《科学》(20240607)一周论文导读

编译｜冯维维

Science, 7 Jun 2024, Volume 384, Issue 6700,

《科学》2024年6月7日，第384卷，6700期

物理学Physics

Abundant hydrocarbons in the disk around a very-low-mass star

一颗低质量恒星周围的星系盘上有丰富的碳氢化合物

▲ 作者：A. M. ARABHAVI, I. KAMP, TH. HENNING, E. F. VAN DISHOECK, V. CHRISTIAENS, D. GASMAN, A. PERRIN, M. GÜDEL, B. TABONE, AND G. ÖSTLIN

▲ 链接：

https://www.science.org/doi/10.1126/science.adi8147

▲ 摘要：

在大多数天体中，碳和氧的丰度相似。然而，在冷到足以形成分子的区域，根据它们的相对丰度，最终的化学反应可能富含碳或氧。

研究者利用中红外光谱研究了一颗年轻的低质量恒星周围的原行星盘，发现其光谱以小碳氢化合物分子为主，这表明盘内气体的碳氧比很高。他们讨论了产生这种碳富集的可能机制，并提出它可能影响盘内形成的任何行星的组成。

▲ Abstract：

In most astronomical objects, carbon and oxygen have similar abundances. However, in regions cool enough for molecules to form, the resulting chemistry can be carbon or oxygen rich depending on their relative abundances. Arabhavi et al. used midinfrared spectroscopy to investigate the PRotoplanetary disk around a YOUng low-mass star, finding that its spectrum is dominated by small hydrocarbon molecules, which indicates a high carbon/oxygen ratio in the inner disk gas. The authors discuss possible mechanisms to produce this carbon enrichment and suggest that it could influence the composition of any planets that form within the disk.

Localized thermal emission from topological interfaces

拓扑界面的局域热发射

▲ 作者：M. SAID ERGOKTAS, ALI KECEBAS, KONSTANTINOS DESPOTELIS, SINA SOLEYMANI, GOKHAN BAKAN, ASKIN KOCABAS, ALESSANDRO PRINCIPI, STEFAN ROTTER, SAHIN K. OZDEMIR, AND COSKUN KOCABAS

▲ 链接：

https://www.science.org/doi/10.1126/science.ado0534

▲ 摘要：

通过塑造热辐射的空间和光谱发射特性来控制热辐射在许多科学和工程领域中起着关键作用。利用超材料剪裁热发射的传统方法受到所需亚波长材料结构的有限空间分辨率和材料在红外中的强吸收的阻碍。

研究者展示了一种基于拓扑概念的方法。通过改变多层涂层的单个参数，他们能够控制表面的反射拓扑结构，并且零反射的临界点受到拓扑保护。亚临界和超临界空间域之间的边界具有接近统一热辐射率的拓扑界面态。这些拓扑概念使热光在热管理和热伪装应用中的非常规操作成为可能。

▲ Abstract：

The control of thermal radiation by shaping its spatial and spectral emission characteristics plays a key role in many areas of science and engineering. Conventional approaches to tailoring thermal emission using metamaterials are hampered both by the limited spatial resolution of the required subwavelength material structures and by the materials’ strong absorption in the infrared. In this work, we demonstrate an approach based on the concept of topology. By changing a single parameter of a multilayer coating, we were able to control the reflection topology of a surface, with the critical point of zero reflection being topologically protected. The boundaries between subcritical and supercritical spatial domains host topological interface states with near-unity thermal emissivity. These topological concepts enable unconventional manipulation of thermal light for applications in thermal management and thermal camouflage.

Spontaneous chiral symmetry breaking in polar fluid–heliconical ferroelectric nematic phase

极性流体-螺旋铁电向列相的自发手性对称性破缺

▲ 作者：JAKUB KARCZ, JAKUB HERMAN, NATAN RYCHŁOWICZ, PRZEMYSŁAW KULA, EWA GÓRECKA, JADWIGA SZYDLOWSKA, PAWEL W. MAJEWSKI, AND DAMIAN POCIECHA

▲ 链接：

https://www.science.org/doi/10.1126/science.adn6812

▲ 摘要：

由非手性结构组成的自发镜像对称破缺和涌现的极性顺序是在流体中很少观察到的现象。它们分别存在于某些向列相液晶中；然而，它们从来没有同时被观察到过。研究者报告了铁电向列相中非手性分子的螺旋排列。因此相自然地同时具有极性和手性。

值得注意的是，螺旋结构的间距与可见光的波长相当，可以通过温度或弱电场的应用进行选择性反射。尽管与螺旋扭弯向列相相似，但这种手性铁电向列相是由电相互作用引起的电偶极子的非共线取向。

▲ Abstract：

Spontaneous mirror symmetry breaking by formation of chiral structures from achiral building blocks and emergent polar order are phenomena rarely observed in fluids. Separately, they have both been found in certain nematic liquid crystalline phases; however, they have never been observed simultaneously. Here, we report a heliconical arrangement of achiral molecules in the ferroelectric nematic phase. The phase is thus spontaneously both polar and chiral. Notably, the pitch of the heliconical structure is comparable to the wavelength of visible light, giving selective reflection controllable by temperature or application of a weak electric field. Despite bearing resemblance to the heliconical twist-bend nematic phase, this chiral ferroelectric nematic phase arises from electrical interactions that induce a noncollinear orientation of electric dipoles.

化学Chemistry

WS2 ribbon arrays with defined chirality and coherent polarity

具有明确的手性和相干极性的WS2带状阵列

▲ 作者：GUODONG XUE, ZIQI ZHOU, QUANLIN GUO, YONGGANG ZUO, WENYA WEI, JIASHU YANG, PENG YIN, SHUAI ZHANG, DING ZHONG, AND KAIHUI LIU

▲ 链接：

https://www.science.org/doi/10.1126/science.adn9476

▲ 摘要：

一维过渡金属二硫族化物表现出增强的体光伏效应，在p-n结结构中的太阳能收集中有超过Shockley-Queisser极限效率的潜力。然而，这些原型设备的集体输出仍然是一个挑战。研究者报道了通过原子制造策略合成具有明确手性和相干极性的单晶WS2带阵列。

WS2带的手性由底物耦合为可调扶手型、之型和手性三种类型来定义，极性方向由带—前驱体界面能沿相干方向决定。单个扶手椅带状显示出强大的体光伏效应，进一步集成约1000条具有相干极性的排列带状可以实现光电流的放大。

▲ Abstract：

One-dimensional transition metal dichalcogenides exhibiting an enhanced bulk photovoltaic effect have the potential to exceed the Shockley–Queisser limit efficiency in solar energy harvest within p-n junction architectures. However, the collective output of these prototype devices remains a challenge. We report on the synthesis of single-crystalline WS2 ribbon arrays with defined chirality and coherent polarity through an atomic manufacturing strategy. The chirality of WS2 ribbon was defined by substrate couplings into tunable armchair, zigzag, and chiral species, and the polarity direction was determined by the ribbon-precursor interfacial energy along a coherent direction. A single armchair ribbon showed strong bulk photovoltaic effect and the further integration of ~1000 aligned ribbons with coherent polarity enabled upscaling of the photocurrent.

生物学Biology

Axis formation in annual killifish: Nodal and β-catenin regulate morphogenesis without Huluwa prepatterning

一年生鳉鱼轴的形成

▲ 作者：PHILIP B. ABITUA, LAURA M. STUMP, DENIZ C. AKSEL, AND ALEXANDER F. SCHIER

▲ 链接：

https://www.science.org/doi/10.1126/science.ado7604

▲ 摘要：

一年生鳉鱼Nothobranchius furzeri的发育揭示了胚胎发生过程中一个迷人的转折。在其他鱼类中，母亲为卵提供产品以确定胚胎轴，但这些鳉鱼不遵循此原则。

研究者发现，在发育中的胚胎中，鳉鱼卵裂球细胞在没有母体决定因素（一种名为Huluwa的蛋白质）的指导下，沿着卵黄扩散、聚集并形成体轴。此外，鳉鱼重新利用了两个重要的信号通路Nodal和β-catenin来协调聚集和轴的形成。

这种发育策略可能有助于年生鳉鱼在干旱条件下生存，并且它与合成哺乳动物胚胎的自组织过程具有共同的特征。

▲ Abstract：

Development in the annual killifish, Nothobranchius furzeri, reveals a fascinating twist in the story of embryogenesis. In other fishes, mothers provide products to the egg to determine the embryonic axes, but these killifish do not follow this script. Abitua et al. discovered that killifish blastomere cells spread across the yolk, aggregate, and form a body axis in the developing embryo without the instruction of the maternal determinant, a protein named Huluwa. Moreover, killifish repurposed two important signaling pathways, Nodal and β-catenin, to coordinate aggregation and axis formation. This developmental strategy may help annual killifish survive drought conditions, and it shares features with the self-organization process of synthetic mammalian embryos.

Two-stage evolution of mammalian adipose tissue thermogenesis

哺乳动物脂肪组织产热的两阶段演化

▲ 作者：SUSANNE KEIPERT, MICHAEL J. GAUDRY, MARIA KUTSCHKE, MICHAELA KEUPER, MARGEOUX A. S. DELA ROSA, YIMING CHENG, JOSÉ M. MONROY KUHN, RUTGER LATERVEER, CAMILA A. COTRIM, AND MARTIN JASTROCH

▲ 链接：

https://www.science.org/doi/10.1126/science.adg1947

▲ 摘要：

褐色脂肪组织（BAT）是一种加热器官，表达产热解偶联蛋白1 （UCP1），在低温胁迫下维持高体温。BAT产热被认为是哺乳动物的主要特征，但其进化起源尚不清楚。

我们发现，大约1.5亿年前从真动物哺乳动物分化出来的有袋动物的脂肪组织表达一种非产热性的UCP1变体，这种变体由部分转录组BAT特征控制，与真动物米色脂肪组织中发现的相似。我们发现，重建的真兽祖先UCP1序列显示出典型的产热活性，而兽祖先UCP1则是非产热的。

因此，哺乳动物脂肪组织产热可能经历了两个不同的进化阶段，在兽类共同祖先的产热前阶段将UCP1表达与脂肪组织和热应激联系起来。研究者认为，在第二阶段，UCP1获得了其产热功能，特别是在真兽中，因此哺乳动物的BAT产热功能是在与有袋动物分化之后才开始的。

▲ Abstract：

Brown adipose tissue (BAT) is a heater organ that expresses thermogenic uncoupling protein 1 (UCP1) to maintain high body temperatures during cold stress. BAT thermogenesis is considered an overarching mammalian trait, but its evolutionary origin is unknown. We show that adipose tissue of marsupials, which diverged from eutherian mammals ~150 million years ago, expresses a nonthermogenic UCP1 variant governed by a partial transcriptomic BAT signature similar to that found in eutherian beige adipose tissue. We found that the reconstructed UCP1 sequence of the common eutherian ancestor displayed typical thermogenic activity, whereas therian ancestor UCP1 is nonthermogenic. Thus, mammalian adipose tissue thermogenesis may have evolved in two distinct stages, with a prethermogenic stage in the common therian ancestor linking UCP1 expression to adipose tissue and thermal stress. We propose that in a second stage, UCP1 acquired its thermogenic function specifically in eutherians, such that the onset of mammalian BAT thermogenesis occurred only after the divergence from marsupials.