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

《科学》2024年6月7日，第384卷，6700期

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物理学Physics

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

一颗低品质恒星周围的星系盘上有富厚的碳氢化合物

▲ 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. ?STLIN

▲ 链接：

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

▲ 择要：

于年夜大都天体中，碳以及氧的品貌相似。然而，于冷到足以造成份子的区域，按照它们的相对于品貌，终极的化学反映可能富含碳或者氧。

研究者哄骗中红外光谱研究了一颗年青的低品质恒星周围的原行星盘，发明其光谱以小碳氢化合物份子为主，这注解盘内气体的碳氧比很高。他们会商了孕育发生这类碳富集的可能机制，并提出它可能影响盘内造成的任何行星的构成。

▲ 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

▲ 择要：

经由过程塑造热辐射的空间以及光谱发射特征来节制热辐射于很多科学以及项目范畴中起着要害作用。哄骗超质料剪裁热发射的传统要领遭到所需亚波长质料布局的有限空间分辩率以及质料于红外中的强接收的拦阻。

研究者展示了一种基在拓扑观点的要领。经由过程转变多层涂层的单个参数，他们可以或许节制外貌的反射拓扑布局，而且零反射的临界点遭到拓扑掩护。亚临界以及超临界空间域之间的界限具备靠近同一热辐射率的拓扑界面态。这些拓扑观点使热光于热治理以及热假装运用中的很是规操作成为可能。

▲ 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 sy妹妹etry breaking in polar fluid–heliconical ferroelectric nematic phase

极性流体-螺旋铁电向列相的自觉手性对于称性破缺

▲ 作者：JAKUB KARCZ, JAKUB HERMAN, NATAN RYCH?OWICZ, PRZEMYS?AW KULA, EWA GóRECKA, JADWIGA SZYDLOWSKA, PAWEL W. MAJEWSKI, AND DAMIAN POCIECHA

▲ 链接：

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

▲ 择要：

由非手性布局构成的自觉镜像对于称破缺以及涌现的极性挨次是于流体中很少不雅察到的征象。它们别离存于在某些向列相液晶中；然而，它们从来没有同时被不雅察到过。研究者陈诉了铁电向列相中非手性份子的螺旋摆列。是以相天然地同时具备极性以及手性。

值患上留意的是，螺旋布局的间距与可见光的波长相称，可以经由过程温度或者弱电场的运用举行选择性反射。只管与螺旋扭弯向列相相似，但这类手性铁电向列相是由电彼此作用惹起的电偶极子的非共线取向。

▲ Abstract：

Spontaneous mirror sy妹妹etry 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

具备明确的手性以及相关极性的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

▲ 择要：

一维过渡金属二硫族化物体现出加强的体光伏效应，于p-n结布局中的太阳能网络中有跨越Shockley-Queisser极限效率的潜力。然而，这些原型装备的团体输出仍旧是一个应战。研究者报导了经由过程原子打造计谋合成具备明确手性以及相关极性的单晶WS2带阵列。

WS2带的手性由底物耦合为可调扶手型、之型以及手性三品种型来界说，极性标的目的由带—先驱体界面能沿相关标的目的决议。单个扶手椅带状显示出强盛的体光伏效应，进一步集成约1000条具备相关极性的摆列带状可以实现光电流的放年夜。

▲ 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 WS2ribbon 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

一年生鳉鱼轴的造成

▲ 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

▲ 择要：

一年生鳉鱼N���othobranchius furzeri的发育展现了胚胎发生历程中一个诱人的迁移转变。于其他鱼类中，母亲为卵提供产物以确定胚胎轴，但这些鳉鱼不遵照此准则。

研究者发明，于发育中的胚胎中，鳉鱼卵裂球细胞于没有母体决议要素（一种名为Huluwa的卵白质）的引导下，沿着卵黄散布、堆积并造成体轴。此外，鳉鱼从头哄骗了两个主要的旌旗灯号通路Nodal以及β-catenin来协调堆积以及轴的造成。

这类发育计谋可能有助在年生鳉鱼于干旱前提下保存，而且它与合成哺乳植物胚胎的自构造历程具备配合的特性。

▲ 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 ma妹妹alian embryos.

Two-stage evolution of ma妹妹alian adipose tissue thermogenesis

哺乳植物脂肪构造产热的两阶段演化

▲ 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

▲ 择要：

褐色脂肪构造（BAT）是一种加热器官，表达产热解偶联卵白1 （UCP1），于低温勒迫下维持高体温。BAT产热被以为是哺乳植物的重要特性，但其进化发源尚不清晰。

咱们发明，约莫1.5亿年前从真植物哺乳植物分解出来的有袋植物的脂肪构造表达一种非产热性的UCP1变体，这类变体由部门转录组BAT特性节制，与真植物米色脂肪构造中发明的相似。咱们发明，重修的真兽先人UCP1序列显示出典型的产热活性，而兽先人UCP1则长短产热的。

是以，哺乳植物脂肪构造产热可能履历了两个差别的进化阶段，于兽类配合先人的产热前阶段将UCP1表达与脂肪构造以及热应激接洽起来。研究者以为，于第二阶段，UCP1得到了其产热功效，出格是于真兽中，是以哺乳植物的BAT产热功效是于与有袋植物分解以后才最先的。

▲ 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 ma妹妹alian trait, but its evolutionary origin is unknown. We show that adipose tissue of marsupials, which diverged from eutherian ma妹妹als ~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 co妹妹on eutherian ancestor displayed typical thermogenic activity, whereas therian ancestor UCP1 is nonthermogenic. Thus, ma妹妹alian adipose tissue thermogenesis may have evolved in two distinct stages, with a prethermogenic stage in the co妹妹on 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 ma妹妹alian BAT thermogenesis occurred only after the divergence from marsupials.

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