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DOE OSTI2021

Pilot-scale hydrotreating of catalytic fast pyrolysis biocrudes: process performance and product analysis

Catalytic fast pyrolysis (CFP) is a technology option for producing advanced biofuels from hydrocarbon-rich biocrude intermediates. The relatively high oxygen content of biocrudes compared to petroleum intermediates increases hydrogen consumption and the lower thermal stability accelerates catalyst deactivation and reactor fouling hindering the adaptation of hydrotreating technology for biocrude upgrading into biofuels. In this study, four chemically different biocrude feeds were upgraded in a pilot scale hydroprocessing unit at similar process conditions using a commercial hydrodeoxygenation (HDO) catalyst. The biocrude feeds and hydrotreated products were characterized using standard ASTM procedures and advanced analytical techniques (GCxGC-FID and GCxGC-MS). HDO catalyst activity was monitored by changes in physical properties and chemical composition of the upgraded products as a function of time on stream. Aliphatic acids, ketones, aldehydes, and furan derivatives were completely converted during the hydrotreating tests while the concentration of aromatics, aliphatic hydrocarbons and phenolics increased during the hydrotreating tests. The oxygen content, nitrogen content, specific gravity, viscosity and the heavy end of the boiling point range (determined by simulated distillation) of the upgraded products increased with increasing time on stream during hydrotreating. The deactivation rate was the lowest for the biocrude feed that contained the most aliphatic and aromatic hydrocarbons and was the highest for the biocrude feed that had the most anhydrosugars. Overall, the HDO deactivation rate correlates with the total amount of oxygen in the feed (17 wt% to 29 wt%, on a wet basis).

09 BIOMASS FUELS↗

DOE OSTI2026

NiFeCo-based catalysts in high current zero-gap anion exchange membrane water electrolyzers

Understanding degradation mechanisms in pure water anion exchange membrane water electrolyzers is essential for developing durable and precious metal-free hydrogen production systems, yet electronic, chemical, and transport-driven pathways often occur simultaneously at the anode. To separate these effects, we establish a morphology invariant Ni/Fe/Co thin film model catalyst platform using physical vapor deposition and systematically compare composition-dependent behavior under both pure water and 0.1 M KOH feeds. Devices were operated under industrially relevant current density conditions, galvanostatically at 1 A cm −2 for 24 hours; metal dissolution, ionomer oxidation, and resistance growth were quantified using inductively coupled plasma mass spectrometry, X-ray photoelectron spectroscopy (XPS), and electrochemical impedance spectroscopy. Under pure-water operation, Ni-rich films showed voltage increases that correlated with rising total cell resistance (ΔV ≈ 243 mV, ΔR ≈ 0.17 Ω cm 2 ). Co-rich films maintained near constant voltages with minimal resistance change (ΔV < 10 mV, ΔR ≈ 0.03 Ω cm 2 ) but induced pronounced ionomer oxidation observed by XPS. In 0.1 M KOH, ionomer oxidation is suppressed, and impedance growth is minimized (<0.08 Ω cm 2 ) across all compositions, consistent with reduced transport limitations and improved ionic conduction relative to pure-water feeds. These results demonstrate how a controlled thin film model platform can isolate composition electrolyte relationships and provide mechanistic design principles for stable pure water anion exchange membrane electrolyzers.

Milenia Rojas Mendoza, B. [Stanford Univ., CA (Uni↗

DOE OSTI2023

Pressure-driven tearing and thermal transport in finite-beta reversed field pinch computations

In this work, nonlinear resistive-magnetohydrodynamics (MHD) computation with heating and anisotropic transport is applied to examine the interaction between thermal energy and magnetic fluctuations in inductively driven reversed-field pinches (RFPs). The magnetic fluctuations underlie magnetic field reversal through dynamo-like correlations, and they enhance thermal energy transport through fluctuations of parallel heat flux density. With the unfavorable magnetic curvature that exists across the RFP profile, thermal energy also affects the magnetic fluctuations. Computations with the NIMROD code [Sovinec et al., J. Comput. Phys. 195, 355–386 (2004)] integrate nonlinear MHD dynamics with energy transport and reproduce an RFP state with experimentally relevant values of plasma-β. Equilibria constructed from results of the 3D computations are analyzed to assess the sources of free energy in the saturated nonlinear state. Linear computations for these profiles show unstable modes of tearing parity. Their eigenfunctions are used to evaluate and compare stabilizing and destabilizing contributions to the kinetic energy integral. An assessment of the drives in the integral reveals that the pressure gradient drive is of comparable magnitude to the parallel current drive, and only the sum of the two surpasses the stabilizing contributions. Correlation of magnetic and parallel heat flux density fluctuations in the nonlinear computations shows that fluctuation-induced thermal conduction is the dominant mode of energy loss, as expected from experimental evidence. Decomposition of the fluctuating heat flux density shows that second-order correlations, alone, do not explain the total energy transport. Higher-order correlations are also important.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2026

Dynamics of iodine geminate recombination in supercritical xenon solvent: Caging effect

Understanding the dynamics of chemical reactions in solutions is vital, as their rates and kinetics are significantly affected by the solvent environment. Supercritical solvents offer extensive applications in chemical reactions by enabling the manipulation of the solution environment. Here, in this study, we investigate the geminate recombination of iodine in a supercritical xenon solvent by using ReaxFF-based molecular dynamics simulations. Our findings reveal that the highest iodine recombination rate occurs near supercritical conditions, while lower-pressure conditions lead to reduced collision rates and unstable recombination, and higher-pressure conditions hinder iodine diffusion, resulting in a lower recombination rate. Our analysis shows that the xenon local density at the time of recombination is at least 2.5 times higher than the global density, confirming the presence of xenon clusters surrounding the Iodine atoms. This observation is further supported by coordination number analysis, which confirms an elevated xenon local density during recombination. In addition, the correlation between the total energy of xenon atoms within a cluster and recombined iodine atoms underscores the kinetic energy transfer process, validating the occurrence of geminate recombination. The excess kinetic energy from the recombining iodine atoms is transferred to the surrounding xenon atoms. Our examination of geminate recombination demonstrates that iodine atoms confined within xenon clusters—whether through manual insertion of atoms or the fast dissociation of an iodine molecule within xenon clusters—are more likely to recombine as primary geminate recombination. However, extending the iodine molecule dissociation time allows iodine atoms to diffuse out of the cluster, and the recombination to shift toward secondary geminate recombination.

Cage effect↗

DOE OSTI2023

Correlations between energy and $\gamma$-ray emission in 239 Pu($n, f$)

Here, we study $\gamma$-ray emission following $^{239}\mathrm{Pu}(n,\mathrm{f})$ over an incident neutron energy range of $2 < E_i < 40$ MeV. We present the first experimental evidence for positive correlations between the total angular momentum generated in fission and the excitation energy of the compound nucleus prior to fission. The $\gamma$-ray multiplicity increases linearly with incident energy below the 2\textsuperscript{nd}-chance fission threshold with a slope of $0.085 \pm 0.010$~MeV$^{-1}$. This linear trend appears to hold for the average excitation energy of the compound nucleus between $9 < \langle E_x \rangle < 19$ MeV. Most of the multiplicity increase comes from an enhancement around a $\gamma$-ray energy of 0.7 MeV, which we interpret as stretched quadrupole $\gamma$ rays that indicate an increase in total fission-fragment angular momentum with excitation energy.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2018

Hauser-Feshbach fission fragment de-excitation with calculated macroscopic-microscopic mass yields

The Hauser-Feshbach statistical model is applied to the de-excitation of primary fission fragments using input mass yields calculated with macroscopic-microscopic models of the potential energy surface. We test the sensitivity of the prompt fission observables to the input mass yields for two important reactions, 235 U (n th , f) and 239 Pu (n th , f) , for which good experimental data exist. General traits of the mass yields, such as the location of the peaks and their widths, can impact both the prompt neutron and γ-ray multiplicities, as well as their spectra. Specifically, we use several mass yields to determine a linear correlation between the calculated prompt neutron multiplicity $\bar{v}$ and the average heavy-fragment mass $\langle$A h $\rangle$ of the input mass yields ∂$\bar{v}$/∂ $\langle$A h $\rangle$ = ± 0.1 (n / f )/u . The mass peak width influences the correlation between the total kinetic energy of the fission fragments and the total number of prompt neutrons emitted, $\bar{v}_T$ ( TKE ) . Finally, typical biases on prompt particle observables from using calculated mass yields instead of experimental ones are δ$\bar{v}$ = 4 % for the average prompt neutron multiplicity, δ$\overline{M}_γ$ = 1% for the average prompt γ-ray multiplicity, δ$\bar{ε}$ $LAB\atop{n}$ = 1 % for the average outgoing neutron energy, δ$\bar{ε}_γ$ = 1 % for the average γ-ray energy, and δ $\langle$TKE$\rangle$ = 0.4 % for the average total kinetic energy of the fission fragments.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2022

Association of Diet and Antimicrobial Resistance in Healthy U.S. Adults

Antimicrobial resistance (AMR) represents a significant source of morbidity and mortality worldwide, with expectations that AMR-associated consequences will continue to worsen throughout the coming decades. Since resistance to antibiotics is encoded in the microbiome, interventions aimed at altering the taxonomic composition of the gut might allow us to prophylactically engineer microbiomes that harbor fewer antibiotic resistant genes (ARGs). Diet is one method of intervention, and yet little is known about the association between diet and antimicrobial resistance. To address this knowledge gap, we examined diet using the food frequency questionnaire (FFQ; habitual diet) and 24-h dietary recalls (Automated Self-Administered 24-h [ASA24 ® ] tool) coupled with an analysis of the microbiome using shotgun metagenome sequencing in 290 healthy adult participants of the United States Department of Agriculture (USDA) Nutritional Phenotyping Study. We found that aminoglycosides were the most abundant and prevalent mechanism of AMR in these healthy adults and that aminoglycoside-O-phosphotransferases (aph3-dprime) correlated negatively with total calories and soluble fiber intake. Individuals in the lowest quartile of ARGs (low-ARG) consumed significantly more fiber in their diets than medium- and high-ARG individuals, which was concomitant with increased abundances of obligate anaerobes, especially from the family Clostridiaceae, in their gut microbiota. Finally, we applied machine learning to examine 387 dietary, physiological, and lifestyle features for associations with antimicrobial resistance, finding that increased phylogenetic diversity of diet was associated with low-ARG individuals. These data suggest diet may be a potential method for reducing the burden of AMR.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2022

Effect of Annealing Conditions on Recovery of Lattice Damage in a High-Energy-Implanted 4H-SiC Superjunction PIN Diode

A high energy ion implantation system has been recently developed at the Tandem Van de Graaff facility at Brookhaven National Laboratory with tunable energy to 150 MeV capable of multi-step, deep implantation in 4H-SiC wafers with dopant atoms, such as B, P, Al, and N. Medium and high voltage devices with deep junctions can be fabricated using this system. Lattice strain introduced by the implantation process needs to be recovered and dopant atoms activated by appropriate annealing process as the device performance is strongly associated with the extent of recovery of the lattice. Using Synchrotron X-ray Rocking Curve Topography (SXRCT) and Reciprocal Space Mapping (RSM), the strain induced by high energy implantation of Al and N in 4H-SiC in different patterns are measured and mapped. It is observed that the strain levels correlate with the total fluence levels. PiN diodes fabricated on these implanted wafers were then annealed at temperatures ranging from 1700 °C to 2000 °C for 60 min. The SXRCT and RSM analysis of the annealed samples suggests that for the same annealing duration, higher temperature leads to better lattice recovery.

43 PARTICLE ACCELERATORS↗

DOE OSTI2024

Quantitative phenotyping of crop roots with spectral electrical impedance tomography: a rhizotron study with optimized measurement design

Background: Root systems are key contributors to plant health, resilience, and, ultimately, yield of agricultural crops. To optimize plant performance, phenotyping trials are conducted to breed plants with diverse root traits. However, traditional analysis methods are often labour-intensive and invasive to the root system, therefore limiting high-throughput phenotyping. Spectral electrical impedance tomography (sEIT) could help as a non-invasive and cost-efficient alternative to optical root analysis, potentially providing 2D or 3D spatio-temporal information on root development and activity. Although impedance measurements have been shown to be sensitive to root biomass, nutrient status, and diurnal activity, only few attempts have been made to employ tomographic algorithms to recover spatially resolved information on root systems. In this study, we aim to establish relationships between tomographic electrical polarization signatures and root traits of different fine root systems (maize, pinto bean, black bean, and soy bean) under hydroponic conditions. Results: Our results show that, with the use of an optimized data acquisition scheme, sEIT is capable of providing spatially resolved information on root biomass and root surface area for all investigated root systems. We found strong correlations between the total polarization strength and the root biomass (R 2 = 0.82) and root surface area (R 2 = 0.8). Our findings suggest that the captured polarization signature is dominated by cell-scale polarization processes. Additionally, we demonstrate that the resolution characteristics of the measurement scheme can have a significant impact on the tomographic reconstruction of root traits. Conclusion: Our findings showcase that sEIT is a promising tool for the tomographic reconstruction of root traits in high-throughput root phenotyping trials and should be evaluated as a substitute for traditional, often time-consuming, root characterization methods.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2022

Elevations in Tumor Necrosis Factor Alpha and Interleukin 6 From Neuronal-Derived Extracellular Vesicles in Repeated Low-Level Blast Exposed Personnel

The purpose of this pilot study was to determine if military service members with histories of hundreds to thousands of low-level blast exposures (i. e., experienced breachers) had different levels of serum and neuronal-derived extracellular vesicle (EV) concentrations of interleukin (IL)-6, IL-10, and tumor necrosis factor alpha (TNFα), compared to matched controls, and if these biomarkers related to neurobehavioral symptoms. Participants were experienced breachers (n = 20) and matched controls without blast exposures (n = 14). Neuronal-derived EVs were isolated from serum and identified with mouse anti-human CD171. Serum and neuronal-derived EVs were analyzed for IL-6, IL-10, and TNFα using an ultra-sensitive assay. Serum TNFα concentrations were decreased in breachers when compared to control concentrations (p < 0.01). There were no differences in serum concentrations of IL-6, IL-10, or the IL-6/IL-10 ratio between breachers and controls (p's > 0.01). In neuronal-derived EVs, TNFα and IL-6 levels were increased in breachers compared to controls (p's < 0.01), and IL-10 levels were decreased in the breacher group compared to controls (p < 0.01). In breachers the IL-6/IL-10 ratio in neuronal-derived EVs was higher compared to controls, which correlated with higher total Rivermead Post-concussion Questionnaire (RPQ) scores (p's < 0.05). These findings suggest that exposure of personnel to high numbers of low-level blast over a career may result in enduring central inflammation that is associated with chronic neurological symptoms. The data also suggest that peripheral markers of inflammation are not necessarily adequate surrogates for central neuroinflammation.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2022

Influence of Superlattice Structure on V-Defect Distribution, External Quantum Efficiency and Electroluminescence for Red InGaN Based µLEDs on Silicon

Achieving high quantum efficiency in long-wavelength LEDs has posed a significant challenge to the solid-state lighting and display industries. In this article, we use V-defect engineering as a technique to achieve higher efficiencies in red InGaN LEDs on (111) Si through lateral injection. We investigate the effects of superlattice structure on the V-defect distribution, the electroluminescence properties, and the external quantum efficiency. Increasing the relative thickness of In in the InGaN/GaN superlattice and the total superlattice thickness correlate with a reduction of active region defects and increased external quantum efficiencies. The highest measured on-chip EQE was 0.15% and based on Monte-Carlo ray tracing simulations for light extraction we project this would correspond to a flip-chip EQE of ~2.5%.

36 MATERIALS SCIENCE↗

DOE OSTI2021

Efficacy of a portable, moderate-resolution, fast-scanning differential mobility analyzer for ambient aerosol size distribution measurements

Abstract. Ambient aerosol size distributions obtained with a compact scanning mobility analyzer, the “Spider” differential mobility analyzer (DMA), are compared to those obtained with a conventional mobility analyzer, with specific attention to the effect of mobility resolution on the measured size distribution parameters. The Spider is a 12 cm diameter radial differential mobility analyzer that spans the 10–500 nm size range with 30 s mobility scans. It achieves its compact size by operating at a nominal mobility resolution R=3 (sheath flow = 0.9 L min−1; aerosol flow = 0.3 L min−1) in place of the higher ratio of sheath flow to aerosol flow commonly used. The question addressed here is whether the lower resolution is sufficient to capture key characteristics of ambient aerosol size distributions. The Spider, operated at R=3 with 30 s up- and downscans, was co-located with a TSI 3081 long-column mobility analyzer, operated at R=10 with a 360 s sampling duty cycle. Ambient aerosol data were collected over 26 consecutive days of continuous operation, in Pasadena, CA. Over the 17–500 nm size range, the two instruments exhibit excellent correlation in the total particle number concentrations and geometric mean diameters, with regression slopes of 1.13 and 1.00, respectively. Our results suggest that particle sizing at a lower resolution than typically employed may be sufficient to obtain key properties of ambient size distributions, at least for these two moments of the size distribution. Moreover, it enables better counting statistics, as the wider transfer function for a given aerosol flow rate results in a higher counting rate.

54 ENVIRONMENTAL SCIENCES↗

NASA NTRS1972

Study of carbon compounds in Apollo 12 and 14 lunar samples.

The results of gas-chromatography and high-resolution mass spectroscopy studies of gases released on deuterium fluoride dissolution of Apollo 12 and 14 lunar samples are reported. The results confirm previous observations that CH4 and C2H6 are released as well as CD4, C2D4, C2D6, and higher deuterated hydrocarbons. The yields correlate with the total carbon content of the samples, and the CH4 and C2H6 released may be regarded as indigenous, while the deuterated products result from hydrolysis of carbide material. The results provide the first experimental confirmation of the hypothesis that the CH4 derives from solar wind interactions.

Holland, P. T.↗

NASA NTRS1977

Applications of infrared band model correlations to nongray radiation

Various correlations for the total absorptance of a wide band are presented. These are employed in two physically realistic problems (radiative transfer in gases with internal heat source and heat transfer in laminar flow of absorbing-emitting gasses between parallel plates) to study their influence on final radiative transfer results.

Tiwari, S. N.↗

NASA NTRS1983

Mechanism and kinetics of the curing process in a resin system

The present investigation is concerned with the development of a cure reactivity model for a resin system consisting of tetraglycidyl diaminodiphenyl methane (TGDDM) and diaminodiphenyl sulfone (DDS), taking into account the temperature range from 153 to 177 C. Differential scanning calorimetry and FT-IR spectroscopy have been used to investigate the cure kinetics of the resin with the objective to obtain a correlation between the total conversion and the rates of formation and disappearance of specific functionalities. It was found that the overall process can be satisfactorily described in terms of two first order processes.

Moacanin, J.↗

NASA NTRS1984

Cyclic debonding of adhesively bonded composites

To analyze the fatigue behavior of a simple composite-to-composite bonded joint, a combined experimental and analytical study of the cracked-lap-shear specimen subjected to constant-amplitude cyclic loading was undertaken. Two bonded systems were studied: T300/5208 graphite/epoxy adherends bonded with adhesives EC 3445 and with FM-300. For each bonded system, two specimen geometries were tested: (1) a strap adherend of 16 plies bonded to a lap adherend of 8 plies, and (2) a strap adherend of 8 plies bonded to a lap adherend of 16 plies. In all specimens tested, the fatigue failure was in the form of cyclic debonding with some 0 deg fiber pull-off from the strap adherend. The debond always grew in the region of adhesive that had the highest mode I (peel) loading and that region was close to the adhesive-strap interface. Furthermore, the measured cyclic debond growth rates correlated well with total strain energy release rates G(T) as well as with its components G(I) (peel) and G(II) (shear) for the mixed-mode loading in the present study.

Mall, S.↗

NASA NTRS1986

The impact of physical and mental tasks on pilot mental workoad

Seven instrument-rated pilots with a wide range of backgrounds and experience levels flew four different scenarios on a fixed-base simulator. The Baseline scenario was the simplest of the four and had few mental and physical tasks. An activity scenario had many physical but few mental tasks. The Planning scenario had few physical and many mental taks. A Combined scenario had high mental and physical task loads. The magnitude of each pilot's altitude and airspeed deviations was measured, subjective workload ratings were recorded, and the degree of pilot compliance with assigned memory/planning tasks was noted. Mental and physical performance was a strong function of the manual activity level, but not influenced by the mental task load. High manual task loads resulted in a large percentage of mental errors even under low mental task loads. Although all the pilots gave similar subjective ratings when the manual task load was high, subjective ratings showed greater individual differences with high mental task loads. Altitude or airspeed deviations and subjective ratings were most correlated when the total task load was very high. Although airspeed deviations, altitude deviations, and subjective workload ratings were similar for both low experience and high experience pilots, at very high total task loads, mental performance was much lower for the low experience pilots.

Berg, S. L.↗

NASA NTRS1986

HCN production from Comet Halley

Observations of the HCN J=1-0 rotational transition at 3.4 mm wavelength in comet P/Halley with a 14m antenna were obtained during 56 individual observing sessions between Nov. 1985 and May 1986. The HCN production rate is well correlated with the total visual magnitude of the comet, indicating that HCN follows the overall gas and dust production. However, comparison of HCN production to the total gas production of the comet indicates that it is a relatively minor consitiuent with 0.1% of the abundance of H2O. Spectra obtained by binning the HCN data with heliocentric distance show that the HCN line width, and thus the parent outflow velocity, increases with decreasing heliocentric distance, and that there is a tendency for the lines to be blue shifted as expected from the observed anisotropic outgassing from the nucleus. There is evidence of day-to-day time variability in the total HCN emission and variations in the HCN hyperfine ratios from their LTE values.

Schloerb, F. Peter↗