科研
科研
编译｜冯维维
Science, 12 Jan 2024, Volume 383, Issue 6679
《科学》，2024年1月12日，第383卷，6679期
物理学Physics
Free-electron interaction with nonlinear optical states in microresonators
微谐振器中非线性光学态的自由电子相互作用
▲ 作者：YUJIA YANG, JAN-WILKE HENKE, ARSLAN S. RAJA, F. JASMIN KAPPERT, GUANHAO HUANG, GERMAINE AREND, ZHERU QIU, ARMIN FEIST, RUI NING WANG , AND TOBIAS J. KIPPENBERG
▲ 链接：
https://www.science.org/doi/10.1126/science.adk2489
▲ 摘要：
电子显微镜提供最小尺度的成像能力。从样品中散射出来的电子束通常是能量稳定和空间均匀的。能够调制光束以获取样本的时空信息将是非常有用的，但在技术上具有挑战性。
作者证明了微谐振器中诱导的非线性光学态可以与电子束相互作用，并将非线性光学态印在电子束上。这种相互作用为电子束的超快调制提供了途径，并拓宽了电子显微镜在时空成像和光谱学方面的应用。
▲ Abstract：
Electron microscopes provide imaging capability on the tiniest of scales. The electron beams that scatter off the samples are generally energetically stable and spatially uniform. Being able to modulate the beam to access spatiotemporal information about the sample would be extremely useful but is technically challenging. Yang et al. demonstrate that the nonlinear optical states induced in a microresonator can interact with the electron beam and imprint the nonlinear optical states onto the beam. This interaction provides access to ultrafast modulation of the electron beam and broadens the application of electron microscopes for spatiotemporal imaging and spectroscopy.
Designing metainterfaces with specified friction laws
设计具有指定摩擦律的元接口
▲ 作者：ANTOINE AYMARD, EMILIE DELPLANQUE, DAVY DALMAS, AND JULIEN SCHEIBERT
▲ 链接：
https://www.science.org/doi/10.1126/science.adk4234
▲ 摘要：
触摸屏和机械手等许多设备都涉及摩擦接触。优化这些装置需要对界面的摩擦规律进行精细控制。目前缺乏系统的方法来创建其摩擦行为满足预设规格的干接触界面。作者提出了一种通用的表面设计策略来制备具有法向力和摩擦力之间预定义关系的干粗糙界面。
这种元界面通过将简化的表面形貌视为球形凹凸体的集合，规避了摩擦学中通常的多尺度挑战。优化单个凸起的高度可以使特定的摩擦规律有针对性。
通过各种厘米尺度的弹性体—玻璃元界面，研究者描述了三种可实现的摩擦定律，包括具有特定摩擦系数的线性定律和不寻常的非线性定律。这种设计策略代表了一种不依赖于规模和材料、无化学物质的节能和适应性智能接口途径。
▲ Abstract：
Many devices, including touchscreens and robotic hands, involve frictional contacts. Optimizing these devices requires fine control of the interface’s friction law. We lack systematic methods to create dry contact interfaces whose frictional behavior satisfies preset specifications. We propose a generic surface design strategy to prepare dry rough interfaces that have predefined relationships between normal and friction forces. Such metainterfaces circumvent the usual multiscale challenge of tribology by considering simplified surface topographies as assemblies of spherical asperities. Optimizing the individual asperities’ heights enables specific friction laws to be targeted. Through various centimeter-scaled elastomer-glass metainterfaces, we illustrate three types of achievable friction laws, including linear laws with a specified friction coefficient and unusual nonlinear laws. This design strategy represents a scale- and material-independent, chemical-free pathway toward energy-saving and adaptable smart interfaces.
化学Chemistry
Synthetic dioxygenase reactivity by pairing electrochemical oxygen reduction and water oxidation
电化学氧还原与水氧化配对合成双加氧酶的反应性
▲ 作者：MD. ASMAUL HOQUE, JAMES B. GERKEN, AND SHANNON S. STAHL
▲ 链接：
https://www.science.org/doi/10.1126/science.adk5097
▲ 摘要：
分子氧的反应性对清洁能源技术和绿色化学合成至关重要，但动力学障碍使这两种应用复杂化。在合成中，双氧应能以完美的原子经济性将氧原子转移到两个有机分子上，但这种反应性很少见。
单加氧酶通常通过牺牲一个氧原子来产生更活泼的氧化剂来还原激活双氧。研究者使用锰—四苯基卟啉催化剂将电化学氧还原和水氧化配对，在两个电极上生成活性锰—氧。
这个过程支持双氧原子转移到两个硫醚底物分子上，产生两个等量的亚砜和一个等量的双氧。这种双加氧酶的净反应性不消耗电子，而是利用电化学能量来克服动力学障碍。
▲ Abstract：
The reactivity of molecular oxygen is crucial to clean energy technologies and green chemical synthesis, but kinetic barriers complicate both applications. In synthesis, dioxygen should be able to undergo oxygen atom transfer to two organic molecules with perfect atom economy, but such reactivity is rare. Monooxygenase enzymes commonly reductively activate dioxygen by sacrificing one of the oxygen atoms to generate a more reactive oxidant. Here, we used a manganese-tetraphenylporphyrin catalyst to pair electrochemical oxygen reduction and water oxidation, generating a reactive manganese-oxo at both electrodes. This process supports dioxygen atom transfer to two thioether substrate molecules, generating two equivalents of sulfoxide with a single equivalent of dioxygen. This net dioxygenase reactivity consumes no electrons but uses electrochemical energy to overcome kinetic barriers.
Twisted epitaxy of gold nanodisks grown between twisted substrate layers of molybdenum disulfide
在扭曲二硫化钼衬底层间生长的金纳米片的扭曲外延
▲ 作者：YI CUI, JINGYANG WANG, YANBIN LI, YECUN WU, EMILY BEEN, ZEWEN ZHANG, JIAWEI ZHOU, WENBO ZHANG, HAROLD Y. HWANG, AND YI CUI
▲ 链接：
https://www.science.org/doi/10.1126/science.adk5947
▲ 摘要：
晶体薄膜的外延生长通常从一个衬底开始。研究者报道了两个二硫化钼(MoS2)层都可以对金施加取向效应，他们在一个二硫化钼衬底上生长金纳米颗粒层，然后用第二层二硫化钼薄膜覆盖纳米颗粒。
加热后，纳米颗粒被压扁成纳米片。对于两个衬底之间较小的扭转角（约7度），纳米厚的金纳米片采用介于两个衬底之间的取向。这种排列的部分原因是金与硫的化学相互作用。
▲ Abstract：
Epitaxial growth of a crystalline film normally proceeds from one substrate. Cui et al. report that two molybdenum disulfide (MoS2) layers can both impose orientation effects on gold. The authors grew gold nanoparticle layers on one MoS2 substrate and then covered the nanoparticles with a second MoS2 film. Upon heating, the nanoparticles flattened to nanodisks. For small twist angles between the two substrates (about 7 degrees), the nanometer-thick gold nanodisks adopted an orientation intermediate to both substrates. This alignment was driven in part by the chemical interaction of gold with sulfur.
保护生物学Conservation biology
Comprehensive conservation assessments reveal high extinction risks across Atlantic Forest trees
大西洋森林林木灭绝风险很高
▲ 作者：RENATO A. F. DE, GILLES DAUBY, ANDRé L. DE GASPER, EDUARDO P. FERNANDEZ, ALEXANDER C. VIBRANS, ALEXANDRE A. DE OLIVEIRA, PAULO I. PRADO, VINíCIUS C. SOUZA, MARINEZ F. DE SIQUEIRA, AND HANS TER STEEGE
▲ 链接：
https://www.science.org/doi/10.1126/science.abq5099
▲ 摘要：
全球生物多样性正在下降，但许多生物多样性热点地区仍缺乏全面的物种保护评估。
研究者利用国际自然保护联盟红色名录的多种灭绝风险评估标准和数以百万计的植物标本馆和森林清查记录，对大西洋森林生物多样性热点地区的所有树种（包括约1100种迄今未评估的树种）进行了自动保护评估，约65%的物种和82%的特有物种被列为受威胁物种。
研究者重新发现了世界自然保护联盟红色名录上被列为灭绝的5种物种，并确定了13种可能灭绝的地方性物种。物种信息的不确定性对评估影响不大，但使用较少的红色名录标准严重低估了威胁水平。研究者认为，全世界热带森林的保护状况比以前报道的要差。
▲ Abstract：
Biodiversity is declining globally, yet many biodiversity hotspots still lack comprehensive species conservation assessments. Using multiple International Union for Conservation of Nature (IUCN) Red List criteria to evaluate extinction risks and millions of herbarium and forest inventory records, we present automated conservation assessments for all tree species of the Atlantic Forest biodiversity hotspot, including ~1100 heretofore unassessed species. About 65% of all species and 82% of endemic species are classified as threatened. We rediscovered five species classified as Extinct on the IUCN Red List and identified 13 endemics as possibly extinct. Uncertainties in species information had little influence on the assessments, but using fewer Red List criteria severely underestimated threat levels. We suggest that the conservation status of tropical forests worldwide is worse than previously reported.
Global shark fishing mortality still rising despite widespread regulatory change
全球鲨鱼捕捞死亡率仍在上升
▲ 作者：BORIS WORM , SARA OROFINO, ECHELLE S. BURNS, NIDHI G. D’COSTA, LEONARDO MANIR FEITOSA, MARIA L. D. PALOMARES, LAURENNE SCHILLER, AND DARCY BRADLEY
▲ 链接：
https://www.science.org/doi/10.1126/science.adf8984
▲ 摘要：
过去二十年，鲨鱼越来越被认为是世界上最受威胁的野生动物之一，受到了更严格的科学和监管审查。然而，保护条例对鲨鱼捕捞死亡率的影响尚未在全球范围内进行评估。
研究者估计，2012年至2019年期间，捕捞总死亡率从至少7600万条增加到8000万条，其中约2500万条是濒危物种。沿海水域的死亡率增加了4%，但远洋渔业的死亡率下降了7%，特别是在大西洋和西太平洋。
通过将捕捞死亡率数据与全球监管格局联系起来，研究表明，旨在防止鲨鱼鳍的广泛立法并没有降低死亡率，但区域鲨鱼捕捞或保留禁令取得了一些成功。这些分析与专家访谈相结合，强调了以证据为基础的解决方案，以扭转对鲨鱼的持续过度捕捞。
▲ Abstract：
Over the past two decades, sharks have been increasingly recognized among the world’s most threatened wildlife and hence have received heightened scientific and regulatory scrutiny. Yet, the effect of protective regulations on shark fishing mortality has not been evaluated at a global scale. Here we estimate that total fishing mortality increased from at least 76 to 80 million sharks between 2012 and 2019, ~25 million of which were threatened species. Mortality increased by 4% in coastal waters but decreased by 7% in pelagic fisheries, especially across the Atlantic and Western Pacific. By linking fishing mortality data to the global regulatory landscape, we show that widespread legislation designed to prevent shark finning did not reduce mortality but that regional shark fishing or retention bans had some success. These analyses, combined with expert interviews, highlight evidence-based solutions to reverse the continued overexploitation of sharks.
本文链接：http://www.knowith.com/news-3-27-0.html《科学》（20240112出版）一周论文导读
声明：本网页内容旨在传播知识，若有侵权等问题请及时与本网联系，我们将在第一时间删除处理。邮件：2376512515@qq.com。天上从来不会掉馅饼，请大家时刻谨防诈骗
