Science, 28 June  2024, Volume 384 Issue 6703

《科学》,  2024年6月28日，第384卷，6703期

物理学Physics

Simulations predict intermediate-mass black hole formation in globular clusters

模拟预测球状星团中中等质量黑洞的形成

▲ 作者：MICHIKO S. FUJII, LONG WANG, ATARU TANIKAWA, YUTAKA HIRAI, AND TAKAYUKI R. SAITOH

▲ 链接：

https://www.science.org/doi/10.1126/science.adi4211

▲ 摘要：

中等质量黑洞的质量介于102到105个太阳质量之间，比超新星产生的恒星质量黑洞大，但比在星系中心发现的超大质量黑洞小。目前还不清楚中等质量黑洞是如何形成的。一种可能性是通过较小的黑洞合并，但这一过程的模拟没有达到足够高的质量。

研究者模拟了球状星团的形成，球状星团是由数百万颗恒星组成的大型引力组合。在早期，星团核心的高密度导致了恒星合并，产生了一颗超大质量恒星。当这颗恒星到达生命的尽头时，它坍缩直接形成了一个中等质量黑洞。

▲ Abstract：

Intermediate-mass black holes (IMBHs) are between 102 and 105 solar masses—larger than the stellar-mass black holes produced by supernovae but smaller than the supermassive black holes found at the centers of galaxies. It is unclear how an IMBH could form. One possibility is through the mergers of smaller black holes, but simulations of that process do not reach high enough masses. Fujii et al. simulated the formation of globular clusters, large gravitationally bound assemblages of millions of stars. At early times, the high density at the cluster core caused stellar mergers, producing a single supermassive star. When that star reached the end of its life, it collapsed to directly form an IMBH.

Heterogeneous field response of hierarchical polar laminates in relaxor ferroelectrics

弛豫铁电体中层次极性层板的非均匀场响应

▲ 作者：HAO ZHENG, TAO ZHOU, DINA SHEYFER, JIEUN KIM, JIYEOB KIM, TRAVIS D. FRAZER, ZHONGHOU CAI, MARTIN V. HOLT, ZHAN ZHANG, AND YUE CAO

▲ 链接：

https://www.science.org/doi/10.1126/science.ado4494

▲ 摘要：

弛豫铁电体是一类对外部电场具有吸引极化响应的材料。这一特性对广泛的潜在应用具有吸引力。了解弛豫铁电体优异机电响应的微观起源不仅需要了解极性纳米畴（PNDs）的原子尺度形成，还需要了解PNDs在较长距离上的排列和受激响应的规则。

研究者利用X射线相干纳米衍射，展示了PNDs在弛豫铁电（PMN-0.32PT）中交错自组装成单向介观结构，并称之为极性层合。研究揭示了层内和层间PND的高度非均质电场驱动响应，并建立了它们与局部应变和PND壁性质的相关性。该观察结果强调了层次晶格组织对宏观材料性质的关键作用，为理解和设计弛豫剂以及广泛的量子和功能材料提供了指导原则。

▲ Abstract：

Relaxor ferroelectrics are a class of materials that have an attractive polarization response to an external electric field. This property is attractive for a wide range of potential applications. Understanding the microscopic origin of the superior electromechanical response in relaxor ferroelectrics requires knowledge not only of the atomic-scale formation of polar nanodomains (PNDs) but also the rules governing the arrangements and stimulated response of PNDs over longer distances. Using x-ray coherent nanodiffraction, we show the staggered self-assembly of PNDs into unidirectional mesostructures that we refer to as polar laminates in the relaxor ferroelectric PMN-0.32PT. We reveal the highly heterogeneous electric-field–driven responses of intra- and interlaminate PNDs and establish their correlation with the local strain and the nature of the PND walls. Our observations highlight the critical role of hierarchical lattice organizations on macroscopic material properties and provide guiding principles for the understanding and design of relaxors and a wide range of quantum and functional materials.

化学Chemistry

Molecular recognition with resolution below 0.2 angstroms through thermoregulatory oscillations in covalent organic frameworks

通过共价有机框架中的温度调节振荡进行分辨率低于0.2埃的分子识别

▲ 作者：YIMING HU, BRATIN SENGUPTA, HAI LONG, LACEY J. WAYMENT, RICHARD CIORA, YINGHUA JIN, JINGYI WU, ZEPENG LEI, KALEB FRIEDMAN, AND WEI ZHANG

▲ 链接：

https://www.science.org/doi/10.1126/science.adj8791

▲ 摘要：

气体分离通常是用固体膜来完成的，因为很难制造出具有足够小孔隙的多孔膜来分离具有相似原子大小的气体。研究者通过聚合带有四苯基硼酸键的单体，合成了一系列离子共价有机框架（ICOF）材料。

这些ICOFs表现出一种温度依赖的连接振荡，允许通过由于孔隙振动而排斥一些分子来动态控制孔径，分辨率低至0.2埃。研究者展示了大小依赖的分子识别和分离工业相关气体（O?, N?, CH?, CO?和H?）。

▲ Abstract：

Gas separation is often done using solid membranes because it is hard to make porous ones with pores small enough to separate between gases that have similar atomic sizes. Hu et al. synthesized a series of ionic covalent organic framework (ICOF) materials by polymerizing monomers with tetraphenylborate linkages. These ICOFs exhibited a temperature-dependent linker oscillation that allows for dynamic control of the pore size through the rejection of some molecules due to the vibrations of the pores, with resolution down to 0.2 angstroms. The authors demonstrate size-dependent molecular recognition and separation of industry-relevant gases (O?, N?, CH?, CO?和H?). 

Structure of methylaluminoxane (MAO): Extractable [Al(CH?)?]+ for precatalyst activation

甲基铝氧烷的结构：可萃取的 [Al(CH?)?]+预催化剂活化

▲ 作者：LUBIN LUO, JAROD M. YOUNKER, AND ALEXANDER V. ZABULA

▲ 链接：

https://www.science.org/doi/10.1126/science.adm7305

▲ 摘要：

几十年来，现代塑料工业一直依靠甲基铝氧烷来激活聚合催化剂。甲基铝氧烷是一种由铝、氧和甲基组成的神秘化合物。尽管甲基铝氧烷在如此大规模的制造中处于中心地位，但其团聚行为彻底阻碍了其详细的结构表征。

研究者报道了甲基铝氧烷的结晶和X射线衍射分析，揭示了二维薄片的排列。聚合催化剂活化的量子化学模拟和实验测试进一步支持了活性位点的分配。

▲ Abstract：

The modern plastics industry has relied for decades on methylaluminoxane, a mysterious compound of aluminum, oxygen, and methyl groups, to activate polymerization catalysts. Despite the centrality of methylaluminoxane to such high-volume manufacturing, its agglomeration behavior has thoroughly hindered its detailed structural characterization. Luo et al. report crystallization of methylaluminoxane and x-ray diffraction analysis to reveal a two-dimensional sheet arrangement. The active-site assignments were further supported by quantum chemical simulations and experimental tests of polymerization catalyst activation. 

生物学Biology

Homeocurvature adaptation of phospholipids to pressure in deep-sea invertebrates

深海无脊椎动物磷脂对压力的等曲率适应

▲ 作者：JACOB R. WINNIKOFF, DANIEL MILSHTEYN, SASIRI J. VARGAS-URBANO, MIGUEL A. PEDRAZA-JOYA, AARON M. ARMANDO, OSWALD QUEHENBERGER, ALEXANDER SODT, RICHARD E. GILLILAN, EDWARD A. DENNIS, AND ITAY BUDIN

▲ 链接：

https://www.science.org/doi/10.1126/science.adm7607

▲ 摘要：

静水压力随着海洋深度的增加而增加，但人们对生物耐压能力的分子基础知之甚少。研究者描述了栉水母的压力适应模式，这限制了这些动物的深度范围。深海栉水母脂质结构分析表明，它们在不稳定的压力下形成非双层相。

脂质组学和全原子模拟鉴定了具有强负自发曲率的磷脂，包括磷脂原，作为引起这种相行为的深度适应膜的标志。缩醛原的合成增强了大肠杆菌的耐压能力，而低曲率脂质则有相反的效果。栉水母组织的成像表明，深海动物在减压时的解体可能是由磷脂膜的相变驱动的。

▲ Abstract：

Hydrostatic pressure increases with depth in the ocean, but little is known about the molecular bases of biological pressure tolerance. We describe a mode of pressure adaptation in comb jellies (ctenophores) that also constrains these animals’ depth range. Structural analysis of deep-sea ctenophore lipids shows that they form a nonbilayer phase at pressures under which the phase is not typically stable. Lipidomics and all-atom simulations identified phospholipids with strong negative spontaneous curvature, including plasmalogens, as a hallmark of deep-adapted membranes that causes this phase behavior. Synthesis of plasmalogens enhanced pressure tolerance in Escherichia coli, whereas low-curvature lipids had the opposite effect. Imaging of ctenophore tissues indicated that the disintegration of deep-sea animals when decompressed could be driven by a phase transition in their phospholipid membranes.

古生物学Paleontology

Rapid volcanic ash entombment reveals the 3D anatomy of Cambrian trilobites

快速火山灰掩埋揭示了寒武纪三叶虫的三维解剖结构

▲ 作者：ABDERRAZAK EL ALBANI, ARNAUD MAZURIER, GREGORY D. EDGECOMBE, ABDELFATTAH AZIZI, ASMAA EL BAKHOUCH, HARRY O. BERKS, EL HAFID BOUOUGRI, IBTISSAM CHRAIKI, PHILIP C. J. DONOGHUE, AND JOHN R. PATERSON

▲ 链接：

https://www.science.org/doi/10.1126/science.adl4540

▲ 摘要：

三叶虫可能是寒武纪最著名的居民。从寒武纪早期到二叠纪灭绝的大量化石记录中，我们可以很好地识别出它们独特的化石外部形态。然而，绝大多数三叶虫化石只显示出外部形态，对它们的内部形态知之甚少。

研究者描述了因为水下火山碎屑流导致的快速死亡后保存形成的几种三叶虫化石。这些保存创造了具有非常完好解剖结构的三维化石。对三叶虫解剖结构的进一步了解揭示了一些新的特征，并为冠类真节肢动物提供了关键的见解。

▲ Abstract：

Trilobites are probably the best known denizens of the Cambrian Period. Their distinctive fossilized external forms are well recognized from an extensive fossil record spanning the early Cambrian to the Permian extinction. The vast majority of trilobite fossils display only external morphology, however, leaving much unknown about their internal morphology. El Albani et al. describe several trilobite fossils created by rapid death and preservation due to an underwater pyroclastic flow. This preservation created three-dimensional fossils with a remarkably well-preserved anatomy. This enhanced understanding of trilobite anatomy has revealed several new features and provided key insights into crown group euarthropods.