编译|未玖

Science, 4 APR 2025, VOL 388, ISSUE 6742

《科学》2025年4月4日，第388卷，6742期

材料科学Materials Science

Superior resistance to cyclic creep in a gradient structured steel

梯度结构钢具有优异的抗循环蠕变性能

▲ 作者：QINGSONG PAN, KUNQING DING, SONG GUO, NING LU, NAIRONG TAO, TING ZHU, ET AL.

▲链接：

https://www.science.org/doi/10.1126/science.adt6666

▲摘要：

循环蠕变，或棘轮效应，是一种严重的疲劳变形形式，在非对称应力循环和非零平均应力下由塑性应变单向累积引起。它经常导致结构材料过早失效，提高抗棘轮效应是材料工程中的一大挑战。

研究组证明了具有梯度序构位错胞的高强度奥氏体不锈钢的优越抗棘轮效应。棘轮应变速率比粗粒度对应物低2~4个数量级。其阻力源于在稳定位错胞内通过变形诱导的相干马氏体转变为密排六方纳米层的持续微观结构细化。

逐渐细化的微观结构减轻了循环软化，抑制了应力循环过程中的局部应变，从而降低了棘轮应变。梯度位错结构代表了高强度、抗棘轮效应材料的一种颇有前景的设计。

▲ Abstract：

Cyclic creep, or ratcheting, is a severe form of fatigue deformation caused by cumulative unidirectional plastic strain under asymmetrical stress cycling with a nonzero mean stress. It often causes premature failure of structural materials, and enhancing ratcheting resistance is a challenge in materials engineering. We demonstrate superior ratcheting resistance in high-strength austenitic stainless steel with a gradient hierarchy of dislocation cells. The ratcheting rate is two to four orders of magnitude lower than for coarse-grained counterparts. Its resistance results from sustained microstructural refinement through deformation-induced coherent martensitic transformations to hexagonal close-packed nanolayers within stable dislocation cells. The progressively refined microstructure mitigates cyclic softening and suppresses strain localization during stress cycling, thus reducing ratcheting strain. The gradient dislocation architecture represents a promising design for high-strength, ratcheting-resistant materials.

Strain-induced rubidium incorporation into wide-bandgap perovskites reduces photovoltage loss

应变诱导铷掺入宽带隙钙钛矿降低光电压损失

▲ 作者：LIKAI ZHENG, MINGYANG WEI, FELIX T. EICKEMEYER, JING GAO, BIN HUANG, UMMUGULSUM GUNES, ET AL.

▲链接：

https://www.science.org/doi/10.1126/science.adt3417

▲摘要：

A位阳离子混合可以增强宽带隙（WBG）钙钛矿的光伏性能，但铷（Rb）阳离子混合通常形成非钙钛矿相。

研究组报道，晶格应变将Rb离子锁定在三卤化物WBG钙钛矿晶格的α—相中，防止相偏析成非钙钛矿富铷—铯相。这一过程与氯离子调节配合，促进了卤化物在整个薄膜体积上的均匀分布。得到的1.67电子伏特WBG钙钛矿在1太阳当量照射下的光致发光量子产率超过14%，对应于约1.34电子伏特的准费米能级分裂。

研究组制备的WBG钙钛矿太阳能电池开路电压（VOC）为1.30伏，相当于辐射VOC极限的93.5%，相对于WBG钙钛矿中观察到的理论限值，其光电压损失最低。

▲ Abstract：

A-site cation mixing can enhance the photovoltaic performance of a wide-bandgap (WBG) perovskite, but rubidium (Rb) cation mixing generally forms a nonperovskite phase. We report that lattice strain locks Rb ions into the α-phase of the lattice of a triple-halide WBG perovskite, preventing phase segregation into a nonperovskite Rb-cesium–rich phase. This process cooperates with chloride accommodation and promotes halide homogenization across the entire film volume. The resulting 1.67–electron volt WBG perovskite exhibits photoluminescence quantum yields exceeding 14% under 1-sun-equivalent irradiation, corresponding to a quasi–Fermi level splitting of ~1.34 electron volts. A WBG perovskite solar cell with an open-circuit voltage (VOC) of 1.30 volts was prepared, corresponding to 93.5% of the radiative VOC limit and representing the lowest photovoltage loss relative to the theoretical limit observed in WBG perovskites.

影像学Imaging

Nonlinear sound-sheet microscopy: Imaging opaque organs at the capillary and cellular scale

非线性声片显微镜：在毛细血管和细胞尺度上成像不透明器官

▲ 作者：BAPTISTE HEILES, FLORA NELISSEN, RICK WAASDORP, DION TERWIEL, BYUNG MIN PARK, ELEONORA MUNOZ IBARRA, ET AL.

▲链接：

https://www.science.org/doi/10.1126/science.ads1325

▲摘要：

光片荧光显微镜通过三维可视化动态细胞过程极大地推动了生物学研究。然而，厚组织中的光散射和荧光标记物的光漂白限制了这种方法在研究薄或半透明标本中的应用。

研究组将非衍射超声光束与交叉振幅调制序列和非线性声学对比剂相结合，以实现目标生物功能的快速和体积成像。他们报道了在立方厘米尺度上使用基因编码的气囊泡对肿瘤基因表达进行体积成像，以及使用血管内微泡造影剂实现脑毛细血管网络的定位成像。

与生物分子超声的最新技术相比，非线性声片显微镜的成像速度提高了64倍，成像体积增加了35倍，经典成像分辨率提高了4倍。

▲ Abstract：

Light-sheet fluorescence microscopy has revolutionized biology by visualizing dynamic cellular processes in three dimensions. However, light scattering in thick tissue and photobleaching of fluorescent reporters limit this method to studying thin or translucent specimens. In this study, we applied nondiffractive ultrasound beams in conjunction with a cross-amplitude modulation sequence and nonlinear acoustic reporters to enable fast and volumetric imaging of targeted biological functions. We reported volumetric imaging of tumor gene expression at the cubic centimeter scale using genetically encoded gas vesicles and localization microscopy of cerebral capillary networks using intravascular microbubble contrast agents. Nonlinear sound-sheet microscopy provides a ~64× acceleration in imaging speed, ~35× increase in imaged volume, and ~4× increase in classical imaging resolution compared with the state of the art in biomolecular ultrasound.

化学Chemistry

Homogeneous-heterogeneous bifunctionality in Pd-catalyzed vinyl acetate synthesis

钯催化乙酸乙烯酯合成中的均相-非均相双官能性

▲ 作者：DEIAA M. HARRAZ, KUNAL M. LODAYA, BRYAN Y. TANG AND YOGESH SURENDRANATH

▲链接：

https://www.science.org/doi/10.1126/science.ads7913

▲摘要：

目前，催化的机理范式通常认为，活性物种在整个反应过程中要么保持均相，要么保持非均相。

研究组展示了一个重要的工业过程，即钯（Pd）催化乙酸乙烯酯合成，通过在催化过程中非均相Pd(0)和均相Pd(II)的相互转化进行，两种物种起到互补的作用。利用电化学探针技术，他们发现非均相Pd(0)纳米颗粒作为活性氧还原电催化剂，提供腐蚀形成均相Pd(II)所需的高电位，然后通过非均相Pd(0)的重整催化选择性乙烯乙酰氧基化。

电流保护抑制Pd(0)对Pd(II)的腐蚀导致催化作用的可逆性中毒，证明了相转化在催化循环中的重要作用。这些结果凸显了动态相的相互转化如何利用及耦合分子和材料活性位点的互补反应性。

▲ Abstract：

Presently, mechanistic paradigms in catalysis generally posit that the active species remains either homogeneous or heterogeneous throughout the reaction. In this work, we show that a prominent industrial process, palladium (Pd)–catalyzed vinyl acetate synthesis, proceeds via interconversion of heterogeneous Pd(0) and homogeneous Pd(II) during catalysis, with each species playing a complementary role. Using electrochemical probes, we found that heterogeneous, nanoparticulate Pd(0) serves as an active oxygen reduction electrocatalyst to furnish the high potential required for corrosion to form homogeneous Pd(II), which then catalyzes selective ethylene acetoxylation with reformation of heterogeneous Pd(0). Inhibiting the corrosion of Pd(0) to Pd(II) by galvanic protection results in reversible poisoning of catalysis, evincing the essential role of phase conversion in this catalytic cycle. These results highlight how dynamic phase interconversion can harness and couple complementary reactivity across molecular and material active sites.

地球科学Earth Science

A geological timescale for bacterial evolution and oxygen adaptation

细菌进化和氧适应的地质时间尺度

▲ 作者：ADRIáN A. DAVíN, BEN J. WOODCROFT, ROCHELLE M. SOO, BENOIT MOREL, RANJANI MURALI, DOMINIK SCHREMPF, ET AL.

▲链接：

https://www.science.org/doi/10.1126/science.adp1853

▲摘要：

微生物生命在地球历史上占据主导地位，但留下的化石记录很少，这极大地阻碍了人们对深时间进化的理解。然而，细菌代谢在地球化学记录中留下了信号，最显著的是大氧化事件（GOE）。

研究组结合机器学习和系统发育协调来推断祖先细菌向有氧生活方式的转变，并将其与GOE联系起来，以校准细菌发育时间树。现存细菌门的多样性可追溯到太古宙和元古代，部分细菌科可追溯至显生宙之前。

研究组推断，大多数细菌门的祖先是厌氧菌，在GOE之后采用了需氧的生活方式。然而，在蓝藻祖先中，有氧代谢可能早于GOE，这可能促进了含氧光合作用的演化。

▲ Abstract：

Microbial life has dominated Earth’s history but left a sparse fossil record, greatly hindering our understanding of evolution in deep time. However, bacterial metabolism has left signatures in the geochemical record, most conspicuously the Great Oxidation Event (GOE). We combine machine learning and phylogenetic reconciliation to infer ancestral bacterial transitions to aerobic lifestyles, linking them to the GOE to calibrate the bacterial time tree. Extant bacterial phyla trace their diversity to the Archaean and Proterozoic, and bacterial families prior to the Phanerozoic. We infer that most bacterial phyla were ancestrally anaerobic and adopted aerobic lifestyles after the GOE. However, in the cyanobacterial ancestor, aerobic metabolism likely predated the GOE, which may have facilitated the evolution of oxygenic photosynthesis.

公共卫生Public Health

Vaccine-enhanced competition permits rational bacterial strain replacement in the gut

疫苗增强竞争实现肠道内合理的细菌菌株替换

▲ 作者：VERENA LENTSCH, AURORE WOLLER, ANDREA ROCKER, SELMA ASLANI, CLAUDIA MORESI, NIINA RUOHO, ET AL.

▲链接：

https://www.science.org/doi/10.1126/science.adp5011

▲摘要：

肠道定植先于一系列肠致病菌和机会致病菌的侵袭性感染。

研究组表明，将口服疫苗与工程或特定筛选的生态位竞争菌株相结合，可清除小鼠肠道内的病原体并实现菌株替换。这种方法不仅能预防非伤寒沙门氏菌菌株的入侵，还可以治疗性替换已定植的大肠杆菌。

完整的适应性免疫和代谢生态位竞争对于有效的疫苗增强菌株竞争都是必要的。该研究结果表明，粘膜抗体已经进化到通过影响竞争结果在肠道微生物生态环境中起作用。这对消除致病性和抗生素耐药细菌库，以及合理的微生物群工程具有重要意义。

▲ Abstract：

Colonization of the intestinal lumen precedes invasive infection for a wide range of enteropathogenic and opportunistic pathogenic bacteria. We show that combining oral vaccination with engineered or selected niche-competitor strains permits pathogen exclusion and strain replacement in the mouse gut lumen. This approach can be applied either prophylactically to prevent invasion of nontyphoidal Salmonella strains, or therapeutically to displace an established Escherichia coli. Both intact adaptive immunity and metabolic niche competition are necessary for efficient vaccine-enhanced competition. Our findings imply that mucosal antibodies have evolved to work in the context of gut microbial ecology by influencing the outcome of competition. This has broad implications for the elimination of pathogenic and antibiotic-resistant bacterial reservoirs and for rational microbiota engineering.