米兰-《科学》（20241004出版）一周论文导读—新闻—科学网

Science, 4 OCT 2024, VOL 386, ISSUE 6717

《科学》，2024年10月4日，第386卷，6717期

天文学Astronomy

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

不雅测全球日冕磁场在8个月内的演化

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

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

▲摘要：日冕中的磁场贮存着能量，这些能量可被释放出来加热等离子体并驱动太阳爆发。对全球日冕磁场的丈量仅限在几回快照。

在这项工作中，研究组利用进级版日冕多通道偏振仪进行不雅测，供给了跨度为8个月的太阳翼上方全球日冕的114张磁场图。终究肯定了日冕磁场随高度的散布，并监测了屡次太阳自转进程中分歧纬度的演化。

1.05~1.60太阳半径规模内的场强转变幅度为 1高斯至约20高斯。日冕磁场丈量中也呈现了活跃经度特点。日冕模子整体上与该不雅测成果一致，虽然在高纬度地域存在较年夜差别。

▲ 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.

材料科学Materials Science

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

纳米晶材猜中的晶粒扭转机制：铂薄膜的多标准不雅测

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

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

▲摘要：在纳米晶材料的晶粒发展、再结晶和塑性变形进程中，常常会不雅察到近刚体晶粒扭转。虽然颠末了数十年的研究，晶粒扭转的首要机制依然是个谜。

研究组供给了直接证据，注解在铂薄膜中，晶粒扭转经由过程沿晶界的断续活动（具有阶梯和位错特点的线缺点）产生。最早进的原位四维扫描透射电子显微镜（4D-STEM）不雅测揭露了晶粒扭转与晶粒发展或缩短之间的统计相干性。

这类相干性源在经由过程断续活动产生的剪切耦合晶界迁徙，与原位高角度环形暗场STEM不雅测和原子摹拟辅助阐发所证实的一致。该发现为纳米晶材料的布局动力学供给了定量看法。

▲ 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.

化学Chemistry

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

手性氢原子提取催化剂助力内消旋二醇对映选择性差向异构化

▲ 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.

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

▲摘要：氢原子提取是一个主要的根本化学进程，但很难对映选择性地进行。

研究组开辟了较易从金鸡纳生物碱家族自然产品中提取的催化剂，凭仗其手性胺布局可实现这一方针。该催化剂在单电子氧化后，经由过程选择性地从一个碳中间提取一个氢原子，以后再从硫醇中提取来从头取得一个氢原子，使内消旋二醇脱对称。这致使一个对映选择性差向异构化进程，构成具有高对映体过量的手性非对映体。

环状和非环状的1,2-二醇是相容的，非环状的1,3-二醇亦是如斯。研究组还证实了将该方式与Giese加成中的碳-碳键构成相连系的可行性。鉴在触及氢原子转移步调的合成方式愈来愈多，预期该工作将在对映选择性自由基化学范畴发生普遍的影响。

▲ 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

光催化呋喃转化为吡咯

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

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

▲摘要：芬芳环内杂原子的性质影响该杂环化合物的化学性质。但是，因为原子互换进程中的热力学掉配，系统地评估单个原子的影响带来了合成挑战。

研究组提出了一种光催化策略，将呋喃的氧原子与氮基团互换，在单个份子间反映中将呋喃直接转化为吡咯近似物。

成果不雅测到与药物发现中经常使用的各类呋喃衍生物和氮亲核试剂具有很高的相容性，而且后期官能化成功制备了从自然存在的高份子复杂性呋喃中难以取得的吡咯。机理阐发注解，经由过程单电子转移的极性反转激发了室温下氧化还原—中性原子互换进程。

▲ 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.

地球科学Earth Science

ENSO affects the North Atlantic Oscillation 1 year later

ENSO在1年后影响北年夜西洋涛动

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

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

▲ 摘要：研究组在不雅测阐发和蔼候模子中证实了厄尔尼诺—南边涛动（ENSO）的1年滞后温带响应。这类响应映照到北极涛动，在北年夜西洋最为强烈，与北年夜西洋涛动（NAO）类似。

出乎料想的是，这些滞后1年的遥相干最少与尽人皆知的冬季同步相干一样强。但是，滞后1年的响应在迹象上与同期响应相反，即1年后，厄尔尼诺现象以后是一个正相NAO，而拉尼娜现象以后是一个负相NAO。滞后响应也可能干扰同时产生的ENSO遥相干。

研究组注解，这些影响不太可能由ENSO轮回的残存混叠引发；相反，迟缓移动的年夜气角动量异常注释了温带响应的迹象和时候。该研究成果对理解ENSO遥相干、注释不雅测到的温带天气变率和注释季候到年际天气猜测具有主要意义。

▲ 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.

医学Medicine

Cancer immunotherapy by γδ T cells

γδ T细胞助力肿瘤免疫医治

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

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

▲摘要：癌症免疫疗法的条件是健康自我耐受的免疫系统可较着辨认癌症。癌症免疫医治的前景是免疫效应机制和免疫记忆可配合肃除癌症和没法手术的转移，并事实上接种预防复发的疫苗。对一些转移性黑色素瘤等迄今没法治愈的疾病，这一但愿正在经由过程基在αβT细胞改变游戏法则的免疫疗法来实现。

今天的挑战是针对更多癌症类型使更多分歧种族的患者受益，并在削减不良事务的同时实现治愈。在应对这些挑战时，γδT细胞有望供给特定的好处，它组成了第二种T细胞谱系，具有怪异的辨认能力和功能特点，可毗连先天免疫和顺应性免疫。

基在包罗现成过继细胞疗法和冲动剂抗体的γδT细胞临床实验，人们正在发生有但愿的成果，虽然依然存在可辨认的问题。在解决这些问题时，研究组主张免疫疗法以γδT细胞的怪异生物学为指点，这与正在进行的研究所说明的一致。

▲ Abstract：

The premise of cancer immunotherapy is that cancers are specifically visible to an immune system tolerized to healthy self. The promise of cancer immunotherapy is that immune effector mechanisms and immunological memory can jointly eradicate cancers and inoperable metastases and de facto vaccinate against recurrence. For some patients with hitherto incurable diseases, including metastatic melanoma, this promise is being realized by game-changing immunotherapies based on αβ T cells. Today’s challenges are to bring benefit to greater numbers of patients of diverse ethnicities, target more cancer types, and achieve a cure while incurring fewer adverse events. In meeting those challenges, specific benefits may be offered by γδ T cells, which compose a second T cell lineage with distinct recognition capabilities and functional traits that bridge innate and adaptive immunity. γδ T cell–based clinical trials, including off-the-shelf adoptive cell therapy and agonist antibodies, are yielding promising results, although identifiable problems remain. In addressing those problems, we advocate that immunotherapies be guided by the distinctive biology of γδ T cells, as elucidated by ongoing research.

特殊声明：本文转载仅仅是出在传布信息的需要，其实不意味着代表本网站不雅点或证实其内容的真实性；如其他媒体、网站或小我从本网站转载利用，须保存本网站注明的“来历”，并自大版权等法令责任；作者假如不但愿被转载或联系转载稿费等事宜，请与我们联系。