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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,657 records · Page 92
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Angiographic Anatomy and Relevance of 3 and 9 O’clock Arteries During Radioembolization

Purpose3 and 9 o’clock arteries (3&9As) which supply the common hepatic duct connect hepatic with duodenal/pancreatic territories. The study purpose is to describe the angiographic anatomy of 3&9As and discuss their relevance when performing radioembolization (RE) of liver malignancies.Materials and MethodsThe anatomy of the 3&9As was systematically investigated by a retrospective analysis of angiograms, technetium Tc-99 m-macroaggregated albumin (MAA) scintigrams, yttrium-90 (Y90) Bremsstrahlung-SPECT/CT datasets, and clinical data of 153 patients who underwent RE between 2010 and 2013.ResultsAnalysis of preprocedural angiograms identified 3&9As in 36 (24%) of the 153 patients. Following embolization of the gastroduodenal artery, 3&9As were seen in 53 cases (35%). The three most common origins of the 3&9As were the right hepatic artery (n = 14), the cystic artery (n = 11), and S5 and S6 segmental arteries (n = 5 each). Extrahepatic Tc-99 m-MAA deposition in the territory of the 3&9As was significantly more frequent when 3&9As were detectable on preprocedural angiograms (28%{sub visible} vs. 11%{sub not} {sub visible}; p = 0.001) and especially when the 3&9As were not embolized or bridged prior to RE (50%{sub not} {sub occluded/bridged} vs. 19%{sub occupied/bridged}; p = 0.043). The presence of extrahepatic Y90 Bremsstrahlung after RE (n = 17) was attributable to microsphere diversion via the 3&9A territory in four patients and possible diversion via this territory in nine patients. Five of these 13 patients presented with epigastric pain, nausea, or vomiting (CTCAE severity grade ≤ 3) (p = 0.014).Conclusion3&9As are commonly detectable during evaluation angiography prior to RE, have a variable angioanatomic origin, and should be prophylactically occluded to prevent complications.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Which G-Tube to Use in Pullers: Assessment of Pull Pressures on Skin Models to Determine Optimal Catheter Choice in Patients with Recurrent Pulled Gastrostomy Tubes

Introduction: Pulled or dislodged gastrostomy catheters represent a common complication associated with percutaneous gastrostomy and are a common cause of recurrent visits in patients with altered mental status. We intended to perform an experiment to compare the pull forces required to dislodge different commonly used gastrostomy catheters. Materials and Methods: We used a digital force gauge device to measure the pull forces required to dislodge three types of 20 French gastrostomy catheters in double-layer skin models. These included the Flow 20 Pull Method (Cook Medical, Bloomington, IN, USA), Entuit Gastrostomy BR Balloon Retention feeding tube (Cook Medical, Bloomington, IN, USA), and Ponsky Non-Balloon Replacement Gastrostomy Tube (CR Bard Inc, Salt Lake City, Utah, USA). The catheters were inserted into the skin model using the same technique as would be utilized in a patient. Results: The mean forces measured to dislodge the per-oral Flow 20 Pull Method, Entuit Thrive Balloon Retention, and button-type retention Ponsky replacement catheters were 35.6, 22.8, and 20.6 Newtons, respectively. The pull method per-oral gastrostomy catheter required significantly more pull force to dislodge than both the Ponsky button-type retention catheter and the Entuit balloon retention catheters. There was no significant difference in the pull force required to dislodge the Ponsky replacement catheter and the Entuit balloon retention catheter. Conclusions: Per-oral image-guided gastrostomy with pull-method button-type retention catheters may be the ideal choice in patients at high risk of tube dislodgment.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Current Trends in the Treatment of Hepatocellular Carcinoma with Transarterial Embolization: Variability in Technical Aspects

Purpose: While transarterial chemoembolization (TACE) is a mainstay of treatment for unresectable hepatocellular carcinomas (HCCs), technical aspects have varied considerably in the literature. These variations lead to heterogeneity and make meaningful comparisons between articles difficult. The goal of this survey was to report international embolization practices for the treatment of HCC in an effort to understand current treatment strategies as a first step toward technique standardization. Materials and Methods: An anonymous 18 question online survey, evaluating technical aspects of TACE, was distributed via e-mail to practicing members of the five largest interventional radiology societies in Chinese and English. A total of 1160 responses were obtained from 62 countries. Results: Between regions, there were significant statistical differences in nearly all responses, including the amount of ethiodol oil used for cTACE (p = < 0.001). Practitioners most commonly used greater than 7.5 ml of ethiodol oil (240/506, 47.4%) and most did not utilize a specific mixing method (249/505, 49.3%). Particles utilized varied by geographical region (p = < 0.001), spherical embolic particles were slightly favored (363/757, 47.9%), followed closely by gelatin-based or sponge particles (279/680, 36.8%). Gelfoam was used almost exclusively in Japan and Korea (79/82 responses). LC/DC beads were the most commonly used drug-eluting bead (DEB) (450/742, 60.6%), with the most common size of DEB being 100–300 μm (354/690, 51.3%, p = 0.07). Conclusion: Technical aspects of transarterial embolization for HCC vary significantly by geographical location.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Clinical Outcome of the Visible Coil During Endoscopy After Transcatheter Arterial Embolization for Gastrointestinal Bleeding

Purpose: This study was designed to evaluate the clinical outcome of the visible coil during endoscopy after transcatheter arterial embolization (TAE) for gastrointestinal bleeding. Methods: We retrospectively reviewed the medical records of 1415 patients who underwent TAE for gastrointestinal bleeding between 2001 and 2017. Among these 1415 patients, 70 underwent TAE using coils and consecutive follow-up endoscopy. Finally, 11 patients with an extravascular coil seen on follow-up endoscopic examination were included in this study. We evaluated the underlying cause of the gastrointestinal bleeding, the technical and clinical success rates, the type of extravascular coil after TAE, and the clinical outcomes of the extravascular coil seen on follow-up endoscopic examination. Results: Of the 11 patients, the most common underlying cause of gastrointestinal bleeding was a duodenal ulcer (n = 7). On angiography, the bleeding artery was most commonly found in the gastroduodenal artery (n = 6). The technical success and clinical success rates of TAE were 100% and 90.9%, respectively. The type of extravascular coil found on endoscopic examination was classified by submucosal migration (n = 6) and protrusion (n = 5). On second-look endoscopic evaluation, 10 of 11 (90.9%) patients showed healing ulceration. On the final-look endoscopic evaluation, healing ulceration without further bleeding was seen in one (9.1%) patient and scar formation was seen in ten (90.9%) patients. Conclusions: Extravascular coil after TAE for gastrointestinal bleeding is rare, and the most common underlying cause is duodenal ulcer bleeding. The extravascular coils eventually show a healing process with adequate treatment of underlying bowel pathologies.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2022

Association of small vessel disease with tau pathology

Emerging evidence suggests that small vessel disease (SVD) is a risk factor for clinical dementia and may contribute to AD neuropathological changes. Watershed brain regions are located at the most distal areas between arterial territories, making them vulnerable to SVD-related changes. We examined the association of pathologic markers of SVD, specifically arteriolosclerosis in watershed brain regions, with AD pathologic changes. Participants (N= 982; mean age-at-death = 90; 69% women) were enrolled as part of one of two cohort studies of aging and dementia. At autopsy, neuropathological evaluation included semi-quantitative grading of arteriolosclerosis pathology from 2 cortical watershed regions: the anterior watershed (AWS) and posterior watershed (PWS), densities for cortical β-amyloid and tau-tangle pathology, and other common age-related pathologies. Linear regression models examined the association of watershed arteriolosclerosis pathology with β-amyloid and tau-tangle burden. In follow-up analyses, available ex-vivo MRI and proteomics data in a subset of decedents were leveraged to examine the association of whole brain measure of WMH, as a presumed MRI marker of SVD, with β-amyloid and tau-tangle burden, as well as to examine the association of watershed arteriolosclerosis with proteomic tau. Watershed arteriolosclerosis was common, with 45% of older persons having moderate-to-severe arteriolosclerosis pathology in the AWS region, and 35% in the PWS. In fully adjusted models that controlled for demographics and common age-related pathologies, an increase in severity of PWS arteriolosclerosis was associated with a higher burden of tau-tangle burden, specifically neocortical tau burden, but not with β-amyloid. AWS arteriolosclerosis was not associated with β-amyloid or tau pathology. Ex-vivo WMH was associated with greater tau-tangle pathology burden but not β-amyloid. Furthermore, PWS arteriolosclerosis was associated with higher abundance of tau phosphopeptides, that promote formation of tau aggregates. These data provide compelling evidence that SVD, specifically posterior watershed arteriolosclerosis pathology, is linked with tau pathological changes in the aging brain.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2019

Rosette core fungal resistance in Arabidopsis thaliana

Main conclusion: Unlike rosette leaves, the mature Arabidopsis rosette core can display full resistance to Botrytis cinerea revealing the importance for spatial and developmental aspects of plant fungal resistance. Abstract: Arabidopsis thaliana is a model host to investigate plant defense against fungi. However, many of the reports investigating Arabidopsis fungal defense against the necrotrophic fungus, Botrytis cinerea, utilize rosette leaves as host tissue. Here we report organ-dependent differences in B. cinerea resistance of Arabidopsis. Although wild-type Arabidopsis rosette leaves mount a jasmonate-dependent defense that slows fungal growth, this defense is incapable of resisting fungal devastation. In contrast, as the fungus spreads through infected leaf petioles towards the plant center, or rosette core, there is a jasmonate- and age-dependent fungal penetration blockage into the rosette core. In this paper, we report evidence for induced and preformed resistance in the rosette core, as direct rosette core inoculation can also result in resistance, but at a lower penetrance relative to infections that approach the core from infected leaf petioles. The Arabidopsis rosette core displays a distinct transcriptome relative to other plant organs, and BLADE ON PETIOLE (BOP) transcripts are abundant in the rosette core. The BOP genes, with known roles in abscission zone formation, are required for full Arabidopsis rosette core B. cinerea resistance, suggesting a possible role for BOP-dependent modifications that may help to restrict fungal susceptibility of the rosette core. Finally, we demonstrate that cabbage and cauliflower, common Brassicaceae crops, also display leaf susceptibility and rosette core resistance to B. cinerea that can involve leaf abscission. Thus, spatial and developmental aspects of plant host resistance play critical roles in resistance to necrotrophic fungal pathogens and are important to our understanding of plant defense mechanisms.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

An empirical investigation of organic software product lines

Abstract Software product line engineering is a best practice for managing reuse in families of software systems that is increasingly being applied to novel and emerging domains. In this work we investigate the use of software product line engineering in one of these new domains, synthetic biology. In synthetic biology living organisms are programmed to perform new functions or improve existing functions. These programs are designed and constructed using small building blocks made out of DNA. We conjecture that there are families of products that consist of common and variable DNA parts, and we can leverage product line engineering to help synthetic biologists build, evolve, and reuse DNA parts. In this paper we perform an investigation of domain engineering that leverages an open-source repository of more than 45,000 reusable DNA parts. We show the feasibility of these new types of product line models by identifying features and related artifacts in up to 93.5% of products, and that there is indeed both commonality and variability. We then construct feature models for four commonly engineered functions leading to product lines ranging from 10 to 7.5 × 10 20 products. In a case study we demonstrate how we can use the feature models to help guide new experimentation in aspects of application engineering. Finally, in an empirical study we demonstrate the effectiveness and efficiency of automated reverse engineering on both complete and incomplete sets of products. In the process of these studies, we highlight key challenges and uncovered limitations of existing SPL techniques and tools which provide a roadmap for making SPL engineering applicable to new and emerging domains.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2020

A Comprehensive Scientific Survey of Excipients Used in Currently Marketed, Therapeutic Biological Drug Products

The steady development of biotechnology-derived therapeutic biologics over the last few decades has generated drugs that are now standard medical treatments for a range of indications. While the development of protein products has surged in recent years, the formulation and delivery of these complex molecules have relied on drug-specific studies and, in some instances, data from non-proteinaceous drug products. The commonalities, trends, and gaps in excipient technologies used to support the development of therapeutic proteins largely remain unexplored due to the drug-specific nature of many formulations. Using a comprehensive and relational database approach, we aimed to provide a scientific survey of all approved or licensed biotechnology-derived drug products with the goal of providing evidence-based information on common attributes and trending features in protein product excipients. We examined 665 formulations, and 395 unique formulations based on having unique excipients within them, that supported 211 therapeutic proteins as of June 2020. We report the prevalence of each excipient class and excipient chemical used in eight different drug types including monoclonal antibodies, antibody conjugates, cytokines and growth factors, enzymes, polypeptide hormones, pulmonary surfactants, recombinant fusion proteins, and toxins. We also report the prevalence by excipient type among all therapeutic proteins, in the context of each drug’s recommended pH range, concentration ranges for excipients, and route of administration. The results of our analyses indicate certain excipients common to monoclonal antibodies, cytokines, and polypeptide hormones. We also report on excipients unique to protein drug products, such as amino acids, solubilizers, and lyoprotectants. Overall, our report summarizes the current landscape of excipients used in marketed biotechnology-derived therapeutic biologic products.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Impacts of The Wetland Sedge Carex aquatilis on Microbial Community and Methane Metabolisms

Microbial activity in the soil of wetlands is responsible for the emission of more methane to the atmosphere than all other natural sources combined. This microbial activity is heavily impacted by plant roots, which influence the microbial community by exuding organic compounds and by leaking oxygen into an otherwise anoxic environment. This study compared the microbial communities of planted and unplanted wetland soil from an Alaskan bog to elucidate how plant growth influences populations and metabolisms of methanogens and methanotrophs. A common boreal wetland sedge, Carex aquatilis, was grown in the laboratory and DNA samples were sequenced from the rhizosphere, unplanted bulk soil, and a simulated rhizosphere with oxygen input but no organic carbon. The abundance of both methanogens and methanotrophs were positively correlated with methane emissions. Among the methanotrophs, both aerobic and anaerobic methane oxidizing microbes were more common in the rhizosphere of mature plants than in unplanted soil, while facultative methanotrophs capable of utilizing either methane or other molecules became relatively less common. Furthermore, these trends indicate that the roots in this experiment created an environment which favored highly specialized microbial metabolisms over generalist approaches. One aspect of this specialized microbiome is the presence of both aerobic and anaerobic metabolisms, which indicates that oxygen is present but is a limiting resource controlling competition.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

A fish-eye view of riverine hydropower systems. Understanding the biological response to turbine passage

One-way connectivity maintained by fish passing through hydropower turbines in fragmented rivers can be important to population dynamics, but can introduce a new and significant source of mortality due to turbine-associated mortality. Sources of mortality during downstream turbine passage can come from several sources including blade strike, shear forces, cavitation, or pressure decreases, and parsing the contributions of these individual forces is important for advancing and deploying turbines that minimize these impacts to fishes. We used a national hydropower database and conducted a systematic review of the literature to accomplish three goals: (1) report on the spatial distribution of turbine types and generation capacities in the USA, (2) determine fish mortality rates among turbine types and fish species and (3) examine relationships between physical forces similar to those encountered during fish turbine passage and fish injury and mortality. We found that while Francis turbines generate 56% of all US hydropower and have the highest associated fish mortality of any turbine type, these turbines are proportionally understudied compared to less-common and less injury-associated Kaplan turbines, particularly in the Pacific Northwest. While juvenile salmonid species in actual or simulated Kaplan turbine conditions were the most commonly studied, the highest mortality rates were reported in percid fishes passing through Francis turbines. Also, although there are several mechanisms of turbine-associated injury, barotrauma was the most commonly studied with swim bladder rupture, exopthalmia, eye gas bubbles, and prolapsed cloaca being the most serious symptoms associated with rapid pressure decreases. Future studies should focus on understanding which species are most at-risk to turbine passage mortality and, subsequently, increasing the diversity of taxonomy and turbine types in evaluations of turbine mortality.

13 HYDRO ENERGY↗
DOE OSTI2017

Occupant behavior models: A critical review of implementation and representation approaches in building performance simulation programs

Occupant behavior (OB) in buildings is a leading factor influencing energy use in buildings. Quantifying this influence requires the integration of OB models with building performance simulation (BPS). This study reviews approaches to representing and implementing OB models in today’s popular BPS programs, and discusses weaknesses and strengths of these approaches and key issues in integrating of OB models with BPS programs. Two of the key findings are: (1) a common data model is needed to standardize the representation of OB models, enabling their flexibility and exchange among BPS programs and user applications; the data model can be implemented using a standard syntax (e.g., in the form of XML schema), and (2) a modular software implementation of OB models, such as functional mock-up units for co-simulation, adopting the common data model, has advantages in providing a robust and interoperable integration with multiple BPS programs. Such common OB model representation and implementation approaches help standardize the input structures of OB models, enable collaborative development of a shared library of OB models, and allow for rapid and widespread integration of OB models with BPS programs to improve the simulation of occupant behavior and quantification of their impact on building performance.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2018

Is coronary calcium scoring too late? Total body arterial calcium burden in patients without known CAD and normal MPI

Background: Patients with normal myocardial perfusion imaging (MPI) have a good prognosis. However, pre-clinical coronary and extracoronary atherosclerosis may exist in the absence of myocardial ischemia. Methods: 154 Egyptian patients (mean age 53 years) underwent whole-body non-contrast CT following normal MPI. Results: Atherosclerosis in the form of calcification was observed in ≥1 vascular bed in 115 of 154 (75%) patients. This included the iliofemoral (62%), abdominal aorta (53%), thoracic aorta (47%), coronary (47%), and carotid (25%) vascular beds. Mean total body calcium score was 3172 ± 530 AU. Extracoronary atherosclerosis in patients with a zero coronary artery calcium (CAC) score was common, occurring in the above-listed beds 42%, 36%, 29%, and 7% of the time, respectively. CAC was rarely present without iliofemoral or abdominal aortic calcification. Conclusion: Quantitative assessment of calcification in different vascular beds demonstrates that extracoronary atherosclerosis is common in patients who have normal MPI. Atherosclerotic calcifications are most common in the iliofemoral arteries and abdominal aorta, which typically predate coronary calcifications. An imaging strategy to detect extracoronary atherosclerosis could lead to greater understanding of the natural history of atherosclerosis in its long pre-clinical phase and possibly to earlier preventive strategies.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Gas-Phase Chemistry in the GC Orbitrap Mass Spectrometer

Gas-phase reactions of temporally stored ions play a significant role in trapped ion mass spectrometry. Especially highly labile ion species generated through electron ionization (EI) are prone to undergo gas-phase reactions after relaxation to a low vibrational state. Here, we show that in the C-Trap of the Q Exactive GC Orbitrap mass spectrometer, gaseous water reacts with radical cations of various compound classes. High-resolution accurate mass spectrometry of the resulting ions provides a key to the mechanistic understanding of the chemistry of high energetic species generated during EI. We systematically addressed water adduct formation by use of H{sub 2}O and D{sub 2}{sup 18}O in the C-Trap. Mass spectra of halogen cyanides XCN (X=Cl, Br, I) showed the formation of HXCN{sup +} species, indicating hydrogen atomic transfer reactions. Relative ratios of HXCN{sup +}/XCN{sup +•} increased as the electronegativity of the halide increased. The common internal calibrant perfluorotributylamine forms oxygenated products from water reactive fragment ions. These can be explained by the addition of water to an initial cation followed by elimination of two HF molecules. This addition/elimination chemistry can also explain [M+2]{sup +} and [M+3]{sup +} ions that commonly occur in mass spectra of silylated analytes. High-resolution accurate mass spectra of trimethylsilyl (TMS) derivatives revealed these as [M−CH{sub 3}{sup •}+H{sub 2}O]{sup +} and [M−CH{sub 4}+H{sub 2}O]{sup •+}, respectively. This study explains common fragment ions in ion trap mass spectrometry. It also opens up perspectives for the systematic mechanistic and kinetic investigation of high-energy ion reactivity. .

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2018

Parallel iterative methods for a finite family of sequences of nearly nonexpansive mappings in Hilbert spaces

In this paper, we propose some new parallel iterative methods by the hybrid and shrinking projection to find a common fixed point of a finite family of sequences of nearly nonexpansive mappings in Hilbert spaces when the domain C satisfies diam(C) < ∞. We also give some applications of our main results for the problem of finding a common fixed point of nonexpansive mappings, nonexpansive semi-groups, the problem of finding a common zero point of monotone operators, the system of generalized mixed equilibrium problems and the system of variational inequalities without the condition diam(C) < ∞. Three numerical examples also are given to illustrate the effectiveness of the proposed algorithms.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2014

Preservation of the geometric quantum discord in noisy environments

Geometric description of quantum correlations is favored for their distinct physical significance. Geometric discords based on the trace distance and the Bures distance are shown to be well-defined quantum correlation measures. Here, we examine their particular dynamical behaviors under independent as well as common structured reservoirs and reveal their robustness against decoherence. We showed that the two well-defined geometric discords may be preserved well or even be improved and generated by the noisy process of the common reservoir. Moreover, we also provided a strategy for the long-time preservation of these two geometric discords in independent reservoirs. -- Highlights: •Inherent robustness of the trace distance and the Bures distance discord. •Generating geometric discord from classical states by the noisy process. •Improvement of the geometric discord in common reservoir. •The robust pathway for preserving discord in independent reservoirs.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2014

Sudden transition and sudden change from open spin environments

We investigate the necessary conditions for the existence of sudden transition or sudden change phenomenon for appropriate initial states under dephasing. As illustrative examples, we study the behaviors of quantum correlation dynamics of two noninteracting qubits in independent and common open spin environments, respectively. For the independent environments case, we find that the quantum correlation dynamics is closely related to the Loschmidt echo and the dynamics exhibits a sudden transition from classical to quantum correlation decay. It is also shown that the sudden change phenomenon may occur for the common environment case and stationary quantum discord is found at the high temperature region of the environment. Finally, we investigate the quantum criticality of the open spin environment by exploring the probability distribution of the Loschmidt echo and the scaling transformation behavior of quantum discord, respectively. - Highlights: • Sudden transition or sudden change from open spin baths are studied. • Quantum discord is related to the Loschmidt echo in independent open spin baths. • Steady quantum discord is found in a common open spin bath. • The probability distribution of the Loschmidt echo is analyzed. • The scaling transformation behavior of quantum discord is displayed.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2020

Reliability of emergency and standby diesel generators: Impact on energy resiliency solutions

Emergency diesel generators are the most common form of backup power for critical loads when the grid fails and are most often deployed as stand-alone generators (<2000 kW) tied to individual buildings for hospitals, emergency services, military bases, ports, airports, industries, and commercial facilities. Understanding the finite reliability of emergency diesel generators during continuous operation is critical for energy planners, managers, and end-users. A new analysis of two large non-public emergency diesel generator operational data sets shows that commonly used reliability metrics are inadequate to predict the performance during a grid outage. Additional metrics addressing the likelihood of an emergency diesel generator to be available at the time an outage starts, successfully start and carry load, and constantly run for the duration of the outage are needed to predict the continuous run-time reliability of emergency diesel generators during a grid outage. This is the first analysis of the reliability of modern generators that follow standard maintenance protocols commonly used for backup power and these new metrics are shown to be dependent on the level of emergency diesel generator maintenance with values that can vary by more than an order of magnitude. Even using the new metrics for well-maintained emergency diesel generators, the analysis shows that the single emergency diesel generators configurations are only 80% likely to provide power for the duration of a two-week grid outage.

ENERGY PLANNING, POLICY, AND ECONOMY,POWER TRANSMI↗
DOE OSTI2017

Efficacy of acetate-amended biostimulation for uranium sequestration: Combined analysis of sediment/groundwater geochemistry and bacterial community structure

Systematic flow-through column experiments were conducted using sediments and ground water collected from different subsurface localities at the U.S. Department of Energy's Integrated Field Research Challenge site in Rifle, Colorado. The principal purpose of this study is to gain a better understanding of the interactive effects of groundwater geochemistry, sediment mineralogy, and indigenous bacterial community structures on the efficacy of uranium removal from the groundwater with/without acetate amendment. Overall, we find that the subtle variations in the sediments' mineralogy, particle size, redox conditions, as well as contents of metal(loid) co-contaminants showed a pronounced effect on the associated bacterial population and composition, which mainly determines the system's performance with respect to uranium removal. Positive relationship was identified between the abundance of dissimilatory sulfate-reduction genes (i.e., drsA), markers of sulfatereducing bacteria, and the sediments' propensity to sequester aqueous uranium. In contrast, no obvious connections were observed between the abundance of common iron-reducing bacteria, e.g., Geobacter spp., and the sediments' ability to sequester uranium. In the sediments with low bacterial biomass and the absence of sulfate-reducing conditions, abiotic adsorption onto mineral surfaces such as phyllosilicates likely played a relatively major role in the attenuation of aqueous uranium; however, in these scenarios, acetate amendment induced detectable rebounds in the effluent uranium concentrations. The results of this study suggest that reductive immobilization of uranium can be achieved under predominantly sulfate-reducing conditions, and provide insight into the integrated roles of various biogeochemical components in long-term uranium sequestration.

58 GEOSCIENCES↗