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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,495 records · Page 83
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Commissioning of a GeoMelt Vitrification Plant at the Central Laboratory on the Sellafield Site - 17561

The National Nuclear Laboratory (NNL) and Kurion Veolia (Kurion) have installed a GeoMelt{sup R} In-Container Vitrification (ICV){sup R} radioactive waste treatment system in the Central Laboratory Active Rig Hall at Sellafield. This installation was completed in 2016. GeoMelt incorporates a range of patented and proprietary vitrification processing technologies that are configured in a variety of ways depending on the project and the waste. GeoMelt transforms hazardous chemical and radioactive wastes into an inert vitreous monolith. Hazardous organics are destroyed by pyrolysis and heavy metals and radionuclides are immobilized within the glass matrix where they are not preferentially leached into the environment. GeoMelt IVC produces a durable wasteform for a large variety of input wastes. The batch nature of the process which involves single-use refractory offers a wide range of process benefits over traditional vitrification technologies including: - a wide range of waste chemistries allowing high waste loadings; - compatibility with heterogeneous wastes including wastes with high metal content; - a technological simple solution without stirrers, bubblers, etc.; - No refractory corrosion concerns or melter drain failure scenarios; - Flexibility in glass chemistry and melter/disposal container configuration allows the wasteform to be specifically tailored to the storage or disposal site requirements. As part of the 2016 system commissioning at NNL's Central Laboratory, three demonstration melts were performed, one funded by Sellafield Ltd. and two by the Nuclear Decommissioning Authority (NDA). The first melt processed inactive soil with an inactive caesium tracer. The second melt processed inactive soil with a Cs-137 tracer. The third melt processed active waste soil from a variety of NDA nuclear licensed sites. The work conducted during commissioning was multi-purpose; it successfully demonstrated the benefits that the GeoMelt technology could bring to the UK NDA estate while performing equipment testing/troubleshooting and operator training. A significant benefit of the GeoMelt ICV technology is volume reduction for wastes which would otherwise experience a volume increase if encapsulated. Another benefit is the ability to treat difficult radioactive waste streams not amenable to encapsulation (e.g., reactive and/or organic wastes) with a very low energy consumption. The purpose of the first commissioning melt, Plant Performance Demonstration (PPD)-1, was to operate the GeoMelt system under typical conditions and to perform a post-melt mass balance of the caesium as a surrogate for Cs-137 in order to access retention of caesium in the final glass product. The melt processed a mixture of inactive soil obtained near the Sellafield site (as analogue for contaminated Sellafield soil), additives, and glass frit. An inactive caesium tracer was added to this melt as Cs{sub 2}CO{sub 3}. The purpose of the second commissioning melt, PPD-2, was to operate the GeoMelt system under typical conditions and to perform a post-melt activity balance using a Cs-137 tracer in order to assess retention of Cs-137 in the final glass product. Materials processed were inactive soil, glass frit, additives, and a radioactive caesium tracer (CsCl). The purpose of the third melt, Experiment-1 (EX-1) was to treat active waste and inactive waste simulant, as a demonstration of simultaneous processing of multiple waste streams. EX-1 consisted of processing active soil, Magnox sludge simulant, inactive soil, additives, and frit. The active soil used for this melt was obtained from the Hunterston A, Bradwell, Capenhurst, and Sellafield nuclear licensed sites. Since most soils are high in silica, the concept for this experiment was to use the active soils to provide glass formers while co-processing Magnox sludge simulant which does not contain glass formers. Beyond demonstration of capability areas of focus of this series of demonstrations included processing efficiency (kWh/kg treated) and caesium retention (%). This paper summarizes operations and results of the three melts. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Design and Construction of the Paddys Run Streambank Stabilization Project at the Fernald Preserve, Harrison, Ohio - 16165

The Fernald Preserve is a former uranium-processing plant that underwent extensive remediation pursuant to CERCLA and is now managed by the US DOE Office of Legacy Management. While remediation of buildings and soil contamination was completed in 2006, aquifer remediation is ongoing. Paddys Run is a second-order stream that runs to the south along the western side of the Fernald Preserve. The Paddys Run watershed encompasses nearly 41 km{sup 2} (16 mi{sup 2}), including most of the Fernald site. Field personnel conducting routine site inspections in March 2014 observed that Paddys Run was migrating east via bank erosion into the 'Pit 3 Swale', an area of known surface-water contamination. The soil there was certified pursuant to site regulatory agreements and meets all final remediation levels. However, weekly surface-water monitoring is conducted from two puddles within the swale area, when water that exceeds the final remediation levels is present. Paddys Run had migrated east approximately 4 m (13 ft) in 2 years and was approximately 29 m (95 ft) from the sample location. This rapid migration threatened existing conditions that allowed for continued monitoring of the swale area and also threatened Paddys Run water quality. Therefore, DOE and regulators determined that the east bank of Paddys Run required stabilization. This was accomplished with a design that included the following components: relocation of approximately 145 m (475 ft) of streambed 9 m (30 ft) west, installation of a rock toe along the east bank, installation of two cross-vane in-stream grade-control structures, stabilization of a portion of the east bank using soil encapsulated lifts, and regrading, seeding, and planting within remaining disturbed areas. In an effort to take advantage of low-flow conditions in Paddys Run, construction was initiated in September 2014. Weather delays and subsurface flow within the Paddys Run streambed resulted in an interim shutdown of the project area in December 2014. Construction activities resumed in April 2015, with completion in November 2015. To date, this stabilization project has been successful. The regraded bank and streambed have remained stable, and no compromise to installed cross-vanes, the rock toe, or the soil encapsulated lifts has been observed. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

In-Situ Gamma-Ray Assay of the 235-F Plutonium Fuel Form Facility at the Savannah River Site - 16293

The Plutonium Fuel Form (PuFF) Facility is located in Building 235-F near the geographic center of the Savannah River Site. Between 1978 and 1984, the facility was used to produce approximately 165 kilograms of iridium-encapsulated Pu-238 spheres and pellets for use as radioisotope thermal generators, primarily for the space program. The facility is divided between two cell lines, the east cell line used to process powdered Pu-238 oxide raw material into fuel forms and the west cell line used to encapsulate the fuel forms in iridium. Scoping in-situ gamma-ray assays were performed in the PuFF Facility in 2006 and estimated that hundreds of grams of Pu-238 holdup were within the facility. Using this holdup estimate as a source term, SRS has performed a risk analysis that indicated a seismic event that induces a full-facility fire in 235-F could lead to a 28,800 rem dose to a co-located worker. Based on this risk assessment, SRS is taking steps to decontaminate the facility. One of the first steps taken has been to improve upon the quality of the in-situ gamma-ray assay data. Carts and collimators were specially designed to survey the equipment in the PuFF Facility. The cell interiors were assayed along with the furnaces and storage coolers that protrude beneath the cells. While the previous scoping work consisted of 32 measurements, the current series of measurements included nearly 400 measurements using both high-purity germanium and lanthanum bromide detectors. Data analysis for the current set of measurements was conducted with greater rigor as well. MCNP5 was used to evaluate a variety of possible physical distributions for the Pu-238 source term and estimate cross-talk between neighboring cells. Data analysis was performed using three gamma-rays emitted by Pu-238 (99.85 keV, 152.7 keV, and 766.4 keV) providing three independent estimates of the mass of Pu-238 holdup in each of the cells. This also allowed the application of matrix correction factors to adjust gamma-ray attenuation. The weighted mean of these three results was used as the best estimate of Pu-238 holdup in the PuFF facility. This work lowered the estimate of holdup in the PuFF facility by approximately 100 grams compared to the previous estimate, a 0.55's difference. The uncertainty in the Pu-238 holdup was also reduced substantially relative to the 2006 scoping assay. Further radiological measurements are planned for the near future including in-situ gamma-ray assays of wing cabinets in the east cell line maintenance area, the transfer tube between the two cell lines, and some of the furnaces and storage coolers. A germanium gamma imager, the GeGI, will also be used to map out the distribution of the Pu-238 source term in the PuFF Facility. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2019

Radionuclide Behaviour During Thermal Treatment of LLW and ILW Using In-Container Vitrification - 19239

Thermal treatment is being considered in the UK for the treatment of a wide range of low and intermediate level wastes (LLW and ILW). To support this objective, a range of in-container vitrification trials were conducted to test a wide range of simulated waste streams. The vitrified products have been visually inspected and samples removed for chemical analysis. This paper presents preliminary results of this analysis with some comment on the spatial and chemical heterogeneity of the products. Treatment of a sludge simulant in a steel skip failed to fully melt the metal and produced a glass encapsulated waste-form with clearly visible porosity. Clinoptilolite produced a dense uniform glass but with some chemical heterogeneity. Some operational issues were encountered when treating water-rich sludge, but these were successfully resolved and resulted in a broadly homogenous vitrified product. Melting simulated mixed decommissioning waste produced a chemically homogenous product, despite the heterogenous nature of the waste stream. Uranium and concrete contained in a steel 'top hat' presented significant treatment issues. The top hat failed to fully melt, and this appears to have prevented the waste contained within the top hat from mixing with the glass external to the top hat. As with the steel skip containing sludge, this again left a glass encapsulated, rather than fully vitrified, product. Attempts to melt bulk PVC (an analogue of soft PCM) initially led to significant operational issues with the melt being terminated early and the waste apparently combusting rather than melting. This was resolved by pre-treating the PVC by shredding it and mixing this with the frit to give a larger contact area for melting. This approach produced a homogenous well mixed glass. Overall it appears the properties of the melt product are highly dependent on the physical and chemical properties of the waste stream being treated. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Multi-Physics Coupling to Model a RbCl-RbCl-Ga Target Stack

A computational model has been developed to simulate the performance of the Los Alamos Isotope Production Facility's (IPF) routine production target configuration, which consists of two Inconel-encapsulated RbCl salt targets and one niobium-encapsulated gallium target separated by water cooling channels. The methodology involves iteratively coupling particle transport and thermal hydraulic codes to determine the time dependent behavior of the target. Phase and density changes seen in targets are known to impact beam penetration and distribution. In addition, evidence of energy distributions seen in experimental radionuclide yield measurements at IPF do not match those seen in previous MCNP predictions. Density reduction as a result of heat deposition affects proton energy loss along the particle's track, impacting both radionuclide yields and target design. Accurate modeling of the thermal behavior of these multi-phase targets and the corresponding impact on beam behavior will significantly improve our understanding of incident and exit proton energy distributions and resulting radionuclide yields in downstream targets. Thermal hydraulic modeling, including computational fluid dynamics (CFD) and heat transfer, was performed with ANSYS CFX while particle transport was performed with the Monte Carlo N-Particle code (MCNP). (authors)

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2016

The criticality safety program of the Swedish nuclear fuel and waste management Co (SKB)

SKB is co-owned by the owners of the Swedish nuclear power plants (NPP) and is responsible for the back-end of all Swedish spent nuclear fuel and radioactive waste from the Swedish nuclear program. The responsibility starts from when the fuel leaves the NPP and ends at the planned final repository. That means that SKB has the responsible for the safety at the intermediate pool storage (Clab), the encapsulation plant (Clink), the Spent Fuel Repository and the transportation between these sites. In March 2011 SKB applied to the Swedish Radiation Safety Authority (SSM) for a permit to build a final repository for spent fuel and an encapsulation plant (Clink). The application contained a criticality safety analysis for the canisters to be used in Clink and the copper canister to be used in the final repository. In 2012 SSM requested several complements to the criticality safety analysis in the application and about the same time they also required Clab to modernise the Safety Analysis Report. Our owners (the NPPs) had also requested SKB to take care of higher enrichments and higher burnup fuel. A prerequisite to meet this was extended Burnable Absorber credit (peak reactivity) and Burn-up credit. Up to this stage SKB had relied heavily on consultants to do criticality safety analysis and had no specific criticality safety program or methodology. However it was now evident to SKB that we needed to take an overall view on the criticality safety area and not only lift the quality of the actual criticality analysis but also to handle organisational and competence issues. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2024

Overview of Quantum Sensing Materials and Techniques for Energy Sector Applications

The energy sector has become increasingly dependent upon highly sensitive sensing devices for a wide range of applications. Variables such as temperature, pH, electromagnetic fields, ions, and pressure must be measured with high precision, often in harsh conditions (e.g. highly corrosive environments due to high temperature, pressure and humidity). These sensors are deployed in infrastructure such as transformers, pipelines, mines, nuclear power plants, and other areas to ensure safe operating conditions and uninterrupted, optimized service. Moreover, new opportunities for sensors have emerged due to the expansion of smart grids/meters, driverless vehicles, and the discovery of new oil, gas, and critical mineral deposits. The continued maturation of quantum sensing technologies offers exciting opportunities for quantum-enhanced measurements within the energy sector that may provide significant improvements in sensitivity beyond the classical limit. Here, an overview of established and emerging quantum materials for sensing applications will be provided, from trapped ions to color centers in diamond and silicon carbide. Associated quantum sensing methods for these materials will be discussed, with an emphasis on platforms that are nearing commercial viability. Specific application opportunities within the energy sector for quantum sensors will then be analyzed, including oil/gas discovery, greenhouse gas emission monitoring, pH and ion sensing, current measurement in electric vehicle batteries, and quantum-enhanced spectroscopy. Remaining barriers, such as quantum sensor platform miniaturization and ruggedization, will also be analyzed. A specific project at the National Energy Technology Laboratory involving the functionalization of qubits using metal-organic frameworks for enhanced quantum sensing will also be highlighted. Here, nitrogen vacancy centers (NV) in nanodiamonds, a commercially available qubit with long coherence times and utilizable quantum properties at room temperature, are encapsulated in a controlled way using the metal-organic framework ZIF-8. The ZIF-8 provides a well-defined, porous scaffold that can be controlled to promote the selective uptake of specific target analytes, such as gas molecules or ions. The quantum sensing performance of this composite material is either preserved or enhanced following ZIF-8 encapsulation; the optically detected magnetic resonance response of the NV nanodiamonds with and without the ZIF-8 coating are identical, while the ZIF-8 coating increases the longitudinal spin relaxation lifetime (T1) of the NV centers, an important parameter for spin relaxometry-based quantum sensing experiments. Taken together, these results demonstrate the importance of qubit functionalization as a crucial step for rationally designing high performance quantum sensors.

Crawford, Scott↗
DOE OSTI2024

Understanding the Chemical Complexity of Multicomponent Systems: Uranium Polyoxometalates as Nanosorbents

The overarching objective of this project was to develop a molecular-scale understanding of chemical interactions of the transuranic (TRU) elements with uranyl-based polyoxometalate nanoclusters (UPOMs). The specific goals that supported this overarching objective were to: (i) quantify TRU interactions with UPOMs as a function of TRU, carbonate, and UPOM concentration, pH, and temperature; (ii) examine the molecular-level bonding environment of TRU-UPOM complexes; and (iii) develop a rate expression capable of describing the sorption and reduction of TRU by UPOMs. The published literature suggests several potential interactions can occur in TRU-UPOM systems: (i) encapsulation of TRU and coordination with the internal ‘-yl’ oxygens of the UPOM, (ii) coordination of TRU with the external ‘-yl’ oxygens of the UPOM, and (iii) coordination of TRU with the bridging ligands (e.g., peroxo, hydroxo, oxalate) of the UPOM. The latter two may induce aggregation of the UPOMs. The concept of encapsulation is demonstrated by the X-ray diffraction structure of crystallized U 20 , which reveals a Na + cation under each pentagonal face (Sigmon et al., 2009). Computational modeling shows that, while the negative charge of U 20 is spread among all the oxygen atoms, the internal ‘-yl’ oxygens host the most negative charge (Miro and Bo, 2012). This negative charge is reduced through the complexation of the templating sodium ions in the interior of the UPOM. Furthermore, Nyman et al. (2011) shows that cesium can exit through the pentagonal window of U 28 in the aqueous phase, suggesting that the TRU elements, which are smaller than cesium, may be capable of entering a UPOM through these windows in an exchange reaction. Under this project, we focused on hafnium, neptunium, and plutonium interactions with UPOMs.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2024

Crosslinked polymers with tunable coefficients of thermal expansion

Curatives and their resulting thermosets and other crosslinked polymers can reduce thermal expansion mismatch between an encapsulant and objects that are encapsulated. This can be accomplished by incorporating a negative CTE moiety into the thermoset resin or polymer backbone. The negative CTE moiety can be a thermal contractile unit that shrinks as a result of thermally induced conversion from a twist-boat to chair or cis/trans isomerization upon heating. Beyond CTE matching, other potential uses for these crosslinked polymers and thermosets include passive energy generation, energy absorption at high strain rates, mechanophores, actuators, and piezoelectric applications.

Redline, Erica M.↗
DOE OSTI2017

Chapter 10.3: Reliability and Durability of PV Modules

Each year the world invests tens of billions of dollars or euros in PV systems with the expectation that these systems will last approximately 25 years. Although the disciplines of reliability, quality, and service life prediction have been well established for numerous products, a full understanding of these is currently challenging for PV modules because the desired service lifetimes are decades, preventing direct verification of lifetime predictions. A number of excellent reviews can be found in the literature summarizing the types of failures that are commonly observed for PV modules. This chapter discusses key failure/degradation mechanisms selected to highlight how the kinetics of failure rates can and cannot be confidently predicted. For EVA-encapsulated modules, corrosion is observed to follow delamination, which then allows water droplets to directly contact the metallization. Extended test protocols such as Qualification Plus were created to address the known problems while standards groups update standard tests through the consensus process.

14 SOLAR ENERGY↗
DOE OSTI2021

Solvent Impregnated Polymers Loaded with Liquid-Like Nanoparticle Organic Hybrid Materials for Enhanced Kinetics of Direct Air Capture and Point Source CO 2 Capture

Hybrid CO 2 capture materials, solvent impregnated polymers (SIPs), are developed based on a simple and scalable encapsulation technique to enhance CO 2 capture kinetics of water-lean solvents with high viscosity. Liquid-like nanoparticle organic hybrid materials functionalized with polyethylenimine (NOHM-I-PEI) are incorporated into a shell material and UV-cured to produce gas-permeable solid sorbents with uniform NOHMs loading (NPEI-SIPs). The CO 2 capture kinetics of NPEI-SIPs show a remarkable 50-fold increase compared to that of neat NOHM-I-PEI due to a large increase in the NOHMs-CO 2 interfacial surface area provided by the SIP design. The optimum NOHM-I-PEI loading and sorption temperature are found to be ≈49 wt% and 50 °C, respectively, and NPEI-SIPs exhibit great thermal stability over 20 CO 2 capture/sorbent regeneration temperature swing cycles. The pseudoequilibrium CO 2 loadings of NPEI-SIPs under humid conditions are as high as 3.1 mmol CO 2 g -1 NPEI - SIPs for 15 vol% CO 2 (postcombustion capture) and 1.7 mmol CO 2 g -1 NPEI - SIPs for 400 ppm (direct air capture). Overall, these findings suggest that NPEI-SIPs can effectively capture CO 2 from a wide range of CO 2 concentrations including direct air capture while allowing the flexible design of CO 2 capture reactors by combining the benefits of liquid solvents and solid sorbents.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Synthesis of Red, Green, and Blue Carbon Quantum Dots and Construction of Multicolor Cellulose-Based Light-Emitting Diodes

Light-emitting diodes (LEDs) are widely used in lighting and display applications. Carbon quantum dots (CQDs), which have high biocompatibility, high resistance to photobleaching, and full-spectrum luminescence, have inherent advantages as fluorescent materials for LED devices. Herein, multicolor CQDs are prepared by a new reagent engineering strategy due to the difference of effective conjugate length and the surface electron-withdrawing groups of CQDs. White CQDs are realized by mixing blue, green, and red CQDs proportionally. Then, the aggregation-caused quenching phenomenon of CQDs is suppressed through the hydrogen-bonding network of cellulose nanofibrils (CNFs). Multicolor fluorescent films are prepared from CQDs and CNFs by simple mixing and casting methods. Finally, thin-film encapsulation based on the photosensitive resin ABPE-10 coating can be realized and rapidly assembles into fluorescent films with different light-emitting colors into LED devices, leading to have superior thermal performance compared with conventional LEDs. White LEDs have excellent white-light illumination performance, with Commission Internationale de L’Eclairage color coordinates of (0.33, 0.37), a correlated color temperature of 5688 K, and a color rendering index of 86. This strategy provides a convenient and scalable pathway for low-cost, environmentally friendly, and high-performance CQDs-based LEDs.

42 ENGINEERING↗
DOE OSTI2018

Effect of Silver Doped Zinc Oxide as Nanofiller for the Development of Biopolymer Nanocomposites from Chitin and Cashew Gum

Nanocomposites based on chitin (CT) and cashew gum (CG) with different concentrations of silver doped zinc oxide nanoparticles (Ag–ZnO) were prepared and characterized by FTIR, UV, XRD, TEM, SEM, DSC, TGA, electrical conductivity measurements. FTIR spectra showed that the characteristic absorption band of the blend was shifted to a higher frequency in nanocomposites, indicating the intermolecular interaction between the blend and nanoparticles. The change in the UV absorption of nanocomposites relative to that of pure blend indicated the successful encapsulation of crystalline metal oxide nanoparticles in the blend matrix. XRD patterns showed that the diffraction peak of the composites were shifted near to the metal oxide peak which indicated that the surface of Ag–ZnO was perpendicular to CT/CG and changed from a semi-crystalline nature to a crystalline structure. The morphological analysis using SEM and TEM showed a uniform attachment of nanoparticles within the CT/CG blend. DSC analysis showed the increased glass transition temperature by the addition of nanoparticles. Thermal stability of nanocomposites was higher than the blend and thermal stability increased with an increase in the content of nanoparticles. The different electrical properties such as AC conductivity and dielectric behaviour of the composites were increased with an increased loading of nanoparticles.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Maximum Endurance Lightning Current of Different High-Temperature Superconducting Wires

The over-current performance of high-temperature superconductors (HTSs) has been well studied. However, the superconducting devices used in power grid might also suffer lightning current. In previous researches, we have investigated the influences of the substrate layer, encapsulation layer, and tape dimension on the thermal stability of yttrium barium copper oxide (YBCO) tapes after suffering a lightning current. However, in this paper, we will focus on the maximum endurance lightning currents (MELCs) of different HTS tapes including YBCO and BSCCO tapes. We prepared and tested seven HTS samples. The critical current and n value of each sample were measured and calculated before and after the 8/20-μs lightning current tests. A maximum endurable value of lightning current which might not cause the critical current degradation was obtained from the testing results. Finally, the mechanisms causing the degradation were analyzed.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Sulfide treatment passivation of mid-/long-wave dual-color infrared detectors based on type-II InAs/GaSb superlattices

The surface passivation of mid-/long-wave dual-color infrared detectors based on type-II InAs/GaSb superlattices(T2SLs) photodetectors employing diverse voltage and current conditions of sulfide treatment passivation was presented. The superlattices were grown on GaSb substrate by molecular beam epitaxy technology. The circle pixel devices in the diameter of 200 μm with 5 μm at mid-infrared and 14 μm at long-infrared 100% cutoff wavelength were fabricated. Compared to only SiO{sub 2} encapsulation passivation and unpassivated detectors, the dark current density, which takes into account surface leakage current, was reduced by approximately three orders of magnitude and the R0A-product was six times higher by sulfide treatment. Besides, detectors passivated through 22 V 15 mA sulfur treated, the responsivity of was 0.95A/W and QE was 0.44 at 2.6 μm. As for the wavelength of 5.3 μm, the responsivity and QE were 1.95 A/W and 0.45 severally.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Characteristics of Non-metallic Inclusions in Steel Obtained from Different-Sized Samplers

To determine the effect of sampler size on the detection of inclusions in liquid steel, four different-sized samplers were designed for industrial sampling from a continuous casting tundish. The samples were evaluated via scanning electron microscopy and energy-dispersive spectroscopy. With increasing sample size, the cooling rate of the sample and velocity for particle engulfment decreased. The extent of encapsulation of complex inclusions increased from 0 pct with the smallest sampler to 48.2 pct with the largest sampler. In the samplers that cooled at 41.2 and 26.7 K s{sup −1}, the major inclusions were calcium aluminates; in the larger samplers, which cooled more slowly at 8.2 and 1.0 K s{sup −1}, the complex inclusions predominately comprised Al{sub 2}O{sub 3} + (Ca, Mn)S and Al{sub 2}O{sub 3} + CaS, respectively. The sizes of the sulfides gradually increased with increasing sampler size; for example, the sulfide average diameter increased from 2.5 to 3.5 μm when the sampler inner diameter increased from 50 to 70 mm. The main direction of movement of the inclusions during the sampling process was upward.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Toxicological assessment of mesoporous silica particles in the nematode Caenorhabditis elegans

Highlights: • C. elegans is a suitable in vivo model to evaluate the toxicity of MSPs. • MSPs are well-ingested and located along the gastrointestinal tract of C. elegans. • Evaluation of lifespan and healthspan demonstrate the safety of micro-sized MSPs. • Nano-sized particles have a negative impact on C. elegans lifespan and healthspan. • Functionalization of nanoparticles’ surface reduces their toxicity in C. elegans. Here we report the toxicological evaluation of mesoporous silica particles (MSPs) in the nematode C. elegans. Specifically, we have investigated the effect of bare micro- (M0) and nano-sized (N0) MSPs, and their corresponding functionalized particles with a starch derivative (Glu-N) (M1 and N1, respectively) on C. elegans ageing parameters. The toxicity of MSPs, their impact on C. elegans lifespan, movement capacity, progeny and ability to survive upon exposure to acute oxidative stress were assessed. This study demonstrated that both size particles assayed (M0 and N0), labeled with rhodamine and monitored through fluorescence microscopy, are ingested by the nematode. Moreover, toxicity assays indicated that bare nano-sized particles (N0) have a negative impact on the C. elegans lifespan, reducing mobility and progeny production. By contrast, micro-sized particles (M0) proved innocuous for the nematodes. Furthermore, functionalization of nanoparticles with starch derivative reduced their toxicity in C. elegans. Thus, oral intake of N1 comparatively increased the mean lifespan and activity rates as well as resistance to oxidative stress. The overall findings presented here demonstrate the influence of MSP size and surface on their potential toxicity in vivo and indicate the silica-based mesoporous particles to be a potential support for encapsulation in oral delivery applications. Furthermore, the good correlation obtained between healthy aging variables and viability (mean lifespan) validates the use of C. elegans as a multicellular organism for nanotoxicology studies of MSPs.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Novel in-capsule synthesis of metal–organic framework for innovative carbon dioxide capture system

Metal-Organic Frameworks (MOFs) have been developed as solid sorbents for CO2 capture applications and their properties can be controlled by tuning the chemical blocks of their crystalline units. A number of MOFs (e.g., HKUST-1) have been developed but the question remains how to deploy them for gas–solid contact. Unfortunately, the direct use of MOFs as nanocrystals would lead to serious problems and risks. Here, for the first time, we report a novel MOF-based hybrid sorbent that is produced via an innovative in-situ microencapsulated synthesis. Using a custom-made double capillary microfluidic assembly, double emulsions of the MOF precursor solutions and UV-curable silicone shell fluid are produced. Subsequently, HKUST-1 MOF is successfully synthesized within the droplets enclosed in the gas permeable microcapsules. The developed MOF-bearing microcapsules uniquely allow the deployment of functional nanocrystals without the challenge of handling ultrafine particles, and further, can selectively reject undesired compounds to protect encapsulated MOFs.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗