Metal-Organic Framework Glass Anode with an Exceptional Cycling-Induced Capacity Enhancement for Lit
Explore the source record for details and available documents.
Gao, Chengwei↗
SEARCH · Search NASA
Results for “capacity enhancement”
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Energy storage solutions to decarbonize electricity through enhanced capacity expansion modelling
To meet ambitious global decarbonization goals, electricity system planning and operations will change fundamentally. With increasing reliance on variable renewable energy resources, energy storage is likely to play a critical accompanying role to help balance generation and consumption patterns. As grid planners, non-profit organizations, non-governmental organizations, policy makers, regulators and other key stakeholders commonly use capacity expansion modelling to inform energy policy and investment decisions, it is crucial that these processes capture the value of energy storage in energy-system decarbonization. Here we conduct an extensive review of literature on the representation of energy storage in capacity expansion modelling. We identify challenges related to enhancing modelling capabilities to inform decarbonization policies and electricity system investments, and to improve societal outcomes throughout the clean energy transition. Additionally, we further identify corresponding research activities that can help overcome these challenges and conclude by highlighting tangible real-world outcomes that will result from pursuing these research activities. Capacity expansion modelling (CEM) approaches need to account for the value of energy storage in energy-system decarbonization. A new Review considers the representation of energy storage in the CEM literature and identifies approaches to overcome the challenges such approaches face when it comes to better informing policy and investment decisions.
25 ENERGY STORAGE↗
Targeting the Bet-Hedging Strategy with an Inhibitor of Bacterial Efflux Capacity Enhances Antibiotic Efficiency and Ameliorates Bacterial Persistence In Vitro
Persistence is a bet-hedging strategy in bacterial populations that increases antibiotic tolerance and leads to the establishment of latent infections. In this study, we demonstrated that a synthetic non-toxic taxane-based reversal agent (tRA), developed as an inhibitor of ABC transporter systems in mammalian cancer cells, enhanced antibiotic killing of persister populations from different pathogens, including Burkholderia, Pseudomonas, Francisella, and Yersinia. Acting as an inhibitor of bacterial efflux at 100 nM, tRA99020 enhanced antibiotic efficiency and suppressed the production of natural products of Burkholderia species polyketide synthase (PKS) function. We demonstrate that the metabolites produced by PKS in response to stress by different antibiotics act as inhibitors of mammalian histone deacetylase activity and stimulate cell death. Applying a single-molecule fluorescence in situ hybridization (smFISH) assay, we analyzed on a single-cell level the activation profiles of the persistence regulating pks gene in Burkholderia thailandensis treated with tRA99020 and antibiotics. We posit that a multi-pronged approach encompassing antibiotic therapies and inhibition of efflux systems and fatty acid catabolism will be required for efficient eradication of persistent bacterial populations.
59 BASIC BIOLOGICAL SCIENCES↗
NASA Satellite-based Earth Observation Systems and Hydrological Modeling Enhance Capacity Building in the Lower Mekong River Basin
Explore the source record for details and available documents.
Ibrahim Mohammed↗
Development of a Wake Vortex Spacing System for Airport Capacity Enhancement and Delay Reduction
The Terminal Area Productivity project has developed the technologies required (weather measurement, wake prediction, and wake measurement) to determine the aircraft spacing needed to prevent wake vortex encounters in various weather conditions. The system performs weather measurements, predicts bounds on wake vortex behavior in those conditions, derives safe wake spacing criteria, and validates the wake predictions with wake vortex measurements. System performance to date indicates that the potential runway arrival rate increase with Aircraft VOrtex Spacing System (AVOSS), considering common path effects and ATC delivery variance, is 5% to 12% depending on the ratio of large and heavy aircraft. The concept demonstration system, using early generation algorithms and minimal optimization, is performing the wake predictions with adequate robustness such that only 4 hard exceedances have been observed in 1235 wake validation cases. This performance demonstrates the feasibility of predicting wake behavior bounds with multiple uncertainties present, including the unknown aircraft weight and speed, weather persistence between the wake prediction and the observations, and the location of the weather sensors several kilometers from the approach location. A concept for the use of the AVOSS system for parallel runway operations has been suggested, and an initial study at the JFK International Airport suggests that a simplified AVOSS system can be successfully operated using only a single lidar as both the weather sensor and the wake validation instrument. Such a selfcontained AVOSS would be suitable for wake separation close to the airport, as is required for parallel approach concepts such as SOIA.
Hinton, David A.↗
Template-Assisted, Seed-Mediated Synthesis of Hierarchically Mesoporous Core–Shell UiO-66: Enhancing Adsorption Capacity and Catalytic Activity through Iterative Growth
A hierarchically mesoporous (HM) UiO-66-F 4 shell with ~8 nm mesopores can be iteratively grown on top of UiO-66 nanoparticle (NP) seeds over several cycles templated by Pluronic F-127 micelles. Presumably, the Pluronic micelles that were formed in water can surround UiO-66 NPs to facilitate the overgrowth of an HM-UiO-66-F 4 shell in the presence of Zr IV precursors and BDC-F 4 linkers. The UiO-66 NP seeds play an important role in directing the continuous growth of the HM-UiO-66-F 4 shell, as only a nonporous phase was obtained in their absence. Furthermore, this template-assisted, seed-mediated method can be extended to produce other UiO-66-X (X = (OH) 2 , (COOH) 2 , etc.) shells, demonstrating its generality for the UiO-66 family of metal–organic frameworks. Notably, the incorporation of mesopores into the thrice-overgrown UiO-66@HM|3rd-UiO-66-F 4 materials leads to impressive enhancements in the per-mass uptake capacity of Direct Blue 86, a large anionic dye: 320% better than the parent UiO-66 seeds and 150% better than that for a [UiO-66 + UiO-66-F 4 ] physical mixture at the same mass proportion. Similar enhancements were also observed in the catalyzed oxidation of thioanisole.
36 MATERIALS SCIENCE↗
Underlying limitations behind impedance rise and capacity fade of single crystalline Ni-rich cathodes synthesized via a molten-salt route
Layered oxide LiNi x Mn y Co z O 2 (NMC) cathodes are often synthesized as polycrystalline secondary particles. Due to intergranular fracture stemming from volume changes of randomly oriented primary particles during charge/discharge, the synthesis of larger single-crystalline cathodes is of high interest. In this work, molten salt assisted growth of micron-sized Ni-rich crystals is achieved with excellent crystallinity, low cation mixing, and negligible impurities. However, electrochemical performance is compromised by high surface reactivity resulting in decomposition of electrolyte and subsequent formation of a thick CEI layer. While intergranular fracture is eliminated, planar gliding and severe intragranular fracture along the (003) plane occurs in the high voltage region within the first few cycles and is associated primarily with H2 to H3 structural transitions. In addition, H2 to H3 transitions are highly irreversible with cyclic voltammograms revealing polarization growth within <5 cycles. Subsequently, the single-crystalline material exhibited markedly reduced available capacity and enhanced capacity fade from sharp impedance growth compared to its polycrystalline counterpart. Here, this work furthers a fundamental understanding into the limitations of single-crystalline Ni-rich cathodes, and the obstacles limiting the advantages offered by the single-crystalline morphology.
25 ENERGY STORAGE↗
Impact of sodium vanadium oxide (NaV 3 O 8 , NVO) material synthesis conditions on charge storage mechanism in Zn-ion aqueous batteries
The electrochemical charge storage of sodium vanadate (NaV 3 O 8 or NVO) cathodes in aqueous Zn-ion batteries has been hypothesized to be influenced by the inclusion of structural water for facilitating ion transfer in the material. Materials properties considered important (morphology, crystallite and particle size, surface area) are systematically studied herein through investigation of two NVO materials, NaV 3 O 8 ·0.34H 2 O [NVO(300)] and NaV 3 O 8 ·0.05H 2 O [NVO(500)], with different water content, acicular morphologies with different size and surface area achieved via post-synthesis heat treatment. The electrochemistry of the two materials was evaluated in aqueous Zn-ion cells with 2 M ZnSO 4 electrolyte using cyclic voltammetry, galvanostatic cycling, and rate capability testing. Furthermore, the thinner NVO(300) nanobelts (0.13 μm) demonstrate greater specific capacities and higher effective diffusion coefficients relative to the thicker NVO(500) nanorods. Notably however, while cells containing NVO(500) deliver lower specific capacity, they demonstrate enhanced capacity retention with cycling. The structural changes accompanying oxidation and reduction are elucidated via ex situ X-ray diffraction, transmission electron microscopy, and operando V K-edge X-ray absorption spectroscopy (XAS), where NVO material properties are shown to influence the ion insertion. Operando XAS verified that electron transfer corresponds directly to change in vanadium oxidation state, affirming vanadium redox as the governing electrochemical process.
25 ENERGY STORAGE↗
Integration of a thermoelectric subcooler with an air‑source heat pump to enhance heating capacity and dehumidification
This study presents an innovative configuration of a thermoelectric subcooler (TES) integrated with an air-source heat pump (ASHP). The TES is installed in the liquid line, where it absorbs heat from the refrigerant. On its hot side, it discharges heat to the return air in heating mode or to the supply air in cooling mode, enabling year-round operation. The ASHP–TES system was evaluated under various conditions to reduce supplemental heating needs and improve dehumidification. Experimental heating tests revealed that activating the TES increased the heating capacity by 12%–20%. However, this occurred with a 7.6%–10% reduction in heating coefficient of performance (COP). In cooling mode, TES operation significantly improved moisture removal. The TES reduced the sensible heat ratio (SHR) and enhanced dehumidification, removing 20%–50% more moisture than a conventional system when meeting the same sensible load. The TES can be turned off to use the refrigerant subcooler for reheat supply air or turned on to substantially boost dehumidification. When meeting the same latent load, the ASHP–TES system achieved up to 33% energy savings compared with a conventional ASHP using resistance heating. Relative to a conventional ASHP paired with a whole-house dehumidifier, the ASHP–TES system provided up to 20% energy savings. These findings underscore the potential of TES integration to improve latent load control and enhance overall energy efficiency in hybrid ASHP systems, especially in cold and humid climates.
Hu, Yifeng [ORNL] (ORCID:0000000242875185)↗
Tablelike magnetocaloric effect and enhanced refrigerant capacity in EuO 1- δ thin films
The effect of electron doping of EuO 1- δ thin films through oxygen vacancies ( δ = 0, 0.025, and 0.09) upon the magnetocaloric response is presented here. The films each showed a paramagnetic to ferromagnetic transition around 65 K, with an additional magnetic ordering transition at higher temperatures in the oxygen deficient samples. All transitions are observed to be of second order. A maximum magnetic entropy change of 6.4 J/kg K over a field change of 2 T with a refrigerant capacity of 223 J/kg was found in the sample with δ = 0, and in all cases the refrigerant capacities of the thin films under study were found to exceed that reported for bulk EuO. Adjusting the oxygen content was shown to produce tablelike magnetocaloric effects, desirable for ideal Ericsson-cycle magnetic refrigeration. These films are thus excellent candidates for small-scale magnetic cooling technology in the liquid nitrogen temperature range.
36 MATERIALS SCIENCE↗
Long-term nitrogen deposition enhances microbial capacities in soil carbon stabilization but reduces network complexity
Background: Anthropogenic activities have increased the inputs of atmospheric reactive nitrogen (N) into terrestrial ecosystems, affecting soil carbon stability and microbial communities. Previous studies have primarily examined the effects of nitrogen deposition on microbial taxonomy, enzymatic activities, and functional processes. Here, we examined various functional traits of soil microbial communities and how these traits are interrelated in a Mediterranean type grassland administrated with 14 years of 7 g m –2 year –1 of N amendment, based on estimated atmospheric N deposition in areas within California, USA, by the end of the twenty-first century. Results: Soil microbial communities were significantly altered by N deposition. Consistent with higher aboveground plant biomass and litter, fast-growing bacteria, assessed by abundance-weighted average rRNA operon copy number, were favored in N deposited soils. The relative abundances of genes associated with labile carbon (C) degradation (e.g., amyA and cda) were also increased. In contrast, the relative abundances of functional genes associated with the degradation of more recalcitrant C (e.g., mannanase and chitinase) were either unchanged or decreased. Compared with the ambient control, N deposition significantly reduced network complexity, such as average degree and connectedness. The network for N deposited samples contained only genes associated with C degradation, suggesting that C degradation genes became more intensely connected under N deposition. Conclusions: We propose a conceptual model to summarize the mechanisms of how changes in above- and belowground ecosystems by long-term N deposition collectively lead to more soil C accumulation.
59 BASIC BIOLOGICAL SCIENCES↗
Enhanced Airport Capacity Through Safe, Dynamic Reductions in Aircraft Separation: NASA's Aircraft VOrtex Spacing System (AVOSS)
An aspect of airport terminal operations that holds potential for efficiency improvements is the separation criteria applied to aircraft for wake vortex avoidance. These criteria evolved to represent safe spacing under weather conditions conducive to the longest wake hazards, and are consequently overly conservative during a significant portion of operations. Under many ambient conditions, such as moderate crosswinds or turbulence, wake hazard durations are substantially reduced. To realize this reduction NASA has developed a proof-of-concept Aircraft Vortex Spacing System (AVOSS). Successfully operated in a real-time field demonstration during July 2000 at the Dallas Ft. Worth International Airport, AVOSS is a novel integration of weather sensors, wake sensors, and analytical wake prediction algorithms. Gains in airport throughput using AVOSS spacing as compared to the current criteria averaged 6%, with peak values approaching the theoretical maximum of 16%. The average throughput gain translates to 15-40% reductions in delay when applied to realistic capacity ratios at major airports.
OConnor, Cornelius J.↗
A cost–benefit framework to evaluate capacity upgrade options in overhead line transmission planning
This paper presents the methodology behind the new Reconductoring Economic and Financial Analysis (REFA) tool, an open-access software, used by transmission utilities to evaluate transmission capacity enhancement options. The proposed methodology is intended to be used in a new planning stage, after the capacity expansion and prior to the individual transmission project engineering, allowing capacity upgrade options (reconductoring, rebuild or voltage upgrade), and respective conductor selection, to be compared under the same economic basis. Furthermore, the REFA tool implements a methodology to rank project options and conductor types based on economic criteria, considering an approximation of the ampacity and sag constraints. Results, using 5 real transmission lines in the US, show that least-cost combinations of project and conductor types can be very diverse, which emphasizes the need for the proposed methodology and tool.
Advanced conductors↗
Encapsulated Sb and Sb 2 O 3 particles in waste-tire derived carbon as stable composite anodes for sodium-ion batteries
A conductive network of waste-tire derived carbon (WTC) was used to produce homogeneous Sb/WTC and Sb 2 O 3 /WTC composite materials via ball milling as promising anodes for sodium-ion batteries (SIBs). Highly reversible redox peaks at 0.81/0.71, 0.25 V for Sb/WTC and 0.80/0.76, 0.21/0.26 V for Sb 2 O 3 /WTC anodes have been observed related to Na + intercalation and deintercalation in carbon and Na–Sb and Na 3 Sb as plausible conversion/alloy reactions. Sodium half-cells delivered reversible discharge capacities of 206 mA h g -1 and 207 mA h g -1 at a current density of 37 mA g -1 for the composite Sb/WTC and Sb 2 O 3 /WTC materials, respectively. Both the Sb/WTC and Sb 2 O 3 /WTC composite materials showed impressive capacity retention with 85% and 88%, respectively after 100 cycles. Furthermore, rate capability studies at 60 °C yielded an enhanced capacity of 240 mA h g -1 for Sb/WTC and 300 mA h g -1 for Sb 2 O 3 /WTC at 37 mA g -1 .
25 ENERGY STORAGE↗
On Proper Selection of Multihop Relays for Future Enhancement of AeroMACS Networks
As the Aeronautical Mobile Airport Communications System (AeroMACS) has evolved from a technology concept to a deployed communications network over major US airports, it is now time to contemplate whether the existing capacity of AeroMACS is sufficient to meet the demands set forth by all fixed and mobile applications over the airport surface given the AeroMACS constraints regarding bandwidth and transmit power. The underlying idea in this article is to present IEEE 802.16j-based WiMAX as a technology that can address future capacity enhancements and therefore is most feasible for AeroMACS applications. The principal argument in favor IEEE 802.16j technology is the flexible and cost effective extension of radio coverage that is afforded by relay fortified networks, with virtually no increase in the power requirements and virtually no rise in interference levels to co-allocated applications. The IEEE 802.16j-based multihop relay systems are briefly described. The focus is on key features of this technology, frame structure, and its architecture. Next, AeroMACS is described as a WiMAX-based wireless network. The two major relay modes supported by IEEE 802.16j amendment, i.e., transparent and non-transparent are described. The benefits of employing multihop relays are listed. Some key challenges related to incorporating relays into AeroMACS networks are discussed. The selection of relay type in a broadband wireless network affects a number of network parameters such as latency, signal overhead, PHY (Scalable Physical Layer) and MAC (Media Access Layer) layer protocols, consequently it can alter key network quantities of throughput and QoS (Quality of Service).
aircraft communications↗
Electrodeposited Zinc-based Films as Anodes for Aqueous Zinc Batteries
Zinc-based batteries have attracted extensive attention in recent years, due to high safety, high capacities, environmental friendliness, and low cost compared to lithium ion batteries. However, the zinc anode suffers primarily from dendrite formation as a mode of failure in the mildly acidic system. Herein, we report on electrochemically deposited zinc (ED Zn) and copper-zinc (brass) alloy anodes, which are critically compared with a standard commercial zinc foil. The film electrodes are of commercially relevant thicknesses (21 and 25µM). The electrodeposited zinc-based anodes exhibit low electrode polarization (~0.025V) and stable cycling performance in 50 cycle consecutive experiments from 0.26-10 mA cm-2 compared to commercial Zn foil. Coulombic efficiencies at 1 mA cm-2 were over 98% for the electrodeposited zinc-based materials and were maintained for over 100 cycles. Furthermore, full cells with an electrodeposited Zn/brass anode, EMD MnO2 cathode, in 1M ZnSO4 + 0.1M MnSO4 delivered capacities of 96.3, and 163 mAh g-1, respectively, at a 100 mA g-1 compared to 92.1 mAh g-1 for commercial Zn. The zinc-based anodes also show better rate capability, delivering full cell capacities of 35.9 and 47.5 mAh g-1 at high current of up to 3 A g-1. Lastly, the electrodeposited zinc-based anodes show enhanced capacity for up to 100 cycles at 100 mA g-1, making them viable anodes for commercial use.
Fayette, Matthew R.↗