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At least 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Reactor Network Analysis with Various Reaction Mechanisms to Investigate Hydrogen vs. Methane Fuel at Varying Flame Temperatures with Experimental Data

Emissions data were evaluated for a set of test hardware that adapts Collins Aerospace’s aeroengine liquid fueled injector technology to a ground-based turbine. The hardware was specifically developed to operate on 100% hydrogen; however it has the ability to operate on both pure methane and hydrogen and mixtures in between. 16 injector configurations and seven factors (air split, fuel and air swirl, pressure drop, preheat temperature, fuel composition, and flame temperature) were investigated based on a Box Behnken statistical model. Of the 16, configuration 3 was selected for further discussion being in the middle of the statistical design space. A chemical reactor network was developed based on the experimental data obtained and was assessed with three different mechanisms: GRI Mech 3.0, UCSD, and Galway. All factors were held constant except the fuel composition to directly compare chemical pathways for methane and hydrogen. This study was conducted across different flame temperatures of 1500K, 1675K, and 1850K for both hydrogen and methane. Additional lower flame temperatures of 1100K and 1300K were evaluated for hydrogen. Moreover, results for fully premixed and non-premixed results were compared to obtain information on the implications of mixedness on emissions. These results were compared with the Leonard and Stegmaier plot for methane and a similar plot was constructed for hydrogen.

08 HYDROGEN↗
DOE OSTI2024

The 2022 Russian Invasion of Ukraine: Nuclear Supply Chains vs. Sanctions

The United States and European countries are unlikely to collectively approve of sanctions against Russian exports of nuclear fuel assemblies and uranium in the near term despite the 2022 invasion of Ukraine. Rather than bearing the costs that cutting off Russian imports would have on domestic nuclear energy production, the United States and European countries are more likely to prefer developing alternative supply chains of nuclear fuel and enriched uranium to reduce dependence on Russian resources. This outlook is primarily based on two areas of evaluation: (1) comparison of the Russian-made reactor fuel supply chain within the European Union (EU) in 2014 following the annexation of Crimea and in 2022 following the invasion of Ukraine, and (2) the dependence of France and the United States on Russia’s exports of enriched uranium. Additionally, the potential impacts to Kazakh uranium exports if trade routes for nuclear resources through Russia became unavailable were considered as an additional factor in the push for disentanglement from Russian nuclear resources. This work utilized BACI, a database of harmonized international trade data at the product level drawn from the United Nations Comtrade Database and created by the French international economics research institute CEPII.1 Comparisons of imports and exports were based on the trade value in U.S. dollars as reported in BACI instead of the quantity of the traded product. This evaluation only considers import and export data up until 2021, since the trade data for 2022 is incomplete within the Comtrade Database for several of the key countries presented in this work, including Australia, Canada, Namibia, Niger, and Russia.

Political science↗
DOE OSTI2025

IT vs. OT: Trends and Incidents

This presentation discusses the differences between information systems (IT) and operational systems (OT) and why that difference is important in the context of cybersecurity for the energy sector.

29 - ENERGY PLANNING, POLICY AND ECONOMY↗
DOE OSTI2025

Nitrate-To-Ammonia Electroconversion at Neutral pH on Polycrystalline Vanadium Sulfide Derived from Vanadium Disulfide

The electrochemical nitrate reduction reaction (NO3RR) offers a pathway to produce NH3 for fuel and fertilizer from waste NO3-. In this work, a polycrystalline vanadium sulfide (VSx), which is derived from solvothermally grown and annealed VS2, is shown to exhibit excellent NO3RR activity (2.3 +- 0.6 mg.cm-2 geo..h-1 @ -0.92 VRHE) and Faradaic efficiency to NH4+ (69 +- 6% at -0.69 VRHE) in buffered neutral pH electrolyte containing 0.1 M NO3-. A variety of characterization techniques are leveraged to support the VSx assignment, including X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure spectroscopy, selected area electron diffraction, and X-ray diffraction measurements. The VS2 annealing step reduces the oxide character and generates VSx, which, based on the improved NO3RR activity, results in the creation of active sites for NO3- binding. To help shed light on NO3RR on VSx, VS2 is used as a model system, and a grand-canonical density functional theory (GC-DFT) investigation of VS2 shows strong evidence that S vacancies are active sites for NO3RR, where NO3- outcompetes H+ for adsorption at the S-vacancy sites. Moreover, GC-DFT results highlight a thermodynamically favorable reaction to generate NH4+ in an aqueous electrolyte at relevant cathodic potentials. As an annealed material, VSx may contain undersaturated V sites, which show an electronic structure similar to the theoretically calculated S-vacancy site of VS2, and these sites may contribute to the observed increase in NO3RR activity and selectivity for NH4+ on VSx versus unannealed VS2. Finally, kinetic isotope effect measurements suggest that the kinetic rate-limiting step of the NO3RR on VSx is not proton-coupled, indicating it may be the first electron transfer to adsorbed NO3*.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2004

Resistance exercise as a countermeasure to disuse-induced bone loss

During spaceflight, skeletal unloading results in loss of bone mineral density (BMD). This occurs primarily in the spine and lower body regions. This loss of skeletal mass could prove hazardous to astronauts on flights of long duration. In this study, intense resistance exercise was used to test whether a training regimen would prevent the loss of BMD that accompanies disuse. Nine subjects (5 men, 4 women) participated in a supine maximal resistance exercise training program during 17 wk of horizontal bed rest. These subjects were compared with 18 control subjects (13 men, 5 women) who followed the same bed rest protocol without exercise. Determination of treatment effect was based on measures of BMD, bone metabolism markers, and calcium balance obtained before, during, and after bed rest. Exercisers and controls had significantly (P < 0.05) different means, represented by the respective following percent changes: lumbar spine BMD, +3% vs. -1%; total hip BMD, +1% vs. -3%; calcaneus BMD, +1% vs. -9%; pelvis BMD, -0.5% vs. -3%; total body BMD, 0% vs. -1%; bone-specific alkaline phosphatase, +64% vs. 0%; alkaline phosphatase, +31% vs. +5%; osteocalcin, +43% vs. +10%; 1,25 dihydroxyvitamin D, +12% vs. -15%; parathyroid hormone intact molecule, +18% vs. -25%; and serum and ionized calcium, -1% vs. +1%. The difference in net calcium balance was also significant (+21 mg/day vs. -199 mg/day, exercise vs. control). The gastrocnemius and soleus muscle volumes decreased significantly in the exercise group, but the loss was significantly less than observed in the control group. The results indicate that resistance exercise had a positive treatment effect and thus might be useful as a countermeasure to prevent the deleterious skeletal changes associated with long-duration spaceflight.

Clinical Trial↗
NASA NTRS2001

Exercise Thermoregulation Following 13 Days of Bed Rest

This investigation examined two potential mechanisms, altered skin blood flow (SBF) and sweating rate (SR) responses, that may be responsible for an elevated core temperature during exercise after bed rest (BR) and space flight. Seven healthy men (29 +/- 5 yr, 179.6 +/- 7.1 cm, 77.2 +/- 17.0kg; mean +/- SD) underwent 13 days of 6 deg head-down BR. Pre- and post-BR, subjects completed supine submaximal cycle ergometry (20 min at 40% and 20 min at 65% of pre-BR supine VO2pk) in a thermoneutral room (23.4 +/- 0.5 C, 56 +/- 8 %RH) during, heat production (VO2 ; indirect calorimetry), intestinal temperature (T(sub in) ; ingestible pill), SBF (laser Doppler velocimetry), local SR (dew point hygrometry), and total sweat loss (TSL; Delta body weight) were measured. Pre- and post- BR plasma volume (PV) was measured using I-125 dilution. After BR, T(sub in) was elevated at rest (36.99 +/- 0.14 vs. 37.30 +/- 0.06 C; p<_0.05) and at the end of exercise (37.57 +/- 0.13 vs. 37.90 +/- 0.09 C; P less than or equal to 0.05). However, the increase in T(sub in) from rest to the end of exercise was not different after BR (0.59 +/- 0.07 vs. 0.60 +/- 0.07 C). There was no difference in VO2 pre- to post-BR during rest (0.28 +/- 0.04 vs. 0.24 +/- 0.03 1 multiplied by min(exp -1) ) or 40% VO2pk (0.95 +/- 0.08 vs. 0.96 +/- 0.05 1 multiplied by min(exp -1)), but VO2 was significantly less at the end of the 65% VO2pk stage (1.53 +/- 0.09 vs. 1.42 +/- 0.11 1 multiplies by min(exp - 1); p less than or equal to 0.05). The percent change in SBF from rest to end of exercise was less after BR (211 +/- 53 vs. 96 +/- 31%; p less than or equal to 0.05), the threshold for the onset of SBF was greater (37.17 +/- 0.18vs. 37.51 +/- 0.17 C; p less than or equal to 0.05), and the slope of the response tended to be reduced (536 +/- 184 vs. 201 +/- 46 %A PC; p=0.08). TSL was not different after BR (0.42+0.06 vs. 0.44 +/- 0.08 kg), but the T in threshold at the onset of sweating was delayed significantly (37.06 +/- 0.1 1 vs. 37.34 +/- 0.06 C; p less than or equal to 0.05). However, the slope of SR was not changed after BR (3.45 +/- 1.22 vs. 2.58 +/- 0.71 mg multiplied by min(exp -1) multiplied by cm sq). PV was decreased by 11% after BR (3,259 +/- 177 vs. 2,894 +/- 138 ml; p less than or equal to 0.05). These results suggest that exercise SBF and SR responses after BR are altered, and heat production is unchanged or reduced, consistent with observations following space flight. The higher resting T(sub in) with a proportional increase in T(sub in) during exercise and delayed onset of SBF and SR suggest a centrally-mediated elevation in the thermoregulatory set point during microgravity exposure.

Lee, Stuart M. C.↗
NASA NTRS1975

ECASTAR: Energy conservation. An assessment of systems, technologies and requirements

A methodology was presented for a systems approach to energy conservation actions and their potentials and impacts in the United States. Constraints affecting the approach were ranked, and the most important ones are the present economic and technical conditions. The following unresolved issues were identified: consumptive lifestyles vs. conservation ethic, environmental standards vs. energy conservation, capital availability, decentralization and vertical integration vs. centralization, fuel rich regions vs. fuel poor regions, supply vs. end use conservation, life cycle costing vs. initial cost, mandatory savings vs. voluntary savings, labor intensive vs. capital intensive, price control vs. free market. The following recommendations were made: provide action/impact assessment, establish regional energy centers, improve technology articulation with government, design total energy systems, utilize existing systems approach expertise.

Source record↗
NASA NTRS1996

Temperature Regulation in Crewmembers After a 115-Day Space Flight

Impaired thermoregulation, which has been observed during exercise following bed rest, may significantly impact crewmembers during space flight operations by decreasing exercise capacity and orthostatic tolerance. Impaired temperature regulation would cause higher levels of core temperature, due to an attenuated cutaneous vasodilatory reflex and sweating response, for a given oxygen consumption. Two mate crewmembers of the Mir 18 mission performed supine cycle exercise se (20 min @ 40% and 20 min @ 65% preflight VO2pk) 145 days preflight and 5 days postflight. Core temperature (Tcore) was measured by an ingestible telemetry pill, skin blood flow (SBF) by laser Doppler velocimetry, and sweat rate (SR) by dew point hygrometry. Tcore at the time of test termination was similar (37.8 C) for both subjects before and after flight despite a shorter test duration (40 vs 28-29 minutes) postflight. The slopes of the SBF/Tcore relationship (Subj 1: 396 vs 214; Subj 2: 704 vs 143 Perfusion Unit/degC) and SR/Tcore relationship (Subj 1: 4.5 vs 2.1; Subj 2: 11.0 vs 3.6mg/min/sq cm/degC) were reduced postflight. Tcore thresholds for both SR (Subj 1: 37.4 vs 37.6; Subj 2: 37.6 vs 37.6 C) and SBF (Subj 1: 37.3 vs 37.5; Subj 2: 37.6 vs 37.7 C) were similar pre- to postflight. For these 2 crewmembers, it appeared that thermoregulation during exercise was impaired as evidenced by compromised heat loss responses after long-duration space flight.

Lee, S. M. C.↗
NASA NTRS1992

Impaired bone formation in male idiopathic osteoporosis: further reduction in the presence of concomitant hypercalciuria

We present iliac bone histomorphometric data and related biochemical data from 16 nonalcoholic men (50 +/- 11 (SD) years) referred for evaluation of spontaneous skeletal and/or appendicular fractures and reduced spinal bone density. All men were eugonadal and had no known underlying disorder associated with osteopenia. For the group, mean serum chemistry values were within normal limits including immunoreactive parathyroid hormone, osteocalcin and serum 1,25-dihydroxyvitamin D [1,25(OH)2D]. Nine men demonstrated hypercalciuria (greater than or equal to 0.1 mmol/kg per day) while on a constant metabolic diet of 20 mmol/day Ca. Their 24-hour urinary calcium was significantly greater than that for the remaining 7 men (7.4 +/- 1.6 vs. 5.0 +/- 0.8 mmol/day, p = 0.003), as was their calciuric response to a 1 g oral calcium load (0.23 +/- 0.06 vs. 0.15 +/- 0.05 Ca/creatinine, p = 0.042). Serum parameters (including parathyroid hormone and 1,25(OH)2D) of hypercalciuric and normocalciuric men were not significantly different. Histomorphometric indices for cancellous bone demonstrated significant differences between the entire group of osteoporotic men and age-adjusted normal values for bone volume (11.4 +/- 4.0% vs. 23.2 +/- 4.4%), osteoid surface (5.6 +/- 3.9% vs. 12.1 +/- 4.6%), osteoblastic surface (2.0 +/- 2.3% vs. 3.9 +/- 1.9%), and mineralizing surface (1.9 +/- 2.4% vs. 5.1 +/- 2.7%); there were also significant differences in bone formation rate (total surface referent) (0.004 +/- 0.001 vs. 0.011 +/- 0.006 mm3/mm2 per year). Compared with the normocalciuric group the 9 hypercalciuric men had significantly lower osteoblastic surfaces (1.6 +/- 1.9% vs. 2.5 +/- 2.6%) and mineralizing surfaces (1.4 +/- 1.5% vs. 2.7 +/- 3.2%).(ABSTRACT TRUNCATED AT 250 WORDS).

NASA Discipline Regulatory Physiology↗
NASA NTRS2023

Relationship Between the Sub-Micron Fraction (SMF) and Fine-Mode Fraction (FMF) in the Context of AERONET Retrievals

The sub-micron (SM) aerosol optical depth (AOD) is an optical separation based on the fraction of particles below a specified cutoff radius of the particle size distribution (PSD) at a given particle radius. It is fundamentally different from spectrally separated FM (fine-mode) AOD. We present a simple (AOD-normalized) SM fraction versus FM fraction (SMF vs. FMF) linear equation that explains the well-recognized empirical result of SMF generally being greater than the FMF. The AERONET inversion (AERinv) products (combined inputs of spectral AOD and sky radiance) and the spectral deconvolution algorithm (SDA) products (input of AOD spectra) enable, respectively, an empirical SMF vs. FMF comparison at similar (columnar) remote sensing scales across a variety of aerosol types. SMF (AERinv-derived) vs. FMF (SDA-derived) behavior is primarily dependent on the relative truncated portion (ε c ) of the coarse-mode (CM) AOD associated with the cutoff portion of the CM PSD and, to a second order, the cutoff FM PSD and FM AOD (ε f ). The SMF vs. FMF equation largely explains the SMF vs. FMF behavior of the AERinv vs. SDA products as a function of PSD cutoff radius (“inflection point”) across an ensemble of AERONET sites and aerosol types (urban-industrial, biomass burning, dust, maritime and a mixed class of Arctic aerosols). The overarching dynamic was that the linear SMF vs. FMF relation pivots clockwise about the approximate (SMF, FMF) singularity of (1, 1) in a “linearly inverse” fashion (slope and intercept of approximately 1−ε c and ε c ) with increasing cutoff radius. SMF vs. FMF slopes and intercepts derived from AERinv and SDA retrievals confirmed the general domination of ε c over ε f in controlling that dynamic. A more general conclusion is the apparent confirmation that the optical impact of truncating modal (whole) PSD features can be detected by an SMF vs. FMF analysis.

Norman T. O'Neill↗
DOE OSTI2020

Risk‐based, response‐adapted therapy for early‐stage extranodal nasal‐type NK /T‐cell lymphoma in the modern chemotherapy era: A China Lymphoma Collaborative Group study

Abstract We aimed to determine the survival benefits of chemotherapy (CT) added to radiotherapy (RT) in different risk groups of patients with early‐stage extranodal nasal‐type NK/T‐cell lymphoma (ENKTCL), and to investigate the risk of postponing RT based on induction CT responses. A total of 1360 patients who received RT with or without new‐regimen CT from 20 institutions were retrospectively reviewed. The patients had received RT alone, RT followed by CT (RT + CT), or CT followed by RT (CT + RT). The patients were stratified into different risk groups using the nomogram‐revised risk index (NRI). A comparative study was performed using propensity score‐matched (PSM) analysis. Adding new‐regimen CT to RT (vs RT alone) significantly improved overall survival (OS, 73.2% vs 60.9%, P < .001) and progression‐free survival (PFS, 63.5% vs 54.2%, P < .001) for intermediate‐risk/high‐risk patients, but not for low‐risk patients. For intermediate‐risk/high‐risk patients, RT + CT and CT + RT resulted in non‐significantly different OS (77.7% vs 72.4%; P = .290) and PFS (67.1% vs 63.1%; P = .592). For patients with complete response (CR) after induction CT, initiation of RT within or beyond three cycles of CT resulted in similar OS (78.2% vs 81.7%, P = .915) and PFS (68.2% vs 69.9%, P = .519). For patients without CR, early RT resulted in better PFS (63.4% vs 47.6%, P = .019) than late RT. Risk‐based, response‐adapted therapy involving early RT combined with CT is a viable, effective strategy for intermediate‐risk/high‐risk early‐stage patients with ENKTCL in the modern treatment era.

Qi, Shu‐Nan↗
DOE OSTI2020

A microbiological survey of handwashing sinks in the hospital built environment reveals differences in patient room and healthcare personnel sinks

Handwashing sinks and their associated premise plumbing are an ideal environment for pathogen-harboring biofilms to grow and spread throughout facilities due to the connected system of wastewater plumbing. This study was designed to understand the distribution of pathogens and antibiotic resistant organisms (ARO) within and among handwashing sinks in healthcare settings, using culture-dependent methods to quantify Pseudomonas aeruginosa, opportunistic pathogens capable of growth on a cefotaxime-containing medium (OPP-C), and carbapenem-resistant Enterobacteriaceae (CRE). Isolates from each medium identified as P. aeruginosa or Enterobacteriaceae were tested for susceptibility to aztreonam, ceftazidime, and meropenem; Enterobacteriaceae were also tested against ertapenem and cefotaxime. Isolates exhibiting resistance or intermediate resistance were designated ARO. Pathogens were quantified at different locations within handwashing sinks and compared in quantity and distribution between healthcare personnel (HCP) and patient room (PR) sinks. ARO were compared between samples within a sink (biofilm vs planktonic samples) and between sink types (HCP vs. PR). The drain cover was identified as a reservoir within multiple sinks that was often colonized by pathogens despite daily sink cleaning. P. aeruginosa and OPP-C mean log 10 CFU/cm 2 counts were higher in p-trap and tail pipe biofilm samples from HCP compared to PR sinks (2.77 ± 2.39 vs. 1.23 ± 1.62 and 5.27 ± 1.10 vs. 4.74 ± 1.06) for P. aeruginosa and OPP-C, respectively. P. aeruginosa and OPP-C mean log 10 CFU/ml counts were also higher (p < 0.05) in HCP compared to PR sinks p-trap water (2.21 ± 1.52 vs. 0.89 ± 1.44 and 3.87 ± 0.78 vs. 3.21 ± 1.11) for P. aeruginosa and OPP-C, respectively. However, a greater percentage of ARO were recovered from PR sinks compared to HCP sinks (p < 0.05) for Enterobacteriaceae (76.4 vs. 32.9%) and P. aeruginosa (25.6 vs. 0.3%). This study supports previous work citing that handwashing sinks are reservoirs for pathogens and ARO and identifies differences in pathogen and ARO quantities between HCP and PR sinks, despite the interconnected premise plumbing.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2026

Predictive analytics to direct clinical attention to complex patients with elevated suicide risk: enhancement of the Veterans Health Administration REACH VET model

Suicide is a major public health concern, particularly among Veterans. The U.S. Department of Veterans Affairs Veterans Health Administration (VHA) employs the Recovery Engagement and Coordination for Health–Veterans Enhanced Treatment (REACH VET) model to prioritise high-risk patients for targeted clinical attention. REACH VET 1.0 (RV 1.0) was developed on 2008–2011 data. To reflect changes in clinical practice and populations, VHA updated it to REACH VET 2.0 (RV 2.0). This study describes its development and validation. RV 2.0 used longitudinal data from 7,248,170 VHA patients (4,967 suicide deaths) in 2018–2019, with 650 time-varying demographic, clinical and area-level predictors derived from a 2-year lookback (2016–2019). An ensemble of Elastic-Net logistic regression models was trained on 2018 data and evaluated monthly at the population level in 2019, focusing on the top 0.1% intervention risk tier. Analyses assessed model discrimination, suicide detection, risk concentration, subgroup consistency (sex, age and race/ethnicity) and performance relative to RV 1.0 using the same percentile-based risk strata. RV 2.0 outperformed RV 1.0 across all risk strata, with better discrimination (C-statistic 0.76 vs 0.69) and consistent performance across demographic subgroups. Within the top 0.1% of predicted risk, RV 2.0 identified more deaths, higher suicide rates and greater mortality risk concentration both when averaged across the 12 monthly 2019 test sets (5.6 vs 3.6; 83.6 vs 53.7 per 100,000 person-years; 21.0 vs 14.1) and when annualised for 2019 (67 vs 43; 2.7% vs 1.7%; 1,003 vs 644 per 100,000 person-years; 26.7 vs 17.1). RV 2.0 improves suicide risk stratification among Veterans, demonstrating better performance and consistent prediction across subgroups and highlighting the need for regular model updates and evaluation.

Peluso, Alina [Oak Ridge National Laboratory (ORNL↗
NASA NTRS2002

Body Composition of Rats on NASA Rodent Foodbar Versus Purina Lab Chow

The objective of this study is to test the nutritional adequacy of the NASA Rodent Foodbar for long term use for rats. The Foodbar was tested on two rat strains, Sprague Dawley and Fischer 344. Rats were fed either Foodbar or the control diet, Purina Chow #5012. Body composition analysis was performed on a selected number of samples (n=6 for each gender and treatment group) as part of extensive testing of the Foodbar. Water, fat, ash, and protein (and their percentages) for both treatment groups were compared. Sprague Dawley Foodbar fed rats had a lower % protein than Chow fed rats (25.8% vs. 30.0%). In addition, Sprague Dawley females fed Foodbar had higher total fat (42.1g vs. 24.6g) and % fat (16.4% vs. 10.5%), but lower % water (51.3% vs. 54.8%) than Sprague Dawley females fed Chow. Fischer 344 Foodbar fed rats had a lower % water (47.4% vs. 49,3%) and total water (93.2g vs. 99.6g). In addition, Fischer 344 Foodbar males had higher % fat (17.0% vs. 13.8%) and total fat (43.0g vs. 34.7g). The data suggests that body composition of Foodbar fed rats tends to have lower water content but a higher fat content compared to controls, but not all results are the same for different strains and even different genders within the same strains. The data obtained here, in addition to other data, helps provide a better understanding of the nutritional adequacy of the Foodbar and whether the formula may need to be modified.

Yu, Diane Sau Mun↗