科研
科研
编译|冯维维
Science, VOLUME 385,ISSUE 6715,20 SEP 2024
《科学》第385卷，6715期，2024年9月20日
物理学Physics
Squeezing the quantum noise of a gravitational-wave detector below the standard quantum limit
将引力波探测器的量子噪声压缩到标准量子极限以下
▲ 作者：WENXUAN JIA , VICTORIA XU , KEVIN KUNS, MASAYUKI NAKANO, LISA BARSOTTI, MATTHEW EVANS, NERGIS MAVALVALA, AND MEMBERS OF THE LIGO SCIENTIFIC COLLABORATION
▲链接：
https://www.science.org/doi/10.1126/science.ado8069
▲摘要：
引力波探测器使用数公里长的干涉仪来测量时空的微小膨胀和收缩。由于量子力学的原因，这些测量的精度是有限的。理论上，利用光的压缩态可以超越量子极限，而合适的滤光腔可以在更宽的频率范围内扩展这一优势。
Jia等人测量了激光干涉引力波天文台（LIGO）升级后的压缩光和滤光腔系统的性能。研究证明，这些升级提高了探测器在宽频率范围内的灵敏度。在一个较小的范围内，它超越了量子极限。
▲ Abstract：
Gravitational wave detectors use kilometers-long interferometers to measure tiny expansions and contractions of spacetime. The precision of those measurements is limited due to quantum mechanics. Theoretically, that quantum limit could be surpassed by using squeezed states of light, and a suitable filter cavity could extend the advantage over a wide frequency range. Jia et al. measured the performance of the Laser Interferometer Gravitational-Wave Observatory (LIGO) after it was upgraded with a squeezed light and filter cavity system. The authors demonstrate that the upgrades improved the sensitivity of the detector over a wide range of frequencies. Over a smaller range, it surpassed the quantum limit.
Origin and fate of the pseudogap in the doped Hubbard model
掺杂哈伯德模型中赝隙的起源和命运
▲ 作者：FEDOR IMKOVIC IV, RICCARDO ROSSI, ANTOINE GEORGES, AND MICHEL FERRERO
▲链接：
https://www.science.org/doi/10.1126/science.ade9194
▲摘要：
尽管它很简约，哈伯德模型却能描述一些强相关物质的实例，但仍有一些在数值上难以解决的问题，将零温度和有限温度下的结果联系起来尤其棘手。
Simkovic等人使用图解蒙特卡罗计算来检查在有限温度下掺杂哈伯德模型中赝隙相的外观。发现该相与反铁磁自旋相关密切相关，并与零温度下计算的基态条纹相相连。
▲ Abstract：
Despite its simplicity, the Hubbard model may be capable of describing some instances of strongly correlated matter. However, this remains difficult to solve numerically; connecting the results at zero and finite temperatures is particularly tricky. Simkovic et al. used diagrammatic Monte Carlo calculations to examine the appearance of the pseudogap phase in the doped Hubbard model at finite temperatures. This phase was found to be closely associated with antiferromagnetic spin correlations and to connect to the ground-state stripe phase calculated at zero temperature.
化学Chemistry
Polyolefin waste to light olefins with ethylene and base-metal heterogeneous catalysts
用乙烯和贱金属非均相催化剂将废旧聚烯烃转化为轻烯烃
▲ 作者：RICHARD J. CONK, JULES F. STAHLER, JAKE X. SHI, JI YANG, NATALIE G. LEFTON, JOHN N. BRUNN, ALEXIS T. BELL, AND JOHN F. HARTWIG
▲链接：
https://www.science.org/doi/10.1126/science.adq7316
▲摘要：
原则上，将塑料分解成其原始构件是一种理想的回收策略。但在实践中，这种方法不可能用于目前使用的两种最常见的塑料——聚乙烯和聚丙烯。因为相关反应在能耗上不占优势。最近，几组研究人员表明，用合适的催化剂引入新鲜的乙烯可以将聚烯烃转化为丙烯，但用于催化的贵金属价格过高。
现在Conk等人发现，可以在这个过程中使用地球上更丰富的氧化钨和钠的组合。研究表明，氧化钨在二氧化硅上和钠在γ-氧化铝上的简单组合将聚乙烯和聚丙烯或两者的混合物转化为丙烯或丙烯和异丁烯的混合物，在320°C下产量大于90%，而不需要对起始聚烯烃进行脱氢。
▲ Abstract：
Breaking down plastic into its original building blocks is an ideal recycling strategy in principle. Unfortunately, in practice, this approach isn’t possible for the two most common plastics currently in use, polyethylene and polypropylene, because the reaction is too energetically unfavorable. Very recently, several groups of researchers showed that introducing fresh ethylene with the right catalyst can transform polyolefins into propylene, but the precious metals used for the catalysis are prohibitively expensive. Conk et al. now report that the process works using a more Earth-abundant combination of tungsten oxide and sodium. The research shows that the simple combination of tungsten oxide on silica and sodium on gamma-alumina transforms PE, PP, or a mixture of the two, including postconsumer forms of these materials, to propylene or a mixture of propylene and isobutylene in greater than 90% yield at 320°C without the need for dehydrogenation of the starting polyolefins.
Radical-mediated click-clip reactions
介导的点击反应
▲ 作者：JIANTAO ZHAO, HUACHENG YU, XINGCHEN JIN, BO QIN,SHAN MEI, JIANG-FEI XU,XI ZHANG
▲链接：
https://www.science.org/doi/10.1126/science.adn2259
▲摘要：
点击化学是指在温和条件下快速进行高转化的偶联反应，同时避免竞争途径，产生相对较少的浪费。这种技术的主要缺点是，这些有利性质背后的强大驱动力往往会阻止可逆性。
Zhao等人报道了胺和吩噻嗪之间的氧化偶联在室温下表现出类似点击的效率。然而，在近紫外照射下，产生的硫-氮键可以以相似的效率进行还原性裂解。
▲ Abstract：
Click chemistry refers to a growing class of coupling reactions that proceed rapidly to high conversion under mild conditions while avoiding competing pathways and generating relatively little waste. The main drawback to this technique is that the strong driving force underlying these favorable properties tends to prevent reversibility. Zhao et al. report an oxidative coupling between amines and phenothiazines that manifests click-like efficiency at room temperature. However, the resulting sulfur-nitrogen bond can be reductively cleaved with similar efficiency by irradiation in the near-ultraviolet range.
地球科学Geoscience
A 485-million-year history of Earth’s surface temperature
4.85亿年历史的地球表面温度
▲ 作者：EMILY J. JUDD, JESSICA E. TIERNEY, DANIEL J. LUNT, ISABEL P. MONTAEZ, BRIAN T. HUBER, SCOTT L. WING, AND PAUL J. VALDES
▲链接
https://www.science.org/doi/10.1126/science.adk3705
▲摘要：
在过去的5亿年里，动植物的进化模式对气候的演变产生了重要影响。了解这一时期全球平均地表温度（GMST）是如何变化的，对于理解这段时间内驱动气候的过程至关重要。
Judd等人提出了将代理数据与气候模拟相结合构建的过去4.85亿年的GMST记录。他们发现，全球平均地表温度在11℃到36℃的范围内变化，“表观”气候敏感性为~8℃，大约是今天的两到三倍。
▲ Abstract：
Understanding how global mean surface temperature (GMST) has varied over the past half-billion years, a time in which evolutionary patterns of flora and fauna have had such an important influence on the evolution of climate, is essential for understanding the processes driving climate over that interval. Judd et al. present a record of GMST over the past 485 million years that they constructed by combining proxy data with climate modeling. They found that GMST varied over a range from 11°C to 36°C, with an “apparent” climate sensitivity of ～8°C, about two to three times what it is today.
Atmospheric blocking slows ocean-driven melting of Greenland’s largest glacier tongue
大气阻塞减缓格陵兰岛最大冰川舌的融化
▲ 作者：REBECCA ADAM MCPHERSON, CLAUDIA WEKERLE, TORSTEN KANZOW, MONICA IONITA, FINN OLE HEUKAMP, OLE ZEISING, AND ANGELIKA HUMBERT
▲链接：
https://www.science.org/doi/10.1126/science.ado5008
▲摘要：
近年来，格陵兰岛的冰川正在加速流失。McPherson等人发现，流入海洋的79号北冰川的融化近年来有所减缓。在冰排放地点的观测显示，从2018年到2021年，冰舌以下的水温有所下降。
海洋热输送的减少归因于北欧海周围海洋环流的减缓和大西洋中间水的冷却。这种减速是由欧洲大气阻塞导致的，冷空气通过弗拉姆海峡进入北极。
▲ Abstract：
Greenland has been experiencing accelerating glacier mass loss in recent years. McPherson et al. have found that melting of the 79 North Glacier, which discharges into the ocean, has been slowed somewhat in recent years. Observations at the site of ice discharge show that from 2018 to 2021, water temperatures below the ice tongue cooled. The reduction in ocean heat transport was attributed to a slowdown in ocean circulation around the Nordic seas and a cooling of the Atlantic Intermediate Water. This slowdown was driven by European atmospheric blocking that brought in cold Arctic air through the Fram Strait.
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