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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 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Tuning Internal Strain in Metal–Organic Frameworks via Vapor Phase Infiltration for CO 2 Reduction

Abstract A gas‐phase approach to form Zn coordination sites on metal–organic frameworks (MOFs) by vapor‐phase infiltration (VPI) was developed. Compared to Zn sites synthesized by the solution‐phase method, VPI samples revealed approximately 2.8 % internal strain. Faradaic efficiency towards conversion of CO 2 to CO was enhanced by up to a factor of four, and the initial potential was positively shifted by 200–300 mV. Using element‐specific X‐ray absorption spectroscopy, the local coordination environment of the Zn center was determined to have square‐pyramidal geometry with four Zn−N bonds in the equatorial plane and one Zn‐OH 2 bond in the axial plane. The fine‐tuned internal strain was further supported by monitoring changes in XRD and UV/Visible absorption spectra across a range of infiltration cycles. The ability to use internal strain to increase catalytic activity of MOFs suggests that applying this strategy will enhance intrinsic catalytic capabilities of a variety of porous materials.

Yang, Fan↗
DOE OSTI2018

Long non-coding RNA EPIC1 promotes human lung cancer cell growth

Highlights: • Lnc-EPIC1 expression is elevated in human lung cancer cells and tissues. • Lnc-EPIC1 siRNA inhibits lung cancer cell growth, but inducing cell cycle arrest and apoptosis. • MYC is the primary target of Lnc-EPIC1 in lung cancer cells. • Lnc-EPIC1 overexpression promotes lung cancer cell growth. Long non-coding RNA (LncRNA) EPIC1 (Lnc-EPIC1) is a MYC-interacting LncRNA. In the present study, the expression and potential function of Lnc-EPIC1 in human lung cancer cells are tested. We show that Lnc-EPIC1 expression is significantly higher in established/primary human lung cancer cells than that in human lung epithelial cells. Lnc-EPIC1 is also elevated in human lung cancer tissues. Silencing of Lnc-EPIC1 by targeted siRNA significantly inhibited human lung cancer cell growth, survival and proliferation, whiling inducing G1-S cell cycle arrest and cell apoptosis. MYC targets, including Cyclin A1, CDC20 and CDC45, were downregulated by Lnc-EPIC1 siRNA. MYC knockout by CRISPR/Cas-9 gene-editing method mimicked actions by Lnc-EPIC1 siRNA in A549 cells. Conversely, forced overexpression of Lnc-EPIC1 by a lentiviral construct increased expression of MYC targets to promote A549 cell growth. Lnc-EPIC1 directly associated with MYC protein in the nuclei of A549 cells. Significantly MYC knockout abolished Lnc-EPIC1 silencing- or overexpression-induced actions in human lung cancer cells. Together, our results show that Lnc-EPIC1 promotes human lung cancer cell growth possibly by targeting MYC.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

A novel solid oxide electrolytic cell with reduced endothermic load for CO 2 electrolysis using (La 0.80 Sr 0.20 ) 0.95 MnO 3-δ cathode

CO 2 conversion to CO via solid oxide electrolysis provides a potentially efficient method for converting CO 2 into an industrially relevant product. A solid oxide electrolysis cell with (La 0.80 Sr 0.20 ) 0.95 MnO 3-δ (LSM) as the CO 2 reduction cathode, yttrium stabilized zirconia (YSZ) as electrolyte, and nickel as the H 2 oxidation anode was operated 800 °C and 850 °C. Thermogravimetric analysis of the LSM material showed no catalyst oxidation at operating temperatures allowing for CO 2 electrolysis without reducing safe gas. In addition, no cathode material mass gain was observed in the presence of CO suggesting little to no carbon deposition occurred above 750 °C. The formation rates of CO for the cell reached 1.15 mL∙min-1∙ cm -2 for an applied current of 150 mA∙cm -2 achieving a faradaic efficiency of 100 %. Furthermore, the cell displayed good stability in the short-term CO 2 electrolysis test with a nominal voltage drop of 4 mV h -1 for 10 h at 850°C. This study shows the feasibility of operating a solid oxide CO 2 electrolysis cell for CO production with H 2 at the anode to reduce endothermic process load.

(La0.80Sr0.20)0.95MnO3-δ↗
DOE OSTI2018

Enhancement in Open-Circuit Voltage in Organic Solar Cells by Using Ladder-Type Nonfullerene Acceptors

The open-circuit voltage (V oc ) loss has always been a major factor in lowering power conversion efficiencies (PCEs) in bulk heterojunction organic photovoltaic cells (OPVs). A method to improve the V oc is indispensable to achieve high PCEs. Here in this paper, we investigated a series of perylene diimide-based ladder-type molecules as electron acceptors in nonfullerene OPVs. The D-A ladder-type structures described here lock our pi-systems into a planar structure and eliminate bond twisting associated with linear conjugated systems. This enlarges the interface energy gap (ΔE DA ), extends electronic delocalization, and hence improves the V oc . More importantly, these devices showed an increase in V oc without compromising either the J sc or the FF. C5r exhibited a strong intermolecular interaction and a PCE value of 6.1%. Moreover, grazing-incident wide-angle X-ray scattering analysis and atomic force microscopy images suggested that our fused-ring acceptors showed a suitable domain size and uniform blend films, which were not affected by their rigid molecular structures.

25 ENERGY STORAGE↗
DOE OSTI2025

Shake-Down Spectroscopy as State- and Site-Specific Probe of Ultrafast Chemical Dynamics

Tracking the multifarious ultrafast electronic and structural changes occurring in a molecule during a photochemical transformation is a challenging endeavor that benefits from recent experimental and computational progress in time-resolved techniques. Measurements of valence electronic states, which provide a global picture of the bonding structure of the molecule, and core electronic states, which provide insight into the local environment, traditionally require different approaches and are often studied separately. Here, we demonstrate that X-ray pulses from a seeded free-electron laser (FEL) enable the measurement of high-resolution, time-resolved X-ray photoelectron spectra (XPS) that capture weak satellite states resulting from shake-down processes in a valence-excited molecule. This approach effectively combines the advantages of both valence- and core-state investigations. We applied this method to investigate photoexcited CS2 molecules, where the role of internal conversion (IC) and intersystem crossing (ISC) in determining the predissociation dynamics is controversial. We present XPS spectra from photoexcited CS2, obtained at the FERMI FEL. High-resolution measurements, compared to the corresponding spectra obtained from accurate multireference quantum chemical calculations, reveal that shake-down satellite channels are highly sensitive to both valence electronic and geometric changes. Previous studies of the predissociation dynamics have led to uncertain assignments of the branching between singlet and triplet excited states. We derive a propensity rule that demonstrates the spin-selectivity of the shake-downs. This selectivity allows us to unequivocally assign contributions from the bright and dark singlet excited states, with populations tracked along the predissociation dynamic pathway.

Thompson, Henry J. [Univ. of Southampton (United K↗
DOE OSTI2024

Rapid advances enabling high-performance inverted perovskite solar cells

Perovskite solar cells (PSCs) that have a positive–intrinsic–negative (p–i–n, or often referred to as inverted) structure are becoming increasingly attractive for commercialization owing to their rapid increase in power conversion efficiency, easily scalable fabrication, reliable operation and compatibility with various perovskite-based tandem device configurations. In this report we review key material and device considerations for making highly efficient and stable p–i–n PSCs. First, we summarize key advances in charge transport materials, which were critical to the rapid power conversion efficiency progress. Second, we discuss promising perovskite compositions and fabrication methods. We highlight various additive engineering approaches to improve the perovskite layer as well as interface engineering strategies that target either the buried or top perovskite surface layer. Third, we review progress in tandem devices, focusing on optimization of the interconnection layer. Next, we summarize the status and strategies for improving p–i–n PSC stability, especially considering the challenges of outdoor applications. We also provide prospects for future research directions and challenges.

14 SOLAR ENERGY↗
DOE OSTI2017

Understanding inks for porous-electrode formation

Scalable manufacturing of high-aspect-ratio multi-material electrodes are important for advanced energy storage and conversion systems. Such technologies often rely on solution-based processing methods where the active material is dispersed in a colloidal ink. To date, ink formulation has primarily focused on macro-scale process-specific optimization (i.e. viscosity and surface/interfacial tension), and been optimized mainly empirically. Thus, there is a further need to understand nano- and mesoscale interactions and how they can be engineered for controlled macroscale properties and structures related to performance, durability, and material utilization in electrochemical systems.

42 ENGINEERING↗
DOE OSTI2019

Fantasy versus reality in fragment-based quantum chemistry

Since the introduction of the fragment molecular orbital method 20 years ago, fragment-based approaches have occupied a small but growing niche in quantum chemistry. These methods decompose a large molecular system into subsystems small enough to be amenable to electronic structure calculations, following which the subsystem information is reassembled in order to approximate an otherwise intractable supersystem calculation. Fragmentation sidesteps the steep rise (with respect to system size) in the cost of ab initio calculations, replacing it with a distributed cost across numerous computer processors. Such methods are attractive, in part, because they are easily parallelizable and therefore readily amenable to exascale computing. As such, there has been hope that distributed computing might offer the proverbial “free lunch” in quantum chemistry, with the entrée being high-level calculations on very large systems. While fragment-based quantum chemistry can count many success stories, there also exists a seedy underbelly of rarely acknowledged problems. As these methods begin to mature, it is time to have a serious conversation about what they can and cannot be expected to accomplish in the near future. Both successes and challenges are highlighted in this Perspective.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2022

Power Converter Circuit Design Automation using Parallel Monte Carlo Tree Search

The tidal waves of modern electronic/electrical devices have led to increasing demands for ubiquitous application-specific power converters. A conventional manual design procedure of such power converters is computation- and labor-intensive, which involves selecting and connecting component devices, tuning component-wise parameters and control schemes, and iteratively evaluating and optimizing the design. To automate and speed up this design process, we propose an automatic framework that designs custom power converters from design specifications using Monte Carlo Tree Search. Specifically, the framework embraces the upper-confidence-bound-tree (UCT), a variant of Monte Carlo Tree Search, to automate topology space exploration with circuit design specification-encoded reward signals. Moreover, our UCT-based approach can exploit small offline data via the specially designed default policy and can run in parallel to accelerate topology space exploration. Further, it utilizes a hybrid circuit evaluation strategy to substantially reduce design evaluation costs. Empirically, we demonstrated that our framework could generate energy-efficient circuit topologies for various target voltage conversion ratios. Compared to existing automatic topology optimization strategies, the proposed method is much more computationally efficient --- the sequential version can generate topologies with the same quality while being up to 67% faster. Here, the parallelization schemes can further achieve high speedups compared to the sequential version.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2022

Improving Ni-Based SOFC Anode Resilience and Durability through Secondary Phase Formation

The project used a multi-disciplinary approach to test test if 2° materials, added to traditional cermet components, enhanced SOFC mechanical strength, anode resilience and durability when subjected to electrochemical and environmental redox cycling. Findings from fracture testing, electrochemical studies and operando Raman spectroscopy measurements demonstrated that aluminum titanate (Al 2 TiO 5 or ALT) mechanically mixed with NiO-YSZ cermets confers superior mechanical strength and slower degradation rates under polarization. No deleterious effects from ALT in conversion efficiency were observed. Specific accomplishments included the following: (1) Refined methods used to fabricate ALT enhanced anodes into bi-layer anode supports to achieve high power densities; (2) Compared the effects of adding ALT mechanically to Ni-YSZ powders prior to anode fabrication with adding ALT through infiltration and co-infiltration of YSZ scaffolds; (3) Tested the resilience of these novel materials to electrochemical and environmental redox cycling and thermal stresses commonly encountered in functioning SOFCs; and (4) Characterized the ability of ALT to improve the carbon tolerance of Ni-YSZ anodes operating with dry methane.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2022

III-V Solar Cells with Novel Epitaxial Lift-off Architectures for Extended Substrate Reuse for Low-cost Manufacturing

The highest solar cell efficiencies have been achieved with III-V photovoltaics (PV). Still, the use of III-V materials in terrestrial applications has been very limited, mainly because of their high cost. The high cost is primarily due to the expensive Ge or GaAs wafers which could amount up to one-half of the total module cost! A prominent approach to reduce the impact of the high cost of substrates used for III-V PV is through re-use of the wafer substrates by Epitaxial Lift-Off (ELO). Typically, using a sacrificial layer such as AlAs, the device part of the cell is lifted off, leaving behind the substrate for re-use for fabrication of the next device. While conversion efficiency as high as 29.1% has been achieved by ELO method, chemical mechanical polishing (CMP) of the substrate is required which significantly adds to the overall solar cell cost. In this project, we have developed a novel ELO architecture for single junction gallium arsenide (GaAs) solar cells that will not require CMP of the substrate for re-use. Multiple reuses of GaAs wafers have been demonstrated with no CMP, without degradation in solar cell efficiency. Also, the solar cells have been successfully lifted off and transferred to inexpensive substrates with less than 2% change in efficiency. By elimination of the CMP process, which is the highest cost component of III-V solar cells made by conventional ELO method (~$10/W), and decreasing the substrate cost by multiple re-uses, the developed technology could be a leap forward in significantly reducing the cost of III-V photovoltaics.

14 SOLAR ENERGY↗
DOE OSTI2026

The Effects of Beta Irradiation on the Performance of ATR Fiber Probes

The use of real-time inline monitoring to track the chemical composition of slurries is recognized as a promising method to reduce the processing time of Hanford tank waste. The conversion of waste into glass suitable for long-term storage requires adherence to waste acceptance criteria and process control limits that respectively ensure safe operation of the vitrification facility and suitable glass quality. Real-time measurements of blended waste materials can ensure that the various criteria are met or can be addressed in a timely manner.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2025

Technology & Design Innovations to Maximize the Reduction Effect on DCFC Unit Cost Economics (Max‐REDUCE)

With the high cost and reliability issues of DCFC infrastructure the project specifically addressed the needs of innovating on the AC to DC power conversion. We proved the integration of a new power module into existing charger units, and that theoretical educational work on single stage energy conversion is commercially viable, and a reduced cost compared to existing methods. Our A sample shown 3 PH 480VAC 60hz to 350VDC 8.5kW power transfer, and our software and simulation proved efficiency greater than 97% from 20kW to > 60kW, over the DC output voltage range 200 – 1200V. The project was stopped before we could implement B sample and execute full power testing, validation and integration into a demonstration charger (budget period 3).

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2016

SU-F-T-64: An Alternative Approach to Determining the Reference Air-Kerma Rate from Extrapolation Chamber Measurements

Purpose: Since 2008 the Physikalisch-Technische Bundesanstalt (PTB) has been offering the calibration of {sup 125}I-brachytherapy sources in terms of the reference air-kerma rate (RAKR). The primary standard is a large air-filled parallel-plate extrapolation chamber. The measurement principle is based on the fact that the air-kerma rate is proportional to the increment of ionization per increment of chamber volume at chamber depths greater than the range of secondary electrons originating from the electrode x{sub 0}. Methods: Two methods for deriving the RAKR from the measured ionization charges are: (1) to determine the RAKR from the slope of the linear fit to the so-called ’extrapolation curve’, the measured ionization charges Q vs. plate separations x or (2) to differentiate Q(x) and to derive the RAKR by a linear extrapolation towards zero plate separation. For both methods, correcting the measured data for all known influencing effects before the evaluation method is applied is a precondition. However, the discrepancy of their results is larger than the uncertainty given for the determination of the RAKR with both methods. Results: A new approach to derive the RAKR from the measurements is investigated as an alternative. The method was developed from the ground up, based on radiation transport theory. A conversion factor C(x{sub 1}, x{sub 2}) is applied to the difference of charges measured at the two plate separations x{sub 1} and x{sub 2}. This factor is composed of quotients of three air-kerma values calculated for different plate separations in the chamber: the air kerma Ka(0) for plate separation zero, and the mean air kermas at the plate separations x{sub 1} and x{sub 2}, respectively. The RAKR determined with method (1) yields 4.877 µGy/h, and with method (2) 4.596 µGy/h. The application of the alternative approach results in 4.810 µGy/h. Conclusion: The alternative method shall be established in the future.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2024

Method for electrochemical transformation of amorphous material to crystalline material

A method for converting amorphous boron nitride to crystalline boron nitride, the method comprising immersing the amorphous boron nitride into anhydrous molten magnesium chloride maintained within a temperature range of 720° C.-820° C. while the amorphous boron nitride is cathodically polarized at a voltage within a range of −2.2V to −2.8V for a period of time of at least 2 minutes to result in conversion of the amorphous boron nitride to the crystalline form. Also described herein is a method for converting an amorphous carbon material to a crystalline carbon material, the method comprising immersing said amorphous carbon material into anhydrous molten magnesium chloride maintained within a temperature range of 780° C.-820° C. while the amorphous carbon material is cathodically polarized at a voltage within a range of −2.2V to −2.8V for a period of time of at least 2 minutes to result in conversion of the amorphous carbon material to the crystalline form.

Bagri, Prashant↗
DOE OSTI2019

Catalytic conversion of bio-mass derivable aliphatic alcohols to valuable alkenes or oxygenates

Disclosed is a method for producing, among others, alkenes and/or saturated or unsaturated oxygenates and, which include at least one of an aldehyde and an acid, comprising subjecting the corresponding C3 to C5 aliphatic alcohols that are derivable from biomass, to a vapor phase process over the catalytic system in the presence of a gas mixture of oxygen, air or nitrogen and/or other suitable diluting gas. The catalyst system comprises multi-catalytic zones, in each of which the composition of the co-feed and other reaction parameter can be independently controlled.

Lin, Manhua↗
DOE OSTI2019

Zemach Moments and Radii of 2,3 H and 3,4 He

We present benchmark calculations of Zemach moments and radii of 2,3 H and 3,4 He using various few-body methods. Zemach moments are required to interpret muonic atom data measured by the CREMA collaboration at the Paul Scherrer Institute. Conversely, radii extracted from spectroscopic measurements can be compared with ab initio computations, posing stringent constraints on the nuclear model. For a given few-body method, different numerical procedures can be applied to compute these quantities. A detailed analysis of the numerical uncertainties entering the total theoretical error is presented. Uncertainties from the few-body method and the calculational procedure are found to be smaller than the dependencies on the dynamical modeling and the single nucleon inputs, which are found to be ≲2%. Furthermore when relativistic corrections and two-body currents are accounted for, the calculated moments and radii are in very good agreement with the available experimental data.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗