作者:李言 来源:科学网微信公众号 发布时间:2023/11/25 21:03:20
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《自然》(20231123出版)一周论文导读

 

 编译 | 李言

Nature,  23 November 2023, Volume 623 Issue 7988

《自然》, 2023年11月23日,第623卷,7988期

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天文学Astronomy 

Aligned grains and scattered light found in gaps of planet-forming disk

在行星形成盘的间隙中发现对齐颗粒和散射光

▲ 作者:Ian W. Stephens, Zhe-Yu Daniel Lin et al.

▲ 链接:

https://www.nature.com/articles/s41586-023-06648-7

▲ 摘要:

在此,我们展示了HL Tau在870μm的高分辨率深度极化观测,解决了环和间隙中的极化现象。我们发现,间隙的偏振角与环相比具有显著的方位角分量和更高的极化分数。我们的模型表明,圆盘极化是由排列的有效延长的对齐颗粒散射和辐射引起的。

这些对齐颗粒的本征极化率可能超过10%,远高于低分辨率观测的预期值(约1%)。在非偏振观测中难以观测到的不对称性和尘埃特征在极化观测中可以看到。

▲ Abstract:

Here we show deep, high-resolution polarization observations of HL Tau at 870??μm, resolving polarization in both the rings and the gaps. We find that the gaps have polarization angles with a notable azimuthal component and a higher polarization fraction than the rings. Our models show that the disk polarization is due to both scattering and emission from the aligned effectively prolate grains. The intrinsic polarization of aligned dust grains is probably more than 10%, which is much higher than that expected in low-resolution observations (about 1%). Asymmetries and dust features that are not seen in non-polarimetric observations are seen in the polarization observations.

Methane throughout the atmosphere of the warm exoplanet WASP-80b

温暖的系外行星WASP-80b的大气中都是甲烷

▲ 作者:Taylor J. Bell, Luis Welbanks et al.

▲ 链接:

https://www.nature.com/articles/s41586-023-06687-0

▲ 摘要:

在此,我们报告了JWST的NIRCam成像仪对825 K的温暖木星WASP-80b的观测结果。我们观察到透射和发射光谱跨度为2.4–4.0μm,强有力地证明了甲烷的存在,且显著性大于6σ。

从两种观测几何形状中得到的甲烷丰度彼此一致,与太阳到亚太阳的碳氢比一致,约为太阳金属丰度的5倍,与理论预测一致。

▲ Abstract:

Here we report transmission and emission spectra spanning 2.4–4.0 μm of the 825 K warm Jupiter WASP-80b taken with the NIRCam instrument of the JWST, both of which show strong evidence of CH4 at greater than 6σ significance. The derived CH4 abundances from both viewing geometries are consistent with each other and with solar to sub-solar C/O and around five times solar metallicity, which is consistent with theoretical predictions.

物理学Physics 

Continuous symmetry breaking in a trapped-ion spin chain

陷俘离子自旋链中的连续对称破缺

▲ 作者:Lei Feng, Or Katz et al.

▲ 链接:

https://www.nature.com/articles/s41586-023-06656-7

▲ 摘要:

在此,我们使用一维陷俘离子量子模拟器制备了具有长程自旋序的状态,该状态扩展到23个自旋的系统,并且展示物质连续对称破缺相的特征。我们的准备工作包括同时控制一组紧密聚焦的单个寻址激光束,用于产生远距离自旋—自旋相互作用。

我们还观察到一个具有阻挫关联性的无序相。我们进一步研究了在不同相互作用范围内相的存在,以及对称破缺扰动下的非平衡响应。这项研究为研究低维系统中的新量子相和非平衡动力学开辟了新途径。

▲ Abstract:

Here we use a one-dimensional trapped-ion quantum simulator to prepare states with long-range spin order that extends over the system size of up to 23 spins and is characteristic of the continuous symmetry-breaking phase of matter. Our preparation relies on simultaneous control over an array of tightly focused individual addressing laser beams, generating long-range spin–spin interactions. We also observe a disordered phase with frustrated correlations. We further study the phases at different ranges of interaction and the out-of-equilibrium response to symmetry-breaking perturbations. This work opens an avenue to study new quantum phases and out-of-equilibrium dynamics in low-dimensional systems.

Hopfion rings in a cubic chiral magnet

在一个立方手性磁体中的霍普夫子环

▲ 作者:Fengshan Zheng, Nikolai S. Kiselev et al.

▲ 链接:

https://www.nature.com/articles/s41586-023-06658-5

▲ 摘要:

在此,我们对晶体中霍普夫子进行了直接观察。在我们的实验中,我们使用透射电子显微镜观察了B20型FeGe板中霍普夫子与斯格明子弦形成耦合态的过程。我们提供了一个霍普夫子成核的协议,并采用洛伦兹成像和电子全息技术进行验证。

我们的结果具有很高的可重复性,与微磁模拟完全一致。我们还提供了一个统一的斯格明子-霍普夫子同伦分类方法,为对理解三维手性磁体中拓扑孤子多样性提供了见解。

▲ Abstract:

Here we present direct observations of hopfions in crystals. In our experiment, we use transmission electron microscopy to observe hopfions forming coupled states with skyrmion strings in B20-type FeGe plates. We provide a protocol for nucleating such hopfion rings, which we verify using Lorentz imaging and electron holography. Our results are highly reproducible and in full agreement with micromagnetic simulations. We provide a unified skyrmion–hopfion homotopy classification and offer insight into the diversity of topological solitons in three-dimensional chiral magnets.

化学Chemistry

Complex molecule synthesis by electrocatalytic decarboxylative cross-coupling

电催化脱羧偶联合成复杂分子

▲ 作者:Benxiang Zhang, Jiayan He et al.

▲ 链接:

https://www.nature.com/articles/s41586-023-06677-2

▲ 摘要:

在此,我们报道了一种基于自由基的Ni/Ag电催化取代羧酸的交叉偶联反应,从而实现了用一种直观和模块化的方法来构建复杂的分子结构。这种新方法依赖于一种关键的银添加剂,这种添加剂可以在原位形成活性银纳米颗粒涂层的电极表面,以及精心选择的调节镍反应活性的配体。

通过合理选择条件和配体,交叉偶联可以具有高度的非对映选择性。为了证明这些反应的简化能力,我们实现了14种天然产物和两种药物相关分子的简洁合成。

▲ Abstract:

Here we report a radical-based Ni/Ag-electrocatalytic cross-coupling of substituted carboxylic acids, thereby enabling an intuitive and modular approach to accessing complex molecular architectures. This new method relies on a key silver additive that forms an active Ag nanoparticle-coated electrode surface in situ along with carefully chosen ligands that modulate the reactivity of Ni. Through judicious choice of conditions and ligands, the cross-couplings can be rendered highly diastereoselective. To demonstrate the simplifying power of these reactions, concise syntheses of 14 natural products and two medicinally relevant molecules were completed.

生物学Biology

Preserved neural dynamics across animals performing similar behaviour

表现相似行为的动物之间保持的神经动力学

▲ 作者:Mostafa Safaie, Joanna C. Chang et al.

▲ 链接:

https://www.nature.com/articles/s41586-023-06714-0

▲ 摘要:

我们认为物种内共享的神经回路水平约束将导致个体间适当保留潜在动力学。我们分析了来自猴子和老鼠运动皮层的神经群记录,以证明来自同一物种的个体在表现相似行为时,其神经动力学惊人地保留了下来。

当动物有意识地计划未来的运动而不表现出明显的行为,并能够解码不同个体之间计划和正在进行的运动时,神经种群动力学也得以保留。

此外,我们发现保存的神经动力学从皮质区域延伸到背纹状体,这是一个演化上更古老的结构。最后,我们使用神经网络模型来证明行为相似性对于这种保存是必要的,但不是充分的。我们假设这些涌现的动态源于大脑发育的演化约束,因此反映了行为的神经基础的基本特性。

▲ Abstract:

Accordingly, here we suggested that the shared circuit-level constraints within a species would lead to suitably preserved latent dynamics across individuals. We analysed recordings of neural populations from monkey and mouse motor cortex to demonstrate that neural dynamics in individuals from the same species are surprisingly preserved when they perform similar behaviour. Neural population dynamics were also preserved when animals consciously planned future movements without overt behaviour and enabled the decoding of planned and ongoing movement across different individuals. Furthermore, we found that preserved neural dynamics extend beyond cortical regions to the dorsal striatum, an evolutionarily older structure. Finally, we used neural network models to demonstrate that behavioural similarity is necessary but not sufficient for this preservation. We posit that these emergent dynamics result from evolutionary constraints on brain development and thus reflect fundamental properties of the neural basis of behaviour.

 
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