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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 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Introduction of a Synthetic CO 2 -fixing Photorespiratory Bypass into a Cyanobacterium

Global photosynthetic productivity is limited by the enzymatic assimilation of CO 2 into organic carbon compounds. Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), the carboxylating enzyme of the Calvin-Benson cycle, poorly discriminates between CO 2 and O 2 , leading to photorespiration and the loss of fixed carbon and nitrogen. With the advent of synthetic biology, it is now feasible to design, synthesize, and introduce biochemical pathways in vivo. We engineered a synthetic photorespiratory bypass based on the 3-hydroxypropionate bi-cycle into the model cyanobacterium, Synechococcus elongatus sp. PCC 7942. The heterologously expressed cycle is designed to function as both a photorespiratory bypass and an additional CO 2 -fixing pathway, supplementing the Calvin-Benson cycle. We demonstrate the function of all six introduced enzymes and identify bottlenecks to be targeted in subsequent bioengineering. These results have implications for efforts to improve photosynthesis and for the “green” production of high value products of biotechnological interest.

3-Hydroxypropionate Bi-cycle↗
NASA NTRSDate not supplied

Strategies Toward Lunar Dust Adhesion Mitigation

Recently, the NASA Space Technology Mission Directorate solicited feedback to prioritize shortfalls, which were defined as technology areas needed to enable future exploration missions. Lunar dust mitigation emerged as a critical area and is cross-cutting with many of the highest ranked shortfalls with passive dust mitigation technologies being directly ranked in the top 50. Hazards associated with lunar dust are ubiquitous across all aspects of long duration lunar surface missions, whether crewed or robotic, due to the abrasive, electrostatically charged, and chemically reactive properties of lunar dust. Compounding the issue, lunar dust moves across the lunar surface due to levitation, twilight craters, and plume-surface interactions, which can result in particle velocities exceeding 1 km/h. To address lunar dust challenges, NASA is developing active and passive adhesion mitigation technologies to address specific mission needs, including electrodynamic dust screens, piezoelectric materials, biomimetic engineered surfaces, among many others. Additionally, abrasion-resistant materials are being evaluated for applications for use near landing sites and in surface manipulation and excavation equipment. These approaches, as well as test methodologies both in the laboratory and on the lunar surface to evaluate technology efficacy, will be described.

Dust Mitigation↗
DOE OSTI2015

Formation of the domain structure in CLN under the pyroelectric field induced by pulse infrared laser heating

The evolution of the self-assembled quasi-regular micro- and nanodomain structures after pulse infrared laser irradiation in congruent lithium niobate crystal was studied by in situ optical observation. Several scenarios of domain kinetics represented covering of the irradiated zone by nets of the separated domain chains and rays have been revealed. The time dependence of the total domain length was analyzed in terms of modified Kolmogorov-Avrami theory. The domain structure evolution was attributed to the action of pyroelectric field appeared during cooling. The time dependence of the spatial distribution of the pyroelectric field during pulse laser heating and subsequent cooling was calculated by finite element method. The results of computer simulation allowed us to explain the experimental results and can be used for creation of tailored domain structures thus opening the new abilities of the submicron-scale domain engineering in ferroelectrics.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Optimized surface topography of thermoplastics blends modified by graphene

Polyacrilonitrile (PAN)/ Polyvinylfloride (PVDF) blends were modified by loading the graphene (0.5 to 1.5 wt %). The presence of graphene reveals the interesting surface properties. The decrease in surface roughness as function of graphene loading was confirmed by the topographic method of recording (two and three dimensional images) with atomic force microscope (AFM). The blends become smoother in nature due to occupied smaller surface area of graphene. This property may be useful for several applications in the marine, naval, nuclear domain and engineering applications as barrier medium.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2013

Predictive Engineering Tools for Injection-Molded Long-Carbon-Fiber Thermoplastic Composites - FY13 Fourth Quarterly Report

This quarterly report summarizes the status of the project planning to obtain all the approvals required for a Cooperative Research and Development Agreement (CRADA) with Autodesk, Inc., Toyota Motor Engineering and Manufacturing North America (Toyota), and Magna Exterior and Interiors Corporation (Magna). The final CRADA documents processed by PNNL’s Legal Services were submitted to all the parties for signatures.

Compounding↗
DOE OSTI2016

Characterization of Products from Fast Micropyrolysis of Municipal Solid Waste Biomass

Biomass feedstock costs remain one of the largest impediments to biofuel production economics. Municipal solid waste (MSW) represents an attractive feedstock with year-round availability, an established collection infrastructure paid for by waste generators, low cost and the potential to be blended with higher cost feedstocks to reduce overall feedstock costs. Paper waste, yard waste and construction and demolition waste (C&D) were examined for their applicability in the pyrolysis conversion pathway. Paper waste consisted of non-recyclable paper such as mixed low grade paper, food and beverage packaging, kitchen paper wastes and coated paper; yard waste consisted of grass clippings and C&D wastes consisted of engineered wood products obtained from a construction waste landfill. We tested the waste materials for thermochemical conversion potential using a bench scale fast micro-pyrolysis process. Bio-oil yields were the highest for the C&D materials and lowest for the paper waste. The C&D wastes had the highest level of lignin derived compounds (phenolic and cyclics) while the paper waste had higher levels of carbohydrate derived compounds (aldehydes, organic acids, ketones, alcohols and sugar derived). But, the paper material had higher amounts of lignin derived compounds than expected based upon lignin content that is likely due to the presence of polyphenolic resins used in paper processing. The paper and yard wastes had significantly higher levels of ash content than the C&D wastes (14-15% versus 0.5-1.3%), which further correlated to higher levels of alkali and alkaline earth metals, which are known to reduce pyrolysis bio-oil yields. There appeared to be an inverse correlation of both calcium and potassium content with the amount of chromatographic product peaks, indicative of cracking reactions occurring during product formation. Furthermore the effect of acid washing was evaluated for grass clipping and waste paper and the bio-oil yield was increased from 58% to 73% and 67% to 73%, respectively.

09 BIOMASS FUELS↗
NASA NTRS1991

Mining the air - Resources of other worlds may reduce mission costs

It is proposed that the mining of resources on another planet to support operations there and also to provide a means for the return trip to earth provides a less expensive way to send humans beyond low earth orbit to live on the moon and to explore Mars. Since a large fraction of any chemical propellant combination is the oxidizer that burns with the fuel to generate the rocket jet, and for life support, the generation of oxygen from any of its atmospheric or mineral compounds is a valuable capability. Such materials include the lunar minerals ilmenite and anorthite, Martian permafrost, water ice at the Martian poles, and atmospheric carbon dioxide on Mars. The possibilities of developing such technologies are discussed and the prospects of developing building materials for such facilities from local resources are considered. The role of the Space Engineering Research Center at the University of Arizona in exploring the use of local planetary resources is noted.

Ramohalli, Kumar↗
DOE OSTI2015

Effect of the oxide layer on current-induced spin-orbit torques in Hf|CoFeB|MgO and Hf|CoFeB|TaO{sub x} structures

We study the effect of the oxide layer on the current-induced spin-orbit torques (SOTs) in perpendicularly magnetized Hf|CoFeB|MgO (MgO-capped) or Hf|CoFeB|TaO{sub x} (TaO{sub x}-capped) structures. The effective fields corresponding to both the field-like and damping-like current-induced SOTs are characterized using electric transport measurements. Both torques are found to be significantly stronger in MgO-capped structures than those in TaO{sub x}-capped structures. The difference in field-like and damping-like SOTs in the different structures may be attributed to the different Rashba-like Hamiltonian, arising from the difference in the electric potential profiles across the oxide|ferromagnet interfaces in the two cases, as well as possible structural and oxidation differences in the underlying CoFeB and Hf layers. Our results show that the oxide layer in heavy-metal|ferromagnet|oxide trilayer structures has a very significant effect on the generated SOTs for manipulation of ferromagnetic layers. These findings could potentially be used to engineer SOT devices with enhanced current-induced switching efficiency.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

Verification of Subcritical Limits in ANSI/ANS-8.1-2014

The first edition of the current American National Standards Institute (ANSI)/American Nuclear Society (ANS) standard ANSI/ANS-8.1-2014, “Nuclear Criticality Safety in Operations with Fissionable Materials Outside Reactors,” was published in 1964 as ASA N6.1-1964, “Safety Standard for Operations with Fissionable Materials Outside Reactors.” In 1969, that standard was revised as ANSI N16.1-1969, “Nuclear Criticality Safety in Operations with Fissionable Materials Outside Reactors.” ANSI N16.1-1969 includes a variety of subcritical limits (SCLs) for uniform aqueous solutions and metals containing fissile nuclides of 233 U, 235 U, and 239 Pu. Furthermore, SCLs are also included for uranium-water lattices. In the 1983 version of ANSI/ANS-8.1 (a revision of ANSI N16.1-1975), the suite of SCLs in the standard was expanded to include 235 U enrichment limits for homogeneous uranium-water mixtures and dry/damp oxides, uniform aqueous solutions of low-enriched uranium, and uniform aqueous mixtures of Pu(NO 3 ) 4 containing 240Pu in addition to the SCLs included in ANSI N16.1-1969. The SCLs have changed little in subsequent revisions (ANSI/ANS-8.1-1998 and ANSI/ANS-8.1-2014). The ANSI/ANS-8.1-2014 standard is currently being revised to include new SCLs (uranium metal and compounds with enrichments up to 20 wt% 235 U) and possible updates to the current SCLs already in the standard, although these new/updated SCLs will not be available to the nuclear criticality safety (NCS) community for a number of years. The original bases for these SCLs were documented in papers in journals such as Nuclear Science and Engineering and in ANS meeting transactions; however, these bases are ambiguous enough that sites and regulators in the United States have not widely endorsed them for safety purposes. Overall, the purpose of this paper is to present the results of a comparison study for the SCLs in the ANSI/ANS-8.1-2014 standard using modern codes (SCALE and MCNP) and cross sections (ENDF/B-VIII.0) to provide some assurance about their quality (bias and bias uncertainty) for use in NCS applications and for consideration by the ANS-8.1 Working Group as a reference for future revisions.

42 ENGINEERING↗
DOE OSTI2018

Rapid, parallel identification of pathways for catabolism of lignin-derived aromatic compounds in Novosphingobium aromaticivorans

Transposon mutagenesis is a powerful technique in microbial genetics for the identification of genes in uncharacterized pathways. Recently, the throughput of transposon mutagenesis techniques has been dramatically increased through the combination of DNA barcoding and high-throughput sequencing. Here we show that, when applied to catabolic pathways, barcoded transposon libraries can be used to distinguish redundant pathways, decompose complex pathways into substituent modules, discriminate between enzyme homologs, and rapidly identify previously-hypothetical enzymes in an unbiased genome-scale search. We use this technique to identify two genes, which we name desC and desD , are involved in the degradation of the lignin-derived aromatic compound sinapic acid in the non-model bacterium Novosphingobium aromaticivorans . We show that DesC is a methyl-esterase acting on an intermediate formed during sinapic acid catabolism, providing the last enzyme in a proposed catabolic pathway. Here, this approach will be particularly useful in the identification of complete pathways suitable for heterologous expression in metabolic engineering.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Manipulation of glycogen and sucrose synthesis increases photosynthetic productivity in cyanobacteria

Photosynthetic productivity is limited by low energy conversion efficiency in naturally evolved photosynthetic organisms, via multiple mechanisms that are not fully understood. Here we show evidence that extends recent findings that cyanobacteria use “futile” cycles in the synthesis and degradation of carbon compounds to dissipate ATP. Reduction of the glycogen cycle or the sucrose cycle in the model cyanobacterium Synechocystis 6803 led to redirection of cellular energy toward faster growth under simulated outdoor light conditions in photobioreactors that was accompanied by higher energy charge [concentration ratio of ATP/(ATP + ADP)]. Such manipulation of energy metabolism may have potential in engineering microalgal chassis cells to increase productivity of biomass or target metabolites.

09 BIOMASS FUELS↗
NASA NTRS1998

Crystal Growth of Mixed Optical Materials With the Automatic Czochralski Puller

Most of optical and semiconductor single crystalline materials produced in the electronic industry is grown with the Czochralski technique. This is the only technique capable of producing large high quality single crystals in a reasonable amount of time. The technique originated, and took its name, from pioneering work by Polish engineer J. Czochralski in 1917, who pulled single crystal wires (fibers) of low melting point metals from the melt in order to determine the maximum speeds at which they could be crystallized. The technique has been modified and its application has been extended first to the growth of silicon and later to a very wide range of compound semiconductors, metals, oxides and halides. It is now the dominant technique for the wide range of materials in the electronic industries. Czochralski growth is initiated by dipping a seed crystal of a chosen crystallographic orientation onto the surface of a melt contained in the heated crucible. The seed is then slowly withdrawn, solidifying the adherent column of the melt in steady state at an average rate given by the sum of the pulling rate and the rate of lowering the solid-liquid interface due to the depletion of the melt in the crucible. The control of the desired crystal diameter is achieved by closely controlling the heat balance at the solid-liquid interface.

Loutts, George B.↗
DOE OSTI2024

Catabolism of β-5 linked aromatics by Novosphingobium aromaticivorans

ABSTRACT Aromatic compounds are an important source of commodity chemicals traditionally produced from fossil fuels. Aromatics derived from plant lignin can potentially be converted into commodity chemicals through depolymerization followed by microbial funneling of monomers and low molecular weight oligomers. This study investigates the catabolism of the β-5 linked aromatic dimer dehydrodiconiferyl alcohol (DC-A) by the bacterium Novosphingobium aromaticivorans . We used genome-wide screens to identify candidate genes involved in DC-A catabolism. Subsequent in vivo and in vitro analyses of these candidate genes elucidated a catabolic pathway composed of four required gene products and several partially redundant dehydrogenases that convert DC-A to aromatic monomers that can be funneled into the central aromatic metabolic pathway of N. aromaticivorans . Specifically, a newly identified γ-formaldehyde lyase, PcfL, opens the phenylcoumaran ring to form a stilbene and formaldehyde. A lignostilbene dioxygenase, LsdD, then cleaves the stilbene to generate the aromatic monomers vanillin and 5-formylferulate (5-FF). We also showed that the aldehyde dehydrogenase FerD oxidizes 5-FF before it is decarboxylated by LigW, yielding ferulic acid. We found that some enzymes involved in the β-5 catabolism pathway can act on multiple substrates and that some steps in the pathway can be mediated by multiple enzymes, providing new insights into the robust flexibility of aromatic catabolism in N. aromaticivorans . A comparative genomic analysis predicted that the newly discovered β-5 aromatic catabolic pathway is common within the order Sphingomonadales. IMPORTANCE In the transition to a circular bioeconomy, the plant polymer lignin holds promise as a renewable source of industrially important aromatic chemicals. However, since lignin contains aromatic subunits joined by various chemical linkages, producing single chemical products from this polymer can be challenging. One strategy to overcome this challenge is using microbes to funnel a mixture of lignin-derived aromatics into target chemical products. This approach requires strategies to cleave the major inter-unit linkages of lignin to release monomers for funneling into valuable products. In this study, we report newly discovered aspects of a pathway by which the Novosphingobium aromaticivorans DSM12444 catabolizes aromatics joined by the second most common inter-unit linkage in lignin, the β-5 linkage. This work advances our knowledge of aromatic catabolic pathways, laying the groundwork for future metabolic engineering of this and other microbes for optimized conversion of lignin into products.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2014

A roadmap to uranium ionic liquids: Anti-crystal engineering

In the search for uranium-based ionic liquids, tris(N,N-dialkyldithiocarbamato)uranylates have been synthesized as salts of the 1-butyl-3-methylimidazolium (C 4 mim) cation. As dithiocarbamate ligands binding to the UO 2 2+ unit, tetra-, penta-, hexa-, and heptamethylenedithiocarbamates, N,N-diethyldithiocarbamate, N-methyl-N-propyldithiocarbamate, N-ethyl-N-propyldithiocarbamate, and N-methyl-N-butyldithiocarbamate have been explored. X-ray single-crystal diffraction allowed unambiguous structural characterization of all compounds except N-methyl-N-butyldithiocarbamate, which is obtained as a glassy material only. In addition, powder X-ray diffraction as well as vibrational and UV/Vis spectroscopy, supported by computational methods, were used to characterize the products. Differential scanning calorimetry was employed to investigate the phase-transition behavior depending on the N,N-dialkyldithiocarbamato ligand with the aim to establish structure–property relationships regarding the ionic liquid formation capability. Compounds with the least symmetric N,N-dialkyldithiocarbamato ligand and hence the least symmetric anions, tris(N-methyl-N-propyldithiocarbamato)uranylate, tris(N-ethyl-N-propyldithiocarbamato)uranylate, and tris(N-methyl-N-butyldithiocarbamato)uranylate, lead to the formation of (room-temperature) ionic liquids, which confirms that low-symmetry ions are indeed suitable to suppress crystallization. As a result, these materials combine low melting points, stable complex formation, and hydrophobicity and are therefore excellent candidates for nuclear fuel purification and recovery.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Lactobacillus casei as a biocatalyst for biofuel production

Abstract Microbial fermentation of sugars from plant biomass to alcohols represents an alternative to petroleum-based fuels. The optimal biocatalyst for such fermentations needs to overcome hurdles such as high concentrations of alcohols and toxic compounds. Lactic acid bacteria, especially lactobacilli, have high innate alcohol tolerance and are remarkably adaptive to harsh environments. This study assessed the potential of five Lactobacillus casei strains as biocatalysts for alcohol production. L. casei 12A was selected based upon its innate alcohol tolerance, high transformation efficiency and ability to utilize plant-derived carbohydrates. A 12A derivative engineered to produce ethanol (L. casei E1) was compared to two other bacterial biocatalysts. Maximal growth rate, maximal optical density and ethanol production were determined under conditions similar to those present during alcohol production from lignocellulosic feedstocks. L. casei E1 exhibited higher innate alcohol tolerance, better growth in the presence of corn stover hydrolysate stressors, and resulted in higher ethanol yields.

Vinay-Lara, Elena↗