Water-in-Salt LiTFSI Aqueous Electrolytes. 1. Liquid Structure from Combined Molecular Dynamics Simulation and Experimental Studies
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Zhang, Yong↗
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Cyclic Peptides for Lanthanide Binding
Lanthanide ions are difficult to separate from one another due to their similar chemical properties. The discovery of lanthanide-binding peptides and proteins in nature has led to an increased interest in the possibility of utilizing the strong binding of peptides to lanthanide ions for their separations; as such, there has been an effort to identify or design peptides with improved lanthanide binding and selectivity toward particular lanthanide ions. Here, in this study, we designed and characterized lanthanide-binding cyclic peptides (LBCPs) with molecular dynamics simulations, electronic structure calculations, and emission spectroscopy. Luminescent decay measurements were done to determine the number of water molecules coordinated to the Eu 3+ ion in Eu-LBCP complexes and compare to the predicted number of water molecules by computation to assess the lanthanide-binding affinity of LBCPs. Measured stability constants show binding of the LBCPs to the Eu 3+ ion with stronger than micromolar affinity. We were able to identify multiple peptides that selectively bind to middle lanthanides. We describe the structural basis of the lanthanide-binding selectivity trend with strongest binding to the middle lanthanides, followed by the heavier lanthanides, and finally to the lighter ions.
ions↗
The Contributions of Shear and Turbulence to Cloud Overlap for Cumulus Clouds
The causes of vertical cloud overlap, the ratio between the cloud fraction by area and the cloud fraction by volume, are studied for fields of cumulus convection. Using large-eddy simulations, the structure of individual clouds within the cloud field is inspected and connected to the overall cloud cover of the entire cloud field. First, it is shown that the cloud overlap of the entire field can be well approximated by the total cloud overlap of the individual clouds. It is then shown that a simple maximum overlap assumption, which is commonly used for cloud fields with small layer depth, can only account for roughly half of the overlap inefficiency. This is due to the fact that maximum overlap only represents variations in cloud width as a function of depth but does not take other factors into account, most notably shear or turbulence. The effects of turbulence and wind shear on the overlap of individual clouds are first estimated as a function of cloud depth, which closes the discrepancy between observed cloud overlap and the maximum overlap assumption. Then, an empirical model is developed for the shear and turbulence contributions on overlap as a function of cloud depth and of synoptic conditions. Finally, it is shown that our model is capable of accurately predicting overlap for a large number of cloud fields and under a variety of meteorological conditions.
54 ENVIRONMENTAL SCIENCES↗
Multidimensional quantitative phenotypic and molecular analysis reveals neomorphic behaviors of p53 missense mutants
Abstract Mutations in the TP53 tumor suppressor gene occur in >80% of the triple-negative or basal-like breast cancer. To test whether neomorphic functions of specific TP53 missense mutations contribute to phenotypic heterogeneity, we characterized phenotypes of non-transformed MCF10A-derived cell lines expressing the ten most common missense mutant p53 proteins and observed a wide spectrum of phenotypic changes in cell survival, resistance to apoptosis and anoikis, cell migration, invasion and 3D mammosphere architecture. The p53 mutants R248W, R273C, R248Q, and Y220C are the most aggressive while G245S and Y234C are the least, which correlates with survival rates of basal-like breast cancer patients. Interestingly, a crucial amino acid difference at one position—R273C vs. R273H—has drastic changes on cellular phenotype. RNA-Seq and ChIP-Seq analyses show distinct DNA binding properties of different p53 mutants, yielding heterogeneous transcriptomics profiles, and MD simulation provided structural basis of differential DNA binding of different p53 mutants. Integrative statistical and machine-learning-based pathway analysis on gene expression profiles with phenotype vectors across the mutant cell lines identifies quantitative association of multiple pathways including the Hippo/YAP/TAZ pathway with phenotypic aggressiveness. Further, comparative analyses of large transcriptomics datasets on breast cancer cell lines and tumors suggest that dysregulation of the Hippo/YAP/TAZ pathway plays a key role in driving the cellular phenotypes towards basal-like in the presence of more aggressive p53 mutants. Overall, our study describes distinct gain-of-function impacts on protein functions, transcriptional profiles, and cellular behaviors of different p53 missense mutants, which contribute to clinical phenotypic heterogeneity of triple-negative breast tumors.
60 APPLIED LIFE SCIENCES↗
Code interoperability extends the scope of quantum simulations
The functionality of many materials is critically dependent on the integration of dissimilar components and on the interfaces that arise between them. The description of such heterogeneous components requires the development and deployment of first principles methods, coupled to appropriate dynamical descriptions of matter and advanced sampling techniques, in order to capture all the relevant length and time scales of importance to the materials’ performance. It is thus essential to build simple, streamlined computational schemes for the prediction and design of multiple properties of broad classes of materials, by developing interoperable codes which can be efficiently coupled to each other to perform complex tasks. We discuss the use of interoperable codes to simulate the structural and spectroscopic characterization of materials, including chemical reactions for catalysis, the description of defects for quantum information science, and heat and charge transport.
36 MATERIALS SCIENCE↗
Si photocathode with Ag-supported dendritic Cu catalyst for CO 2 reduction
Si photocathodes integrated with Ag-supported dendritic Cu catalysts are used to perform light-driven reduction of CO 2 to C 2 and C 3 products in aqueous solution. A back illumination geometry with an n-type Si absorber was used to permit the use of absorbing metallic catalysts. Selective carrier collection was accomplished by a p + implantation on the illumination side and an n + implantation followed by atomic layer deposition of TiO 2 on the electrolyte site. The Ag-supported dendritic Cu CO 2 reduction catalyst was formed by evaporation of Ag followed by high-rate electrodeposition of Cu to form a high surface area structure. Under simulated 1 sun illumination in 0.1 M CsHCO 3 saturated with CO 2 , the photovoltage generated by the Si (~600 mV) enables C 2 and C 3 products to be produced at -0.4 vs. RHE. Texturing of both sides of the Si increases the light-limited current density, due to reduced reflection on the illumination side, and also deceases the onset potential. Under simulated diurnal illumination conditions photocathodes maintain over 60% faradaic efficiency to hydrocarbon and oxygenate products (mainly ethylene, ethanol, propanol) for several days. After 10 days of testing, contamination from the counter electrode is observed, which causes an increase in hydrogen production. This effect is mitigated by a regeneration procedure which restores the original catalyst selectivity. Finally, a tandem, self-powered CO 2 reduction device was formed by coupling a Si photocathode with two series-connected semitransparent CH 3 NH 3 PbI 3 perovskite solar cells, achieving an efficiency for the conversion of sunlight to hydrocarbons and oxygenates of 1.5% (3.5% for all products).
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Coordination changes in liquid tin under shock compression determined using in situ femtosecond x-ray diffraction
Little is known regarding the liquid structure of materials compressed to extreme conditions, and even less is known about liquid structures undergoing rapid compression on nanosecond timescales. Here, we report on liquid structure factor and radial distribution function measurements of tin shock compressed to 84(19) GPa. High-quality, femtosecond x-ray diffraction measurements at the Linac Coherent Light Source were used to extract the liquid diffuse scattering signal. From the radial distribution function, we find that the structural evolution of the liquid with increasing pressure mimics the evolution of the solid phase. With increasing pressure, we find that the liquid structure evolves from a complex structure, with a low coordination number, to a simple liquid structure with a coordination number of ~12. We provide a pathway for future experiments to study liquids at elevated pressures using high-energy lasers to shock compress materials beyond the reach of static diamond anvil cell techniques.
X-ray diffraction↗
Dynamic and weak electric double layers in ultrathin nanopores
The unique properties of aqueous electrolytes in ultrathin nanopores have drawn a great deal of attention in a variety of applications, such as power generation, water desalination, and disease diagnosis. Inside the nanopore, at the interface, properties of ions differ from those predicted by the classical ionic layering models (e.g., Gouy–Chapman electric double layer) when the thickness of the nanopore approaches the size of a single atom (e.g., nanopores in a single-layer graphene membrane). Here, using extensive molecular dynamics simulations, the structure and dynamics of aqueous ions inside nanopores are studied for different thicknesses, diameters, and surface charge densities of carbon-based nanopores [ultrathin graphene and finite-thickness carbon nanotubes (CNTs)]. The ion concentration and diffusion coefficient in ultrathin nanopores show no indication of the formation of a Stern layer (an immobile counter-ionic layer) as the counter-ions and nanopore atoms are weakly correlated in time compared to the strong correlation observed in thick nanopores. The weak correlation observed in ultrathin nanopores is indicative of a weak adsorption of counter-ions onto the surface compared to that of thick pores. The vanishing counter-ion adsorption (ion–wall correlation) in ultrathin nanopores leads to several orders of magnitude shorter ionic residence times (picoseconds) compared to the residence times in thick CNTs (seconds). The results of this study will help better understand the structure and dynamics of aqueous ions in ultrathin nanopores.
2D materials↗
Nature of the bonded-to-atomic transition in liquid silica to TPa pressures
First-principles calculations and analysis of the thermodynamic, structural, and electronic properties of liquid SiO 2 characterize the bonded-to-atomic transition at 0.1–1.6 TPa and 10 4 –10 5 K (1–9 eV), the high-energy-density regime relevant to understanding planetary interiors. We find strong ionic bonds that become short-lived due to high kinetics during the transition, with sensitivity of the transition temperature to pressure, and our calculated Hugoniots agree with past experimental data. Furthermore, these results reconcile previous experimental and theoretical findings by clarifying the nature of the bond dissociation process in early Earth and “rocky” (oxide) constituents of large planets.
74 ATOMIC AND MOLECULAR PHYSICS↗
Two-Step Procedure for Liquid-Salt-Cooled-Reactor Analysis
Here, this paper presents the development of a lattice physics–to–core simulator two-step procedure for the rapid analysis of the Advanced High Temperature Reactor (AHTR). Lattice physics, reflector, and control blade models were developed from which cross-section libraries could be generated for a nodal core simulator. Few-group structures for the core simulator were also generated to account for the neutronic characteristics of AHTR. After developing the AHTR two-step procedure, cross-section libraries were generated using the SERPENT continuous-energy Monte Carlo code. These libraries were then used in the core simulator NESTLE to perform full-core calculations, which were in turn benchmarked against reference SERPENT full-core models. Benchmarking results showed reasonable accuracy of the developed two-step procedure but revealed an inherent inadequacy in the one-dimensional radial reflector model and showed a likely need for a greater number of energy groups than were used in this study.
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
Model-based, in-situ, non-destructive qualification and certification of parts made by autonomous additive manufacturing
To address the significant productivity challenges associated with the qualification and certification (Q&C) tasks of additively manufactured (AM) parts, which have traditionally relied on rigorous post‐build inspection and testing, we propose an integrated framework that combines model‐based qualification and certification (MBQ&C) with autonomous additive manufacturing (AAM). MBQ&C employs high‐fidelity predictive models, developed within the Integrated Computational Materials Engineering (ICME) paradigm, to simulate process–structure–property–performance relationships for assessing a part’s fitness for use. Since predictive models are commonly machine learning (ML)-based or reduced-order surrogates of validated physics models, they run efficiently, enabling timely inference. In parallel, the self-driving AAM utilises ML-based adaptive, closed‐loop control strategies to avoid, mitigate, or repair defects and anomalies during fabrication, thereby increasing the likelihood of producing acceptable parts. A key feature of the combined AAM-MBQ&C framework is that predictive models explicitly incorporate defects or anomalies that persist after the build, using instance-specific data captured via in-situ sensing. This customisation enables a build‐specific assessment of fitness for use, rather than relying on nominal or generic parameters. Such individualised evaluation provides a robust basis for Q&C-related acceptance decisions relating to each build. Additionally, the rapid solution capabilities of ML or reduced-order models enable the determination of a part’s suitability for service shortly after build completion. As the framework matures, it has the potential to substantially reduce reliance on conventional point‐design approaches—such as time‐consuming post‐build computed tomography scanning and costly destructive testing. Thus, the AAM-MBQ&C framework represents a transformative, scalable strategy for quality assurance of AM components, as parts produced within a stable, validated, and certified envelope can be certified with reduced testing. Key benefits include: (1) significant gains in Q&C productivity through efficient, model-centric assessment; (2) performance-based classification of defects into critical and non-critical categories; (3) the ability to predict potential deviations in the performance of parts affected by real-time, adaptive process control interventions relative to those produced under a certified process, and (4) the enabling of virtual Q&C for service environments that are difficult, hazardous, or impractical to access or reproduce experimentally. Collectively, these capabilities strengthen the business case for AM, particularly for high‐consequence and mission‐critical applications. Finally, although this work focuses on powder-based AM, the proposed techniques could be extended to AM processes employing alternative feedstock forms.
Gunasegaram, Dayalan↗
Synergy between phase transformation and domain switching in two morphotropic phase boundary ferroelectrics
We present that many applications of ferroic materials take advantage of the microstructural redistribution under an external stimulus. Despite extensive studies on the microstructural evolution during both domain switching and phase transformations of high-performance ferroelectrics near morphotropic phase boundaries (MPBs), the synergetic interactions between both leading factors remain unclear. Herein, we have illustrated and discerned the correlative response of phase transformation and domain switching in an archetypical piezoceramic of PbTiO 3 -BiScO 3 using a combination of in situ high-energy synchrotron x-ray diffraction and phase-field simulations. The direct structural evidence and domain development from simulations reveal a significant reversible orientation-dependent emerging phase transformation and enhanced domain switching. Increasingly populated polarization variants aligned with the applied electric field owing to this strong synergistic interaction play an important role in enhancing the piezoelectric performances of MPB ferroelectrics. Lastly, in addition to providing further insight into the microstructures of ferroelectrics, the present results have the potential to guide the design of high-performance materials.
36 MATERIALS SCIENCE↗
Energetic Substantiation of the Formation of Ytterbium Dimers in Single Forsterite Crystals
A structural computer simulation of ytterbium-containing forsterite crystals has been carried out. Atomistic simulation is performed using the GULP 4.1 software package (General Utility Lattice Program). Different mechanisms of ytterbium dissolution in forsterite crystals are considered, and the dissolution energies of isolated defects, as well as charged and neutral clusters of various configurations, are calculated. The results of the calculation manifest that the formation of ytterbium clusters with a magnesium vacancy gives a significant gain in the dissolution energy. The formation of neutral clusters (dimers) in the M1 site (Yb{sub Mg1}ν{sub Mg1}Yb{sub Mg1}) leads to an energy reduction by 1.7 eV compared with the statistical distribution of defects. As a result of simulation, it is shown the energetic substantiation of the formation of ytterbium dimers in forsterite crystals. A model of the most energetically favorable center in the M1 site is proposed—a dimer, consisting of a pair of trivalent ytterbium ions with a magnesium vacancy between them, forming a chain parallel to the crystallographic axis c.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Excess carrier concentration in silicon devices and wafers: How bulk properties are expected to accelerate light and elevated temperature degradation
Light and elevated temperature induced degradation (LeTID) is accelerated nearly linearly by the presence of excess carriers. It is therefore important to understand how excess carrier concentration (Δn) changes as a function of exposure conditions, materials properties, and sample structure. We simulate Δn as a function of wafer thickness and bulk minority carrier lifetime (τ) in solar cells and wafers using SCAPS and Quokka3. We also derive closed-form analytic expressions. For wafers, there is a near-linear relationship between Δn and τ or thickness, whereas for solar cells, Δn in the bulk may become limited by rear surface recombination. Thus, LeTID may progress more quickly in wafers than in cells, with a stronger dependence on τ. When comparing experiments, observed degradation rates must be corrected between samples or conditions to account for differences in Δn. This study demonstrates three tools to estimate the magnitude of such corrections, which can aid in the quantitative interpretation of LeTID data and performance predictions. Finally, while each tool yields similar results, there are advantages to each approach that must be weighed in terms of simplicity of inputs versus sophistication of treatment. Incomplete specification of back contact characteristics in commercial products is identified as an important contributor to uncertainty in expected LeTID rates.
36 MATERIALS SCIENCE↗
Development of a Green Parabolic Trough Collector
This report describes in detail a research project that assesses the potential of a parabolic trough solar collector with a lumber construction to meet ambitious performance, cost, and durability goals. Instead of exploring lumber as a general question for solar collectors, the project focuses on the design optimization, laboratory testing, outdoor testing, and economic modeling of a particular scale of parabolic trough, namely, the 6m aperture and 12m long module that has become the standard in the utility-scale power plant market. As will be appreciated in the report, it is also a scale that matches well the capabilities of lumber as a structural material and the commonly available cross sections. The design and its analysis extend far beyond traditional considerations for wooden structures in the built environment, and includes a computationally efficient coupled structural-optical simulation and the empirical characterization of joint stiffness at small deformations. Laboratory testing is used to characterize cyclic joint behavior, accelerated weathering, and to validate the simulation used as the basis for building a full-scale prototype. The construction and outdoor testing of this prototype is described. A total installed cost model of the collector is presented and the impact of the cost is seen in the context of a full plant techno-economic model. The results of this model in combination with the experience with the first prototype suggest that with improvements to the design and assembly process, this collector type has the potential to lower the levelized cost of heat for industrial solar steam plants used for process heating or cogeneration.
14 SOLAR ENERGY↗
Large-Scale, GPU-Enhanced DFTB Approaches for Probing Multi-Component Alloys
The major goals of the project are to develop and apply GPU-enhanced density functional theory tight binding (DFTB) calculations for efficient simulations of structural materials of alloy systems. The figure below depicts the GPU algorithmic developments on the left that will be carried out, and the solid-state structures on the right are representative of the complex alloys that can be computed with the GPU-enhanced DFTB approach. The methodology and tools developed in this project encompass accurate intermolecular potentials and GPU enhancements to the density functional tight binding (DFTB) approach for high-throughput ab initio molecular dynamics calculations of multi-component alloys at elevated temperatures. While classical molecular dynamics can handle hundreds of thousands of atoms, it cannot provide a first-principles based description of large, multi-component alloys at the predictive quantum level. At the other extreme, conventional Kohn-Sham DFT methods can probe the true quantum nature of chemical systems; however, these methods cannot tackle the large sizes relevant to these multi-component systems. The DFTB-based ab initio molecular dynamics approach (coupled with our in-house GPU capabilities for enhanced speed) used in this project provides a viable approach for probing these large systems at a quantum level of detail that is significantly faster than current first-principle methods Collectively, the capabilities developed in this project directly respond to DOE HBCU-OMI, AOI 2-1 initiatives by (1) enabling accurate and efficient predictions and (2) bringing a fundamental understanding of structural interactions in these complex systems at elevated temperatures.
20 FOSSIL-FUELED POWER PLANTS↗
Exotanium DOE SBIR Phase I Results Summary
Exotanium demonstrated this technology with the Idaho National Laboratory’s MASTODON application, a Multiphysics environment designed to run typical high-performance computing (HPC) simulations for structural dynamics, seismic analysis, and risk assessment. The MASTODON application was packaged into a container using Docker, Deployed on Amazon ECS, and managed through a custom Scale-Out Compute on AWS (SOCA) implementation.
97 MATHEMATICS AND COMPUTING↗
Modeling & Simulation of Additively Manufactured Lattice Structures to Support Component Qualification.
Abstract not provided.
Swanson, Andrew↗