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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS2005

Chemical colloids versus biological colloids: a comparative study for the elucidation of the mechanism of protein fiber formation

Fiber formation from murine serum amyloid A1 (SAA) was compared to the linear aggregation and fiber formation of colloidal gold particles. Here we report the similarities of these processes. Upon incubation with acetic acid, SAA misfolds and adopts a new conformation, which we termed saa. saa apparently is less soluble than SAA in aqueous solution; it aggregates and forms nucleation units and then fibers. The fibers appear as a string of the nucleation units. Additionally, an external electric field promotes saa fiber formation. These properties of saa are reminiscent of colloidal gold formation from gold ions and one-dimensional aggregation of the gold colloids. Colloidal gold particles were also found to be capable of aggregating one-dimensionally under an electric field or in the presence of polylysine. These gold fibers resembled in structure that of saa fibers. In summary, protein aggregation and formation of fibers appear to follow the generalized principles derived in colloidal science for the aggregation of atoms and molecules, including polymers such as polypeptides. The analysis of colloidal gold formation and of one-dimensional aggregation provides a simple model system for the elucidation of some aspects of protein fiber formation.

Colloids↗
NASA NTRS2007

The ISS Water Processor Catalytic Reactor as a Post Processor for Advanced Water Reclamation Systems

Advanced water processors being developed for NASA s Exploration Initiative rely on phase change technologies and/or biological processes as the primary means of water reclamation. As a result of the phase change, volatile compounds will also be transported into the distillate product stream. The catalytic reactor assembly used in the International Space Station (ISS) water processor assembly, referred to as Volatile Removal Assembly (VRA), has demonstrated high efficiency oxidation of many of these volatile contaminants, such as low molecular weight alcohols and acetic acid, and is considered a viable post treatment system for all advanced water processors. To support this investigation, two ersatz solutions were defined to be used for further evaluation of the VRA. The first solution was developed as part of an internal research and development project at Hamilton Sundstrand (HS) and is based primarily on ISS experience related to the development of the VRA. The second ersatz solution was defined by NASA in support of a study contract to Hamilton Sundstrand to evaluate the VRA as a potential post processor for the Cascade Distillation system being developed by Honeywell. This second ersatz solution contains several low molecular weight alcohols, organic acids, and several inorganic species. A range of residence times, oxygen concentrations and operating temperatures have been studied with both ersatz solutions to provide addition performance capability of the VRA catalyst.

Nalette, Tim↗
NASA NTRS2004

Liquid-Crystal Thermosets, a New Generation of High-Performance Liquid-Crystal Polymers

One of the major challenges for NASA's next-generation reusable-launch-vehicle (RLV) program is the design of a cryogenic lightweight composite fuel tank. Potential matrix resin systems need to exhibit a low coefficient of thermal expansion (CTE), good mechanical strength, and excellent barrier properties at cryogenic temperatures under load. In addition, the resin system needs to be processable by a variety of non-autoclavable techniques, such as vacuum-bag curing, resin-transfer molding (RTM), vacuum-assisted resin-transfer molding (VaRTM), resin-film infusion (RFI), pultrusion, and advanced tow placement (ATP). To meet these requirements, the Advanced Materials and Processing Branch (AMPB) at NASA Langley Research Center developed a new family of wholly aromatic liquid-crystal oligomers that can be processed and thermally cross-linked while maintaining their liquid-crystal order. All the monomers were polymerized in the presence of a cross-linkable unit by use of an environmentally benign melt-condensation technique. This method does not require hazardous solvents, and the only side product is acetic acid. The final product can be obtained as a powder or granulate and has an infinite shelf life. The obtained oligomers melt into a nematic phase and do not exhibit isotropization temperatures greater than the temperatures of decomposition (Ti > T(sub dec)). Three aromatic formulations were designed and tested and included esters, ester-amides, and ester-imides. One of the major advantages of this invention, named LaRC-LCR or Langley Research Center-Liquid Crystal Resin, is the ability to control a variety of resin characteristics, such as melting temperature, viscosity, and the cross-link density of the final part. Depending on the formulation, oligomers can be prepared with melt viscosities in the range of 10-10,000 poise (100 rad/s), which can easily be melt-processed using a variety of composite-processing techniques. This capability provides NASA with custom-made matrix resins that meet the required processing conditions for the fabrication of textile composites. Once the resin is in place, the temperature is raised to 375 C and the oligomers are cross-linked into a high-glass-transition-temperature (Tg) nematic network without releasing volatiles. The mechanical properties of the fully crosslinked, composite articles are comparable to typical composites based on commercially available epoxy resins.

Dingemans, Theo↗
NASA NTRS2011

Method and Apparatus for Forming Nanodroplets

This innovation uses partially miscible fluids to form nano- and microdroplets in a microfluidic droplet generator system. Droplet generators fabricated in PDMS (polydimethylsiloxane) are currently being used to fabricate engineered nanoparticles and microparticles. These droplet generators were first demonstrated in a T-junction configuration, followed by a cross-flow configuration. All of these generating devices have used immiscible fluids, such as oil and water. This immiscible fluid system can produce mono-dispersed distributions of droplets and articles with sizes ranging from a few hundred nanometers to a few hundred microns. For applications such as drug delivery, the ability to encapsulate aqueous solutions of drugs within particles formed from the droplets is desirable. Of particular interest are non-polar solvents that can dissolve lipids for the formation of liposomes in the droplet generators. Such fluids include ether, cyclohexane, butanol, and ethyl acetate. Ethyl acetate is of particular interest for two reasons. It is relatively nontoxic and it is formed from ether and acetic acid, and maybe broken down into its constituents at relatively low concentrations.

Ackley, Donald↗
NASA NTRS1994

Electrochemical Characterization of InP and GaAs Based Structures for Space Solar Cell Applications.

In this paper the emphasis is on accurate majority carrier concentration EC-V profiling of structures based on Indium Phosphide and Gallium Arsenide, using a newly developed electrolyte based on Hydrogen Flouride, Acetic Acid, Phosphoric Acid, 1-phenyl-2-propanamine and Ammonia Diflouride. Some preliminary data on the use of this electrolyte for determining the energy distribution of surface and deep states of these structures, applicable to fabrication process optimization and radiation induced defects studies of solar cells, are also provided.

Faur, Maria↗
NASA NTRS2017

Radiation Chemistry of Solid Acetone in the Interstellar Medium - A New Dimension to an Old Problem

A laboratory investigation of acetone, an interstellar and cometary molecule, has produced new results concerning its decomposition in a radiation environment. Mid-infrared spectroscopy has been used to follow amorphous acetone's destruction by ionizing radiation (1 MeV protons) at 20 K. Radiation products identified are the CH4, CO, and CO2 usually made in such experiments, along with ketene, allene, and the acetonyl radical, all identified here for the first time in irradiated solid acetone. Evidence for the reduction product 2-propanol was suggestive, but a firm identification could not be made either for it or for the C2 hydrocarbons (i.e., C2H6, C2H4, C2H2). The acetyl radical was not observed as a radiation product. Isotopically labeled reagents were used to demonstrate ketene formation and to emphasize that multiple approaches are needed for robust assignments of infrared spectral features of irradiated icy solids. Results from a supporting radiation experiment with isotopically labeled acetic acid are described. Comparisons are made to a previous study of acetone's stability in extraterrestrial radiation environments, and caution is urged in measuring and interpreting CO abundances in irradiated icy solids.

cometary molecule↗
NASA NTRS2019

Infrared Intensities and Molar Refraction of Amorphous Dimethyl Carbonate: Comparisons to Four Interstellar Molecules

The first measurements of infrared (IR) band intensities of solid dimethyl carbonate are presented along with measurements of this compound’s refractive index and density near 15 K, neither of which has been reported. Molar refractions are used to compare these results to other new data from ices made of methyl acetate, acetone, acetic acid, and acetaldehyde, four molecules known to exist in the interstellar medium. Comparisons are made to IR intensities taken from the literature on amorphous ices. The value and importance of comparisons based on molecular structures, to predict and test laboratory results, are highlighted.

Dimethyl carbonate; interstellar medium; amorphous↗
NASA NTRS2019

Infrared Intensities and Molar Refraction of Amorphous Dimethyl Carbonate – Comparisons to Four Interstellar Molecules

The first measurements of infrared (IR) band intensities of solid dimethyl carbonate are presented, along with measurements of this compound's refractive index and density near 15 K, neither of which has been reported. Molar refractions are used to compare these results to other new data from ices made of methyl acetate, acetone, acetic acid, and acetaldehyde, four molecules known to exist in the interstellar medium. Comparisons are made to IR intensities taken from the literature on amorphous ices. The value and importance of comparisons based on molecular structures, to predict and test laboratory results, is highlighted.

Reggie L. Hudson↗
NASA NTRS2017

Radiation Chemistry of Solid Acetone in the Interstellar Medium - A New Dimension to an Old Problem

A laboratory investigation of acetone, an interstellar and cometary molecule, has produced new results concerning its decomposition in a radiation environment. Mid-infrared spectroscopy has been used to follow amorphous acetone’s destruction by ionizing radiation (1 MeV protons) at 20 K. Radiation products identified are the CH4, CO, and CO2 usually made in such experiments, along with ketene, allene, and the acetonyl radical, all identified here for the first time in irradiated solid acetone. Evidence for the reduction product 2-propanol was suggestive, but a firm identification could not be made either for it or for the C2 hydrocarbons (i.e., C2H6, C2H4, C2H2). The acetyl radical was not observed as a radiation product. Isotopically labeled reagents were used to demonstrate ketene formation and to emphasize that multiple approaches are needed for robust assignments of infrared spectral features of irradiated icy solids. Results from a supporting radiation experiment with isotopically labeled acetic acid are described. Comparisons are made to a previous study of acetone’s stability in extraterrestrial radiation environments, and caution is urged in measuring and interpreting CO abundances in irradiated icy solids.

R. L. Hudson↗
NASA NTRS1990

Carbon-isotopic analysis of dissolved acetate

Heating of dried, acetate-containing solids together with oxalic acid dihydrate conveniently releases acetic acid for purification by gas chromatography. For determination of the carbon-isotopic composition of total acetate, the acetate-containing zone of the chromatographic effluent can be routed directly to a combustion furnace coupled to a vacuum system allowing recovery, purification, and packaging of CO2 for mass-spectrometric analysis. For analysis of methyl carbon, acetic acid can be cryogenically trapped from the chromatographic effluent, then transferred to a tube containing excess NaOH. The tube is evacuated, sealed, and heated to 500 degrees C to produce methane by pyrolysis of sodium acetate. Subsequent combustion of the methane allows determination of the 13C content at the methyl position in the parent acetate. With typical blanks, the standard deviation of single analyses is less than 0.4% for acetate samples larger than 5 micromoles. A full treatment of uncertainties is outlined.

Non-NASA Center↗
NASA NTRS1985

Dicarboxylic acid anhydride condensation with compounds containing active methylene groups. 4: Some 4-nitrophthalic anhydride condensation reactions

By 4-nitrophthalic anhydride condensation with acetoacetate in acetic anhydride and triethylamine solution with subsequent breakdown of the intermediate condensation product, 5-nitroindanedione-1,3 was obtained. A 4-nitrophthalic anhydride with acetic anhydride, according to reaction conditions, may yield two products: in the presence of potassium acetate and at high temperatures 4-(or 5-)-nitro-2-acetylbenzoic acid is formed: in the presence of triethylamine and at room temperature 5-( or 6-)-nitrophthalic acetic acid is isolated. A 4-nitrophthalic anhydride and malonic acid in pyridine solution according to temperature yield either 5-( or 6-)-nitrophthalic acetic acid or 4-(or 5-)-nitro-2-acetylbenzoic acid.

Oskaja, V.↗
NASA NTRS1991

Collagen telopeptides (cross-linking sites) play a role in collagen gel lattice contraction

Solubilized interstitial collagens will form a fibrillar, gel-like lattice when brought to physiologic conditions. In the presence of human dermal fibroblasts the collagen lattice will contract. The rate of contraction can be determined by computer-assisted planemetry. The mechanisms involved in contraction are as yet unknown. Using this system it was found that the rate of contraction was markedly decreased when collagen lacking telopeptides was substituted for native collagen. Histidinohydroxylysinonorleucine (HHL) is a major stable trifunctional collagen cross-link in mature skin that involves a carboxyl terminal, telopeptide site 16c, the sixteenth amino acid residue from the carboxy terminal of the telopeptide region of alpha 1 (I) in type I collagen. Little, if any, HHL was present in native, purified, reconstituted, soluble collagen fibrils from 1% acetic acid-extracted 2-year-old bovine skin. In contrast, HHL cross-links were present (0.22 moles of cross-link per mole of collagen) in lattices of the same collagen contracted by fibroblasts. However, rat tail tendon does not contain HHL cross-links, and collagen lattices made of rat tail tendon collagen are capable of contraction. This suggests that telopeptide sites, and not mature HHL cross-links per se, are essential for fibroblasts to contract collagen lattices. Beta-aminopropionitrile fumarate (BAPN), a potent lathyrogen that perturbs collagen cross-linking by inhibition of lysyl oxidase, also inhibited the rate of lattice cell contraction in lattices composed of native collagen. However, the concentrations of BAPN that were necessary to inhibit the contraction of collagen lattices also inhibited fibroblast growth suggestive of cellular toxicity. In accordance with other studies, we found no inhibition of the rate of lattice contraction when fibronectin-depleted serum was used. Electron microscopy of contracted gels revealed typical collagen fibers with a characteristic axial periodicity. The data provide evidence that collagen telopeptide sites play a role in collagen gel lattice contraction.

Non-NASA Center↗
NASA NTRS1979

Trace element release from estuarine sediments of South Mosquito Lagoon near Kennedy Space Center

Analytical partitioning of four trace metals in estuarine sediments collected from eight sites in South Mosquito Lagoon near Kennedy Space Center, in terms of four different categories was accomplished using four different extraction techniques. The concentrations of the four trace metals, Zn, Mn, Cd, and Cu, released in interstitial water extract, 1 N ammonium acetate extract, conc. HCl extract and fusion extract of sediments as well as their concentrations in water samples collected from the same location were determined using flame atomic absorption technique. From the analytical results the percentages of total amount of each metal distributed among four different categories, interstitial water phase, acetate extractable, acid extractable and detrital crystalline material, were determined. Our results suggest that analytical partitioning of trace metals in estuarine sediments may be used to study the mechanism of incorporation of trace metals with sediments from natural waters. A correlation between the seasonal variation in the concentration of acetate extractable trace metals in the sediment and similar variation in their concentration in water was observed. A mechanism for the release of trace metals from estuarine sediments to natural water is also suggested.

Menon, M. P.↗
NASA NTRS1991

Organic acids and selected nitrogen species for ABLE-3

The NASA Global Tropospheric Experiment (GTE) executed airborne science missions aboard the NASA Wallops Electra (NA429) in the North American high latitude (greater than 45 deg North) atmosphere during Jul. to Aug. 1988 and Jul. to Aug. 1990. These missions were part of GTE's Atmospheric Boundary Layer Experiment (ABLE). The 1988 mission , ABLE-3A, examined the ecosystems of Alaska as a source and/or sink for important tropospheric gases and particles, and gained new information on the chemical composition of the Arctic atmosphere during the summertime. During 1990 the second high latitude mission, ABLE-3B, focused on the Hudson Bay Lowland and Labrador regions of Canada. Both of these missions provided benchmark data sets on atmosphere biosphere exchange and atmospheric chemistry over largely uninhabited regions of North America. In support of the GTE/ABLE-3A and -3B field missions, the University of New Hampshire flew instrumentation aboard the Wallops Electra research aircraft to provide measurements of the trace gases nitric (HNO3), formic (HCOOH), and acetic (CH3COOH) acid. In addition, measurements were conducted to determine the major water soluble ionic composition of the atmospheric aerosol. For ABLE-3B, groundbased measurements of the acidic trace gases were also performed from the NASA micrometerological tower situated at Schefferville, Laborador. These measurements were aimed at assessing dry deposition of acidic gases to the taiga ecosystem in the Laborador region of Canada.

Talbot, Robert W.↗
NASA NTRS1971

Electroplating on titanium alloy

Activation process forms adherent electrodeposits of copper, nickel, and chromium on titanium alloy. Good adhesion of electroplated deposits is obtained by using acetic-hydrofluoric acid anodic activation process.

Lowery, J. R.↗