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发布日期：2024-08-19 作者：开博
Science,28June2024,Volume384Issue6703
《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
摹拟猜测球状星团中中等质量黑洞的构成
▲ 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在102到105个太阳质量之间，比超新星发生的恒星质量黑洞年夜，但比在星系中间发现的超年夜质量黑洞小。今朝还不清晰中等质量黑洞是若何构成的。一种可能性是经由过程较小的黑洞归并，但这一进程的摹拟没有到达足够高的质量。
研究者摹拟了球状星团的构成，球状星团是由数百万颗恒星构成的年夜型引力组合。在初期，星团焦点的高密度致使了恒星归并，发生了一颗超年夜质量恒星。当这颗恒星达到生命的终点时，它坍缩直接构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 sup开博体育ermassive 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
弛豫铁电体中条理极性层板的非平均场响应
▲ 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。这一特征对普遍的潜伏利用具有吸引力。领会弛豫铁电体优良电机响应的微不雅发源不但需要领会极性纳米畴（PNDs）的原子标准构成，还需要领会PNDs在较长距离上的摆列和受激响应的法则。
研究者操纵X射线相关纳米衍射，展现了PNDs在弛豫铁电（PMN-0.32PT）中交织自组装成单向介不雅布局，并称之为极性层合。研究揭露了层内和层间PND的高度非均质电场驱动响应，并成立了它们与局部应变和PND壁性质的相干性。该不雅察成果强调了条理晶格组织对宏不雅材料性质的要害感化，为理解和设计弛豫剂和普遍的量子和功能材料供给了指点原则。
▲ 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
经由过程共价有机框架中的温度调理振荡进行分辩率低在0.2埃的份子辨认
▲ 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：
气体分手凡是是用固体膜来完成的，由于很难制造出具有足够小孔隙的多孔膜来分手具有类似原子巨细的气体。研究者经由过程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表示出一种温度依靠的毗连振荡，答应经由过程因为孔隙振动而排挤一些份子来动态节制孔径，分辩率低至0.2埃。研究者展现了巨细依靠的份子辨认和分手工业相干气体（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
甲基铝氧烷的布局：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，现代塑料工业一向依托甲基铝氧烷来激活聚合催化剂。甲基铝氧烷是一种由铝、氧和甲基构成的神秘化合物。虽然甲基铝氧烷在如斯年夜范围的制造中处在中间地位，但其团圆行动完全阻碍了其具体的布局表征。
研究者报导了甲基铝氧烷的结晶和X射线衍射阐发，揭露了二维薄片的摆列。聚合催化剂活化的量子化学摹拟和尝试测试进一步撑持了活性位点的分派。
▲ 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顺应
▲ 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：
静水压力跟着海洋深度的增添而增添，但人们对生物耐压能力的份子根本知之甚少。研究者描写了栉水母的压力顺应模式，这限制了这些动物的深度规模。深海栉水母脂质布局阐发注解，它们在不不变的压力下构成非双层相。
脂质组学和全原子摹拟判定了具有强负自觉曲率的磷脂，包罗磷脂原，作为引发这类相行动的深度顺应膜的标记。缩醛原的合成加强了年夜肠杆菌的耐压能力，而低曲率脂质则有相反的结果。栉水母组织的成像注解，深海动物在减压时的解体多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
快速火山灰掩埋揭露了寒武纪三叶虫的三维剖解布局
▲ 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：
三叶虫多是寒武纪最闻名的居平易近。从寒武纪初期到二叠纪灭尽的年夜量化石记实中，我们可以很好地辨认出它们怪异的化石外部形态。但是，绝年夜大都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。
研究者描写了由于水下火山碎屑流致使的快速灭亡后保留构成的几种三叶虫化石。这些保留缔造了具有很是无缺剖解布局的三维化石。对三叶虫剖解布局的进一步领会揭露了一些新的特点，并为冠类真节肢动物供给了要害的看法。
▲ 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.
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