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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Machine learning for molecular simulations of crystal nucleation and growth
Not provided.
Increased selectivity in area-selective ALD by combining nucleation enhancement and SAM-based inhibition
Not provided.
Adsorption of Dy on Graphite (0001) Surface: Nucleation and Growth at 300 K
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Polysaccharide-catalyzed nucleation and growth of disordered dolomite: A potential precursor of sedimentary dolomite
This paper is about growing dolomite and even Mg-rich dolomite in presence of certain polysaccharides that could be major components in extracellular polymeric substances (EPS) of anaerobic bacteria like sulfate-reducing bacteria, methanogens and fermenters. This paper lays foundation for us to investigate roles of polysaccharide in governing compositions of Ca-Mg-carbonates and dolomite. Polysacchrides may be used as catalysts for enhancing stable Ca-Mg-carbonate (dolomite) in deep surface environment.
Study of the Nucleation and Growth of MOCVD YBCO on Oxide Buffered Metallic Tapes
Abstract not provided.
Microstructural Effects on Void Nucleation in Single-Phase Copper Polycrystals [Slides]
Abstract not provided.
Final Report. "Collaborative Project. Contributions of organic compounds to the growth of freshly nucleated atmospheric nanoparticles"
This is the final technical report for the portion of the project that took place at the National Center for Atmospheric Research, which covers approximately the first year of the three-year project. During this time we focused primarily on analysis and modeling of DOE-funded observations as well as preparation for laboratory studies of individual processes that contribute to atmospheric new particle formation.
Influence of Grain Boundary Properties and Orientation on Void Nucleation
No abstract provided.
Combining Novel Simulation Methods and Nucleation Theory to Uncover the Secrets of Gas Hydrates
Conventional computer simulation methods fail for some of the most important problems. With the design and application of innovative algorithms, this project achieved a breakthrough for the case of systems undergoing first-order phase transitions. We gave a complete simulation protocol based upon a well optimized version of our "generalized replica exchange method". The transition of primary interest was gas hydrate formation, a process of significance for climate science and natural gas retrieval. Since hydrates consist of guest molecules in the cages of a water matrix, β ice, the freezing and melting of water was also studied. New information was uncovered about the transition pathways and thermodynamics. Some highlights are 1. the finding that in a very dilute solution without deep supercooling, representative of real-world conditions and very challenging to conventional algorithms, methane can act as a catalyst to drive the formation of large amounts of β ice with empty cages as metastable intermediates, which might be filled by additional methane in a mechanism for hydrate formation, and 2. illumination of the role of metastable cubic ice in water freezing, with determination of the surface tensions of the cubic, hexagonal, and β ices, and the free energy difference of cubic vs hexagonal ice. Work was begun on lipid systems, bilayers and nanoreactors promising for energy-related photoreductions, and targets for future research. Our methods yielded what is arguably the most complete description of the composite lipid/water phases and the transition pathways among them.
Cluster Dynamics Modeling with Bubble Nucleation, Growth and Coalescence
The topic of this communication pertains to defect formation in irradiated solids such as plasma-facing tungsten submitted to helium implantation in fusion reactor com- ponents, and nuclear fuel (metal and oxides) submitted to volatile ssion product generation in nuclear reactors. The purpose of this progress report is to describe ef- forts towards addressing the prediction of long-time evolution of defects via continuum cluster dynamics simulation. The di culties are twofold. First, realistic, long-time dynamics in reactor conditions leads to a non-dilute di usion regime which is not accommodated by the prevailing dilute, stressless cluster dynamics theory. Second, long-time dynamics calls for a large set of species (ideally an in nite set) to capture all possible emerging defects, and this represents a computational bottleneck. Extensions beyond the dilute limit is a signi cant undertaking since no model has been advanced to extend cluster dynamics to non-dilute, deformable conditions. Here our proposed approach to model the non-dilute limit is to monitor the appearance of a spatially localized void volume fraction in the solid matrix with a bell shape pro le and insert an explicit geometrical bubble onto the support of the bell function. The newly cre- ated internal moving boundary provides the means to account for the interfacial ux of mobile species into the bubble, and the growth of bubbles allows for coalescence phenomena which captures highly non-dilute interactions. We present a preliminary interfacial kinematic model with associated interfacial di usion transport to follow the evolution of the bubble in any number of spatial dimensions and any number of bubbles, which can be further extended to include a deformation theory. Finally we comment on a computational front-tracking method to be used in conjunction with conventional cluster dynamics simulations in the non-dilute model proposed.
Collaborative Project: Contributions of organic compounds to the growth of freshly nucleated atmospheric nanoparticles. Final Report
New-particle formation (NPF) is a significant source of aerosol particles into the atmosphere. However, these particles are initially too small to have climatic importance and must grow, primarily through net uptake of low-volatility species and more volatile gases that react in particles to form stable compounds, from diameters of ~1 nm to 30–100 nm in order to potentially impact climate. At the present time there are uncertainties in the physical and chemical processes associated with the growth of these freshly formed particles that lead to uncertainties in model predictions of aerosol-climate interactions. In this project, we used a combination of field, laboratory, and modelling studies to understand the processes leading to nanoparticle growth and evaluated and improved growth in global aerosol models. During this period this research team has either participated in, or analyzed observations from, four DOE-funded campaigns: the 2013 New Particle Formation Study (NPFS) at the ARM Southern Great Plains (SGP) site; the 2013 Biogenic Aerosols – Effects on Clouds and Climate campaign (BAECC) in Hyytiala, Finland; Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) in central Amazonia, Brazil; and, most recently, the 2016 Holistic Interactions of Shallow Clouds, Aerosols, and Land-Ecosystems (HI-SCALE) campaign at the SGP site. In addition, the research team explored nanoparticle growth mechanisms in laboratory experiments at the National Center for Atmospheric Research, University of California, Irvine, and the CLOUD chamber in Geneva, Switzerland. Modeling efforts resulted in a process-level model that incorporated both salt formation and the uptake of low-volatility organic compounds, which was able to connect measurements of gas and nanoparticle phase compounds observed during NPFS. In total, the results of this work have been described in 32 peer-reviewed publications and 34 invited or conference presentations.
Final Report: Collaborative Project: Contributions of organic compounds to the growth of freshly nucleated atmospheric nanoparticles
New-particle formation (NPF) is a significant source of aerosol particles into the atmosphere. However, these particles are initially too small to have climatic importance and must grow, primarily through net uptake of low-volatility species and more volatile gases that react in particles to form stable compounds, from diameters of ~1 nm to 30–100 nm in order to potentially impact climate. At the present time there are uncertainties in the physical and chemical processes associated with the growth of these freshly formed particles that lead to uncertainties in model predictions of aerosol-climate interactions. In this project, we used a combination of field, laboratory, and modelling studies to understand the processes leading to nanoparticle growth and evaluated and improved growth in global aerosol models. During this period this research team has either participated in, or analyzed observations from, four DOE-funded campaigns: the 2013 New Particle Formation Study (NPFS) at the ARM Southern Great Plains (SGP) site; the 2013 Biogenic Aerosols – Effects on Clouds and Climate campaign (BAECC) in Hyytiala, Finland; Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) in central Amazonia, Brazil; and, most recently, the 2016 Holistic Interactions of Shallow Clouds, Aerosols, and Land-Ecosystems (HI-SCALE) campaign at the SGP site. In addition, the research team explored nanoparticle growth mechanisms in laboratory experiments at the National Center for Atmospheric Research, University of California, Irvine, and the CLOUD chamber in Geneva, Switzerland. Modeling efforts resulted in a process-level model that incorporated both salt formation and the uptake of low-volatility organic compounds, which was able to connect measurements of gas and nanoparticle phase compounds observed during NPFS. In total, the results of this work have been described in 32 peer-reviewed publications and 34 invited or conference presentations.
Nucleation and growth of metals on carbon surfaces
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Description of nucleation, growth and coagulation processes in the modeling of debris formation after a nuclear burst
Formulations of the principal physical processes active during the formation of nuclear debris are described, with an emphasis on first principles approaches and moderate computational costs. The discretization of these models for implementation into numerical codes is also discussed.
Nucleation, Growth, and Aggregation of Todorokite Nanoparticles from Both Geochemical and Materials Science Perspectives (Final Technical Report)
A vast amount of manganese (Mn) nodules exists in ocean sediments, covering about 30% of the ocean floor. Tunneled and layered Mn(IV) oxides, hereafter called TMOs and LMOs, are the primary mineral phases hosting Mn. Owing to their unique structure and properties, these Mn oxides are highly enriched in transition metals, platinum group metals, and rare earth elements, up to several percentages in weight. Thus, many metals are stored in these nodules and the nodules have thus been increasingly considered for their potential as a source of strategic metals for national security applications and the energy industry. The nodules also play an important role in trace metal biogeochemical cycling in the ocean because they control the partition and distribution of trace metals in oceanic sediments. Layered and tunneled structures differ in their mineralogical and chemical properties. For example, TMOs contain fewer metals compared to LMOs in ocean nodules. Therefore, the relative proportion of the two types of minerals in ocean nodules determines the metal sequestration capacities of the nodules, hence the amount of metals stored in the nodules and metal cycling in oceans. The overall objective of this study is to investigate the mechanisms of layered to tunneled structural transform driven by redox reactions. Specifically, we focus on the redox reactions between Mn(IV) and Mn(II) because they often coexist during Mn redox cycling.
Island decay on Pd (111): From adatom diffusion to nucleation.
Abstract not provided.