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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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At least 361 records · Page 20

In Situ/Operando Probing of Dynamic Phase Structures of Alumina‐Supported Ultrasmall Copper‐Gold Alloy Nanoparticles Under Reaction Conditions

Abstract The ability to control phase structures and surface sites of ultrasmall alloy nanoparticles under reaction conditions is essential for preparing catalysts by design. This is, however, challenging due to limited understanding of the atomic‐scale phases and their correlation with the ensemble‐averaged structures and activities of catalysts during catalytic reactions. We reveal here a dynamic structural stability of alumina‐supported ultrasmall and equiatomic copper‐gold alloy nanoparticles under reaction conditions as a model system in the in situ/operando study. In situ atomic‐scale morphological tracking under oxygen reveals temperature‐dependent dynamic crystalline‐amorphous dual‐phase structures, showing dynamic stability over an elevated temperature range. This atomic‐scale dynamic phase stability coincides with a “conversion plateau” observed for carbon monoxide oxidation on the catalyst. It is substantiated by the stable lattice ordering/disordering structures and surface sites with oscillatory characteristics shown by operando ensemble‐average structural tracking of the catalyst during the oxidation reaction. The understanding of the atomic‐scale dynamic phase structures in correlation with the ensemble‐average dynamic ordering/disordering phase structures and surface sites provides fresh insights into the unique synergy of the supported alloy nanoparticles. This understanding has implications for the design and structural tuning of active and stable ultrasmall alloy catalysts under elevated temperatures.

Chemistry↗

Effect of cellulose reducing ends and primary hydroxyl groups modifications on cellulose-cellulase interactions and cellulose hydrolysis

Cellulose reducing ends are believed to play a vital role in the cellulose recalcitrance to enzymatic conversion. However, their role in insoluble cellulose accessibility and hydrolysis is not clear. Thus, in this study, reducing ends of insoluble cellulose derived from various sources were modified by applying reducing and/or oxidizing agents. Here, the effects of cellulose reducing ends modification on cellulose reducing ends, cellulose structure, and cellulose accessibility to cellulase were evaluated along with the impact on cellulose hydrolysis with complete as well purified cellulase components. Sodium borohydride (NaBH 4 ) reduction and sodium chlorite-acetic acid (SC/AA) oxidation were able to modify more than 90% and 60% of the reducing ends, respectively, while the bicinchoninic acid (BCA) reagent applied for various cycles oxidized cellulose reducing ends to various extents. X-ray diffractograms of the treated solids showed that these treatments did not change the cellulose crystalline structure and the change in crystallinity index was insignificant. Surprisingly, it was found that the cellulose reducing ends modification, either through selective NaBH 4 reduction or BCA oxidation, had a negligible impact on cellulose accessibility as well on cellulose hydrolysis rates or final conversions with complete cellulase at loadings as low as 0.5 mg protein/g cellulose. In fact, in contrast to what is traditionally believed, modifications of cellulose reducing ends by these two methods had no apparent impact on cellulose conversion with purified cellulase components and their synergy. However, SC/AA oxidation resulted in significant drop in cellulose conversion (10%–50%) with complete as well purified cellulase components. Nonetheless, further research revealed that the cause for drop in cellulose conversion for the SC/AA oxidation case was due to primary hydroxyl groups (PHGs) oxidation and not the oxidation of reducing ends. Furthermore, it was found that the PHGs modification affects cellulose accessibility and slows the cellulase uptake as well resulting in significant drop in cellulose conversions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Supramolecular Assemblies for Electronic Materials

This study presents a synergy between organic electronics and supramolecular chemistry, in which a host–guest complex is designed to function as an efficacious electronic material. Specifically, the noncovalent recognition of a fullerene, phenyl-C 61 -butyric acid methyl ester (PC 61 BM), by an alternating perylene diimide (P)-bithiophene (B) conjugated macrocycle (PBPB) results in a greater than five-fold enhancement in electron mobility, relative to the macrocycle alone. Characterization and quantification of the binding of fullerenes by host PBPB is provided alongside evidence for intermolecular electronic communication within the host–guest complexes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Structure- and Interaction-Based Design of Anti-SARS-CoV-2 Aptamers

Aptamer selection against novel infections is a complicated and time-consuming approach. Synergy can be achieved by using computational methods together with experimental procedures. In this study, we aim to develop a reliable methodology for a rational aptamer in silico et vitro design. The new approach combines multiple steps: (1) Molecular design, based on screening in a DNA aptamer library and directed mutagenesis to fit the protein tertiary structure; (2) 3D molecular modeling of the target; (3) Molecular docking of an aptamer with the protein; (4) Molecular dynamics (MD) simulations of the complexes; (5) Quantum-mechanical (QM) evaluation of the interactions between aptamer and target with further analysis; (6) Experimental verification at each cycle for structure and binding affinity by using small-angle X-ray scattering, cytometry, and fluorescence polarization. By using a new iterative design procedure, structure- and interaction-based drug design (SIBDD), a highly specific aptamer to the receptor-binding domain of the SARS-CoV-2 spike protein, was developed and validated. The SIBDD approach enhances speed of the high-affinity aptamers development from scratch, using a target protein structure. The method could be used to improve existing aptamers for stronger binding. This approach brings to an advanced level the development of novel affinity probes, functional nucleic acids. It offers a blueprint for the straightforward design of targeting molecules for new pathogen agents and emerging variants.

60 APPLIED LIFE SCIENCES↗

Electrolyte Engineering Stabilizes Photoanodes Decorated with Molecular Catalysts

Molecular catalysts are promising oxygen evolution promoters in conjunction with photoanodes for solar water splitting. Maintaining the stability of both photoabsorber and cocatalyst is still a prime challenge, with many efforts tackling this issue through sophisticated material designs. Such approaches often mask the importance of the electrode-electrolyte interface and overlook easily tunable system parameters, such as the electrolyte environment, to improve efficiency. We provide a systematic study on the activity-stability relationship of a prominent Fe 2 O 3 photoanode modified with Ir molecular catalysts using in situ mass spectroscopy. After gaining detailed insights into the dissolution behavior of the Ir cocatalyst, a comprehensive pH study is conducted to probe the impact of the electrolyte on the performance. An inverse trend in Fe and Ir stability is found, with the best activity-stability synergy obtained at pH 9.7. The results bring awareness to the overall photostability and electrolyte engineering when advancing catalysts for solar water splitting.

14 SOLAR ENERGY↗

Manipulation of Scattering Spectra with Topology of Light and Matter

Structured lights, including beams carrying spin and orbital angular momenta, radially and azimuthally polarized vector beams, as well as spatiotemporal optical vortices, have attracted significant interest due to their unique amplitude, phase front, polarization, and temporal structures, enabling a variety of applications in optical and quantum communications, micromanipulation, and super-resolution imaging. In parallel, structured optical materials, metamaterials, and metasurfaces consisting of engineered unit cells—meta-atoms, opened new avenues for manipulating the flow of light and optical sensing. While several studies explored structured light effects on the individual meta-atoms, their shapes are largely limited to simple spherical geometries. However, the synergy of the structured light and complex-shaped meta-atoms has not been fully explored. Here, in this paper, the role of the helical wavefront of Laguerre–Gaussian beams in the excitation and suppression of higher-order resonant modes inside all-dielectric meta-atoms of various shapes, aspect ratios, and orientations, is demonstrated and the excitation of various multipolar moments that are not accessible via unstructured light illumination is predicted. The presented study elucidates the role of the complex phase distribution of the incident light in shape-dependent resonant scattering, which is of utmost importance in a wide spectrum of applications ranging from remote sensing to spectroscopy.

42 ENGINEERING↗

Exploding Bridgewire (EBW) Detonators: An Example of Synergistic Multiphysics

Exploding bridgewire (EBW) detonators are highly temporally reproducible explosive devices that require the rapid discharge of a high‐voltage capacitance to operate and so are immune to most of the accidental hazards associated with traditional electric detonators. They have been demonstrated to be safe enough for use in high‐consequence explosive applications. Despite continued use for over 82 years, understanding the exact mechanism of operation has remained elusive. Various researchers have ascribed either deflagration‐to‐detonation (DDT) or shock‐to‐detonation (SDT) phenomena observed in other explosive events to explain the science behind the successful engineering; however, a rigorous justification has been absent. Previously, we have demonstrated a complex interaction in EBW detonators between large electrical currents, non‐equilibrium thermodynamic material states, plasma physics, powder compaction phenomena, shock physics, photochemistry, and rapid conventional explosive chemical reaction processes. Specifically, we have made progress in understanding the complex multiphysics that operates in these detonators and demonstrating that it is a serendipitous synergy between UV light emitted from the arc formed as the bridge is electrically exploded and the accompanying short‐duration shock transmitted into the explosive powder bed that allows these devices to function at practical capacitor sizes and charge voltages. This insight not only places the topic on a firmer scientific footing but potentially enables new approaches to safe detonator design.

36 MATERIALS SCIENCE↗

Strangely attractive: Collaboration and feedback in the field of molecular magnetism

The fluid synergy between experimentalists and theoreticians has, for decades, led to a deeper understanding of the processes that govern single-molecule magnets. This approach has allowed for the establishment of proven design criteria for the control of magnetic properties through molecular architecture and the development of new magnetic measurement techniques and innovative computational methodologies. Here, we give an account of the experimental and theoretical joint endeavor carried out as part of the synthesis group led by David Mills and the computational/theoretical team led by Nicholas Chilton, together with colleagues in synthetic f-element chemistry and magnetism at the University of Manchester. In addition, we provide a personal perspective on collaborative work in molecular magnetism and how such collaborations are essential for advancing the field further.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

The basics of quantum computing for chemists

The rapid and successful strides in quantum chemistry in the past decades can be largely credited to a conspicuous synergy between theoretical and computational advancements. However, the architectural computer archetype that enabled such a progress is approaching a state of more stagnant development. One of the most promising technological avenues for the continuing progress of quantum chemistry is the emerging quantum computing paradigm. This revolutionary proposal comes with several challenges, which span a wide array of disciplines. In chemistry, it implies, among other things, a need to reformulate some of its long established cornerstones in order to adjust to the operational demands and constraints of quantum computers. Due to its relatively recent emergence, much of quantum computing may still seem fairly nebulous and largely unknown to most chemists. It is in this context that here we review and illustrate the basic aspects of quantum information and their relation to quantum computing insofar as enabling simulations of quantum chemistry. As a result, we consider some of the most relevant developments in light of these aspects and discuss the current landscape when of relevance to quantum chemical simulations in quantum computers.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Nanostructured Conductive Metal Organic Frameworks for Sustainable Low Charge Overpotentials in Li–Air Batteries

Lithium-oxygen batteries are among the most attractive alternatives for future electrified transportation. However, their practical application is hindered by many obstacles. Due to the insulating nature of Li 2 O 2 product and the slow kinetics of reactions, attaining sustainable low charge overpotentials at high rates becomes a challenge resulting in the battery's early failure and low round trip efficiency. Herein, outstanding characteristics are discovered of a conductive metal organic framework (c-MOF) that promotes the growth of nanocrystalline Li 2 O 2 with amorphous regions. This provides a platform for the continuous growth of Li 2 O 2 units away from framework, enabling a fast discharge at high current rates. Moreover, the Li 2 O 2 structure works in synergy with the redox mediator (RM). The conductivity of the amorphous regions of the Li 2 O 2 allows the RM to act directly on the Li 2 O 2 surface instead of catalyst edges and then transport through the electrolyte to the Li 2 O 2 surface. This direct charge transfer enables a small charge potential of <3.7 V under high current densities (1-2 A g -1 ) sustained for a long cycle life (100-300 cycles) for large capacities (1000-2000 mAh g -1 ). These results open a new direction for utilizing c-MOFs towards advanced energy storage systems.

25 ENERGY STORAGE↗

Anionic‐Based Layered Oxide Cathodes with High Electrochemical Performance through Dual‐Site Substitutions for Sodium‐Ion Batteries

Mn-rich layered oxide cathodes with anionic redox promise high energy density for sodium-ion batteries (SIBs) due to ultra-high capacity derived from both Mn and O redox couples. Nevertheless, instability of the reactions that lead to poor electrochemical stability hinders the cathodes from practical applications. Here, the Al and Zn dual-site substitution strategy is proposed to enhance electrochemical performance. Here, the designed cathode, Na 0.73 Zn 0.03 Li 0.25 Mn 0.76 Al 0.01 O 2 (AlZn), delivers a high discharge capacity of 242 mAh g −1 with an impressive rate capability (162 mAh g −1 at 1000 mA g −1 ) and excellent capacity retention (89.69% over 150 cycles). In addition, full-cell SIB based on AlZn coupled with hard carbon exhibits a high energy density of 317 Wh kg −1 (based on both cathode and anode mass) and a reasonable capacity retention of 80.8% after 250 cycles. Revealed by advanced investigations, the synergy of robust Al–O in TM layers and O–Zn–O pillars in Na layers helps alleviate severe inactive spinel/rock-salt phase transformation and intragranular cracks in the AlZn cathode. This consequently leads to greatly enhanced electrochemical performance over the pristine cathode. This work provides insight into improving electrochemical properties of anionic-redox-based layered oxides by Al/Zn co-substitutions toward high-energy SIBs.

25 ENERGY STORAGE↗

Integrated Micro‐Scale Concentrating Photovoltaics: A Scalable Path Toward High‐Efficiency, Low‐Cost Solar Power

The global energy market is seeing increases in the electricity demand of a couple of percentage points annually. The photovoltaic (PV) industry is also growing rapidly every year. One of the PV technologies is concentrator photovoltaics (CPV). CPV uses high‐efficiency multijunction solar cells and optics to concentrate sunlight, thereby significantly reducing the amount of semiconductor material needed. Yet, due to the high upfont manufacturing cost of CPV, it currently does not offer a competitive price against silicon PV. With this a new branch is introduced to the industry, micro‐CPV, which can be broadly explained as the miniaturization of the solar cells and optical components. The motivation for micro‐CPV is lowering the cost by decreasing the material volume and enabling new system architectures and high‐throughput manufacturing methods, while still maintaining high electrical efficiencies, taking advantage of a lower thermal load, shorter optical paths, lower resistive losses, and lower material volumes. Herein, a comprehensive review of the technological advances is presented, key synergies between micro‐CPV and other industries sharing similar challenges are identified, exemplified by micro‐light emitting diodes display manufacturing. New assembly process development in these industries will facilitate commercial adoption of micro‐CPV with continued miniaturization while driving down the cost.

Jost, Norman↗

Wind power costs driven by innovation and experience with further reductions on the horizon

The costs of wind power have declined to levels on par with or below those of conventional sources in many parts of the world. Wind power has become one of the fastest-growing sources of new electricity generation. We take stock of wind power cost evolution over the past 20 years, review methodologies commonly used for cost assessment, discuss the potential for continued cost reduction, and identify anticipated cost and value drivers. Our scope includes both onshore and offshore wind technologies. We draw from a vast body of literature on these topics to highlight key trends, approaches, and limitations. Furthermore, we discuss strategies for wind power assets to enhance their marginal economic value to the broader power system and consumers. We identify a myriad of factors that are expected to influence the future cost and value of wind power, including siting, project scale, turbine size, operational synergies, commodity prices, advancements in turbine technologies, enhanced management of the wind resource, and novel control technologies that provide value for the electricity grid. Because the common methods for forecasting future costs each have their own strengths and weaknesses, we find the best insights are elicited from a combination of methods. Overall, researchers and analysts anticipate further sizable cost reductions for onshore and offshore wind. Midrange forecasts for levelized cost of energy in 2050 are generally between $20 and $30/MWh for onshore wind and $40 and $60/MWh for offshore wind, a reduction to approximately half of today's levels. Optimistic forecasts anticipate these levels as early as 2030.

17 WIND ENERGY↗

Highly accelerated life testing (HALT): A review from a statistical perspective

Despite its use in one form or another for at least four decades, HALT and related techniques [e.g., highly accelerated-stress screening (HASS) and stress audits (HASA)] are not well understood within the statistical community and remain controversial. This largely reflects a conflict in motivation between engineers, testing under harsh conditions to discover and eliminate failure modes, and statisticians, taking a more cautious approach to develop quantitative estimates of parameters such as mean time between failures (MTBF). Here, this review article will clarify HALT concepts and methods and explain where it fits within the universe of methods that involve the application of accelerating factors to compress the time required to evaluate or enhance product reliability. A major distinction is between methods such as HALT, a high-stress test-analyze-fix-test iterative process directed at improving reliability by discovering and fixing weak points in a design, and quantitative accelerated life testing (QALT), whose goal is the estimation of product life for a fixed design. We discuss methods such as physics of failure that offer some hope of bridging the gap between the qualitative nature of HALT, and purely quantitative statistical methods. We present a variety of engineering applications of HALT including metal fatigue, piping and pressure vessels, structural damage, radiation damage, and rotating machinery. We also discuss potential synergies between HALT and QALT, such as rapid identification, through HALT, of failure modes requiring quantitative analysis. For further study, extensive references to the applicable literature are provided as well as an appendix that describes related methods.

97 MATHEMATICS AND COMPUTING↗

Earth-catalyzed detection of magnetic inelastic dark matter with photons in large underground detectors

Inelastic dark matter with moderate splittings, $\mathcal{O}$ (few to 150) keV, can upscatter to an excited state in the Earth, with the excited state subsequently decaying, leaving a distinctive monoenergetic photon signal in large underground detectors. The photon signal can exhibit sidereal-daily modulation, providing excellent separation from backgrounds. Using a detailed numerical simulation, we examine this process as a search strategy for magnetic inelastic dark matter with the dark matter mass near the weak scale, where the upscatter to the excited state and decay proceed through the same magnetic dipole transition operator. At lower inelastic splittings, the scattering is dominated by moderate mass elements in the Earth with high spin, especially 27 Al, while at larger splittings, 56 Fe becomes the dominant target. We show that the proposed large volume gaseous detector CYGNUS will have excellent sensitivity to this signal. Xenon detectors also provide excellent sensitivity through the inelastic nuclear recoil signal, and if a future signal is seen, we show that the synergy among both types of detection can provide strong evidence for magnetic inelastic dark matter. In the course we have calculated nuclear response functions for elements relevant for scattering in the Earth, which are publicly available on GitHub.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Sleptonic SUSY: from UV framework to IR phenomenology

We study an attractive scenario, “Sleptonic SUSY”, which reconciles the 125 GeV Higgs scalar and the non-observation of superpartners thus far with potentially pivotal roles for slepton phenomenology: providing viable ongoing targets for LHC discovery, incorporating a co-annihilation partner for detectable thermal relic dark matter, and capable of mediating the potential muon g – 2 anomaly. This is accomplished by a modestly hierarchical spectrum, with sub-TeV sleptons and electroweakinos and with multi-TeV masses for the other new states. We study new elements in the UV MSSM realization of Sleptonic SUSY based on higher-dimensional sequestering and the synergy between the resulting gaugino-mediation, hypercharge D-term mediation and Higgs-mediation of SUSY-breaking, so as to more fully capture the range of possibilities. This framework stands out by harmoniously solving the flavor, CP and μ – Bμ problems of the supersymmetric paradigm. We discuss its extension to orbifold GUTs, including gauge-coupling and b-tau unification. We also develop a non-minimal model with extra Higgs fields, in which the electroweak vacuum is more readily cosmologically stable against decay to a charge-breaking vacuum, allowing a broader range of sleptonic spectra than in the MSSM alone. We survey the rich set of signals possible at the LHC and future colliders, covering both R-parity conservation and violation, as well as for dark matter detection. While the multi-TeV squarks imply a Little Hierarchy Problem, intriguingly, small changes in parameter space to improve naturalness result in dramatic phase transitions to either electroweak-preservation or charge-breaking. In a Multiverse setting, the modest unnaturalness may then be explained by the “principle of living dangerously”.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

GeoSoilEnviroCARS (Sector 13) at the Advanced Photon Source: a comprehensive synchrotron radiation facility for Earth science research at ambient and extreme conditions

GeoSoilEnviroCARS (GSECARS) is a comprehensive analytical laboratory for Earth and environmental science research using X-ray beams from the Advanced Photon Source, Argonne National Laboratory. State-of-the-art instruments are available for (1) high-pressure/high- or low-temperature diffraction, total scattering, and spectroscopy (Brillouin, Raman, and VIS-IR) using the laser heated diamond anvil cell (DAC); (2) high-pressure/high-temperature diffraction, scattering, and imaging as well as acoustic emission (AE) and ultrasonics using the large-volume press (LVP); (3) powder, single crystal, and surface/interface diffraction; (4) X-ray absorption fine structure spectroscopy; (5) X-ray fluorescence microprobe analysis; and (6) microtomography. As shown here, experiments are facilitated by senior level staff who collaborate on all aspects of the analytical work including experiment design, sample preparation, data collection, data interpretation, and publication preparation. Both technical and scientific synergies occur as a result of the intimate association of the various techniques and scientists experienced in the applications of synchrotron radiation to Earth, environmental, and planetary science problems. The facility includes state-of-the-art instrumentation designed and built in-house, including custom X-ray optics, online and offline laser-based systems, specialized sample environments and positioning systems, as well as pixel-array and multi-crystal energy dispersive X-ray detectors, which are available to be shared among the experimental stations.

36 MATERIALS SCIENCE↗