《科學》（20241004出版）一周論文導讀

原文地址：http://news.sciencenet.cn/htmlnews/2024/10/531091.shtm

編譯|未玖

Science, 4 OCT 2024, VOL 386, ISSUE 6717

《科學》，2024年10月4日，第386卷，6717期

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天文學Astronomy

Observing the evolution of the Sun’s global coronal magnetic field over 8 months

觀測全球日冕磁場在8個月內的演變

▲ 作者：ZIHAO YANG, HUI TIAN, STEVEN TOMCZYK, XIANYU LIU, SARAH GIBSON, RICHARD J. MORTON, ET AL.

▲ 鏈接：https://www.science.org/doi/10.1126/science.ado2993

▲摘要：日冕中的磁場儲存著能量，這些能量可被釋放出來加熱等離子體并驅動太陽爆發。對全球日冕磁場的測量僅限于幾次快照。

在這項工作中，研究組使用升級版日冕多通道偏振儀進行觀測，提供了跨度為8個月的太陽翼上方全球日冕的114張磁場圖。最終確定了日冕磁場隨高度的分布，并監測了多次太陽自轉過程中不同緯度的演變。

1.05~1.60太陽半徑范圍內的場強變化幅度為<1高斯至約20高斯。日冕磁場測量中也出現了活躍經度特征。日冕模型總體上與該觀測結果一致，盡管在高緯度地區存在較大差異。

▲ Abstract：

The magnetic field in the Sun’s corona stores energy that can be released to heat plasma and drive solar eruptions. Measurements of the global coronal magnetic field have been limited to several snapshots. In this work, we present observations, using the Upgraded Coronal Multi-channel Polarimeter, that provide 114 magnetograms of the global corona above the solar limb spanning ~8 months. We determined the magnetic field distribution with altitude in the corona and monitored the evolution at different latitudes over multiple solar rotations. The field strength between 1.05 and 1.60 solar radii varies from <1 to ~20 gauss. A signature of active longitudes appears in the coronal magnetic field measurements. Coronal models are generally consistent with our observations, though they have larger discrepancies in high-latitude regions.

材料科學Materials Science

Grain rotation mechanisms in nanocrystalline materials: Multiscale observations in Pt thin films

納米晶材料中的晶粒旋轉機制：鉑薄膜的多尺度觀測

▲ 作者：YUAN TIAN, XIAOGUO GONG, MINGJIE XU, CAIHAO QIU, YING HAN, YUTONG BI, ET AL.

▲ 鏈接：https://www.science.org/doi/10.1126/science.adk6384

▲摘要：在納米晶材料的晶粒生長、再結晶和塑性變形過程中，經常會觀察到近剛體晶粒旋轉。盡管經過了數十年的研究，晶粒旋轉的主要機制仍然是個謎。

研究組提供了直接證據，表明在鉑薄膜中，晶粒旋轉通過沿晶界的斷續運動（具有階梯和位錯特征的線缺陷）發生。最先進的原位四維掃描透射電子顯微鏡（4D-STEM）觀測揭示了晶粒旋轉與晶粒生長或收縮之間的統計相關性。

這種相關性源于通過斷續運動發生的剪切耦合晶界遷移，與原位高角度環形暗場STEM觀測和原子模擬輔助分析所證明的一致。該發現為納米晶材料的結構動力學提供了定量見解。

▲ Abstract：

Near-rigid-body grain rotation is commonly observed during grain growth, recrystallization, and plastic deformation in nanocrystalline materials. Despite decades of research, the dominant mechanisms underlying grain rotation remain enigmatic. We present direct evidence that grain rotation occurs through the motion of disconnections (line defects with step and dislocation character) along grain boundaries in platinum thin films. State-of-the-art in situ four-dimensional scanning transmission electron microscopy (4D-STEM) observations reveal the statistical correlation between grain rotation and grain growth or shrinkage. This correlation arises from shear-coupled grain boundary migration, which occurs through the motion of disconnections, as demonstrated by in situ high-angle annular dark-field STEM observations and the atomistic simulation–aided analysis. These findings provide quantitative insights into the structural dynamics of nanocrystalline materials.

化學Chemistry

A chiral hydrogen atom abstraction catalyst for the enantioselective epimerization of meso-diols

手性氫原子提取催化劑助力內消旋二醇對映選擇性差向異構化

▲ 作者：ANTTI S. K. LAHDENPER?, JYOTI DHANKHAR, DANIEL J. DAVIES, NELSON Y. S. LAM, P. DAVID BACO?, KAREN DE LA VEGA-HERNáNDEZ, ET AL.

▲ 鏈接：https://www.science.org/doi/10.1126/science.adq8029

▲摘要：氫原子提取是一個重要的基礎化學過程，但很難對映選擇性地進行。

研究組開發了較易從金雞納生物堿家族天然產物中提取的催化劑，憑借其手性胺結構可實現這一目標。該催化劑在單電子氧化后，通過選擇性地從一個碳中心提取一個氫原子，之后再從硫醇中提取來重新獲得一個氫原子，使內消旋二醇脫對稱。這導致一個對映選擇性差向異構化過程，形成具有高對映體過量的手性非對映體。

環狀和非環狀的1,2-二醇是相容的，非環狀的1,3-二醇亦是如此。研究組還證明了將該方法與Giese加成中的碳-碳鍵形成相結合的可行性。鑒于涉及氫原子轉移步驟的合成方法越來越多，預期該工作將在對映選擇性自由基化學領域產生廣泛的影響。

▲ Abstract：

Hydrogen atom abstraction is an important elementary chemical process but is very difficult to carry out enantioselectively. We have developed catalysts, readily derived from the Cinchona alkaloid family of natural products, which can achieve this by virtue of their chiral amine structure. The catalyst, following single-electron oxidation, desymmetrizes meso-diols by selectively abstracting a hydrogen atom from one carbon center, which then regains a hydrogen atom by abstraction from a thiol. This results in an enantioselective epimerization process, forming the chiral diastereomer with high enantiomeric excess. Cyclic and acyclic 1,2-diols are compatible, as are acyclic 1,3-diols. Additionally, we demonstrate the viability of combining our approach with carbon-carbon bond formation in Giese addition. Given the increasing number of synthetic methods involving hydrogen atom transfer steps, we anticipate that this work will have a broad impact in the field of enantioselective radical chemistry.

Photocatalytic furan-to-pyrrole conversion

光催化呋喃轉化為吡咯

▲ 作者：DONGHYEON KIM, JAEHYUN YOU, DA HYE LEE, HOJIN HONG, DONGWOOK KIM AND YOONSU PARK

▲ 鏈接：https://www.science.org/doi/10.1126/science.adq6245

▲摘要：芳香環內雜原子的性質影響該雜環化合物的化學性質。然而，由于原子交換過程中的熱力學失配，系統地評估單個原子的影響帶來了合成挑戰。

研究組提出了一種光催化策略，將呋喃的氧原子與氮基團交換，在單個分子間反應中將呋喃直接轉化為吡咯類似物。

結果觀測到與藥物發現中常用的各種呋喃衍生物和氮親核試劑具有很高的相容性，并且后期官能化成功制備了從天然存在的高分子復雜性呋喃中難以獲得的吡咯。機理分析表明，通過單電子轉移的極性反轉引發了室溫下氧化還原—中性原子交換過程。

▲ Abstract：

The identity of a heteroatom within an aromatic ring influences the chemical properties of that heterocyclic compound. Systematically evaluating the effect of a single atom, however, poses synthetic challenges, primarily as a result of thermodynamic mismatches in atomic exchange processes. We present a photocatalytic strategy that swaps an oxygen atom of furan with a nitrogen group, directly converting the furan into a pyrrole analog in a single intermolecular reaction. High compatibility was observed with various furan derivatives and nitrogen nucleophiles commonly used in drug discovery, and the late-stage functionalization furnished otherwise difficult-to-access pyrroles from naturally occurring furans of high molecular complexity. Mechanistic analysis suggested that polarity inversion through single electron transfer initiates the redox-neutral atom exchange processes at room temperature.

地球科學Earth Science

ENSO affects the North Atlantic Oscillation 1 year later

ENSO在1年后影響北大西洋濤動

▲ 作者：ADAM A. SCAIFE, NICK DUNSTONE, STEVEN HARDIMAN, SARAH INESON, CHAOFAN LI, RIYU LU, ET AL.

▲ 鏈接：https://www.science.org/doi/10.1126/science.adk4671

▲ 摘要：研究組在觀測分析和氣候模型中證明了厄爾尼諾—南方濤動（ENSO）的1年滯后溫帶響應。這種響應映射到北極濤動，在北大西洋最為強烈，與北大西洋濤動（NAO）相似。

出乎意料的是，這些滯后1年的遙相關至少與眾所周知的冬季同步相關一樣強。然而，滯后1年的響應在跡象上與同期響應相反，即1年后，厄爾尼諾現象之后是一個正相NAO，而拉尼娜現象之后是一個負相NAO。滯后響應也可能干擾同時發生的ENSO遙相關。

研究組表明，這些影響不太可能由ENSO循環的殘余混疊引起；相反，緩慢移動的大氣角動量異常解釋了溫帶響應的跡象和時間。該研究結果對理解ENSO遙相關、解釋觀測到的溫帶氣候變率以及解釋季節到年際氣候預測具有重要意義。

▲ Abstract：

We demonstrate a 1-year lagged extratropical response to the El Ni?o–Southern Oscillation (ENSO) in observational analyses and climate models. The response maps onto the Arctic Oscillation and is strongest in the North Atlantic, where it resembles the North Atlantic Oscillation (NAO). Unexpectedly, these 1-year lagged teleconnections are at least as strong as the better-known simultaneous winter connections. However, the 1-year lagged response is opposite in sign to the simultaneous response such that 1 year later, El Ni?o is followed by a positive NAO, whereas La Ni?a is followed by a negative NAO. The lagged response may also interfere with simultaneous ENSO teleconnections. We show here that these effects are unlikely to be caused by residual aliasing of ENSO cycles; rather, slowly migrating atmospheric angular momentum anomalies explain both the sign and the timing of the extratropical response. Our results have implications for understanding ENSO teleconnections, explaining observed extratropical climate variability and interpreting seasonal to interannual climate predictions.

醫學Medicine

Cancer immunotherapy by γδ T cells

γδ T細胞助力腫瘤免疫治療

▲ 作者：ADRIAN HAYDAY, JULIE DECHANET-MERVILLE, JAMIE ROSSJOHN AND BRUNO SILVA-SANTOS

▲ 鏈接：https://www.science.org/doi/10.1126/science.abq7248

▲摘要：癌癥免疫療法的前提是健康自我耐受的免疫系統可明顯識別癌癥。癌癥免疫治療的前景是免疫效應機制和免疫記憶可共同根除癌癥和無法手術的轉移，并事實上接種預防復發的疫苗。對于一些轉移性黑色素瘤等迄今無法治愈的疾病，這一希望正在通過基于αβT細胞改變游戲規則的免疫療法來實現。

今天的挑戰是針對更多癌癥類型使更多不同種族的患者受益，并在減少不良事件的同時實現治愈。在應對這些挑戰時，γδT細胞有望提供特定的益處，它構成了第二種T細胞譜系，具有獨特的識別能力和功能特征，可連接先天免疫和適應性免疫。

基于包括現成過繼細胞療法和激動劑抗體的γδT細胞臨床試驗，人們正在產生有希望的結果，盡管仍然存在可識別的問題。在解決這些問題時，研究組主張免疫療法以γδT細胞的獨特生物學為指導，這與正在進行的研究所闡明的一致。

▲ Abstract：