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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
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Polariton creation in coupled cavity arrays with spectrally disordered emitters

Abstract Integrated photonics has been a promising platform for analog quantum simulation of condensed matter phenomena in strongly correlated systems. To that end, we explore the implementation of all-photonic quantum simulators in coupled cavity arrays with integrated ensembles of spectrally disordered emitters. Our model is reflective of color center ensembles integrated into photonic crystal cavity arrays. Using the Quantum Master equation and the Effective Hamiltonian approaches, we study energy band formation and wavefunction properties in the open quantum Tavis–Cummings–Hubbard framework. We find conditions for polariton creation and (de)localization under experimentally relevant values of disorder in emitter frequencies, cavity resonance frequencies, and emitter-cavity coupling rates. To quantify these properties, we introduce two metrics, the polaritonic and nodal participation ratios, that characterize the light-matter hybridization and the node delocalization of the wavefunction, respectively. These new metrics combined with the Effective Hamiltonian approach prove to be a powerful toolbox for cavity quantum electrodynamical engineering of solid-state systems.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2019

Functional Gene Array-Based Ultrasensitive and Quantitative Detection of Microbial Populations in Complex Communities

ABSTRACT While functional gene arrays (FGAs) have greatly expanded our understanding of complex microbial systems, specificity, sensitivity, and quantitation challenges remain. We developed a new generation of FGA, GeoChip 5.0, using the Agilent platform. Two formats were created, a smaller format (GeoChip 5.0S), primarily covering carbon-, nitrogen-, sulfur-, and phosphorus-cycling genes and others providing ecological services, and a larger format (GeoChip 5.0M) containing the functional categories involved in biogeochemical cycling of C, N, S, and P and various metals, stress response, microbial defense, electron transport, plant growth promotion, virulence, gyrB , and fungus-, protozoan-, and virus-specific genes. GeoChip 5.0M contains 161,961 oligonucleotide probes covering >365,000 genes of 1,447 gene families from broad, functionally divergent taxonomic groups, including bacteria (2,721 genera), archaea (101 genera), fungi (297 genera), protists (219 genera), and viruses (167 genera), mainly phages. Computational and experimental evaluation indicated that designed probes were highly specific and could detect as little as 0.05 ng of pure culture DNAs within a background of 1 μg community DNA (equivalent to 0.005% of the population). Additionally, strong quantitative linear relationships were observed between signal intensity and amount of pure genomic (∼99% of probes detected; r > 0.9) or soil (∼97%; r > 0.9) DNAs. Application of the GeoChip to a contaminated groundwater microbial community indicated that environmental contaminants (primarily heavy metals) had significant impacts on the biodiversity of the communities. This is the most comprehensive FGA to date, capable of directly linking microbial genes/populations to ecosystem functions. IMPORTANCE The rapid development of metagenomic technologies, including microarrays, over the past decade has greatly expanded our understanding of complex microbial systems. However, because of the ever-expanding number of novel microbial sequences discovered each year, developing a microarray that is representative of real microbial communities, is specific and sensitive, and provides quantitative information remains a challenge. The newly developed GeoChip 5.0 is the most comprehensive microarray available to date for examining the functional capabilities of microbial communities important to biogeochemistry, ecology, environmental sciences, and human health. The GeoChip 5 is highly specific, sensitive, and quantitative based on both computational and experimental assays. Use of the array on a contaminated groundwater sample provided novel insights on the impacts of environmental contaminants on groundwater microbial communities.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Coupled surface plasmon–phonon polariton nanocavity arrays for enhanced mid-infrared absorption

Abstract Resonant optical cavities are essential components in mid-infrared applications. However, typical film-type cavities require multilayer stacks with a micron-thick spacer due to mid-infrared wavelengths, and their performance is limited by narrow frequency tunability and angular sensitivity. We propose and experimentally demonstrate the subwavelength-scale (≈ λ 0 /150) resonant nanocavity arrays that enhance the absorption spectrum of the device in the mid-infrared (10–12 microns) via excitation of coupled surface plasmon–phonon polaritons. The proposed metal–insulator–polar dielectric (gold–silicon–silicon carbide) structure supports a guided mode of the coupled surface polaritons in the lateral direction while vertically confining the mid-infrared wave within the 80 nm thick dielectric spacer. In particular, the subwavelength-scale (≈ λ 0 /10) gratings are imposed to form Fabry–Pérot cavity arrays displaying angle-insensitive and frequency-tunable absorption of up to 80% of the optical power in the mid-infrared. Our work should benefit diverse mid-infrared applications and novel designs of polariton-based photonic devices.

42 ENGINEERING↗
DOE OSTI2021

Using the “Inner” Array Boundary with KENO-VI [Slides]

Topics include: SGGP Array definition basics, what is meant by the "Inner" Boundary of an array, a critical experiment with flux filter, and NRC verification of criticality calculations with UNF-ST&DARDS.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2022

PARA: A New Platform for the Rapid Assembly of gRNA Arrays for Multiplexed CRISPR Technologies

Multiplexed CRISPR technologies have great potential for pathway engineering and genome editing. However, their applications are constrained by complex, laborious and time-consuming cloning steps. In this research, we developed a novel method, PARA, which allows for the one-step assembly of multiple guide RNAs (gRNAs) into a CRISPR vector with up to 18 gRNAs. Here, we demonstrate that PARA is capable of the efficient assembly of transfer RNA/Csy4/ribozyme-based gRNA arrays. To aid in this process and to streamline vector construction, we developed a user-friendly PARAweb tool for designing PCR primers and component DNA parts and simulating assembled gRNA arrays and vector sequences.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2019

Design, Fabrication, and Characterization of a Piezoelectric AFM Cantilever Array

Atomic force microscope (AFM) is a powerful instrument, which has been successfully employed in a myriad of applications from imaging to lithography, over the last decades. Despite its widespread use, low throughput of the AFM remains one of its major limitations along with slow scan rates in tapping mode. In this work, we propose a microfabricated cantilever array composed of five cantilevers, each equipped with onchip piezoelectric displacement sensors and an actuator for parallel imaging in tapping mode. The cantilevers are designed to have separate resonance frequencies in order to effectively minimize the vibrational coupling. The measured resonance frequencies range from 85.34 kHz to 107.78 kHz, and more than 5 kHz resonant frequency separation is achieved in the neighboring cantilevers. Vibrational coupling is mitigated by over two orders of magnitude compared to arrays with identical cantilevers. The common feedthrough problem in this type of active system is addressed by configuring the displacement sensors differentially. Finally, one of the cantilevers in the arrayis successfully employed for tapping mode AFM imaging.

42 ENGINEERING↗
DOE OSTI2019

Highly Uniform Resistive Switching in HfO 2 Films Embedded with Ordered Metal Nanoisland Arrays

Memristors enter a critical developmental stage where emerging large-scale integration methods face major challenges with severe switching instabilities in the oxide layer. In this work, the superior uniformity is achieved within HfO 2 films by embedding highly ordered metal nanoisland (NI) arrays. Embedded films exhibit a significant reduction in both SET and RESET while displaying enhanced uniformity in operating voltages and resistance states. This behavior is attributed to the concentration of electric fields along Pt and Ti NIs and their interactions with the surrounding oxide film matrix environment, which induce separate and distinct filamentary formation mechanisms that affect the stability. A method is reported to further optimize the uniformity of the SET voltage by translating the NI array position down the film-thickness dimension towards the bottom electrode. A comparison of the density and distribution of the oxygen vacancies responsible for the formation/dissolution of conducting filaments is made via combined electrostatic force microscopy and conductive atomic force microscopy (c-AFM) studies. Finally, complete observation of the morphological evolution of conducting filaments produced by Pt and Ti is enabled by 3D c-AFM nanotomography and cross-sectional scanning transmission electron microscopy–energy dispersive spectroscopy to provide direct correlations between NI-oxide interactions and overall switching performance.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Two‐Dimensional Arrays of Transition Metal Nitride Nanocrystals

Abstract The synthesis of low‐dimensional transition metal nitride (TMN) nanomaterials is developing rapidly, as their fundamental properties, such as high electrical conductivity, lead to many important applications. However, TMN nanostructures synthesized by traditional strategies do not allow for maximum conductivity and accessibility of active sites simultaneously, which is a crucial factor for many applications in plasmonics, energy storage, sensing, and so on. Unique interconnected two‐dimensional (2D) arrays of few‐nanometer TMN nanocrystals not only having electronic conductivity in‐plane, but also allowing transport of ions and electrolyte through the porous nanosheets, which are obtained by topochemical synthesis on the surface of a salt template, are reported. As a demonstration of their application in a lithium–sulfur battery, it is shown that 2D arrays of several nitrides can achieve a high initial capacity of >1000 mAh g −1 at 0.2 C and only about 13% degradation over 1000 cycles at 1 C under a high areal sulfur loading (>5 mg cm −2 ).

Xiao, Xu↗
DOE OSTI2025

Large‐Scale 2D Perovskite Nanocrystals Photodetector Array via Ultrasonic Spray Synthesis

Abstract 2D perovskite (PVSK) single crystals have received significant attention due to their unique optical and optoelectronic properties. However, current synthesis methods face limitations, particularly in large‐area fabrication, which remain critical barriers to practical applications. In this study, the synthesis of red/green/purple‐blue‐colored 2D PVSK nanocrystals over a large area (4‐inch wafer) and the fabrication of high‐performance photodetector arrays are presented via a facile yet efficient spray‐coating approach with a liquid‐bridge transport effect. The photodetector array achieves 100% working yield, high photo‐responsivity (1.5 × 10 6 A W −1 ) and specific‐detectivity (1.1 × 10 16 Jones) with competitive photomapping characteristics. An intelligent vision system for automatic shape recognition is further demonstrated with a recognition rate exceeding 90%. This study provides significant advances in the scalable synthesis of nanoscale 2D PVSK crystals, their integration into large‐area optoelectronic devices, and their potential use in artificial‐intelligence systems.

Lee, Yoon Ho [Davidson School of Chemical Engineer↗
DOE OSTI2021

Facilitating Large‐Scale Snow Shedding from In‐Field Solar Arrays using Icephobic Surfaces with Low‐Interfacial Toughness

Abstract Large‐scale accrual of snow and ice on solar arrays in northern latitudes can cause significant power generation losses during winter. Depending on environmental conditions, snow can encompass a wide range in physical characteristics from dry snow (modulus ≈100 kPa and density ≈0.1 g cm −3 ) to bulk ice (modulus ≈8 GPa and density ≈0.9 g cm −3 ). This variation in snow morphology has made the development of a passive, broad‐spectrum, snow and ice‐shedding surface challenging. Here, the authors develop one of the first surfaces that simultaneously possesses both low‐interfacial strength ( τ˄ ice < 50 kPa) and toughness (Γ ice < 0.5 J m −2 ) with ice. These surfaces, fabricated via the addition of mobile polymer chains/oils to a thin polymeric coating, require extremely low detachment forces for ice, enabling its passive shedding at virtually any accretion length scale. Preliminary evidence that the new surfaces can shed different forms of snow and ice from field‐deployed solar arrays, over a range of subzero temperatures for several weeks, leading to significant increases in power generation is provided. The optically transparent surfaces are easily scalable and can be widely deployed by the solar industry in areas that see persistent snow. Other applications include automotive windshields, LIDAR covers for autonomous vehicles, and cold climate optical sensors.

Dhyani, Abhishek↗
DOE OSTI2026

Toward Fully Soft and Multifunctional Shape Sensing via Optical Waveguide Arrays

For soft bodies, surface deformation and pressure provide proprioceptive and exteroceptive information, including body configuration, body compliance, and external forces. We develop a sheet sensor with a fully soft sensing surface that provides surface shape reconstruction using optical waveguide arrays. The waveguides are fabricated to achieve a tunable linear response to bi‐directional bending curvature, and the waveguide arrays are configured to differentiate between ambiguous shapes. We characterize the waveguide performance, relating curvature sensitivity to the core's surface roughness. Synergy of waveguide responses reduces the number of sensing elements required and achieves damage resilience. Using waveguide sensitivity to pressure, we also demonstrate feasibility for exteroception. We demonstrate the multifunctional sensing capability by wrapping the sheet around an upper arm, showcasing joint motion and external force sensing. Integrated into or applied onto surfaces of robotic or living systems, this design can be implemented in applications such as virtual reality, teleoperation, physical therapy, and soft robotics.

Yu, Qifan [Department of Mechanical Engineering Ma↗
DOE OSTI2020

Atomically Dispersed Nickel(I) on an Alloy‐Encapsulated Nitrogen‐Doped Carbon Nanotube Array for High‐Performance Electrochemical CO 2 Reduction Reaction

Abstract Single‐atom catalysts (SACs) show great promise for electrochemical CO 2 reduction reaction (CRR), but the low density of active sites and the poor electrical conduction and mass transport of the single‐atom electrode greatly limit their performance. Herein, we prepared a nickel single‐atom electrode consisting of isolated, high‐density and low‐valent nickel(I) sites anchored on a self‐standing N‐doped carbon nanotube array with nickel–copper alloy encapsulation on a carbon‐fiber paper. The combination of single‐atom nickel(I) sites and self‐standing array structure gives rise to an excellent electrocatalytic CO 2 reduction performance. The introduction of copper tunes the d‐band electron configuration and enhances the adsorption of hydrogen, which impedes the hydrogen evolution reaction. The single‐nickel‐atom electrode exhibits a specific current density of −32.87 mA cm −2 and turnover frequency of 1962 h −1 at a mild overpotential of 620 mV for CO formation with 97 % Faradic efficiency.

Zhang, Tianyu↗
DOE OSTI2022

Grassland productivity responds unexpectedly to dynamic light and soil water environments induced by photovoltaic arrays

Abstract Agrivoltaic (AV) systems are designed to coproduce photovoltaic (PV) energy on lands simultaneously supporting agriculture (food/forage production). PV infrastructure in agroecosystems alters resources critical for plant growth, and water‐limited agroecosystems such as grasslands are likely to be particularly sensitive to the unique spatial and temporal patterns of incident sunlight and soil water inherent within AV systems. However, the impact of resource alteration on forage production, the primary ecosystem service from managed grasslands, is poorly resolved. Here, we evaluated seasonal patterns of soil moisture (SM) and diurnal variation in incident sunlight (photosynthetic photon flux density [PPFD]) in a single‐axis‐tracking AV system established in a formerly managed semiarid C 3 grassland in Colorado. Our goals were to (1) quantify dynamic patterns of PPFD and SM within a 1.2 MW PV array in a perennial grassland, and (2) determine how aboveground net primary production (ANPP) and photosynthetic parameters responded to the resource patterns created by the PV array. We hypothesized that spatial variability in ANPP would be strongly related to SM patterns, typical of most grasslands. We measured significant reductions in ANPP directly beneath PV panels, where SM and PPFD were both low. However, in locations with significantly increased SM from the shedding and redistribution of precipitation by PV panels, ANPP was not increased. Instead, ANPP was greatest in locations where plants were shaded in the afternoon but received high levels of PPFD in the morning hours, when air temperatures and vapor pressure deficits were relatively low. Thus, contrary to expectations, we found relatively weak relationships between SM and ANPP despite significant spatial variability in both. Further, there was little evidence that light‐saturated photosynthesis ( A sat ) and quantum yield of CO 2 assimilation (ϕCO 2 ) differed for plants growing directly beneath (lowest PPFD) versus between (highest PPFD) PV panels. Overall, the AV system established in this semiarid managed grassland did not alter patterns of ANPP in ways predictable from past studies of controls of ANPP in open grasslands. However, our results suggest that the diurnal timing of low versus high periods of PPFD incident on plants is an important determinant of productivity patterns in grasslands.

14 SOLAR ENERGY↗
DOE OSTI2020

Enhancement of Magneto‐Mechanical Actuation of Micropillar Arrays by Anisotropic Stress Distribution

Abstract Magnetically active shape‐reconfigurable microarrays undergo programmed actuation according to the arrangement of magnetic dipoles within the structures, achieving complex twisting and bending deformations. Cylindrical micropillars have been widely used to date, whose circular cross‐sections lead to identical actuation regardless of the actuating direction. In this study, micropillars with triangular or rectangular cross‐sections are designed and fabricated to introduce preferential actuation directions and explore the limits of their actuation. Using such structures, controlled liquid wetting is demonstrated on micropillar surfaces. Liquid droplets pinned on magnetic micropillar arrays undergo directional spreading when the pillars are actuated as depinning of the droplets is enabled only in certain directions. The enhanced deformation due to direction dependent magneto‐mechanical actuation suggests that micropillar arrays can be fundamentally tailored to possess application specific responses and opens up opportunities to exploit more complex designs such as micropillars with polygonal cross sections. Such tunable wetting of liquids on microarray surfaces has potential to improve printing technologies via contactless reconfiguration of stamp geometry by magnetic field manipulation.

Park, Jeong Eun↗
DOE OSTI2020

Particle Response of Antenna-Coupled TES Arrays: Results from SPIDER and the Laboratory

Future mm-wave and sub-mm space missions will employ large arrays of multiplexed transition-edge-sensor (TES) bolometers. Such instruments must contend with the high flux of cosmic rays beyond our atmosphere that induce ‘glitches’ in bolometer data, which posed a challenge to data analysis from the Planck bolometers. Future instruments will face the additional challenges of shared substrate wafers and multiplexed readout wiring. Here, we explore the susceptibility of modern TES arrays to the cosmic ray environment of space using two data sets: the 2015 long-duration balloon flight of the SPIDER cosmic microwave background polarimeter, and a laboratory exposure of SPIDER flight hardware to radioactive sources. We find manageable glitch rates and short glitch durations, leading to minimal effect on SPIDER analysis. We constrain energy propagation within the substrate through a study of multi-detector coincidences and give a preliminary look at pulse shapes in laboratory data.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2022

Design of the SPT-SLIM Focal Plane: A Spectroscopic Imaging Array for the South Pole Telescope

The Summertime Line Intensity Mapper (SLIM) is a mm-wave line-intensity mapping (mm-LIM) experiment for the South Pole Telescope (SPT). The goal of SPT-SLIM is to serve as a technical and scientific pathfinder for the demonstration of the suitability and in-field performance of multi-pixel superconducting filterbank spectrometers for future mm-LIM experiments. Scheduled to deploy in the 2023-24 austral summer, the SPT-SLIM focal plane will include 18 dual-polarisation pixels, each coupled to an $R = \lambda / \Delta \lambda = 300$ thin-film microstrip filterbank spectrometer that spans the 2 mm atmospheric window (120–180 GHz). Each individual spectral channel feeds a microstrip-coupled lumped-element kinetic inductance detector, which provides the highly multiplexed readout for the 10k detectors needed for SPT-SLIM. Here, we present an overview of the preliminary design of key aspects of the SPT-SLIM focal plane array, a description of the detector architecture and predicted performance, and initial test results that will be used to inform the final design of the SPT-SLIM spectrometer array.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

Quantification of the Interaction Field in Arrays of Magnetic Nanowires from the Remanence Curves

A method is presented that allows quantifying the average value of the interaction field in arrays of magnetic nanowires from the field difference between the isothermal remanence (IRM) and the DC demagnetizing (DCD) remanence curves when the normalized magnetization is equal to one third. Arrays of magnetic nanowires of different diameters and packing fractions are used to experimentally test the method. The results have been compared with those obtained using the method based on the difference between the remanence coercivity fields and with a mean-field expression for the interaction field, providing a very good agreement and thus validating the method. Additionally, it is shown that both the position (m{sub 0}) and the shift along the magnetization axis of the intersection between the remanence curves with respect to the value of one third (δm = m{sub 0} − 1/3) provide qualitative information about the interaction field. The former indicates the type of interaction depending if the intersection is above (m{sub 0} > 1/3) or below (m{sub 0} < 1/3), which corresponds to a ferro or anti-ferro magnetic interaction, respectively. While for the latter, it is shown that the maximum deviation of the Delta-M plot from zero (ΔM{sub max}) corresponds to three times the shift (ΔM{sub max} = 3δm).

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Vortex Dynamic Phases in Type II Superconducting Strips with Regular and Flattened Triangular Pinning Arrays

The dynamic behavior of vortices in type II superconducting infinite strips is simulated with two types of triangular pinning lattices: the regular one and a flattened triangular array that mimics the vortex lattice in a superconducting strip in the absence of a pinning array. The calculations were made at zero temperature and perpendicular magnetic field. The size effects are investigated for several strip widths maintaining the density and size of pinning centers unchanged. A driving force is applied in the infinite direction to analyze the depinning process and the different dynamic regimes. For the regular triangular pinning lattice, we found that there is a great richness of vortex dynamical phases because depending on strip width, part of the vortices may stabilize in different interstitial positions and the depinning process depends on the commensurability of each vortex chain. For the flattened triangular lattice, the system exhibits one ordered moving phase for narrower strips and two moving phases for the larger strip. As the transport force increases, vortices in the larger strip go from a disordered to an ordered phase. Moreover, the flattened lattice shows a much higher critical depinning force than the regular one due to commensurability effects.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗