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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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Applied Magnetic Field Increases Magnetic Anisotropy in HDDR-Processed Nd-Fe-B Alloy

We investigate the effect of an applied magnetic field on the entire HDDR process using a customized reactor vessel and a warm-bore superconducting magnet. We analyzed the resulting properties produced at both a 0 applied field and a 2 Tesla applied field. We show that the application of a magnetic field throughout the HDDR process results in powders that exhibit a greater level of anisotropy compared to their ambient field counterparts.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Handling and Properties of Methanol as a Marine Fuel

Given the increasing concern around greenhouse gas emissions and the decline in the availability of fossil fuels, there is increasing global demand to develop alternate fuels for maritime transportation that are sustainable and which have lower greenhouse gas emissions. Methanol is one such alternative fuel that has garnered considerable attention given its potential to be produced by more sustainable processes and its more favorable greenhouse gas emission profile in comparison with current fossil fuels. Understanding the physical and chemical properties of methanol under a range of conditions is essential for its development as a marine fuel. In this study, we seek to define physical and chemical properties of different methanol samples to simulate real-world storage conditions as these data are lacking in the literature. Several methanol samples were evaluated: nearly pure methanol; International Organization for Standardization (ISO) marine methanol (MM) grades A, B, and C; and methanol plus higher alcohols. We first evaluated all methanol samples for impurities, acetic acid content, density, and distillation range. We then characterized the effects of water absorption and found that methanol can easily absorb unacceptable water content from humid air within hours, necessitating storage conditions that prevent this process. In eight-week aging experiments at 20 °C and 40 °C in ambient air, we did not observe significant oxidation for any of the methanol samples; however, we did observe increases in acid number. We assessed the impact of contamination of methanol with water, marine gas oil (MGO), and an MGO–biodiesel mixture on density, viscosity, distillation range, and lubricity. Finally, we show that MGO contamination of methanol results in a slight increase in sooting tendency. In aggregate, our results provide an in-depth analysis of physical and chemical properties of methanol as well as the impacts of storage conditions and impurities on the properties of fuel methanol.

09 BIOMASS FUELS↗
DOE OSTI2021

Field Experiments and Model Validation: The EGS Collab Project

Implementing enhanced geothermal systems (EGS) will require improvements in understanding stimulation of crystalline rock to create appropriate flow pathways, and the ability to effectively simulate both the stimulation and the flow and transport processes in the resulting fracture network. The US Department of Energy (DOE) is addressing these and other challenges at multiple scales. The EGS Collab project, addressed here, is performing tests and modeling at the 10 m scale. The FORGE project is performing tests at the full reservoir scale. The EGS Collab team created an underground testbed at the Sanford Underground Research Facility (SURF) in Lead, South Dakota, at a depth of approximately 1.5 km to examine hydraulic fracturing (Experiment 1). We are currently building a second testbed at SURF at a depth of about 1.25 km aimed at investigating shear stimulation (Experiment 2). In Experiment 1, we drilled eight boreholes in a well-characterized phyllite and installed geophysical sensors in six of them to create a well-instrumented testbed to allow careful monitoring of stimulation events and flow tests. Numerical simulation was used to answer key experimental design questions, to forecast fracture propagation trajectories and extents, and to analyze and evaluate results both in near-real-time and in detailed process studies. Stimulations performed in this testbed allowed quantification of processes occurring during stimulation and the examination of dynamic flow occurrences. Long-term ambient temperature and chilled water flow tests were performed in addition to many tracer tests to examine system behavior. Our second testbed, targeted at shear stimulation, is currently being built at the SURF Facility at a depth of about 1.25 km in amphibolite under a different set of stress and fracture conditions than Experiment 1.

artificial intelligence↗
DOE OSTI2022

Latent-Space Dynamics for Prediction and Fault Detection in Geothermal Power Plant Operations

This paper presents a latent-space dynamic neural network (LSDNN) model for the multi-step-ahead prediction and fault detection of a geothermal power plant’s operation. The model was trained to learn the dynamics of the power generation process from multivariate time-series data and the effects of exogenous variables, such as control adjustment and ambient temperature. In the LSDNN model, an encoder–decoder architecture was designed to capture cross-correlation among different measured variables. In addition, a latent space dynamic structure was proposed to propagate the dynamics in the latent space to enable prediction. The prediction power of the LSDNN was utilized for monitoring a geothermal power plant and detecting abnormal events. The model was integrated with principal component analysis (PCA)-based process monitoring techniques to develop a fault-detection procedure. The performance of the proposed LSDNN model and fault detection approach was demonstrated using field data collected from a geothermal power plant.

15 GEOTHERMAL ENERGY↗
DOE OSTI2020

Identifying a regional aerosol baseline in the eastern North Atlantic using collocated measurements and a mathematical algorithm to mask high-submicron-number-concentration aerosol events

Abstract. High-time-resolution measurements of in situ aerosol and cloud properties provide the ability to study regional atmospheric processes that occur on timescales of minutes to hours. However, one limitation to this approach is that continuous measurements often include periods when the data collected are not representative of the regional aerosol. Even at remote locations, submicron aerosols are pervasive in the ambient atmosphere with many sources. Therefore, periods dominated by local aerosol should be identified before conducting subsequent analyses to understand aerosol regional processes and aerosol–cloud interactions. Here, we present a novel method to validate the identification of regional baseline aerosol data by applying a mathematical algorithm to the data collected at the U.S. Department of Energy's (DOE) Atmospheric Radiation Measurement (ARM) user facility in the eastern North Atlantic (ENA). The ENA central facility (C1) includes an aerosol observing system (AOS) for the measurement of aerosol physical, optical, and chemical properties at time resolutions from seconds to minutes. A second temporary supplementary facility (S1), located ∼0.75 km from C1, was deployed for ∼1 year during the Aerosol and Cloud Experiments (ACE-ENA) campaign in 2017. First, we investigate the local aerosol at both locations. We associate periods of high submicron number concentration (Ntot) in the fine-mode condensation particle counter (CPC) and size distributions from the Ultra-High Sensitivity Aerosol Spectrometer (UHSAS) as a function of wind direction using a meteorology sensor with local sources. Elevated concentrations of Aitken-mode (< 100 nm diameter) particles were observed in correspondence with the wind directions associated with airport operations. At ENA, the Graciosa Airport and its associated activities were found to be the main sources of high-concentration aerosol events at ENA, causing peaks in 1 min Ntot that exceeded 8000 and 10 000 cm−3 at C1, in summer and winter, respectively, and 5000 cm−3 at S1 in summer. Periods with high Ntot not associated with these wind directions were also observed. As a result, the diverse local sources at ENA yielded a poor relationship between Ntot measurements collected at C1 and S1 (R2=0.03 with a slope =0.05±0.001). As a first approach to mask these events, the time periods when the wind direction was associated with the airport operations (west to northwest and southeast to south at C1 and east to south at S1) were applied. The meteorological masks removed 38.9 % of the data at C1 and 43.4 % at S1, and they did not significantly improve the relationship between the two sites (R2=0.18 with a slope =0.06±0.001). Due to the complexity of high-Ntot events observed at ENA, we develop and validate a mathematical ENA Aerosol Mask (ENA-AM) to identify high-Ntot events using 1 min resolution data from the AOS CPC at C1 and S1. After its parameterization and application, ENA-AM generated a high correlation between Ntot in the summer at C1 and S1 (R2=0.87 with a slope =0.84±0.001). We identified the regional baseline at ENA to be 428±228 cm−3 in the summer and 346±223 cm−3 in the winter. Lastly, we compared masked measurements from the AOS with the ARM Aerial Facility (AAF) during flights over C1 in the summer to understand submicron aerosol vertical mixing over C1. The high correlation (R2=0.71 with a slope of 1.04±0.01) observed between C1 and the AAF Ntot collected within an area of 10 km surrounding ENA and at altitudes < 500 m indicated that the submicron aerosol at ENA was well mixed within the first 500 m of the marine boundary layer during the month of July during ACE-ENA. Our novel method for determining a regional aerosol baseline at ENA can be applied to other time periods and at other locations with validation by a secondary site or additional collocated measurements.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

The Edge of Exploration: An Edge Storage and Computing Framework for Ambient Noise Seismic Interferometry Using Internet of Things Based Sensor Networks

Recent technological advances have reduced the complexity and cost of developing sensor networks for remote environmental monitoring. However, the challenges of acquiring, transmitting, storing, and processing remote environmental data remain significant. The transmission of large volumes of sensor data to a centralized location (i.e., the cloud) burdens network resources, introduces latency and jitter, and can ultimately impact user experience. Edge computing has emerged as a paradigm in which substantial storage and computing resources are located at the “edge” of the network. In this paper, we present an edge storage and computing framework leveraging commercially available components organized in a tiered architecture and arranged in a hub-and-spoke topology. The framework includes a popular distributed database to support the acquisition, transmission, storage, and processing of Internet-of-Things-based sensor network data in a field setting. We present details regarding the architecture, distributed database, embedded systems, and topology used to implement an edge-based solution. Lastly, a real-world case study (i.e., seismic) is presented that leverages the edge storage and computing framework to acquire, transmit, store, and process millions of samples of data per hour.

58 GEOSCIENCES↗
DOE OSTI2025

Arsenic activation and compensation in single crystal CdTe bilayers

In state-of-the art polycrystalline CdTe photovoltaics, group-V dopant activation is about 2%. Low activation can create electronic defects and lead to recombination and band tail losses. To develop methods to overcome this limitation, dopant activation was systematically investigated using molecular beam epitaxy (MBE) grown single crystal bilayers of As-doped CdTe on undoped CdTe. Results suggest multiple paths for improved As-activation in polycrystalline CdTe-based devices. It was found that the carrier concentration in this MBE material saturated at ∼3 × 1016 cm−3, with high levels (>50%) of As-activation possible. High activation could be achieved with a post-growth activation temperature of ∼450 °C, when the initial doping level was below the saturation level. However, at typical polycrystalline As incorporation levels (>5 × 1016 cm−3), the excess As is inactive or compensating, requiring elevated temperatures (500–600 °C) to achieve high activation. Oxygen in the annealing ambient was detrimental, while the effect of CdCl2 in the ambient is more case-dependent. A 575 °C activation anneal was combined with a 450 °C CdCl2 treatment to better understand the implications for polycrystalline CdTe. Interestingly, on highly doped samples, processes ending with a high temperature step displayed high activation, while those ending at 450 °C significantly reduced the carrier concentration (with or without CdCl2 in the ambient). Low activation can be restored with another high temperature anneal, allowing reproducible toggling between high and low activation based on the final temperature. Photoluminescence revealed the presence of donor–acceptor pairs in the low activation state that appear to be associated with a compensating defect.

14 SOLAR ENERGY↗
DOE OSTI2020

Electrocatalytic Valorization into H2 and Hydrocarbons of an Aqueous Stream Derived from Hydrothermal Liquefaction

Electrocatalytic oxidation is an attractive process for valorizing the carbon and removal of nitrogen present in the aqueous waste streams at ambient conditions. Here, we evaluated the electrocatalytic oxidation as a function of applied potential over a commercial Pt electrode of aqueous waste stream generated via hydrothermal liquefaction. We validated the conversion of quantifiable carbon (e.g., carboxylic acids, alpha hydroxyacids, alcohols, ketones, amides) and unquantifiable carbon as well as nitrogen removal. The unquantifiable carbon was valorized to quantifiable short chain organic molecules (e.g., acetic). Model studies showed that carboxylic acids, alcohol and ketones converted following (non-) Kolbe chemistry. Amides and alpha hydroxyacids formed carboxylic acids that subsequently converted via (non-) Kolbe chemistry. Ammonia was oxidized into N2. The reaction rate varied for each molecule family with carboxylic acids and ammonia having the highest reaction rates. The main reaction products from the electrocatalytic oxidation at the anode were volatile, short chain hydrocarbons (i.e., olefins, paraffins) and CO generated via Kolbe chemistry, while H2 was generated at the cathode. The parallel denitrification, valorization of carbon, and H2 generation of the aqueous waste can replace and simplify the current unit operations used in a commercial hydrothermal liquefaction process. The high operation potential required to drive the electrocatalytic reaction is responsible for high operation costs; however, they can be either partially subsidized with sale of excess H2 at the current DOE goal of $2/kg H2. Thus, the present work shows how electrocatalytic oxidation can be used to valorize aqueous waste streams into volatile hydrocarbons and H2.

Electrocatalytic oxidation, Aqueous waste valoriza↗
DOE OSTI2025

Autonomous Aerosol and Plasma Co‐Jet Printing of Metallic Devices at Ambient Temperature

Abstract Additive manufacturing of metallic materials holds the potential to revolutionize the fabrication of functional devices unattainable via traditional methods. Despite recent advancements, printing metallic materials typically requires thermal processing at elevated temperatures to form dense structures with desired properties, which presents a major challenge for direct printing and integration with temperature‐sensitive materials. Herein, a unique co‐jet printing (CJP) method is reported integrating an aerosol jet and a non‐thermal, atmospheric pressure plasma jet to enable concurrent aerosol deposition of metal nanoparticle inks and in situ sintering at ambient temperature. A machine learning algorithm is integrated with the CJP to perform real‐time defect detection and autonomous correction, enhancing the yield of printed films with high electrical conductivity from 44% to 94%. Concurrent printing and sintering eliminate the need for post‐printing processing, reducing the overall manufacturing time by multiple folds depending on product size. CJP enables direct printing of functional devices on a variety of temperature‐sensitive materials including biological materials. Direct printing of hydration sensors on living plant leaves is demonstrated for long‐duration monitoring of hydration level in the plant. The versatile CJP method opens tremendous opportunities to harmoniously integrate abiotic and biotic materials for emerging applications in wearable/implantable devices and biohybrid systems.

Du, Yipu [Department of Aerospace and Mechanical E↗
DOE OSTI2025

Numerical Investigation of Ammonia/n-Heptane Dual-Fuel Spray Flames Using Large Eddy Simulations

Diesel engines are extensively used in heavy-duty transportation, power generation, and marine vehicles due to their superior thermal efficiency and extended high-load operability compared to spark ignition (SI) engines. However, combustion in diesel engines is generally characterized by locally rich fuel–air mixtures and high combustion temperatures, causing significant amounts of soot and NO x emissions from these engines. Utilizing carbon-free alternative fuels and enhancing fuel efficiency represent promising strategies to mitigate greenhouse gas (GHG) and other emissions in the heavy-duty transportation sector. In this context, ammonia (NH 3 ), as a hydrogen carrier, has received significant attention as a viable substitute for hydrocarbon fuels due to its carbon-free composition, relatively high energy density, and well-established infrastructure. Many previous studies have considered combustion and emission characteristics of ammonia-hydrocarbon fuel blends in engines and simplified flames. But, detailed investigations on the effects of ammonia on the performance of hydrocarbon fuels under engine conditions are lacking. In the present study, we perform large eddy simulations (LES) of the ignition and flame processes in a constant-volume combustion reactor, where n-heptane is injected in an ammonia/air ambient mixture in a diesel-like environment. A detailed and validated reaction mechanism containing 302 species and 1981 reactions is employed. The Engine Combustion Network Spray H experimental data is used to validate the spray model under both non-reacting and reacting conditions. Dual-fuel combustion is simulated using the well-stirred reactor (WSR) approach. Results are presented for two spray cases: (1) single fuel (SF) with n-heptane injected into a mixture of air and combustion products and (2) dual-fuel (DF) with the injection of n-heptane in a mixture of air, ammonia, and combustion products. It is observed that the presence of ammonia has a significant effect on the ignition and flame development processes. With ammonia addition, both the first- and second-stage ignition delay times increase, but the effect of ammonia on the second-stage ignition is significantly more prominent. In addition, the ignition kernel size and growth rate decrease noticeably. For SF spray, the main ignition is characterized by multiple ignition kernels near the spray tip, whereas for DF spray, a single relatively small ignition kernel forms and grows slowly in the downstream direction. The flame development and the final quasi-steady flame structure are also modified due to ammonia. Here, the outcome of this research would enable a better understanding of ammonia–diesel dual-fuel spray flame behavior and guide the development of associated engine combustion strategies.

ammonia↗
DOE OSTI2025

Efficient Synthetic Natural Gas Production from Direct Air Capture Using Titania-Based Dual Function Materials

Converting atmospheric CO2 into methane offers a compelling pathway to store intermittent renewable electricity and enhance energy security using existing natural gas infrastructure. However, current CO2 utilization approaches remain energy- and capital-intensive, largely due to the need for separate capture, purification, and conversion steps. Integrating CO2 capture with catalytic methanation represents a transformative strategy for process intensification on both the unit operation and molecular levels. We report a series of Ru-Na/TiO2 dual function materials (DFMs) for a reactive carbon capture (RCC) process consisting of simulated direct air capture and subsequent CO2 methanation (DACM). Superior methane desorption purity was observed on TiO2-based DFMs (>94 %) relative to state-of-the-art Al2O3-supported DFMs (77 %). Modifying the process to begin CO2 adsorption immediately following the methanation stage, rather than beginning adsorption near ambient temperature, resulted in >97 % methane desorption purity, suitable for injection into the natural gas pipeline without additional CO2 separation steps.

organic↗
DOE OSTI2024

Understanding Anomalous Gas-Phase Peak Shifts in Dip-and-Pull Ambient Pressure XPS Experiments

Dip-and-pull ambient pressure X-ray photoelectron spectroscopy (AP-XPS) holds promise to uncover elementary processes of (photo)electrochemistry. We show, however, that the sample for such experiments should preferably be nonporous and the potential on the surface homogeneous. We carried out dip-and-pull AP-XPS experiments on a hematite thin film sample under the photoelectrochemical oxygen evolution reaction (OER) and find unexpected O 1s core level shifts. Upon electrochemical biasing under simulated solar light illumination, the gas-phase water peak shifted more than the electrolyte peak. To uncover the origin of the unexpected larger shift of the gas-phase peak, we performed electrostatic simulations using COMSOL, to map the potential field in the relevant volume between the sample and the first aperture of the XPS spectrometer. A number of geometric models were considered. We find that when the potential on the sample surface is inhomogeneous, e.g., with ionically isolated electrolyte patches, the gas-phase peak of the spectrum can shift more than the peak due to the electrolyte film. This suggests that at the measured sample position, the local potential was not as set by the potentiostat. Despite this, we find reversible consumption and replenishment of hydroxide in the spectra, which, due to OH– being the reactant of the OER in alkaline electrolyte, makes sense chemically. We propose that this is linked to OH– diffusion across the measured sample position, driven by the potential dependent consumption and replenishment of OH– at the nearby well-connected surface regions.

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

Synthesis of Nitro Compounds from Nitrogen Dioxide Captured in a Metal-Organic Framework

Increasing levels of air pollution are driving the need for the development of new processes that take “waste-to-chemicals”. Herein, we report the capture and conversion under ambient conditions of a major air pollutant, NO 2 , using a robust metal-organic framework (MOF) material, Zr-bptc (H 4 bptc = 3,3',5,5'-biphenyltetracarboxylic acid), comprising {Zr 6 (μ 3 -O) 4 (μ 3 -OH) 4 (COO) 12 } clusters linked by 4-connected bptc 4– ligands in an ftw topology. At 298 K, Zr-bptc shows exceptional stability and adsorption of NO 2 at both low (4.9 mmol g –1 at 10 mbar) and high pressures (13.8 mmol g –1 at 1.0 bar), as measured by isotherm experiments. Dynamic breakthrough experiments have confirmed the selective retention of NO 2 by Zr-bptc at low concentrations under both dry and wet conditions. The immobilized NO 2 can be readily transformed into valuable nitro compounds relevant to construction, agrochemical, and pharmaceutical industries. In situ crystallographic and spectroscopic studies reveal strong binding interactions of NO 2 to the {Zr 6 (μ 3 -O) 4 (μ 3 -OH) 4 (COO) 12 } cluster node. This study paves a circular pathway to enable the integration of nitrogen-based air pollutants into the production of fine chemicals.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Environmental stability impacts the differential sensitivity of marine microbiomes to increases in temperature and acidity

Ambient conditions shape microbiome responses to both short- and long-duration environment changes through processes including physiological acclimation, compositional shifts, and evolution. Here, we predict that microbial communities inhabiting locations with larger diel, episodic, and annual variability in temperature and pH should be less sensitive to shifts in these climate-change factors. To test this hypothesis, we compared responses of surface ocean microbes from more variable (nearshore) and more constant (offshore) sites to short-term factorial warming (+3 °C) and/or acidification (pH –0.3). In all cases, warming alone significantly altered microbial community composition, while acidification had a minor influence. Compared with nearshore microbes, warmed offshore microbiomes exhibited larger changes in community composition, phylotype abundances, respiration rates, and metatranscriptomes, suggesting increased sensitivity of microbes from the less-variable environment. Moreover, while warming increased respiration rates, offshore metatranscriptomes yielded evidence of thermal stress responses in protein synthesis, heat shock proteins, and regulation. Future oceans with warmer waters may enhance overall metabolic and biogeochemical rates, but they will host altered microbial communities, especially in relatively thermally stable regions of the oceans.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Treatment of brackish water reverse osmosis brine using only solar energy

Post-treatment of brine produced by reverse osmosis (RO) is a great challenge as it often requires high energy input and works under extreme operating conditions. In this study, brine from a RO plant in El Paso, TX USA was successfully treated using a pilot-scale nanophotonics enhanced solar membrane distillation (NESMD) system. The novel NESMD reactor has a nanophotonic membrane surface area of 0.2 m 2 and an internal heat recovery system to recover the latent heat released during vapor condensation. By utilizing a sweeping gas operational mode under real solar irradiation (585–827 W m -2 ), the NESMD realized successful desalination of RO brine with the membrane flux reaching 0.45–0.65 kg m -2 h -1 and total dissolved solids (TDS) removal greater than 99.5% without an external heat condenser. The decrease in the feed flow rate to the evaporation channel of the NESMD system led to an increase in the gained output ratio (GOR) from 0.35 to 0.62. We report to the best of our knowledge, this is the largest photothermal reactor utilized for the desalination of real RO brine under practical solar irradiation. Compared with conventional brine treatment processes that require high temperature or pressure, the NESMD desalinates RO brine at near-ambient temperature and pressure with free solar energy, providing a promising approach for water desalination, and RO brine post treatment.

42 ENGINEERING↗
DOE OSTI2023

Topology driven and soft phonon mode enabled Na-ion diffusion in quaternary chalcogenides, Na 3 ZnGaX 4 (X = S, and Se)

The compounds Na 3 ZnGaX 4 (X = S, Se) are potential solid electrolyte materials in sodium-based batteries, which have certain advantages over oxide materials and have shown significant ionic conductivity at ambient temperature. In this paper, we bring out atomic-level features of the diffusion process in these new materials using the microscopic techniques of inelastic neutron scattering (INS), quasielastic neutron scattering (QENS), and ab initio molecular dynamics (AIMD) simulations. The insights obtained from these techniques are unique and not available from other macroscopic experiments. Neutron scattering experiments have been performed at temperatures from 100 to 700 K. The simulations have been carried out up to 900 K. We have calculated the phonon spectra and the space–time correlation functions and found good agreement with the results of the neutron scattering experiments. The simulations enable detailed analysis of the atomic-site dependent dynamical information. We observe low-energy phonon modes of ~6 meV involving the vibrations of certain Na atoms in the lattice. This reveals that the Na at 32g Wyckoff sites (Na2) has sufficiently shallow potential among the two available crystallographic sites. This shallow potential facilitates diffusion. Furthermore, the specific structural topology of the network of interconnected zig-zag chains of the Na2 atomic sites provides the low-barrier energy pathways for diffusion. A small fraction of vacancy defects appears essential for diffusion. We further observe that the Na2 atoms undergo jump-like diffusion to the vacant next or the 2nd next neighbour sites at ~4 Å. While the QENS experiments reveal the jump-like diffusion and its time scale, detailed analysis of the AIMD simulations shows that the jumps appear mostly along zig-zag chains of the Na2 sites in the tetragonal ab-plane, as well as between the chains along the c-axis. In conclusion, the net diffusion is essentially 3-dimensional, with little anisotropy despite the anisotropy of the tetragonal crystal structure.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Polarization Imaging for International Safeguards (FY2019)

A polarization imaging camera, Salsa (Bossa Nova Technologies) was evaluated for use in nuclear safeguards inspection with a focus on swipe sampling. The camera and supporting electronics and software determine the full Stokes parameters for the entire image field. The camera can be used for real-time video or still images. Stokes parameters S0, S1, S2, and S3 can be recorded for each pixel and exported for post processing. This study compared color photography to polarization imaging for powders on many surfaces under ambient lighting. False color images can be created from the Stokes parameters directly from the vendor software to highlight the various polarization states. In most cases, linear polarization showed the greatest effects. The polarization images are easy to collect and very sensitive to surfaces and textures. Fine powders are highlighted in the images, and particle size and refractive index effects were noticed. The images are not affected by ambient lighting (angle, or intensity). Lens choice is key and may require expert knowledge. Very small deposits of 1 µm particles were difficult to image using the standard video lens. General dirt on smooth surfaces and handprints are easily documented as well as powders on textured painted surfaces. Scratches on metal surfaces can be readily separated from other image features. The camera may be useful for tamper indication as surface damage is easy to discern and ambient lighting is not a concern.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2021

Separation of alkane and alkene mixtures by metal–organic frameworks

The separation of alkane/alkene gas mixtures represents an important yet challenging process in the petrochemical industry to produce valuable chemical feedstocks with sufficiently high purity. These molecules have similar physical properties, making their separation difficult and capital-intensive. The current separation and purification technology relies largely on heat-driven distillations with a huge unit composed of hundreds of trays. Adsorptive separation using porous solids is capable of accomplishing the purification under ambient conditions, offering potential energy and environmental benefits. In particular, metal–organic frameworks (MOFs) hold enormous promise for this separation process in light of their highly tunable pore shape, pore size, and pore surface functionality. In this review article, we provide a comprehensive account of metal–organic frameworks that have been investigated for the separation of alkanes and alkenes with a focus on C 2 –C 3 hydrocarbons. Here, the material design rationale, separation mechanisms, and structure–property relations are highlighted. Finally, the existing challenges and possible design strategies for desirable materials are also discussed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗