Search NASA⌕ Search

SEARCH · Search NASA

Results for “oxidation capacity”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Spectral reflectance of surface soils: Relationships with some soil properties

Using a published atlas of reflectance curves and physicochemical properties of soils, a statistical analysis was carried out. Reflectance bands which correspond to five of the wavebands used by NASA's Thematic Mapper were examined for relationships to specific soil properties. The properties considered in this study include: Sand Content, Silt Content, Clay Content, Organic Matter Content, Cation Exchange Capacity, Iron Oxide Content and Moisture Content. Regression of these seven properties on the mean values of five TM bands produced results that indicate that the predictability of the properties can be increased by stratifying the data. The data was stratified by parent material, taxonomic order, temperature zone, moisture zone and climate (combined temperature and moisture). The best results were obtained when the sample was examined by climatic classes. The middle Infra-red bands, 5 and 7, as well as the visible bands, 2 and 3, are significant in the model. The near Infra-red band, band 4, is almost as useful and should be included in any studies. General linear modeling procedures examined relationships of the seven properties with certain wavebands in the stratified samples.

Kiesewetter, C. H.↗
NASA NTRS2003

Sera from cancer patients contain two oscillating ECTO-NOX activities with different period lengths

ECTO-NOX protein's are cell surface-associated and growth-related hydroquinone oxidases with both protein disulfide-thiol interchange activity and the capacity to oxidize NAD(P)H. The activities of these ECTO-NOX proteins are not steady state but fluctuate to create a repeating pattern of oscillations. Two forms of ECTO-NOX activities have been distinguished. The constitutive ECTO-NOX (CNOX), is hormone responsive and refractory to quinone-site inhibitors. A tumor-associated NOX (tNOX) is unregulated, refractory to hormones and growth factors and responds to quinone-site inhibitors. CNOX proteins are widely distributed and exhibit oscillations in enzymatic activity with a period length of 24 min. tNOX proteins are cancer specific and exhibit oscillations with a period length of about 22 min. Our findings now demonstrate the presence of the novel oscillating tNOX activity in sera of patients with cancer whereas the constitutive NOX of non-cancer cells is present in sera of both cancer patients and healthy volunteers. We conclude that ECTO-NOX proteins in sera exhibit oscillatory characteristics similar to those of ECTO-NOX forms of the cell surface.

NASA Discipline Cell Biology↗
NASA NTRS2000

Effect of spaceflight on the maximal shortening velocity, morphology, and enzyme profile of fast- and slow-twitch skeletal muscle fibers in rhesus monkeys

Weightlessness has been shown to cause limb muscle wasting and a reduced peak force and power in the antigravity soleus muscle. Despite a reduced peak power, Caiozzo et al. observed an increased maximal shortening velocity in the rat soleus muscle following a 14-day space flight. The major purpose of the present investigation was to determine if weightlessness induced an elevated velocity in the antigravity slow type I fibers of the rhesus monkey (Macaca mulatta), as well as to establish a cellular mechanism for the effect. Spaceflight or models of weightlessness have been shown to increase glucose uptake, elevate muscle glycogen content, and increase fatigability of the soleus muscle. The latter appears to be in part caused by a reduced ability of the slow oxidative fibers to oxidize fats. A second goal of this study was to establish the extent to which weightlessness altered the substrate profile and glycolytic and oxidative enzyme capacity of individual slow- and fast-twitch fibers.

Bion 11 Project↗
NASA NTRSDate not supplied

Airborne observations in support of a satellite observation-based OH product

This presentation outlines work to date analyzing airborne observations to improve a satellite observation-based hydroxyl radical (OH) column product by interrogating model chemistry processes. Anderson et al., 2023, established a machine learning method to combine satellite observations of O3, CO, NO2, HCHO, H2O, and aerosol optical depth, along with analyzed sea surface temperatures, for the prediction of tropospheric column OH (TCOH). Since the TCOH machine learning model was trained on output from the MERRA-2 GMI model simulation, we seek to identify if any model deficiencies may yield errors in the TCOH prediction. By evaluating F0AM box model simulations and neural networks trained to reproduce in situ OH concentrations, together with output reaction rates and interpretability metrics, respectively, we validate the Anderson et al. TCOH model and assess the largest contributors to uncertainties.

Hydroxyl, oxidizing capacity, troposphere, airborn↗
NASA NTRS1983

Effect of denervation and reinnervation on oxidation of 6-(C-14) glucose by rat skeletal muscle homogenates

The effects of denervation and reinnervation of the rat extensor digitorum longus muscle on the oxidation of 6-(C-14) glucose to (C-14)O2 is investigated. Results show that the rate of (C-14)O2 production decreased dramatically following denervation and the decrease became significant 20 days after nerve section. The changes which occurred prior to day 20 apparently reflected the decline of muscle mass. The decreased (C-14)O2 production was found to be due to reduced capacity of the enzymatic system, while there was no change in the apparent affinity for glucose. Results of mixing experiments showed that the loss of oxidative capacity following denervation is not caused by the production of soluble inhibitors by degenerating muscle. Measurements of the (C-14)O2 revealed that oxidative metabolism recovered during reinnervation. The specific activity in reinnervated muscles displayed an 'overshoot' of approximately 50 percent, which returned to control levels by day 60. The time-course of the denervation-mediated change indicates that altered oxidative capacity is secondary to events that initiate dennervation changes in muscle, although diminished oxidative capacity may be of considerable metabolic significance in denervated muscle.

Dubois, D. C.↗
NASA NTRS1978

Two braze alloys for thin-wall components

Alloys are ductile and are not subject to hydrogen or cryogenic embrittlement. During brazing operation, alloys demonstrate excellent wetting, flow and gap-filling capacities, and resist oxidation and salt-spray corrosion. Alloys are producible as foils, tape, wire, and powder. They may be used to join stainless steels and nickel and cobalt high-temperature alloys.

Brennan, A.↗
NASA NTRS2000

Physiology of a microgravity environment invited review: microgravity and skeletal muscle

Spaceflight (SF) has been shown to cause skeletal muscle atrophy; a loss in force and power; and, in the first few weeks, a preferential atrophy of extensors over flexors. The atrophy primarily results from a reduced protein synthesis that is likely triggered by the removal of the antigravity load. Contractile proteins are lost out of proportion to other cellular proteins, and the actin thin filament is lost disproportionately to the myosin thick filament. The decline in contractile protein explains the decrease in force per cross-sectional area, whereas the thin-filament loss may explain the observed postflight increase in the maximal velocity of shortening in the type I and IIa fiber types. Importantly, the microgravity-induced decline in peak power is partially offset by the increased fiber velocity. Muscle velocity is further increased by the microgravity-induced expression of fast-type myosin isozymes in slow fibers (hybrid I/II fibers) and by the increased expression of fast type II fiber types. SF increases the susceptibility of skeletal muscle to damage, with the actual damage elicited during postflight reloading. Evidence in rats indicates that SF increases fatigability and reduces the capacity for fat oxidation in skeletal muscles. Future studies will be required to establish the cellular and molecular mechanisms of the SF-induced muscle atrophy and functional loss and to develop effective exercise countermeasures.

short duration↗
NASA NTRS2020

JSC-Rocknest: A Large-Scale Mojave Mars Simulant (MMS) Based Soil Simulant for In-Situ Resource Utilization Water-Extraction Studies

The Johnson Space Center-Rocknest (JSC-RN) simulant was developed in response to a need by NASA's Advanced Exploration Systems (AES) In-Situ Resource Utilization (ISRU) project for a simulant to be used in component and system testing for water extraction from Mars regolith. JSC-RN was designed to be chemically and mineralogically similar to material from the aeolian sand shadow named Rocknest in Gale Crater, particularly the 1-3 wt.% low temperature (<450 ºC) water release as measured by the Sample Analysis at Mars (SAM) instrument on the Curiosity rover. Sodium perchlorate, goethite, pyrite, ferric sulfate, regular and high capacity granular ferric oxide, and forsterite were added to a Mojave Mars Simulant (MMS) base in order to match the mineralogy, evolved gases, and elemental chemistry of Rocknest. Mineral and rock components were sent to the United States Geological Survey (USGS) in Denver for mixing. Approximately 800 kg of JSC-RN was sent back to NASA in 5 gallon buckets, which were subsampled and characterized. All samples of the USGS-produced simulants had similar evolved gas profiles as a small prototype batch of JSC-RN made in JSC laboratories, with the exception of HCl, and were similar in terms of mineralogy and total chemistry. Also, all JSC-RN subsamples were homogenous and had similar mineralogy, total chemistry, and low-temperature evolved gas profiles as the Rocknest aeolian sand shadow examined with Curiosity’s instrument suite on Mars. In particular, the low temperature water releases were similar and the amount of water evolved from JSC-RN at <450 ºC was similar to the water content of Rocknest based on SAM water peak integrations. Overall, JSC-RN is ideally suited for ISRU studies of water extraction of global martian soil due to its excellent agreement with measured properties of martian soils and its proven feasibility for large-scale production.

Simulant↗
NASA NTRSDate not supplied

A Two-Stage Regenerable Filter for Collection and Disposal of Carbon Fines

NASA is investigating the use of the Plasma Pyrolysis Assembly (PPA), which is a methane post-processing technology with the goal to recover hydrogen from the Carbon dioxide Reduction Assembly (CRA) currently onboard the International Space Station (ISS). The PPA can theoretically recover 75% of hydrogen from methane produced by the CRA. During methane processing the PPA creates roughly 40 mg/hr of carbon dust when operating at 4 crew member levels. The unwanted fines need to be removed from the stream to prevent any clogging of downstream components. The Regenerable Carbon Filter (RCF) was designed by Umpqua Research Company to address the carbon particulate created in the PPA. The RCF includes two stages. The first is an electrostatic precipitator designed to collect ultrafine particles. The second is a low pressure drop physical filter. Both filters are made of heat tolerant materials to allow regeneration of the filtration capacity by O2 oxidation of captured carbon. This paper will discuss the RCF hardware and test plans.

Filtration, Environmental Control, Life Support↗
NASA NTRS1996

Relation of systemic and local muscle exercise capacity to skeletal muscle characteristics in men with congestive heart failure

OBJECTIVES. The present study was undertaken to further characterize changes in skeletal muscle morphology and histochemistry in congestive heart failure and to determine the relation of these changes to abnormalities of systemic and local muscle exercise capacity. BACKGROUND. Abnormalities of skeletal muscle appear to play a role in the limitation of exercise capacity in congestive heart failure, but information on the changes in muscle morphology and biochemistry and their relation to alterations in muscle function is limited. METHODS. Eighteen men with predominantly mild to moderate congestive heart failure (mean +/- SEM New York Heart Association functional class 2.6 +/- 0.2, ejection fraction 24 +/- 2%) and eight age- and gender-matched sedentary control subjects underwent measurements of peak systemic oxygen consumption (VO2) during cycle ergometry, resistance to fatigue of the quadriceps femoris muscle group and biopsy of the vastus lateralis muscle. RESULTS. Peak VO2 and resistance to fatigue were lower in the patients with heart failure than in control subjects (15.7 +/- 1.2 vs. 25.1 +/- 1.5 ml/min-kg and 63 +/- 2% vs. 85 +/- 3%, respectively, both p < 0.001). Patients had a lower proportion of slow twitch, type I fibers than did control subjects (36 +/- 3% vs. 46 +/- 5%, p = 0.048) and a higher proportion of fast twitch, type IIab fibers (18 +/- 3% vs. 7 +/- 2%, p = 0.004). Fiber cross-sectional area was smaller, and single-fiber succinate dehydrogenase activity, a mitochondrial oxidative marker, was lower in patients (both p < or = 0.034). Likewise, the ratio of average fast twitch to slow twitch fiber cross-sectional area was lower in patients (0.780 +/- 0.06 vs. 1.05 +/- 0.08, p = 0.019). Peak VO2 was strongly related to integrated succinate dehydrogenase activity in patients (r = 0.896, p = 0.001). Peak VO2, resistance to fatigue and strength also correlated significantly with several measures of fiber size, especially of fast twitch fibers, in patients. None of the skeletal muscle characteristics examined correlated with exercise capacity in control subjects. CONCLUSIONS. These results indicate that congestive heart failure is associated with changes in the characteristics of skeletal muscle and local as well as systemic exercise performance. There are fewer slow twitch fibers, smaller fast twitch fibers and lower succinate dehydrogenase activity. The latter finding suggests that mitochondrial content of muscle is reduced in heart failure and that impaired aerobic-oxidative capacity may play a role in the limitation of systemic exercise capacity.

Non-NASA Center↗
NASA NTRS1982

Development works on nickel/hydrogen cells

Experiments were performed to reduce the costs for NI/H2 cells by using nickel oxide electrodes with high capacity per unit area. No maintenance requirements, long cycle life, insensitivity to overcharge and cell reversal, and high power capability were revealed.

Gutmann, G.↗
NASA NTRS2002

Interactions between muscle and the immune system during modified musculoskeletal loading

Interactions between the immune system and skeletal muscle may play a significant role in modulating the course of muscle injury and repair after modified musculoskeletal loading. Current evidence indicates that activation of the complement system is an early event during modified loading, which then leads to inflammatory cell invasion. However, the functions of those inflammatory cells are complex and they seem to be capable of promoting additional injury and repair. Recent findings implicate an early invading neutrophil population in increasing muscle damage that is detected by the presence of muscle membrane lesions. Macrophages that invade subsequently serve to remove cellular debris, and seem to promote repair. However, macrophages also have the ability to increase damage in muscle in which there is an impaired capacity to generate nitric oxide. In vivo and in vitro evidence indicates that muscle-derived nitric oxide can serve an important role in protecting muscle from membrane damage by invading inflammatory cells. Collectively, these findings indicate that the dynamic balance between inflammatory cells, the complement system, and muscle-derived free radicals can play important roles in the secondary damage of muscle during modified musculoskeletal loading.

Review↗
NASA NTRS1974

Contaminant removal from enclosed atmospheres by regenerable adsorbents

A system for removing contaminants from spacecraft atmospheres was studied, which utilizes catalyst-impregnated activated carbon followed by in-situ regeneration by low-temperature catalytic oxidation of the adsorbed contaminants. Platinum was deposited on activated carbon by liquid phase impregnation with chloroplatinic acid, followed by drying and high-temperature reduction. Results were obtained for the seven selected spacecraft contaminants by means of three experimental test systems. The results indicate that the contaminants could be removed by oxidation with very little loss in adsorptive capacity. The advantages of a catalyst-impregnated carbon for oxidative regeneration are found to be significant enough to warrent its use.

Goldsmith, R. L.↗
NASA NTRS1973

Heat-sterilized silver oxide-zinc cells: Cycle life studies

A JPL study was conducted to evaluate the cell design parameters that contribute to the cycle life of sealed, heat-sterilized silver oxide-zinc cells. Test cells having a rated capacity of 4.2 A-h were fabricated using zinc oxide electrodes prepared by the sintered Teflon process. Two separator variations were evaluated, one having acrylic acid and the other methacrylic acid grafted to irradiated polyethylene film. Significant results of this study include the following: (1) cycle life in excess of 300 cycles was attained; (2) a zinc oxide/silver stoichiometric ratio of 1.5 resulted in greater cycle life than a ratio of 1.1, and similar cycle life to cells having a ratio of 2; (3) cells having methacrylic acid grafted separators suffered somewhat less in capacity loss due to zinc electrode shape change than cells having acrylic acid type; (4) use of acrylic acid grafted separators was slightly superior to the methacrylic acid type in respect to silver penetration; and (5) the inclusion of a layer of potassium titanate paper adjacent to the zinc electrodes resulted in cells that achieved higher cycle life before any of the group failed than that reached by cells of any other construction.

Arms, J. T.↗
NASA NTRS1981

Degradation of a two-layer thermal barrier coating under thermal cycling

A two-layer plasma-sprayed thermal barrier coating on a directionally solidified nickel-base eutectic alloy substrate was characterized prior to and after thermal cycling to 1095 C in an accelerated furnace test. The coating was comprised of an inner layer of Ni-16.4Cr-5.1Al-0.15Y (wt%) bond coat and an outer layer of ZrO2-7.9Y2O3 (wt%) thermal barrier. Characterization of the bond coat revealed that substantial amounts of yttrium and aluminum were oxidized during plasma-spraying in air. The oxidation of these elements reduced the protective capacity of the bond coat so that, on thermal exposure, severe degradation of the bond coat resulted and large amounts of nickel oxide formed. This nickel oxide was demonstrated to grow outward into the thermal barrier, which appears to have increased the stresses in the thermal barrier and contributed to its failure near the thermal barrier-bond coat interface.

Maier, R. D.↗
NASA NTRS2000

Effects of Carbon Structure and Surface Oxygen on the Carbon's Performance as the Anode in Lithium-Ion Battery Determined

Four carbon materials (C1, C2, C3, and C4) were tested electrochemically at the NASA Glenn Research Center at Lewis Field to determine their performance in lithium-ion batteries. They were formed as shown in the figure. This process caused very little carbon loss. Products C1 and C3 contained very little oxygen because of the final overnight heating at 540 C. Products C2 and C4, on the other hand, contained small amounts of basic oxide. The electrochemical test involved cycles of lithium intercalation and deintercalation using C/saturated LiI-50/50 (vol %) ethylene carbonate (EC) and dimethyl carbonate (DMC)/Li half cell. The cycling test, which is summarized in the table, resulted in three major conclusions. The capacity of the carbon with a basic oxide surface converges to a constant 1. value quickly (within 4 cycles), possibly because the oxide prevents solvent from entering the carbon structure and, therefore, prolongs the carbon s cycle life. Under certain conditions, the disordered carbon can store more lithium than its 2. precursor. These samples and their precursor can intercalate at 200 mA/g and deintercalate at 3. a rate of 2000 mA/g without significant capacity loss.

Hung, Ching-Cheh↗
NASA NTRS2016

Microorganisms, Organic Carbon, and Their Relationship with Oxidant Activity in Hyper-Arid Mars-Like Soils: Implications for Soil Habitability

Soil samples from the hyper-arid region in the Atacama 23 Desert in Southern Peru (La Joya Desert) were analyzed for total and labile organic carbon (TOC & LOC), phospholipid fatty acids analysis (PLFA), quantitative real time polymerase chain reaction (qRT-PCR), 4',6- diamidino-2-phenylindole (DAPI)-fluorescent microscopy, culturable microorganisms, and oxidant activity, in order to understand the relationship between the presence of organic matter and microorganisms in these types of soils. TOC content levels were similar to the labile pool of carbon suggesting the absence of recalcitrant carbon in these soils. The range of LOC was from 2 to 60 micro-g/g of soil. PLFA analysis indicated a maximum of 2.3 x 10(exp 5) cell equivalents/g. Culturing of soil extracts yielded 1.1 x 10(exp 2)-3.7 x 10(exp 3) CFU/g. qRT-PCR showed between 1.0 x 10(exp 2) and 8 x 10(exp 3) cells/g; and DAPI fluorescent staining indicated bacteria counts up to 5 x 104 cells/g. Arid and semiarid samples (controls) showed values between 10(exp 7) and 10(exp 11) cells/g with all of the methods used. Importantly, the concentration of microorganisms in hyper-arid soils did not show any correlation with the organic carbon content; however, there was a significant dependence on the oxidant activity present in these soil samples evaluated as the capacity to decompose sodium formate in 10 hours. We suggest that the analysis of oxidant activity could be a useful indicator of the microbial habitability in hyper-arid soils, obviating the need to measure water activity over time. This approach could be useful in astrobiological studies on other worlds.

Mars-like soils↗