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Genesis of Nanogalvanic Corrosion Revealed in Pearlitic Steel
Nanoscale, localized corrosion underpins billions of dollars in damage and material costs each year; however, the processes responsible have remained elusive due to the complexity of studying degradative material behavior at nanoscale liquid–solid interfaces. Recent improvements to liquid cell scanning/transmission electron microscopy and associated techniques enable this first look at the nanogalvanic corrosion processes underlying this widespread damage. Nanogalvanic corrosion is observed to initiate at the near-surface ferrite/cementite phase interfaces that typify carbon steel. In minutes, the corrosion front delves deeper into the material, claiming a thin layer of ferrite around all exposed phase boundaries before progressing laterally, converting the ferrite to corrosion product normal to each buried cementite grain. Over the following few minutes, the corrosion product that lines each cementite grain undergoes a volumetric expansion, creating a lateral wedging force that mechanically ejects the cementite grains from their grooves and leaves behind percolation channels into the steel substructure.
Genesis of the periodic lattice distortions in the charge density wave state of 2 H- TaSe 2
Using high-energy x-ray diffraction and large-scale three-dimensonal structure modeling, we reveal the evolution of local lattice distortions in the archetypal charge density wave (CDW) system 2 H- TaSe 2 as it is cooled from its normal state above room temperature down to temperature where Ta atoms form a long-range ordered superstructure. In particular, we find that the structure is formed via a gradual in-plane clustering of Ta atoms exhibiting unusually short bonding distances already near room temperature, and not via a cooperative distortion of Ta atomic planes taking place at the critical ordering temperature. Our findings clarify the debated local symmetry and magnitude of the periodic lattice distortions in the CDW state of 2 H- TaSe 2 , and emphasize the role of locally correlated lattice distortions as a precursor of CDWs in low-dimensional solids. Further, we demonstrate an efficient experimental approach to study them.
Genesis and atomic structure of the charge density wave phase of 1T-VSe 2
Using variable temperature total x-ray scattering, we study the emergence of charge density wave (CDW) order in the archetypal transition-metal dichalcogenide (TMDC) 1𝑇−VSe 2 . Here, we find that a CDW precursor phase (PF) appears at 𝑇 CDW(PF) of 200(5) K, where V and Se atoms experience in- and out-of-plane static displacements from their position in the undistorted lattice, respectively. The displacements increase with decreasing temperature and a little-known superstructure of V triatomic clusters emerges below 𝑇 CDW(3D) of 100(5) K, where three-dimensional CDW order sets in. Concurrently, Se atoms form less well-defined dimers. Thus, similarly to other TMDCs, 1𝑇−VSe 2 appears to exhibit a two-step CDW transition. The finding underlines the key contribution of lattice distortions to the emergence of CDW order in 1𝑇−VSe 2 and generally in TMDCs.
Gravitational waves from neutrino mass and dark matter genesis
Not Available
LANL "What Do We Get" Report: 238 U GENESIS Meeting [Slides]
Abstract not provided.
Shale gas: Geochemical and physical constraints on genesis, storage, and producibility
Our research project on shale gas included two tasks: (1) Testing of different shales’ ability to geocatalytically generate natural gas at low temperatures; verification of geocatalytic methanogenesis would potentially render shale gas a quasi-renewable resource, and (2) quantification and characterization of porosity and permeability in organic-rich rocks with implication for producibility. Adequate porosity is required for geological storage of shale gas. At the same time, pore connectivity is essential for gas producibility.
Coffee Chat: A Unifying Exemplar of Systems Engineering leveraging Vitech GENESYS and MathWorks Simulink interoperability
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Structured Requirements Generation from GENESYS
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Structured Requirements Generation from GENESYS
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The Genesis of Technoscientific Revolutions: Rethinking the Nature and Nurturing of Research.
Abstract not provided.
The Genesis of Technoscientific Revolutions: Rethinking the Nature and Nurture of Research.
Abstract not provided.
Generative Embeddings Network-based Semantic Inference and Search (GENESIS)
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Spontaneous Cyclogenesis without Radiative and Surface-Flux Feedbacks
Tropical cyclones (TCs) are among the most intense and feared storms in the world. What physical processes lead to cyclogenesis remains the most mysterious aspect of TC physics. Here, we study spontaneous TC genesis in rotating radiative–convective equilibrium using cloud-resolving simulations over an f plane with constant sea surface temperature. Previous studies proposed that spontaneous TC genesis requires either radiative or surface-flux feedbacks. To test this hypothesis, we perform mechanism-denial experiments, in which we switch off both feedback processes in numerical simulations. We find that TCs can self-emerge even without radiative and surface-flux feedbacks. Although these feedbacks accelerate the genesis and impact the size of the TCs, TCs in the experiments without them can reach similar intensities as those in the control experiment. We show that TC genesis is associated with an increase in the available potential energy (APE) and that convective heating dominates the APE production. Overall, our result suggests that spontaneous TC genesis may result from a cooperative interaction between convection and circulation and that radiative and surface-flux feedbacks accelerate the process. Furthermore, we find that increasing the planetary rotation favors spontaneous TC genesis.