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At least 937 records · Page 52

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DOE OSTI2026

Reaction Optimization for Enzymatic Deconstruction of Industrially Relevant Nylon Composites

Plastics such as polyamides (PAs) possess unique physicochemical properties that make them indispensable in modern society. However, their energy‐intensive production and challenging end‐of‐life management highlight the urgent need for efficient recycling or remanufacturing solutions. Enzymatic depolymerization offers a promising route toward circular recycling, yet remains constrained by limited enzyme characterization, lack of validation under industrially relevant conditions and substrates, and overall performance. Here, we optimized the reaction conditions for three recently discovered nylon‐degrading enzymes. One of them, Nyl12, achieved product titers with PA6 and PA66 that exceed previously reported values, without enzyme engineering or substrate pretreatment. We further demonstrated the scalability of the process and its application to complex PA‐based materials used in microelectronic components. Analysis of substrate features, including surface area and particle size, revealed key parameters governing enzymatic activity and provided a framework for future pretreatment and process optimization efforts. In combination, these efforts provide a new benchmark for enzymatic nylon recycling.

nylon↗

DOE OSTI2026

Sculpting 2D Crystals via Membrane Contractions before and during Solidification

When phospholipids crystallize within the otherwise fluid membranes of giant unilamellar vesicles, the resulting molecularly thin “2D” solids exhibit great variety in their morphology evolution. For example, within membranes containing moderate amounts of the crystallizing component, crystals grow with a fixed morphology depending on vesicle size. Conversely for membranes containing large amounts of the crystallizing species, we find small compact crystals on vesicles of all sizes. However, on large vesicles, growing crystals sprout flower petals that lengthen progressively. These behaviors result from two combined mechanisms: first, like other 2D solids, the shear rigidity of phospholipid crystals renders them intolerant to morphologies with nonzero Gaussian curvature. As a result and especially at elevated membrane tension, the cost of bending elasticity is reduced at the expense of line energy by the formation of flowers as opposed to compact crystals. Second, the composition-dependent tension rise during cooling relaxes via water permeation of the membrane with a time constant scaling as R2. The amount of crystal formed for a small decrease in temperature determines this composition-dependent increase in stress from thermal contractions versus solidification. Surface Evolver computations were motivated using the predicted tension evolution to develop a processing space that maps to experimental observations for initial and growing crystal morphology. Important variable groups are identified, including a scaled ratio of bending to line energy, a vesicle-size-independent group for membrane contractions, and a time constant for stress relaxation. Though processing stresses ultimately relax, the crystal morphology persists well beyond the processing window.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2020

Specific features of fluorescence transfer in multiply scattering randomly inhomogeneous layers under intense laser pumping

Based on the analysis of experimental data on the effect of the pulsed laser pump intensity on the spectral properties and the size of the fluorescent response zone in randomly inhomogeneous fluorescent layers, we found that the amplification of spontaneous and stimulated emission significantly affects the statistical properties of the propagation lengths of the fluorescent field partial components in the layers. The experiments are performed with layers of SiO{sub 2} and TiO{sub 2} nanoparticles saturated with rhodamine 6G, pumped by 532-nm laser radiation in the intensity range corresponding to the transient regime from excitation of spontaneous fluorescence to random lasing in the layer. The experimental data are compared with the results of statistical modelling of fluorescence transfer. It is shown that, even at a pump intensity below the random lasing threshold, the spontaneous emission amplification in a layer leads to a significant increase in the contributions to the fluorescence response from partial components with propagation lengths much larger than the layer thickness. This can be interpreted as a manifestation of the quasi-waveguide effect, in which the probability of propagation of diffuse fluorescence components along the layer over distances many times greater than its thickness and the size of the pumped region increases significantly with a decrease in the characteristic radiation amplification length in the layer. (paper)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2023

Final Design of Vacuum Pumping Systems for the Material Plasma Exposure eXperiment

The Material Plasma Exposure eXperiment (MPEX) vacuum pumping system is responsible for creating prototypic conditions in the plasma material interaction chamber that mimic those in a fusion reactor divertor region. Additionally, the vacuum system needs to minimize the pressure in the plasma heating region to improve the coupling of the electron cyclotron heating and ion cyclotron heating to the plasma, minimizing waste heat exhausted to high heat flux components. Here, the final design of the system has been sized to comply with the vacuum pump operating environment and to reduce the number of unique pumps required while meeting performance requirements. Bounding cases with and without the plasma present have been developed in the pumping analysis, and an initial calculation has been performed based on the plasma pumping identified in Proto-MPEX operation though this result will remain unverified until MPEX operation.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2021

Hypothesis tests on Rayleigh wave radiation pattern shapes: a theoretical assessment of idealized source screening

SUMMARY Shallow seismic sources excite Rayleigh wave ground motion with azimuthally dependent radiation patterns. We place binary hypothesis tests on theoretical models of such radiation patterns to screen cylindrically symmetric sources (like explosions) from non-symmetric sources (like non-vertical dip-slip or non-VDS faults). These models for data include sources with several unknown parameters, contaminated by Gaussian noise and embedded in a layered half-space. The generalized maximum likelihood ratio tests that we derive from these data models produce screening statistics and decision rules that depend on measured, noisy ground motion at discrete sensor locations. We explicitly quantify how the screening power of these statistics increase with the size of any dip-slip and strike-slip components of the source, relative to noise (faulting signal strength) and how they vary with network geometry. As applications of our theory, we apply these tests to (1) find optimal sensor locations that maximize the probability of screening non-circular radiation patterns and (2) invert for the largest non-VDS faulting signal that could be mistakenly attributed to an explosion with damage, at a particular attribution probability. Finally, we quantify how certain errors that are sourced by opening cracks increase screening rate errors. While such theoretical solutions are ideal and require future validation, they remain important in underground explosion monitoring scenarios because they provide fundamental physical limits on the discrimination power of tests that screen explosive from non-VDS faulting sources.

58 GEOSCIENCES↗

DOE OSTI2021

Electric-field enhancement caused by subwavelength-sized particles located on the surface of multilayer dielectric mirrors

A laser pulse impinging on the surface of an optical component can interact with particles, such as contamination debris, to produce a scattered electric field, which, either by itself or combined with the incident laser field, coherently can significantly increase the local field intensity. This effect can be of critical importance as it can reduce the laser-induced–damage threshold of the affected component. In this work, we use a field-propagation code to improve understanding regarding the factors that determine the magnitude and location of the electric-field enhancement for the case of subwavelength-sized particles located on the surface of multilayer dielectric mirrors.

47 OTHER INSTRUMENTATION↗

NASA NTRS1969

Substitution of stable isotopes in Chlorella

Replacement of biologically important isotopes in the alga Chlorella by corresponding heavier stable isotopes produces increasingly greater deviations from the normal cell size and changes the quality and distribution of certain cellular components. The usefulness of isotopically altered organisms increases interest in the study of such permuted organisms.

Flaumenhaft, E.↗

NASA NTRS1971

Design features and results from fatigue reliability research machines.

The design, fabrication, development, operation, calibration and results from reversed bending combined with steady torque fatigue research machines are presented. Fifteen-centimeter long, notched, SAE 4340 steel specimens are subjected to various combinations of these stresses and cycled to failure. Failure occurs when the crack in the notch passes through the specimen automatically shutting down the test machine. These cycles-to-failure data are statistically analyzed to develop a probabilistic S-N diagram. These diagrams have many uses; a rotating component design example given in the literature shows that minimum size and weight for a specified number of cycles and reliability can be calculated using these diagrams.

Lalli, V. R.↗

NASA NTRS1974

Interpretation of epsilon Aurigae. II - Infrared excess, secondary light variations, and plausible formation of a planetary system

Infrared excess based on the disk model proposed in a previous paper was computed. It was found that the disk alone will emit infrared radiation below the margin of detection. However, if individual condensations are present, the combined result of the disk proper and the condensations yields results of infrared excesses that are consistent with observations. The presence of condensations also makes the secondary light variation understandable. An elementary theory is developed that analyzes such light variations. The result of the analysis yields the size of the orbit of the condensation around the secondary component.

Huang, S.-S.↗

NASA NTRS1976

Digital video image system

Interactive recording and display device acts as very-high-speed data-input/output interface between analog (video) signals and standard digital-computer components. System can be used with various picture and memory sizes and can be controlled manually or by computer.

Neely, P. L.↗

NASA NTRS1982

Lunar regolith - Petrology of the less than 10 micron fraction

Petrographic data for the less than 10 micron fraction from four lunar surface soils are presented in an attempt to characterize the modal mineralogy of this fraction. Individual grains were studied with a scanning/transmission electron microscope with an attached energy dispersive spectrometer. Energy dispersive analytical data are presented, and comparative modal petrology of the soils is shown. Also presented are grain size histograms and diagrammatic representation of comparative modal data for the soils, as well as the feldspathic glass/mafic glass ratio, plagioclase/mafic mineral ratio, and SiO2 modal percent for different size fractions of the four types of soil. The modal results are consistent with chemical data regarding feldspathic and KREEP enrichment in the finest fraction. Grain-size distributions are inconsistent with a fine-grained exotic component derived from distant sources.

Devine, J. M.↗

NASA NTRS1983

Large space structures raise testing challenges

The testing approaches and techniques necessary for combined ground and space verification for large space structures (LSS) to be deployed and assembled in space are explored. The size of LSS precludes full ground tests, thereby requiring assemblies, components, and their interactions to be examined on orbit. Ground tests involving drop tests and zero-g aircraft flights can be performed with scale models, but need computational compensation to eliminate gravitational and torque effects that do not occur in space. Structural rigidity also varies from ground to space, and can partly be accounted for in ground tests by using cable supports, although numerical modelling must remove the effects of the cables' presence. Long-term funding is recommended for on-orbit tests of components in order to build a data base for later testing and actual construction of LSS.

Hanks, B. R.↗

NASA NTRS1983

Models of the hard X-ray spectrum of AM Herculis and implications for the accretion rate

Phenomenological fits to the hard X-ray spectrum of AM Herculis left unexplained the high equivalent width (0.8 + or - 0.1 keV) of Fe K alpha emission. A purely thermal origin implies a much steeper spectrum than was observed. With Monte Carlo calculations, scattering and fluorescent line production in a cold or partially ionized accretion column of hard X-rays emitted at the base were investigated. The strength of the iron emission and the flat spectral continuum can be explained by the effects of fluorescence and absorption within the accretion column and the surface of the white dwarf on a thermal X-ray spectrum. Thomson optical depths across the column in the range 0.2 to 0.7 are acceptable. The accretion rate and gravitational power can be deduced from the optical depth across the column, if the column size is known, and, together with the observed hard X-ray and polarized light luminosities, imply a lower limit for the luminosity in the UV to soft X-ray range, for which the observations give model-dependent values. Estimates of the column size differ by a factor of 40. Small spot sizes and low luminosities would be consistent with the soft component being the expected reprocessed bremsstrahlung and cyclotron radiation, although the constraint of matching the spectrum confines one to solutions with fluxes exceeding 20% the Eddington limits.

Swank, J. H.↗

NASA NTRS1984

Very Long Baseline Interferometry observations of 257 extragalactic radio sources in the ecliptic region

Very Long Baseline Interferometry observations of 257 extragalactic radio sources with 10 deg of the ecliptic have been conducted at a frequency of 2.29 GHz. Compact components with flux densities greater than 0.1 Jy and angular sizes smaller than the fringe spacings of 2.5 and 3.2 milliarsec were detected in 144 radio sources. This survey was conducted to find compact radio sources to form a high accuracy reference frame for planetary spacecraft navigation. This stable reference frame may also be useful for long-term studies of planetary dynamics.

Wehrle, A. E.↗

NASA NTRS1985

Regenerative fuel cell systems for space station

Regenerative fuel cell (RFC) systems are the leading energy storage candidates for Space Station. Key design features are the advanced state of technology readiness and high degree of system level design flexibility. Technology readiness was demonstrated through testing at the single cell, cell stack, mechanical ancillary component, subsystem, and breadboard levels. Design flexibility characteristics include independent sizing of power and energy storage portions of the system, integration of common reactants with other space station systems, and a wide range of various maintenance approaches. The design features led to selection of a RFC system as the sole electrochemical energy storage technology option for the space station advanced development program.

Hoberecht, M. A.↗

NASA NTRS1987

New dimension analyses with error analysis for quaking aspen and black spruce

Dimension analysis for black spruce in wetland stands and trembling aspen are reported, including new approaches in error analysis. Biomass estimates for sacrificed trees have standard errors of 1 to 3%; standard errors for leaf areas are 10 to 20%. Bole biomass estimation accounts for most of the error for biomass, while estimation of branch characteristics and area/weight ratios accounts for the leaf area error. Error analysis provides insight for cost effective design of future analyses. Predictive equations for biomass and leaf area, with empirically derived estimators of prediction error, are given. Systematic prediction errors for small aspen trees and for leaf area of spruce from different site-types suggest a need for different predictive models within species. Predictive equations are compared with published equations; significant differences may be due to species responses to regional or site differences. Proportional contributions of component biomass in aspen change in ways related to tree size and stand development. Spruce maintains comparatively constant proportions with size, but shows changes corresponding to site. This suggests greater morphological plasticity of aspen and significance for spruce of nutrient conditions.

Woods, K. D.↗

NASA NTRS1986

EZ Pegasi - The last pieces of the puzzle

Based on UBV differential photometric observations carried out at the Braeside Observatory between October 19, 1984 and January 11, 1985, it is shown that EZ Peg is in synchronous rotation with a photometric period of 11.6626 days. The orbital solution of Griffin (1985) is in good agreement with the present results, and it is employed to analyze the emission properties of the Ca II and H-alpha emission in the system. It is suggested that the emission of the system is almost entirely associated with the primary component, and the two stars appear to be similar in size and luminosity.

Howell, S. B.↗

NASA NTRS1987

An experimental study on the effects of tip clearance on flow field and losses in an axial flow compressor rotor

Detailed measurement of the flow field in the tip region of a compressor rotor was carried out using a Laser Doppler Velocimeter (LDV) and a Kiel probe at two different tip clearance heights. At both clearance sizes, the relative stagnation pressure and the axial and tangential components of relative velocities were measured upstream, inside the passage and downstream of the rotor, up to about 20 percent of the blade span from the annulus wall. The velocities, outlet angles, losses, momentum thickness, and force defect thickness are compared for the two clearances. A detailed interpretation of the effect of tip clearance on the flow field is given. There are substantial differences in flow field, on momentum thickness, and performance as the clearance is varied. The losses increase linearly within the passage and their values increase in direct proportion to tip clearance height. No discernable vortex (discrete) is observed downstream of the rotor.

Lakshminarayana, B.↗