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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1971

The polymorphic and mesomorphic behavior of four esters of cholesterol.

The techniques of differential scanning calorimetry, X-ray powder diffractometry, and positron annihilation have been used to study the polymorphic and mesomorphic behavior of the following esters of cholesterol: cholesteryl formate, cholesteryl butyrate, cholesteryl benzoate, and cholesteryl cinnamate. Each of these compounds exhibits a single mesophase of the cholesteric type. The solid phase formed from the melt for each ester was observed to be structurally different from the solid phase obtained from solution. Solvents from which the solution-grown samples were crystallized were as follows: cholesteryl formate and cholesteryl butyrate from acetone, cholesteryl benzoate from benzene, and cholesteryl cinnamate from 2-butanone.

Merritt, W. G.↗
NASA NTRS1985

Production of butanol by fermentation in the presence of cocultures of clostridium

Sugars are converted to a mixture of solvents including butanol by a fermentation process employing a coculture of microorganisms of the Clostridium genus, one of said microorganisms favoring the production of butyric acid and the other of which converts the butyric acid so produced to butanol. The use of a coculture substantially increases the yield of butanol over that obtained using a culture employing only one microorganism.

Bergstrom, S. L.↗
NASA NTRS2000

Halogenated auxins affect microtubules and root elongation in Lactuca sativa

We studied the effect of 4,4,4-trifluoro-3-(indole-3-)butyric acid (TFIBA), a recently described root growth stimulator, and 5,6-dichloro-indole-3-acetic acid (DCIAA) on growth and microtubule (MT) organization in roots of Lactuca sativa L. DCIAA and indole-3-butyric acid (IBA) inhibited root elongation and depolymerized MTs in the cortex of the elongation zone, inhibited the elongation of stele cells, and promoted xylem maturation. Both auxins caused the plane of cell division to shift from anticlinal to periclinal. In contrast, TFIBA (100 micromolar) promoted elongation of primary roots by 40% and stimulated the elongation of lateral roots, even in the presence of IBA, the microtubular inhibitors oryzalin and taxol, or the auxin transport inhibitor naphthylphthalamic acid. However, TFIBA inhibited the formation of lateral root primordia. Immunostaining showed that TFIBA stabilized MTs orientation perpendicular to the root axis, doubled the cortical cell length, but delayed xylem maturation. The data indicate that the auxin-induced inhibition of elongation and swelling of roots results from reoriented phragmoplasts, the destabilization of MTs in elongating cells, and promotion of vessel formation. In contrast, TFIBA induced promotion of root elongation by enhancing cell length, prolonging transverse MT orientation, delaying cell and xylem maturation.

Non-NASA Center↗
NASA NTRS1999

Syntrophus aciditrophicus sp. nov., a new anaerobic bacterium that degrades fatty acids and benzoate in syntrophic association with hydrogen-using microorganisms

Strain SBT is a new, strictly anaerobic, gram-negative, nonmotile, non-sporeforming, rod-shaped bacterium that degrades benzoate and certain fatty acids in syntrophic association with hydrogen/formate-using microorganisms. Strain SBT produced approximately 3 mol of acetate and 0.6 mol of methane per mol of benzoate in coculture with Methanospirillum hungatei strain JF1. Saturated fatty acids, some unsaturated fatty acids, and methyl esters of butyrate and hexanoate also supported growth of strain SBT in coculture with Desulfovibrio strain G11. Strain SBT grew in pure culture with crotonate, producing acetate, butyrate, caproate, and hydrogen. The molar growth yield was 17 +/- 1 g cell dry mass per mol of crotonate. Strain SBT did not grow with fumarate, iron(III), polysulfide, or oxyanions of sulfur or nitrogen as electron acceptors with benzoate as the electron donor. The DNA base composition of strain SBT was 43.1 mol% G+C. Analysis of the 16 S rRNA gene sequence placed strain SBT in the delta-subdivision of the Proteobacteria, with sulfate-reducing bacteria. Strain SBT was most closely related to members of the genus Syntrophus. The clear phenotypic and genotypic differences between strain SBT and the two described species in the genus Syntrophus justify the formation of a new species, Syntrophus aciditrophicus.

Non-NASA Center↗
NASA NTRS1997

Enantiomeric excesses in meteoritic amino acids

Gas chromatographic-mass spectral analyses of the four stereoisomers of 2-amino-2,3-dimethylpentanoic acid (dl-alpha-methylisoleucine and dl-alpha-methylalloisoleucine) obtained from the Murchison meteorite show that the L enantiomer occurs in excess (7.0 and 9.1%, respectively) in both of the enantiomeric pairs. Similar results were obtained for two other alpha-methyl amino acids, isovaline and alpha-methylnorvaline, although the alpha hydrogen analogs of these amino acids, alpha-amino-n-butyric acid and norvaline, were found to be racemates. With the exception of alpha-amino-n-butyric acid, these amino acids are either unknown or of limited occurrence in the biosphere. Because carbonaceous chondrites formed 4.5 billion years ago, the results are indicative of an asymmetric influence on organic chemical evolution before the origin of life.

NASA Program Exobiology↗
NASA NTRS2008

Optimized Carbonate and Ester-Based Li-Ion Electrolytes

To maintain high conductivity in low temperatures, electrolyte co-solvents have been designed to have a high dielectric constant, low viscosity, adequate coordination behavior, and appropriate liquid ranges and salt solubilities. Electrolytes that contain ester-based co-solvents in large proportion (greater than 50 percent) and ethylene carbonate (EC) in small proportion (less than 20 percent) improve low-temperature performance in MCMB carbon-LiNiCoO2 lithium-ion cells. These co-solvents have been demonstrated to enhance performance, especially at temperatures down to 70 C. Low-viscosity, ester-based co-solvents were incorporated into multi-component electrolytes of the following composition: 1.0 M LiPF6 in ethylene carbonate (EC) + ethyl methyl carbonate (EMC) + X (1:1:8 volume percent) [where X = methyl butyrate (MB), ethyl butyrate EB, methyl propionate (MP), or ethyl valerate (EV)]. These electrolyte formulations result in improved low-temperature performance of lithium-ion cells, with dramatic results at temperatures below 40 C.

Smart, Marshall↗
NASA NTRS2005

Ester-Based Electrolytes for Low-Temperature Li-Ion Cells

Electrolytes comprising LiPF6 dissolved at a concentration of 1.0 M in five different solvent mixtures of alkyl carbonates have been found to afford improved performance in rechargeable lithium-ion electrochemical cells at temperatures as low as -70 C. These and other electrolytes have been investigated in continuing research directed toward extending the lower limit of practical operating temperatures of Li-ion cells. This research at earlier stages, and the underlying physical and chemical principles, were reported in numerous previous NASA Tech Briefs articles, the most recent being Low-EC-Content Electrolytes for Low-Temperature Li-Ion Cells (NPO-30226), NASA Tech Briefs, Vol. 27, No. 1 (January 2003), page 46. The ingredients of the present solvent mixtures are ethylene carbonate (EC), ethyl methyl carbonate (EMC), methyl butyrate (MB), methyl propionate (MP), ethyl propionate (EP), ethyl butyrate (EB), and ethyl valerate (EV). In terms of volume proportions of these ingredients, the present solvent mixtures are 1EC + 1EMC + 8MB, 1EC + 1EMC + 8EB, 1EC + 1EMC + 8MP, 1EC + 1EMC + 8EV, and 1EC + 9EMC. These electrolytes were placed in Liion cells containing carbon anodes and LiNi0.8Co0.2O2 cathodes, and the low-temperature electrical performances of the cells were measured. The cells containing the MB and MP mixtures performed best.

Smart, Marshall↗
NASA NTRS2011

NASA Tech Briefs, October 2011

Topics covered include: Laser Truss Sensor for Segmented Telescope Phasing; Qualifications of Bonding Process of Temperature Sensors to Deep-Space Missions; Optical Sensors for Monitoring Gamma and Neutron Radiation; Compliant Tactile Sensors; Cytometer on a Chip; Measuring Input Thresholds on an Existing Board; Scanning and Defocusing Properties of Microstrip Reflectarray Antennas; Cable Tester Box; Programmable Oscillator; Fault-Tolerant, Radiation-Hard DSP; Sub-Shot Noise Power Source for Microelectronics; Asynchronous Message Service Reference Implementation; Zero-Copy Objects System; Delay and Disruption Tolerant Networking MACHETE Model; Contact Graph Routing; Parallel Eclipse Project Checkout; Technique for Configuring an Actively Cooled Thermal Shield in a Flight System; Use of Additives to Improve Performance of Methyl Butyrate-Based Lithium-Ion Electrolytes; Li-Ion Cells Employing Electrolytes with Methyl Propionate and Ethyl Butyrate Co-Solvents; Improved Devices for Collecting Sweat for Chemical Analysis; Tissue Photolithography; Method for Impeding Degradation of Porous Silicon Structures; External Cooling Coupled to Reduced Extremity Pressure Device; A Zero-Gravity Cup for Drinking Beverages in Microgravity; Co-Flow Hollow Cathode Technology; Programmable Aperture with MEMS Microshutter Arrays; Polished Panel Optical Receiver for Simultaneous RF/Optical Telemetry with Large DSN Antennas; Adaptive System Modeling for Spacecraft Simulation; Lidar-Based Navigation Algorithm for Safe Lunar Landing; Tracking Object Existence From an Autonomous Patrol Vehicle; Rad-Hard, Miniaturized, Scalable, High-Voltage Switching Module for Power Applications; and Architecture for a 1-GHz Digital RADAR.

Source record↗
NASA NTRS2012

Lithium Batteries and Supercapacitors Capable of Operating at Low Temperatures for Planetary Exploration

Demonstrated improved performance with wide operating temperature electrolytes containing ester co - solvents (i.e., methyl propionate and ethyl butyrate) in a number of prototype cells: center dot Successfully scaled up low temperature technology to 12 Ah size prismatic Li - ion cells (Quallion, LCC), and demonstrated good performance down to - 60 o C. center dot Demonstrated wide operating temperature range performance ( - 60 o to +60 o C) in A123 Systems LiFePO 4 - based lithium - ion cells containing methyl butyrate - based low temperature electrolytes. These systems were also demonstrated to have excellent cycle life performance at ambient temperatures, as well as the ability to be cycled up to high temperatures.

Li-ion Batteries↗
NASA NTRS2012

Wide Operating Temperature Range Electrolytes for High Voltage and High Specific Energy Li-Ion Cells

A number of electrolyte formulations that have been designed to operate over a wide temperature range have been investigated in conjunction with layered-layered metal oxide cathode materials developed at Argonne. In this study, we have evaluated a number of electrolytes in Li-ion cells consisting of Conoco Phillips A12 graphite anodes and Toda HE5050 Li(1.2)Ni(0.15)Co(0.10)Mn(0.55)O2 cathodes. The electrolytes studied consisted of LiPF6 in carbonate-based electrolytes that contain ester co-solvents with various solid electrolyte interphase (SEI) promoting additives, many of which have been demonstrated to perform well in 4V systems. More specifically, we have investigated the performance of a number of methyl butyrate (MB) containing electrolytes (i.e., LiPF6 in ethylene carbonate (EC) + ethyl methyl carbonate (EMC) + MB (20:20:60 v/v %) that contain various additives, including vinylene carbonate, lithium oxalate, and lithium bis(oxalato)borate (LiBOB). When these systems were evaluated at various rates at low temperatures, the methyl butyrate-based electrolytes resulted in improved rate capability compared to cells with all carbonate-based formulations. It was also ascertained that the slow cathode kinetics govern the generally poor rate capability at low temperature in contrast to traditionally used LiNi(0.80)Co(0.15)Al(0.05)O2-based systems, rather than being influenced strongly by the electrolyte type.

Li-ion Battery↗
NASA NTRS1977

Formation of fatty acids in photochemical conversions of saturated hydrocarbons

Abiogenic synthesis of fatty acids was studied in photochemical conversions of saturated hydrocarbons. It was shown that, in a hydrocarbon water CaCO3 suspension, the action of 254 nm UV rays caused the formation of fatty acids with a maximum number of carbon atoms in the chain not exceeding that in the initial hydrocarbon. Synthesis of acetic, propionic, butyric, valeric, caproic, enanthic and caprylic (in the case of octane) acids occurs in heptane water CaCO3 and octane water CaCO3 systems.

Telegina, T. A.↗
NASA NTRS1979

Development and Testing of Shingle-type Solar Cell Modules

The design, development, fabrication and testing of a shingle-type terrestrial solar cell module which produces 98 watts/sq m of exposed module area at 1 kW/sq m insolation and 61 C are reported. These modules make it possible to easily incorporate photovoltaic power generation into the sloping roofs of residential or commercial buildings by simply nailing the modules to the plywood roof sheathing. This design consists of nineteen series-connected 53 mm diameter solar cells arranged in a closely packed hexagon configuration. These cells are individually bonded to the embossed surface of a 3 mm thick thermally tempered hexagon-shaped piece of glass. Polyvinyl butyral is used as the laminating adhesive.

Shepard, N. F., Jr.↗
NASA NTRS1980

A conceptual design study of a high temperature solar thermal receiver (added tasks 6 and 7)

The key component of this concept is a coiled tube of silicon nitride which acts as a heat exchanger appears to be ideal from the standpoint of utilizing structural ceramics at around 2500 F under severe thermal shock conditions. However the size and configuration of this coil are beyond the state of the art for fabricating such materials as silicon nitride and carbide. A two-task program to develop and demonstrate the feasibility of extruding and forming a section of thin walled silicon nitride tubing was undertaken as an addition to the original program. A promising polyvinyl butyral-based binder lubricant was identified. Fourteen full size extrusion experiments were conducted. Two trial firings of 1-1/4 turn helices were made.

Robertson, C. S.↗
NASA NTRS1981

Reasons for the occurrence of the twenty coded protein amino acids

Factors involved in the selection of the 20 protein L-alpha-amino acids during chemical evolution and the early stages of Darwinian evolution are discussed. The selection is considered on the basis of the availability in the primitive ocean, function in proteins, the stability of the amino acid and its peptides, stability to racemization, and stability on the transfer RNA. It is concluded that aspartic acid, glutamic acid, arginine, lysine, serine and possibly threonine are the best choices for acidic, basic and hydroxy amino acids. The hydrophobic amino acids are reasonable choices, except for the puzzling absences of alpha-amino-n-butyric acid, norvaline and norleucine. The choices of the sulfur and aromatic amino acids seem reasonable, but are not compelling. Asparagine and glutamine are apparently not primitive. If life were to arise on another planet, it would be expected that the catalysts would be poly-alpha-amino acids and that about 75% of the amino acids would be the same as on the earth.

Weber, A. L.↗
NASA NTRS1984

The spark discharge synthesis of amino acids from various hydrocarbons

The spark discharge synthesis of amino acids using an atmosphere of CH4+N2+H2O+NH3 has been investigated with variable pNH3. The amino acids produced using higher hydrocarbons (ethane, ethylene, acetylene, propane, butane, and isobutane) instead of CH4 were also investigated. There was considerable range in the absolute yields of amino acids, but the yields relative to glycine (or alpha-amino-n-butyric acid) were more uniform. The relative yields of the C3 to C6 aliphatic alpha-amino acids are nearly the same (with a few exceptions) with all the hydrocarbons. The glycine yields are more variable. The precursors to the C3-C6 aliphatic amino acids seem to be produced in the same process, which is separate from the synthesis of glycine precursors. It may be possible to use these relative yields as a signature for a spark discharge synthesis provided corrections can be made for subsequent decomposition events (e.g. in the Murchison meteorite).

Ring, D.↗
NASA NTRS1983

Assessing photovoltaic module degradation and lifetime from long term environmental tests

The photovoltaic module failure mechanisms related to temperature, humidity, and electrical bias are analyzed using the data collected over a period of 20 years from various sites in the U.S. The approach is based on measuring the rate dependence of the mechanisms on site stress levels, and then using the rate data to analytically estimate the field life by means of computer models of the site environment. A correlation is established between the accelerated constant-stress testing and the time-varying field exposures. Test results are presented for two failure mechanisms for a module design featuring polyvinyl butyral encapsulant for the temperature range of 85 to 100 C and 85-percent relative humidity.

Otth, D. H.↗
NASA NTRS1986

The aging correlation (RH + t): Relative humidity (%) + temperature (deg C)

An aging correlation between corrosion lifetime, and relative humidity RH (%) and temperature t (C) has been reported in the literature. This aging correlation is a semi-log plot of corrosion lifetime on the log scale versus the interesting summation term RH(%) + t(C) on the linear scale. This empirical correlation was derived from observation of experimental data trends and has been referred to as an experimental law. Using electrical resistivity data of polyvinyl butyral (PVB) measured as a function of relative humidity and temperature, it was found that the electrical resistivity could be expressed as a function of the term RH(%) t(C). Thus, if corrosion is related to leakage current through an organic insulator, which, in turn, is a function of RH and t, then some partial theoretical validity for the correlation is indicated. This article describes the derivation of the term RH(%) t(C) from PVB electrical resistivity data.

Cuddihy, E. F.↗