，全球变暖在未来几十年逆转的可能性可能与今天的适应规划相关性有限。强烈的地球系统反馈可能会削弱温度逆转，导致近期和长期持续变暖。
为了对冲和保护高风险后果，我们确定了地球物理对几千亿吨的预防性二氧化碳清除能力的需求。然而，技术、经济和可持续性方面的考虑可能会限制实现这种规模的去除二氧化碳的部署。因此，我们不能确信过冲后的温度下降在今天预期的时间尺度内是可实现的。只有快速的短期减排才能有效降低气候风险。
▲ Abstract：
Here we show that global and regional climate change and associated risks after an overshoot are different from a world that avoids it. We find that achieving declining global temperatures can limit long-term climate risks compared with a mere stabilization of global warming, including for sea-level rise and cryosphere changes. However, the possibility that global warming could be reversed many decades into the future might be of limited relevance for adaptation planning today. Temperature reversal could be undercut by strong Earth-system feedbacks resulting in high near-term and continuous long-term warming. To hedge and protect against high-risk outcomes, we identify the geophysical need for a preventive carbon dioxide removal capacity of several hundred gigatonnes. Yet, technical, economic and sustainability considerations may limit the realization of carbon dioxide removal deployment at such scales. Therefore, we cannot be confident that temperature decline after overshoot is achievable within the timescales expected today. Only rapid near-term emission reductions are effective in reducing climate risks.
本文链接：《自然》（20241010出版）一周论文导读http://www.llsum.com/show-11-12341-0.html
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