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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 955 records · Page 53
All sourcesNASA NTRSDOE OSTI
NASA NTRS2010

Radiation Protection Using Carbon Nanotube Derivatives

BHA and BHT are well-known food preservatives that are excellent radical scavengers. These compounds, attached to single-walled carbon nanotubes (SWNTs), could serve as excellent radical traps. The amino-BHT groups can be associated with SWNTs that have carbolyxic acid groups via acid-base association or via covalent association. The material can be used as a means of radiation protection or cellular stress mitigation via a sequence of quenching radical species using nano-engineered scaffolds of SWNTs and their derivatives. It works by reducing the number of free radicals within or nearby a cell, tissue, organ, or living organism. This reduces the risk of damage to DNA and other cellular components that can lead to chronic and/or acute pathologies, including (but not limited to) cancer, cardiovascular disease, immuno-suppression, and disorders of the central nervous system. These derivatives can show an unusually high scavenging ability, which could prove efficacious in protecting living systems from radical-induced decay. This technique could be used to protect healthy cells in a living biological system from the effects of radiation therapy. It could also be used as a prophylactic or antidote for radiation exposure due to accidental, terrorist, or wartime use of radiation- containing weapons; high-altitude or space travel (where radiation exposure is generally higher than desired); or in any scenario where exposure to radiation is expected or anticipated. This invention s ultimate use will be dependent on the utility in an overall biological system where many levels of toxicity have to be evaluated. This can only be assessed at a later stage. In vitro toxicity will first be assessed, followed by in vivo non-mammalian screening in zebra fish for toxicity and therapeutic efficacy.

Conyers, Jodie L., Jr.↗
DOE OSTI2014

Preliminary Report: Effects of Irradiation and Thermal Exposure on Elastomeric Seals for Cask Transportation and Storage

A testing and analysis approach to predict the sealing behavior of elastomeric seal materials in dry storage casks and evaluate their ability to maintain a seal under thermal and radiation exposure conditions of extended storage and beyond was developed, and initial tests have been conducted. The initial tests evaluate the aging response of EPDM elastomer O-ring seals. The thermal and radiation exposure conditions of the CASTOR® V/21 casks were selected for testing as this cask design is of interest due to its widespread use, and close proximity of the seals to the fuel compared to other cask designs leading to a relatively high temperature and dose under storage conditions. A novel test fixture was developed to enable compression stress relaxation measurements for the seal material at the thermal and radiation exposure conditions. A loss of compression stress of 90% is suggested as the threshold at which sealing ability of an elastomeric seal would be lost. Previous studies have shown this value to be conservative to actual leakage failure for most aging conditions. These initial results indicate that the seal would be expected to retain sealing ability throughout extended storage at the cask design conditions, though longer exposure times are needed to validate this assumption. The high constant dose rate used in the testing is not prototypic of the decreasingly low dose rate that would occur under extended storage. The primary degradation mechanism of oxidation of polymeric compounds is highly dependent on temperature and time of exposure, and with radiation expected to exacerbate the oxidation.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2019

Microwave Irradiation Intensified Process for Scalable Functional Device Assembly

The environment pollution is a serious issue worldwide for human beings, which calls for ever-increasing demand towards environmental protection. Efficient enabling and utilization of various functional devices represent an essential solution to pursue the environment sustainability. Nanotechnology is emerging as an effective approach to improve the efficiency of functional devices for a variety of environmental applications. For example, the nanomaterials-based catalysts are being widely used in air pollution control, enabling catalysts with significantly enhanced performance. Scalable integration of functional nanostructural entities such as nanoparticles, nanowires, nanosheets into applicable three-dimensional (3-D) platform holds the keys of industrial-relevant manufacture of high-efficiency catalytic devices for emission control. Among all the integration approaches, the wet-chemical based integration is one of the top options due to its advantages in low-cost, flexibility in substrate geometry and composition, ease of operation, and high repeatability. The wet-chemical based processes usually require continuous heating to initiate the chemical reactions, which is regularly achieved by conventional resistive heating. However, such conventional heating method is plaqued by a poor heating efficiency. Moreover, the conventional heating is not suitable for those substrates with three-dimensional (3D) or complex geometry since it hardly provides sufficient heat transfer and mass transport within substrates, leading to poor uniformity of nanostructure deposition and low production rate. Thus, there is urgent demand to develop high-efficiency wet-chemical based integration strategy for nanostructured functional devices. In this project, a novel microwave-irradiation-intensified hydrothermal manufacturing process was developed for scalable manufacture of nanostructured monolithic catalytic devices. A wide array of metal oxide nanostructured coatings has been in situ grown on various 3D substrates for emission control applicaitons such as cordierite honeycombs and silicon carbide honeycomb. The growth efficiency, production rate, and distribution uniformity of nanostructure coatings obtained from microwave heating and conventional heating are investigated, which reveals the boosting effect of microwave irradiation on hydrothermal reactions. The silicon carbide honeycomb is found to be more favorable to microwave adsorption in contrast to cordierite honeycomb, and the corresponding reaction mechanism is studied. The obtained catalysts are used for catalytic oxidation of Volatile Organic Compounds (VOCs), showing excellent catalytic performance at low temperature for various compounds. As the proof of concept, the design of integrated manufacturing system for the microwave irradiation assisted continuous production of nanostructure array based monolithic catalysts is presented, which holds the key to mass production of monolithic catalysts in near future.

42 ENGINEERING↗
DOE OSTI2015

High efficiency and brightness fluorescent organic light emitting diode by triplet-triplet fusion

A first device is provided. The first device further comprises an organic light emitting device. The organic light emitting device further comprises an anode, a cathode, and an emissive layer disposed between the anode and the cathode. The emissive layer may include an organic host compound and at least one organic emitting compound capable of fluorescent emission at room temperature. Various configurations are described for providing a range of current densities in which T-T fusion dominates over S-T annihilation, leading to very high efficiency fluorescent OLEDs.

42 ENGINEERING↗
DOE OSTI2021

Severity factor kinetic model as a strategic parameter of hydrothermal processing (steam explosion and liquid hot water) for biomass fractionation under biorefinery concept

Hydrothermal processes are an attractive clean technology and cost-effective engineering platform for bio-refineries based in the conversion of biomass to biofuels and high-value bioproducts under the basis of sustainability and circular bioeconomy. The deep and detailed knowledge of the structural changes by the severity of biomasses hydrothermal fractionation is scientifically and technological needed in order to improve processes effectiveness, reactors designs, and industrial application of the multi-scale target compounds obtained by stream explosion and liquid hot water systems. The concept of the severity factor [log 10 (R 0 )] established > 30 years ago, continue to be a useful index that can provide a simple description of the relationship between the operational conditions for biomass fractionation in second generation of biorefineries. Furthermore, this review develops a deep explanation of the hydrothermal severity factor based in lignocellulosic biomass fractionation with emphasis in research advances, pretreatment operations and the applications of severity factor kinetic model.

09 BIOMASS FUELS↗
NASA NTRS1973

Some environmental considerations relating to the interaction of the solid rocket motor exhaust with the atmosphere: Predicted chemical composition of exhaust species and predicted conditions for the formation of HCl aerosol

The exhaust products of a solid rocket motor using as propellant 14% binder, 16% aluminum, and 70% (wt) ammonium perchlorate consist of hydrogen chloride, water, alumina, and other compounds. The equilibrium and some frozen compositions of the chemical species upon interaction with the atmosphere were computed. The conditions under which hydrogen chloride interacts with the water vapor in humid air to form an aerosol containing hydrochloric acid were computed for various weight ratios of air/exhaust products. These computations were also performed for the case of a combined SRM and hydrogen-oxygen rocket engine. Regimes of temperature and relative humidity where this aerosol is expected were identified. Within these regimes, the concentration of HCL in the aerosol and weight fraction of aerosol to gas phase were plotted. Hydrochloric acid aerosol formation was found to be particularly likely in cool humid weather.

Rhein, R. A.↗
NASA NTRS1987

Hypersonic structures and materials - A progress report

The weight of a hypersonic, airbreathing SSTO vehicle may be more critical than for any previous aerospacecraft; an evaluation is accordingly made of the development status and applicability of intermetallic compounds, metal-matrix composites, carbon-carbon composites, ceramics, and ceramic-matrix composites applicable to SSTO craft primary structures. Aerothermal, aerothermoelastic, and acoustic loads are high because the airbreathing SSTO vehicle must follow a high dynamic pressure trajectory in order to achieve the requisite propulsive efficiency. Attention is given to the prospects for integral cryogenic tankage and actively hydrogen-cooled airframe and engine structures.

Jackson, L. Robert↗
NASA NTRS1997

Cure Chemistry of Phenylethynyl Terminated Oligomers

The ability to process high performance polymers into quality, void-free composites has been significantly advanced using oligomers terminated with reactive groups which cure or crosslink at elevated temperature without the evolution of volatile byproducts. Several matrix resin systems of considerable interest to the aerospace community utilize phenylethynyl-terminated imide (PETI) technology to achieve this advantage. The present paper addresses the cure chemistry of PETI oligomers. The thermal cure of a low molecular weight model compound was studied using a variety of analytical techniques including differential scanning calorimetry, Fourier transform infrared spectroscopy, and liquid chromatography-mass spectroscopy. The studies indicate an extremely complex cure process. Many stable products were isolated and this paper reports current work on identification of those products. The intent of this research is to provide fundamental insight into the molecular structure of the cured PETI engineering materials so that performance and durability can be more fully assessed.

Wood, Karen H.↗
DOE OSTI2019

Structure of an engineered multidrug transporter MdfA reveals the molecular basis for substrate recognition

MdfA is a prototypical H + -coupled multidrug transporter that is characterized by extraordinarily broad substrate specificity. The involvement of specific H-bonds in MdfA-drug interactions and the simplicity of altering the substrate specificity of MdfA contradict the promiscuous nature of multidrug recognition, presenting a baffling conundrum. Here we show the X-ray structures of MdfA variant I239T/G354E in complexes with three electrically different ligands, determined at resolutions up to 2.2 Å. Our structures reveal that I239T/G354E interacts with these compounds differently from MdfA and that I239T/G354E possesses two discrete, non-overlapping substrate-binding sites. Our results shed new light on the molecular design of multidrug-binding and protonation sites and highlight the importance of often-neglected, long-range charge-charge interactions in multidrug recognition. Beyond helping to solve the ostensible conundrum of multidrug recognition, our findings suggest the mechanistic difference between substrate and inhibitor for any H + -dependent multidrug transporter, which may open new vistas on curtailing efflux-mediated multidrug resistance.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2014

Surface-engineered core-shell nano-size ferrites and their antimicrobial activity

We report the results of biological study on core-shell structured MFe{sub 2}O{sub 4} (where M = Co, Mn, Ni) nanoparticles and influence of silica- DEG dual coating on their antimicrobial activity. Spherical MFe{sub 2}O{sub 4} nanoparticles were prepared via a Co-precipitation method. The microstructures and morphologies of these nanoparticles were studied by x-ray diffraction and FTIR. The antimicrobial activity study carried out in nutrient agar medium with addition of antimicrobial synthesis compound which is tested for its activity against different types of bacteria.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Hydrogen retention in lithium on metallic walls from “in vacuo” analysis in LTX and implications for high-Z plasma-facing components in NSTX-U

The application of lithium to plasma-facing components (PFCs) has long been used as a technique for wall conditioning in magnetic confinement devices to improve plasma performance. Determining the characteristics of PFCs at the time of exposure to the plasma, however, is difficult because they can only be analyzed after venting the vacuum vessel and removing them at the end of an operational period. The Materials Analysis and Particle Probe (MAPP) addresses this problem here by enabling PFC samples to be exposed to plasmas, and then withdrawn into an analysis chamber without breaking vacuum. The MAPP system was used to introduce samples that matched the metallic PFCs of the Lithium Tokamak Experiment (LTX). Lithium that was subsequently evaporated onto the walls also covered the MAPP samples, which were then subject to LTX discharges. In vacuo extraction and analysis of the samples indicated that lithium oxide formed on the PFCs, but improved plasma performance persisted in LTX. The reduced recycling this suggests is consistent with separate surface science experiments that demonstrated deuterium retention in the presence of lithium oxide films. Since oxygen decreases the thermal stability of the deuterium in the film, the release of deuterium was observed below the lithium deuteride dissociation temperature. This may explain what occurred when lithium was applied to the surface of the NSTX Liquid Lithium Divertor (LLD). The LLD had segments with individual heaters, and the deuterium-alpha emission was clearly lower in the cooler regions. The plan for NSTX-U is to replace the graphite tiles with high-Z PFCs, and apply lithium to their surfaces with lithium evaporation. Experiments with lithium coatings on such PFCs suggest that deuterium could still be retained if lithium compounds form, but limiting their surface temperatures may be necessary.

42 ENGINEERING↗
DOE OSTI2014

Layer-structured hexagonal (BN)C semiconductor alloys with tunable optical and electrical properties

Hexagonal boron nitride carbon, h(BN){sub 1-x}(C{sub 2}){sub x}, semiconductor alloys have been grown on sapphire substrates by metal-organic chemical vapor deposition. Bandgap tuning through compositional variation has been demonstrated via optical absorption measurements. Furthermore, an enhancement of approximately 10 orders of magnitude in the electrical conductivity has been attained by increasing the carbon concentration (x) from 0 to 0.21. Experimental results revealed evidences that the critical carbon concentration x{sub c} to form the homogenous h(BN){sub 1-x}(C{sub 2}){sub x} alloys, or the carbon solubility in hBN is about 3.2% at a growth temperature of 1300 °C before carbon clusters form. Based on the predicted phase diagram of cubic (BN){sub 1-x}(C{sub 2}){sub x} and the excellent matches in the structural and thermal properties of hBN and graphite, it is expected that homogenous h(BN){sub 1-x}(C{sub 2}){sub x} alloys with higher x can be achieved and the alloy miscibility gap can be reduced or completely removed by increasing the growth temperature. This is a huge advantage over the InGaN alloy system in which InN decomposes at high temperatures and high growth temperature cannot be utilized to close the miscibility gap. The results indicate that the h(BN){sub 1-x}(C{sub 2}){sub x} alloy system has the potential to tackle the challenging issues facing the emerging two-dimension materials beyond graphene, which include realizing the bandgap engineering, conductivity control, and large wafers of homogeneous films.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Strain control magnetocrystalline anisotropy of Ta/FeCo/MgO heterostructures

Using ab initio electronic structure calculations, we have investigated the effect of epitaxial strain on magnetocrystalline anisotropy (MCA) of Ta/FeCo/MgO heterostructure. At small expansive strains on the FeCo layer, the system exhibits perpendicular MCA (PMA). Strain not only has a profound effect on the value of MCA but also induces a switching of magnetic easy axis. Analysis of the energy- and k-resolved distribution of orbital characters of the minority-spin band reveals that a significant contribution to PMA at zero strain arises from the spin-orbit coupling between occupied d{sub x{sup 2}−y{sup 2}} and unoccupied d{sub xy} states, derived from Fe at the FeCo/MgO interface. The strain effect is attributed to strain-induced shifts of spin-orbit coupled d-states. Our work demonstrates that strain engineering can open a viable pathway towards tailoring magnetic properties for spintronic applications.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS1972

Lubrication handbook for use in the space industry. Part A: Solid lubricants. Part B: Liquid lubricants

This handbook provides a ready reference for many of the solid and liquid lubricants used in the space industry. Lubricants and lubricant properties are arranged systematically so that designers, engineers, and maintenance personnel in the space industry can conveniently locate data needed for their work. The handbook is divided into two major parts. Part A is a compilation of chemical and physical property data of more than 250 solid lubricants, bonded solid lubricants, dispersions and composites. Part B is a compilation of chemical and physical property data of more than 250 liquid lubricants, greases, oils, compounds and fluids. The listed materials cover a broad spectrum, from manufacturing and ground support to hardware applications for missiles and spacecraft.

Campbell, M. E.↗
NASA NTRS2003

Columbia Accident Investigation Board. Volume One

The Columbia Accident Investigation Board's independent investigation into the February 1, 2003, loss of the Space Shuttle Columbia and its seven-member crew lasted nearly seven months. A staff of more than 120, along with some 400 NASA engineers, supported the Board's 13 members. Investigators examined more than 30,000 documents, conducted more than 200 formal interviews, heard testimony from dozens of expert witnesses, and reviewed more than 3,000 inputs from the general public. In addition, more than 25,000 searchers combed vast stretches of the Western United States to retrieve the spacecraft's debris. In the process, Columbia's tragedy was compounded when two debris searchers with the U.S. Forest Service perished in a helicopter accident. This report concludes with recommendations, some of which are specifically identified and prefaced as 'before return to flight.' These recommendations are largely related to the physical cause of the accident, and include preventing the loss of foam, improved imaging of the Space Shuttle stack from liftoff through separation of the External Tank, and on-orbit inspection and repair of the Thermal Protection System. The remaining recommendations, for the most part, stem from the Board's findings on organizational cause factors. While they are not 'before return to flight' recommendations, they can be viewed as 'continuing to fly' recommendations, as they capture the Board's thinking on what changes are necessary to operate the Shuttle and future spacecraft safely in the mid- to long-term. These recommendations reflect both the Board's strong support for return to flight at the earliest date consistent with the overriding objective of safety, and the Board's conviction that operation of the Space Shuttle, and all human space-flight, is a developmental activity with high inherent risks.

SPACE SHUTTLE COLUMBIA↗
NASA NTRSDate not supplied

The Inspectability Metric: A Formalized System Of Measurement Enabling The Design For Inspection Framework

Nondestructive evaluation (NDE) engineers are often confronted with structural design choices that present challenges to meeting inspection requirements. These challenges, at best, increase the resources needed to design an inspection solution and, at worst, require resource intensive redesign of the structure. If the inspectability of the structure can be determined early in the design cycle, these challenging inspection scenarios can be avoided. The emergence of additive manufacturing has further compounded this problem by enabling the creation of highly optimized structures with no regard to inspection constraints. Design for inspection (DFI) offers a framework to integrate nondestructive evaluation (NDE) into the design process to alleviate the mechanisms that produce uninspectable designs. DFI is the concept of including inspectability in a multi-objective optimization framework so that it can be considered in parallel to other metrics such as mass and manufacturability. This allows rapid evaluation of the trade-off between design metrics to find solutions that meet the inspection needs of a particular material system, structural concept, or vehicle program. To enable DFI, there must be a system by which the inspectability of a structure can be measured. This system must be agile to produce results quickly, it must be versatile to work with the type of incomplete information one would encounter early in the design process (such as lack of inspection requirements), and it must be delivered in a form that is easily understood by designers. To meet this need, this presentation introduces the novel inspectability metric as a system to measure inspectability. The inspectability metric is a standardized, automation friendly procedure that uses simulations to determine inspectability. Along with guidelines to properly process designs and integrate with existing workflows, the inspectability metric provides a suite of simulation tests to interrogate the ability to find defects and the sensitivity to variability. The testing rubric is designed to maximize the coverage of the parameter space while minimizing the number of simulations needed. The inspectability metric has been in development in collaboration with industry partners to ensure compatibility with modern simulation tools and aerospace design workflows. In this study, we will demonstrate how the inspectability metric is able to determine the inspectability of multiple types of structures, including aerospace composites and additively manufactured parts. We will then show how the inspectability score can be plugged into existing design optimization tasks, such as structural sizing algorithms or design for manufacturing (DFM) frameworks.

Design for inspection↗
DOE OSTI2017

Microstructure Reconstruction of Sheet Molding Composite Using a Random Chips Packing Algorithm

Fiber-reinforced polymer composites are strong candidates for structural materials to replace steel and light alloys in lightweight vehicle design because of their low density and relatively high strength. In the integrated computational materials engineering (ICME) development of carbon fiber composites, microstructure reconstruction algorithms are needed to generate material microstructure representative volume element (RVE) based on the material processing information. The microstructure RVE reconstruction enables the material property prediction by finite element analysis (FEA)This paper presents an algorithm to reconstruct the microstructure of a chopped carbon fiber/epoxy laminate material system produced by compression molding, normally known as sheet molding compounds (SMC). The algorithm takes the result from material’s manufacturing process as inputs, such as the orientation tensor of fibers, the chopped fiber sheet geometry, and the fiber volume fraction. The chopped fiber sheets are treated as deformable rectangle chips and a random packing algorithm is developed to pack these chips into a square plate. The RVE is built in a layer-by-layer fashion until the desired number of lamina is reached, then a fine tuning process is applied to finalize the reconstruction. Compared to the previous methods, this new approach has the ability to model bended fibers by allowing limited amount of overlaps of rectangle chips. Furthermore, the method does not need SMC microstructure images, for which the image-based characterization techniques have not been mature enough, as inputs. Case studies are performed and the results show that the statistics of the reconstructed microstructures generated by the algorithm matches well with the target input parameters from processing.

Huang, Tianyu↗
DOE OSTI2017

Measurements and Prediction of Sooting Tendencies of Pure Hydrocarbons

The amount of soot formed in combustion devices such as engines depends strongly on the chemical structure of the fuel. Over the past 10 years we have measured quantitative sooting tendencies for hundreds of pure hydrocarbons representative of those in practical fuels. The sooting tendencies have been characterized in terms of Yield Sooting Index (YSI), which is based on the amount of soot formed in a methane/air reference flame when a small amount of the test compound is doped into the fuel. In this new collaborative project we are developing a Quantitative Structure-Activity Relationship (QSAR) model from these results; this model can be used to predict YSI for new hydrocarbons of interest and to understand the details of the underlying chemistry. The model uses molecular descriptors to describe the structure of each compound in the database, and it predicts YSI with a feed-forward artificial neural network trained with the measured values. It has a rigorously defined applicability domain and its performance has been tested by both internal and external validation. New measurements have been performed to extend the applicability domain towards advanced biofuels and for external validation.

30 DIRECT ENERGY CONVERSION↗