Regional distributions of efferent neurons in the semicircular canals in the gerbil
No abstract available
NASA Discipline Neuroscience↗
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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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CO2U Example Report: NETL CO2 to Renewable Diesel and Co-products via Algal Production
This report represents an example of a completed project for the CO2 Utilization program. The LCA for this example corresponds to the example product systems in the NETL openLCA Life Cycle Inventory (LCI) database. This example LCA represents a fictional microalgae-to-biofuel, hereafter called algae-to-biofuel, technology pathway.
Krynock, Michelle↗
Thermochemical Conversion of Woody Biomass to Fuels and Chemicals Final Report
Maine and its industries identified more efficient utilization of biomass as a critical economic development issue. In Phase I of this implementation project, a research team was assembled, research equipment was implemented and expertise was demonstrated in pyrolysis, hydrodeoxygenation of pyrolysis oils, catalyst synthesis and characterization, and reaction engineering. Phase II built upon the infrastructure to innovate reaction pathways and process engineering, and integrate new approaches for fuels and chemical production within pulp and paper and other industries within the state. This research cluster brought together chemists, engineers, physicists and students from the University of Maine, Bates College, and Bowdoin College. The project developed collaborations with Oak Ridge National Laboratory and Brookhaven National Laboratory. The specific research projects within this proposal were of critical interest to the DoE - in particular the biomass program within EERE and the catalysis/chemical transformations program within BES. Scientific and Technical Merit highlights of this project included: (1) synthesis and physical characterization of novel size-selective catalyst/supports using engineered mesoporous (1-10 nm diameter pores) materials, (2) advances in fundamental knowledge of novel support/ metal catalyst systems tailored for pyrolysis oil upgrading, (3) a microcalorimetric sensing technique, (4) improved methods for pyrolysis oil characterization, (5) production and characterization of woody biomass-derived pyrolysis oils, (6) development of two new patented bio oil pathways: thermal deoxygenation (TDO) and formate assisted pyrolysis (FASP), and (7) technoeconomics of pyrolysis of Maine forest biomass. This research cluster has provided fundamental knowledge to enable and assess pathways to thermally convert biomass to hydrocarbon fuels and chemicals.
09 BIOMASS FUELS↗
Wilson Corners Solid Waste Management Unit (SWMU) 001: 2021 Annual Long-Term Monitoring Report, Kennedy Space Center, Florida
This report presents a summary of the long-term monitoring (LTM) activities that occurred in 2021 at Wilson Corners, Solid Waste Management Unit (SWMU) 001, at Kennedy Space Center (KSC), Florida. The site is monitored under KSC’s Resource Conservation and Recovery Act (RCRA) Corrective Action Program. Adaptive site management is being utilized through ongoing assessment, design, and interim measures (IM). Annual LTM of the groundwater is also being conducted at the site. This approach also meets the requirements of Chapter 62-780, Florida Administrative Code (F.A.C.). The goal of LTM at this site is threefold: to determine groundwater flow characteristics, monitor the downgradient concentration trends, and monitor select locations internal to the groundwater plume. Every 5 years, upgradient and side-gradient monitoring wells are sampled to verify delineation. The last time this was performed was in 2015. The sampling of these wells in 2020 was replaced with the direct push technology (DPT) investigations completed in October 2020 and April 2021. This DPT groundwater data was presented in an Advance Data Package (ADP) in September 2021 and discussed in the Implementation Work Plan (IWP) dated November 2021 for installation of an air sparge (AS) system. Based on results from groundwater sampling activities performed during the previous reporting period, including the 2020 and 2021 DPT groundwater sampling, it was determined that the LTM sampling plan was no longer meeting the goal of LTM because delineation was not verified. The 2021 LTM sampling plan was modified to include the sampling of monitoring wells located around the perimeter of the low concentration plume (LCP); the area with concentrations of contaminants of concern [COCs] greater than Groundwater Cleanup Target Levels [GCTLs]), and sampling of 10 monitoring wells proposed for installation (April 2021 KSC Remediation Team (KSCRT) Meeting, Decision 2104-D32). The modified LTM plan received team consensus at the September 2021 KSCRT Meeting (Decision Number 2109-D03), and sampling of the existing monitoring wells was completed in December 2021. The proposed monitoring wells are planned for installation in late 2022, concurrent with ongoing IM construction activities. December 2021 LTM data was presented at the May 2022 KSCRT Meeting, and activities are summarized in this report. The activities presented in this report include the December 2021 groundwater gauging of 42 monitoring wells and sampling of 44 monitoring wells. During the December 2021 event, the low flow sampling method was used, and samples were analyzed for a select list of volatile organic compounds (VOCs), including 1,1,2-trichloro-1,2,2-trifluoroethane (Freon 113). The following conclusions can be made based on the 2021 LTM results: - In December 2021, groundwater flow for the site was generally to the west at all intervals. This is generally consistent with historical observations at the site, with the exception of a southwest and southeast flow component observed at 34 to 48 feet below land surface (bls). - The vertical extent of VOCs was historically delineated by monitoring wells screened greater than 48 feet bls. The results from the two vertical extent monitoring wells, WILC-MW0078 (screened 65 to 70 feet bls) and WILC-MW0130 (screened 56 to 66 feet bls) that were sampled during the 2021 LTM indicate that groundwater vinyl chloride (VC) concentrations in both wells were greater than the GCTL. The Remediation Team has previously agreed to delay deeper DPT investigations in this area to prevent the creation of additional pathways for vertical migration. - The LCP continues to extend both horizontally, predominantly to the west, and vertically beyond the current monitoring well network, with some retraction observed to the southeast. Evaluation of this data combined with data from the 2020 and 2021 DPT sampling event indicate that the LCP encompasses an estimated 20.7 acres based on an expanded sampling area, as compared to the 2020 LCP footprint of 17.0 acres. - Freon 113 was not detected above GCTLs during the 2021 LTM event. Based on groundwater sampling activities performed in 2021, including April 2021 DPT groundwater sampling, the following recommendations are provided: - Perform the next LTM sampling event, targeted to occur in 2023, concurrently with the IM baseline sampling prior to AS system installation; - Include sampling from nine monitoring wells that are planned to be installed in late 2022, concurrent with upcoming IM construction activities. Installation of one deep vertical well, screened 70 to 80 feet bls, will be delayed to prevent the creation of an additional pathway for vertical migration; - Continue to sample under the modified annual LTM plan as presented in Table 4-1 concurrently with IM baseline sampling; and - Once the AS system install and start-up is complete, select monitoring wells from the LTM program will transition into the performance monitoring plan, and LTM will be temporarily discontinued. Performance monitoring will be performed quarterly, and the monitoring well network will be evaluated following the first performance monitoring sampling event.
long-term monitoring (LTM)↗
Poster and Slide: Energy Loss: Exploring Dissipation Pathways from Ions to In-reactor
Young Researcher Association is hosting an early career poster and networking session on July 25th, 2019. The poster session is designed to provide an overview of the researcher’s experience prior to employment at INL, and their current area of research and interests. The following is a brief description of the major sections of the poster. Before starting at INL in May of this year, my research focused on exploring the effects of electronic and nuclear energy loss on the damage evolution of Ti3SiC2 MAX phase during energetic irradiations. A series of ion irradiations revealed a threshold in electronic energy loss (Se), above which the formation of a FCC-MAX structure is enhanced, accommodating point defects and alleviating lattice strain. However, systematically separating the effects reveals that increasing Se/Sn suppresses this phase formation, thus allowing the strain from point defects to increase and saturate. Presently my research supports Post Irradiation Examination (PIE) of U-Mo fuel for the USHPRR and KJRR programs. The PIE evaluation currently consists of non-destructive examination (NDE) of fuel plates irradiated in the Advanced Test Reactor (ATR), focusing on plate profilometry and fuel swelling analysis. NDE will culminate in finalizing the destructive examination (DE) test plans and execution of said DE. Additionally, I am interested in exploring the roles that different energy dissipation pathways play in the damage evolution of the U-Mo fuel, exploring the mechanisms by which the fuel remains in its meta-stable phase under irradiation at high temperatures.
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
Pathways to formulate lightweight and ultra-lightweight 3D printable cementitious composites
Here, this paper studies the pathways to formulate lightweight and ultra-lightweight 3D printable cementitious composites. A hybrid approach was proposed by combining the advantages of traditional chemical-induced foaming (foaming approach) and lightweight particulate inclusions (synthetic foam approach). A comprehensive experimental program was conducted to evaluate the effects of foaming agents and fly ash cenosphere (FAC) on the printability, microstructure, mechanical and thermal properties of 3D printed samples. The results showed that the hybrid approach could produce a mixture with a density as low as 470 kg/m 3 while ensuring good flowability and buildability owing to the lubricating effect of foaming and supporting skeleton formed by FAC. In addition, a three-step homogenization procedure was also developed to predict the effective elastic modulus and thermal conductivity of 3D printable cementitious composites and cementitious foam. The findings of the study highlighted the effectiveness of the hybrid approach in formulating 3D printable ultra-lightweight cementitious composites in thermal insulation and acoustic applications.
36 MATERIALS SCIENCE↗
Numerical Model Development of a Variable-Geometry Attenuator Wave Energy Converter
Because the wave energy industry is still in its infancy, an optimal design for wave energy converters (WECs) has yet to be established; more work is needed to explore various cost-reduction pathways. The primary cost-reduction pathway considered for this work is the optimization of the geometric profile on an attenuator WEC to maximize power production while, at the same time, minimizing capital expenditures through the use of variable-geometry modules. In this investigation, the variable-geometry modules consist of inflatable bags placed on either side of a base central steel cylinder that would be inflated in low-moderate sea states to maximize power capture and then deflated in moderate-extreme sea states to minimize wave loading. The numerical model and simulation of the attenuator WEC were developed and completed using WEC-Sim, which is an open-source code that is appropriate for use in evaluating the dynamic response of the different WEC models in operational seas. The power production estimates were obtained from the Wave Energy Prize (WEP) sea states, which are representative of U. S. deployment sites, to calculate the average climate capture width that is used in the WEP ACE calculation. Preliminary capital expenditure costs were obtained assuming the base central steel cylinder mass was equal to the fluid displaced mass, minus the mass of the variable-geometry bags. The additional weight required to offset the additional buoyancy from the variable-geometry bags was assumed to come from the addition of seawater ballast. The variable-geometry attenuator model was found to have a similar power capture efficiency as a fixed-body model, but is expected to have a lower characteristic capital expenditure given its more streamlined profile, which demonstrates that variable-geometry modules may provide a realistic cost-reduction pathway to help design a more cost-competitive WEC.
50 EE - Wind and Water Power Program - Water (EE-4↗
Test Plan for the Horizontal Dry Cask Simulator
The thermal performance of commercial spent nuclear fuel dry storage casks is evaluated through detailed numerical analysis. These modeling efforts are completed by the vendor to demonstrate performance and regulatory compliance. The calculations are then independently verified by the Nuclear Regulatory Commission(NRC). Canistered dry storage cask systems rely on ventilation between the inner canister and the overpack to convect heat away from the canister to the surrounding environment for both horizontal and vertical configurations. Recent advances in dry storage cask designs have significantly increased the maximum thermal load allowed in a cask in part by increasing the efficiency of internal conduction pathways and by increasing the internal convection through greater canister helium pressure. Carefully measured data sets generated from testing of full sized casks or smaller cask analogs are widely recognized as vital for validating these models. While several testing programs have been previously conducted, these earlier validation studies did not integrate all the physics or components important in a modern, horizontal dry cask system. The purpose of the investigation described in this test plan is to produce data sets that can be used to benchmark the codes and best practices presently used to determine cladding temperatures and induced cooling air flows in modern horizontal dry storage systems. The horizontal dry cask simulator(HDCS) has been designed to generate this benchmark data and add to the existing knowledgebase. The pressure vessel representing the canister has been designed, fabricated, and pressure tested for a maximum allowable pressure(MAWP)rating of 2,400 kPa at400 °C. An existing electrically heated but otherwise prototypic boiling water reactor(BWR), Incoloy-clad test assembly will be deployed inside of a representative storage basket and canister. An insulated sheet metal enclosure will be used to mimic the thermal properties of the concrete vault enclosure used in a modern horizontal storage system. Radial and axial temperature profiles along with induced cooling air flow will be measured for a wide range of decay powers and representative(and higher)cask pressures using various backfills of helium, argon, or air. The single assembly geometry with well-controlled boundary conditions simplifies computational requirements while preserving relevant physics. The proposed test apparatus integrates all the underlying thermal-hydraulics important to defining the performance of a modern horizontal storage system. These include combined-mode heat transfer from the electrically-heated assembly to the canister walls and the primarily natural-convective heat transfer from the canister to the cooling air flow passing through the horizontal vault enclosure. The objective of the HDCS is not to reproduce the performance of a commercial dry storage system for any given set of operational parameters. Rather ,the objective is to capture the dominant physics in a well-characterized test apparatus. The close coupling between the thermal response of the canister system and the resulting induced cooling air flow rate is of particular importance. While incorporating the best available information based on thermal-hydraulic scaling arguments as well as previous vertical testing, this test plan is subject to changes due to improved understanding or from as built deviations to designs. As-built conditions and actual procedures will be documented in the final test report.
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
Development Challenges of Game-Changing Entry System Technologies From Concept to Mission Infusion
NASA's Space Technology Mission Directorate (STMD) and the Game Changing Development Program (GCDP) were created to develop new technologies. This paper describes four entry system technologies that are funded by the GCDP and summarizes the lessons learned during the development. The investments are already beginning to show success, mission infusion pathways after five years of existence. It is hoped that our experience and observations, drawn from projects supported by the GCD program/STMD, Orion and SMD can help current and future technology development projects. Observations on fostering a culture of success and on constraints that limit greater success are also provided.
Entry↗
Numerical Model Development of a Variable-Geometry Attenuator Wave Energy Converter: Preprint
Because the wave energy industry is still in its infancy, an optimal design for wave energy converters (WECs) has yet to be established; more work is needed to explore various cost reduction pathways. The primary cost-reduction pathway considered for this work is the optimization of the geometric profile on an attenuator WEC to maximize power production while, at the same time, minimizing capital expenditures through the use of variable-geometry modules. In this investigation, the variable geometry modules consist of inflatable bags placed on either side of a base central steel cylinder that would be inflated in low moderate sea states to maximize power capture and then deflated in moderate-extreme sea states to minimize wave loading. The numerical model and simulation of the attenuator WEC were developed and completed using WEC-Sim, which is an open-source code that is appropriate for use in evaluating the dynamic response of the different WEC models in operational seas. The power production estimates were obtained from the Wave Energy Prize (WEP) sea states, which are representative of U. S. deployment sites, to calculate the average climate capture width that is used in the WEP ACE calculation. Preliminary capital expenditure costs were obtained assuming the base central steel cylinder mass was equal to the fluid displaced mass, minus the mass of the variable-geometry bags. The additional weight required to offset the additional buoyancy from the variable-geometry bags was assumed to come from the addition of seawater ballast. The variable-geometry attenuator model was found to have a similar power capture efficiency as a fixed-body model, but is expected to have a lower characteristic capital expenditure given its more streamlined profile, which demonstrates that variable-geometry modules may provide a realistic cost-reduction pathway to help design a more cost-competitive WEC.
50 EE - Wind and Water Power Program - Water (EE-4↗
Snowmass Instrumentation Frontier IF08 Topical Group Report: Noble Element Detectors
Particle detectors making use of noble elements in gaseous, liquid, or solid phases are prevalent in neutrino and dark matter experiments and are also used to a lesser extent in collider-based particle physics experiments. These experiments take advantage of both the very large, ultra-pure target volumes achievable and the multiple observable signal pathways possible in noble-element based particle detectors. As these experiments seek to increase their sensitivity, novel and improved technologies will be needed to enhance the precision of their measurements and to broaden the reach of their physics programs. The areas of R&D in noble element instrumentation that have been identified by the HEP community in the Snowmass process are highlighted by five key messages: IF08-1) Enhance and combine existing modalities (scintillation and electron drift) to increase signal-to-noise and reconstruction fidelity; IF08-2) Develop new modalities for signal detection in noble elements, including methods based on ion drift, metastable fluids, solid-phase detectors and dissolved targets. Collaborative and blue-sky R&D should also be supported to enable advances in this area; IF08-3) Improve the understanding of detector microphysics and calibrate detector response in new signal regimes; IF08-4) Address challenges in scaling technologies, including material purification, background mitigation, large-area readout, and magnetization; and IF08-5) Train the next generation of researchers, using fast-turnaround instrumentation projects to provide the design-through-result training no longer possible in very-large-scale experiments. This topical group report identifies and documents recent developments and future needs for noble element detector technologies. In addition, we highlight the opportunity that this area of research provides for continued training of the next generation of scientists.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
Prenatal ethanol exposure programs an increased susceptibility of non-alcoholic fatty liver disease in female adult offspring rats
Prenatal ethanol exposure (PEE) induces dyslipidemia and hyperglycemia in fetus and adult offspring. However, whether PEE increases the susceptibility to non-alcoholic fatty liver disease (NAFLD) in offspring and its underlying mechanism remain unknown. This study aimed to demonstrate an increased susceptibility to high-fat diet (HFD)-induced NAFLD and its intrauterine programming mechanisms in female rat offspring with PEE. Rat model of intrauterine growth retardation (IUGR) was established by PEE, the female fetus and adult offspring that fed normal diet (ND) or HFD were sacrificed. The results showed that, in PEE + ND group, serum corticosterone (CORT) slightly decreased and insulin-like growth factor-1 (IGF-1) and glucose increased with partial catch-up growth; In PEE + HFD group, serum CORT decreased, while serum IGF-1, glucose and triglyceride (TG) increased, with notable catch-up growth, higher metabolic status and NAFLD formation. Enhanced liver expression of the IGF-1 pathway, gluconeogenesis, and lipid synthesis as well as reduced expression of lipid output were accompanied in PEE + HFD group. In PEE fetus, serum CORT increased while IGF-1 decreased, with low body weight, hyperglycemia, and hepatocyte ultrastructural changes. Hepatic IGF-1 expression as well as lipid output was down-regulated, while lipid synthesis significantly increased. Based on these findings, we propose a “two-programming” hypothesis for an increased susceptibility to HFD-induced NAFLD in female offspring of PEE. That is, the intrauterine programming of liver glucose and lipid metabolic function is “the first programming”, and postnatal adaptive catch-up growth triggered by intrauterine programming of GC-IGF1 axis acts as “the second programming”. - Highlights: • Prenatal ethanol exposure increase the susceptibility of NAFLD in female offspring. • Prenatal ethanol exposure reprograms fetal liver’s glucose and lipid metabolism . • Prenatal ethanol exposure cause the adaptive change of glucocorticoid-IGF1 axis.
60 APPLIED LIFE SCIENCES↗
Hydrogeologic Setting and Groundwater Contaminant Conceptual Model, Los Alamos National Laboratory - 18681
Our understanding of the complex hydrogeologic setting at Los Alamos National Laboratory (LANL) has evolved significantly over the previous decade. The semi-arid, high-desert setting consists of generally dry drainages in canyons that head either in uplands to the west of the Laboratory or on the high mountain-front plateau where the Laboratory is spread across approximately 40 square miles. Some canyon drainages have spatially limited reaches with perennial surface water from natural runoff and spring sources and/or from permitted effluent sources. The Rio Grande rift basin-fill stratigraphy includes primary volcanic deposits from pyroclastic eruptions and intermediate composition lava flows, and fluvial and alluvial fan deposits. Highly complex and spatially variable stratigraphy governs the occurrences of three groundwater zones: shallow 'alluvial groundwater', deep perched groundwater, and a thick 'regional' aquifer that is the water supply for the community of Los Alamos and the Laboratory. The current understanding of the hydrogeologic framework was greatly expanded as part of a site hydrogeologic characterization program completed in 2005. Higher resolution information exists in area where more detailed groundwater characterization has been conducted to support specific project objectives. A conceptual model for occurrences of contaminants in each of the three groundwater zones is governed by four factors: contaminant solubility/mobility, the mass of historical release, presence of a continuous hydraulic driver, and 'breakthrough' geology, defined as geology conducive to infiltration of shallow groundwater to deeper groundwater zones. The Laboratory's operations were historically somewhat spatially partitioned. Most of the radionuclide work (and historical releases) was conducted in the northern portion of the Laboratory, high explosives work has taken place exclusively in the southwestern portion, and treated sanitary effluent was released at a limited number of outfalls. Historical material disposal areas (MDAs) are dispersed throughout the Laboratory, and active MDAs are all located on a single dry mesa at the eastern part of the Laboratory. Evidence exists of transport of anthropogenic constituents to the regional aquifer. However, years of groundwater characterization have identified only two cases for which all the key factors were present and a complete contaminant pathway to the regional aquifer has resulted in contamination at levels above an applicable standard. Hexavalent chromium contamination associated with historical use as a corrosion inhibitor in a power plant is present beneath Mortandad Canyon, and RDX contamination associated with high-explosives machining is present beneath Canon de Valle. Each of those project areas have refined conceptual and numerical models that address contaminant migration pathways, spatial extent of perched-intermediate groundwater, mass balance, and fate and transport within the regional aquifer. No known contamination is present in the regional aquifer associated with MDAs, and interestingly, much of the Laboratory's groundwater background dataset is from wells located beneath active MDAs. A comprehensive groundwater monitoring program is in place to track the evolution of chromium and RDX contamination, and to identify any other constituents that may be attributable to historical LANL operations. (authors)
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
Mobilizing mine lands for biobased decarbonization strategies
Over 163 000 ha of mine lands in Pennsylvania (PA) have the potential to produce willow as a feedstock for renewable energy generation. Each year these lands could produce between 454 000 and 907 000 dry Mg of willow, which can be a feedstock for bioenergy (i.e., biopower) with carbon capture and sequestration (BECCS) or sustainable aviation fuel (SAF) production. We used a spatially explicit model to explore cost-minimized allocation of willow biomass from abandoned mine lands (AML) to be used for BECCS or SAF production and to abate carbon dioxide. The results suggest that between 454 000 and 907 000 dry Mg of biomass can be produced on AML in PA at costs from $94 to $250 per dry Mg. This AML willow biomass could be combined with other available biomass and aggregated to ten facilities to produce 17.9 TWh of power; alternatively, it could produce 958 million liters of jet fuel, 638 million liters of renewable diesel, and 1.289 billion liters of naphtha, along with 0.735 TWh of electricity. From this analysis, in PA, under the BECCS pathway, up to 36 million Mg per year of CO2 could be abated at costs of up to $134 per Mg; under the SAF pathway, up to 17.5 million Mg per year of CO2 could be abated at costs up to $150 per Mg of CO2. The use of mine land willow as a supplemental feedstock for SAF and BECCS would need strong incentive programs if costs of production are to be comparable with production on agricultural land.
Wahlstrom, Mallory [Pennsylvania State University]↗
Update on the Thermal Hydraulic Investigations of a Horizontal Dry Cask Simulator
The thermal performance of commercial spent nuclear fuel dry storage casks is evaluated through detailed numerical analysis. These modeling efforts are completed by the vendor to demonstrate performance and regulatory compliance. The calculations are then independently verified by the Nuclear Regulatory Commission (NRC). Canistered dry storage cask systems rely on ventilation between the inner canister and the overpack to convect heat away from the canister to the surrounding environment for both horizontal and vertical configurations. Recent advances in dry storage cask designs have significantly increased the maximum thermal load allowed in a canister in part by increasing the efficiency of internal conduction pathways and by increasing the internal convection through greater canister helium pressure. Carefully measured data sets generated from testing of full-sized casks or smaller cask analogs are widely recognized as vital for validating these models. While several testing programs have been previously conducted, these earlier validation studies did not integrate all the physics or components important in a modern, horizontal dry cask system. The purpose of the present investigation is to produce data sets that can be used to benchmark the codes and best practices presently used to determine cladding temperatures and induced cooling air flows in modern horizontal dry storage systems. The horizontal dry cask simulator (HDCS) has been designed to generate this benchmark data and add to the existing knowledge base. The objective of the HDCS investigation is to capture the dominant physics of a commercial dry storage system in a well-characterized test apparatus for any given set of operational parameters. The close coupling between the thermal response of the canister system and the resulting induced cooling air flow rate is of particular importance.
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
Boundary Conditions for the Paleoenvironment: Chemical and Physical Processes in Dense Interstellar Clouds: Summary of Research
The basic theme of this program was the study of molecular complexity and evolution for the biogenic elements and compounds in interstellar clouds and in primitive solar system objects. Research included the detection and study of new interstellar and cometary molecules and investigation of reaction pathways for astrochemistry from a comparison of theory and observed molecular abundances. The latter includes studies of cold, dark clouds in which ion-molecule chemistry should predominate, searches for the effects of interchange of material between the gas and solid phases in interstellar clouds, unbiased spectral surveys of particular sources, and systematic investigation of the interlinked chemistry and physics of dense interstellar clouds. In addition, the study of comets has allowed a comparison between the chemistry of such minimally thermally processed objects and that of interstellar clouds, shedding light on the evolution of the biogenic elements during the process of solar system formation. One PhD dissertation on this research was completed by a graduate student at the University of Massachusetts. An additional 4 graduate students at the University of Massachusetts and 5 graduate students from other institutions participated in research supported by this grant, with 6 of these thus far receiving PhD degrees from the University of Massachusetts or their home institutions. Four postdoctoral research associates at the University of Massachusetts also participated in research supported by this grant, receiving valuable training.
Irvine, William M.↗
Microalgae Feedstocks for Aviation Fuels
There is significant global interest in developing, testing, and using alternative jet fuels for both commercial and military use in an effort to create a sustainable and stable fuel supply while reducing greenhouse gas emissions. Currently, the aviation industry is entirely dependent on a finite-supply of petroleum based fuel sourced in part by politically and economically unstable regions of the world. Commercial jet fuel use within the contiguous United States (CONUS) was 17.8 billion gallons per year (BGY) in 2009, while jet fuel use in 2010 by the U.S. Air Force (USAF), Navy, and Army was 1.5 BGY, 0.6 BGY, and 0.8 BGY, respectively (Carter et al., 2011). U.S. commercial and military aviation sectors have set ambitious near-term alternative fuel and environmental performance targets. This includes a tentative Federal Aviation Administration (FAA) goal of 1 BGY alternative fuel use by commercial aircraft by 2018. The USAF has set a target of 50% for USAF domestic aviation via alternative fuels by 2016 (0.73 BGY), and 50% of the Navy’s total energy consumption afloat (0.3 BGY) will come from alternative fuels by 2020 (Carter et al., 2011). If these targets become policy, at least 2 BGY of domestically-produced alternative jet fuel will be required by 2020. The Energy Independence and Security Act (EISA) of 2007 established production requirements for domestic alternative fuels under the Renewable Fuel Standard (RFS). For example, 36 billion gallons of renewable fuel must be produced by 2022, of which 21 billion gallons shall be advanced biofuels. EISA defines advanced biofuels as non-corn starch derived biofuels having lifecycle greenhouse gas emissions 50% lower than gasoline. There a number of potential fuel pathways for meeting the RFS. One of these is biomass-based diesel, including jet fuel (Schnepf and Yacobucci, 2013). The U.S. Department of Energy (DOE) Bioenergy Technologies Office (BETO) has a stated goal in its 2013 Multi-Year Program Plan (USDOE, 2013) to support the RFS through development of “…commercially viable biomass utilization technologies to encourage the creation of a new domestic bioenergy industry…”. BETO has also recognized the potential for aviation biofuels to support the bioenergy industry, seeing drop-in bio-based jet fuels one of the viable alternatives for the aviation industry and the military to meet their ambitious near-term GHG reduction targets (USDOE, 2014). One of the important Multi-year Program Plan Targets (USDOE, 2013) is to establish feedstock resource assessment models to evaluate the geographic, economic, quality and environmental criteria for which 20 million metric tons of ash free dry weight (AFDW) algal biomass can be produced by 2022. Toward meeting the EISA requirements, algal biofuels may offer a number of advantages. They can produce a range of biofuel feedstocks suitable for diesel and aviation fuels. Microalgae, on a strain-specific basis, can be cultivated using impaired water including saline, and/or brackish pumped groundwater or seawater, treated industrial wastewater, municipal sewage effluent, and produced water generated from oil and gas drilling operations. Additionally, microalgae require nitrogen and phosphates as essential nutrients and could provide water treatment co-benefits to municipalities, industry, and the environment.
algae↗
Development of Novel Non-Pt Group Metal Electrocatalysts for PEM Fuel Cell Applications
The objective of this multi-institutional effort was to comprehensively pursue the goal of eliminating noble metal (Pt group metals, PGM) from the cathodic oxygen reduction reaction (ORR) electrode thereby providing a quantum leap in lowering the overall PGM loading in a polymer electrolyte fuel cell (PEMFC). The overall project scope encompassed (a) comprehensive materials discovery effort, (b) a concomitant effort to scale up these materials with very high ( ±5%) reproducibility, both intra and inter, (c) understanding mass transport in porous medium both in gas diffusion and micro-porous layers for enhanced areal activity, (d) understanding mechanistic aspects of active site structure and ORR electrocatalytic pathway. Overall project milestones and metrics were (a) first phase effort based on performance in oxygen where the project’s Go/No-Go decision point milestone of 100 mA/cm 2 at 0.8 V (internal resistance-free, iR-free) at 80°C, pure H 2 /O 2 , with 1.5 bar total pressure was met. Subsequently, the principle objectives were to (a) transition the project from H 2 /O 2 to H 2 /Air with slated target of exceeding 30 mA/cm 2 @ 0.8 V, 2.5 bar total pressure and an end of the project target of 1 A/cm 2 @ 0.4 V (same total pressure), both under 100% relative humidity. The target for catalyst material scale up was to achieve 100 g batch size at the end of the program. This scale up target had a quality control milestone of less than 5% variation of activity measured with H 2 /Air (2.5 bar total pressure) at 0.8 V. In addition, the project also aimed at arriving at a unified understanding of the nature of active sites in these catalysts as well as some preliminary understanding of the mechanistic pathway. Also addressed is the development of an integrated method for determination of mass transport parameters using a combination of Helox experiments and modeling of the gas diffusion media, especially the micro-porous layer on the gas diffusion electrode (GDE). Detailed aspects of technical metrics and milestones are provided in Table 1 of the final report. Besides the success in meeting the DOE milestones in areal activities for oxygen and air described above one of the key successes of this effort was in understanding the nature of the active site(s) and aspects of the ORR pathway. In this it should be noted that the materials discovery effort provided for use of unconventional approaches, some of which led to very active catalysts. This aspect is described in detail in the final report. From a mechanistic perspective, a combination spectroscopic techniques confirmed that the high activity observed for most pyrolyzed Fe-based catalysts, irrespective of the precursors materials (macrocycles or individual Fe, N, and C precursors), the synthesis method (wet chemical impregnation or SSM), and final Fe-species (with or without inorganic iron species), can mainly be attributed to a single active site: non-planar Fe-N 4 moiety embedded in distorted carbon matrix characterized by a high potential for the Fe 2+/3+ redox transition in acidic electrolyte/environment, which is likely formed via the covalent incorporation of distorted Fe-N4 moieties in the defective centers on the carbon basal plane or in armchair edges of two adjacent graphene layers. This Fe 2+ -N 4 active site at 0.3 V undergoes redox transition to a pentacoordinate HO₋Fe 3+ ₋N 4 at 0.90 V, and the adsorption of the *OH trigged by the Fe 2+ /Fe 3+ redox transition poisons the active sites, thereby providing experimental evidence of the redox mechanism. Moreover, a highly active MOF-based catalyst devoid of any Fe-N moieties was also developed, and the active sites were identified as nitrogen-doped carbon fibers with embedded iron particles that are not directly involved in the oxygen reduction pathway. The high ORR activity and durability of catalysts involving this site in fuel cells are attributed to the high density of active sites and the elimination or reduction of Fenton-type processes. The latter are initiated by hydrogen peroxide but are known to be accelerated by iron ions exposed to the surface, resulting in the formation of damaging free-radicals. We expect that the comprehensive understanding of the synthesis-products correlations, nature of active sites, and the reaction mechanisms acquired here by systematically studying a broad variety of M-N-C materials under in situ conditions will provide guidelines to rational design of this type of non-PGM catalysts.
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