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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Changes in Interfacial Tension with Time in Two-Liquid-Phase Systems

Interfacial tension (IFT) is a thermodynamic property of the interface between two immiscible fluids. This property has been identified as an important factor in an advanced solvent extraction system because it correlates with settling time and miscibility. The IFT in a variety of two phase systems has been partially characterized by Los Alamos National Laboratory (LANL) scientists. Information about the change in IFT is gathered in this study to more fully characterize these two-phase systems. Metal loaded aqueous solutions are of particular interest, as they simulate a solvent extraction system. Based in part on this body of research, LANL scientists will select the appropriate organic solvent and aqueous pH to develop an advanced solvent extraction system which will remove heavy metals from acidic solutions. Previous studies show that the factor which has the greatest effect on discrete IFT measurements is the ratio of aqueous density to organic density1. It is expected that this density ratio will play an important role in time-dependent IFT measurements as well. The two phases will be brought into equilibrium before beginning the tests, so it is also expected that IFT will not drastically change over a two hour time period.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Soil organic matter availability and climate drive latitudinal patterns in bacterial diversity from tropical to cold temperate forests

Bacteria are one of the most abundant and diverse groups of micro-organisms and mediate many critical terrestrial ecosystem processes. Despite the crucial ecological role of bacteria, our understanding of their large-scale biogeography patterns across forests, and the processes that determine these patterns lags significantly behind that of macroorganisms. Here, we evaluated the geographic distributions of bacterial diversity and their driving factors across nine latitudinal forests along a 3,700-km north–south transect in eastern China, using high-throughput 16S rRNA gene sequencing. Four of 32 phyla detected were dominant: Acidobacteria , Actinobacteria , Alphaproteobacteria and Chloroflexi (relative abundance > 5%). Significant increases in bacterial richness and phylogenetic diversity were observed for temperate forests compared with subtropical or tropical forests. The soil organic matter (SOM) mineralisation rate (SOM min , an index of SOM availability) explained the largest significant variations in bacterial richness. Variation partition analysis revealed that the bacterial community structure was closely correlated with environmental variables and geographic distance, which together explained 80.5% of community variation. Among all environmental factors, climatic features (MAT and MAP) were the best predictors of the bacterial community structure, whereas soil pH and SOM min emerged as the most important edaphic drivers of the bacterial community structure. Plant functional traits (community weighted means of litter N content) and diversity resulted in weak but significant correlations with the bacterial community structure. Our findings provide new evidence of bacterial biogeography patterns from tropical to cold temperate forests. Additionally, the results indicated a close linkage among soil bacterial diversity, climate and SOM decomposition, which is critical for predicting continental-scale responses under future climate change scenarios and promoting sustainable forest ecosystem services.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2012

Optical Waveguide Lightmode Spectroscopy (OWLS) as a Sensor for Thin Film and Quantum Dot Corrosion

Optical waveguide lightmode spectroscopy (OWLS) is usually applied as a biosensor system to the sorption-desorption of proteins to waveguide surfaces. Here, we show that OWLS can be used to monitor the quality of oxide thin film materials and of coatings of pulsed laser deposition synthesized CdSe quantum dots (QDs) intended for solar energy applications. In addition to changes in data treatment and experimental procedure, oxide- or QD-coated waveguide sensors must be synthesized. We synthesized zinc stannate (Zn2SnO4) coated (Si,Ti)O2 waveguide sensors, and used OWLS to monitor the relative mass of the film over time. Films lost mass over time, though at different rates due to variation in fluid flow and its physical effect on removal of film material. The Pulsed Laser Deposition (PLD) technique was used to deposit CdSe QD coatings on waveguides. Sensors exposed to pH 2 solution lost mass over time in an expected, roughly exponential manner. Sensors at pH 10, in contrast, were stable over time. Results were confirmed with atomic force microscopy imaging. Limiting factors in the use of OWLS in this manner include limitations on the annealing temperature that maybe used to synthesize the oxide film, and limitations on the thickness of the film to be studied. Nevertheless, the technique overcomes a number of difficulties in monitoring the quality of thin films in-situ in liquid environments.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2000

Radiation-induced heat-labile sites that convert into DNA double-strand breaks

The yield of DNA double-strand breaks (DSBs) in SV40 DNA irradiated in aqueous solution was found to increase by more than a factor of two as a result of postirradiation incubation of the DNA at 50 degrees C and pH 8.0 for 24 h. This is in agreement with data from studies performed at 37 degrees C that were published previously. Importantly, similar results were also obtained from irradiation of mammalian DNA in agarose plugs. These results suggest that heat-labile sites within locally multiply damaged sites are produced by radiation and are subsequently transformed into DSBs. Since incubation at 50 degrees C is typically employed for lysis of cells in commonly used pulsed-field gel assays for detection of DSBs in mammalian cells, the possibility that heat-labile sites are present in irradiated cells was also studied. An increase in the apparent number of DSBs as a function of lysis time at 50 degrees C was found with kinetics that was similar to that for irradiated DNA, although the magnitude of the increase was smaller. This suggests that heat-labile sites are also formed in the cell. If this is the case, a proportion of DSBs measured by the pulsed-field gel assays may occur during the lysis step and may not be present in the cell as breaks but as heat-labile sites. It is suggested that such sites consist mainly of heat-labile sugar lesions within locally multiply damaged sites. Comparing rejoining of DSBs measured with short and long lysis procedure indicates that the heat-labile sites are repaired with fast kinetics in comparison with repair of the bulk of DSBs.

Non-NASA Center↗
NASA NTRS2008

Use of Potassium Citrate to Reduce the Risk of Renal Stone Formation During Spaceflight

Introduction: NASA s Vision for Space Exploration centers on exploration class missions including the goals of returning to the moon and landing on Mars. One of NASA s objectives is to focus research on astronaut health and the development of countermeasures that will protect crewmembers during long duration voyages. Exposure to microgravity affects human physiology and results in changes in the urinary chemical composition favoring urinary supersaturation and an increased risk of stone formation. Nephrolithiasis is a multifactorial disease and development of a renal stone is significantly influenced by both dietary and environmental factors. Previous results from long duration Mir and short duration Shuttle missions have shown decreased urine volume, pH, and citrate levels and increased calcium. Citrate, an important inhibitor of calcium-containing stones, binds with urinary calcium reducing the amount of calcium available to form stones. Citrate inhibits renal stone recurrence by preventing crystal growth, aggregation, and nucleation and is one of the most common therapeutic agents used to prevent stone formation. Methods: Thirty long duration crewmembers (29 male, 1 female) participated in this study. 24-hour urines were collected and dietary monitoring was performed pre, in, and postflight. Crewmembers in the treatment group received two potassium citrate (KCIT) pills, 10 mEq/pill, ingested daily beginning 3 days before launch, all inflight days and through 14 days postflight. Urinary biochemical and dietary analyses were completed. Results: KCIT treated subjects exhibited decreased urinary calcium excretion and maintained the levels of calcium oxalate supersaturation risk at their preflight levels. The increased urinary pH levels in these subjects reduced the risk of uric acid stones. Discussion: The current study investigated the use of potassium citrate as a countermeasure to minimize the risk of stone formation during ISS missions. Results suggest that supplementation with potassium citrate decreases the risk of stone formation during and immediately after spaceflight.

Whitson, P. A.↗
NASA NTRS2009

Renal Stone Risk during Spaceflight: Assessment and Countermeasure Validation

NASA's Vision for Space Exploration centers on exploration class missions including the goals of returning to the moon and landing on Mars. One of NASA's objectives is to focus research on astronaut health and the development of countermeasures that will protect crewmembers during long duration voyages. Exposure to microgravity affects human physiology and results in changes in the urinary chemical composition favoring urinary supersaturation and an increased risk of stone formation. Nephrolithiasis is a multifactorial disease and development of a renal stone is significantly influenced by both dietary and environmental factors. Previous results from long duration Mir and short duration Shuttle missions have shown decreased urine volume, pH, and citrate levels and increased calcium. Citrate, an important inhibitor of calcium-containing stones, binds with urinary calcium reducing the amount of calcium available to form stones. Citrate inhibits renal stone recurrence by preventing crystal growth, aggregation, and nucleation and is one of the most common therapeutic agents used to prevent stone formation. Methods: Thirty long duration crewmembers (29 male, 1 female) participated in this study. 24-hour urines were collected and dietary monitoring was performed pre-, in-, and postflight. Crewmembers in the treatment group received two potassium citrate (KCIT) pills, 10 mEq/pill, ingested daily beginning 3 days before launch, all in-flight days and through 14 days postflight. Urinary biochemical and dietary analyses were completed. Results: KCIT treated subjects exhibited decreased urinary calcium excretion and maintained the levels of calcium oxalate supersaturation risk at their preflight levels. The increased urinary pH levels in these subjects reduced the risk of uric acid stones. Discussion: The current study investigated the use of potassium citrate as a countermeasure to minimize the risk of stone formation during ISS missions. Results suggest that supplementation with potassium citrate decreases the risk of stone formation during and immediately after spaceflight.

Whitson, Peggy A.↗
NASA NTRS2002

Nutrition and renal stone disease in space

There is a growing body of evidence from the National Aeronautics and Space Administration and the Russian space program showing that humans exposed to the microgravity environment of space have a greater risk for developing renal stones. Increased bone resorption and the attendant hypercalciuria and hyperphosphaturia contribute significantly to raising the urinary state of saturation with respect to the calcium salts, namely calcium oxalate and calcium phosphate. In addition, other environmental and dietary factors may adversely affect urine composition and increase stone formation risk during space flight. For example, reductions in urinary volume, pH, and citrate contribute to raising stone formation risk. In addition to raising the risk for calcium stone formation, this metabolic profile is conducive to the formation of uric acid stones. Although observations to date have suggested that there may actually be a reduced food intake during the early phase of flight, crew members on longer-duration flights may increase food intake and be at increased risk for stone formation. Taken together, these findings support the use of nutritional recommendations for crew members that would serve to reduce the stone-forming propensity of the urinary environment. Pharmacologic intervention should be directed at raising urinary volumes, diminishing bone losses, and preventing reductions in urinary pH and citrate. Success in reducing the risk for stone formation in astronauts would also be of potential major benefit to the estimated 20 million Americans with nephrolithiasis.

Review↗
DOE OSTI2012

Synthesis and new structure shaping mechanism of silica particles formed at high pH

For the sol-gel synthesis of silica particles under high pH catalytic conditions (pH>12) in water/ethanol solvent, we have deduced that the competing dynamics of chemical etching and sol-gel process can explain the types of silica particles formed and their morphologies. We have demonstrated that emulsion droplets that are generated by adding tetraethyl orthosilicate (TEOS) to a water-ethanol solution serve as soft templates for hollow spherical silica (1-2 {mu}m). And if the emulsion is converted by the sol-gel process, one finds that suspended solid silica spheres of diameter of {approx}900 nm are formed. Moreover, several other factors are found to play fundamental roles in determining the final morphologies of silica particles, such as by variation of the pH (in our case, using OH{sup -}) to a level where condensation dominates; by changing the volume ratios of water/ethanol; and using an emulsifier (specifically, CTAB) - Graphical abstract: 'Local chemical etching' and sol-gel process have been proposed to interpret the control of morphologies of silica particles through varying initial pHs in syntheses. Highlights: Black-Right-Pointing-Pointer Different initial pHs in our syntheses provides morphological control of silica particles. Black-Right-Pointing-Pointer 'Local chemical etching' and sol-gel process describes the formation of silica spheres. Black-Right-Pointing-Pointer The formation of emulsions generates hollow silica particles.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

Molecular mechanism of 9-cis-retinoic acid inhibition of adipogenesis in 3T3-L1 cells

Highlights: ► We examined the effects of 9-cis-RA on adipogenesis in mouse preadipocyte 3T3-L1. ► 9-cis-RA inhibited lipid accumulation in adipogenetically-induced 3T3-L1 cells. ► A RXR pan-antagonist suppressed the inhibitory effects of 9-cis-RA on adipogenesis. ► This antagonist had no effects on RXRα and PPARγ levels in 9-cis-RA-treated cells. ► 9-cis-RA-induced decrease in both RXRα and PPARγ was independent of RXR activation. -- Abstract: Retinoic acid (RA) signaling is mediated by specific nuclear hormone receptors. Here we examined the effects of 9-cis-RA on adipogenesis in mouse preadipocyte 3T3-L1 cells. 9-cis-RA inhibits the lipid accumulation of adipogenetically induced 3T3-L1 cells. The complex of retinoid X receptor α (RXRα) with peroxisome proliferator-activated receptor γ (PPARγ) is a major transcription factor in the process of adipogenesis, and the levels of these molecules were decreased by 9-cis-RA treatment. A RXR pan-antagonist suppressed 9-cis-RA’s inhibitory effects on adipogenesis, but not on the intracellular levels of both RXRα and PPARγ. These results suggest that 9-cis-RA could inhibit adipogenesis by activating RXR, and decrease both RXR and PPARγs levels in a RXR activation-independent manner.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2024

Facile electrocatalytic proton reduction by a [Fe–Fe]-hydrogenase bio-inspired synthetic model bearing a terminal CN — ligand

An azadithiolate bridged CN — bound pentacarbonyl bis-iron complex, mimicking the active site of [Fe–Fe] H 2 ase is synthesized. The geometric and electronic structure of this complex is elucidated using a combination of EXAFS analysis, infrared and Mössbauer spectroscopy and DFT calculations. The electrochemical investigations show that complex 1 effectively reduces H + to H 2 between pH 0–3 at diffusion-controlled rates (10 11 M —1 s —1 ) i.e. 10 8 s —1 at pH 3 with an overpotential of 140 mV. Electrochemical analysis and DFT calculations suggests that a CN— ligand increases the p K a of the cluster enabling hydrogen production from its Fe(I)–Fe(0) state at pHs much higher and overpotential much lower than its precursor bis-iron hexacarbonyl model which is active in its Fe(0)–Fe(0) state. The formation of a terminal Fe–H species, evidenced by spectroelectrochemistry in organic solvent, via a rate determining proton coupled electron transfer step and protonation of the adjacent azadithiolate, lowers the kinetic barrier leading to diffusion controlled rates of H 2 evolution. The stereo-electronic factors enhance its catalytic rate by 3 order of magnitude relative to a bis-iron hexacarbonyl precursor at the same pH and potential.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Environmental limitation mapping of potential biomass resources across the conterminous U nited S tates

Abstract Several crops have recently been identified as potential dedicated bioenergy feedstocks for the production of power, fuels, and bioproducts. Despite being identified as early as the 1980s, no systematic work has been undertaken to characterize the spatial distribution of their long‐term production potentials in the United states. Such information is a starting point for planners and economic modelers, and there is a need for this spatial information to be developed in a consistent manner for a variety of crops, so that their production potentials can be intercompared to support crop selection decisions. As part of the Sun Grant Regional Feedstock Partnership (RFP), an approach to mapping these potential biomass resources was developed to take advantage of the informational synergy realized when bringing together coordinated field trials, close interaction with expert agronomists, and spatial modeling into a single, collaborative effort. A modeling and mapping system called PRISM‐ELM was designed to answer a basic question: How do climate and soil characteristics affect the spatial distribution and long‐term production patterns of a given crop? This empirical/mechanistic/biogeographical hybrid model employs a limiting factor approach, where productivity is determined by the most limiting of the factors addressed in submodels that simulate water balance, winter low‐temperature response, summer high‐temperature response, and soil pH , salinity, and drainage. Yield maps are developed through linear regressions relating soil and climate attributes to reported yield data. The model was parameterized and validated using grain yield data for winter wheat and maize, which served as benchmarks for parameterizing the model for upland and lowland switchgrass, CRP grasses, Miscanthus, biomass sorghum, energycane, willow, and poplar. The resulting maps served as potential production inputs to analyses comparing the viability of biomass crops under various economic scenarios. The modeling and parameterization framework can be expanded to include other biomass crops.

09 BIOMASS FUELS↗
DOE OSTI2012

Influence of electrolytes and membranes on cell operation for syn-gas production

The impact of membrane type and electrolyte composition for the electrochemical generation of synthesis gas (CO + H2) using a Ag gas diffusion electrode are presented. Changing from a cation exchange membrane to an anion exchange membrane (AEM) extended the cell operational time at low Ecell values (up to 4x) without impacting product composition. The use of KOH as the catholyte decreased the Ecell and resulted in a minimum electrolyte cost reduction of 39%. The prime factor in determining operational time at low Ecell values was the ability to maintain a sufficiently high anolyte pH.

10 SYNTHETIC FUELS↗
DOE OSTI2011

DEVELOPMENT OF AN APPROACH TO MODELING LOADING AND ELUTION OF SPHERICAL RESORCINOL FORMALDEHYDE ION-EXCHANGE RESIN

The current strategy for removal of cesium from the Hanford waste stream is ion-exchange using spherical Resorcinol-Formaldehyde (sRF) resin. The original resin of choice was granular SuperLig 644 resin and during testing of this resin several operational issues were identified. For example, the granular material had a high angle of internal friction resulting in fragmentation of resin particles along its edges during cycling and adverse hydraulic performance. Efforts to replace SuperLig 644 were undertaken and one candidate was the granular Resorcinol-Formaldehyde (RF) resin where experience with this cation exchanger dates back to the late 1940's. To minimize hydraulic concerns a spherical version of RF was developed and several different chemically produced batches were created. The 5E-370/641 batch of sRF was selected and for the last decade numerous studies have been performed (e.g., batch contact tests, column loading and elution tests). The Waste Treatment Plant (WTP) flowsheet shows that the aqueous phase waste stream will have a wide range of ionic concentrations (e.g., during the loading step 0-3 M free OH, 5+ M Na, 0-1 M K, 0-3 M NO{sub 3}). Several steps are required in the ion-exchange process to achieve the required Cs separation factors: loading, displacement, washing, elution, and regeneration. The sRF resin will be operated over a wide range in pH (i.e., pH of 12-14 during the loading step and pH of 0.01-1 during the elution step). During some of these steps very high levels of counter-ions and co-ions will be present within the aqueous phase. Alternative process feeds are under consideration as well (e.g., sodium levels as high as 8 M and column operation up to 45 C during loading, reduced and recycled HNO{sub 3} during elution). In order to model the performance of sRF resin through an entire ion-exchange cycle, a more robust isotherm model is required. To achieve this more robust isotherm model requires knowledge of the numbers and kinds of fixed ionogenic groups that make up sRF. Recent literature reviews and scoping titration tests strongly indicate that sRF is a polyfunctional cation exchange resin with at least three dominant types of ring groups playing a role in its isotherm behavior over the wide pH range of operations. Also three types of fixed ionogenic acid groups are present: sulfonic (SO{sub 3}H{sup -}) groups; carboxylic (COOH{sup -}) groups, and resorcylic (OH{sup -}) groups. It is this premise that we are working under in the development of a robust isotherm model for sRF over its entire planned pH operating range. The application of prototypic isotherms for modeling ion-exchange column behavior is demonstrated in Section 3 of this report. This preliminary work served to focus the development effort on the use of a mass-action based isotherm. In Section 4 of this report, the foundational material required to develop a robust isotherm model for sRF is provided. The paths taken, and choices made, are given for the reader to better understand our current status with respect to this goal and to highlight our most recent understanding of sRF exchange equilibria. Our ultimate goal is to update the CERMOD code (Aleman and Hamm, 2007) with a robust isotherm model for sRF that spans the entire pH and concentration ranges of planned operations. The isotherm model will then be used in the VERSE-LC code to model an entire ion-exchange cycle.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS1994

BATSE observations of 3C273

The quasar 3C273 has been detected by all instruments on CGRO. The emission from this source is monitored continuously by BATSE using Earth occultation. We present results of a preliminary analysis of BATSE data, including light curves of the 3C273 flux covering approximately 150 days in the interval April-August 1991 and approximately 350 days in the interval July 1992-April 1993. The source intensity in the energy range 50-300 keV is typically approx. 0.002 ph cm(exp -2)s(exp -1). We find weak evidence for variations of as much as a factor of 3 in the intensity. We derive spectral parameters of 3C273 during the intervals TJD 8422-8435 (15-28 June 1991) and TJD 8532-8546 (3-17 October 1991) for comparison with other CGRO instruments.

Paciesas, W.S.↗
DOE OSTI2015

Experiments and Modeling of Uranium Adsorption in the Presence of Other Ions in Simulated Seawater

Seawater contains uranium at an average concentration of 3.3 ppb, as well as a variety of other ions at either overwhelmingly higher or similar concentrations, which complicate the recovery of uranium. This report describes an investigation of the effects of various factors such as uranium speciation and presence of salts including sodium, calcium, magnesium, and bicarbonate, as well as trace elements such as vanadium on uranium adsorption kinetics in laboratory experiments. Adsorption models are also developed to describe the experimental data of uranium extraction from seawater. Results show that the presence of calcium and magnesium significantly slows down the uranium adsorption kinetics. Vanadium can replace uranium from amidoxime-based adsorbent in the presence of sodium in the solution. Results also show that bicarbonate in the solution strongly competes with amidoxime for binding uranium, and thus slows down the uranium adsorption kinetics. Developed on the basis of the experimental findings, the model is capable of describing the effects of pH, ionic strength, temperature, and concentration of various species. The results of this work are useful in the understanding of the important factors that control the adsorbent capacity and kinetics of uranium uptake by amidoxime-based adsorbents.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2025

Identification and overexpression of endogenous transcription factors to enhance lipid accumulation in the biotechnologically relevant species Chlamydomonas pacifica

Sustainable low-carbon energy solutions are critical to mitigating global carbon emissions. Algae-based platforms offer potential by converting carbon dioxide into valuable products while aiding carbon sequestration. However, scaling algae cultivation faces challenges like contamination in outdoor systems. Previously, our lab evolved Chlamydomonas pacifica, an extremophile green alga, which tolerates high temperature, pH, salinity, and light, making it ideal for large-scale bioproduct production, including biodiesel. Here, we enhanced lipid accumulation in evolved C. pacifica by identifying and overexpressing key endogenous transcription factors through genome-wide in-silico analysis and in-vivo testing. These factors include Lipid Remodeling Regulator 1 (CpaLRL1), Nitrogen Response Regulator 1 (CpaNRR1), Compromised Hydrolysis of Triacylglycerols 7 (CpaCHT7), and Phosphorus Starvation Response 1 (CpaPSR1). Under nitrogen deprivation, CpaLRL1, CpaNRR1, and CpaCHT7 overexpression enhanced lipid accumulation compared to wild-type. However, CpaPSR1 increased lipid accumulation compared to wild-type in normal media and did not increase further under nitrogen deprivation, highlighting the difference in function based on media conditions. Notably, lipid analysis of CpaPSR1 under normal media conditions revealed a 2.4-fold increase in triglycerides (TAGs) compared to the wild-type, highlighting its potential for biodiesel production. This approach provides a framework for transcription factor-focused metabolic engineering in algae, advancing bioenergy and biomaterial production.

Biofuels↗