《科学》（20210827出版）一周论文导读

编译 | 未玖

Science, 27 AUGUST 2021, VOL 373, ISSUE 6558

《科学》2021年8月27日，第373卷，6558期

材料科学Materials Science

Field-induced transition within the superconducting state of CeRh2As2

CeRh2As2超导态的场致跃迁

▲ 作者：S. Khim, J. F. Landaeta, J. Banda, N. Bannor, M. Brando, P. M. R. Brydon, et al.

▲ 链接：

https://science.sciencemag.org/content/373/6558/1012

▲ 摘要

具有多个超导相的材料很罕见。研究组报道了在CeRh2As2中发现的双相非常规超导电性。

使用热力学探针，研究组确定其高场相的超导临界场高达14 T，即使转变温度仅为0.26 K。此外，在c轴磁场中观察到两个不同超导相之间的转变。

铈位的局部反演对称破缺使得铈亚层之间交替发生拉什巴自旋轨道耦合。交错拉什巴耦合引入了一层自由度，实验中观察到的场致跃迁和高临界场可能与之相关。

▲ Abstract

Materials with multiple superconducting phases are rare. Here, we report the discovery of two-phase unconventional superconductivity in CeRh2As2. Using thermodynamic probes, we establish that the superconducting critical field of its high-field phase is as high as 14 tesla, even though the transition temperature is only 0.26 kelvin. Furthermore, a transition between two different superconducting phases is observed in a c axis magnetic field. Local inversion-symmetry breaking at the cerium sites enables Rashba spin-orbit coupling alternating between the cerium sublayers. The staggered Rashba coupling introduces a layer degree of freedom to which the field-induced transition and high critical field seen in experiment are likely related.

Highly conductive and elastic nanomembrane for skin electronics

高导电性弹性纳米膜电子皮肤

▲ 作者：Dongjun Jung, Chaehong Lim, Hyung Joon Shim, Yeongjun Kim, Chansul Park, Jaebong Jung, et al.

▲ 链接：

https://science.sciencemag.org/content/373/6558/1022

▲ 摘要

皮肤电子设备需要具有金属导电性、高延展性、超薄厚度和易模压性的可延展导体，但同时实现这些特性的难度相当大。

研究组提出了一种浮动组装方法来制备满足所有这些需求的纳米膜。该方法使纳米材料能够在水-油界面上紧密组装，并将其部分嵌入到超薄弹性膜中，可将施加的应变分散在弹性膜中，从而使纳米材料即便在高负载情况下也具有高弹性。

此外，该结构允许冷焊和双层堆叠，从而产生高导电性。这些特性即使在使用光刻技术制作高分辨率图案后仍能保持。利用图案化纳米膜可制备多功能表皮传感器阵列。

▲ Abstract

Skin electronics require stretchable conductors that satisfy metallike conductivity, high stretchability, ultrathin thickness, and facile patternability, but achieving these characteristics simultaneously is challenging. We present a float assembly method to fabricate a nanomembrane that meets all these requirements. The method enables a compact assembly of nanomaterials at the water–oil interface and their partial embedment in an ultrathin elastomer membrane, which can distribute the applied strain in the elastomer membrane and thus lead to a high elasticity even with the high loading of the nanomaterials. Furthermore, the structure allows cold welding and bilayer stacking, resulting in high conductivity. These properties are preserved even after high-resolution patterning by using photolithography. A multifunctional epidermal sensor array can be fabricated with the patterned nanomembranes.

化学Chemistry

Photomediated ring contraction of saturated heterocycles

光介导的饱和杂环缩环反应

▲ 作者：Justin Jurczyk, Michaelyn C. Lux, Donovon Adpressa, Sojung F. Kim, Yu-hong Lam,Charles S. Yeung, et al.

▲ 链接：

https://science.sciencemag.org/content/373/6558/1004

▲ 摘要

饱和杂环化合物存在于许多治疗药物和生物活性天然产物中，并且在许多药用和农用化合物库中也大量存在。人们对这些结构外围进行功能化，以获得新的化学空间功能。但目前很少有方法能够重构其核心框架。

研究组描述了可见光介导的α-酰化饱和杂环的缩环反应。这种非常规的转变与常规的环收缩正交，挑战了杂环化合物多样化的范式，包括哌啶、吗啉、噻烷、四氢吡喃和四氢异喹啉衍生物。

这种Norrish II型变体的成功取决于特定化学环境中光活性酮基团之间的反应性差异。该策略可应用于药物衍生物、多肽和糖的后期重塑。

▲ Abstract

Saturated heterocycles are found in numerous therapeutics and bioactive natural products and are abundant in many medicinal and agrochemical compound libraries. To access new chemical space and function, many methods for functionalization on the periphery of these structures have been developed. Comparatively fewer methods are known for restructuring their core framework. Herein, we describe a visible light–mediated ring contraction of α-acylated saturated heterocycles. This unconventional transformation is orthogonal to traditional ring contractions, challenging the paradigm for diversification of heterocycles including piperidine, morpholine, thiane, tetrahydropyran, and tetrahydroisoquinoline derivatives. The success of this Norrish type II variant rests on reactivity differences between photoreactive ketone groups in specific chemical environments. This strategy was applied to late-stage remodeling of pharmaceutical derivatives, peptides, and sugars.

Low thermal conductivity in a modular inorganic material with bonding anisotropy and mismatch

键各向异性和错配的低导热率模块化无机材料

▲ 作者：Quinn D. Gibson, Tianqi Zhao, Luke M. Daniels, Helen C. Walker, Ramzy Daou, Sylvie Hébert, et al.

▲ 链接：

https://science.sciencemag.org/content/373/6558/1017

▲ 摘要

晶体材料的导热率不能任意低，因为固有极限取决于声子色散。

研究组使用互补策略来抑制纵向和横向声子对含有不同类型固有化学界面的层状材料热传输的贡献。

BiOCl和Bi2O2Se分别封装了纵向模型和横向模型的设计原则，而体块超晶格材料Bi4O4SeCl2将两者结合，通过在其单位晶胞内排列两种界面类型，在室温下沿其堆叠方向达到低至0.1 W·K-1·m-1的导热率。该数值小于空气导热率的四分之一。

研究组证明了化学控制不同界面的空间排列可协同调控振动模式以最小化导热率。

▲ Abstract

The thermal conductivity of crystalline materials cannot be arbitrarily low, as the intrinsic limit depends on the phonon dispersion. We used complementary strategies to suppress the contribution of the longitudinal and transverse phonons to heat transport in layered materials that contain different types of intrinsic chemical interfaces. BiOCl and Bi2O2Se encapsulate these design principles for longitudinal and transverse modes, respectively, and the bulk superlattice material Bi4O4SeCl2 combines these effects by ordering both interface types within its unit cell to reach an extremely low thermal conductivity of 0.1 watts per kelvin per meter at room temperature along its stacking direction. This value comes within a factor of four of the thermal conductivity of air. We demonstrated that chemical control of the spatial arrangement of distinct interfaces can synergically modify vibrational modes to minimize thermal conductivity.

地球科学Earth Science

A positive relationship between functional redundancy and temperature in Cenozoic marine ecosystems

新生代海洋生态系统中功能冗余度与温度正相关

▲ 作者：T. M. Womack, J. S. Crampton, M. J. Hannah, K. S. Collins

▲ 链接：

https://science.sciencemag.org/content/373/6558/1027

▲ 摘要

气候变化对生物多样性和生物地理格局的长期影响尚不确定。已知地理区域与物种数量和生态功能群数量的关系分别称为物种-区域关系和功能多样性-区域关系。

研究组表明，新西兰浅海化石记录中，在约4000万年的时间跨度内，一个地区的物种数量、生态功能群数量和海洋温度之间存在正相关关系。这种关系的一个含义是，功能冗余度随着温度的升高而增加。

这揭示了生物多样性的空间结构、功能冗余的温度依赖性和中纬度浅海生物多样性之间的长期持久关联。

▲ Abstract

The long-term effects of climate change on biodiversity and biogeographic patterns are uncertain. There are known relationships between geographic area and both the number of species and the number of ecological functional groups—termed the species-area relationship and the functional diversity–area relationship, respectively. We show that there is a positive relationship between the number of species in an area, the number of ecological functional groups, and oceanic temperature in the shallow-marine fossil record of New Zealand over a time span of ~40 million years. One implication of this relationship is that functional redundancy increases with temperature. This reveals a long-lived and persistent association between the spatial structuring of biodiversity, the temperature-dependence of functional redundancy, and shallow-marine biodiversity in mid-latitudes.

Insolation triggered abrupt weakening of Atlantic circulation at the end of interglacials

间冰期结束时，太阳辐射导致大西洋环流突然减弱

▲ 作者：Q. Z. Yin, Z. P. Wu, A. Berger, H. Goosse, D. Hodell

▲ 链接：

https://science.sciencemag.org/content/373/6558/1035

▲ 摘要

在许多古气候记录中，间冰期结束时可观察到突然变冷，但其机制尚不清楚。

利用模型模拟，研究组证明了天文日照水平存在一个阈值，低于该阈值，在过去80万年的间冰期结束时就会发生气候突变。

当日照减少达到临界值时，会引发大西洋经向翻转环流的强烈突变减弱，并伴随着持续数千年高振幅变化的较冷的平均气候状态。

该机制涉及北欧和拉布拉多海的海冰反馈。该阈值的普遍性表明，它在间冰期结束时终止温暖气候条件方面起着根本作用。

▲ Abstract

Abrupt cooling is observed at the end of interglacials in many paleoclimate records, but the mechanism responsible remains unclear. Using model simulations, we demonstrate that there exists a threshold in the level of astronomically induced insolation below which abrupt changes at the end of interglacials of the past 800,000 years occur. When decreasing insolation reaches the critical value, it triggers a strong, abrupt weakening of the Atlantic meridional overturning circulation and a cooler mean climate state accompanied by high-amplitude variations lasting for several thousand years. The mechanism involves sea ice feedbacks in the Nordic and Labrador Seas. The ubiquity of this threshold suggests its fundamental role in terminating the warm climate conditions at the end of interglacials.