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

一颗低质量恒星四周的星系盘上有丰硕的碳氢化合物

▲ 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

▲ 摘要：

在年夜大都天体中，碳和氧的品貌类似。但是，在冷到足以构成份子的区域，按照它们的相对品貌，终究的化学反映可能富含碳或氧。

研究者操纵中红外光谱研究了一颗年青的低质量恒星四周的原行星盘，发现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。他们会商了发生这类碳富集的可能机制，并提出它可能影响盘内构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

▲ 摘要：

经由过程塑造热辐射的空间和光谱发射特征来节制热辐射在很多科学和工程范畴中起着要害感化。操纵超材料剪裁热发射的传统方式遭到所需亚波长材料布局的有限空间分辩率和材料在红外中的强接收的阻碍。

研究者展现了一种基在拓扑概念的方式。经由过程改变多层涂层的单个参数，他们可以或许节制概况的反射拓扑布局，而且零反射的临界点遭到拓扑庇护。亚临界和超临界空间域之间的鸿沟具有接近同一热辐射率的拓扑界面态。这些拓扑概念使热光在热治理和热假装利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 symmetry 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

▲ 摘要：

由非手性布局构成的自觉镜像对称破缺和出现的极性挨次是在流体中很少不雅察到的现象。它们别离存在在某些向列相液晶中；但是，它们历来没有同时被不雅察到过。研究者陈述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有极性和手性。

值得留意的是，螺旋布局的间距与可见光的波长相当，可以经由过程温度或弱电场的利用进行选择性反射。虽然与螺旋扭弯向列相类似，但这类手性铁电向列相是由电彼此感化引发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

具有明白的手性和相关极性的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

▲ 摘要：

一维过渡金属二硫族化物表示出加强的体光伏效应，在p-n结布局中的太阳能搜集中有跨越Shockley-Queisser极限效力的潜力。但是，这些原型装备的集体输出依然是一个挑战。研究者报导了经由过程原子制造策略合成具有明白手性和相关极性的单晶WS2带阵列。

WS2带的手性由底物耦合为可调扶手型、之型和手性三种类型来界说，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壮大的体光伏效应，进一步集成约1000条具有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

一年生鳉鱼轴的构成

▲ 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的发育揭露了胚胎产生进程中一个迷人的转折。在其他鱼类中，母亲为卵供给产物以肯定胚胎轴，但这些鳉鱼不遵守此原则。

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议身分（一种名为Huluwa的卵白质）的指点下，沿着卵黄分散、堆积并构成体轴。另外，鳉鱼从头操纵了两个主要的旌旗灯号通路Nodal和β-catenin来调和堆积和轴的构成。

这类发育策略可能有助在年生鳉鱼在干旱前提下保存，而且它与合成哺乳动物胚胎的自组织进程具有配合的特点。

▲ 开云体育appAbstract：

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变

▲ 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，表达产热解偶联卵白1 （UCP1），在低温勒迫下保持高体温。BAT产热被认为是哺乳动物的首要特点，但其进化发源尚不清晰。

我们发现，年夜约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，这类变体由部门转录组BAT特点节制，与真动物米色脂肪组织中发现的类似。我们发现，重建的真兽先人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，哺乳动物脂肪组织产热可能履历了两个分歧的进化阶段，在兽类配合先人的产热前阶段将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取得了其产热功能，特殊是在真兽中，是以哺乳动物的BAT产热功能是在与有袋动物分化以后才最先的。

▲ 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 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.

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