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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 1,189 records · Page 66
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Experimental and theoretical investigations of rotating algae biofilm reactors (RABRs): Areal productivity, nutrient recovery, and energy efficiency

Microalgae biofilms have been demonstrated to recover nutrients from wastewater and serve as biomass feedstock for bioproducts. However, there is a need to develop a platform to quantitatively describe microalgae biofilm production, which can provide guidance and insights for improving biomass areal productivity and nutrient uptake efficiency. Here, this paper proposes a unified experimental and theoretical framework to investigate algae biofilm growth on a rotating algae biofilm reactor (RABR). Experimental laboratory setups are used to conduct controlled experiments on testing environmental and operational factors for RABRs. We propose a differential–integral equation‐based mathematical model for microalgae biofilm cultivation guided by laboratory experimental findings. The predictive mathematical model development is coordinated with laboratory experiments of biofilm areal productivity associated with ammonia and inorganic phosphorus uptake by RABRs. The unified experimental and theoretical tool is used to investigate the effects of RABR rotating velocity, duty cycle (DC), and light intensity on algae biofilm growth, areal productivity, nutrient uptake efficiency, and energy efficiency in wastewater treatment. Our framework indicates that maintaining a reasonable light intensity range improves biomass areal productivity and nutrient uptake efficiency. Our framework also indicates that faster RABR rotation benefits biomass areal productivity. However, maximizing the nutrient uptake efficiency requires a reasonably low RABR rotating speed. Energy efficiency is strongly correlated with RABR rotating speed and DC.

09 BIOMASS FUELS↗
DOE OSTI2020

Additive-Free Formic Acid Dehydrogenation Using a Pincer- Supported Iron Catalyst

The iron complex ( iPr PN Me P)Fe(H) 2 (CO) ( iPr PN Me P = CH 3 N(CH 2 CH 2 P i Pr 2 ) 2 ), which features a pincer ligand with a tertiary amine, can give up to 100,000 turnovers for additive-free formic acid dehydrogenation (FADH). This is two orders of magnitude higher than any previously reported base metal system. Furthermore, mechanistic studies reveal the catalytic reaction pathway and provide guidance for the development of improved catalytic systems for additive-free FADH.

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

Electrocatalytic Effects of Au Nanoclusters in its Electrochemiluminescence Enhanced by Coreactant Tertiary Amines

Abstract Atomically precise metal nanoclusters are increasingly exploited in electrocatalysis such as water electrolysis and CO 2 reduction. The catalytic effects are generally evaluated by conventional electrochemical methods or end‐product analysis. Herein, near infrared electrochemiluminescence (ECL) of the nanoclusters is introduced as a new signaling mechanism to complement classical voltammetric analysis for elucidating essential electrocatalytic parameters. Coreactant ECL from an aqueous soluble Au 22 nanocluster (NCs) enhanced by a common pH buffer materials 4‐(2‐hydroxyethyl)‐1‐piperazineethanesulfonic acid (HEPES) and by a piperazine drug hydroxyzine (HDZ) is studied under oxidative reduction pathways. Foot of the wave analysis on voltametric features and the kinetics profiles in potential‐step experiments are studied in different nanocluster and coreactant concentrations. Benchmark parameters such as rate constants are determined under EC (Electron‐transfer‐Chemical‐reaction) mechanism as feasibility validations. Because the luminescence properties of AuNCs are sensitive to the surface ligands or adsorbents, ECL is proposed as a new signal readout for operando studies providing insights for governing reaction mechanism and kinetics during catalytic reactions. Retrospectively, mechanistic understanding of the complex multi‐step reactions during ECL generation can provide guidance for the evaluation and optimization of ECL property for better quantitative applications.

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

Uncovering the Critical Role of Ni on Surface Lattice Stability in Anionic Redox Active Li 1.2 Ni 0.2 Mn 0.6 O 2

Anionic redox reaction (ARR) can provide extra capacity beyond transition metal (TM) redox in lithium-rich TM oxide cathodes. Practical ARR application is much hindered by the structure instability, particularly at the surface. Oxygen release has been widely accepted as the ringleader of surficial structure instability. However, the role of TM in surface stability has been much overlooked, not to mention its interplay with oxygen release. Herein, TM dissolution and oxygen release are comparatively investigated in Li 1.2 Ni 0.2 Mn 0.6 O 2 . Ni is verified to detach from the lattice counter-intuitively despite the overwhelming stoichiometry of Mn, facilitating subsequent oxygen release of the ARR process. Intriguingly, surface reorganization occurs following regulated Ni dissolution, enabling the stabilization of the surface and elimination of oxygen release in turn. Accordingly, a novel optimization strategy is proposed by adding a relaxation step at 4.50 V within the first cycle procedure. Battery performance can be effectively improved, with voltage decay suppressed from 3.44 mV/cycle to 1.60 mV/cycle, and cycle stability improved from 66.77% to 90.01% after 100 cycles. This work provides new perspectives for clarifying ARR surface instability and guidance for optimizing ARR performance.

25 ENERGY STORAGE↗
DOE OSTI2022

Enhanced Carbon Capture Behavior of Carbon Fibers via Ionic Liquid Modification

Carbon-based materials are widely deployed in carbon capture but are only limited to physisorption procedures. Further extending functionalized carbon materials to CO 2 chemisorption under low CO 2 concentration is highly desirable yet challenging. In this study, a carbon fiber composed of solely ultra-micropores (~0.45 nm) was deployed as the precursor to avoid the pore blocking effect, which was modified by superbase-derived ionic liquids (ILs) containing strong interaction sites with CO 2 . By forming a thin coating layer on the surface, the as-afforded surface-functionalized fiber materials demonstrated enhanced CO 2 uptake capacity and improved CO 2 sorption kinetics, as evaluated by both the volumetric method and thermogravimetric analysis, as well as the calculated energy distribution curves. The achievements made in this work provide guidance on the functionalization of carbon-based materials towards enhanced CO 2 chemisorption by forming a thin layer of selected IL coating.

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

Deciphering the Evolution of Current Distribution in Hybrid Silver Vanadium Oxide / Carbon Monofluoride Cathodes within Lithium Primary Batteries

For batteries to function effectively all active material must be accessible requiring both electron and ion transport to each particle. A common approach to generating the needed conductive network is the addition of carbon to create a composite electrode. An alternative approach is the electrochemically induced formation of conductive reaction products where the electrochemically generated materials are in intimate contact with the active material contributing to effective connection of each active particle. Furthermore, this study probes silver vanadium oxide (Ag 2 V 4 O 11 , SVO), carbon monofluoride (CF x ), and hybrid SVO/CF x electrodes in lithium batteries. Ex situ XRD identifies Ag 0 as a reduction product from SVO and LiF from CF x that can be followed as a function of depth-of-discharge (DOD). Spatially-resolved operando energy dispersive x-ray diffraction reveals that the presence of SVO alleviates reaction heterogeneity in the electrodes which are electron transfer limited in the absence of sufficient Ag 0 . Synchrotron X-ray tomography on discharged cathodes reveals the distribution of silver particles where the particles are more closely spaced near the current collector indicating multiple nucleation sites for their formation. Finally, operando isothermal microcalorimetry is used to determine the heat dissipation of the parent and hybrid battery types. Using material enthalpy potentials, we determine the current distribution between the two active materials for the discharging hybrid cathode adding further insight to the diffraction analysis. Taken together, these results provide a comprehensive understanding of hybrid SVO/CF x cathodes and give guidance on optimal compositions that balance power and energy density considerations.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Methodology for Good Machine Learning with Multi‐Omics Data

In 2020, Novartis Pharmaceuticals Corporation and the U.S. Food and Drug Administration (FDA) started a 4‐year scientific collaboration to approach complex new data modalities and advanced analytics. The scientific question was to find novel radio‐genomics‐based prognostic and predictive factors for HR+/HER− metastatic breast cancer under a Research Collaboration Agreement. This collaboration has been providing valuable insights to help successfully implement future scientific projects, particularly using artificial intelligence and machine learning. This tutorial aims to provide tangible guidelines for a multi‐omics project that includes multidisciplinary expert teams, spanning across different institutions. We cover key ideas, such as “maintaining effective communication” and “following good data science practices,” followed by the four steps of exploratory projects, namely (1) plan, (2) design, (3) develop, and (4) disseminate. We break each step into smaller concepts with strategies for implementation and provide illustrations from our collaboration to further give the readers actionable guidance.

Pharmacology & Pharmacy↗
DOE OSTI2018

The Nature of the Long-Lived Excited State in a Ni II Phthalocyanine Complex Investigated by X-Ray Transient Absorption Spectroscopy

The nature of the photoexcited state of octabutoxy nickel(II) phthalocyanine (NiPcOBu8) with a 500ps lifetime was investigated by X-ray transient absorption (XTA) spectroscopy. Previous optical, vibrational, and computational studies have suggested that this photoexcited state has a ligand-to-metal charge transfer (LMCT) nature. By using XTA, which provides unambiguous information on the local electronic and nuclear configuration around the Ni center, the nature of the excited state of NiPcOBu8 was reassessed. Using X-ray probe pulses from a synchrotron source, the ground- and excited-state X-ray absorption spectra of NiPcOBu 8 were measured. Based on the results, we identified that the excited state exhibits spectral features that are characteristic of a Ni-1,Ni-3(3d(z2),3d(x2-y2)) state rather than a LMCT state with a transiently reduced Ni center. This state resembles the (d,d) state of nickel(II) tetramesitylphorphyrin. The XTA features are rationalized based on the inherent cavity sizes of the macrocycles. These results may provide useful guidance for the design of photocatalysts in the future.

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

Preparation, Properties, and Application of Lignocellulosic-Based Fluorescent Carbon Dots

We report that carbon dots (CDs) are a relatively new type of fluorescent carbon material with excellent performance and widespread application. As the most readily available and widely distributed biomass resource, lignocellulosics are a renewable bioresource with great potential. Research into the preparation of CDs with lignocellulose (LC-CDs) has become the focus of numerous researchers. Compared with other carbon sources, lignocellulose is low cost, rich in structural variety, exhibits excellent biocompatibility, and the structures of CDs prepared by lignin, cellulose, and hemicellulose are similar. This Review summarized research progress in the preparation of CDs from lignocellulosics in recent years and reviewed traditional and new preparation methods, physical and chemical properties, optical properties, and applications of LC-CDs, providing guidance for the formation and improvement of LC-CDs. In addition, the challenges of synthesizing LC-CDs were also highlighted, including the interaction of different lignocellulose components on the formation of LC-CDs and the nucleation and growth mechanism of LC-CDs; from this, current trends and opportunities of LC-CDs were examined, and some research methods for future research were put forward.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

High-Performance CO 2 Capture from Air by Harnessing the Power of CaO- and Superbase-Ionic-Liquid-Engineered Sorbents

Direct air capture (DAC) of CO 2 by solid porous materials represents an attractive “negative emission” technology. However, state-of-the-art sorbents based on supported amines still suffer from unsolved high energy consumption and stability issues. For this work, taking clues from the CO 2 interaction with superbase-derived ionic liquids (SILs), high-performance and tunable sorbents in DAC of CO 2 was developed by harnessing the power of CaO- and SIL-engineered sorbents. Deploying mesoporous silica as the substrate, a thin CaO layer was first introduced to consume the surface-OH groups, and then active sites with different basicities (e. g., triazolate and imidazolate) were introduced as a uniformly distributed thin layer. The as-obtained sorbents displayed high CO 2 uptake capacity via volumetric (at 0.4 mbar) and breakthrough test (400 ppm CO 2 source), rapid interaction kinetics, facile CO 2 releasing, and stable sorption/desorption cycles. Operando diffuse reflectance infrared Fourier transformation spectroscopy (DRIFTS) analysis under simulated air atmosphere and solid-state NMR under 13 CO 2 atmosphere demonstrated the critical roles of the SIL species in low-concentration CO 2 capture. The fundamental insights obtained in this work provide guidance on the development of high-performance sorbents in DAC of CO 2 by leveraging the combined advantages of porous solid scaffolds and the unique features of CO 2 -philic ionic liquids.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Cougar response to a gradient of human development

Abstract Human populations continue to increase and transform Earth's ecosystems. For large carnivores, human development reduces habitat abundance, alters predator–prey dynamics, and increases the risk of mortality, which may threaten the viability of many populations. To investigate how the cougar ( Puma concolor ) responds to a gradient of human development in four areas in Washington, USA, we used utilization distributions, county tax parcel data, Weibull modeling analysis, and multiple comparison techniques. Cougars used wildland areas the majority of the time (79% ± 2%, n = 112 cougars), with use decreasing as housing densities increased. When present in human‐developed areas in eastern Washington, 99% of the habitat that cougars used had housing densities ≤76.5 residences/km 2 , which was <846.0 residences/km 2 observed in western Washington ( P < 0.01). Cougars used areas in western Washington with greater housing density likely because of the clustered nature of housing developments, the connectivity with greenbelts and forested corridors, and security cover of dense maritime vegetation. Our findings suggest a consistent, albeit nuanced response by cougars to human development that may be used by wildlife managers, landscape planners, and environmental educators to guide and enhance their efforts to minimize the impacts of human development on cougars and reduce the potential for conflicts with people. Our model may also provide guidance for thresholds of human development for other adaptable large carnivores.

Washington↗
DOE OSTI2023

Conducting Polymers Meet Lithium–Sulfur Batteries: Progress, Challenges, and Perspectives

Lithium–sulfur (Li–S) batteries have attracted increased interest because of the high theoretical energy density, low cost, and environmental friendliness. Conducting polymers (CPs), as one of the most promising materials used in Li–S batteries, can not only facilitate electron transfer and buffer the large volumetric change of sulfur benefiting from their porous structure and excellent flexibility, but also enable stronger physical/chemical adsorption capacity toward polysulfides (LiPSs) when doped with abundant heteroatoms to promote the sulfur redox kinetics and achieve the high sulfur loading. This review firstly introduces the properties of various CPs including structural CPs (polypyrrole (PPy), polyaniline (PANi), polyethylene dioxothiophene [PEDOT]) and compound CPs (polyethylene oxide (PEO), polyvinyl alcohol (PVA) and poly(acrylic acid) [PAA]), and their application potential in Li–S batteries. Furthermore, the research progress of various CPs in different components (cathode, separator, and interlayer) of Li–S batteries is systematically summarized. Finally, the application perspective of the CPs in Li–S batteries as a potential guidance is comprehensively discussed.

Chen, Xin↗
DOE OSTI2023

Treatment of cholinergic‐induced status epilepticus with polytherapy targeting GABA and glutamate receptors

Abstract Despite new antiseizure medications, the development of cholinergic‐induced refractory status epilepticus (RSE) continues to be a therapeutic challenge as pharmacoresistance to benzodiazepines and other antiseizure medications quickly develops. Studies conducted by Epilepsia . 2005;46:142 demonstrated that the initiation and maintenance of cholinergic‐induced RSE are associated with trafficking and inactivation of gamma‐aminobutyric acid A receptors (GABA A R) thought to contribute to the development of benzodiazepine pharmacoresistance. In addition, Dr. Wasterlain's laboratory reported that increased N‐methyl‐ d ‐aspartate receptors (NMDAR) and alpha‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid receptors (AMPAR) contribute to enhanced glutamatergic excitation ( Neurobiol Dis . 2013;54:225; Epilepsia . 2013;54:78). Thus, Dr. Wasterlain postulated that targeting both maladaptive responses of reduced inhibition and increased excitation that is associated with cholinergic‐induced RSE should improve therapeutic outcome. We currently review studies in several animal models of cholinergic‐induced RSE that demonstrate that benzodiazepine monotherapy has reduced efficacy when treatment is delayed and that polytherapy with drugs that include a benzodiazepine (eg midazolam and diazepam) to counter loss of inhibition, concurrent with an NMDA antagonist (eg ketamine) to reduce excitation provide improved efficacy. Improved efficacy with polytherapy against cholinergic‐induced seizure is demonstrated by reduction in (1) seizure severity, (2) epileptogenesis, and (3) neurodegeneration compared with monotherapy. Animal models reviewed include pilocarpine‐induced seizure in rats, organophosphorus nerve agent (OPNA)‐induced seizure in rats, and OPNA‐induced seizure in two mouse models: (1) carboxylesterase knockout (Es1 −/− ) mice which, similarly to humans, lack plasma carboxylesterase and (2) human acetylcholinesterase knock‐in carboxylesterase knockout (KIKO) mice. We also review studies showing that supplementing midazolam and ketamine with a third antiseizure medication (valproate or phenobarbital) that targets a nonbenzodiazepine site rapidly terminates RSE and provides further protection against cholinergic‐induced SE. Finally, we review studies on the benefits of simultaneous compared with sequential drug treatments and the clinical implications that lead us to predict improved efficacy of early combination drug therapies. The data generated from seminal rodent studies of efficacious treatment of cholinergic‐induced RSE conducted under Dr. Wasterlain's guidance suggest that future clinical trials should treat the inadequate inhibition and temper the excess excitation that characterize RSE and that early combination therapies may provide improved outcome over benzodiazepine monotherapy.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2015

Radio-guided occult lesion localisation using iodine 125 Seeds “ROLLIS” to guide surgical removal of an impalpable posterior chest wall melanoma metastasis

Cancer screening and surveillance programmes and the use of sophisticated imaging tools such as positron emission tomography-computed tomography (PET-CT) have increased the detection of impalpable lesions requiring imaging guidance for excision. A new technique involves intra-lesional insertion of a low-activity iodine-125 ({sup 125}I) seed and detection of the radioactive signal in theatre using a hand-held gamma probe to guide surgery. Whilst several studies describe using this method to guide the removal of impalpable breast lesions, only a handful of publications report its use to guide excision of lesions outside the breast. We describe a case in which radio-guided occult lesion localisation using an iodine 125 seed was used to guide excision of an impalpable posterior chest wall metastasis detected on PET-CT.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Definition and visualisation of regions of interest in post-prostatectomy image-guided intensity modulated radiotherapy

Standard post-prostatectomy radiotherapy (PPRT) image verification uses bony anatomy alignment. However, the prostate bed (PB) moves independently of bony anatomy. Cone beam computed tomography (CBCT) can be used to soft tissue match, so radiation therapists (RTs) must understand pelvic anatomy and PPRT clinical target volumes (CTV). The aims of this study are to define regions of interest (ROI) to be used in soft tissue matching image guidance and determine their visibility on planning CT (PCT) and CBCT. Published CTV guidelines were used to select ROIs. The PCT scans (n = 23) and CBCT scans (n = 105) of 23 post-prostatectomy patients were reviewed. Details on ROI identification were recorded. Eighteen patients had surgical clips. All ROIs were identified on PCTs at least 90% of the time apart from mesorectal fascia (MF) (87%) due to superior image quality. When surgical clips are present, the seminal vesicle bed (SVB) was only seen in 2.3% of CBCTs and MF was unidentifiable. Most other structures were well identified on CBCT. The anterior rectal wall (ARW) was identified in 81.4% of images and penile bulb (PB) in 68.6%. In the absence of surgical clips, the MF and SVB were always identified; the ARW was identified in 89.5% of CBCTs and PB in 73.7%. Surgical clips should be used as ROIs when present to define SVB and MF. In the absence of clips, SVB, MF and ARW can be used. RTs must have a strong knowledge of soft tissue anatomy and PPRT CTV to ensure coverage and enable soft tissue matching.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

Validation of Spawn Checks and Saltwater Age Assignments Based on Scales from Known Repeat-Spawning Steelhead

Abstract It is critical to resolve the effects of regeneration, false annuli, and resorption on interpretation of scale patterns. We used scales collected from known repeat-spawning steelhead Oncorhynchus mykiss from the Snake River to (1) determine the accuracy of spawn check identification and (2) investigate errors in assignment of saltwater ages before and after spawn checks. Scale readers (n = 4) accurately identified over 96% of known repeat spawners (n = 107) and did not identify spawn checks in known first-time spawners (n = 197). Scale resorption associated with the spawn check caused an obscured or lost saltwater annulus in 66% of samples, most frequently in fish that spent 2 years versus 1 year in saltwater. Presence or absence of an annulus after the spawn check was accurately assigned in 86% of samples (n = 100). The potential for scale resorption to affect interpretation of the life history of iteroparous anadromous salmonids is significant. We supply two examples of how circulus counts can provide guidance to scale readers, but this analysis should be customized to the growth characteristics of each stock of interest.

Copeland, Timothy↗
DOE OSTI2018

A Review of Approaches for Monitoring the Effectiveness of Regional River Habitat Restoration Programs

Abstract Large regional programs to restore riverine habitat for fish and aquatic organisms have become common throughout North America, Europe, and elsewhere. Evaluating the effectiveness of projects implemented under these programs—sometimes called programmatic monitoring and evaluation—has proven challenging, and little guidance exists on programmatic monitoring and evaluation approaches and their effectiveness. In this paper, we review different approaches for evaluating the effectiveness of river restoration projects implemented across a region. These programmatic monitoring and evaluation approaches include case studies, meta-analyses, multiple before–after control–impact (mBACI), extensive posttreatment (EPT), intensively monitored watersheds (IMWs), and hybrid programmatic approaches that use a combination of different experimental designs. For each approach, we discuss the pros and cons as well as provide examples. The most appropriate approach depends in part on the questions that the programmatic monitoring and evaluation strives to address, the spatial and temporal scale at which detection of a response is expected, and the scale of inference. Case studies and mBACI approaches can answer questions about individual projects but have several limitations in terms of cost, timely results, and feasibility. A meta-analysis, which can provide broadly applicable results, is dependent upon a large number of case studies being completed. The EPT approach can provide relatively quick and easy-to-interpret results, but it requires a large population of completed projects and careful selection of controls. The IMW approach has been broadly applied in western North America but has had limited success and appears to be tractable only in small catchments where restoration and monitoring can be well controlled. Based on results from recent efforts in the USA and Europe, the most feasible programmatic monitoring and evaluation approach in terms of cost, implementability, and production of timely results appears to be a hybrid approach that uses a combination of the EPT and mBACI approaches.

Roni, Philip↗
DOE OSTI2019

Degradation in photovoltaic encapsulant transmittance: Results of the first PVQAT TG5 artificial weathering study

Reduced optical transmittance of encapsulants resulting from ultraviolet (UV) degradation is frequently identified as a cause of decreased performance through the service life of photovoltaic modules. However, the present module safety and qualification standards apply short UV doses, only capable of examining design robustness and 'infant mortality' failures. Furthermore, essential information remains unknown that might be used to screen encapsulants through product lifetime. We conducted an interlaboratory study to provide the understanding that will be used toward developing a higher-fidelity, more-rigorous UV weathering test. Five representative known formulations of poly (ethylene-co-vinyl acetate) were studied, in addition to one thermoplastic polyurethane material. Replicate laminated silica/polymer/silica specimens were examined at seven institutions using a variety of indoor chambers (including xenon, UVA-340, and metal-halide light sources). Specimens were artificially weathered for 180 cumulative days at steady-state accelerated test conditions, predesignated relative to the default irradiance of 1.0 W m-2 nm-1 at 340 nm, chamber temperature of 60 degrees C, and chamber relative humidity of 30%. The solar-weighted transmittance, yellowness index, and the UV cut-off wavelength - each determined from the measured hemispherical transmittance - are examined to provide understanding and guidance for the UV light source (type lamp and filters), temperature, and humidity used in accelerated UV aging tests. The relative efficacy of xenon-arc and UVA-340 fluorescent sources and the typical range of activation energy for degradation is quantified from the experiments.

14 SOLAR ENERGY↗