Search NASA⌕ Search

SEARCH · Search NASA

Results for “conversion methods”

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.

At least 847 records · Page 47
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Environmentally Benign and Scalable Preparation of Diethyl Furoxan-3,4-dicarboxylate Using Silver Carbonate as a Nitrile Oxide Generator

Diethyl furoxan-3,4-dicarboxylate (1) is a starting material for many heterocyclic compounds containing furoxan and furazan rings. Usually, furoxan 1 was prepared via a dimerization of corresponding nitrile oxide generated either by treatment of ethyl 2-chloro-2-(hydroxyimino)-acetate (2) with triethylamine or by nitration or conversion of α-activated ethyl acetate with acetyl nitrate in acetic acid or other catalytic reagents. Both methods are suitable for small-scale but suffered from various drawbacks for large-scale preparation. Years ago, a general method for the preparation of furoxan from corresponding hydroximidoyl chloride (R–CCl=NOH) with silver carbonate (Ag 2 CO 3 ) was developed in our group. Now this method is extended to prepare 1 from 2. The synthesis involves the treatment of 2 with Ag 2 CO 3 in THF at room temperature, with a 3–4 h reaction time, with a yield of 80–90%. Using this method, a one pound batch of the material has been prepared at the lab-scale, but the preparation should be easily scaled to the multikilogram synthesis. This is an environmentally benign process since the preparation generates little hazardous wastes due to the possible recycling of the solvent, THF, and the byproduct, silver chloride.

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

Effect of in Vivo Deuteration on Structure of Switchgrass Lignin

Biomass deuteration is an effective engineering method that can be used to provide key insights into understanding of biomass recalcitrance and the complex biomass conversion process. In this study, production of deuterated switchgrass was accomplished by growing the plants in 50% D 2 O under hydroponic conditions in a perfusion chamber. Cellulolytic enzyme lignin was isolated from deuterated switchgrass, characterized by Fourier transform infrared (FTIR), gel permeation chromatography (GPC), and nuclear magnetic resonance (NMR) and compared with its protiated control sample to determine the effect of in vivo deuteration on the chemical structure of lignin. FTIR results showed that D 2 O can be taken up by the roots and transported to the leaves, and deuterium was subsequently incorporated into hydroxyl and alkyl groups in the plant and its lignin through photosynthesis. According to GPC results, deuterated lignin had slightly higher molecular weight, presumably due to isotope effects. 31 P and heteronuclear single quantum coherence (HSQC) NMR results revealed that lignin in the deuterated biomass preserved its native physicochemical characteristics. Finally, the conserved characteristics of the deuterated lignin show its great potential applications for structural and dynamic studies of lignocellulose by techniques such as neutron scattering.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Optimisation of GaN LEDs and the reduction of efficiency droop using active machine learning

A fundamental challenge in the design of LEDs is to maximise electro-luminescence efficiency at high current densities. We simulate GaN-based LED structures that delay the onset of efficiency droop by spreading carrier concentrations evenly across the active region. Statistical analysis and machine learning effectively guide the selection of the next LED structure to be examined based upon its expected efficiency as well as model uncertainty. This active learning strategy rapidly constructs a model that predicts Poisson-Schrödinger simulations of devices, and that simultaneously produces structures with higher simulated efficiencies.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2015

Enhanced crystalline morphology of a ladder-type polymer bulk-heterojunction device by blade-coating

A blade-coating process was employed to fabricate bulk-heterojunction (BHJ) polymer solar cells based on a ladder-type polymer (PIDT-PhanQ) with low crystallinity. Compared to the devices processed by a conventional spin-coating method, an intriguing morphology with enhanced phase-separation and increased crystallinity was achieved. As a result, power conversion efficiency up to 7.25% could be achieved from the blade-coated PIDT-PhanQ:PC 71 BM BHJ film, surpassing the original value obtained by spin-coating (6.29%). In this work, this improved photovoltaic performance is attributed to the improved charge carrier mobilities, which correlates well with the increased crystallinity and the organized network of the donor–acceptor phases that produce efficient charge-transporting pathways.

36 MATERIALS SCIENCE↗
DOE OSTI2023

High-performance Ruddlesden–Popper perovskite oxide with in situ exsolved nanoparticles for direct CO 2 electrolysis

Carbon dioxide (CO 2 ) is one of the principal greenhouse gases accountable for global warming and extreme climate changes. Electrochemically converting CO 2 into carbon monoxide (CO) is a promising approach for CO 2 utilization in achieving industrial decarbonization. High-temperature CO 2 electrolysis via solid oxide electrolysis cells (SOECs) has great potential, including high-energy efficiency, fast electrode kinetics, and competitive cost; however, this technology still has challenges associated with developing highly active, robust CO 2 electrodes for SOECs. We report novel Ruddlesden–Popper structured Pr 1.2 Sr 0.8 Mn 0.4 Fe 0.6 O 4–δ (RP-PSMF) with in situ exsolved Fe nanoparticles as the CO 2 electrode in SOECs for direct CO 2 conversion to CO. The mechanism of CO 2 electrolysis is studied by using the distribution of relaxation times method from electrochemical impedance spectroscopy. La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3–δ (LSGM)-electrolyte supported SOECs with the RP-PSMF cathode have achieved exceptionally high current densities of 2.90, 1.61, 0.91, and 0.48 A·cm –2 at an applied voltage of 1.5 V at 800, 750, 700, and 650 °C, respectively. Moreover, SOECs with the RP-PSMF cathode have exhibited a stable electrolysis performance for 100 h under a current cycling operation. Here, these results suggest that RP-PSMF with exsolved Fe nanoparticles is a highly promising cathode for high-temperature direct CO 2 electrolysis cells.

03 NATURAL GAS↗
DOE OSTI2025

A new quinoline-based cobalt( II ) catalyst capable of bifunctional water splitting

We report on a new water-soluble cobalt( II ) complex capable of water splitting bifunctionality, i.e., water reduction and water oxidation. The species [Co II (L Qpy )H 2 O]ClO 4 (1), where L Qpy is the deprotonated form of the new tripodal ligand N 1 ,N 1 -bis(pyridin-2-ylmethyl)-N 2 -(quinolin-8-yl)benzene-1,2-diamine, HL Qpy , was developed aiming to replace an oxidation prone methylene group by a sturdy and redox stable quinoline. The molecular and electronic structures of 1 were evaluated by multiple spectroscopic, spectrometric, electrochemical and computational methods, and detailed pre- and post-catalytic studies were conducted to ascertain the molecular nature of the conversions. Complex 1 performs water reduction at a low onset overpotential (η) of 0.65 V at pH 7, reaching TON 3h 2900 (TOF 970 h −1 ) and TON 18h 12 100 (TOF 672 h −1 ) with up to 98% faradaic efficiency (FE). Species 1 also promotes water oxidation at η = 0.34 V under pH 8, achieving TON 3h 193 (TOF 64 h −1 ) at 84% FE. Experimental and DFT results enabled us to propose reaction intermediates and mechanisms.

Lucecki, Carlos A. [Wayne State University, Detroi↗
DOE OSTI2016

“W-X-M” transformations in isomerization of B{sub 39}{sup −} borospherenes

The Stone-Wales transformation plays an important role in the isomerization of fullerenes and graphenic systems. The continuous conversions between neighboring six- and seven-membered rings in the borospherene (all-boron fullerene) B{sub 40} had been discovered (Martínez-Guajardo et al. Sci. Rep. 5, 11287 (2015)). In the first axially chiral borospherenes C{sub 3} B{sub 39}{sup −} and C{sub 2} B{sub 39}{sup −}, we identify three active boron atoms which are located at the center of three alternative sites involving five boron atoms denoted as “W”, “X”, and “M”, respectively. The concerted movements of these active boron atoms and their close neighbors between neighboring six- and seven-membered rings define the “W-X-M” transformation of borospherenes. Extensive first-principles molecular dynamics simulations and quadratic synchronous transit transition-state searches indicate that, via three transition states (TS1, TS2, and TS3) and two intermediate species (M1 and M2), the three-step “W-X-M” transformations convert the C{sub 3} B{sub 39}{sup −} global minimum into its C{sub 2} isomer at room temperature (300 K) and vice versa. The maximum barriers are only 3.89 kcal/mol from C{sub 3} to C{sub 2} B{sub 39}{sup −} and 2.1 kcal/mol from C{sub 2} to C{sub 3} B{sub 39}{sup −}, rendering dynamic fluxionalities to these borospherenes. Therefore, the “W-X-M” transformation plays an important role in the borospherenes and borospherene-based nanostructures.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2019

Wafer-scale on-chip synthesis and field emission properties of vertically aligned boron nitride based nanofiber arrays

One dimensional boron nitride (BN) nanomaterials with a high aspect ratio are of great interest due to their unique properties and potential applications. However, BN nanomaterials are generally difficult to synthesize. Here, we describe the creation of arrays of vertically aligned pure BN nanofibers and BN coated carbon nanofibers, fabricated on-chip via a straightforward template-assisted chemical conversion reaction. The template, a glassy carbon nanofiber array, is produced by plasma processing of conventional photoresists. The method is highly controllable, patternable, and scalable, and the final arrays can be fabricated over large areas with a controlled fiber length. We characterize the electron field emission properties of the BN-coated carbon nanofiber array and find a large field enhancement factor, low turn-on voltage, and good stability. The outstanding field emission performance results from the small tip size and high aspect ratio of the nanofiber as well as the high chemical stability and high thermal conductivity of the BN coating.

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

Improved receiver noise calibration for ADMX axion search: 4.54 to 5.41 μeV

Axions are a well-motivated candidate for dark matter. The preeminent method to search for axion dark matter is known as the axion haloscope, which makes use of the conversion of axions to photons in a large magnetic field. Because of the weak coupling of axions to photons, however, the expected signal strength is exceptionally small. To increase signal strength, many haloscopes make use of resonant enhancement and high gain amplifiers, while also taking measures to keep receiver noise as low as possible such as the use of dilution refrigerators and ultra-low-noise electronics. In this paper, we derive the theoretical noise model based on the sources of noise found within a typical axion haloscope receiver chain, using the Axion Dark Matter eXperiment (ADMX) as a case study. We present examples of different noise calibration measurements at 1280 MHz taken during ADMX’s most recent data-taking run. These new results shed light on a previously unidentified interaction between the cavity and Josephson Parametric Amplifier as well as provide a better understanding of the systematic uncertainty on the system noise temperature used in the axion search analysis for this data-taking run. Finally, the consistency between the measurements and the detailed model provide suggestions for future improvements within ADMX and other axion haloscopes to reach a lower noise temperature.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Narrow-Bandgap Interband Cascade Thermophotovoltaic Cells

In this paper, we report on the characterization of narrow-bandgap (E g ≈ 0.4 eV, at 300 K) interband cascade thermophotovoltaic (TPV) devices with InAs/GaSb/AlSb type-II superlattice absorbers. Two device structures with different numbers of stages (two and three) were designed and grown to study the influence of the number of stages and absorber thicknesses on the device performance at high temperatures (300-340 K). Maximum power efficiencies of 9.6% and 6.5% with open-circuit voltages of 800 and 530 mV were achieved in the three- and two-stage devices at 300 K, respectively. These results validate the benefits of a multiple-stage architecture with thin individual absorbers for efficient conversion of infrared radiation into electricity from low-temperature heat sources. Additionally, we developed an effective characterization method, based on an adapted version of Suns-V oc technique, to extract the device series and shunt resistance in these TPV cells.

14 SOLAR ENERGY↗
DOE OSTI2015

SU-F-BRA-08: An Investigation of Well-Chamber Responses for An Electronic Brachytherapy Source

Purpose: The aim of this study was to investigate the variation of well-type ionization chamber response between a Xoft Axxent™ electronic brachytherapy (EBT) source and a GE Oncoseed™ 6711 I-125 seed. Methods: A new EBT air-kerma standard has recently been introduced by the National Institute of Standards and Technology (NIST). Historically, the Axxent source strength has been based on a well chamber calibration from an I-125 brachytherapy source due to the lack of a primary standard. Xoft utilizes a calibration procedure that employs a GE 6711 seed calibration as a surrogate standard to represent the air-kerma strength of an Axxent source. This method is based on the premise that the energies of the two sources are similar and thus, a conversion factor would be a suitable interim solution until a NIST standard was established. For this investigation, a number of well chambers of the same model type and three different EBT sources were used to determine NIST-traceable calibration coefficients for both the GE 6711 seed and the Axxent source. The ratio of the two coefficients was analyzed for consistency and also to identify any possible correlations with chamber vintage or the sources themselves. Results: For all well chambers studied, the relative standard deviation of the ratio of calibration coefficients between the two standards is less than 1%. No specific trends were found with the well chamber vintage or between the three different EBT sources used. Conclusion: The variation of well chamber calibration coefficients between a Xoft Axxent™ EBT source versus a GE 6711 Oncoseed™ are consistent across well chamber vintage and between sources. The results of this investigation confirm the underlying assumptions and stability of the surrogate standard currently in use by Xoft, and establishes a migration path for future implementation of the new NIST air kerma standard. This research is supported in part by Xoft, a subsidiary of iCAD.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2024

Measurement of the electric potential and the magnetic field in the shifted analysing plane of the KATRIN experiment

The projected sensitivity of the effective electron neutrino-mass measurement with the KATRIN experiment is below 0.3 eV (90 % CL) after 5 years of data acquisition. The sensitivity is affected by the increased rate of the background electrons from KATRIN’s main spectrometer. A special shifted-analysing-plane (SAP) configuration was developed to reduce this background by a factor of two. The complex layout of electromagnetic fields in the SAP configuration requires a robust method of estimating these fields. We present in this paper a dedicated calibration measurement of the fields using conversion electrons of gaseous 83m Kr, which enables the neutrino-mass measurements in the SAP configuration.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Physico-chemical properties of lignin fractions from acid pretreated corn stover and their effects on enzymatic hydrolysis of microcrystalline cellulose

Lignin has been shown to be a recalcitrance factor in many biomass conversion studies. To better understand the effects of lignin on cellulose conversion, different lignin fractions were extracted from the same dilute acid pretreated corn stover by three sequential isolation methods, namely ethanol extraction, dioxane extraction, and enzyme purification. The physicochemical properties of each lignin fraction including molecular weight distribution, surface area, surface charge, and other structural features varied, depending on the isolation methods. All three lignin fractions had negative surface charges, and ethanol-extracted lignin carried the highest surface charges, followed by dioxane-extracted lignin and cellulase-purified residual lignin. These physicochemical properties of lignin fractions also resulted in different extent of inhibitory effects on enzymatic hydrolysis of microcrystalline cellulose (MCC). Dioxane-extracted lignin exhibited the highest inhibitory effect on glucose release from MCC, followed by the cellulase-purified residual lignin fraction and ethanol-extracted lignin. Furthermore, lignin fractions with higher contents of syringyl (S) substructure and β-O-4 aryl ether interunit linkages showed a stronger negative effect on cellulase hydrolysis of MCC.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Final Report: Transforming Organic Photovoltaics into a Fully Practical Energy Solution

The main purpose of this project is to advance the organic photovoltaic cell technology by addressing the three pillars: (I) efficiency, (II) reliability, and (III) low cost and scalability. This project uses several proprietary technologies, such as multi-junction planar mixed solar cells, exciton blocking layers, organic vapor phase deposition (OVPD), liquid and vacuum-phase deposition processes, developed at the University of Michigan. The methods used are based primarily (although not exclusively) on small molecular weight organic materials used in high power conversion efficiency (PCE) single- and multi-junction cells. At the same time, we explore the operational lifetime, and fundamental failure modes for both discrete and multijunction cells employing our most efficient materials sets (as already developed, or to be developed under separate funding). Large test modules consisting of up to (10 cm)2 arrays of 1 cm2 devices will be made using scalable growth technologies including organic vapor phase deposition (OVPD), liquid and vacuum-phase deposition processes developed in our laboratory. All deposition techniques used have the ability to scale to very large substrates, including having compatibility with roll-to-roll deposition.

14 SOLAR ENERGY↗
DOE OSTI2020

Current measurements in the intermittent-contact mode of atomic force microscopy using the Fourier method: a feasibility analysis

Atomic force microscopy (AFM) is an important tool for measuring a variety of nanoscale surface properties, such as topography, viscoelasticity, electrical potential and conductivity. Some of these properties are measured using contact methods (static contact or intermittent contact), while others are measured using noncontact methods. Some properties can be measured using different approaches. Conductivity, in particular, is mapped using the contact-mode method. However, this modality can be destructive to delicate samples, since it involves continuously dragging the cantilever tip on the surface during the raster scan, while a constant tip–sample force is applied. In this paper we discuss a possible approach to develop an intermittent-contact conductive AFM mode based on Fourier analysis, whereby the measured current response consists of higher harmonics of the cantilever oscillation frequency. Such an approach may enable the characterization of soft samples with less damage than contact-mode imaging. To explore its feasibility, we derive the analytical form of the tip–sample current that would be obtained for attractive (noncontact) and repulsive (intermittent-contact) dynamic AFM characterization, and compare it with results obtained from numerical simulations. Although significant instrumentation challenges are anticipated, the modelling results are promising and suggest that Fourier-based higher-harmonics current measurement may enable the development of a reliable intermittent-contact conductive AFM method.

14 SOLAR ENERGY↗
DOE OSTI2016

GaAs thin films and methods of making and using the same

Disclosed herein are embodiments of methods for making GaAs thin films, such as photovoltaic GaAs thin films. The methods disclosed herein utilize sources, precursors, and reagents that do not produce (or require) toxic gas and that are readily available and relatively low in cost. In some embodiments, the methods are readily scalable for industrial applications and can provide GaAs thin films having properties that are at least comparable to or potentially superior to GaAs films obtained from conventional methods.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2015

BASTet (Berkeley Analysis and Storage Toolkit)

BASTet is an advanced software library written in Python. BASTet serves as the analysis and storage library for the OpenMSI project. BASTet is an integrate framework for: i) storage of spectral imaging data, ii) storage of derived analysis data, iii) provenance of analyses, iv) integration and execution of analyses via complex workflows. BASTet implements the API for the HDF5 storage format used by OpenMSI. Analyses that are developed using BASTet benefit from direct integration with storage format, automatic tracking of provenance, and direct integration with command-line and workflow execution tools. BASTet also defines interfaces to enable developers to directly integrate their analysis with OpenMSI's web-based viewing infrastruture without having to know OpenMSI. BASTet also provides numerous helper classes and tools to assist with the conversion of data files, ease parallel implementation of analysis algorithms, ease interaction with web-based functions, description methods for data reduction. BASTet also includes detailed developer documentation, user tutorials, iPython notebooks, and other supporting documents.

Bowen, Benjamin↗
DOE OSTI2018

Biologically Inspired Ammonia Production with Immobilized Nitrogenase Final Report

Ammonia is a critical component of the US economy as US agricultural exports exceeded $100BB in 2015 and depend heavily on ammonia fertilizers. Ammonia production consumes 1% of the world’s total energy supply and millions of tons are imported each year. An innovative bioelectrocatalyzed process is being developed using immobilized mutated nitrogenase enzymes to directly convert atmospheric nitrogen to ammonia at standard conditions, 25° C and 1 atm, and without the need for natural gas. This technology utilizes an enhanced enzyme and advanced enzyme immobilization method for increased production efficiency. The Phase I project developed a new enzyme and polymer support structure which enables direct conversion of nitrogen to ammonia under mild conditions without the need for added chemicals; only electricity and water are required. The system exhibited significantly higher efficiency than competing technologies. The Phase II project will develop a commercial process for the enzyme/polymer system. This will include scaling up production of the enzyme and determining process conditions for maximum productivity. This technology is intended for the commercial fertilizer industry, which currently uses large, expensive plants for centralized production, consuming vast amounts of natural gas and generating significant CO 2 pollution. This technology could also be used to generate alternative ammonia-based fuel and ammonia-based commodity chemicals. The Federal Government would benefit from this technology by reducing dependence on foreign imports, and increasing domestic production of a commodity chemical. Ammonia is used as key component in explosives and propellants and is essential for national security. Distributed production will lower the vulnerability of this resource. The key benefit for the customer is lower capital and operating cost. Building new ammonia production plants cost >$2BB with considerable infrastructure costs to ship the ammonia. The primary method of transportation is pipe to truck distribution, although some is still carried via railway. The feature that set our technology apart from the current Haber-Bosch process is the ability for low-cost distributed production.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗