科学（20230324出版）一周论文导读

　　编译 | 李言
　　Science , 24 MAR 2023, Volume 379 Issue 6638
　　《科学》 2023年3月24日，第379卷，6638期
　　天文学 Astronomy
　　Surface changes observed on a Venusian volcano during the Magellan mission
　　麦哲伦号在金星上观察到疑似火山的表面变化
　　▲ 作者：ROBERT R. HERRICK AND SCOTT HENSLEY
　　▲ 链接：
　　https://www.science.org/doi/10.1126/science.abm7735
　　▲ 摘要：
　　金星的表面地质构造时间较晚，但目前尚不清楚它是否有持续的活火山活动。从1990年到1992年，麦哲伦号使用合成孔径雷达对火星表面进行成像观测。我们检查了金星上被麦哲伦号拍摄过两三次的火山区域，确定了一个约2.2平方公里的火山喷口，它在两次雷达图像之间的8个月时间里改变了形状。
　　在第二时期的图像中可以看到从火山口向下的火山流，尽管我们不能排除它们在第一个时期是存在的，但就成像几何形状的差异来看，它们在第一个时期确实没有被发现。我们将这些解释为金星上存在持续火山活动的证据。
　　▲ Abstract：
　　Venus has a geologically young surface, but it is unknown whether it has ongoing active volcanism. From 1990 to 1992, the Magellan spacecraft imaged the planet’s surface, using synthetic aperture radar. We examined volcanic areas on Venus that were imaged two or three times by Magellan and identified an ~2.2-square-kilometer volcanic vent that changed shape in the 8-month interval between two radar images. Additional volcanic flows downhill from the vent are visible in the second-epoch images, although we cannot rule out that they were present but invisible in the first epoch because of differences in imaging geometry. We interpret these results as evidence of ongoing volcanic activity on Venus.
　　物理学 Physics
　　Visualizing the atomic-scale origin of metallic behavior in Kondo insulators
　　可视化近藤绝缘体中金属行为的原子尺度起源
　　▲ 作者：HARRIS PIRIE, ERIC MASCOT, CHRISTIAN E. MATT et al.
　　▲ 链接：
　　https://www.science.org/doi/10.1126/science.abq5375
　　▲ 摘要：
　　我们发现了在重费米子超导体URu2Si2 和拓扑近道绝缘体六硼化钐（SmB6 ）的铀位缺陷周围的纳米尺度金属传导电子坑。这些缺陷扰乱了近藤云，留下了金属母态的痕迹。
　　我们的结果表明，在SmB6 中测量到的三维量子振荡是由近藤晶格缺陷引起的，但我们不能排除其他解释。我们的成像技术可以使用重费米子探针开发原子尺度的电荷传感器。
　　▲ Abstract：
　　We discovered nanometer-scale puddles of metallic conduction electrons centered around uranium-site substitutions in the heavy-fermion compound uranium ruthenium silicide (URu2Si2 ) and around samarium-site defects in the topological Kondo insulator samarium hexaboride (SmB6 ). These defects disturbed the Kondo screening cloud, leaving behind a fingerprint of the metallic parent state. Our results suggest that the three-dimensional quantum oscillations measured in SmB6  arise from Kondo-lattice defects, although we cannot exclude other explanations. Our imaging technique could enable the development of atomic-scale charge sensors using heavy-fermion probes.
　　材料科学 Material Science
　　Ferroelectricity in layered bismuth oxide down to 1 nanometer
　　低至1纳米时，层状氧化铋仍有铁电性
　　▲ 作者：QIANQIAN YANG, JINGCONG HU, YUE-WEN FANG et al.
　　▲ 链接：
　　https://www.science.org/doi/10.1126/science.abm5134
　　▲ 摘要：
　　我们设计了一种具有氧化铋层状结构的薄膜，可以通过钐的束缚在低至1纳米时仍有稳定的铁电性。这种薄膜可以通过化学溶液沉积法生长在各种基材上。我们观察到一个厚度约为1纳米的标准铁电滞回线。
　　厚度从1纳米到4.56 纳米的薄膜拥有相对较大的剩磁极化，从每平方厘米17到50微库仑。我们用第一性原理计算验证了该结构，这也表明该材料是一种孤对驱动的铁电材料。超薄铁电薄膜的结构设计制造原子尺度电子器件方面具有很大的潜力。
　　▲ Abstract：
　　We devised a film with a layered structure of bismuth oxide that can stabilize the ferroelectric state down to 1 nanometer through samarium bondage. This film can be grown on a variety of substrates with a cost-effective chemical solution deposition. We observed a standard ferroelectric hysteresis loop down to a thickness of ~1 nanometer. The thin films with thicknesses that range from 1 to 4.56 nanometers possess a relatively large remanent polarization from 17 to 50 microcoulombs per square centimeter. We verified the structure with first-principles calculations, which also pointed to the material being a lone pair–driven ferroelectric material. The structure design of the ultrathin ferroelectric films has great potential for the manufacturing of atomic-scale electronic devices.
　　Direct synthesis and chemical vapor deposition of 2D carbide and nitride MXenes
　　二维碳化物/氮化物Mxenes直接合成和化学气相沉积
　　▲ 作者：DI WANG, CHENKUN ZHOU, ALEXANDER S. FILATOV et al.
　　▲ 链接：
　　https://www.science.org/doi/10.1126/science.add9204
　　▲ 摘要：
　　二维过渡金属碳化物和氮化物（MXenes）是一类广泛应用的材料，尤其是在能源存储领域。MXenes通常通过蚀刻层状三元化合物（MAX相）来合成。
　　通过金属和金属卤化物与石墨、甲烷或氮的反应，我们展示了一种可扩展和原子经济合成MXene的直接合成路线，包括尚未从MAX相合成的化合物。直接合成使化学气相沉积生长MXene覆盖层和复杂的球晶状形态形成，通过屈曲和释放MXene覆盖层，以暴露新的表面进行进一步反应。直接合成的MXenes具有良好的锂离子插层储能能力。
　　▲ Abstract：
　　Two-dimensional transition-metal carbides and nitrides (MXenes) are a large family of materials actively studied for various applications, especially in the field of energy storage. MXenes are commonly synthesized by etching the layered ternary compounds, called MAX phases. We demonstrate a direct synthetic route for scalable and atom-economic synthesis of MXenes, including compounds that have not been synthesized from MAX phases, by the reactions of metals and metal halides with graphite, methane, or nitrogen. The direct synthesis enables chemical vapor deposition growth of MXene carpets and complex spherulite-like morphologies that form through buckling and release of MXene carpet to expose fresh surface for further reaction. The directly synthesized MXenes showed excellent energy storage capacity for lithium-ion intercalation.
　　A silicone-based support material eliminates interfacial instabilities in 3D silicone printing
　　可以消除3D硅打印中界面不稳定性的硅基支撑材料
　　▲ 作者：SENTHILKUMAR DURAIVEL, DIMITRI LAURENT, DIDIER A. RAJON et al.
　　▲ 链接：
　　https://www.science.org/doi/10.1126/science.ade4441
　　▲ 摘要：
　　我们开发了一种可以用市售硅胶配方制成精确、准确、坚固和功能性结构的硅胶3D打印技术。为了达到这种水平，我们开发了一种由硅油乳液制成的支撑材料。
　　这种材料对硅基油墨的界面张力可以忽略不计，消除了经常导致印刷的硅酮特征变形和破裂的破坏力。应用这种方法，可以使已有的硅胶配方制造低至直径8微米的复杂结构。
　　▲ Abstract：
　　We developed a silicone 3D printing technique that produces precise, accurate, strong, and functional structures made from several commercially available silicone formulations. To achieve this level of performance, we developed a support material made from a silicone oil emulsion. This material exhibits negligible interfacial tension against silicone-based inks, eliminating the disruptive forces that often drive printed silicone features to deform and break apart. The versatility of this approach enables the use of established silicone formulations in fabricating complex structures and features as small as 8 micrometers in diameter.
　　生物学 Biology
　　Evolutionarily conserved role of oxytocin in social fear contagion in zebrafish
　　催产素在斑马鱼传染社会恐惧中的进化保守作用
　　▲ 作者：IBUKUN AKINRINADE, KYRIACOS KAREKLAS, MAGDA C. TELES et al.
　　▲ 链接：
　　https://www.science.org/doi/10.1126/science.abq5158
　　▲ 摘要：
　　情感传染是同理心最古老的形式。已知催产素可以调节哺乳动物的共情行为，通过评估催产素在斑马鱼社会恐惧传染中的作用，我们测试了情绪传染的近似机制在进化上的保守程度。
　　使用催产素和催产素受体突变体，我们的研究表明催产素对斑马鱼观察者模仿同类表现者的痛苦行为是必要和充分的。斑马鱼中与情绪传染相关的大脑区域与啮齿类动物中参与相同过程的大脑区域（如纹状体、侧隔）同源，可以接受位于视前区的催产素神经元的直接投射。
　　综上，我们的结果支持催产素作为脊椎动物基本共情行为的关键调节器的作用。
　　▲ Abstract：
　　Emotional contagion is the most ancestral form of empathy. We tested to what extent the proximate mechanisms of emotional contagion are evolutionarily conserved by assessing the role of oxytocin, known to regulate empathic behaviors in mammals, in social fear contagion in zebrafish. Using oxytocin and oxytocin receptor mutants, we show that oxytocin is both necessary and sufficient for observer zebrafish to imitate the distressed behavior of conspecific demonstrators. The brain regions associated with emotional contagion in zebrafish are homologous to those involved in the same process in rodents (e.g., striatum, lateral septum), receiving direct projections from oxytocinergic neurons located in the pre-optic area. Together, our results support an evolutionary conserved role for oxytocin as a key regulator of basic empathic behaviors across vertebrates.