物理学Physics

A rotating white dwarf shows different compositions on its opposite faces

一颗扭转白矮星相对面显现分歧成份

▲ 作者：Ilaria Caiazzo, Kevin B. Burdge, Dayal Wickramasinghe, Vikram S. Dhillon, Stuart P. Littlefair, James Munday, Ingrid Pelisoli, Daniel Perley, Dave I. Sahman

▲ 链接：

https://www.nature.com/articles/s41586-023-06171-9

▲ 摘要：

白矮星是年夜大都恒星灭亡后留下的密度极高的残留物，其质量与太阳质量相当，可紧缩成类地行星巨细。

研究者陈述了对ZTF J203349.8+322901.1的不雅测，这是一颗过渡白矮星，有两个面：其年夜气层一面由氢主导，另外一面由氦主导。这类非凡性质多是由一个小磁场的存在引发的，在其概况上造成了温度、压力或夹杂强度的不平均性。

ZTF J203349.8+322901.1多是一类磁性过渡白矮星中最极真个成员，与其近似的还白矮星GD 323，后者显示出与此类似但更奥妙的转变。这类白矮星有助在揭露白矮星光谱演变背后的物理机制。

▲ Abstract：

White dwarfs, the extremely dense remnants left behind by most stars after their death, are characterized by a mass comparable to that of the Sun compressed into the size of an Earth-like planet. Here we report observations of ZTF?J203349.8+322901.1, a transitioning white dwarf with two faces: one side of its atmosphere is dominated by hydrogen and the other one by helium. This peculiar nature is probably caused by the presence of a small magnetic field, which creates an inhomogeneity in temperature, pressure or mixing strength over the surface. ZTF?J203349.8+322901.1 might be the most extreme member of a class of magnetic, transitioning white dwarfs together with GD?323, a white dwarf that shows similar but much more subtle variations. This class of white dwarfs could help shed light on the physical mechanisms behind the spectral evolution of white dwarfs.

3D integration enables ultralow-noise isolator-free lasers in silicon photonics

3D集成让硅光子学中超低噪声无隔离器激光器成为可能

▲ 作者：Chao Xiang, Warren Jin, Osama Terra, Bozhang Dong, Heming Wang, Lue Wu, Joel Guo, Theodore J. Morin, Eamonn Hughes, Jonathan Peters, Qing-Xin Ji, Avi Feshali, Mario Paniccia, Kerry J. Vahala John E. Bowers

▲ 链接：

https://www.nature.com/articles/s41586-023-06251-w

▲ 摘要：

光子集成电路普遍利用在电信和数据中间互连等范畴。但是，在诸如微波合成器、光学陀螺仪和原子钟等光学系统中，光子集成电路虽然在尺寸、重量、功耗和本钱方面具有优势，但仍被认为是次等的解决方案。

这类高精度和高度相关的利用有益在超低噪声激光源与其他光子元件以紧凑而坚忍的摆列情势集成在一路 即在单个芯片上 用在光子集成电路，以代替年夜块的光学和光纤。有两个首要问题阻碍了这类假想的光子集成电路的实现：半导体激光器的高相位噪声和在芯片上直接集成光隔离器的坚苦。

研究者经由过程操纵三维集成来挑战这类老例，从而发生具有没有隔离器操作的硅光子学超低噪声激光器。因为超高质量因子腔，研究所演示的光子集成电路进入了一种不需要光隔离器而发生超低噪声激光器和微波合成器的状况。

这类光子集成电路还为复杂功能和批量出产供给了优胜的可扩大性，并跟着时候的推移提高了不变性和靠得住性。超低消耗光子集成电路的三维集成标记着向硅基复杂系统和收集迈出了要害的一步。

▲ Abstract：

Photonic integrated circuits are widely used in applications such as telecommunications and data-centre interconnects. However, in optical systems such as microwave synthesizers, optical gyroscopes and atomic clocks, photonic integrated circuits are still considered inferior solutions despite their advantages in size, weight, power consumption and cost. Such high-precision and highly coherent applications favour ultralow-noise laser sources to be integrated with other photonic components in a compact and robustly aligned format that is, on a single chip for photonic integrated circuits to replace bulk optics and fibres. There are two major issues preventing the realization of such envisioned photonic integrated circuits: the high phase noise of semiconductor lasers and the difficulty of integrating optical isolators directly on-chip. Here we challenge this convention by leveraging three-dimensional integration that results in ultralow-noise lasers with isolator-free operation for silicon photonics. Through multiple monolithic and heterogeneous processing sequences, direct on-chip integration of III V gain medium and ultralow-loss silicon nitride waveguides with optical loss around 0.5?decibels per metre are demonstrated. Consequently, the demonstrated photonic integrated circuit enters a regime that gives rise to ultralow-noise lasers and microwave synthesizers without the need for optical isolators, owing to the ultrahigh-quality-factor cavity. Such photonic integrated circuits also offer superior scalability for complex functionalities and volume production, as well as improved stability and reliability over time. The three-dimensional integration on ultralow-loss photonic integrated circuits thus marks a critical step towards complex systems and networks on silicon.

化学Chemistry

Ultrafast deposition of faceted lithium polyhedra by outpacing SEI formation

锂多面体的超快沉积

▲ 作者：Xintong Yuan, Bo Liu, Matthew Mecklenburg Yuzhang Li

▲ 链接：

https://www.nature.com/articles/s41586-023-06235-w

▲ 摘要：

电沉积锂（Li）金属对高能电池相当主要。但是，同时构成的概况侵蚀膜 固体电解质界面（SEI）使沉积进程复杂化，这使得对锂金属电沉积的理解很差。研究者经由过程在超快沉积电流密度下超出SEI构成，同时避免质量输运限制，将这两个交叉在一路的进程解耦。

经由过程利用低温电子显微镜，研究者发现金属锂的内涵沉积形态是一个菱形十二面体，这是使人惊奇的自力在电解质化学或电流集电极衬底。

在硬币电池布局中，这些菱形十二面体与电流搜集器表示出接近点接触的毗连，这可以加快非活性锂的构成。研究者提出了一种脉冲电流方案，经由过程操纵锂菱形十二面体作为成核种子来降服这类掉效模式，使致密锂的后续发展与基线比拟提高了电池机能。

固然在曩昔的研究中，锂沉积和SEI构成一向慎密相连，但新尝试方式为从底子上理解这些彼此分手的进程供给了新的机遇，并为设计更好的电池带来了新的看法。

▲ Abstract：

Electrodeposition of lithium (Li) metal is critical for high-energy batteries. However, the simultaneous formation of a surface corrosion film termed the solid electrolyte interphase (SEI) complicates the deposition process, which underpins our poor understanding of Li metal electrodeposition. Here we decouple these two intertwined processes by outpacing SEI formation at ultrafast deposition current densities while also avoiding mass transport limitations. By using cryogenic electron microscopy, we discover the intrinsic deposition morphology of metallic Li to be that of a rhombic dodecahedron, which is surprisingly independent of electrolyte chemistry or current collector substrate. In a coin cell architecture, these rhombic dodecahedra exhibit near point-contact connectivity with the current collector, which can accelerate inactive Li formation8. We propose a pulse-current protocol that overcomes this failure mode by leveraging Li rhombic dodecahedra as nucleation seeds, enabling the subsequent growth of dense Li that improves battery performance compared with a baseline. While Li deposition and SEI formation have always been tightly linked in past studies, our experimental approach enables new opportunities to fundamentally understand these processes decoupled from each other and bring about new insights to engineer better batteries.

Synthesis and properties of cyclic sandwich compounds

环状夹层化合物的合成和性质

▲ 作者：Luca M nzfeld, Sebastian Gillhuber, Adrian Hauser, Sergei Lebedkin, Pauline H?dinger, Nicolai D. Kn?fel, Christina Zovko, Michael T. Gamer, Florian Weigend, Manfred M. Kappes Peter W. Roesky

▲ 链接：

https://www.nature.com/articles/s41586-023-06192-4

▲ 摘要：

状纳米夹层共同物由单个构建块组装而成。研究者展现了设计、合成和表征一个同构系列的圆形夹心化合物，其术语为 环茂烯 。这些环烯烃由18个反复单位构成，在固体状况下构成几近抱负的圆形封锁环。

量子化学计较认为，离子金属-配体键之间的怪异彼此感化，配系统统的体积和环闭应时的能量增益，这是由色散彼此感化的要害影响，增进了这些轮回系统的构成。

到今朝为止，只有线性一维多层夹层化合物被研究用在纳米线等潜伏利用。这个教科书式的环状夹层化合物的例子有望为进一步立异新的功能有机金属材料打开年夜门。

▲ Abstract：

Cyclic nanometre-scale sandwich complexes assembled from individual building blocks were synthesized.Here we show the design, synthesis and characterization of an isomorphous series of circular sandwich compounds, for which the term cyclocenes is suggested. These cyclocenes consist of 18 repea金年会ting units, forming almost ideally circular, closed rings in the solid state, that can be described by the general formula . Quantum chemical calculations lead to the conclusion that a unique interplay between the ionic metal-to-ligand bonds, the bulkiness of the ligand system and the energy gain on ring closure, which is crucially influenced by dispersion interactions, facilitate the formation of these cyclic systems. Up to now, only linear one-dimensional multidecker sandwich compounds have been investigated for possible applications such as nanowires. This textbook example of cyclic sandwich compounds is expected to open the door for further innovations towards new functional organometallic materials.

地质和蔼候Climate Geology

Remote detection of a lunar granitic batholith at Compton Belkovich

月球花岗岩基的长途探测

▲ 作者：Matthew A. Siegler, Jianqing Feng, Katelyn Lehman-Franco, Jeffery C. Andrews-Hanna, Rita C. Economos, Michael St. Clair, Chase Million, James W. Head, Timothy D. Glotch Mackenzie N. White

▲ 链接：

https://www.nature.com/articles/s41586-023-06183-5

▲ 摘要：

除地球，太阳系中几近没有花岗岩。在岩浆系统中取得花岗岩构成需要多阶段的熔融和分选，这也增添了放射性成因元素的浓度。地球上丰硕的水和板块组织增进了这些进程，帮忙从头熔化。

固然在月球上没有这些驱动身分，但已发现了小的花岗岩样本，但它们的发源和它们所代表的系统范围的细节是未知的。研究者陈述了一个异常热地热源的微波波长丈量，最好的注释是在富钍的远侧特点康普顿-贝尔科维奇下面存在一个直径约50千米的花岗岩系统。被动微波辐射丈量对多个波长深度的综合热梯度很敏感。

嫦娥一号和嫦娥二号微波仪器的3 - 37千兆赫天线温度可以或许丈量到每平方米约180毫瓦的峰值热通量，这年夜约是月球高地平均热通量的20倍。这一惊人的范围和地舆规模注解，在月球上，特殊是在Procellarum地域以外，存在一个近似地球的、进化的花岗岩系统，其范围比人们认为的要年夜很多。

另外，这些方式是可推行的：近似被动辐射丈量数据的利用可以极年夜地扩大我们对月球和其他行星上地热进程的熟悉。

▲ Abstract：

Granites are nearly absent in the Solar System outside of Earth. Achieving granitic compositions in magmatic systems requires multi-stage melting and fractionation, which also increases the concentration of radiogenic elements. Abundant water and plate tectonics facilitate these processes on Earth, aiding in remelting. Although these drivers are absent on the Moon, small granite samples have been found, but details of their origin and the scale of systems they represent are unknown. Here we report microwave-wavelength measurements of an anomalously hot geothermal source that is best explained by the presence of an approximately 50-kilometre-diameter granitic system below the thorium-rich farside feature known as Compton Belkovich. Passive microwave radiometry is sensitive to the integrated thermal gradient to several wavelengths depth. The 3 37-gigahertz antenna temperatures of the Chang e-1 and Chang e-2 microwave instruments allow us to measure a peak heat flux of about 180?milliwatts per square metre, which is about 20 times higher than that of the average lunar highlands3,4. The surprising magnitude and geographic extent of this feature imply an Earth-like, evolved granitic system larger than believed possible on the Moon, especially outside of the Procellarum region5. Furthermore, these methods are generalizable: similar uses of passive radiometric data could vastly expand our knowledge of geothermal processes on the Moon and other planetary bodies.

Fennoscandian tree-ring anatomy shows a warmer modern than medieval climate

树木年轮剖解显示，现代天气比中世纪天气更暖和

▲ 作者：Jesper Bj?rklund, Kristina Seftigen, Markus Stoffel, Marina V. Fonti, Sven Kottlow, David C. Frank, Jan Esper, Patrick Fonti, Hugues Goosse, H?kan Grudd, Bj?rn E. Gunnarson, Daniel Nievergelt, Elena Pellizzari, Marco Carrer Georg von Arx

▲ 链接：

https://www.nature.com/articles/s41586-023-06176-4

▲ 摘要：

地球系统模子和各类天气代办署理来历注解，全球变暖最少在公元前是史无前例的。研究操纵树木年轮发现，芬诺斯坎迪亚半岛当前的天气比中世纪期间的天气要暖和很多。这凸起了即便在区域标准上，报酬逼迫在天气变暖中的主导感化，从而和谐了重建和模式摹拟之间的纷歧致。

研究者利用每一年解决1170年的树木年轮记实，该记实完全依靠在松树的管状剖解丈量，供给了暖和季候仪器温度转变的高保真丈量。

是以，他们呼吁成立更多如许的千年记实，以进一步提高对汗青和将来天气转变的熟悉，削减区域间甚至全球标准上的不肯定性。

▲ Abstract：

Earth system models and various climate proxy sources indicate global warming is unprecedented during at least the Common Era. Here we show that the current climate of the Fennoscandian Peninsula is substantially warmer than that of the medieval period. This highlights the dominant role of anthropogenic forcing in climate warming even at the regional scale, thereby reconciling inconsistencies between reconstructions and model simulations. We used an annually resolved 1,170-year-long tree-ring record that relies exclusively on tracheid anatomical measurements from Pinus sylvestris trees, providing high-fidelity measurements of instrumental temperature variability during the warm season. We therefore call for the construction of more such millennia-long records to further improve our understanding and reduce uncertainties around historical and future climate change at inter-regional and eventually global scales.

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