作者:未玖 来源:科学网微信公众号 发布时间:2023/11/19 20:49:32
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《科学》(20231117出版)一周论文导读

 

Science, 17 NOV 2023, VOL 382, ISSUE 6672

《科学》2023年11月17日,第382卷,6672期

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物理学Physics

High cooling performance in a double-loop electrocaloric heat pump

双回路电热性热泵的高制冷性能

▲ 作者:Junning Li, Alvar Torelló, Veronika Kovacova, Uros Prah, Ashwath Aravindhan, Torsten Granzow, et al.

▲ 链接:https://www.science.org/doi/full/10.1126/science.adi5477

▲ 摘要:

通过固态电热材料冷却是蒸气压缩的一种有吸引力的替代品。尽管人们做出了很多努力,但目前仍未开发出具有潜在商业竞争力的设备。

研究组提出了一种电热冷却器,在10伏特/微米的中等外加电场下,最大温差范围为20.9 K,最大冷却功率为4.2瓦,且未观察到任何击穿。此外,即使考虑到流体泵送所消耗的能量,只要能量得到适当回收,最大性能系数也能达到卡诺效率的64%。

研究组认为,电热冷却是一种非常有前景的蒸汽压缩冷却替代方案。

▲ Abstract:

Cooling through solid-state electrocaloric materials is an attractive replacement for vapor compression. Despite recent efforts, devices that are potentially commercially competitive have not been developed. We present an electrocaloric cooler with a maximum temperature span of 20.9 kelvin and a maximum cooling power of 4.2 watts under the moderate applied electric field of 10 volts per micrometer without any observed breakdown. Moreover, the maximum coefficient of performance, even taking into account energy expended on fluid pumping, reaches 64% of Carnot’s efficiency as long as energy is properly recovered. We believe that this demonstration shows electrocaloric cooling to be a very promising alternative to vapor compression cooling.

材料科学Materials Science

An all-metal fullerene: [K@Au12Sb20]5−

全金属富勒烯:[K@Au12Sb20]5−

▲ 作者:Yu-He Xu, Wen-Juan Tian, Alvaro Muñoz-Castro, Gernot Frenking & Zhong-Ming Sun

▲ 链接:https://www.science.org/doi/full/10.1126/science.adj6491

▲ 摘要:

C60富勒烯分子以其独特的近球形结构引起了人们极大的兴趣。相比之下,全金属的类似物一直难以捉摸:由非碳元素组成的类富勒烯团簇通常不稳定,导致更紧凑的几何形状,需要多个嵌入原子或外部配体来稳定。

在这项工作中,研究组提出用湿化学方法合成全金属富勒烯簇[K@Au12Sb20]5−。通过单晶X射线衍射确定了该团簇的结构,揭示了一个由20个锑原子组成的富勒烯框架。理论计算进一步表明,这种独特的团簇表现出芳香行为。

▲ Abstract:

The C60 fullerene molecule has attracted tremendous interest for its distinctive nearly spherical structure. By contrast, all-metal counterparts have been elusive: Fullerene-like clusters composed of noncarbon elements typically suffer from instability, resulting in more compact geometries that require multiple embedded atoms or external ligands for stabilization. In this work, we present the synthesis of an all-metal fullerene cluster, [K@Au12Sb20]5−, using a wet-chemistry method. The clusters structure was determined by single crystal x-ray diffraction, which revealed a fullerene framework consisting of 20 antimony atoms. Theoretical calculations further indicate that this distinct cluster exhibits aromatic behavior.

化学Chemistry

Particle-phase accretion forms dimer esters in pinene secondary organic aerosol

颗粒相吸积在蒎烯二次有机气溶胶中形成二聚酯

▲ 作者:Christopher M. Kenseth, Nicholas J. Hafeman, Samir P. Rezgui, Jing Chen, Yuanlong Huang, Nathan F. Dalleska, et al.

▲ 链接:https://www.science.org/doi/full/10.1126/science.adi0857

▲ 摘要:

二次有机气溶胶(SOA)在大气中普遍存在,在气候、空气质量和健康中发挥着关键作用。通过吸积反应产生低挥发性二聚体化合物是SOA形成的一个关键方面。然而,尽管人们进行了广泛研究,但SOA中二聚体的结构及其形成机制在很大程度上仍不清楚。

在这项工作中,研究组通过独立合成真实标准物,阐明了SOA中几种主要二聚酯的结构,这些二聚酯来自α-蒎烯和β-蒎烯(全球SOA的重要来源)的臭氧分解。结果证明这些二聚酯是在颗粒相中形成的,并提出了一种醇亲核加成至环状酰基过氧半缩醛的机制。

该化学机制有望代表在环境SOA中生成二聚体化合物的通用途径。

▲ Abstract:

Secondary organic aerosol (SOA) is ubiquitous in the atmosphere and plays a pivotal role in climate, air quality, and health. The production of low-volatility dimeric compounds through accretion reactions is a key aspect of SOA formation. However, despite extensive study, the structures and thus the formation mechanisms of dimers in SOA remain largely uncharacterized. In this work, we elucidate the structures of several major dimer esters in SOA from ozonolysis of α-pinene and β-pinene—substantial global SOA sources—through independent synthesis of authentic standards. We show that these dimer esters are formed in the particle phase and propose a mechanism of nucleophilic addition of alcohols to a cyclic acylperoxyhemiacetal. This chemistry likely represents a general pathway to dimeric compounds in ambient SOA.

Nickel-catalyzed ester carbonylation promoted by imidazole-derived carbenes and salts

咪唑衍生卡宾及其盐助力镍催化的酯羰化反应

▲ 作者::Changho Yoo, Shrabanti Bhattacharya, Xin Yi See, Drew W. Cunningham, Sebastian Acosta-Calle, Steven T. Perri, et al.

▲ 链接:https://www.science.org/doi/full/10.1126/science.ade3179

▲ 摘要:

目前全球每年生产数百万吨乙酰衍生物,如乙酸和醋酸酐。这些化工组成成分被加工成酯类、酰胺类,并最终制成高分子材料、药品和其他消费品。工业上大多数乙酰基使用均相贵金属催化剂生产,主要是铑和铱配合物。

研究组报道,丰富的镍可与咪唑衍生卡宾或相应的盐配对以催化甲酯羰基化,其周转频率(TOF)超过150 h-1,周转数(TON)超过1600,该基准可与最先进的铑基体系相媲美,且大大超过已知的三苯基膦基镍催化剂,其在相同条件下TOF为7h-1,TON为100。

▲ Abstract:

Millions of tons of acetyl derivatives such as acetic acid and acetic anhydride are produced each year. These building blocks of chemical industry are elaborated into esters, amides, and eventually polymer materials, pharmaceuticals, and other consumer products. Most acetyls are produced industrially using homogeneous precious metal catalysts, principally rhodium and iridium complexes. We report here that abundant nickel can be paired with imidazole-derived carbenes or the corresponding salts to catalyze methyl ester carbonylation with turnover frequency (TOF) exceeding 150 hour–1 and turnover number (TON) exceeding 1600, benchmarks that invite comparisons to state-of-the-art rhodium-based systems and considerably surpass known triphenylphosphine-based nickel catalysts, which operate with TOF ~7 hour–1 and TON ~100 under the same conditions.

地球科学Earth Science

Curbing global solid waste emissions toward net-zero warming futures

遏制全球固体废物排放,实现净零变暖的未来

▲ 作者:Zheng Xuan Hoy, Kok Sin Woon, Wen Cheong Chin, Yee Van Fan & Seung Jick Yoo

▲ 链接:https://www.science.org/doi/full/10.1126/science.adg3177

▲ 摘要:

通过改善固体废物管理可减缓的全球升温程度,以及这在多大程度上有助于实现《巴黎协定》1.5℃和2℃减排路径目标或全球甲烷承诺的条款,目前尚无全球分析。

据研究组估计,到2050年,全球固体废物产生量将达到25.6至33.3亿吨,陡然实施技术和行为改变可能会导致相对于2020年的净零变暖固体废物系统,从而导致110至270亿吨二氧化碳升温(相当于温度限制下的排放量)。然而,这些改变需在9至17年内(2033至2041年)加速采用,以符合全球甲烷承诺。

迅速减少甲烷、二氧化碳和一氧化二氮的排放对于最大化短期气候效益和阻止持续升温是必要的。

▲ Abstract:

No global analysis has considered the warming that could be averted through improved solid waste management and how much that could contribute to meeting the Paris Agreement’s 1.5° and 2°C pathway goals or the terms of the Global Methane Pledge. With our estimated global solid waste generation of 2.56 to 3.33 billion tonnes by 2050, implementing abrupt technical and behavioral changes could result in a net-zero warming solid waste system relative to 2020, leading to 11 to 27 billion tonnes of carbon dioxide warming–equivalent emissions under the temperature limits. These changes, however, require accelerated adoption within 9 to 17 years (by 2033 to 2041) to align with the Global Methane Pledge. Rapidly reducing methane, carbon dioxide, and nitrous oxide emissions is necessary to maximize the short-term climate benefits and stop the ongoing temperature rise.

Surface climate signals transmitted rapidly to deep North Atlantic throughout last millennium

过去一千年中,地表气候迹象迅速传输到北大西洋深处

▲ 作者:Wanyi Lu, Delia W. Oppo, Geoffrey Gebbie & David J. R. Thornalley

▲ 链接:https://www.science.org/doi/full/10.1126/science.adf1646

▲ 摘要:

对地下海洋变暖的仪器观测表明,海洋热吸收减缓了20世纪的地表变暖。研究组提供了来自北大西洋副极地沉积物的高分辨率记录,这些记录与地表和深层变暖/变冷的仪器观测结果一致,此外还重建了过去1200年的地表—深层关系。

约1300米及更深的地点表明,从中世纪气候异常到小冰期的转变始于约1350±50普遍纪元(CE),温度下降了约0.5℃,而地表记录表明,非同步冷却开始的时间跨度约为600年。

这些数据表明,海洋环流整合了由大西洋经向海洋环流迅速传递到深处的地表变率,这意味着海洋在过去千年中和今天一样调节了地表温度。

▲ Abstract:

Instrumental observations of subsurface ocean warming imply that ocean heat uptake has slowed 20th-century surface warming. We present high-resolution records from subpolar North Atlantic sediments that are consistent with instrumental observations of surface and deep warming/freshening and in addition reconstruct the surface-deep relation of the last 1200 years. Sites from ~1300 meters and deeper suggest an ~0.5 degrees celsius cooling across the Medieval Climate Anomaly to Little Ice Age transition that began ~1350 ± 50 common era (CE), whereas surface records suggest asynchronous cooling onset spanning ~600 years. These data suggest that ocean circulation integrates surface variability that is transmitted rapidly to depth by the Atlantic Meridional Ocean Circulation, implying that the ocean moderated Earth’s surface temperature throughout the last millennium as it does today.

 
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