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All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Detection of Lung Contour with Closed Principal Curve and Machine Learning

Radiation therapy plays an essential role in the treatment of cancer. In radiation therapy, the ideal radiation doses are delivered to the observed tumor while not affecting neighboring normal tissues. In three-dimensional computed tomography (3D-CT) scans, the contours of tumors and organs-at-risk (OARs) are often manually delineated by radiologists. The task is complicated and time-consuming, and the manually delineated results will be variable from different radiologists. We propose a semi-supervised contour detection algorithm, which firstly uses a few points of region of interest (ROI) as an approximate initialization. Then the data sequences are achieved by the closed polygonal line (CPL) algorithm, where the data sequences consist of the ordered projection indexes and the corresponding initial points. Finally, the smooth lung contour can be obtained, when the data sequences are trained by the backpropagation neural network model (BNNM). We use the private clinical dataset and the public Lung Image Database Consortium and Image Database Resource Initiative (LIDC-IDRI) dataset to measure the accuracy of the presented method, respectively. To the private dataset, experimental results on the initial points which are as low as 15% of the manually delineated points show that the Dice coefficient reaches up to 0.95 and the global error is as low as 1.47 × 10{sup −2}. The performance of the proposed algorithm is also better than the cubic spline interpolation (CSI) algorithm. While on the public LIDC-IDRI dataset, our method achieves superior segmentation performance with average Dice of 0.83.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Increased acid resistance of the archaeon, Metallosphaera sedula by adaptive laboratory evolution

Abstract Extremely thermoacidophilic members of the Archaea such as the lithoautotroph, Metallosphaera sedula, are among the most acid resistant forms of life and are of great relevance in bioleaching. Here, adaptive laboratory evolution was used to enhance the acid resistance of this organism while genomics and transcriptomics were used in an effort to understand the molecular basis for this trait. Unlike the parental strain, the evolved derivative, M. sedula SARC-M1, grew well at pH of 0.90. Enargite (Cu3AsS4) bioleaching conducted at pH 1.20 demonstrated SARC-M1 leached 23.78 % more copper relative to the parental strain. Genome re-sequencing identified two mutations in SARC-M1 including a nonsynonymous mutation in Msed_0408 (an amino acid permease) and a deletion in pseudogene Msed_1517. Transcriptomic studies by RNA-seq of wild type and evolved strains at various low pH values demonstrated there was enhanced expression of genes in M. sedula SARC-M1 encoding membrane complexes and enzymes that extrude protons or that catalyze proton-consuming reactions. In addition, M. sedula SARC-M1 exhibited reduced expression of genes encoding enzymes that catalyze proton-generating reactions. These unique genomic and transcriptomic features support a model for increased acid resistance arising from enhanced control over cytoplasmic pH.

Ai, Chenbing↗
DOE OSTI2018

Reactivity Runaway Reduction When Using Enriched Uranium in a Lead Fast Reactor

The possibilities for reactivity runaway reduction in a fast reactor when using enriched uranium are examined. Specifically, an approach supposing partial compensation of reactivity runaway by the addition of Np or Am, as consumable absorbers, into the starting load is analyzed. It is shown that from the standpoint of the development of large-scale nuclear power generation based on BREST-type reactors the use of a uranium starting load becomes inexpedient in implementing this approach. A starting load consisting of a mixture of enriched uranium and plutonium from spent RBMK fuel is studied. The results indicate that it is possible to develop a core with reactivity runaway not exceeding the effective delayed-neutron fraction during the entire period of operation. The neutronics characteristics were calculated using the Arktika multigroup diffusion code. The RISK code was used to determine the change in the nuclide composition.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2018

Growth of Dehalococcoides mccartyi species in an autotrophic consortium producing limited acetate

The dechlorinating Dehalococcoides mccartyi species requires acetate as carbon source, but little is known on its growth under acetate limiting conditions. In this study, we observed growth and dechlorination of a D. mccartyi-containing mixed consortium in a fixed-carbon-free medium with trichloroethene in the aqueous phase and H 2 /CO 2 in the headspace. Around 4 mM formate was produced by day 40, while acetate was constantly below 0.05 mM. Microbial community analysis of the consortium revealed dominance by D. mccartyi and Desulfovibrio sp. (57 and 22% 16S rRNA gene copies, respectively). From this consortium, Desulfovibrio sp. strain F1 was isolated and found to produce formate and acetate (1.2 mM and 48 µM, respectively, by day 24) when cultivated alone in the above mentioned medium without trichloroethene. An established co-culture of strain F1 and D. mccartyi strain 195 demonstrated that strain 195 could grow and dechlorinate using acetate produced by strain F1; and that acetate was constantly below 25 µM in the co-culture. To verify that such low level of acetate is utilizable by D. mccartyi, we cultivated strain 195 alone under acetate-limiting conditions and found that strain 195 consumed acetate to below detection (5 µM). Based on the acetate consumption and cell yield of D. mccartyi, we estimated that on average 1.2 × 108 acetate molecules are needed to supply carbon for one D. mccartyi cell. Our study suggests that Desulfovibrio may supply a steady but low amount of fixed carbon to dechlorinating bacteria, exhibiting important implications for natural bio-attenuation when fixed carbon is limited.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2019

Characterizing organic carbon dynamics during biostimulation of a uranium contaminated field site

Uranium contamination of groundwater remains a pressing problem at many former uranium mining and milling operations, such as the Rifle, Integrated Field Research Challenge (IFRC) site. Biostimulation of the subsurface with an organic carbon source such as acetate, followed by the microbially-induced reductive precipitation of uranium has been proposed as an effective remediation strategy. While uranium bioreduction has been studied in several field experiments, the transformation and fate of injected carbon remains poorly understood. This study evaluated the impact of added organic carbon on the long-term biogeochemical attenuation of uranium in the subsurface of a former mill tailings site. Fluorescence and ultraviolet–visible absorbance analyses were used together with dissolved organic carbon (DOC) measurements to track organic carbon dynamics during and post-biostimulation of the 2011 Rifle IFRC experiment. An electron mass balance was performed on well CD01 to account for any unidentified carbon sinks. Measured DOC values increased to 1.76 mM-C during biostimulation, and to 3.18 mM-C post-biostimulation over background DOC values of 0.3–0.4 mM-C. Elevated DOC levels persisted for 90 days after acetate injections ceased. The electron mass balance revealed that assumed electron acceptors would not account for the total amount of acetate consumed. Excitation–emission matrices showed an increase in signals associated with soluble microbial products, during biostimulation, which disappeared post-biostimulation despite an increase in total DOC. Specific ultraviolet absorbance analyses, indicated that DOC present post-biostimulation is less aromatic in nature, compared to background DOC. Furthermore, our results suggest that microbes convert injected acetate into a form of solid phase organic matter that may be available to sustain iron reduction post-stimulation.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2018

Fire and Explosion Safe Technology of Storage and Regasification of Liquefied Petroleum Gas

The technology of storage and regasification of liquefied petroleum gas that implies storage in an isothermal tank and overheating the gas with subsequent supply of the vapor phase to the consumer is offered. The necessary storage and regasification temperatures are achieved by means of utilizing a vapor-compression refrigeration unit in the technological process. The technology allows to improve energy efficiency of the processes, reduce fire-and-explosion hazard, minimize LPG losses, exclude conditions formation of a combustible environment, regulate the storage temperature of LPG of various composition and efficiency of the regasification process, and ensure the composition of volatilized LPG remains constant during regasification.

02 PETROLEUM↗
DOE OSTI2016

The effect of African growth on future global energy, emissions, and regional development

In 2005 less than 15% of the world’s population lived in Africa, by the end of the 21st century more than one-fifth of the world’s population could live there. By dint of sheer numbers, Africa is a place to be reckoned with. But from a global perspective, Africa is not a major emitter of greenhouse gases or consumer of fossil energy today. However, Africa’s share of global emissions at the end of the century depends critically on assumptions about its growth in economic activity. This paper explores the implications of alternative assumptions about future rates of economic growth in Africa. It finds that assumptions about the rate of economic growth have profound implications for global economic activity, energy use, and greenhouse gas emissions. African emissions vary from 5% to 20% of global emissions, and emissions in Sub-Saharan Africa range from 2% to 10% of world emissions, depending on the model and scenario. In addition, affluence levels till the middle of the century remain low, as a result the population remains dependent on traditional bioenergy for the bulk of its residential energy needs. Although the share of electricity in final energy, electric capacity and electricity use per capita all rise with income, they do not reach levels commensurate with those in developed countries today. Hence, dedicated policies may be needed in order to address energy poverty and access issues in the region.

Calvin, Katherine V.↗
DOE OSTI2014

Bioenergy in Energy Transformation and Climate Management

Unlike fossil fuels, biomass is a renewable resource that can sequester carbon during growth, be converted to energy, and then re-grown. Biomass is also a flexible fuel that can service many end-uses. This paper explores the importance of bioenergy to potential future energy transformation and climate change management. Using a model comparison of fifteen models, we characterize and analyze future dependence on, and the value of, bioenergy in achieving potential long-run climate objectives—reducing radiative forcing to 3.7 and 2.8 W/m2 in 2100 (approximately 550 and 450 ppm carbon dioxide equivalent atmospheric concentrations). Model scenarios project, by 2050, bioenergy growth of 2 to 10% per annum reaching 5 to 35 percent of global primary energy, and by 2100, bioenergy becoming 15 to 50 percent of global primary energy. Non-OECD regions are projected to be the dominant suppliers of biomass, as well as consumers, with up to 35 percent of regional electricity from biopower by 2050, and up to 70 percent of regional liquid fuels from biofuels by 2050. Bioenergy is found to be valuable to many models with significant implications for mitigation costs and world consumption. The availability of bioenergy, in particular biomass with carbon dioxide capture and storage (BECCS), notably affects the cost-effective global emissions trajectory for climate management by accommodating prolonged near-term use of fossil fuels. We also find that models cost-effectively trade-off land carbon and nitrous oxide emissions for the long-run climate change management benefits of bioenergy. Overall, further evaluation of the viability of global large-scale bioenergy is merited.

Rose, Steven K.↗
DOE OSTI2015

Building a sustained climate assessment process

The leaders and authors of the Third US National Climate Assessment (NCA3) developed new modes of engaging academia, the private sector, government agencies and civil society to support their needs for usable, rigorous, and timely information and better connect science and decision-making. A strategic vision for assessment activities into the future was built during the NCA3 process, including recommendations on how to establish a sustained assessment process that would integrate evolving scientific understanding into decision making to manage the risks of climate change over time. This vision includes a collaborative assessment process that involves partnerships across a diverse and widely distributed set of non-governmental and governmental entities. The new approach to assessments would produce timely, scientifically sound climate information products and processes, rather than focusing on the production of single quadrennial synthesis reports. If properly implemented, a sustained assessment would be more efficient and cost-effective, avoiding the painful and time-consuming process of beginning the assessment process anew every 4 years. This ongoing assessment would also encourage scientific and social innovations and explore new insights and opportunities, building the capacity to advance the development and delivery of climate information to meet societal requirements and benefit from scientific opportunities.

Buizer, James L.↗
DOE OSTI2016

Brown tree snake ( Boiga irregularis ) population density and carcass locations following exposure to acetaminophen

Mass aerial delivery of dead mouse baits treated with acetaminophen has been evaluated as a means to reduce brown treesnake (Boiga irregularis) populations over large areas, increasing the likelihood of wide-scale eradication on Guam. Given the high density of snakes in some areas of their invasive range, eradication efforts could result in a resource pulse that may influence food web dynamics and the indirect transport of acetaminophen among trophic levels. In this study, we evaluated abundance, habitat type, and snake size (i.e., age) within two study sites on Guam, a secondary limestone forest (upland) and an abandoned coconut plantation (coastal), to determine how experimentally dosing snakes with acetaminophen is likely to influence carrion availability. We found snakes trapped in 3.24 ha plots occurred in greater abundance (population size = 72.5 snakes; SE = 8.8) and were significantly larger (978.6 mm, SE = 14.9) in the coastal than in the upland site (population size = 26.9, SE = 21.5; length = 903.0 mm, SE = 15.9). Despite these differences, carcasses of snakes that died after consuming acetaminophen-laced mice (80 mg) were recovered in consistent locations between sites, with 92% located on the ground, 4% in trees, and 4% found in rock cavities at both sites. Given that most snakes died on the ground rather than in the tree canopy, our results suggest that many poisoned snake carcasses will be accessible to a wide range of potential scavengers, possibly influencing food web dynamics and potentially contributing to indirect toxicant transfer within affected ecosystems.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Evaluating the regional risks to food availability and access from land-based climate policies in an Integrated Assessment Model

Mitigating greenhouse gas (GHG) emissions is necessary to reduce the overall negative climate change impacts on crop yields and agricultural production. However, certain mitigation measures may generate unintended consequences to food availability and food access due to both land use competition and economic burden of mitigation. Integrated assessment models (IAM) are generally used to evaluate these policies; however, currently these models may not capture the importance of income and food prices for hunger and overall economic wellbeing. Here, we implement a measure of food security that captures the nutritional and economic aspects as the total expenditures on staple foods divided by income and weighted by total caloric consumption in an IAM, the Global Change Analysis Model (GCAM4.0). We then project consumer prices and our measure of food security along the Shared Socioeconomic Pathways (SSPs). Sustained economic growth underpins increases in caloric consumption and lowering expenditures on staple foods. Strict conservation policies affect food accessibility in a larger number of developing countries, whereas the negative effects of pricing terrestrial emissions is more concentrated on the poor in Sub-Saharan Africa, by substantially replacing their cropland with forests and affecting the production of key staples.

Cui, Ryna↗
DOE OSTI2016

Emergency Cooling of Nuclear Power Plant Reactors With Heat Removal By a Forced-Draft Cooling Tower

The feasibility of heat removal during emergency cooling of a reactor by a forced-draft cooling tower with accumulation of the peak heat release in a volume of precooled water is evaluated. The advantages of a cooling tower over a spray cooling pond are demonstrated: it requires less space, consumes less material, employs shorter lines in the heat removal system, and provides considerably better protection of the environment from wetting by entrained moisture.

42 ENGINEERING↗
DOE OSTI2014

Analysis and modeling of Nannochloropsis growth in lab, greenhouse, and raceway experiments

Efficient production of algal biofuels could reduce dependence on foreign oil by providing a domestic renewable energy source. Moreover, algae-based biofuels are attractive for their large oil yield potential despite decreased land use and natural resource (e.g., water and nutrients) requirements compared to terrestrial energy crops. Important factors controlling algal lipid productivity include temperature, nutrient availability, salinity, pH, and the light-to-biomass conversion rate. Here, computational approaches allow for inexpensive predictions of algae growth kinetics for various bioreactor sizes and geometries without the need for multiple, expensive measurement systems. Parametric studies of algal species include serial experiments that use off-line monitoring of growth and lipid levels. Such approaches are time consuming and usually incomplete, and studies on the effect of the interaction between various parameters on algal growth are currently lacking. However, these are the necessary precursors for computational models, which currently lack the data necessary to accurately simulate and predict algae growth. In this work, we conduct a lab-scale parametric study of the marine alga Nannochloropsis salina and apply the findings to our physics-based computational algae growth model. We then compare results from the model with experiments conducted in a greenhouse tank and an outdoor, open-channel raceway pond. Results show that the computational model effectively predicts algae growth in systems across varying scale and identifies the causes for reductions in algal productivities. Applying the model facilitates optimization of pond designs and improvements in strain selection.

09 BIOMASS FUELS↗
DOE OSTI2025

Combining Deep Learning and scatterControl for High-Throughput X-ray CT Based Non-Destructive Characterization of Large-Scale Casted Metallic Components

X-ray computed tomography (XCT) is essential for nondestructive evaluation and quality control of large-scale metal components. XCT imaging, however, faces significant challenges from metal artifacts, particularly those caused by Compton scattering, which degrade image quality and obscure critical details. Hardware-based solutions (e.g. scatterControl) offer advancements by intercepting scattered photons and reducing artifacts, but they can be time-consuming and require additional processing. Here, we propose modifying and leveraging a novel deep learning (DL) framework, Simurgh, to enhance and accelerate scatter correction in XCT. By combining scatterControl with DL-based artifact removal, we demonstrate significant reduction in scan time while producing high-quality reconstructions. Through extensive evaluation on industrial XCT data, we show that our methods reduce scan time by up to more than 10 x while preserving flaw detectability. Quantitative analysis across multiple segmentation techniques confirms that Simurgh-based reconstructions consistently outperform traditional Feldkamp-Davis-Kress, model-based iterative reconstruction, and commercial DL models in both pixel-level and task-specific evaluations, enabling scalable, high-throughput XCT workflows for characterization of large scale components in applications such as casting and metal additive manufacturing.

Complex metal parts↗
DOE OSTI2018

Effects of Aging and Different Mechanical Recycling Processes on the Structure and Properties of Poly(lactic acid)-clay Nanocomposites

The growing use of poly(lactic acid) (PLA) and PLA-based nanocomposites in packaging has raised the interest of studying the mechanical recycling of the wastes and the properties of the recycled materials. The main objective of this work was to study the effect of two different mechanical recycling processes on the structure and properties of a PLA-montmorillonite nanocomposite. The two recycling processes included accelerated thermal and photochemical aging steps to simulate the degradation experienced by post-consumer plastics during their service life. One of them also included a demanding washing process prior to the reprocessing. A decrease in the molecular weight of PLA was observed in the recycled materials, especially in those subjected to the washing step, which explained the small decrease in microhardness and the increased water uptake at long immersion times. Water absorption at short immersion times was similar in virgin and recycled materials and was accurately described using a Fickian model. The recycled materials showed increased thermal, optical and gas barrier properties due to the improved clay dispersion that was observed by XRD and TEM analysis. The results suggest that recycled PLA-clay nanocomposites can be used in demanding applications.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2019

Synthesis of Recycled Poly(ethylene terephthalate)/Polyacrylonitrile/Styrene Composite Nanofibers by Electrospinning and Their Mechanical Properties Evaluation

Consumption of polyethylene terephthalate (PET) products has increased dramatically in recent decades, resulting in the generation of a large amount of PET waste. For that reason, is necessary to find a new application of recycled material. In this article, we report the synthesis and characterization of recycled poly (ethylene terephthalate) (RPET) obtained from the chemical recycling of post-consumer PET bottles by glycolysis method and the formation of composites nanofibers RPET/polyacrylonitrile (PAN)/styrene (ST). The RPET synthesis was studied through infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). The viscosity and frequency sweep of the polymeric solutions was evaluated. The composites nanofibers were elaborated by the electrospinning technique and characterized by scanning electron microscopy (SEM), FT-IR, TGA/DSC and nanoindentation. The RPET/PAN/ST composite nanofibers present an average diameter of 456 nm and higher thermal stability compared PAN fibers. The mechanical properties such as hardness and elastic modulus were 4.5 and 7.5 times PAN fibers values, respectively.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2019

Bioactivity Potentials of Biodegradable Chitosan/Gelatin Film Forming Solutions Combined with Monoterpenoid Compounds

Novel food packaging systems including biodegradable/edible films have been introduced to the market for consumers who desire natural products for their nutrition. Biochemically active plant compounds are added to the biopolymer-based films to improve their functionality. Within the present study, chitosan (1%) and gelatin (4%) biopolymer-based film forming solutions (FFSs) combined with 1, 2, 5 and 10% (v/v) eugenol, pulegone and carvacrol, monoterpenoid compounds, were evaluated for their antimicrobial and antioxidative potential. Antioxidant activities and total phenolic contents (TPC) of the FFSs were determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity and Folin–Ciocalteau assays, respectively. Screening the antimicrobial activity of FFSs were performed against food spoilage microorganisms including Bacillus cereus, Escherichia coli, Salmonella typhimurium, Staphylococcus aureus and Listeria monocytogenes and a fungi, Candida albicans by using agar well diffusion method. The chitosan FFS containing 10% carvacrol had greater TPC (3857.3 ± 0.07 mg gallic acid equivalent/L). The highest antioxidative capacity was observed for the chitosan FFS containing 10% eugenol as 97.92 ± 0.01%. FFSs with monoterpenoids showed promising antimicrobial activities against tested microorganisms. Based on antioxidative and antimicrobial potentials of the FFSs, it can be envisaged to use monoterpenoid incorporation to biopolymer films for food packaging applications.

60 APPLIED LIFE SCIENCES↗