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At least 1,765 records · Page 98
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Midmorning Point Sampling May Not Accurately Represent Nitrous Oxide Emissions Following Fertilizer Applications

A common approach for measuring N 2 O emissions is to collect midmorning or early evening gas samples from experiments utilizing the chamber-based flux methodology. However, due to high spatial and temporal variability, N 2 O estimates based on midmorning or early evening sampling may not provide accurate estimates of total emissions. This study determined the impact of sampling collection timing on the precision and accuracy of N 2 O emissions estimates. Nitrous oxide emissions, air and soil temperatures, and soil moisture were measured for 21 d following the application of 224 kg urea-N ha –1 on 20 Sept. 2017, 11 Oct. 2017, and 1 May 2018, at six time intervals (0130–0230, 0530–0630, 0930–1030, 1330–1430, 1730–1830, and 2130–2230 h) over a 24-h period. Based on multiple daily measurements, point samples collected between 0930 and 1030 h (midmorning) were inconsistent in their ability to predict N 2 O emissions. However, samples collected between 2130 and 2230 h (early evening) were similar to average emissions. The number of randomly collected point samples to be within 20% of the mean 80% of the time over a 21-d period ranged from 13 samples for fertilizer applied on 20 Sept. 2017 to 48 samples for fertilizer applied on 11 Oct. 2017. This research indicates that management and climatic variability affect N 2 O emissions, and that accurate sampling protocols vary across management and climates. To reduce uncertainty, N 2 O sampling protocol should be tested under conditions likely to occur and where possible, near-continuous measurement systems should be adopted.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2013

Discovery of the First Leaking Double-Shell Tank - Hanford Tank 241-AY-102

Full text - Long Abstract. A routine video inspection of the annulus region of double-shell tank 241-A Y-102 in August of 2012 indicated the presence material in the annulus space between the primary and secondary liners. A comparison was made to previous inspections performed in 2006 and 2007. which indicated that a change had occurred. The material was observed at two locations on the floor of the annulus and one location at the top of the annulus region where the primary and secondary top knuckles meet (RPP-ASMT-53793). Subsequent inspections were performed. leading to additional material observed on the floor of the annulus space in a region that had not previously been inspected (WRPS-PER-2012-1363). The annulus Continuous Air Monitor (CAM) was still operational and was not indicating elevated radiation levels in the annulus region. When the camera from the inspections was recovered. it also did not indicate increased radiation above minimum contamination levels (WRPS-PER-2012-1363). A formal leak assessment team was established August 10, 2012 to review tank 241-AY-102 construction and operating histories and to determine whether the material observed in the annulus had resulted from a leak in the primary tank. The team consisted of individuals from Engineering. Base Operations and Environmental Protection. As this was a first-of-its-kind task. a method for obtaining a sample of the material in the annulus was needed. The consistency of the material was unknown.and the location of a majority of the material was not conducive to using the sampling devices that were currently available at Hanford. A subcontractor was tasked with the development fabrication.and testing of a sampling device that would be able to obtain multiple samples from the material on the annulus floor. as well as the material originating from a refractory air-slot near the floor of the annulus space. This sampler would need to be able to collect and dispense the material it collected into a sample jar retrieval device for transportation of the material to the 222-S laboratory on the Hanford site for analysis. The subcontractor agency fabricated a remote underground sampler by modifying off-the-shelf robotics and parts. Limited testing of the sampler was conducted using a mock-up of the tank annulus and one simulated material type -a salt block. The mock-up testing indicated that the sampler would be able to maneuver within the confined space and that the device worked with full functionality. A total of six weeks had passed from initiation to implementation of the new sampler in the 241-AY-102 tank annulus. Initial sample material was obtained from the annulus floor using the Off-Riser Sampler System that has been used at Hanford tor years to obtain material from the primary tanks. This could be used at the location near Riser 83 since the material was collected directly from the annulus floor and not from a location on the wall or behind a pipe, as was needed from the two locations near Riser 90. After obtaining a small sample of the material on the annulus floor.this sampler sustained terminal damage due to conduit pipes it had to transverse in order to collect and recover material from this location. Several issues were also encountered during deployment of the new sampler into the annulus near Riser 90. These included: Difficulty fitting the sampler down the 12-inch riser into the annulus due to a small tolerance in the size of the sampler; Failure of sampler components and functions during deployment including the camera. pneumatics.and bearing seals; Delays in the field due to supporting equipment issues including cables. cameras. and scaffolding; and, Low recovery of sample material obtained for analysis. The complications that occurred during deployment and use of the new sampler during the sampling event ultimately resulted in lower recovery of material from these locations in the annulus than was obtained using the Off-Riser Sampler System and limited the analyses that could be performed for determining the origin of the material. Following completion of the sample analyses and the assessment of its construction history and use. there was a consensus among the leak assessment team members that two of the three materials sampled from the annulus floor region were the result of waste leaking from a breach in the primary tank. The probable leak cause was identified as corrosion at high temperatures in a tank whose containment margins had been reduced due to construction difficulties (RPP-ASMT-53793). A formal Lessons Learned was created concerning designing equipment tor unique purposes under time constraints. This document was published in OPEXShare on May 20. 2013. It highlighted some of the issues that arose with the subcontractor sampler development and provided recommendations to prevent a recurrence should this task need to be performed again in the future. The document can be found at http://msa.hanford.gov/opex/lesson.cfm/2013/5/20/3481/AY-102-Annulus-Sampler-Designing-Equipment-for-Unique-Purposes-under-Time-Constraints/.

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

Unraveling the origin of air-stability in single-crystalline layered oxide positive electrode materials

Single-crystalline Ni-rich layered oxides present compelling advantages over conventional polycrystalline counterparts toward large-scale applications, including enhanced mechanical stability and higher energy density. Nevertheless, the deleterious effects of air exposure, which is inevitable in industrial processing, on their structure and electrochemical performance remain poorly understood. Herein, we reveal that air exposure is more detrimental to the electrochemical performance of single-crystalline layered oxide positive electrodes than polycrystalline counterparts. It is found that air-induced surface structural distortions are primarily responsible for the electrochemical performance decay of single-crystalline samples rather than the generally believed surface residual lithium. Leveraging multiscale diffraction and imaging techniques, we identify an undesirable structural transition to a metastable O1* phase, which introduces substantial lattice defects and localized strain concentrations within the layered structure. These adverse structural evolutions compromise structural integrity and promote crack initiation during electrochemical cycling, ultimately accelerating capacity fade. Our findings provide critical insights into the air-induced degradation mechanisms and emphasize the urgent need for developing effective stabilization strategies to facilitate the commercial implementation of single-crystalline Ni-rich positive electrodes.

36 MATERIALS SCIENCE↗
NASA NTRS1975

Interaction of gases with lunar materials

The surface properties of lunar fines were investigated. Results indicate that, for the most part, these properties are independent of the chemical composition and location of the samples on the lunar surface. The leaching of channels and pores by adsorbed water vapor is a distinguishing feature of their surface chemistry. The elements of air, if adsorbed in conjunction with water vapor or liquid water, severely impedes the leaching process. In the absence of air, liquid water is more effective than water vapor in attacking the grains. The characteristics of Apollo 17 orange fines were evaluated and compared with those of other samples. The interconnecting channels produced by water vapor adsorption were found to be wider than usual for other types of fines. Damage tracks caused by heavy cosmic ray nuclei and an unusually high halogen content might provide for stronger etching conditions upon exposure to water vapor.

Holmes, H. F.↗
DOE OSTI2017

Laser Ablation Molecular Isotopic Spectrometry for Molecules Formation Chemistry in Femtosecond-Laser Ablated Plasmas

Recently, laser ablated molecular isotopic spectrometry (LAMIS) has expanded its capability to explore molecules formation mechanism in laser-induced plasma in addition to isotope analysis. LAMIS is a powerful tool for tracking the origination of atoms that is involved in formation of investigated molecules by labeling atoms with their isotopic substitution. The evolutionary formation pathways of organic molecules, especially of C 2 dimers and CN radicals, were frequently reported. However, very little is known about the formation pathways for metallic radicals and heterodimers in laser ablated plasma. This research focuses on elucidating the formation pathways of AlO radicals in femtosecond laser ablated plasma from 18 O-labeled Al 2 O 3 pellet. Plasmas expanding with strong forward bias in the direction normal to the sample surface were generated in the wake of a weakly ionized channel created by a femtosecond laser. The formation mechanism of AlO and influence of air were investigated with multiple plasma diagnostic methods such as monochromatic fast gating imaging, spatiotemporal resolved optical emission spectroscopy, and LAMIS. An advanced LAMIS fitting procedure was used to deduce the spatiotemporal distributions of Al 18 O and Al 16 O number densities and also their ratios. We found that the Al 16 O/Al 18 O number density ratio is higher for plasma portion closer to the sample surface, which suggests that chemical reactions between the plasma plume and ambient air are more intense at the tail of the plasma. The results also reveals that direct association of free Al and O atoms is the main mechanism for the formation of AlO at the early stage of the plasma. Finally, to the contrast, chemical reactions between plasma materials and ambient oxygen molecules and the isotope exchange effect are the dominant mechanisms of the formation of AlO and evolution of Al 16 O/Al 18 O number density ratio at the late stage of the plasma.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Structural and physical properties of Re substituted B-site ordered and disordered SrCo{sub 1-x}Re{sub x}O{sub 3-{delta}} (x=0.1, 0.25, 0.5)

Synthesis conditions, structural, magnetic and transport properties have been studied for SrCo{sub 1-x}Re{sub x}O{sub 3-{delta}} samples with x=0.1, 0.25, 0.5. SrCo{sub 0.9}Re{sub 0.1}O{sub 3-{delta}} forms in air and remains stable on cooling indicating that small amounts of Re{sup 7+} stabilize a B-site disordered Pm-3m phase inhibiting formation of a hexagonal phase observed for SrCoO{sub 3-{delta}}. After oxygenation SrCo{sub 0.9}Re{sub 0.1}O{sub 2.94} becomes ferromagnetic below 125 K and shows metallic-like conductivity with moderate magnetoresistance at low temperatures. Fully oxygenated double perovskite Sr{sub 2}CoReO{sub 6} (x=0.5) forms under reducing conditions and is tetragonal at room temperature. A hysteretic transition to the antiferromagnetic state at low temperatures ({approx}50-60 K) is coupled with a drastic change of electronic and thermal properties. Contrary to previous reports [A. Nag et al., Chem. Mater. 20(13) (2008) 4420-4424] SrCo{sub 0.75}Re{sub 0.25}O{sub 3} is not a partially cation ordered Sr{sub 4}Co{sub 3}ReO{sub 12} phase, but a mixture of two structural and magnetic phases with disordered SrCo{sub 1-xd}Re{sub xd}O{sub 3} and ordered SrCo{sub 1-xo}Re{sub xo}O{sub 3} compositions where xd>0.1 and xo<0.5. - Graphical abstract: Neutron diffraction pattern for SrCo{sub 0.75}Re{sub 0.25}O{sub 3}. SrCo{sub 0.75}Re{sub 0.25}O{sub 3} is not a partially cation ordered Sr{sub 4}Co{sub 3}ReO{sub 12} phase, but a mixture of two structural and magnetic phases with disordered SrCo{sub 1-xd}Re{sub xd}O{sub 3} and ordered SrCo{sub 1-xo}Re{sub xo}O{sub 3} compositions where xd>0.1 and xo<0.5. Highlights: Black-Right-Pointing-Pointer SrCo{sub 0.9}Re{sub 0.1}O{sub 2.94} is a B-site disordered cubic Pm-3m phase. Black-Right-Pointing-Pointer SrCo{sub 0.9}Re{sub 0.1}O{sub 2.94} is ferromagnetic below 125 K with metallic-like conductivity. Black-Right-Pointing-Pointer Sr{sub 2}CoReO{sub 6} is tetragonal at room temperature and antiferromagnetic below {approx}50-60 K. Black-Right-Pointing-Pointer SrCo{sub 0.75}Re{sub 0.25}O{sub 3} is not a partially cation ordered Sr{sub 4}Co{sub 3}ReO{sub 12} phase. Black-Right-Pointing-Pointer SrCo{sub 0.75}Re{sub 0.25}O{sub 3} is a mixture of disordered and ordered perovskites.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2011

Air Corrosivity in U.S. Outdoor-Air-Cooled Data Centers is Similar to That in Conventional Data Centers

There is a concern that environmental-contamination caused corrosion may negatively affect Information Technology (IT) equipment reliability. Nineteen data centers in the United States and two in India were evaluated using Corrosion Classification Coupons (CCC) to assess environmental air quality as it may relate IT equipment reliability. The data centers were of two basic types: closed and outside-air cooled. A closed data center provides cool air to the IT equipment using air conditioning in which only a small percent age of the recirculation air is make-up air continuously supplied from outside to meet human health requirements. An outside-air cooled data center uses outside air directly as the primary source for IT equipment cooling. Corrosion measuring coupons containing copper and silver metal strips were placed in both closed and outside-air cooled data centers. The coupons were placed at each data center (closed and outside-air cooled types) with the location categorized into three groups: (1) Outside - coupons sheltered, located near or at the supply air inlet, but located before any filtering, (2) Supply - starting just after initial air filtering continuing inside the plenums and ducts feeding the data center rooms, and (3) Inside located inside the data center rooms near the IT equipment. Each coupon was exposed for thirty days and then sent to a laboratory for a corrosion rate measurement analysis. The goal of this research was to investigate whether gaseous contamination is a concern for U.S. data center operators as it relates to the reliability of IT equipment. More specifically, should there be an increased concern if outside air for IT equipment cooling is used To begin to answer this question limited exploratory measurements of corrosion rates in operating data centers in various locations were undertaken. This study sought to answer the following questions: (1) What is the precision of the measurements (2) What are the approximate statistical distributions of copper and silver corrosion rates in the sampled data centers(3) To what extent are copper and silver corrosion measurements related (4) What is the relationship of corrosion rate measurements between outside-air cooled data centers compared to closed data centers (5) How do corrosivity measurements relate to IT equipment failure rates The data from our limited sample size suggests that most United States data center operators should not be concerned with environmental gaseous contamination causing high IT equipment failure rates even when using outside-air cooling. The research team recommends additional basic research on how environmental conditions, specifically gaseous contamination, affect electronic equipment reliability.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
NASA NTRS2018

Shifting Data Collection from a Fixed to an Adaptive Sampling Paradigm

For domains where data are difficult to obtain due to human or resource limitations, an emphasis is needed to efficiently explore the dimensions of information spaces to acquire any given response of interest. Many disciplines are still making the transition from brute force, dense, full factorial exploration of their information spaces to a more efficient design of experiments approach; the latter being in use successfully for many decades in agricultural and automotive applications. Although this transition is still incomplete, groundwork must be laid for incorporating the next generation of algorithms to adaptively explore the information space in response to data collected, as well as any resulting empirical models (i.e., metamodels). The methodology in the present work was to compare metamodel quality using a fixed sampling technique compared to an adaptive sampling technique based on metamodel variance. In order to quantify metamodeling errors, a delta method was used to provide quantitative model variance estimates. The present methodology was applied to a design space with an air-breathing engine performance response. It was shown that competitive metamodel quality with lower associated error could be achieved for an adaptive sampling technique for the same level of effort as a fixed, a priori sampling technique.

Axdahl, Erik L.↗
DOE OSTI2014

Tuning of deep level emission in highly oriented electrodeposited ZnO nanorods by post growth annealing treatments

Highly dense and c-axis oriented zinc oxide (ZnO) nanorods with hexagonal wurtzite facets were deposited on fluorine doped tin oxide coated glass substrates by a simple and cost-effective electrodeposition method at low bath temperature (80 °C). The as-grown samples were then annealed at various temperatures (T{sub A} = 100–500 °C) in different environments (e.g., zinc, oxygen, air, and vacuum) to understand their photoluminescence (PL) behavior in the ultra-violet (UV) and the visible regions. The PL results revealed that the as-deposited ZnO nanorods consisted of oxygen vacancy (V{sub O}), zinc interstitial (Zn{sub i}), and oxygen interstitial (O{sub i}) defects and these can be reduced significantly by annealing in different environments at optimal annealing temperatures. However, the intensity of deep level emission increased for T{sub A} greater than the optimized values for the respective environments due to the introduction of various defect centers. For example, for T{sub A} ≥ 450 °C in the oxygen and air environments, the density of O{sub i} defects increased, whereas, the green emission associated with V{sub O} is dominant in the vacuum annealed (T{sub A} = 500 °C) ZnO nanorods. The UV peak red shifted after the post-growth annealing treatments in all the environments and the vacuum annealed sample exhibited highest UV peak intensity. The observations from the PL data are supported by the micro-Raman spectroscopy. The present study gives new insight into the origin of different defects that exist in the electrodeposited ZnO nanorods and how these defects can be precisely controlled in order to get the desired emissions for the opto-electronic applications.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Impact of Natural Gas Appliances on Pollutant Levels in California Homes

This report presents results from the first year of a 2-year study, investigating associations of five air pollutants (CO, NO 2 , NO X , formaldehyde and acetaldehyde) with the presence of natural gas appliances in California homes. From November 2011 to March 2012, pollutant concentration and occupant activity data were collected in 155 homes for 6-day periods. The sample population included both single-family (68%) and multi-family (32%) dwellings, with 87% having at least one gas appliance and 77% having an unvented gas cooking appliance. The geometric mean (GM) NO 2 levels measured in the kitchen, bedroom and outside of homes were similar at values of 15, 12 and 11 ppb, respectively. In contrast, the GM NO X levels measured in the kitchen and bedroom of homes were much higher than levels measured outdoors, at levels of 42 and 41 ppb, compared to 19 ppb, respectively. Roughly 10% of sampled homes had 6-day average NO2 levels that exceeded the outdoor annual average limit set by the California Ambient Air Quality Standards (CAAQS) (30 ppb). The GMs of the highest 1-h and 8-h CO level measured in homes were 2.5 and 1.1 ppm, respectively. Four homes had a 1-h or 8-h concentration that exceeded the outdoor limits set by the CAAQS. The GM formaldehyde and acetaldehyde concentrations measured in homes were 15 and 7 ppb, respectively. Roughly 95% of homes had average formaldehyde levels indoors that exceeded the Chronic Reference Exposure Level set by the California EPA (7 ppb). Concentrations of NO 2 and NO X , and to a lesser extent CO were associated with use of gas appliances, particularly unvented gas cooking appliances. Based on first principles, it is expected that effective venting of cooking pollutant emissions at the source will lead to a reduction of pollutant concentrations. However, no statistical association was detected between kitchen exhaust fan use and pollutant concentrations in homes in this study where gas cooking occurred frequently. The lack of statistical

03 NATURAL GAS↗
DOE OSTI2014

SRS Tank 38H and 43H Supernate Foaming Studies and Tank 38H Reel Tape Solids Characterization

Radioactive waste samples retrieved from Savannah River Site (SRS) Tanks 38H and 43H (concentrate receipt and feed tanks, respectively, for the 2H Evaporator system) were evaluated with regard to their tendency to form foams during air sparging. This work was conducted due to recent processing issues and outages in the evaporator that were believed to have resulted from sample foaming. The samples evaluated for foam formation included supernate collected in April of 2014 (near the time of the evaporator outage) as well as historical samples available within the SRNL shielded cells facility. The April samples included one Tank 43H surface sample (HTF-43-14-42), one Tank 43H sub-surface sample (HTF-43-14-43), and one Tank 38H (HTF-38-14-41) surface sample. In addition, two Tank 43H samples (HTF-43-14-8 and HTF-43-14-9) and one Tank 38H sample (HTF-38-14-6) were also evaluated along with a blended sample of various historical Tank 38H and 43H samples. Characterization results for the April samples are also provided. The composition of the samples was similar to historical evaporator system samples received at SRNL.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS1976

The measurement of carbon monoxide and methane in the national capital air quality control region. III - Correlation interferometer results

Two types of experiments were performed with a correlation interferometer on-board a Bell Jet Ranger 206 Helicopter. The first consisted of simultaneous ground- and air-truth measurements as the instrumented helicopter passed over the Cheverly site. The second consisted of several measurement flights in and around the national capital air quality control region (Washington, D.C.). The correlation interferometer data, the infrared Fourier spectrometer data, and the integrated altitude sampling data showed agreement within the errors of the individual measurements. High values for CO were found from the D.C. flight data to be reproducible and concentrated in areas of stop-and-go traffic. It is concluded, that pollutants at low altitudes are detectable from an air-borne platform by remote correlation interferometry and that the correlation interferometer measurements agree with ground- and air-truth data.

Goldstein, H. W.↗
NASA NTRS2006

Molecular Rayleigh Scattering Diagnostic for Dynamic Temperature, Velocity, and Density Measurements

A molecular Rayleigh scattering technique is developed to measure dynamic gas temperature, velocity, and density in unseeded turbulent flows at sampling rates up to 16 kHz. A high power CW laser beam is focused at a point in an air jet plume and Rayleigh scattered light is collected and spectrally resolved. The spectrum of the light, which contains information about the temperature and velocity of the flow, is analyzed using a Fabry-Perot interferometer. The circular interference fringe pattern is divided into four concentric regions and sampled at 1 and 16 kHz using photon counting electronics. Monitoring the relative change in intensity within each region allows for measurement of gas temperature and velocity. Independently monitoring the total scattered light intensity provides a measure of gas density. A low speed heated jet is used to validate the measurement of temperature fluctuations and an acoustically excited nozzle flow is studied to validate velocity fluctuation measurements. Power spectral density calculations of the property fluctuations, as well as mean and fluctuating quantities are presented. Temperature fluctuation results are compared with constant current anemometry measurements and velocity fluctuation results are compared with constant temperature anemometry measurements at the same locations.

Mielke, Amy R.↗
DOE OSTI2012

Thermoelectric properties and impedance spectroscopy of polycrystalline samples of the beta-gallia rutile intergrowth, (Ga,In){sub 4}(Sn,Ti){sub 5}O{sub 16}

Polycrystalline samples of Ga{sub 3}In(Sn{sub 1-y}Ti{sub y}){sub 5}O{sub 16}, y{<=}0.3 were prepared by solid-state synthesis and characterized to determine their optical properties, thermoelectric properties and electrical impedance. Using diffuse reflectance data and assuming a direct band gap, the band gap of the material ranges from 3.58 eV for y=0 to 3.74 eV for y=0.2. The dc conductivity decreased with increasing Ti content and was thermally activated, ranging from {<=}10{sup -5} S/cm at 300 Degree-Sign C to 0.03 S/cm at 1000 Degree-Sign C for Ga{sub 3}InSn{sub 5}O{sub 16}. The Seebeck coefficient was negative indicating n-type conduction. The activation energies for dc conduction and thermopower were similar, ranging from 1.4{+-}0.1 eV for y=0 to 1.8{+-}0.2 eV for y=0.2, suggesting band conduction. The thermal conductivity of Ga{sub 3}InSn{sub 5}O{sub 16} ranged from 1.1 W/m K at 500 {sup o}C to 0.75 W/m K at 800 Degree-Sign C. The highest figure of merit measured was 2 Multiplication-Sign 10{sup -4} at {approx}900 Degree-Sign C, which is much lower than desired for thermoelectric materials. A comparison of dc conductivity and impedance data indicated a substantial ionic contribution for samples containing titanium. - Graphical abstract: The thermoelectric properties of polycrystalline Ga{sub 3}In(Sn{sub 1-y}Ti{sub y}){sub 5}O{sub 16}, y{<=}0.3 were measured in air at 300-900 Degree-Sign C. The materials are broad-band n-type semiconductors with non-negligible ionic conduction for samples prepared with y>0. The thermoelectric figure of merit is much lower than desired for practical thermoelectric devices. Highlights: Black-Right-Pointing-Pointer Ga{sub 3}In(Sn{sub 1-y}Ti{sub y}){sub 5}O{sub 16}, y{<=}0.2 is a broad-band n-type semiconductor. Black-Right-Pointing-Pointer The conductivity of Ti-containing samples show evidence of an ionic as well as an electronic contribution. Black-Right-Pointing-Pointer The thermal conductivity of polycrystalline Ga{sub 3}In(Sn{sub 1-y}Ti{sub y}){sub 5}O{sub 16} decreases with increasing temperature. Black-Right-Pointing-Pointer The thermoelectric figure of merit for Ga{sub 3}In(Sn{sub 1-y}Ti{sub y}){sub 5}O{sub 16} is lower than desired for practical thermoelectric devices.

36 MATERIALS SCIENCE↗
NASA NTRS2002

The Effects of Substrate Material and Thermal Processing Atmosphere on the Strength of PS304: A High Temperature Solid Lubricant Coating

PS304, a plasma spray deposited solid lubricant coating developed for high temperature sliding contacts was deposited on nine different substrate metals, heat treated at 650C in either air or argon and subsequently tested for strength using a commercially available pull-off adhesion test. Some samples were examined metallographically to help elucidate and explain the results. As deposited coatings exhibit pull-off strengths typically between 16 and 20 MPa with failure occuring (cohesively) within the coating. Heat treatment in argon at 650 C results in a slight increase in coating (cohesive) strength of about 30 percent to 21 to 27 MPa. Heat treatment in air at 650 C results in a dramatic increase in strength to over 30 MPa, exceeding the strength of the epoxy used in the pull test. Cross section metallographic analyses show that no microstructural coating changes occur following the argon heat treatments, however, exposure to air at 650C gives rise to the formation of a second chromium-rich phase precipitate within the PS304 NiCr constituent which provides a strengthening effect and a slight (approximately 5 percent) coating thickness increase. Subsequent heat treatments do not result in any further coating changes. Based upon these studies, PS304 is a suitable coating for use on a wide variety of high temperature substrates and must be heat treated following deposition to enhance strength and ensure dimensional stability.

DellaCorte, Christopher↗
DOE OSTI2018

Systemic inflammatory markers associated with cardiovascular disease and acute and chronic exposure to fine particulate matter air pollution (PM2.5) among US NHANES adults with metabolic syndrome

Highlights: • A cross sectional study of the effect of PM{sub 2.5} AP on inflammatory biomarkers among NHANES participants was conducted. • Participants’ Census tract of residence was linked to USEPA downscaler modeled air pollution for the continental US. • Goal was the assessment of susceptibility of adults with metabolic syndrome to PM2.5 exposure and levels of CRP and WBC. • There was a significant effect of PM2.5 at lag day 0; a 10 µg/m3 rise was associated with a 10.1% increase in CRP level. • There were no significant associations with CRP or WBC for those without metabolic syndrome. There has been no investigation to date of adults with metabolic syndrome examining the association of short and long-term exposure to fine particulate matter (PM{sub 2.5}) air pollution with cardiovascular-disease related inflammatory marker (WBC and CRP) levels in a nationally representative sample. The goal of this study is to assess the susceptibility of adults with metabolic syndrome to PM{sub 2.5} exposure as suggested by increased cardiovascular-disease related inflammatory marker levels.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2014

Iodine Loading of NO Aged Silver Exchanged Mordenite

In an off-gas treatment system for used nuclear fuel processing, a solid sorbent will typically be exposed to a gas stream for months at a time. This gas stream may be at elevated temperature and could contain water vapor, gaseous nitrogen oxides (NO{sub x}), nitric acid vapors, and a variety of other constituents. For this reason, it is important to evaluate the effects of long-term exposure, or aging, on proposed sorbents. Silver exchanged mordenite (AgZ) is being studied at Oak Ridge National Laboratory (ORNL) to determine its iodine sorption capacity after long term exposure to increasingly more complex chemical environments. Studies previously conducted at ORNL investigated the effects of aging reduced silver exchanged mordenite (Ag{sup 0}Z) in dry air, moist air, and NO2. This study investigated the effects of extended exposure to nitric oxide (NO) gas on the iodine capture performance of Ag{sup 0}Z. A deep bed of Ag{sup 0}Z was aged in a 1% nitric oxide (NO) air stream, and portions of the bed were removed at pre-determined intervals. After being removed from the NO stream, each sample was loaded with iodine in a thin bed configuration. These samples were analyzed by neutron activation analysis (NAA) to quantify the iodine content in the sample. Samples were removed at one week and one month. A 78% decrease in sample capacity was seen after one week of exposure, with no further decrease observed after 1 month of aging. The observed loss in capacity is larger in magnitude than previous studies exposing Ag{sup 0}Z to dry air, moist air, or NO2 gas. The aging study was terminated after one month and repeated; this successfully demonstrated the reproducibility of the results.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2018

Characterisation and heat treatment of chloride-contaminated and humidified PuO2 samples

To mimic the reactions that have occurred between plutonium dioxide (PuO2) and degraded polyvinyl chloride during prolonged storage, batches of PuO2 powders with varying specific surface area (4-38m2 g1) were exposed to dry hydrogen chloride gas forming a surface-sorbed exchangeable chloride species that was readily leached by dilute caustic solution. One batch was also humidified under a 95% relative humidity atmosphere. Heat treatment at temperatures between 100 and 950 C steadily reduced the leachable chloride content at least when the initial leachable chloride surface coverage was calculated to be > 0.5 monolayer (ML). Variations between samples are attributed to differences in surface area as well as production route and period of interim storage in air or humidified atmospheres. The data are consistent with surface species and reactions proposed in the literature for HCl adsorption on to TiO2. This indicates that it is interactions between hydrogen chloride/chloride and water/hydroxyl species on the PuO2 surface that are key to understanding the behaviour of these materials when heated in a furnace. These data will inform the design of a future thermal stabilisation process for chloride-contaminated PuO2.

Sutherland-Harper, Sophie↗