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发布日期：2024-07-24 作者：开云
Nature,23 May 2024, VOL 629, ISSUE 8013
《天然》2024年5月23日，第629卷，8013期
太阳发机电效应始在太阳概况四周
▲ 作者：Geoffrey M. Vasil, Daniel Lecoanet, Kyle Augustson, Keaton J. Burns, Jeffrey S. Oishi, Benjamin P. Brown, et al.
▲ 链接：
https://www.nature.com/articles/s41586-024-07315-1
▲ 摘要：
太阳磁发机电效应周期具有怪异模式：太阳黑子呈现的传布区域位在纬度30°四周，每11年在赤道四周消逝。另外，被称为改变振荡的纵向活动与太阳黑子迁徙紧密亲密相干，毫无疑问具有配合缘由。
与暗示这些现象深层发源的理论相反，日震学将低纬度改变振荡切确定位在太阳外层的5~10%，即近太阳概况剪切层。在该区域内，向内增添的差动扭转与极向磁场耦合，强烈暗示了磁扭转不不变性，这在吸积盘理论中很凸起，在尝试室中亦可不雅测。总之，这两个事实引出了一个遍及的问题：太阳发机电效应是不是源在近太阳概况的不不变性。
研究组陈述了强有力的必定证据，与存眷更深差旋层的传统模子构成光鲜对照。简单的阐发估量注解，近太阳概况磁扭转不不变性更好地注释了改变振荡的时空标准和揣度的太阳内部磁场振幅。
最早进的数值摹拟证实了这些估量，并重现了半球磁流螺旋度定律。发机电效应发生在一个被充实理解的近太阳概况现象，这有助在对影响地球电磁根本举措措施的全磁周期和空间气候进行正确猜测。
▲ Abstract：
The magnetic dynamo cycle of the Sun features a distinct pattern: a propagating region of sunspot emergence appears around 30° latitude and vanishes near the equator every 11?years. Moreover, longitudinal flows called torsional oscillations closely shadow sunspot migration, undoubtedly sharing a common cause. Contrary to theories suggesting deep origins of these phenomena, helioseismology pinpoints low-latitude torsional oscillations to the outer 5–10% of the Sun, the near-surface shear layer. Within this zone, inwardly increasing differential rotation coupled with a poloidal magnetic field strongly implicates the magneto-rotational instability, prominent in accretion-disk theory and observed in laboratory experiments. Together, these two facts prompt the general question: whether the solar dynamo is possibly a near-surface instability. Here we report strong affirmative evidence in stark contrast to traditional models focusing on the deeper tachocline. Simple analytic estimates show that the near-surface magneto-rotational instability better explains the spatiotemporal scales of the torsional oscillations and inferred subsurface magnetic field amplitudes. State-of-the-art numerical simulations corroborate these estimates and reproduce hemispherical magnetic current helicity laws. The dynamo resulting from a well-understood near-surface phenomenon improves prospects for accurate predictions of full magnetic cycles and space weather, affecting the electromagnetic infrastructure of Earth.
物理学Physics
Lithium tantalate photonic integrated circuits for volume manufacturing
可量产的钽酸锂光子集成电路
▲ 作者：Chengli Wang, Zihan Li, Johann Riemensberger, Grigory Lihachev, Mikhail Churaev, Wil Kao, et al.
▲ 链接：
https://www.nature.com/articles/s41586-024-07369-1
▲ 摘要：
基在铌酸锂（LiNbO3）的电-光光子集成电路（PICs）已被证实具有高Pockels系数材料的庞大能力。这实现了互补金属-氧化物-半导体电压程度下工作的线性和高速调制器可用在数据中间通讯、高机能计较和AI光子加快器等利用。
但是，这类手艺的工业利用遭到单片晶圆高本钱和有限晶圆尺寸的阻碍。高本钱是因为在微电子范畴的庞大投资鞭策了绝缘体上硅（SOI）光子学的采取，而在其他范畴缺少现有的高容量利用。
研究组报导了由钽酸锂（LiTaO3）制成的低消耗PIC，LiTaO3已在贸易上用在5G射频滤波器，是以可以低本钱进行可扩大的制造，而且LiTaO3具有与LiNbO3类似乃至在某些环境下更优的机能。成果注解，利用基在深紫外（DUV）步进的制造工艺，LiTaO3可被蚀刻以建立低消耗（5.6 dB m-1）PIC。
他们演示了一种LiTaO3马赫-曾德尔调制器（MZM），其半波电压-长度积为1.9 V cm，电光带宽高达40 GHz。与LiNbO3比拟，LiTaO3具有极低的双折射率，可实现所有电信频段上的高密度电路和宽带操作。另外，该平台还撑持生成孤子微梳。该工作为低本钱和多量量的下一代光电PIC的可扩大制造摊平了道路。
▲ Abstract：
Electro-optical photonic integrated circuits (PICs) based on lithium niobate (LiNbO3) have demonstrated the vast capabilities of materials with a high Pockels coefficient. They enable linear and high-speed modulators operating at complementary metal–oxide–semiconductor voltage levels to be used in applications including data-centre communications, high-performance computing and photonic accelerators for AI. However, industrial use of this technology is hindered by the high cost per wafer and the limited wafer size. The high cost results from the lack of existing high-volume applications in other domains of the sort that accelerated the adoption of silicon-on-insulator (SOI) photonics, which was driven by vast investment in microelectronics. Here we report low-loss PICs made of lithium tantalate (LiTaO3), a material that has already been adopted commercially for 5G radiofrequency filters and therefore enables scalable manufacturing at low cost, and it has equal, and in some cases superior, properties to LiNbO3. We show that LiTaO3 can be etched to create low-loss (5.6 dB m-1) PICs using a deep ultraviolet (DUV) stepper-based manufacturing process. We demonstrate a LiTaO3 Mach–Zehnder modulator (MZM) with a half-wave voltage–length product of 1.9 V cm and an electro-optic bandwidth of up to 40 GHz. In comparison with LiNbO3, LiTaO3 exhibits a much lower birefringence, enabling high-density circuits and broadband operation over all telecommunication bands. Moreover, the platform supports the generation of soliton microcombs. Our work paves the way for the scalable manufacture of low-cost and large-volume next-generation electro-optical PICs.
材料科学Materials Science
Selenium-alloyed tellurium oxide for amorphous p-channel transistors
硒合金氧化碲助力非晶p沟道晶体管
▲ 作者：Ao Liu, Yong-Sung Kim, Min Gyu Kim, Youjin Reo, Taoyu Zou, Taesu Choi, et al.
▲ 链接：
https://www.nature.com/articles/s41586-024-07360-w
▲ 摘要：
与多晶半导体比拟，非晶半导体供给了固有本钱效益，易在加工和同一制造。传统的非晶氢化硅在电机能方面存在不足，亟需开辟新材料。
高迁徙率非晶n型金属氧化物（如a-InGaZnO）的发生和其与薄膜晶体管（TFTs）的集成，鞭策了现代年夜面积电子器件和新一代显示器的前进。但是，寻觅近似的p型对应物颇具挑战，阻碍了互补金属-氧化物-半导体手艺和集成电路的进展。
研究组介绍了一种非晶p型半导体的首创性设计谋略，将高迁徙率碲引入至非晶亚氧化碲基体，并展现了其在高机能、不变的p沟道TFTs和互补电路中的利用。理论阐发揭露了具有浅受主态的碲5p带的离域价带，可实现过量的空穴开云体育app搀杂和输运。
硒合金化按捺了空穴浓度，增进了p轨道的毗连，实现了高机能的p沟道TFTs，其平均场效应空穴迁徙率约为15 cm2 V-1 s-1，开/关电流比为106~107，且在偏置应力和情况老化下具有晶圆级平均性和持久不变性。这项研究代表了以低本钱和工业兼容的体例成立贸易上可行的非晶p沟道TFT手艺和互补电子装备的要害一步。
▲ Abstract：
Compared to polycrystalline semiconductors, amorphous semiconductors offer inherent cost-effective, simple and uniform manufacturing. Traditional amorphous hydrogenated Si falls short in electrical properties, necessitating the exploration of new materials. The creation of high-mobility amorphous n-type metal oxides, such as a-InGaZnO, and their integration into thin-film transistors (TFTs) have propelled advancements in modern large-area electronics and new-generation displays. However, finding comparable p-type counterparts poses notable challenges, impeding the progress of complementary metal–oxide–semiconductor technology and integrated circuits. Here we introduce a pioneering design strategy for amorphous p-type semiconductors, incorporating high-mobility tellurium within an amorphous tellurium suboxide matrix, and demonstrate its use in high-performance, stable p-channel TFTs and complementary circuits. Theoretical analysis unveils a delocalized valence band from tellurium 5p bands with shallow acceptor states, enabling excess hole doping and transport. Selenium alloying suppresses hole concentrations and facilitates the p-orbital connectivity, realizing high-performance p-channel TFTs with an average field-effect hole mobility of around 15?ccm2 V-1 s-1 and on/off current ratios of 106~107, along with wafer-scale uniformity and long-term stabilities under bias stress and ambient ageing. This study represents a crucial stride towards establishing commercially viable amorphous p-channel TFT technology and complementary electronics in a low-cost and industry-compatible manner.
电子工程Electronic Engineering
Full-colour 3D holographic augmented-reality displays with metasurface waveguides
具有超概况波导的全彩3D全息加强实际显示器
▲ 作者：Manu Gopakumar, Gun-Yeal Lee, Suyeon Choi, Brian Chao, Yifan Peng, Jonghyun Kim, et al.
▲ 链接：
https://www.nature.com/articles/s41586-024-07386-0
▲ 摘要：
新兴空间计较系统将数字信息无缝叠加在用户不雅察到的物理情况上，从而实现了文娱、教育、通讯和培训等各个范畴的变化性体验。但是，因为加强实际（AR）显示器的光引擎投影光学元件体积重大，且没法正确描画虚拟内容的三维（3D）深度旌旗灯号等身分，其普遍采取遭到限制。
研究组介绍了一种全息AR系统，利用反向设计的全彩色B超概况光栅、紧凑的色散抵偿波导几何布局和人工智能驱动的全息算法的怪异组合来降服这些挑战。这些元件是协同设计的，消弭了空间光调制器和波导之间对重大准直光学器件的需求，并以紧凑装备规格来显现活泼的全彩3D AR内容。
为了经由过程该原型供给史无前例的视觉质量，研究组开辟了一种融会物理切确的波导模子与相机反馈主动校准的进修组件的立异图象构成模子。这类怪异的纳米光子超概况波导和人工智能驱动全息算法的结合设计代表了在紧凑可穿着装备中建立视觉上惹人注视的3D AR体验的重猛进步。
▲ Abstract：
Emerging spatial computing systems seamlessly superimpose digital information on the physical environment observed by a user, enabling transformative experiences across various domains, such as entertainment, education, communication and training. However, the widespread adoption of augmented-reality (AR) displays has been limited due to the bulky projection optics of their light engines and their inability to accurately portray three-dimensional (3D) depth cues for virtual content, among other factors. Here we introduce a holographic AR system that overcomes these challenges using a unique combination of inverse-designed full-colour metasurface gratings, a compact dispersion-compensating waveguide geometry and artificial-intelligence-driven holography algorithms. These elements are co-designed to eliminate the need for bulky collimation optics between the spatial light modulator and the waveguide and to present vibrant, full-colour, 3D AR content in a compact device form factor. To deliver unprecedented visual quality with our prototype, we develop an innovative image formation model that combines a physically accurate waveguide model with learned components that are automatically calibrated using camera feedback. Our unique co-design of a nanophotonic metasurface waveguide and artificial-intelligence-driven holographic algorithms represents a significant advancement in creating visually compelling 3D AR experiences in a compact wearable device.
化学Chemistry
Observation of a promethium complex in solution
溶液中钷共同物的不雅测
▲ 作者：Darren M. Driscoll, Frankie D. White, Subhamay Pramanik, Jeffrey D. Einkauf, Bruce Ravel, Dmytro Bykov, et al.
▲ 链接：
https://www.nature.com/articles/s41586-024-07267-6
▲ 摘要：
镧系稀土金属在现代手艺中遍及存在，但人们对第61号元素钷（Pm）的化学性质知之甚少，Pm是一种高度放射性且难以接近的镧系元素。虽然Pm很主要，但其在镧系元素的尝试研究中罕有触及，阻碍了人们对所谓镧系元素缩短现象的周全理解：这是通用化学教科书中援用元素周期表的一个根基方面。
研究组证实了经由过程新合成的有机二甘醇酰胺配体在水溶液中可与147Pm放射性核素（半衰期为2.62年）不变螯合。操纵同步X射线接收光谱和量子化学计较，研究了所获得的均配型PmIII共同物，肯定了钷的配位布局和键距。这些根基看法令人们可以或许对一整套同构镧系元素共同物进行完全的布局研究，终究仅在尝试不雅察的根本上捕捉溶液中的镧系缩短。
研究成果注解，在镧系元素系列最先时键缩短加快，这与二甘醇酰胺显示的分手趋向有关。在水情况中对放射性PmIII共同物的表征加深了人们对镧系元素内部行动和f区元素化学和分手的理解。
▲ Abstract：
Lanthanide rare-earth metals are ubiquitous in modern technologies, but we know little about chemistry of the 61st element, promethium (Pm), a lanthanide that is highly radioactive and inaccessible. Despite its importance, Pm has been conspicuously absent from the experimental studies of lanthanides, impeding our full comprehension of the so-called lanthanide contraction phenomenon: a fundamental aspect of the periodic table that is quoted in general chemistry textbooks. Here we demonstrate a stable chelation of the 147Pm radionuclide (half-life of 2.62 years) in aqueous solution by the newly synthesized organic diglycolamide ligand. The resulting homoleptic PmIII complex is studied using synchrotron X-ray absorption spectroscopy and quantum chemical calculations to establish the coordination structure and a bond distance of promethium. These fundamental insights allow a complete structural investigation of a full set of isostructural lanthanide complexes, ultimately capturing the lanthanide contraction in solution solely on the basis of experimental observations. Our results show accelerated shortening of bonds at the beginning of the lanthanide series, which can be correlated to the separation trends shown by diglycolamides. The characterization of the radioactive PmIII complex in an aqueous environment deepens our understanding of intra-lanthanide behaviour and the chemistry and separation of the f-block elements.
Boron catalysis in a designer enzyme
人工酶中的硼催化感化
▲ 作者：Lars Longwitz, Reuben B. Leveson-Gower, Henri?tte J. Rozeboom, Andy-Mark W. H. Thunnissen Gerard Roelfes
▲ 链接：
https://www.nature.com/articles/s41586-024-07391-3
▲ 摘要：
酶在提高化工出产的友爱性和效力方面阐扬着愈来愈主要的感化，但因为酶的反映机理规模相对狭小，其利用的多样性严重掉队在化学催化剂。含有非生物功能酶的缔造增进了天然界经典以外的反映机制，并为完全可编程的生物催化摊平了道路。
研究组提出了一种完全遗传编码的含硼酸的人工酶，其有机催化活性是自然或工程生物催化剂没法实现的。这类硼酶经由过程肟构成催化羟基酮的动力学拆分，此中与卵白质支架的要害彼此感化有助在催化。定向进化活动致使了对几种分歧底物具有自然酶样对映体选择性的变体。
操纵X射线晶体学、高分辩率质谱（HRMS）和11B NMR波谱证实了硼酶的怪异活化模式。研究成果注解，遗传暗码扩大可用在建立可进化的对映选择性酶，这些酶依靠在外源性催化部门，如硼酸和经由过程自然某人工酶的催化稠浊性没法到达的通路反映机制。
▲ Abstract：
Enzymes play an increasingly important role in improving the benignity and efficiency of chemical production, yet the diversity of their applications lags heavily behind chemical catalysts as a result of the relatively narrow range of reaction mechanisms of enzymes. The creation of enzymes containing non-biological functionalities facilitates reaction mechanisms outside nature’s canon and paves the way towards fully programmable biocatalysis. Here we present a completely genetically encoded boronic-acid-containing designer enzyme with organocatalytic reactivity not achievable with natural or engineered biocatalysts. This boron enzyme catalyses the kinetic resolution of hydroxyketones by oxime formation, in which crucial interactions with the protein scaffold assist in the catalysis. A directed evolution campaign led to a variant with natural-enzyme-like enantioselectivities for several different substrates. The unique activation mode of the boron enzyme was confirmed using X-ray crystallography, high-resolution mass spectrometry (HRMS) and 11B NMR spectroscopy. Our study demonstrates that genetic-code expansion can be used to create evolvable enantioselective enzymes that rely on xenobiotic catalytic moieties such as boronic acids and access reaction mechanisms not reachable through catalytic promiscuity of natural or engineered enzymes.
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