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发布日期：2024-07-03 作者：开博
Science, 3 MAY 2024, Volume 384Issue 6695
《科学》2024年5月3日，第384卷，6695期
Anactive, stable cubic molybdenum carbide catalyst for the high-temperature reverse water-gas shift reaction
一种用在高温逆向水煤气变换反映的活性、不变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：
我们的研究展现了，经由过程简单和可扩大的路子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度的卑劣反映前提下表露跨越500小时后，还能连结初始均衡转化。
催化剂的现场原位和过后表征连系注解，其高活性、选择性和不变性别离归因在晶体相纯度、CO-Mo2C弱彼此感化和间隙氧原子。机理研究和密度泛函理论（DFT）计较证实了反映是经由过程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 CO2reduction 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 anH2-aided redox mechanism.
Atomic physics on a 50-nm scale: Realization of a bilayer system of dipolar atoms
50纳米标准上的原子物理学：实现偶极原子双层系统
▲摘要：
在这项研究中，我们实现了一种超分辩率手艺，可以在小在50纳米的标准上定位和摆列原子，而没有任何根基的分辩率限制。
经由过程建立双层镝原子，并颠末层间交感冷却和耦合集体激起不雅察两个物理分手层之间的偶极彼此感化，我们得以验证这项手艺。
在50纳米标准上，偶极彼此感化的强度是500纳米的1000倍。对光镊中的两个原子，这应当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.
▲摘要：
我们开辟了基在水溶性N型半导体聚合物的单收集和多收集水凝胶，付与传统水凝胶以半导体机能。这些水凝胶具有杰出的电子迁徙率和高开/关比，可以或许制造具有低功耗和高增益的互补逻辑电路和旌旗灯号放年夜器。
我们证实了具有杰出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年夜电心理旌旗灯号，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 lo开博体育gic 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.
Risk of meningomyelocele mediated by the common 22q11.2 deletion
常见的22q11.2缺掉致使脑膜脊膜膨出风险
▲摘要：
脑脊膜脊髓膨出是神经管缺点（NTDs）最严重的情势之一，也是中枢神经系统最多见的布局性先天缺点。我们结合了脊柱裂测序同盟来肯定缘由。
经由过程对715对怙恃—儿女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缺掉的患者，这注解与常人群比拟，其风险增添了23倍。另外，对另外一个22q11.2缺掉序列的阐发注解，脑膜脊膜膨出的NTD风险增添了12至15倍。
Crkl的缺掉足以在小鼠中复制NTDs，此中外显率和表达率都因母体叶酸缺少而加重。是以，常见的22q11.2缺掉会增添脑膜脊膜膨出的风险，弥补叶酸可以部门减轻这类风险。
▲ 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 ofCrkl,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.
Induction of social contagion for diverse outcomes in structured experiments in isolated villages
孤立村落布局尝试中分歧成果的社会沾染引诱
▲作者：EDOARDO M. AIROLDI AND NICHOLAS A. CHRISTAKIS
▲链接：
https://www.science.org/doi/10.1126/science.adi5147
▲摘要：
一些人在社会收集中占有拓扑位置，这加强了他们引诱溢出效应的有用性。我们在洪都拉斯176个孤立村落中24702人中构建了面临面收集，并按照分歧方式随机分派村落，改变了接管22个月健康教育方式的家庭比例和选择家庭的方式（随机分派法和“熟人保举”法）。
我们评估了117个分歧的常识、立场和实践成果。“熟人保举”法削减了到达全村特定程度所需的家庭数目。常识比行动更轻易传布，溢出效应扩大到分歧水平。更容易被采取的成果也表示出了更年夜的溢出效应。按照“熟人保举”成立的社交收集经由过程社会沾染有用增进了全平易近福利的改良。
▲ 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.
Locally narrow droplet size distributions are ubiquitous in stratocumulus clouds
部门狭小的液滴尺寸散布在层积云中遍及存在
▲作者：NITHIN ALLWAYIN, MICHAEL L. LARSEN et al.
▲链接：
https://www.science.org/doi/10.1126/science.adi5550
▲摘要：
当前，全球天气模式（GCMs）将云中的液滴尺寸散布参数化为普遍的云平均伽马。经由过程利用离散层积云体积的数字全息丈量，我们发现云中液滴尺寸散布在厘米标准上更窄，与云朵的平均值完全分歧。
这些局部门布偏向在构成更类似的云区域的“口袋”，每一个区域的特点是尺寸散布外形被稀释到分歧水平。这些不雅察成果为微物理进程的新建模表征斥地了道路。
▲ 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.