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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

High-Temperature Controlled Redox Crystallization Studies

The crystallization of silicates containing redox sensitive ions (e.g., Fe, Ti, Ce) must be performed under controlled and known redox conditions in order to obtain the maximum scientific benefit from experimental study. Furthermore, many compositions crystallize dense phases which settle during ground-based experiments. This settling influences the texture and chemical evolution of the crystallizing system. The purpose of this investigation is to develop a test system in which controlled redox experiments can be performed in the microgravity environment. The system will use solid ceramic oxygen electrolyte cells for control, measurements, and production of the required redox conditions. A preliminary design for a prototype is developed, the electrolyte and furnace tested, and a tentative protocol for experiment developed. The control parameter is to be established and a laboratory prototype built.

Williams, R. J.↗
NASA NTRS1987

A system for conducting igneous petrology experiments under controlled redox conditions in reduced gravity

The Space Shuttle and the planned Space Station will permit experimentation under conditions of reduced gravitational acceleration offering experimental petrologists the opportunity to study crystal growth, element distribution, and phase chemistry. In particular the confounding effects of macro and micro scale buoyancy-induced convection and crystal settling or flotation can be greatly reduced over those observed in experiments in the terrestrial laboratory. Also, for experiments in which detailed replication of the environment is important, the access to reduced gravity will permit a more complete simulation of processes that may have occurred on asteroids or in free space. A technique that was developed to control, measure, and manipulate oxygen fugacities with small quantities of gas which are recirculated over the sample. This system could be adaptable to reduced gravity space experiments requiring redox control.

Williams, Richard J.↗
NASA NTRS1986

A system for conducting igneous petrology experiments under controlled redox conditions in reduced gravity

The Space Shuttle and the planned Space Station will permit experimentation under conditions of reduced gravitational acceleration offering experimental petrologists the opportunity to study crystal growth, element distribution, and phase chemistry. In particular the confounding effects of macro and micro scale buoyancy-induced convection and crystal settling or floatation can be greatly reduced over those observed in experiments in the terrestrial laboratory. Also, for experiments in which detailed replication of the environment is important, the access to reduced gravity will permit a more complete simulation of processes that may have occurred on asteroids or in free space. A technique that was developed to control, measure, and manipulate oxygen fugacites with small quantities of gas which are recirculated over the sample is described. This system should be adaptable to reduced gravity space experiments requiring redox control. Experiments done conventionally and those done using this technique yield identical results done in a 1-g field.

Williams, R. J.↗
NASA NTRS2003

Treatment of Spacecraft Wastewater Using a Hollow Fiber Membrane Biofilm Redox Control Reactor

The purpose of this project was to develop and evaluate design concepts for biological treatment reactors for the purification of spacecraft wastewater prior to reverse osmosis treatment. The motivating factor is that wastewater recovery represents the greatest single potential reduction in the resupply requirements for crewed space missions. Spacecraft wastewater composition was estimated from the characteristics of the three major component streams: urine/flush water, hygiene water, and atmospheric condensate. The key characteristics of composite spacecraft wastewater are a theoretical oxygen demand of 4519 mg/L, of which 65% is nitrogenous oxygen demand, in a volume of 11.5 liter/crew-day. The organic carbon to nitrogen ratio of composite wastewater is 0.86. Urine represents 93% of nitrogen and 49% of the organic carbon in the composite wastestream. Various bioreaction scenarios were evaluated to project stoichiometric oxygen demands and the ability of wastewater carbon to support denitrification. Ammonia nitrification to the nitrite oxidation state reduced the oxygen requirement and enabled wastewater carbon to provide nearly complete denitrification. A conceptual bioreactor design was established using hollow fiber membranes for bubbleless oxygen transfer in a gravity-free environment, in close spatial juxtaposition to a second interspaced hollow fiber array for supplying molecular hydrogen. Highly versatile redox control and an enhanced ability to engineer syntrophic associations are stated advantages. A prototype reactor was constructed using a microporous hollow fiber membrane module for aeration. Maintaining inlet gas pressure within 0.25 psi of the external water pressure resulted in bubble free operation with no water ingress into hollow fiber lumens. Recommendations include the design and operational testing of hollow fiber bioreactors using: 1) Partial nitrification/nitrite predenitrification; 2) Limited aeration for simultaneous nitrification/denitrification or for nitrite reduction/ammonia oxidation; 3) Hydrogenotrophic denitrification.

Smith, Daniel P.↗
NASA NTRS1993

Technical Update: Johnson Space Center system using a solid electrolytic cell in a remote location to measure oxygen fugacities in CO/CO2 controlled-atmosphere furnaces

Details are given for the design and application of a (one atmosphere) redox-control system. This system differs from that given in NASA Technical Memorandum 58234 in that it uses a single solid-electrolytic cell in a remote location to measure the oxygen fugacities of multiple CO/CO2 controlled-atmosphere furnaces. This remote measurement extends the range of sample-furnace conditions that can be measured using a solid-electrolytic cell, and cuts costs by extending the life of the sensors and by minimizing the number of sensors in use. The system consists of a reference furnace and an exhaust-gas manifold. The reference furnace is designed according to the redox control system of NASA Technical Memorandum 58234, and any number of CO/CO2 controlled-atmosphere furnaces can be attached to the exhaust-gas manifold. Using the manifold, the exhaust gas from individual CO/CO2 controlled atmosphere furnaces can be diverted through the reference furnace, where a solid-electrolyte cell is used to read the ambient oxygen fugacity. The oxygen fugacity measured in the reference furnace can then be used to calculate the oxygen fugacity in the individual CO/CO2 controlled-atmosphere furnace. A BASIC computer program was developed to expedite this calculation.

Jurewicz, A. J. G.↗
NASA NTRS1981

JSC systems using solid ceramic oxygen electrolyte cells to measure oxygen fugacites in gas-mixing systems

Details are given for the construction and operation of a 101.3 KN/sq meter (1 atmosphere) redox control system. A solid ceramic oxygen electrolyte cell is used to monitor the oxygen fugacity in the furnace. The system consists of a vertical quench gas mixing furnace with heads designed for mounting the electrolyte cell and with facilities for inserting and removing the samples, a simplified version of a gas mixing apparatus, and devices for experiments under controlled rates of change of temperature. A thermogravimetric analysis system employing these techniques of redox control and measurement is also described. The calibration and maintenance of the system are discussed.

Williams, R. J.↗
NASA NTRS1976

A system using solid ceramic oxygen electrolyte cells to measure oxygen fugacities in gas-mixing systems

Details are given for the construction and operation of a 101.3 kN/sq m (1 atmosphere) redox control system. A solid ceramic oxygen electrolyte cell is used to monitor the oxygen fugacity in the furnace. The system consists of a vertical quench, gas mixing furnace with heads designed for mounting the electrolyte cell and with facilities for inserting and removing the samples. The system also contains the high input impedance electronics necessary for measurements, a simplified version of a gas mixing apparatus, and devices for experiments under controlled rates of change relative to temperature and redox state. The calibration and maintenance of the system are discussed.

Williams, R. J.↗
NASA NTRS2005

Metabolic Reactions among Organic Sulfur Compounds

Sulfur is central to the metabolisms of many organisms that inhabit extreme environments. Numerous authors have addressed the energy available from a variety of inorganic sulfur redox pairs. Less attention has been paid, however, to the energy required or gained from metabolic reactions among organic sulfur compounds. Work in this area has focused on the oxidation of alkyl sulfide or disulfide to thiol and formaldehyde, e.g. (CH3)2S + H2O yields CH3SH + HCHO + H2, eventually resulting in the formation of CO2 and SO4(-2). It is also found that reactions among thiols and disulfides may help control redox disequilibria between the cytoplasm and the periplasm. Building on our earlier efforts for thiols, we have compiled and estimated thermodynamic properties for alkyl sulfides. We are investigating metabolic reactions among various sulfur compounds in a variety of extreme environments, ranging from sea floor hydrothermal systems to organic-rich sludge. Using thermodynamic data and the revised HKF equation of state, along with constraints imposed by the geochemical environments sulfur-metabolizing organisms inhabit, we are able to calculate the amount of energy available to these organisms.

Schulte, M.↗
NASA NTRS1977

Electrolyte cells measure oxygen fugacities

System that uses calcia-stabilized zirconia-ceramic electrolyte in oxygen concentration cell can directly measure oxygen fugacity in vertical-quench furnace, redox-control system. System can independently vary temperature and oxygen fugacity during experiments, and can record these parameters as function of time.

Williams, R. J.↗
NASA NTRS2010

Trace Element Compositions of Pallasite Olivine Grains and Pallasite Origin

Pallasites are mixtures of metal with magnesian olivine. Most have similar metal compositions and olivine oxygen isotopic compositions; these are the main-group pallasites (PMG). The Eagle Station grouplet of pallasites (PES) have distinctive metal and olivine compositions and oxygen isotopic compositions. Pallasites are thought to have formed at the core-mantle boundary of their parent asteroids by mixing molten metal with solid olivine of either cumulatic or restitic origin. We have continued our investigation of pallasite olivines by doing in situ trace element analyses in order to further constrain their origin. We determined Al, P, Ca, Ga and first row transition element contents of olivine grains from suite of PMG and PES by LA-ICP-MS at JSC. Included in the PMG suite are some that have anomalous metal compositions (PMG-am) and atypically ferroan olivines (PMG-as). Our EMPA work has shown that there are unanticipated variations in olivine Fe/Mn, even within those PMG that have uni-form Fe/Mg. Manganese is homologous with Fe2+, and thus can be used the same way to investigate magmatic fractionation processes. It has an advantage for pallasite studies in that it is unaffected by redox exchange with the metal. PMG can be divided into three clusters on the basis of Mn/Mg; low, medium and high that can be thought of as less, typically and more fractionated in an igneous sense. The majority of PMG have medium Mn/Mg ratios. PMG-am occur in all three clusters; there does not seem to be any relationship between putative olivine igneous fractionation and metal composition. The PMG-as and one PMG-am make up the high Mn/Mg cluster; no PMG are in this cluster. The high Mn/Mg cluster ought to be the most fractionated (equivalent to the most Fe-rich in igneous suites), yet they have among the lowest contents of incompatible lithophile elements Al and Ti and the two PMG-as in this cluster also have low Ca and Sc contents. This is inconsistent with simple igneous fractionation on a single, initially homogeneous parent asteroid. For Al and Ti, the low and high Mn/Mg clusters have generally uniform contents, while the medium cluster has wide ranges. This is also true of analyses of duplicate grains from the medium cluster pallasites which can have very different Al and Ti contents. Those from the low and high clusters do not. These observations suggest that pallasite olivines are not cumulates, but rather are restites from high degrees of melting. The moderately siderophile elements P and Ga show wide ranges in the high Mn/Mg cluster, but very uniform compositions in the medium cluster, opposite the case for Al and Ti. There is no correlation of P or Ga and Fe/Mn as might be expected if redox processes controlled the contents of moderately siderophile elements in the olivines. The lack of correlation of P could reflect equilibration with phosphates, although there is no correlation of Ca with P as might be expected

Mittlefehldt, David W.↗
NASA NTRS2023

Natural sunlight-driven oxidation of Mn 2+ (aq) and heterogeneous formation of Mn oxides on hematite

The oxidation of dissolved Mn 2+ (aq) plays a critical role in driving manganese cycles and regulating the fate of essential elements and contaminants in environmental systems. Based on sluggish oxidation rate, abiotic processes have been considered less effective oxidation pathway for manganese oxidation in environmental systems. Interestingly, a recent study (Jung et al., 2021) has shown that the rapid photochemical oxidation of Mn 2+ (aq) could be a feasible scenario to uncover the potential significance of abiotic Mn 2+ (aq) oxidation. Nevertheless, the significance of photochemical oxidation of Mn 2+ (aq) under natural sunlight exposure remains unclear. Here, we demonstrate the rapid photocatalytic oxidation of Mn 2+ (aq) and the heterogeneous growth of tunnel-structured Mn oxides under simulated freshwater and seawater conditions in the presence of natural sunlight and hematite. The natural sunlight-driven photocatalytic oxidation of Mn 2+ (aq) by hematite showed kinetic constants of 1.02 h -−1 and 0.342 h −1 under freshwater and seawater conditions, respectively. The natural sunlight-driven photocatalytic oxidation rates are quite comparable to the results obtained from the previous laboratory test using artificial sunlight, which has ∼4.5 times stronger light intensity. It is likely because of ∼5.5 times larger light exposure area in the natural sunlight-driven photocatalytic oxidation than that of the laboratory test using artificial sunlight. We also elucidate the roles of cation species in controlling the oxidation rate of Mn 2+ (aq) and the crystalline structure of Mn oxide products. Specifically, in the presence of large amounts of cations, the oxidation rate of Mn 2+ (aq) was slower likely because of competitive adsorption. Furthermore, our findings highlight that Mn 2+ contributes significantly to the formation of large-tunneled Mn oxides. These results illuminate the importance of abiotic photocatalytic processes in controlling the redox chemistry of Mn in real environmental aqueous systems on the oxidation of Mn 2+ (aq), and provide an environmentally sustainable approach to effectively remediate water contaminated with Mn 2+ (aq) using natural sunlight.

Junyeong Choi↗
NASA NTRS1974

Passivation of pigment particles for thermal control coatings

Various redox couple surface additives are studied which increase the photostability of coprecipitated zinc orthotitanate pigment. The electron spin resonance technique was used to examine the characteristic photodamage centers. Results indicate that cerium surface redox additive completely passivates the pigment at the surface concentrations studied. Less passivation occurs with the iridium chloride and the iron cyanide redox couples.

Sancier, K. M.↗
NASA NTRSDate not supplied

Metal-silicate Partitioning of Re, Ru, Pt, Os, Ti, Nb, and Ta in Reduced Differentiated Planetary Bodies

Siderophile (iron-loving) elements are strongly fractionated during differentiation of planetary bodies into core and mantle [1]. Because the fractionation is controlled by the pressure, temperature, redox conditions, and composition, this group of elements can provide important constraints on the conditions of accretion and core formation in early solar system bodies (planetesimals) and planets (Earth, Mercury, Venus)[2]. At the reducing conditions thought to prevail in the early solar system, Si is known to alloy with FeNi metallic liquids (e.g., [3]) affecting the activity coefficients of siderophile elements in FeNi liquids and thus ultimately their detailed partitioning between metal and silicate melt. The effect of Si can be significant for some siderophile elements, as demonstrated previously by (e.g., [4]: Ni, Co; [5,6]: Ge, As, Sb, Pd, Pt, Au). The effect of Si has not yet been determined for several key groups of siderophile elements including the highly siderophile Re, Ru and Os, and the weakly siderophile Ta, Nb, and Ti. Here, we report new experiments designed to quantify the effect of Si on the partitioning of Re, Pt, Os, Ru, Ti, Ta and Nb between metal and silicate melts. The results will be used to evaluate metal/silicate equilibrium for Nb, Ta, Ti and Nb/Ta ratios in planetary mantles, mantle concentrations of Ru, Re, Pt, Os during accretion, the evolution of Re/Os, Pt/Os ratios in magma oceans, and the role of late veneer in establishing Re and Ru abundances in the terrestrial mantle.

core formation↗
NASA NTRS2009

Selective functionalization of carbon nanotube tips allowing fabrication of new classes of nanoscale sensing and manipulation tools

Embodiments in accordance with the present invention relate to techniques for the growth and attachment of single wall carbon nanotubes (SWNT), facilitating their use as robust and well-characterized tools for AFM imaging and other applications. In accordance with one embodiment, SWNTs attached to an AFM tip can function as a structural scaffold for nanoscale device fabrication on a scanning probe. Such a probe can trigger, with nanometer precision, specific biochemical reactions or conformational changes in biological systems. The consequences of such triggering can be observed in real time by single-molecule fluorescence, electrical, and/or AFM sensing. Specific embodiments in accordance with the present invention utilize sensing and manipulation of individual molecules with carbon nanotubes, coupled with single-molecule fluorescence imaging, to allow observation of spectroscopic signals in response to mechanically induced molecular changes. Biological macromolecules such as proteins or DNA can be attached to nanotubes to create highly specific single-molecule probes for investigations of intermolecular dynamics, for assembling hybrid biological and nanoscale materials, or for developing molecular electronics. In one example, electrical wiring of single redox enzymes to carbon nanotube scanning probes allows observation and electrochemical control over single enzymatic reactions by monitoring fluorescence from a redox-active cofactor or the formation of fluorescent products. Enzymes ''nanowired'' to the tips of carbon nanotubes in accordance with embodiments of the present invention, may enable extremely sensitive probing of biological stimulus-response with high spatial resolution, including product-induced signal transduction.

Wade, Lawrence A.↗
NASA NTRS2015

Flexible Hybrid Battery/Pseudocapacitor

Batteries keep devices working by utilizing high energy density, however, they can run down and take tens of minutes to hours to recharge. For rapid power delivery and recharging, high-power density devices, i.e., supercapacitors, are used. The electrochemical processes which occur in batteries and supercapacitors give rise to different charge-storage properties. In lithium ion (Li+) batteries, the insertion of Li+, which enables redox reactions in bulk electrode materials, is diffusion controlled and can be slow. Supercapacitor devices, also known as electrical double-layer capacitors (EDLCs) store charge by adsorption of electrolyte ions onto the surface of electrode materials. No redox reactions are necessary, so the response to changes in potential without diffusion limitations is rapid and leads to high power. However, the charge in EDLCs is confined to the surface, so the energy density is lower than that of batteries.

Tucker, Dennis S.↗
NASA NTRS2013

The W-W02 Oxygen Fugacity Buffer at High Pressures and Temperatures: Implications for f02 Buffering and Metal-silicate Partitioning

Oxygen fugacity (fO2) controls multivalent phase equilibria and partitioning of redox-sensitive elements, and it is important to understand this thermodynamic parameter in experimental and natural systems. The coexistence of a metal and its oxide at equilibrium constitutes an oxygen buffer which can be used to control or calculate fO2 in high pressure experiments. Application of 1-bar buffers to high pressure conditions can lead to inaccuracies in fO2 calculations because of unconstrained pressure dependencies. Extending fO2 buffers to pressures and temperatures corresponding to the Earth's deep interior requires precise determinations of the difference in volume (Delta) V) between the buffer phases. Synchrotron x-ray diffraction data were obtained using diamond anvil cells (DAC) and a multi anvil press (MAP) to measure unit cell volumes of W and WO2 at pressures and temperatures up to 70 GPa and 2300 K. These data were fitted to Birch-Murnaghan 3rd-order thermal equations of state using a thermal pressure approach; parameters for W are KT = 306 GPa, KT' = 4.06, and αKT = 0.00417 GPa K-1. Two structural phase transitions were observed for WO2 at 4 and 32 GPa with structures in P21/c, Pnma and C2/c space groups. Equations of state were fitted for these phases over their respective pressure ranges yielding the parameters KT = 190, 213, 300 GPa, KT' = 4.24, 5.17, 4 (fixed), and αKT = 0.00506, 0.00419, 0.00467 GPa K-1 for the P21/c, Pnma and C2/c phases, respectively. The W-WO2 buffer (WWO) was extended to high pressure by inverting the W and WO2 equations of state to obtain phase volumes at discrete pressures (1-bar to 100 GPa, 1 GPa increments) along isotherms (300 to 3000K, 100 K increments). The slope of the absolute fO2 of the WWO buffer is positive with increasing temperature up to approximately 70 GPa and is negative above this pressure. The slope is positive along isotherms from 1000 to 3000K with increasing pressure up to at least 100 GPa. The WWO buffer is at a higher fO2 than the IW buffer at pressures lower than 40 GPa, and the magnitude of this difference decreases at higher pressures. This qualitatively indicates an increasingly lithophile character for W at higher pressures. The WWO buffer was quantitatively applied to W metal-silicate partitioning by using the WWO-IW buffer difference in combination with literature data on W metal-silicate partitioning to model the exchange coefficient (KD) for the Fe-W exchange reaction. This approach captures the pressure dependence of W metal-silicate partitioning using the WWO-IW buffer difference and models the activities of the components in the silicate and metallic phases using an expression of the Gibbs excess energy of mixing. Calculation of KD along a peridotite liquidus predicts a decrease in W siderophility at higher pressures that supports the qualitative behavior predicted by the WWO-IW buffer difference, and agrees with findings of others. Comparing the competing effects of temperature and pressure on W metal-silicate partitioning, our results indicate that pressure exerts a greater effect.

Shofner, G. A.↗
NASA NTRS1993

The mechanosensory calcium-selective ion channel: key component of a plasmalemmal control centre?

Mechanosensory calcium-selective ion channels probably serve to detect not only mechanical stress but also electrical, thermal, and diverse chemical stimuli. Because all stimuli result in a common output, most notably a shift in second messenger calcium concentration, the channels are presumed to serve as signal integrators. Further, insofar as second messenger calcium in turn gives rise to mechanical, electrical, and diverse chemical changes, the channels are postulated to initiate regulatory feedbacks. It is proposed that the channels and the feedback loops play a wide range of roles in regulating normal plant function, as well as in mediating disturbance of normal function by environmental stressors and various pathogens. In developing evidence for the physiological performance of the channel, a model for a cluster of regulatory plasmalemmal proteins and cytoskeletal elements grouped around a set of wall-to-membrane and transmembrane linkers has proved useful. An illustration of how the model might operate is presented. It is founded on the demonstration that several xenobiotics interfere both with normal channel behaviour and with gravitropic reception. Accordingly, the first part of the illustration deals with how the channels and the control system within which they putatively operate might initiate gravitropism. Assuming that gravitropism is an asymmetric expression of growth, the activities of the channels and the plasmalemmal control system are extrapolated to account for regulation of both rate and allometry of cell expansion. Finally, it is discussed how light, hormones, redox agents and herbicides could in principle affect growth via the putative plasmalemmal control cluster or centre.

NASA Program Space Biology↗
NASA NTRS1991

Biologically controlled minerals as potential indicators of life

Minerals can be produced and deposited either by abiotic or biologic means. Regardless of their origin, mineral crystals reflect the environment conditions (e.g., temperature, pressure, chemical composition, and redox potential) present during crystal formation. Biologically-produced mineral crystals are grown or reworked under the control of their host organism and reflect an environment different from the abiotic environment. In addition, minerals of either biologic or abiotic origin have great longevities. For these reasons, biologically produced minerals have been proposed as biomarkers. Biomarkers are key morphological, chemical, and isotopic signatures of living systems that can be used to determine if life processes have occurred. Studies of biologically controlled minerals produced by the protist, Paramecium tetraurelia, were initiated since techniques have already been developed to culture them and isolate their crystalline material, and methods are already in place to analyze this material. Two direct crystalline phases were identified. One phase, whose chemical composition is high in Mg, was identified as struvite. The second phase, whose chemical composition is high in Ca, has not been previously found occurring naturally and may be considered a newly discovered material. Analyses are underway to determine the characteristics of these minerals in order to compare them with characteristics of these minerals in order to compare them with characteristics of minerals formed abiotically, but with the same chemical composition.

Schwartz, D. E.↗