米兰-《自然》（20241010出版）一周论文导读—新闻—科学网

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，我们陈述器具有颀长C-C单键的烃的单电子氧化法分手碳原子间单电子σ键的化合物。经由过程单晶x射线衍射阐发和拉曼光谱阐发证实了100 K时C-C单电子σ键（2.921(3)?）的存在，并经由过程密度泛函理论计较证实了该键的存在。

本文的成果明白地证实了近一个世纪前假定的C-C单电子σ键的存在，从而可以期望经由过程摸索成键和非成键状况之间的鸿沟，为进一步成长化学的分歧范畴摊平道路。

▲ 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

▲摘要：

在此，我们公然了一种将脂肪族氨基酸转化为布局多样的近似物的慢慢脱氢方式。该方式成功的要害在在开辟了一种由光化学照耀驱动的选择性催化无受体脱氢方式，为下流功能化供给了结尾烯烃中心体的路子。

总的来讲，这类策略可以或许快速合成新的氨基酸构建块，并为后期润色更复杂的寡肽供给了可能性。

▲ 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.

Using both faces of polar semiconductor wafers for functional devices

利用极性半导体晶圆的两面用在功能器件

▲摘要：

在这项研究中，我们引入了双电子学，注解在统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。

这带来了在单一布局中操纵极性半导体的两面的可能性，此中电子、光子和声学特征可以在统一晶圆的相对面上实现，显著加强了这类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.

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况

▲摘要：

在此，我们开辟并利用一系列多量子位里德堡门来生成Greenberger–Horne–Zeilinger（GHZ）类型的薛定谔猫状况，在可编程原子阵列中具有多达9个光时钟量子位。在足够短的暗中时候下的原子激光比力中，我们利用最多四个量子比特的GHZ状况证实了低在尺度量子极限（SQL）的分数频率不不变性。

但是，因为它们的动态规模变小，单一尺寸的GHZ态与未纠缠的原子比拟在最好暗时没法提高可实现的时钟精度。为了降服这一障碍，我们同时预备了一个分歧巨细的GHZ状况级联，以便在耽误的距离内进行无歧义的相位估量。这些成果展现了接近海森堡有限标准的光学原子钟精度的要害构成部门。

▲ 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.

Permafrost slows Arctic riverbank erosion

永远冻土减缓了北极河岸的腐蚀

▲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，我们开辟了新的计较方式，可以在比卫星图象像素尺寸小5—10倍的长度标准上检测河岸腐蚀环境。这一立异使得在河道履历水暖和流量最年夜转变的次月时候标准上量化腐蚀酿成可能。

我们利用这些高频不雅测来束缚河岸腐蚀在多年夜水平上遭到热前提限制的水平——这一要求将在永远冻土熔化时消逝——并与有足够水流以运输组成河岸的沉积物的力学前提进行对照，后者是所有河道城市履历的环境。对阿拉斯加科尤库克河高分辩率数据的阐发注解，永远冻土的存在使腐蚀率下降了47%。

经由过程我们的不雅测，我们校准并验证了一个可以利用在分歧北极河道的数值模子。该模子猜测，永远冻土完全熔化可能致使北极河道的迁徙率增添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.

▲作者：Carl-Friedrich Schleussner, Gaurav Ganti et al.

▲链接：

https://www.nature.com/articles/s41586-024-08020-9

▲摘要：

在此，我们展现全球和区域天气转变和其相干风险在过冲后与避免过冲后的世界是分歧的。

我们发现，与仅不变全球变暖趋向比拟，实现全球气温降落可以限制持久天气风险，包罗海平面上升和冰冻圈转变。但是，全球变暖在将来几十年逆转的可能性可能与今天的顺应计划相干性有限。强烈的地球系统反馈可能会减弱温度逆转，致使近期和持久延续变暖。

为了对冲和庇护高风险后果，我们肯定了地球物理对几千亿吨的预防性二氧化碳断根能力的需求。但是，手艺、经济和可延续性方面的斟酌可能会限制实现这类范围的去除二氧化碳的摆设。是以，我们不克不及确信过冲后的温度降落在今天预期的时候标准内是可实现的。只有快速的短时间减排才能有用下降天气风险。

▲ 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.