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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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All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Catalytic deconstruction of organic additive-containing plastics

Plastics waste ends up in landfills, oceans, and incinerators, posing major environmental and human health threats. Catalytic deconstruction is emerging as a key technological solution to handle complex plastics and has successfully converted virgin polymers into various products. Here, we investigate the resilience of chemical deconstruction technologies to organic additives, which are ubiquitous in plastics. We study catalyst-additive interactions experimentally and via first-principles calculations for plastics additives representative of entire classes. We reveal two deactivation mechanisms and demonstrate that many recently developed catalysts are inadequate for polyolefin conversion due to poisoning caused by the strong adsorption of most additives or their small fragments. Furthermore, we also identify conditions and catalysts that can circumvent the challenge of deconstruction in the presence of additives challenge.

10 SYNTHETIC FUELS↗
NASA NTRS2003

High-Temperature Oxidation-Resistant and Low Coefficient of Thermal Expansion NiAl-Base Bond Coat Developed for a Turbine Blade Application

Many critical gas turbine engine components are currently made from Ni-base superalloys that are coated with a thermal barrier coating (TBC). The TBC consists of a ZrO2-based top coat and a bond coat that is used to enhance the bonding between the superalloy substrate and the top coat. MCrAlY alloys (CoCrAlY and NiCrAlY) are currently used as bond coats and are chosen for their very good oxidation resistance. TBC life is frequently limited by the oxidation resistance of the bond coat, along with a thermal expansion mismatch between the metallic bond coat and the ceramic top coat. The aim of this investigation at the NASA Glenn Research Center was to develop a new longer life, higher temperature bond coat by improving both the oxidation resistance and the thermal expansion characteristics of the bond coat. Nickel aluminide (NiAl) has excellent high-temperature oxidation resistance and can sustain a protective Al2O3 scale to longer times and higher temperatures in comparison to MCrAlY alloys. Cryomilling of NiAl results in aluminum nitride (AlN) formation that reduces the coefficient of thermal expansion (CTE) of the alloy and enhances creep strength. Thus, additions of cryomilled NiAl-AlN to CoCrAlY were examined as a potential bond coat. In this work, the composite alloy was investigated as a stand-alone substrate to demonstrate its feasibility prior to actual use as a coating. About 85 percent of prealloyed NiAl and 15 percent of standard commercial CoCrAlY alloys were mixed and cryomilled in an attritor with stainless steel balls used as grinding media. The milling was carried out in the presence of liquid nitrogen. The milled powder was consolidated by hot extrusion or by hot isostatic pressing. From the consolidated material, oxidation coupons, four-point bend, CTE, and tensile specimens were machined. The CTE measurements were made between room temperature and 1000 C in an argon atmosphere. It is shown that the CTE of the NiAl-AlN-CoCrAlY composite bond coat is lower than that of the commercially used coating alloy 16-6. To examine the potential of NiAl-AlN-CoCrAlY as a bond coat, we subjected two samples to cyclic furnace testing. The furnace cycle consisted of 45 min at 1163 C (2125 F ) followed by 15 min of cooling out of the furnace. The current NASA baseline TBC is a NiCrAlY bond coat below the 7YSZ top coat. The average TBC life for this baseline coating on Ren N5 is 188 plus or minus 19 cycles. NiAl-AlN-CoCrAlY specimens coated with the same 7YSZ top coat were still intact even after 1000 cycles. Therefore, the NiAl-AlN-CoCrAlY as a bulk substrate material, exhibits more than 5 times the life of the current state-of-the-art material. The next step is to evaluate this material as a coating on the same superalloy substrate.

Source record↗
NASA NTRS2008

Does NASA's Constellation Architecture Offer Opportunities to Achieve Multiple Additional Goals in Space?

Every major NASA human spaceflight program in the last four decades has been modified to achieve goals in space not incorporated within the original design goals: the Apollo Applications Program, Skylab, Space Shuttle, and International Space Station. Several groups in the US have been identifying major future science goals, the science facilities necessary to investigate them, as well as possible roles for augmented versions of elements of NASA's Constellation program. Specifically, teams in the astronomy community have been developing concepts for very capable missions to follow the James Webb Space Telescope that could take advantage of - or require - free-space operations by astronauts and/or robots. Taking as one example, the Single-Aperture Far-InfraRed (SAFIR) telescope with a approx. 10+ m aperture proposed for operation in the 2020 timeframe. According to current NASA plans, the Ares V launch vehicle (or a variant) will be available about the same time, as will the capability to transport astronauts to the vicinity of the Moon via the Orion Crew Exploration Vehicle and associated systems. [As the lunar surface offers no advantages - and major disadvantages - for most major optical systems, the expensive system for landing and operating on the lunar surface is not required.] Although as currently conceived, SAFIR and other astronomical missions will operate at the Sun-Earth L2 location, it appears trivial to travel for servicing to the more accessible Earth-Moon L1,2 locations. Moreover. as the recent Orbital Express and Automated Transfer Vehicle missions have demonstrated, future robotic capabilities should offer capabilities that would (remotely) extend human presence far beyond the vicinity of the Earth. In addition to multiplying the value of NASA's architecture for future human spaceflight to achieve the goals multiple major stakeholders. if humans one day travel beyond the Earth-Moon system - say, to Mars - technologies and capabilities for operating for long periods in free space must be developed. The engineering, management. and operational successes of the Space Station have demonstrated that international collaboratio~i is possible. However, there is a danger that the hard-won lessons of cLul+sent programs will be lost without continuing development of in-space operations. A program to achieve. for example. major astronomical goals in space using astronauts and robots will sustain international capabilities. produce highly visible achievements. and appeal to a11 additional broad community of stakeholders not currently involved with missions to the lunar surface.

Thronson, Harley↗
NASA NTRS1999

Airborne Radar Observations of Hurricane Georges during Landfall over the Dominican Republic

On 22 September 1998 hurricane Georges made landfall on the Dominican Republic (DR). Georges cost the DR at least 500 lives, made more than 155,000 people homeless and caused extensive damage to the country's main industries, tourism and agriculture. There was considerable wind damage, with wind gusts up to 58 m/s in Santa Domingo on the south coast, but most of the damage and deaths resulted from mudslides and the flooding of rivers. While this may have been the worst natural disaster to strike the DR, the sustained rapid storm movement saved the island from worse damage. Georges had previously affected several islands in the Lesser Antilles and Puerto Rico, but it had retained much of its circulation strength. Forty raingauge stations across the DR measured rainfall totals from Georges between 0.7 and 41 cm, the latter at the capital Santo Domingo, located on the south coast. At Herrera the maximum 1 h rainfall rate was 72 mm/h. It is suspected that much higher rain rates occurred in DR's mountainous interior. Before landfall the eye was clearly evident in satellite imagery. When the eye moved over southeastern DR, it filled rapidly, and the cloud top height decreased in all storm sectors except in the southern inflow sector, where a long-lived MCS, with a diameter larger than that of the eyewall, slowly became enwrapped in the hurricane circulation. The eye closure was most rapid between 16-18 UTC, when the eyewall circulation felt the mountainous terrain of the Cordillera Central, which rises up to 3,093 m. The estimated central pressure increased from 962 hPa at 15 UTC to 986 hPa at 03Z on 23 Sept, and the maximum sustained surface wind speed decreased from 54 to 36 in s-1 during the same period. The island of Hispaniola has a cross-track width of about 250 km, much wider than the diameter of the eyewall anvil (about 100 km before landfall). So the event can truly be considered to be a landfalling case, even though Georges recovered after crossing Hispaniola, albeit never to the same strength. This talk will summarize satellite and ground observations of Georges, as it passed the DR, and it will focus on EDOP data. In particular, we will try to estimate the rainfall rate over the mountainous terrain of the DR. And we will use detailed sounding data to explain the presence and characteristics of the massive MCS to the south, as well as the upper-level updrafts apparent over this MCS and over the mountains of the DR.

Geerts, B.↗
DOE OSTI2022

Molecular-Level Control over Ionic Conduction and Ionic Current Direction by Designing Macrocycle-Based Ionomers

Poor ionic conductivity of the catalyst-binding, submicrometer- thick ionomer layers in energy conversion and storage devices is a huge challenge. However, ionomers are rarely designed keeping in mind the specific issues associated with nanoconfinement. Here, we designed nature-inspired ionomers (calix-2) having hollow, macrocyclic, calix[4]arene-based repeat units with precise, sub-nanometer diameter. In ≤100 nm-thick films, the in-plane proton conductivity of calix-2 was up to 8 times higher than the current benchmark ionomer Nafion at 85% relative humidity (RH), while it was 1-2 orders of magnitude higher than Nafion at 20-25% RH. Confocal laser scanning microscopy and other synthetic techniques allowed us to demonstrate the role of macrocyclic cavities in boosting the proton conductivity. The systematic self-assembly of calix-2 chains into ellipsoids in thin films was evidenced from atomic force microscopy and grazing incidence small-angle X-ray scattering measurements. Moreover, the likelihood of alignment and stacking of macrocyclic units, the presence of one-dimensional water wires across this macrocycle stacks, and thus the formation of long-range proton conduction pathways were suggested by atomistic simulations. We not only did see an unprecedented improvement in thin-film proton conductivity but also saw an improvement in proton conductivity of bulk membranes when calix-2 was added to the Nafion matrices. Nafion-calix-2 composite membranes also took advantage of the asymmetric charge distribution across calix[4]arene repeat units collectively and exhibited voltage-gating behavior. The inclusion of molecular macrocyclic cavities into the ionomer chemical structure can thus emerge as a promising design concept for highly efficient ion-conducting and ion-permselective materials for sustainable energy applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Meta-omics reveals role of photosynthesis in microbially induced carbonate precipitation at a CO2-rich geyser

Abstract Microbially induced carbonate precipitation (MICP) is a natural process with potential biotechnological applications to address both carbon sequestration and sustainable construction needs. However, our understanding of the microbial processes involved in MICP is limited to a few well-researched pathways such as ureolytic hydrolysis. To expand our knowledge of MICP, we conducted an omics-based study on sedimentary communities from travertine around the CO2-driven Crystal Geyser near Green River, Utah. Using metagenomics and metaproteomics, we identified the community members and potential metabolic pathways involved in MICP. We found variations in microbial community composition between the two sites we sampled, but Rhodobacterales were consistently the most abundant order, including both chemoheterotrophs and anoxygenic phototrophs. We also identified several highly abundant genera of Cyanobacteriales. The dominance of these community members across both sites and the abundant presence of photosynthesis-related proteins suggest that photosynthesis could play a role in MICP at Crystal Geyser. We also found abundant bacterial proteins involved in phosphorous starvation response at both sites suggesting that P-limitation shapes both composition and function of the microbial community driving MICP.

Violette, Marlene J.↗
NASA NTRS2011

Dynamical States of Low Temperature Cirrus

Low ice crystal concentration and sustained in-cloud supersaturation, commonly found in cloud observations at low temperature, challenge our understanding of cirrus formation. Heterogeneous freezing from effloresced ammonium sulfate, glassy aerosol, dust and black carbon are proposed to cause these phenomena; this requires low updrafts for cirrus characteristics to agree with observations and is at odds with the gravity wave spectrum in the upper troposphere. Background temperature fluctuations however can establish a dynamical equilibrium between ice production and sedimentation loss (as opposed to ice crystal formation during the first stages of cloud evolution and subsequent slow cloud decay) that explains low temperature cirrus properties. This newly-discovered state is favored at low temperatures and does not require heterogeneous nucleation to occur (the presence of ice nuclei can however facilitate its onset). Our understanding of cirrus clouds and their role in anthropogenic climate change is reshaped, as the type of dynamical forcing will set these clouds in one of two preferred microphysical regimes with very different susceptibility to aerosol.

Barahona, D.↗
NASA NTRS2019

Observational Needs for Improving Ocean and Coupled Reanalysis, S2S Prediction, and Decadal Prediction

Developments in ocean data assimilation (DA) and observing system technologies are intertwined. New observation types lead to new DA methods, and new DA methods such as Coupled Data Assimilation can change the value of existing observations or indicate where new observations can have greater utility for monitoring and prediction. Practitioners are encouraged to make better use of observations that are already available, for example in strongly coupled data assimilation where ocean observations can be used to improve atmospheric analyses and vice versa. Ocean reanalyses are useful for the analysis of climate,as well as initializing operational long-range prediction models. There are remaining challenges for ocean reanalyses due to biases and abrupt changes in the ocean observing system throughout its history, the presence of biases and drifts in models, and simplifying assumptions made in the DA methods. From a governance point of view, more support is needed to interface the observing community and the ocean DA community. For prediction applications, the ocean DA community must work with the ocean observing community to establish protocols for rapid communication of ocean observing data on NWP timescales. There is potential for new observations to enhance the observing system by supporting prediction on multiple timescales, ranging from the typical timescale of numerical weather prediction covering hours to weeks, out to multiple decades. It is highly encouraged that communication be fostered between thesecommunities to allow operational prediction centers the ability to provide guidance to the design of a sustained and adaptive observing network.

Ocean reanalysis↗
DOE OSTI2022

A novel sub-pilot-scale direct-contact ultrasonic dehydration technology for sustainable production of distillers dried grains (DDG)

DDG is a major source of protein, calcium, phosphorus, and sulfur is arguably the most important byproduct of the bioethanol industry with increasing demand over the past few years. Reducing energy consumption in the DDG production process and energy recovery from DDG is vital for sustainable bioethanol productions. In this paper, a novel direct-contact multi-frequency, multimode, and modulated (MMM) ultrasonic dryer (US) was developed for the first time and has been applied in dehydration of wet distillers' grain (WDG). Ultrasonic drying (US) was combined with a convective airflow (HA) at different temperatures of 25 (room temperature), 50 and 70 °C to evaluate the impact of US, HA, and US + HA on drying kinetics, activation energy, chemical compositions, microstructure, and color of DDG. Semi-empirical kinetic models were developed and evaluating drying performances showed that the application of ultrasound significantly enhanced the drying rate and decreased the drying time (by 46%), especially at low drying temperatures. The activation energy for moisture removal in the presence of ultrasound was about 50% of that without ultrasound. The final dried distillers' grains product processed by ultrasonic drying had a brighter color, a higher available protein, a higher digestible protein (the lowest acid detergent insoluble crude protein), and a better surface profile with no compromise on minerals and fiber contents.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Penta-SiCN: A Highly Auxetic Monolayer

We report the negative Poisson’s (NPR) ratio in a two-dimensional (2D) material is a counterintuitive mechanical property that facilitates the development of nanoscale devices with sophisticated functionality. Inspired by the peculiar buckled lower-symmetric, trilayered geometry of pentagonal monolayers, we theoretically predict penta-SiCN, a ternary auxetic metallic monolayer with highly tunable NPR. The penta-SiCN is structurally, thermally, dynamically, and mechanically stable, and sustainable at and beyond room temperature with experimental feasibility. It possesses nontrivial geometrical and mechanical isotropy and relatively moderate thickness. Remarkably, the shorter and quasi sp3-hybridized C–N bond and the rigidity against the strain allow the monolayer to possess a high value of NPR (-0.136), even higher than that of black phosphorene, extendable up to -0.639 by 4% of biaxial stretching. On the other hand, the 2D Young’s modulus of 129.88 N/m decreases to 41.34 N/m at equivalent stretching, indicating relative softening and flexibility. Interestingly, a buckled-to-planar phase transition is identified at 10% biaxial strain before it suffers the fracture at 16%. Additionally, the strong optical anisotropy, absorbance (up to 6.51 x 105 cm -1 ), and presence of plasmon frequency demonstrate its potential application in optomechanical and plasmonics.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Fighting the climate crisis with caloric heat pumping: Innovations to enable widespread adoption

Caloric heat pumping is a cross-cutting thermal energy technology that can cover a wide range of applications and temperatures, from millikelvins to hundreds of kelvins, with a working medium that has zero global warming potential. The technology promises cost savings and high efficiency, having 60% Carnot efficiency demonstrated to date. The Energy Earthshots™ Initiative, launched by the U.S. Department of Energy, aims to fight the climate crisis and overcome technological barriers to a decarbonized economy. The initiative focuses on the development of energy solutions that increase efficiency, reduce greenhouse gas emissions, and ensure affordability. Three out of eight Energy Earthshots™ look for alternative thermal energy technologies for extensive temperature ranges, from hydrogen liquefaction to metal-treating temperatures. Caloric heat pumping can fulfill all these requirements; however, at the current stage, caloric systems have limited presence in real-world applications. Further, this perspective discusses key efforts to address barriers hindering the widespread adoption of caloric technology. We focus on essential breakthroughs in and effective approaches to material discovery and draw a path to high-power-density, grid-interactive caloric systems to support achieving the ambitious net-zero carbon economy goal.

42 ENGINEERING↗
DOE OSTI2022

Detecting Cage Crossing and Filling Clusters of Magnesium and Carbon Atoms in Zeolite SSZ-13 with Atom Probe Tomography

The conversion of methanol to valuable hydrocarbon molecules is of great commercial interest, as the process serves as a sustainable alternative for the production of, for instance, the base chemicals for plastics. The reaction is catalyzed by zeolite materials. By the introduction of magnesium as a cationic metal, the properties of the zeolite, and thereby the catalytic performance, are changed. With atom probe tomography (APT), nanoscale relations within zeolite materials can be revealed: i.e., crucial information for a fundamental mechanistic understanding. We show that magnesium forms clusters within the cages of zeolite SSZ-13, while the framework elements are homogeneously distributed. These clusters of just a few nanometers were analyzed and visualized in 3-D. Magnesium atoms seem to initially be directed to the aluminum sites, after which they aggregate and fill one or two cages in the zeolite SSZ-13 structure. The presence of magnesium in zeolite SSZ-13 increases the lifetime as well as the propylene selectivity. By using operando UV–vis spectroscopy and X-ray diffraction techniques, we are able to show that these findings are related to the suppression of aromatic intermediate products, while maintaining the formation of polyaromatic compounds. Further nanoscale analysis of the spent catalysts showed indications of magnesium redistribution after catalysis. Unlike zeolite H-SSZ-13, for which only a homogeneous distribution of carbon was found, carbon can be either homogeneously or heterogeneously distributed within zeolite Mg-SSZ-13 crystals as the magnesium decreases the coking rate. Carbon clusters were isolated, visualized, and analyzed and were assumed to be polyaromatic compounds. Small one-cage-filling polyaromatic compounds were identified; furthermore, large-cage-crossing aromatic molecules were found by isolating large coke clusters, demonstrating the unique coking mechanism in zeolite SSZ-13. Short-length-scale evidence for the formation of polyaromatic compounds at acid sites is discovered, as clear nanoscale relations between aluminum and carbon atoms exist.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Photocatalytic Semiconductor–Metal Hybrid Nanoparticles: Single-Atom Catalyst Regime Surpasses Metal Tips

Semiconductor–metal hybrid nanoparticles (HNPs) are promising materials for photocatalytic applications, such as water splitting for green hydrogen generation. While most studies have focused on Cd containing HNPs, the realization of actual applications will require environmentally compatible systems. Using heavy-metal free ZnSe-Au HNPs as a model, we investigate the dependence of their functionality and efficiency on the cocatalyst metal domain characteristics ranging from the single-atom catalyst (SAC) regime to metal-tipped systems. The SAC regime was achieved via the deposition of individual atomic cocatalysts on the semiconductor nanocrystals in solution. Utilizing a combination of electron microscopy, X-ray absorption spectroscopy, and X-ray photoelectron spectroscopy, we established the presence of single Au atoms on the ZnSe nanorod surface. Upon increased Au concentration, this transitions to metal tip growth. Photocatalytic hydrogen generation measurements reveal a strong dependence on the cocatalyst loading with a sharp response maximum in the SAC regime. Ultrafast dynamics studies show similar electron decay kinetics for the pristine ZnSe nanorods and the ZnSe-Au HNPs in either SAC or tipped systems. This indicates that electron transfer is not the rate-limiting step for the photocatalytic process. Combined with the structural-chemical characterization, we conclude that the enhanced photocatalytic activity is due to the higher reactivity of the single-atom sites. This holistic view establishes the significance of SAC-HNPs, setting the stage for designing efficient and sustainable heavy-metal-free photocatalyst nanoparticles for numerous applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Stochasticity in microbiology: managing unpredictability to reach the Sustainable Development Goals

Pure (single) cultures of microorganisms and mixed microbial communities (microbiomes) have been important for centuries in providing renewable energy, clean water and food products to human society and will continue to play a crucial role to pursue the Sustainable Development Goals. To use microorganisms effectively, microbial engineered processes require adequate control. Microbial communities are shaped by manageable deterministic processes, but also by stochastic processes, which can promote unforeseeable variations and adaptations. Here, we highlight the impact of stochasticity in single culture and microbiome engineering. First, we discuss the concepts and mechanisms of stochasticity in relation to microbial ecology of single cultures and microbiomes. Second, we discuss the consequences of stochasticity in relation to process performance and human health, which are reflected in key disadvantages and important opportunities. Third, we propose a suitable decision tool to deal with stochasticity in which monitoring of stochasticity and setting the boundaries of stochasticity by regulators are central aspects. Stochasticity may give rise to some risks, such as the presence of pathogens in microbiomes. We argue here that by taking the necessary precautions and through clever monitoring and interpretation, these risks can be mitigated.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

A Molecular Compound for Highly Selective Purification of Ethylene

Purification of C 2 H 4 from an C 2 H 4 /C 2 H 6 mixture is one of the most challenging separation processes, which is achieved mainly through energy-intensive, cryogenic distillation in industry. Sustainable, non-distillation methods are highly desired as alternatives. We discovered that the fluorinated bis(pyrazolyl)borate ligand supported copper(I) complex {[(CF 3 ) 2 Bp]Cu} 3 has features very desirable in an olefin–paraffin separation material. It binds ethylene exclusively over ethane generating [(CF 3 ) 2 Bp]Cu(C 2 H 4 ). This molecular compound exhibits extremely high and record ideal adsorbed solution theory (IAST) C 2 H 4 /C 2 H 6 gas separation selectivity, affording high purity (>99.5 %) ethylene that can be readily desorbed from separation columns. In-situ PXRD provides a “live” picture of the reversible conversion between [(CF 3 ) 2 Bp]Cu(C 2 H 4 ) and the ethylene-free sorbent in the solid-state, driven by the presence or removal of C 2 H 4 . As a result, molecular structures of trinuclear {[(CF 3 ) 2 Bp]Cu} 3 and mononuclear [(CF 3 ) 2 Bp]Cu(C 2 H 4 ) are also presented.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

A simultaneous depolymerization and hydrodeoxygenation process to produce lignin-based jet fuel in continuous flow reactor

Economical production of lignin-based jet fuel (LJF) can improve the sustainability of sustainable aviation fuels (SAFs) as well as can reduce the overall greenhouse gas emissions. However, the challenge lies in converting technical lignin polymer from biorefinery directly to jet fuel in a continuous operation. In this work, we demonstrate a simultaneous depolymerization and hydrodeoxygenation (SDHDO) process to produce lignin-based jet fuel from the alkali corn stover lignin (ACSL) using engineered Ru-HY-60-MI catalyst in a continuous flow reactor at first time. The maximum carbon yield of LJF of 17.9wt% was obtained, and it comprised of 60.2wt% monocycloalkanes, and 21.6wt% polycycloalkanes. Catalyst characterization of Ru-HY-60-MI suggested there was no significant change in HY zeolite structure and its crystallinity after catalyst engineering. Catalyst characterizations performed post the SDHDO experiments indicate presence of carbon and K content in the catalyst. K content presence in the spent catalyst was due to K + ion was exchanged between lignin solution and HY-60 while carbon presence validated the SDHDO chemistry on the catalyst surface. Tier a fuel property testing indicates that LJF production using SDHDO chemistry can offer SAF with high compatibility, good sealing properties, low emissions, and high energy density for aircraft.

09 BIOMASS FUELS↗
DOE OSTI2025

Bioconversion of self-neutralized chemically depolymerized lignin streams into polyhydroxyalkanoates

Lignin is a chemically complex, diverse, and abundant plant polymer mainly composed of aromatic monomers. These aromatic monomers make lignin a potential source of aromatics and a viable substitute for petrochemically-derived aromatics. However, the structural recalcitrance of lignin requires harsh reagents from the chemical process and expensive catalysts for effective depolymerization. This chemical process often results in poor yields of chemical intermediate mixtures of varying bioavailability and/or toxicity. Furthermore, the cost of additional reagents required to separate or detoxify these intermediates makes processing lignin impractical. We report progress towards the use of such chemically depolymerized lignin streams by employing bacterial strains to produce polyhydroxyalkanoates (PHA). PHAs are a group of biodegradable microbial polyesters that have potential as a replacement for petroleum-based plastics. In this study we utilized two distinct lignin streams obtained after chemical depolymerization of lignin under alkaline and acidic pH in the presence of catalysts. We mixed the alkali-treated depolymerized stream with the acid-treated depolymerized stream to create a solution of neutral-pH chemically depolymerized lignin (CDL). We found moderate to substantial growth of both native and non-native PHA producers on the mixture of CDL as well as its aliphatic and aromatic components. PHA was detected by Sudan Black B staining in C. necator H16, P. putida KT2440, and E. coli LSBJ STQKAB grown on mixed CDL as the sole carbon source. For C. necator H16 and E. coli LSBJ STQKAB we found that PHA content was greater when grown on mixed CDL when compared to their preferred carbon source by GC-FID quantification. Our study provided progress towards a cost-competitive, sustainable, and industrially relevant use for lignin.

Winkler, Gordon L. W. [Univ. of Wisconsin, Madison↗
NASA NTRS2015

Development of Additive Construction Technologies for Application to Development of Lunar/Martian Surface Structures Using In-Situ Materials

For long-duration missions on other planetary bodies, the use of in situ materials will become increasingly critical. As human presence on these bodies expands, so must the breadth of the structures required to accommodate them including habitats, laboratories, berms, radiation shielding for natural radiation and surface reactors, garages, solar storm shelters, greenhouses, etc. Planetary surface structure manufacturing and assembly technologies that incorporate in situ resources provide options for autonomous, affordable, pre-positioned environments with radiation shielding features and protection from micrometeorites, exhaust plume debris, and other hazards. The ability to use in-situ materials to construct these structures will provide a benefit in the reduction of up-mass that would otherwise make long-term Moon or Mars structures cost prohibitive. The ability to fabricate structures in situ brings with it the ability to repair these structures, which allows for the self-sufficiency and sustainability necessary for long-duration habitation. Previously, under the auspices of the MSFC In-Situ Fabrication and Repair (ISFR) project and more recently, under the jointly-managed MSFC/KSC Additive Construction with Mobile Emplacement (ACME) project, the MSFC Surface Structures Group has been developing materials and construction technologies to support future planetary habitats with in-situ resources. One such additive construction technology is known as Contour Crafting. This paper presents the results to date of these efforts, including development of novel nozzle concepts for advanced layer deposition using this process. Conceived initially for rapid development of cementitious structures on Earth, it also lends itself exceptionally well to the automated fabrication of planetary surface structures using minimally processed regolith as aggregate, and binders developed from in situ materials as well. This process has been used successfully in the fabrication of construction elements using lunar regolith simulant and Mars regolith simulant, both with various binder materials. Future planned activities will be discussed as well.

Werkheiser, Niki J.↗