PNAS nexus最新文献

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Discovery tools: How powerful new scientific methods and instruments emerge and catalyze innovation. 发现工具:强大的新科学方法和仪器如何出现并促进创新。
IF 3.8
PNAS nexus Pub Date : 2026-04-09 eCollection Date: 2026-04-01 DOI: 10.1093/pnasnexus/pgag107
Alexander Krauss
{"title":"Discovery tools: How powerful new scientific methods and instruments emerge and catalyze innovation.","authors":"Alexander Krauss","doi":"10.1093/pnasnexus/pgag107","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgag107","url":null,"abstract":"<p><p>Powerful new methods and tools drive scientific progress-but how do we actually make such innovations? No theory yet explains how we invent major tools across fields. To address this gap, we examine all nobel-prize-winning method discoveries-that enabled breakthrough findings not possible without them-and we trace science's most influential toolmakers across fields, from Ernst Ruska's electron microscope and Kary Mullis's PCR method to Ernest Lawrence's particle accelerator. Here, we lay out the critical pathways taken to create these groundbreaking tools. We introduce a taxonomy of science's methods and tools: a scientific table of discovery methods that is a map of underexplored and unexplored method opportunities. By mapping the method landscape, we reveal gaps and possibilities that help guide where methods can be adapted, recombined, or strategically developed to catalyze discovery. It can help identify and predict untapped combinations of tools-and where the next breakthroughs can come from. What if we no longer wait for new discovery tools to emerge by chance but begin deliberately prioritizing their development? How many big breakthroughs are we missing because we have not yet strategically focused on designing the needed tools? We also outline the need for establishing methods labs and hubs-as incubators of innovation-that catalyze tool creation.</p>","PeriodicalId":74468,"journal":{"name":"PNAS nexus","volume":"5 4","pages":"pgag107"},"PeriodicalIF":3.8,"publicationDate":"2026-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13108597/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147791750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Building better antibody responses: The interplay of infection, vaccination, and immune imprinting. 建立更好的抗体反应:感染、疫苗接种和免疫印记的相互作用。
IF 3.8
PNAS nexus Pub Date : 2026-04-09 eCollection Date: 2026-04-01 DOI: 10.1093/pnasnexus/pgag110
L Carissa Aurelia, Kevin J Selva, Amy W Chung
{"title":"Building better antibody responses: The interplay of infection, vaccination, and immune imprinting.","authors":"L Carissa Aurelia, Kevin J Selva, Amy W Chung","doi":"10.1093/pnasnexus/pgag110","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgag110","url":null,"abstract":"<p><p>Antibodies are critical for protection against a range of viral respiratory diseases, including SARS-CoV-2, but the induction of durable and potent antibody responses continues to be a challenge. Beyond neutralization, there is growing appreciation for the potential protective role of Fc-mediated functions, especially against immune-evasive variants. Induction of polyfunctional antibody responses is a complex multifactorial process that is shaped by interactions between various antibody features, viral properties, and host factors. Here, we review lessons learned from the COVID-19 pandemic regarding how prior infection and different vaccination strategies can modulate plasma and mucosal antibody profiles, including isotypes, immunoglobulin G subclasses, Fc glycosylation, and consequently, antibody functions. Additionally, we discuss the challenges of immune imprinting and its effects upon antibody responses to viral variants. This review provides insights into optimizing antibody-based strategies for COVID-19 prevention and treatment, emphasizing the need for further research to understand the mechanisms behind effective antibody responses and their impact upon clinical outcomes.</p>","PeriodicalId":74468,"journal":{"name":"PNAS nexus","volume":"5 4","pages":"pgag110"},"PeriodicalIF":3.8,"publicationDate":"2026-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13098378/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147791709","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Astrocytic frataxin deficiency drives neurocognitive impairment in sickle cell mice. 星形细胞卵黄素缺乏导致镰状细胞小鼠神经认知障碍。
IF 3.8
PNAS nexus Pub Date : 2026-04-08 eCollection Date: 2026-04-01 DOI: 10.1093/pnasnexus/pgag106
Enrico M Novelli, Shane C Lenhart, Lesley M Foley, Nandinii Sekar, Paritosh Mondal, Hong Wang, T Kevin Hitchens, Samit Ghosh, Stephen Y Chan, Xiaoming Hu, Rimi Hazra
{"title":"Astrocytic frataxin deficiency drives neurocognitive impairment in sickle cell mice.","authors":"Enrico M Novelli, Shane C Lenhart, Lesley M Foley, Nandinii Sekar, Paritosh Mondal, Hong Wang, T Kevin Hitchens, Samit Ghosh, Stephen Y Chan, Xiaoming Hu, Rimi Hazra","doi":"10.1093/pnasnexus/pgag106","DOIUrl":"10.1093/pnasnexus/pgag106","url":null,"abstract":"<p><p>Individuals with sickle cell disease (SCD) suffer from a high burden of neurocognitive impairment. Cerebrovascular lesions, characterized by diffusion tensor imaging identified neuroaxonal damage, are associated with learning and memory deficits. The molecular and cellular intermediates driving microstructural neuroaxonal damage and cognitive impairment in SCD remain largely unexplored. Herein, we report that sickle cell mice (SS) have reduced expression of frataxin (FXN), a mitochondrial protein, in their astrocytes compared with normal control (AA) mice. A newly generated sickle bone marrow chimeric mouse with astrocyte-specific deletion of FXN (SS<sup>FXN-KO</sup>) showed worsening white-matter neuroaxonal damage compared with the normal mice lacking astrocytic FXN (AA<sup>FXN-KO</sup>) as well as with the SS mice with wild-type FXN expression (SS<sup>FXN-WT</sup>). The SS<sup>FXN-KO</sup> mice exhibited impaired cognitive function assessed by the functional novel object recognition (NOR) tests. Induction of FXN improved cognitive responses in the SS mice. Overall, our data demonstrate that astrocytic FXN plays a pivotal role in regulating neuroaxonal health and cognitive function in SCD.</p>","PeriodicalId":74468,"journal":{"name":"PNAS nexus","volume":"5 4","pages":"pgag106"},"PeriodicalIF":3.8,"publicationDate":"2026-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13108596/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147791653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Multistep coevolution of HIV-1 and human leukocyte antigen-C-restricted HIV-1-specific CD8+ T cells and the association with disease progression. HIV-1和人类白细胞抗原- c限制性HIV-1特异性CD8+ T细胞的多步共同进化及其与疾病进展的关系
IF 3.8
PNAS nexus Pub Date : 2026-04-07 eCollection Date: 2026-04-01 DOI: 10.1093/pnasnexus/pgag105
Takayuki Chikata, Tomohiro Akahoshi, Yu Zhang, Hung The Nguyen, Shinichi Oka, Hiroyuki Gatanaga, Masafumi Takiguchi
{"title":"Multistep coevolution of HIV-1 and human leukocyte antigen-C-restricted HIV-1-specific CD8<sup>+</sup> T cells and the association with disease progression.","authors":"Takayuki Chikata, Tomohiro Akahoshi, Yu Zhang, Hung The Nguyen, Shinichi Oka, Hiroyuki Gatanaga, Masafumi Takiguchi","doi":"10.1093/pnasnexus/pgag105","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgag105","url":null,"abstract":"<p><p>Disease progression during HIV-1 infection is proposed to correlate with the accumulation of virus variants that have evaded HIV-1-specific T cells; however, the multistep coevolution of HIV-1 with HIV-1-specific T cells has not been well investigated. Here, we analyzed the coevolution of HIV-1 with human leukocyte antigen (HLA)-C*14-restricted HIV-1-specific T cells in treatment-naive HLA-C*14<sup>+</sup> people living with HIV-1 (PLWH). The analyses of T cells specific for NefYT9 wild-type (WT) or escape mutant epitopes and HIV-1 sequences in HLA-C*14<sup>+</sup> PLWH suggested that NefQ125H was first selected by NefYT9 WT-specific T cells, then NefQ125D was selected by NefYT9-6H-specific T cells. This coevolution was confirmed by longitudinal analysis of HLA-C*14<sup>+</sup> PLWH. The CD4 count in NefQ125D virus-infected HLA-C*14<sup>+</sup> individuals was significantly lower than that in WT-virus-infected HLA-C*14<sup>+</sup> individuals, suggesting that accumulation of the NefQ125D mutant epitope correlates with disease progression. Our findings demonstrate that the multistep coevolution of HIV-1 with HLA-C-restricted HIV-1-specific T cells is associated with disease progression in HIV-1 infection.</p>","PeriodicalId":74468,"journal":{"name":"PNAS nexus","volume":"5 4","pages":"pgag105"},"PeriodicalIF":3.8,"publicationDate":"2026-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13096738/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147791701","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Tracing the origin of tropical North Atlantic Sargassum blooms to West Africa. 追踪热带北大西洋马尾藻的起源到西非。
IF 3.8
PNAS nexus Pub Date : 2026-04-07 eCollection Date: 2026-04-01 DOI: 10.1093/pnasnexus/pgag085
Francisco Javier Beron-Vera, María Josefina Olascoaga, Philippe Miron, Gage Bonner
{"title":"Tracing the origin of tropical North Atlantic <i>Sargassum</i> blooms to West Africa.","authors":"Francisco Javier Beron-Vera, María Josefina Olascoaga, Philippe Miron, Gage Bonner","doi":"10.1093/pnasnexus/pgag085","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgag085","url":null,"abstract":"<p><p>We simulate the dynamics of pelagic <i>Sargassum</i> rafts as systems of finite-size floating particles, governed by a Maxey-Riley law with nonlinear elastic interactions. Using surface ocean currents and wind data from reanalysis systems for clump transport, we computed trajectories within a domain covering the tropical and subtropical north Atlantic. The subsequent motion is reduced using Ulam's discretization method into a time-inhomogeneous Markov chain that simulates a background <i>Sargassum</i> concentration. Bayesian inversion, combined with nonautonomous transition path theory, was used to infer the origin of the first significant recorded bloom in the tropical North Atlantic, which unfolded in April 2011. Both methodologies independently identified the bloom's origin as near the West African coast, up to 2 years before it was detectable via satellite imagery on the basin's western side. This finding supports anecdotal evidence of <i>Sargassum</i> strandings on the Ghanaian coast in 2009. Moreover, it correlates with unusual environmental conditions-such as increased nutrient loads from significant upwelling linked to a pronounced Dakar Niña and Saharan dust deposition-that promote bloom proliferation. Additionally, it aligns with the observation that the species of <i>Sargassum</i> in the 2011 bloom differ from those in the Sargasso Sea, which might otherwise be considered a natural origin.</p>","PeriodicalId":74468,"journal":{"name":"PNAS nexus","volume":"5 4","pages":"pgag085"},"PeriodicalIF":3.8,"publicationDate":"2026-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13061127/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147647861","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Templateless crystallization of holococcolith crystals visualized by intracellular site-specific three-dimensional microscopy. 细胞内特异位点三维显微镜观察的全球藻晶体无模板结晶。
IF 3.8
PNAS nexus Pub Date : 2026-04-07 eCollection Date: 2026-04-01 DOI: 10.1093/pnasnexus/pgag104
Oz Ben-Joseph, Yu-Feng Meng, Lior Aram, Ikhlas Abu Freha, Zipora Lansky, Razi Safadi, Diede de Haan, Katya Rechav, Ifat Kaplan-Ashiri, Neta Varsano, Assaf Gal
{"title":"Templateless crystallization of holococcolith crystals visualized by intracellular site-specific three-dimensional microscopy.","authors":"Oz Ben-Joseph, Yu-Feng Meng, Lior Aram, Ikhlas Abu Freha, Zipora Lansky, Razi Safadi, Diede de Haan, Katya Rechav, Ifat Kaplan-Ashiri, Neta Varsano, Assaf Gal","doi":"10.1093/pnasnexus/pgag104","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgag104","url":null,"abstract":"<p><p>Biological crystallization generates some of the most intricate and diverse materials found in nature. Among the most striking examples are calcium carbonate structures called coccoliths, which are formed by unicellular marine algae. Despite the exquisite control over crystal orientations and arrangements, the mechanisms by which these cells control crystal nucleation remain poorly understood, largely due to the experimental difficulty of probing crystallization in vivo. Here, we report on intracellular crystallization during the formation of holococcoliths-superstructures assembled from rhombohedral calcite crystals. We establish a serial cryo-focused ion beam milling strategy to directly access the intracellular site where calcite precipitates. Cryo-electron tomography (cryoET) demonstrates a biomineralization mode where nucleation and growth of crystals occur within an isotropic environment and in the absence of any templating structures discernable by cryoET. Based on these observations, we propose a two-step mechanism, where an ordering step follows the initial random nucleation events. Such a process might be common to other biomineralization phenomena that evolve their order gradually.</p>","PeriodicalId":74468,"journal":{"name":"PNAS nexus","volume":"5 4","pages":"pgag104"},"PeriodicalIF":3.8,"publicationDate":"2026-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13089448/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147725011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Dietary inequality marker reveals 10,000 years of gender and cultural disparity in Europe. 饮食不平等标志揭示了欧洲一万年来的性别和文化差异。
IF 3.8
PNAS nexus Pub Date : 2026-04-07 eCollection Date: 2026-04-01 DOI: 10.1093/pnasnexus/pgag033
Rozenn Colleter, Klervia Jaouen, Dominique Garcia, Michael P Richards
{"title":"Dietary inequality marker reveals 10,000 years of gender and cultural disparity in Europe.","authors":"Rozenn Colleter, Klervia Jaouen, Dominique Garcia, Michael P Richards","doi":"10.1093/pnasnexus/pgag033","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgag033","url":null,"abstract":"<p><p>Diet is a key to evaluating social and health inequalities over time, as it reflects disparities in access to resources often linked to socioeconomic and gender factors. Stable carbon and nitrogen isotopes, while semi-quantitative, typically limit intersite comparisons, as the results are tied to local baseline isotope values. In this study, we overcome this limitation by applying the interdecile ratio-a metric from economics-to isotope data from 12,281 individuals across 393 European sites over millennia. Our isotope-based dietary inequality index reveals the nonlinear evolution of dietary disparities over time and across different geographical areas. Sex-based disparities are evident throughout all time periods. Male individuals are consistently overrepresented in the upper deciles, indicating greater access to animal proteins, while females dominate the lower deciles, reflecting more restricted access. Neolithic societies exhibit homogeneous diets at the population level, but animal protein consumption tends to differ between men and women. As expected, Bronze Age carbon interdecile indexes mark increasing dietary inequality, likely linked to agricultural advances and social hierarchies. Dietary disparities peak during Antiquity, although the gap between the sexes narrows slightly. This diachronic analysis highlights the complex interactions between diet, social structures, and gender and provides a robust framework for comparative studies of health inequalities in archaeology.</p>","PeriodicalId":74468,"journal":{"name":"PNAS nexus","volume":"5 4","pages":"pgag033"},"PeriodicalIF":3.8,"publicationDate":"2026-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13064645/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147679254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Decomposing the neurocomputational mechanisms of deontological moral preferences. 分解义务论道德偏好的神经计算机制。
IF 3.8
PNAS nexus Pub Date : 2026-04-07 eCollection Date: 2026-04-01 DOI: 10.1093/pnasnexus/pgag074
Yoonseo Zoh, Soyeon Kim, Hackjin Kim, M J Crockett, Woo-Young Ahn
{"title":"Decomposing the neurocomputational mechanisms of deontological moral preferences.","authors":"Yoonseo Zoh, Soyeon Kim, Hackjin Kim, M J Crockett, Woo-Young Ahn","doi":"10.1093/pnasnexus/pgag074","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgag074","url":null,"abstract":"<p><p>Research on the neurocomputational mechanisms of moral judgment has typically focused on contrasting \"utilitarian\" preferences to impartially maximize aggregate welfare and \"deontological\" preferences that judge the morality of actions based on rules. However, there has been little work to decompose the cognitive subcomponents of deontological preferences. Here, we investigated the neurocomputational mechanisms underlying two types of deontological preferences (Rawlsian and Kantian) and their contrast with utilitarian preferences in an incentivized moral dilemma task. Participants repeatedly decided how to allocate harm between a single individual (\"the one\") and a group of three to four individuals (\"the group\"). The task distinguished preferences for Rawlsian, Kantian, and utilitarian strategies by quantifying trade-offs among active harm, concern for the worst-off individual, and overall utility. Behaviorally, participants favored the Rawlsian strategy, preferring to impose more harm overall rather than disproportionately harm the one individual. Computational modeling revealed two dissociable dimensions of individual variability in Rawlsian preferences: (i) minimizing the maximum amount of harm delivered to a single person and (ii) subjective threshold of acceptable amount of harm imposed on one person. The combination of univariate and multivariate functional MRI analyses revealed the engagement of distinct brain regions in these two dimensions of Rawlsian preferences, which respectively mapped onto activity in mentalizing and valuation networks. Our results reveal the neurocomputational mechanisms guiding trade-offs between the welfare of one versus a larger group and highlight distinct roles for the mentalizing and valuation networks in shaping Rawlsian moral preferences.</p>","PeriodicalId":74468,"journal":{"name":"PNAS nexus","volume":"5 4","pages":"pgag074"},"PeriodicalIF":3.8,"publicationDate":"2026-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13064635/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147679140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
AI is not replacing engineers: It is empowering them. 人工智能不是在取代工程师,而是在赋予他们权力。
IF 3.8
PNAS nexus Pub Date : 2026-04-07 eCollection Date: 2026-04-01 DOI: 10.1093/pnasnexus/pgag043
Tsu-Jae Liu
{"title":"AI is not replacing engineers: It is empowering them.","authors":"Tsu-Jae Liu","doi":"10.1093/pnasnexus/pgag043","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgag043","url":null,"abstract":"","PeriodicalId":74468,"journal":{"name":"PNAS nexus","volume":"5 4","pages":"pgag043"},"PeriodicalIF":3.8,"publicationDate":"2026-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13064633/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147679387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Crystallization of stardust analogs under an electron flux atmosphere. 电子通量大气下星尘类似物的结晶。
IF 3.8
PNAS nexus Pub Date : 2026-04-04 eCollection Date: 2026-04-01 DOI: 10.1093/pnasnexus/pgag095
Rakibul A Shohan, Cody Cly, Angela Speck, Benjamin Sargent, Joseph A Nuth, Alan Whittington, Arturo Ponce
{"title":"Crystallization of stardust analogs under an electron flux atmosphere.","authors":"Rakibul A Shohan, Cody Cly, Angela Speck, Benjamin Sargent, Joseph A Nuth, Alan Whittington, Arturo Ponce","doi":"10.1093/pnasnexus/pgag095","DOIUrl":"https://doi.org/10.1093/pnasnexus/pgag095","url":null,"abstract":"<p><p>The atomic microstructural evolution of circumstellar dust grains, which seed the interstellar medium, remains poorly understood. Amorphous alumina and its crystalline polymorphs, including corundum, have been found in the circumstellar shell of evolved stars. Evidence includes both astronomical observations of mid-infrared spectroscopic features and laboratory analyses of presolar grains. In this work, we show that electron fluxes can stimulate crystallization of amorphous alumina stardust analog materials using transmission electron microscopy. Crystallization experiments conducted at varying electron energies and flux conditions demonstrate a critical threshold cumulative electron dose of ∼10<sup>24</sup> e<sup>-</sup>/m<sup>2</sup> for crystallization, suggesting that the crystallization process can occur through atomic rearrangement due to electron interaction with the amorphous matrix. Throughout the crystallization process, time-resolved diffraction reveals the transition from amorphous to a transitional η-Al<sub>2</sub>O<sub>3</sub> phase. The same transitional phase was confirmed to occur via thermal annealing at 800 °C, while annealing at 1,300 °C produced the stable crystalline phase α-Al<sub>2</sub>O<sub>3</sub> (corundum). In both processes, the structural evolution through atomic rearrangement was characterized by quantifying the average interatomic distance between neighboring atoms using the electron pair distribution function analysis. Extrapolating to astronomical timescales, our findings suggest that electron bombardment may play a significant role in the crystallization of stardust grains, highlighting its potential importance in astrophysical environments, such as the circumstellar envelopes of planetary nebulae.</p>","PeriodicalId":74468,"journal":{"name":"PNAS nexus","volume":"5 4","pages":"pgag095"},"PeriodicalIF":3.8,"publicationDate":"2026-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13070425/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147679509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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