编译 | 李言

Nature, 12 January 2023, Volume 613 Issue 7943

《自然》2023年1月12日，第613卷，7943期

天文学Astronomy

Kilohertz quasiperiodic oscillations in short gamma-ray bursts

短伽马射线暴中的千赫兹准周期振荡

▲ 作者：Cecilia Chirenti, Simone Dichiara, Amy Lien, M. Coleman Miller & Robert Preece

▲ 链接：

https://www.nature.com/articles/s41586-022-05497-0

▲ 摘要：

短伽马射线暴（GRBs）与双中子星并合有关，是一种在引力波和多波段电磁频谱中都有观测到的多信使天文事件。根据双星中恒星的质量和它们大部分未知的状态方程的细节，在合并后可能会形成一颗动态演化的短寿命中子星，在坍缩成黑洞之前存在大约10-300毫秒。

不同组的数值相对论模拟一致地显示了合并后引力波信号在1-5千赫范围内的广泛功率谱特征，目前的引力波探测器无法探测到，但未来十年中的第三代地基探测器可能会观测到。

这意味着在中子星最终坍缩成黑洞之前不久形成的小事件中，发射伽马射线的准周期调制的可能性。在此，我们展示了来自于暴发和瞬态源实验（BATSE）数据的GRB 910711和GRB 931101B的信号，它们与数值相对论的预测是一致的。

▲ Abstract：

Short gamma-ray bursts (GRBs) are associated with binary neutron star mergers, which are multimessenger astronomical events that have been observed both in gravitational waves and in the multiband electromagnetic spectrum. Depending on the masses of the stars in the binary and on details of their largely unknown equation of state, a dynamically evolving and short-lived neutron star may be formed after the merger, existing for roximately 10–300 ms before collapsing to a black hole. Numerical relativity simulations across different groups consistently show broad power spectral features in the 1–5-kHz range in the post-merger gravitational-wave signal, which is inaccessible by current gravitational-wave detectors but could be seen by future third-generation ground-based detectors in the next decade. This implies the possibility of quasiperiodic modulation of the emitted gamma rays in a subset of events in which a neutron star is formed shortly before the final collapse to a black hole. Here we present two such signals identified in the short bursts GRB 910711 and GRB 931101B from archival Burst and Transient Source Experiment (BATSE) data, which are compatible with the predictions from numerical relativity.

材料科学Materials Science

Enhanced superconductivity in spin–orbit proximitized bilayer graphene

自旋轨道近似双层石墨烯的超导性增强

▲ 作者：Yiran Zhang, Robert Polski, Alex Thomson et al.

▲ 链接：

https://www.nature.com/articles/s41586-022-05446-x

▲ 摘要：

在此，我们展示了在伯纳尔堆叠的双层石墨烯（BLG）上放置单层二硒化钨（WSe2）可以极大地促进库珀对：零磁场环境下，超导性在临界温度中表现出增强了一个数量级，并且发生在一个更宽的8倍的密度范围内。

通过将BLG-WSe2中的量子振荡映射为电场和掺杂的函数，我们在正常状态极化的区域确立了超导性，其中四种自旋谷中有两种主要分布。平面内磁场测量进一步揭示了BLG-WSe2中的超导表现出对掺杂的临界场的显著依赖，在超导穹顶的一端服从泡利极限，在另一端则不然。

此外，只有垂直电场将BLG空穴波函数推向WSe2时才会产生超导性，这表明近距离诱导（伊辛）自旋-轨道耦合在稳定配对中起着关键作用。

▲ Abstract

Here we show that placing monolayer tungsten diselenide (WSe2) on BLG promotes Cooper pairing to an extraordinary degree: superconductivity ears at zero magnetic field, exhibits an order of magnitude enhancement in Tc and occurs over a density range that is wider by a factor of eight. By ming quantum oscillations in BLG–WSe2 as a function of electric field and doping, we establish that superconductivity emerges throughout a region for which the normal state is polarized, with two out of four spin-valley flavours predominantly populated. In-plane magnetic field measurements further reveal that superconductivity in BLG–WSe2 can exhibit striking dependence of the critical field on doping, with the Chandrasekhar–Clogston (Pauli) limit roughly obeyed on one end of the superconducting dome, yet sharply violated on the other. Moreover, the superconductivity arises only for perpendicular electric fields that push BLG hole wavefunctions towards WSe2, indicating that proximity-induced (Ising) spin–orbit coupling plays a key role in stabilizing the pairing.

化学Chemistry

A ligand insertion mechanism for cooperative NH3 capture in metal–organic frameworks

一种可以在金属有机框架中捕获 NH3 的配体插入机制

▲ 作者：Benjamin E. R. Snyder, Ari B. Turkiewicz, Hiroyasu Furukawa et al.

▲ 链接：

https://www.nature.com/articles/s41586-022-05409-2

▲ 摘要：

在这里，我们报告一种通过协同插入到金属-羧酸键中可逆地结合氨，形成致密的一维配位聚合物的可调的三维框架。这种不寻常的吸附机制提供了相当可观的本征热管理，并且，在高压和高温下可协同氨吸收产生强大的容量。

通过简单的合成改性，氨吸附的阈值压力可进一步调整近五个数量级，这一点为开发节能氨吸附剂指明了更广阔的策略。

▲ Abstract：

Here we report a tunable three-dimensional framework that reversibly binds ammonia by cooperative insertion into its metal–carboxylate bonds to form a dense, one-dimensional coordination polymer. This unusual adsorption mechanism provides considerable intrinsic thermal management, and, at high pressures and temperatures, cooperative ammonia uptake gives rise to large working capacities. The threshold pressure for ammonia adsorption can further be tuned by almost five orders of magnitude through simple synthetic modifications, pointing to a broader strategy for the development of energy-efficient ammonia adsorbents.

地理学Geography

Seasonal temperatures in West Antarctica during the Holocene

全新世时期南极洲西部的季节温度

▲ 作者：Tyler R. Jones, Kurt M. Cuffey, William H. G. Roberts et al.

▲ 链接：

https://www.nature.com/articles/s41586-022-05411-8

▲ 摘要：

在此，我们分析了来自南极冰盖西部分水岭冰芯的水同位素比率的连续记录，以揭示过去11000年以来该地在夏季及冬季的温度变化。全新世早期至中期，南极洲西部的夏季温度一直在上升，于4100年前达到峰值，而后下降到现在的水平。

气候模型模拟表明，这些变化主要反映了夏季最大日照的变化，证实了季节日照与变暖之间的联系，并证明了日照强度——而非季节性综合日照或季节持续时间——的重要性。冬季气温总体变化较小，与日照强迫的预测一致。但这一指标在全新世早期也有所波动，这可能是由于经向热输送的变化。

夏季和冬季温度变化的幅度限制了南极西部冰盖表面的融化，其自全新世早期以来下降到不足162米，或者可能不足58米，与南极洲西部其他地方的地质限制相一致。

▲ Abstract：

Here, we analyse a continuous record of water-isotope ratios from the West Antarctic Ice Sheet Divide ice core to reveal summer and winter temperature changes through the last 11,000?years. Summer temperatures in West Antarctica increased through the early-to-mid-Holocene, reached a peak 4,100?years ago and then decreased to the present. Climate model simulations show that these variations primarily reflect changes in maximum summer insolation, confirming the general connection between seasonal insolation and warming and demonstrating the importance of insolation intensity rather than seasonally integrated insolation or season duration. Winter temperatures varied less overall, consistent with predictions from insolation forcing, but also fluctuated in the early Holocene, probably owing to changes in meridional heat transport. The magnitudes of summer and winter temperature changes constrain the lowering of the West Antarctic Ice Sheet surface since the early Holocene to less than 162?m and probably less than 58?m, consistent with geological constraints elsewhere in West Antarctica.

Grain shape effects in bed load sediment transport

颗粒形状在推移质输沙中的影响

▲ 作者：Eric Deal, Jeremy G. Venditti, Santiago J. Benavides, Ryan Bradley, Qiong Zhang, Ken Kamrin & J. Taylor Perron

▲ 链接：

https://www.nature.com/articles/s41586-022-05564-6

▲ 摘要：

我们发现，相较于泥沙输送数据集合的分散程度，颗粒形状会对推移质输沙率产生很多影响。我们提出了一个理论，可以解释颗粒形状对流体阻力和颗粒摩擦的影响，同时预测了运输的开始和效率取决于运输颗粒的阻力系数和体摩擦系数。

实验室实验证实了这些预测，同时揭示了很难从颗粒的外观直观地判断颗粒形状对于输沙率的影响。我们提出了一种形状校正的输沙规律，其超出了我们的实验测量范围。我们的研究结果能使输沙的预测更加准确，并有助于将球形颗粒的理论与自然沉积物颗粒的实际情况相协调。

▲ Abstract：

Here we show that grain shape can modify bed load transport rates by an amount comparable to the scatter in many sediment transport datasets. We develop a theory that accounts for grain shape effects on fluid drag and granular friction and predicts that the onset and efficiency of transport depend on the coefficients of drag and bulk friction of the transported grains. Laboratory experiments confirm these predictions and reveal that the effect of grain shape on sediment transport can be difficult to intuit from the earance of grains. We propose a shape-corrected sediment transport law that collapses our experimental measurements. Our results enable greater accuracy in predictions of sediment transport and help reconcile theories developed for spherical particles with the behaviour of natural sediment grains.

Periclase deforms more slowly than bridgmanite under mantle conditions

在地幔条件下，方镁石的变形比布氏岩慢

▲ 作者：Patrick Cordier, Karine Gouriet, Timmo Weidner, James Van Orman, Olivier Castelnau, Jennifer M. Jackson & Philippe Carrez

▲ 链接：

https://www.nature.com/articles/s41586-022-05410-9

▲ 摘要：

在这项研究中，我们采用2.5维位错动力学方法模拟了氧化镁方镁石在低地幔压力和低温度下的低应力蠕变。我们展示了，方镁石在这些条件下变形非常缓慢，尤其是比攀移蠕变的布氏岩变形慢得多。

在积聚环境中，这种次生相几乎不参与变形，因此下地幔的流变学可以很好地用布氏岩的流变学来描述。我们的结果表明，变形机制的剧烈变化可以作为应变率的函数发生。

▲ Abstract：

In this work we use 2.5-dimensional dislocation dynamics to model the low-stress creep of MgO periclase at lower mantle pressures and temperatures. We show that periclase deforms very slowly under these conditions, in particular, much more slowly than bridgmanite deforming by pure climb creep. This is due to slow diffusion of oxygen in periclase under pressure. In the assemblage, this secondary phase hardly participates in the deformation, so that the rheology of the lower mantle is very well described by that of bridgmanite. Our results show that drastic changes in deformation mechanisms can occur as a function of the strain rate.