编译 | 李言
Science, 3 MAY 2024, Volume 384 Issue 6695
《科学》2024年5月3日，第384卷，6695期
化学Chemistry
An active, stable cubic molybdenum carbide catalyst for the high-temperature reverse water-gas shift reaction
一种用于高温逆向水煤气变换反应的活性、稳定的立方碳化钼催化剂
▲ 作者：MILAD AHMADI KHOSHOOEI, XIJUN WANG et al.
▲ 链接：
https://www.science.org/doi/10.1126/science.adl1260
▲ 摘要：
我们的研究展示了，通过简单和可扩展的途径制备的纳米晶立方碳化钼（α-Mo2C），具有100%的CO2还原为CO的选择性，同时在600度的恶劣反应条件下暴露超过500小时后，还能保持初始平衡转化。
催化剂的现场原位和事后表征结合表明，其高活性、选择性和稳定性分别归因于晶体相纯度、CO-Mo2C弱相互作用和间隙氧原子。机理研究和密度泛函理论（DFT）计算证明了反应是通过H2辅助氧化还原机制进行的。
▲ Abstract：
We show that nanocrystalline cubic molybdenum carbide (α-Mo2C), prepared through a facile and scalable route, offers 100% selectivity for CO2 reduction to CO while maintaining its initial equilibrium conversion at high space velocity after more than 500 hours of exposure to harsh reaction conditions at 600°C. The combination of operando and postreaction characterization of the catalyst revealed that its high activity, selectivity, and stability are attributable to crystallographic phase purity, weak CO-Mo2C interactions, and interstitial oxygen atoms, respectively. Mechanistic studies and density functional theory (DFT) calculations provided evidence that the reaction proceeds through an H2-aided redox mechanism.
物理学Physics
Atomic physics on a 50-nm scale: Realization of a bilayer system of dipolar atoms
50纳米尺度上的原子物理学：实现偶极原子双层系统
▲ 作者：LI DU, PIERRE BARRAL et al.
▲ 链接：
https://www.science.org/doi/10.1126/science.adh3023
▲ 摘要：
在这项研究中，我们实现了一种超分辨率技术，可以在小于50纳米的尺度上定位和排列原子，而没有任何基本的分辨率限制。
通过创建双层镝原子，并经过层间交感冷却和耦合集体激发观察两个物理分离层之间的偶极相互作用，我们得以验证这项技术。
在50纳米尺度上，偶极相互作用的强度是500纳米的1000倍。对于光镊中的两个原子，这应该能实现具有千赫兹速度的纯磁偶极门。
▲ Abstract：
In this work, we implemented a super-resolution technique that localizes and arranges atoms on a sub–50-nm scale, without any fundamental limit in resolution. We demonstrate this technique by creating a bilayer of dysprosium atoms and observing dipolar interactions between two physically separated layers through interlayer sympathetic cooling and coupled collective excitations. At 50-nm distance, dipolar interactions are 1000 times stronger than at 500 nm. For two atoms in optical tweezers, this should enable purely magnetic dipolar gates with kilohertz speed.
N-type semiconducting hydrogel
N型半导体水凝胶
▲ 作者：PEIYUN LI, WENXI SUN et al.
▲ 链接：
https://www.science.org/doi/10.1126/science.adj4397
▲ 摘要：
我们开发了基于水溶性N型半导体聚合物的单网络和多网络水凝胶，赋予传统水凝胶以半导体性能。这些水凝胶具有良好的电子迁移率和高开/关比，能够制造具有低功耗和高增益的互补逻辑电路和信号放大器。
我们证实了具有良好生物粘合剂和相容性界面的水凝胶电子元件可以感知和放大电生理信号，并提高信噪比。
▲ Abstract：
We developed single- and multiple-network hydrogels based on a water-soluble n-type semiconducting polymer, endowing conventional hydrogels with semiconducting capabilities. These hydrogels show good electron mobilities and high on/off ratios, enabling the fabrication of complementary logic circuits and signal amplifiers with low power consumption and high gains. We demonstrate that hydrogel electronics with good bioadhesive and biocompatible interface can sense and amplify electrophysiological signals with enhanced signal-to-noise ratios.
医学Medicine
Risk of meningomyelocele mediated by the common 22q11.2 deletion
常见的22q11.2缺失导致脑膜脊膜膨出风险
▲ 作者：KENG IOI VONG, SANGMOON LEE et al.
▲ 链接：
https://www.science.org/doi/10.1126/science.adl1624
▲ 摘要：
脑脊膜脊髓膨出是神经管缺陷（NTDs）最严重的形式之一，也是中枢神经系统最常见的结构性先天缺陷。我们联合了脊柱裂测序联盟来确定原因。
通过对715对父母—后代三胞胎的外显子组和基因组测序，我们发现了6例染色体22q11.2缺失的患者，这表明与一般人群相比，其风险增加了23倍。此外，对另一个22q11.2缺失序列的分析表明，脑膜脊膜膨出的NTD风险增加了12至15倍。
Crkl的缺失足以在小鼠中复制NTDs，其中外显率和表达率都因母体叶酸缺乏而加剧。因此，常见的22q11.2缺失会增加脑膜脊膜膨出的风险，补充叶酸可以部分减轻这种风险。
▲ Abstract：
Meningomyelocele is one of the most severe forms of neural tube defects (NTDs) and the most frequent structural birth defect of the central nervous system. We assembled the Spina Bifida Sequencing Consortium to identify causes. Exome and genome sequencing of 715 parent-offspring trios identified six patients with chromosomal 22q11.2 deletions, suggesting a 23-fold increased risk compared with the general population. Furthermore, analysis of a separate 22q11.2 deletion cohort suggested a 12- to 15-fold increased NTD risk of meningomyelocele. The loss of Crkl, one of several neural tube–expressed genes within the minimal deletion interval, was sufficient to replicate NTDs in mice, where both penetrance and expressivity were exacerbated by maternal folate deficiency. Thus, the common 22q11.2 deletion confers substantial meningomyelocele risk, which is partially alleviated by folate supplementation.
网络科学Network Science
Induction of social contagion for diverse outcomes in structured experiments in isolated villages
孤立村庄结构实验中不同结果的社会传染诱导
▲ 作者：EDOARDO M. AIROLDI AND NICHOLAS A. CHRISTAKIS
▲ 链接：
https://www.science.org/doi/10.1126/science.adi5147
▲ 摘要：
一些人在社会网络中占据拓扑位置，这增强了他们诱导溢出效应的有效性。我们在洪都拉斯176个孤立村庄中24702人中构建了面对面网络，并根据不同方法随机分配村庄，改变了接受22个月健康教育方法的家庭比例和选择家庭的方法（随机分配法及“熟人推荐”法）。
我们评估了117个不同的知识、态度和实践结果。“熟人推荐”法减少了达到全村特定水平所需的家庭数量。知识比行为更容易传播，溢出效应扩展到不同程度。更易被采用的结果也表现出了更大的溢出效应。根据“熟人推荐”建立的社交网络通过社会传染有效促进了全民福利的改善。
▲ Abstract：
Certain people occupy topological positions within social networks that enhance their effectiveness at inducing spillovers. We mapped face-to-face networks among 24,702 people in 176 isolated villages in Honduras and randomly assigned villages to targeting methods, varying the fraction of households receiving a 22-month health education package and the method by which households were chosen (randomly versus using the friendship-nomination algorithm). We assessed 117 diverse knowledge, attitude, and practice outcomes. Friendship-nomination targeting reduced the number of households needed to attain specified levels of village-wide uptake. Knowledge spread more readily than behavior, and spillovers extended to two degrees of separation. Outcomes that were intrinsically easier to adopt also manifested greater spillovers. Network targeting using friendship nomination effectively promotes population-wide improvements in welfare through social contagion.
大气科学Atmospheric Sciences
Locally narrow droplet size distributions are ubiquitous in stratocumulus clouds
部分狭窄的液滴尺寸分布在层积云中普遍存在
▲ 作者：NITHIN ALLWAYIN, MICHAEL L. LARSEN et al.
▲ 链接：
https://www.science.org/doi/10.1126/science.adi5550
▲ 摘要：
当前，全球气候模式（GCMs）将云中的液滴尺寸分布参数化为广泛的云平均伽马。通过使用离散层积云体积的数字全息测量，我们发现云中液滴尺寸分布在厘米尺度上更窄，与云朵的平均值完全不同。
这些局部分布倾向于形成更相似的云区域的“口袋”，每个区域的特征是尺寸分布形状被稀释到不同程度。这些观察结果为微物理过程的新建模表征开辟了道路。
▲ Abstract：
Current global climate models (GCMs) parameterize cloud droplet size distributions as broad, cloud-averaged gammas. Using digital holographic measurements of discrete stratocumulus cloud volumes, we found cloud droplet size distributions to be narrower at the centimeter scale, never resembling the cloud average. These local distributions tended to form pockets of similar-looking cloud regions, each characterized by a size distribution shape that is diluted to varying degrees. These observations open the way for new modeling representations of microphysical processes.
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