您好，欢迎访问开云网站！
您好，欢迎访问开云网站！
集团动态
联系开云
发布日期：2024-08-17 作者：开云
Nature, 8 August 2024, Volume 632 Issue 8024
《天然》2024年8月8日，第632卷，8024期
物理学Physics
Antiferromagnetic phase transition in a 3D fermionic Hubbard model
三维费米子哈伯德模子中的反铁磁相变
▲ 作者：Hou-Ji Shao, Yu-Xuan Wang et al.
▲链接：
https://www.nature.com/articles/s41586-024-07689-2
▲摘要：
费米子哈伯德模子（FHM）描写了由强电子—电子相干性引发的普遍的物理现象，包罗很是规超导的猜测机制。在此，我们陈述了一个由锂-6原子构成的三维费米子哈伯德系统的反铁磁相变的不雅察，该系统在一个平均的光学晶格中有年夜约80万个位点。当彼此感化强度、温度和搀杂浓度被微调到接近各自的临界值时，我们不雅察到自旋布局因子急剧增添。
这些不雅察成果可以用幂律发散来注释，从海森堡普适性类来看，其临界指数为1.396。在半填充和最好彼此感化强度下，测得的自旋布局因子到达123(8)，注解了反铁磁相的成立。我们的研究成果为摸索FHM的低温相图供给了机遇。
▲ Abstract：
The fermionic Hubbard model (FHM) describes a wide range of physical phenomena resulting from strong electron–electron correlations, including conjectured mechanisms for unconventional superconductivity. Here we report the observation of the antiferromagnetic phase transition in a three-dimensional fermionic Hubbard system comprising lithium-6 atoms in a uniform optical lattice with approximately 800,000 sites. When the interaction strength, temperature and doping concentration are finely tuned to approach their respective critical values, a sharp increase in the spin structure factor is observed. These observations can be well described by a power-law divergence, with a critical exponent of 1.396 from the Heisenberg universality class. At half-filling and with optimal interaction strength, the measured spin structure factor reaches 123(8), signifying the establishment of an antiferromagnetic phase. Our results provide opportunities for exploring the low-temperature phase diagram of the FHM.
材料科学Materials Science
Water- and heat-activated dynamic passivation for perovskite photovoltaics
钙钛矿光伏电池的水活化和热活化动态钝化
▲ 作者：Wei-Ting Wang, Philippe Holzhey et al.
▲链接：
https://www.nature.com/articles/s41586-024-07705-5
▲摘要：
在此，我们陈述了一种利用阻碍脲/硫代氨基甲酸酯键Lewis酸碱材料（HUBLA）的活性钝化策略，此中具有水和热活化特征的动态共价键可以动态修复钙钛矿，以确保装备的机能和不变性。表露在湿气或高温下，HUBLA会发生新的试剂，并进一步钝化钙钛矿中的缺点。
这类钝化策略实现了功率转换效力（PCE）为25.1%的高机能器件。HUBLA装备在85摄氏度的氮气中老化约1500小时后，其初始PCE连结在94%，在85摄氏度和30%相对湿度的空气中老化1000小时后，其初始PCE连结在88%。
▲ Abstract：
Here we report a living passivation strategy using a hindered urea/thiocarbamate bond Lewis acid–base material (HUBLA), where dynamic covalent bonds with water and heat-activated characteristics can dynamically heal the perovskite to ensure device performance and stability. Upon exposure to moisture or heat, HUBLA generates new agents and further passivates defects in the perovskite. This passivation strategy achieved high-performance devices with a power conversion efficiency (PCE) of 25.1 per cent. HUBLA devices retained 94 per cent of their initial PCE for approximately 1,500 hours of ageing at 85 degrees Celsius in nitrogen and maintained 88 per cent of their initial PCE after 1,000 hours of ageing at 85 degrees Celsius and 30 per cent relative humidity in air.
peri-Fused polyaromatic molecular contacts for perovskite solar cells
钙钛矿太阳能电池的聚芳族份子接触
▲ 作者：Ke Zhao, Qingqing Liu et al.
▲链接：
https://www.nature.com/articles/s41586-024-07712-6
▲摘要：
在此，我们陈述了一种没有杂原子代替的环抱稠合多环芳烃焦点布局，它比传统的杂原子代替焦点布局具有更好的载流子传输和选择性。
这类焦点布局发生了相对化学惰性和布局刚性的份子接触，可以年夜年夜提高钙钛矿太阳能电池在效力和耐用性方面的机能。在分歧的加快老化测试中，装配的效力高达26.1%，年夜年夜提高了利用寿命。
▲ Abstract：
Here we report a peri-fused polyaromatic core structure without heteroatom substitution that yields superior carrier transport and selectivity over conventional heteroatom-substituted core structures. This core structure produced a relatively chemically inert and structurally rigid molecular contact, which considerably improved the performance of perovskite solar cells in terms of both efficiency and durability. The champion device showed an efficiency up to 26.1% with greatly improved longevity under different accelerated-ageing tests.
化学Chemistry
Hydroamination of alkenes with dinitrogen and titanium polyhydrides
烯烃与二氮和钛多氢化物的氢胺化反映
▲ 作者：Takanori Shima, Qingde Zhuo et al.
▲链接：
https://www.nature.com/articles/s41586-024-07694-5
▲摘要：
在此，我们陈述在氢化氚骨架下，简单烯烃与N2的氢胺化反映，这激活了烯烃和N2，致使选择性的C-N键构成，并供给响应的烷基胺进一步氢化和质子化。
计较研究揭露了N2活化和选择性C-N键构成的要害机制细节。这项研究证实了一种经由过程多核氢化物框架，将N2和简单烃转化为含氮有机化合物的策略。
▲ Abstract：
Here we report the hydroamination of simple alkenes with N2 in a trititanium hydride framework, which activates both alkenes and N2, leading to selective C–N bond formation and providing the corresponding alkyl amines on further hydrogenation and protonation. Computational studies reveal key mechanistic details of N2 activation and selective C–N bond formation. This work demonstrates a strategy for the transformation of N2 and simple hydrocarbons into nitrogen-containing organic compounds mediated by a multinuclear hydride framework.
地球科学 Earth Science
Highest ocean heat开云体育app in four centuries places Great Barrier Reef in danger
四个世纪以来最高的海洋温度使年夜堡礁处在危险当中
▲ 作者：Benjamin J. Henley, Helen V. McGregor et al.
▲链接：
https://www.nature.com/articles/s41586-024-07672-x
▲摘要：
在此，我们注解在2024年、2017年和2020年（按平均海温异常降序摆列）1月至3月的珊瑚海极端高温是400年来最暖和的，跨越了我们重建的1900年前最年夜值的95个百分位不肯定性极限。
2016年、2004年和2022年的高温排名第二，跨越了第90个百分位数的限制。天气模式阐发证实，人类对天气系统的影响是近几十年来快速变暖的缘由。这一归因，加上比来的海洋极端温度、1900年后的变暖趋向和不雅测到的年夜范围珊瑚白化，注解报酬天气转变对年夜堡礁生态系统的保存要挟此刻已构成。
假如不采纳告急干涉干与办法，标记性的年夜堡礁将面对气温升高的风险，这将致使近乎每一年的珊瑚白化，对生物多样性和生态系统发生负面影响。假如依照今朝的轨迹继续下去，将进一步要挟到地球上最伟年夜的天然奇不雅之一的生态功能和凸起的遍及价值。
▲ Abstract：
Here we show that the January–March Coral Sea heat extremes in 2024, 2017 and 2020 (in order of descending mean SST anomalies) were the warmest in 400 years, exceeding the 95th-percentile uncertainty limit of our reconstructed pre-1900 maximum. The 2016, 2004 and 2022 events were the next warmest, exceeding the 90th-percentile limit. Climate model analysis confirms that human influence on the climate system is responsible for the rapid warming in recent decades. This attribution, together with the recent ocean temperature extremes, post-1900 warming trend and observed mass coral bleaching, shows that the existential threat to the GBR ecosystem from anthropogenic climate change is now realized. Without urgent intervention, the iconic GBR is at risk of experiencing temperatures conducive to near-annual coral bleaching, with negative consequences for biodiversity and ecosystems services. A continuation on the current trajectory would further threaten the ecological function and outstanding universal value of one of Earth’s greatest natural wonders.
Cenozoic history of the tropical marine biodiversity hotspot
热带海洋生物多样性热门地域的新生代汗青
▲ 作者：Skye Yunshu Tian, Moriaki Yasuhara et al.
▲链接：
https://www.nature.com/articles/s41586-024-07617-4
▲摘要：
地球上海洋生物多样性最高的地域被称为珊瑚三角或印澳群岛（IAA）。在此，我们操纵一个周全的化石数据集，经由过程揣度物种灭尽动态，对IAA的新生代的多样性汗青进行了高分辩率的重建。
我们发现，自2500万年前以来，IAA显现出单向多样化的趋向，年夜致呈对数增加，直到年夜约260万年前最先呈现多样性不变期。
1390万年前今后，生物多样性的增加首要受生物多样性依靠和生境巨细的节制，热应力的减缓也增进了生物多样性的增加。分歧的净多样化岑岭记实在年夜约2500万年前、2000万年前、1600万年前、1200万年前和500万年前，这可能与首要的组织事务和天气转变有关。
要害的生物地舆进程对IAA的多样性发生了深远的影响，表示在Tethyan后裔的持久式微和世界性和IAA分类群的持久繁华。最后，没有年夜灭尽和新生代冷却仿佛是使IAA成为地球上海洋生物多样性最丰硕的热门的要害。
▲ Abstract：
The region with the highest marine biodiversity on our planet is known as the Coral Triangle or Indo-Australian Archipelago (IAA). Here we present a high-resolution reconstruction of the Cenozoic diversity history of the IAA by inferring speciation–extinction dynamics using a comprehensive fossil dataset. We found that the IAA has exhibited a unidirectional diversification trend since about 25 million years ago, following a roughly logistic increase until a diversity plateau beginning about 2.6 million years ago. The growth of diversity was primarily controlled by diversity dependency and habitat size, and also facilitated by the alleviation of thermal stress after 13.9 million years ago. Distinct net diversification peaks were recorded at about 25, 20, 16, 12 and 5 million years ago, which were probably related to major tectonic events in addition to climate transitions. Key biogeographic processes had far-reaching effects on the IAA diversity as shown by the long-term waning of the Tethyan descendants versus the waxing of cosmopolitan and IAA taxa. Finally, it seems that the absence of major extinctions and the Cenozoic cooling have been essential in making the IAA the richest marine biodiversity hotspot on Earth.
特殊声明：本文转载仅仅是出在传布信息的需要，其实不意味着代表本网站不雅点或证实其内容的真实性；如其他媒体、网站或小我从本网站转载利用，须保存本网站注明的“来历”，并自大版权等法令责任；作者假如不但愿被转载或联系转载稿费等事宜，请与我们联系。