《科学》2022年2月25日，第375卷，第6583期

 

 

 

 

 

 

物理学Physics

 

 

A framework for scintillation in nanophotonics

 

纳米光子学的闪烁

 

▲ 作者：CHARLES ROQUES-CARMES, NICHOLAS RIVERA, ALI GHORASHISTEVEN E. KOOI, YANG, ZIN LINJUSTIN BEROZ, AVIRAM MASSUDA, JAMISON SLOAN, etc.

 

▲ 链接：

 

https://www.science.org/doi/10.1126/science.abm9293

 

 

 

▲ 摘要

 

当高能粒子与物质碰撞时，能量被转移到物质中的原子上，就会发光。这种闪烁过程被用于从医学成像到高能粒子物理的许多探测器应用。作者将闪烁材料与纳米光子结构集成在一起，以增强和控制其发光。

 

 

 

他们展示了如何使纳米光子结构形成闪烁的光谱、角和偏振特性。这种方法将有助于开发出更亮、更快和更高分辨率的闪烁体。

 

 

 

▲ Abstract

 

When a high-energy particle collides with a material, the energy is transferred to atoms in the material, and light can be emitted. This scintillation process is used in many detector applications ranging from medical imaging to high-energy particle physics. Roques-Carmes et al. integrated scintillating materials with nanophotonic structures to enhance and control their light emission (see the Perspective by Yu and Fan). The authors show how nanophotonic structures enable the ability to shape the spectral, angular, and polarization characteristics of scintillation. This approach should enable the development of brighter, faster, and higher-resolution scintillators. 

 

 

 

 

 

 

 

 

 

 

 

 

 

Highly stretchable van der Waals thin films for adaptable and breathable electronic membranes

 

高拉伸范德瓦尔薄膜可用作适应性强的电子膜

 

▲ 作者：ZHUOCHENG YAN, DONG XUZHAO, YANG LIN, PEIQI WANG, BOCHENG CAO, HUAYING REN, CHENGZHANG WAN, LAIYUAN WANG, XIANGFENG DUAN

 

▲ 链接：

 

https://www.science.org/doi/10.1126/science.abl8941

 

 

 

▲ 摘要

 

刚性材料在浇铸成薄板时具有更强的柔韧性，但在受到面内旋转或扭转运动时仍会发生碰撞和屈曲，从而不能贴合地覆盖弯曲和可移动的表面。作者通过旋转涂覆含有半导体材料薄片的薄膜，形成了大约10纳米厚的独立薄片。

 

 

 

薄片通过无键范德瓦尔界面相互吸引，以实现机械拉伸、延展性以及透气性。这些特性使它们适用于可监测和放大一系列电生理信号的生物电子膜，比如进行心电图和脑电图演示的生物电子膜。

 

 

 

▲ Abstract

 

Rigid materials become more flexible when cast as thin sheets, but they will still bump and buckle when subjected to in-plane rotation or twisting motions and thus cannot conformally cover a curved and mobile surface. Yan et al. formed roughly 10-nanometer-thick freestanding sheets by spin coating films containing flakes of semiconducting materials. The flakes attract each other through bond-free van der Waals interfaces to enable mechanical stretchability and malleability as well as permeability and breathability. These properties make them suitable for bioelectronic membranes that can monitor and amplify a range of electrophysiological signals, including demonstrations of electrocardiography and electroencephalography. 

 

 

 

 

 

 

 

 

 

 

 

 

 

Black hole spin–orbit misalignment in the x-ray binary MAXI J1820+070

 

X射线双星中的黑洞自旋轨道错位

 

▲ 作者：JURI POUTANEN, ALEXANDRA VELEDINA, ANDREI V. BERDYUGIN, SVETLANA V. BERDYUGINA, HELEN JERMAKPETER G. JONKER, JARI J. E. KAJAVA, ILIA A. KOSENKOV, VADIM KRAVTSOV, SERGEY S. TSYGANKOV

 

▲ 链接：

 

https://www.science.org/doi/10.1126/science.abl4679

 

 

 

▲ 摘要

 

X射线双星系统中黑洞的观测特征取决于它们的质量、自旋、吸积速率以及黑洞自旋和轨道角动量之间的不对位角。本文介绍了X射线双星MAXI J1820+070中黑洞的光学偏振观测，并对其轨道位置角进行了约束。

 

 

 

结合之前对黑洞自旋的相对论喷流方向和轨道倾角的测定，作者确定了自旋-轨道偏差角的下限为40°。

 

 

 

这种不一致一定是由双星演化或黑洞形成阶段引起的。如果其他的X射线双星也有类似的大偏差，这将使X射线观测中黑洞质量和自旋的测量产生偏差。

 

 

 

▲ Abstract

 

The observational signatures of black holes in x-ray binary systems depend on their masses, spins, accretion rate, and the misalignment angle between the black hole spin and the orbital angular momentum. We present optical polarimetric observations of the black hole x-ray binary MAXI J1820+070, from which we constrain the position angle of the binary orbital. Combining this with previous determinations of the relativistic jet orientation, which traces the black hole spin, and the inclination of the orbit, we determine a lower limit of 40° on the spin-orbit misalignment angle. The misalignment must originate from either the binary evolution or black hole formation stages. If other x-ray binaries have similarly large misalignments, these would bias measurements of black hole masses and spins from x-ray observations.

 

 

 

 

 

 

 

 

 

 

 

 

 

Topological modes in a laser cavity through exceptional state transfer

 

在激光腔中实现拓扑模式

 

▲ 作者：A. SCHUMER, Y. G. N. LIU, XJ. LESHINL. DINGY. ALAHMADI, A. U. HASSANH. NASARIS. ROTTER, D. N. CHRISTODOULIDES, M. KHAJAVIKHAN

 

▲ 链接：

 

https://www.science.org/doi/10.1126/science.abl6571

 

 

 

▲ 摘要

 

激光腔是典型的简单结构，泵浦光在腔壁之间对称振荡，理想情况下是单共振输出模式。

 

 

 

利用显示增益和损耗的材料可以实现更复杂的腔体设计，从而导致输出模式可以有效调谐的异常点。作者设计了一种腔体，当泵浦光在腔体内来回传播时，它围绕着特殊点。

 

 

 

其结果是一种激光能够同时发射两种不同的，但在拓扑上相连的横向轮廓，每一种轮廓都来自腔体的不同侧面。该方法为设计拓扑稳健的激光腔提供了灵活性。

 

 

 

▲ Abstract

 

Laser cavities are typically simple structures in the sense that the pump light oscillates between the cavity walls symmetrically, ideally with a single resonant output mode. More complex cavity designs exploiting materials exhibiting gain and loss can be realized that result in an exceptional point at which the output mode can effectively be tuned. Schumer et al. designed a cavity in which the pump light encircles the exceptional point as it propagates back and forth within the cavity. The result is a laser capable of simultaneously emitting in two different, but topologically linked, transverse profiles, each from a different facet of the cavity. The approach provides flexibility in designing topologically robust laser cavities.

 

 

 

 

 

 

 

 

生命科学Life Science

 

 

 

 

 

 

 

 

Hyperexcitable arousal circuits drive sleep instability during aging

 

在衰老过程中，过度兴奋的觉醒回路会导致睡眠不稳定

 

▲ 作者：SHI-BIN LI, VALENTINA MARTINEZ DAMONTE, CHONG CHEN, GORDON X. WANG, REENAL PATTN, LUIS DE LECEA, etc.

 

▲ 链接：

 

https://www.science.org/doi/10.1126/science.abh3021

 

 

 

▲ 摘要

 

对人类来说，随着年龄的增长，睡眠质量下降是最普遍的抱怨之一。作者在一个动物模型中发现，衰老与睡眠期间促进清醒的大脑区域的自发活动增强。

 

 

 

下丘脑泌素表达的神经元在睡眠时更加活跃，增加了短暂觉醒的机会，从而导致睡眠更加分散。衰老脑组织中下丘脑泌素神经元的兴奋性增强，可能与钾通道亚群表达降低有关。

 

 

 

因此，与衰老相关的睡眠碎片可能是由于促进觉醒的神经元内在兴奋性的改变。

 

 

 

▲ Abstract

 

In humans, the deterioration of sleep quality during aging is one of the most prevalent complaints. In an animal model, Li et al. found that aging correlated with enhanced spontaneous activity of wake-promoting brain areas during sleep Hypocretin-expressing neurons were more active during sleep, raising the chances of brief arousals and thus causing sleep to be more fragmented. The excitability of hypocretin neurons in aged brain tissue was heightened, possibly because of decreased expression of a subpopulation of potassium channels. Aging-related sleep fragmentation may therefore be due to altered intrinsic excitability of arousal-promoting neurons. 

 

 

 

 

 

 

 

 

 

 

 

 

 

A unified genealogy of modern and ancient genomes

 

古今人类基因组的统一系谱

 

▲ 作者：ANTHONY WILDER WOHNS, ALI AKBARI, SWAPAN MALLICK, RON PINHASI, NICK PATTERSON, XDAVID REICH, JEROME KELLEHER , GIL MCVEAN, etc.

 

▲ 链接：

 

https://www.science.org/doi/10.1126/science.abi8264

 

 

 

▲ 摘要

 

到目前为止，已经产生了数十万个现代人类基因组和数千个古人类基因组。然而，不同的方法和数据质量使它们之间的比较变得困难。

 

 

 

此外，每个人类基因组都包含来自不同年龄的祖先的片段。作者将树记录方法应用于古代和现代人类基因组，以生成一个统一的人类谱系。

 

 

 

这种方法允许缺失和错误的数据，并能使用古代基因组校准基因组合并时间。这使得科学家能够确定人类的基因组是如何随时间和种群发生变化的。

 

 

 

▲ Abstract

 

Hundreds of thousands of modern human genomes and thousands of ancient human genomes have been generated to date. However, different methods and data quality can make comparisons among them difficult. Furthermore, every human genome contains segments from ancestries of varying ages. Wohns et al. applied a tree recording method to ancient and modern human genomes to generate a unified human genealogy. This method allows for missing and erroneous data and uses ancient genomes to calibrate genomic coalescent times. This permits us to determine how our genomes have changed over time and between populations, informing upon the evolution of our species.