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At least 973 records · Page 54
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Chromosome aberrations among atomic-bomb survivors exposed in utero: updated analysis accounting for revised radiation doses and smoking

A previous study of peripheral blood lymphocyte translocations around age 40 among atomic-bomb survivors exposed in utero revealed no overall association with radiation dose—despite a clear association between translocations and dose among their mothers—but the data suggested an increase at doses below 100 mGy with a definite peak. That analysis of the in utero-exposed survivors did not adjust for their subsequent smoking behavior, an established cause of chromosomal aberrations, or their subsequent exposures to medical irradiation, a potential mediator. In addition, atomic-bomb survivor radiation dose estimates have subsequently been updated and refined. We therefore re-estimated the dose response using the latest DS02R1 dose estimates and adjusting for smoking as well as for city and proximal–distal location at the time of exposure to the atomic bomb. Sex of the survivor, mother’s age around the time of conception, and approximate trimester of gestation at the time of exposure were also considered as explanatory variables and modifiers. Precision of the estimated dose response was slightly lower due to greater variability near zero in the updated dose estimates, but there was little change in evidence of a low-dose increase and still no suggestion of an overall increase across the entire dose range. Adjustment for smoking behavior led to a decline in background number of translocations (the dose–response intercept), but smoking did not interact with dose overall (across the entire dose range). Adjustment for medical irradiation did not alter the association between dose and translocation frequency. Sex, mother’s age, and trimester were not associated with number of translocations, nor did they interact with dose overall. Interactions with dose in the low-dose range could not be evaluated because of numerical instability.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2017

Accelerated thermal aging of harvested hypalon jacket for remaining useful life determination and diagnosis - 210

For nuclear power plants (NPPs) considering second license renewal for their operation beyond 60 years, knowledge of long-term operation, condition monitoring, and viability for the reactor components including reactor pressure vessel, concrete structures, and cable systems is essential. Such knowledge will provide NPPs with a game plan to predict performance and to estimate costs that are associated with monitoring or replacement programs for the affected systems. For cable systems that encompass a wide variety of materials, manufacturers, and in-plant location, accelerated aging of harvested cable jacket and insulation can provide insight as to remaining useful life and methods for monitoring. Accelerated thermal aging in air at temperatures between 80 deg. C and 120 deg. C was carried out on a multi-conductor control rod cable that had been inservice for over 30 years and was made by Boston Insulated Wire with Hypalon{sup TM} cable jacket and ethylene-propylene rubber insulation. From elongation at break (EAB) measurements and supporting Arrhenius analysis of the jacket material, an activation energy of 97.84 kJ/mol was estimated and the time to degradation, as represented by 50% EAB at the expected maximum operating temperature of 45 deg. C, was estimated to be 80 years. These values were slightly below previous measurements on similar BIW Hypalon cable jacket and could either be attributed to inservice degradation or variations in material properties from process variations. In addition, results from indenter modulus measurements and Fourier transform infrared spectroscopy suggest possible markers that could be beneficial to monitor cable conditions. (authors)

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2015

Size-segregated emissions and metal content of vehicle-emitted particles as a function of mileage: Implications to population exposure

The study aims at investigating the characteristics (size distribution, active surface and metal content) of particles emitted by cars as a function of mileage using a novel methodology for characterizing particulate emissions captured by Exhaust Gas Suspension (EGS). EGS was obtained by passing the exhaust gases through a container of deionized water. EGS analysis was performed using laser granulometry, electron scanning microscopy, and high resolution mass spectrometry. Implications of the differences in key features of the emitted particles on population exposure were investigated using numerical simulation for estimating size-segregated PM deposition across human respiratory tract (HRT). It was found that vehicle mileage, age and the respective emissions class have almost no effect on the size distribution of the exhaust gas particulate released into the environment; about half of the examined vehicles with low mileage were found to release particles of aerodynamic diameter above 10 μm. The exhaust gas particulate detected in the EGS of all cars can be classified into three major size classes: (1) 0.1–5 µm – soot and ash particles, metals (Au, Pt, Pd, Ir); (2) 10–30 µm – metal (Cr, Fe, Cu, Zr, Ni) and ash particles; (3) 400–1,000 µm – metal (Fe, Cr, Pb) and ash particles. Newer vehicles with low mileage are substantial sources of soot and metal particles with median diameter of 200 nm with a higher surface area (up to 89,871.16 cm{sup 2}/cm{sup 3}). These tend to deposit in the lower part of the human respiratory tract. - Highlights: • Car mileage has virtually no effect on the size of the solid particles released. • Newer diesel vehicles emit particles of lower aerodynamic diameter. • Particle active surface emitted by newer vehicles is on average 3 times higher. • Real-life emissions were translated into actual internal PM exposure.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Effect of Solar Radiation on the Optical Properties and Molecular Composition of Laboratory Proxies of Atmospheric Brown Carbon

Sources, optical properties, and chemical composition of atmospheric brown carbon (BrC) aerosol are uncertain, making it challenging to estimate its contribution to radiative forcing. Furthermore, optical properties of BrC may change significantly during its atmospheric aging. We examined the effect of solar photolysis on the molecular composition, mass absorption coefficient, and fluorescence of secondary organic aerosol prepared by high-NO x photooxidation of naphthalene (NAP SOA). The aqueous solutions of NAP SOA was observed to photobleach with an effective half-time of ~15 hours (with sun in its zenith) for the loss of the near-UV (300 -400 nm) absorbance. The molecular composition of NAP SOA was significantly modified by photolysis, with the average SOA formula changing from C 14.1 H 14.5 O 5.1 N 0.08 to C 11.8 H 14.9 O 4.5 N 0.02 after 4 hours of irradiation. The average O/C ratio did not change significantly, however, suggesting that it is not a good metric for assessing the extent of photolysis-driven aging in NAP SOA (and in BrC in general). In contrast to NAP SOA, the photolysis of BrC material produced by aqueous reaction of limonene+O 3 SOA (LIM/O 3 SOA) with ammonium sulfate was much faster, but it did not result in a significant change in the molecular level composition. The characteristic absorbance of the aged LIM/O 3 SOA in the 450-600 nm range decayed with an effective half-time of <0.5 hour. This result emphasizes the highly variable and dynamic nature of different types of atmospheric BrC.

Environmental Molecular Sciences Laboratory↗
DOE OSTI2022

Stellar Populations in type Ia supernova host galaxies at intermediate-high redshift: Star formation and metallicity enrichment histories

ABSTRACT We present a summary of our project that studies galaxies hosting type Ia supernova (SN Ia) at different redshifts. We present Gran Telescopio de Canarias (GTC) optical spectroscopy of six SN Ia host galaxies at redshift z ∼ 0.4–0.5. They are joined to a set of SN Ia host galaxies at intermediate-high redshift, which include galaxies from surveys SDSS and COSMOS. The final sample, after a selection of galaxy spectra in terms of signal-to-noise and other characteristics, consists of 680 galaxies with redshift in the range 0.04 < z < 1. We perform an inverse stellar population synthesis with the code fado to estimate the star formation and enrichment histories of this set of galaxies, simultaneously obtaining their mean stellar age and metallicity and stellar mass. After analysing the correlations among these characteristics, we look for possible dependencies of the Hubble diagram residuals and supernova features (luminosity, colour and strength parameter) on these stellar parameters. We find that the Hubble residuals show a clear dependence on the stellar metallicity weighted by mass with a slope of −0.061 mag dex−1, when represented in logarithmic scale, log 〈ZM/Z⊙〉. This result supports our previous findings obtained from gas oxygen abundances for local and SDSS-survey galaxies. Comparing with other works from the literature that also use the stellar metallicity, we find a similar value, but with more precision and a better significance (2.08 versus ∼ 1.1), due to the higher number of objects and wider range of redshift of our sample.

Millán-Irigoyen, I. (ORCID:0000000341155140)↗
DOE OSTI2023

Male Runners With Lower Energy Availability Have Impaired Skeletal Integrity Compared to Nonathletes

Abstract Context Female athletes, particularly runners, with insufficient caloric intake for their energy expenditure [low energy availability (EA) or relative energy deficiency] are at risk for impaired skeletal integrity. Data are lacking in male runners. Objective To determine whether male runners at risk for energy deficit have impaired bone mineral density (BMD), microarchitecture, and estimated strength. Design Cross-sectional. Setting Clinical research center. Participants 39 men (20 runners, 19 controls), ages 16–30 years. Main Outcome Measures Areal BMD (dual-energy x-ray absorptiometry); tibia and radius volumetric BMD and microarchitecture (high-resolution peripheral quantitative computed tomography); failure load (microfinite element analysis); serum testosterone, estradiol, leptin; energy availability. Results Mean age (24.5 ± 3.8 y), lean mass, testosterone, and estradiol levels were similar; body mass index, percent fat mass, leptin, and lumbar spine BMD Z-score (−1.4 ± 0.8 vs −0.8 ± 0.8) lower (P < .05); and calcium intake and running mileage higher (P ≤ .01) in runners vs controls. Runners with EA <median had lower lumbar spine (−1.5 ± 0.7, P = .028), while runners with EA ≥median had higher hip (0.3 ± 0.7 vs −0.4 ± 0.5, P = .002), BMD Z-scores vs controls. After adjusting for calcium intake and running mileage, runners with EA <median had lower mean tibial total and trabecular volumetric BMD, trabecular bone volume fraction, cortical porosity, and apparent modulus vs controls (P < .05). Appendicular lean mass and serum estradiol (R ≥ 0.45, P ≤ .046), but not testosterone, were positively associated with tibial failure load among runners. Conclusions Despite weight-bearing activity, skeletal integrity is impaired in male runners with lower caloric intake relative to exercise energy expenditure, which may increase bone stress injury risk. Lower estradiol and lean mass are associated with lower tibial strength in runners.

Haines, Melanie S. (ORCID:0000000310024754)↗
DOE OSTI2020

Science and Technology of High Performance Ferritic (HiperFer) Stainless Steels

Future, flexible thermal energy conversion systems require new, demand-optimized high-performance materials. The High performance Ferritic (HiperFer) stainless steels, under development at the Institute of Microstructure and Properties of Materials (IEK-2) at Forschungszentrum Jülich GmbH in Germany, provide a balanced combination of fatigue, creep and corrosion resistance at reasonable price. This paper outlines the scientific background of alloy performance development, which resulted in an age-hardening ferritic, stainless steel grade. Furthermore, technological properties are addressed and the potential concerning application is estimated by benchmarking versus conventional state of the art materials.

36 MATERIALS SCIENCE↗
NASA NTRS1978

Quantitative mapping of particulate iron in an ocean dump using remotely sensed data

A remote sensing experiment was conducted at the industrial acid waste ocean dump site located approximately 38 n mi SE of Cape Henlopen, Delaware, to see if there was a relationship between aircraft remotely sensed spectral signatures and the iron concentration measured in the plume. Results are presented which show that aircraft remotely sensed spectral data can be used to quantify and map an acid waste dump in terms of its particulate iron concentration. A single variable equation using the ratio of band 2 (440-490 nm) radiance to band 4 (540-580 nm) radiance was used to quantify the acid plume and the surrounding water. The acid waste varied in age from freshly dumped to 3 1/2 hours old. Particulate iron concentrations in the acid waste were estimated to range up to 1.1 mg/liter at the 0.46 meter depth. A classification technique was developed to remove sunglitter-affected pixels from the data set.

Ohlhorst, C. W.↗
NASA NTRS1991

Recent star formation in the interacting galaxy system NGC 520

New optical spectroscopy, near-infrared spectroscopy, and mid-infrared imaging of the interacting system NGC 520 are presented. The data show that the heavily obscured primary nucleus has a current star-forming rate about 35 times the typical rate for a late-type galaxy nucleus, which may account for most of the large far-infrared luminosity of NGC 520. The secondary nucleus has little current star formation but has recently undergone a mild starburst. Optical colors and absorption line equivalent widths suggest that the extranuclear regions in both galaxies have experienced enhanced star formation roughly at the same time as the secondary nucleus, though at a lesser intensity. The extent of the extranuclear burst is large; at least half of the projected surface area of the two disks took part to varying degrees in the episode. Determining the exact age and strength of the recent star-formation episode in NGC 520 is uncertain. The best estimate for the initiation time of about few x 10 exp 8 yrs ago is consistent with the system-wide starburst being caused by the galaxy collision.

Stanford, S. A.↗
NASA NTRS1997

Lateral Shock of the R Aquarii Jet

The R Aqr jet was observed with the VLA B-configuration at two epochs separated by approximately 13.2 yr. Comparison of the resulting 6 cm continuum images show that the radio jet has undergone a lateral counterclockwise rotation of approximately 6 deg-12 deg on the plane of the sky. The model of jet parcels on independent trajectories is difficult to reconcile with these observations and leads us to consider a path-oriented jet (i.e., younger parcels follow the same path as older parcels). Comparison of the most recent radio image with a nearly contemporaneous HST/FOC ultraviolet image at approximately 2330 Angstroms suggests that the ultraviolet emission lies along the leading side of the rotating radio jet. In conjunction with a proper motion analysis of the jet material that yields empirical space-velocity and resulting acceleration-magnitude relationships as a function of distance from the central source, we evaluate the observational results in terms of a schematic model in which the jet emission consists of plane-parallel isothermal shocks along the leading edge of rotation. In such a radiating shock, the ultraviolet-emitting region is consistent with the adiabatic region in the form of a high-temperature, low-density sheath that surrounds the cooled postshock radio-emitting region. Within the context of the schematic model, we obtain the temperatures, densities, and pressures within the preshock, adiabatic, and postshock regions as a function of distance from the central source; the physical parameters so derived compare favorably to previously published estimates. We obtain a total jet mass of 3.1 x 10(exp -5) solar mass and an age of approximately 115 yr. We evaluate the model in the context of its density-boundary condition, its applicability to an episodic or quasi-continuous jet, and angular momentum considerations.

Hollis, J. M.↗
DOE OSTI2018

Aerial Lidar and Geomorphic Change Detection Software- Tools for Monitoring Canyon Sediments at LANL - 18668

The Los Alamos National Laboratory Environmental Remediation program has conducted extensive geomorphic surveys of sediment deposits in the canyon bottoms within and surrounding the facility. The goal of the geomorphic surveys was to provide basic information needed to characterize chemical inventories of the sediments downstream of historical release sites. Sediment units were mapped based on depositional setting and age. Representative characterization samples were collected for each unit and submitted for chemical analysis. Chemical inventories were estimated by calculating the total volume of each depositional unit and multiplying by average chemical concentration. This method of characterization provides a spatial distribution of chemical data based on fluvial processes. In general, for the canyon bottom sediments, the higher concentrations of industrial chemicals were associated with fine-grained floodplain deposits closest to the source. Since initial characterization, many of the reaches have undergone changes in response to post-wildfire floods and severe rain events. These events impacted the channel and floodplain deposits. Much of the elevated concentrations are confined to the over-bank deposits distal from the primary channel. In order to ensure that the sediment units containing elevated chemical concentrations are stable, repeat aerial light detection and ranging (LiDAR) surveys are conducted and changes are assessed using the Geomorphic Change Detection (GCD) plug-in for ArcGIS. These tools provide high confidence uncertainty estimates and extensive areal coverage. This is a valuable method for long-term monitoring of surface sediments with low-level but widespread contaminant distributions. All of the monitored canyon bottom reaches pass risk assessment and present technically infeasible sediment removal options. Following the 2014 monsoon season, aerial LiDAR data has been collected annually and the resulting digital elevation models (DEMs) processed using the GCD method. Changes are identified using GCD and are verified by field walk downs. If erosion is identified in areas which are vulnerable to mobilizing contaminated sediment, enhanced controls can be installed to stabilize banks or other areas with high erosion potential. Annual sediment monitoring samples are collected where there is evidence for flow and deposition within the past year. Since 2014, no severe floods have been catalogued using the LiDAR surveys and GCD software. The recent rainfall/runoff events have not caused major changes to the canyon bottom channels and floodplains. Geomorphic processes identified in the monitoring results include channel aggradation and incision that over the course of a monsoon season results in minor changes to the system. Other active processes contributing to observed changes are minor slides, flows, slumps, and falls of unconsolidated sediment on steep bedrock or soil surfaces. A comprehensive baseline has been established by geomorphic mapping and characterization sampling. Periodic monitoring consists of LiDAR surveys and GCD analysis which offers an effective and defensible methodology for documenting stability of surface sediments. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2022

A GALAH view of the chemical homogeneity and ages of stellar strings identified in Gaia

ABSTRACT The advent of Gaia has led to the discovery of nearly 300 elongated stellar associations (called ‘strings’) spanning hundreds of parsecs in length and mere tens of parsecs in width. These newfound populations present an excellent laboratory for studying the assembly process of the Milky Way thin disc. In this work, we use data from GALAH DR3 to investigate the chemical distributions and ages of 18 newfound stellar populations, 10 of which are strings and 8 of which are compact in morphology. We estimate the intrinsic abundance dispersions in [X/H] of each population and compare them with those of both their local fields and the open cluster (OC) M 67. We find that all but one of these groups are more chemically homogeneous than their local fields. Furthermore, half of the strings, namely Theias 139, 169, 216, 303, and 309, have intrinsic [X/H] dispersions that range between 0.01 and 0.07 dex in most elements, equivalent to those of many OCs. These results provide important new observational constraints on star formation and the chemical homogeneity of the local interstellar medium (ISM). We investigate each population’s Li and chemical clock abundances (e.g. [Sc/Ba], [Ca/Ba], [Ti/Ba], and [Mg/Y]) and find that the ages suggested by chemistry generally support the isochronal ages in all but six structures. This work highlights the unique advantages that chemistry holds in the study of kinematically related stellar groups.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2022

A GALAH View of the Chemical Homogeneity and Ages of Stellar Strings Identified in Gaia

The advent of Gaia has led to the discovery of nearly 300 elongated stellar associations (called ‘strings’) spanning hundreds of parsecs in length and mere tens of parsecs in width. These newfound populations present an excellent laboratory for studying the assembly process of the Milky Way thin disc. In this work, we use data from GALAH DR3 to investigate the chemical distributions and ages of 18 newfound stellar populations, 10 of which are strings and 8 of which are compact in morphology. We estimate the intrinsic abundance dispersions in [X/H] of each population and compare them with those of both their local fields and the open cluster (OC) M 67. We find that all but one of these groups are more chemically homogeneous than their local fields. Furthermore, half of the strings, namely Theias 139, 169, 216, 303, and 309, have intrinsic [X/H] dispersions that range between 0.01 and 0.07 dex in most elements, equivalent to those of many OCs. These results provide important new observational constraints on star formation and the chemical homogeneity of the local interstellar medium (ISM). We investigate each population’s Li and chemical clock abundances(e.g. [Sc/Ba], [Ca/Ba], [Ti/Ba], and [Mg/Y]) and find that the ages suggested by chemistry generally support the isochronal ages in all but six structures. This work highlights the unique advantages that chemistry holds in the study of kinematically related stellar groups.

Stars: abundances↗
DOE OSTI2025

Validating Greater Sage-Grouse Individual-based Model (IBM) Tool (Final Report)

The project focused on validating the previously developed Greater Sage-Grouse Individual-based Model (GrSG IBM; LaGory et al. 2012, 2021). The objective was to transform this predictive, spatially and temporally explicit model into a portable resource to assist siting/resource managers in proactively assessing the cumulative impacts of wind energy development on the greater sage-grouse. Utilizing a bottom-up, individual-based approach, the GrSG IBM accounts for landscape context and species behavior, aiming to reduce uncertainty in estimating development impacts and support ecologically mindful land-based wind energy development. The validation effort covered approximately 6,540 km 2 near the Seven Mile Hill Wind Project in Wyoming. The GrSG IBM tool, built on the NetLogo platform (Tisue and Wilensky 2004), was executed over a 50-year period, with the analysis focusing on years following a 10-year initialization phase. Key results demonstrated the tool’s biological soundness across five key biological metrics: non-chick age class distribution (older than 10 weeks), adult sex ratio, life expectancy, population size, and overall population growth. For instance, the tool estimated that 58.6% of the non-chick population was reproductively immature, while the reference ranges from 51.4% to 57.8% (Patterson 1952, Rogers 1964). Experts confirmed the tool’s estimate was within a reasonable range for the species. The tool estimated average life expectancy of 1.43 years, while the reference ranges from 0.9 years to 1.1 years (Ammann 1957, Hamerstrom 1949). Experts also supported the model’s life-expectancy estimate as ecologically sound for the species in the study area. In terms of population change, the model estimated an annual shift between a 0.6% decline and a 1.0% increase over 50 years. While the reference suggests 2.9% annual decline in range-wide populations (Cortes et al. 2023), that includes many at-risk populations in South Dakota and Washington, for example. Our study area—in the northeastern part of Carbon County and western-edge of Albany County, Wyoming—is one of the remaining greater sage-grouse habitats supporting some of the most stable populations. Experts confirmed that the range of the annual population change spanning from a 0.6% decline to a 1.0% increase estimated by the tool was reasonable for our study area for this reason and confirmed that aligned with population estimates from existing studies on the greater sage-grouse and wind energy development in the study area (LeBeau et al. 2017a, Smith et al. 2024). Furthermore, the project showed that temporally explicit biological metrics generated by the GrSG IBM tool can complement the USGS’ Prioritizing Restoration of Sagebrush Ecosystems Tool (PReSET; Duchardt et al. 2021) by incorporating habitat restoration strategies into seasonal habitat suitability models to visualize population responses over time.

17 WIND ENERGY↗
DOE OSTI2015

Status Report - Softwood Fiberboard Properties And Degradation Rates For Storage Of The 9975 Shipping Package In KAC

Thermal, mechanical and physical properties have been measured on softwood fiberboard samples following accelerated aging for up to approximately 7 years. The aging environments have included elevated temperature < 250 ºF (the maximum allowed service temperature for fiberboard in 9975 packages) and elevated humidity. The results from this testing have been analyzed, and preliminary aging models fit to the data. Correlations relating several properties (thermal conductivity, energy absorption, weight, dimensions and density) to their rate of change in potential storage environments have been developed. Combined with acceptance criteria and an estimate of the actual conditions the fiberboard experiences in KAC, these models allow development of service life predictions.

42 ENGINEERING↗
DOE OSTI2018

Pregnancy exposure to wind turbine noise and adverse birth outcomes: a nationwide cohort study

Highlights: • We identified all Danes exposed to wind turbine noise (WTN) from 1982 to 2013. • We then identified all live born singletons from mothers in this population. • We investigated preterm birth, low birth weight and small for gestational age. • We found no associations between WTN and the adverse birth outcomes. • Few women had high levels of WTN and independent replication is called for. Noise from wind turbines (WTs) is reported as more annoying than traffic noise at similar levels, raising concerns as to whether WT noise (WTN) may negatively affect health, as reported for traffic noise. We aimed to investigate whether residential WTN is associated with adverse birth outcomes. Based on national registries, we identified all Danish dwellings situated within ≤ 20 wt heights radius and a random selection of 25% of dwellings situated within 20–40 wt heights radius of a WT. We identified 135,795 pregnant women living in the dwellings from 1982 to 2013, and collected information on gestational age and birth weight from a national birth registry. Using data on WT type and simulated hourly wind at each WT, we estimated hourly outdoor and low frequency (LF) indoor WTN at the dwellings of the pregnant women and aggregated as mean nighttime WTN during pregnancy. We used logistic regression with adjustment for individual and area-level covariates for the analyses. We did not find evidence suggesting that mean pregnancy or trimester-specific exposure to outdoor or indoor LF WTN were associated with any of the three adverse birth outcomes investigated: preterm birth (n = 13,003), term small for gestational age (n = 12,220) or term low birth weight (n = 1127). However, the number of cases in the highest exposure categories of ≥ 42 dB outdoor WTN or ≥ 15 dB indoor LF WTN were low for all outcomes (n between 0 and 31). The present study does not support an association between nighttime WTN and adverse birth outcomes. However, there were few cases in the high exposure groups and the results call for reproduction.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

Cardiorespiratory fitness and health‐related quality of life in adolescents: A longitudinal analysis from the LabMed Physical Activity Study

Abstract Objective The purpose of this study was to examine the longitudinal associations between cardiorespiratory fitness and health‐related quality of life (HRQoL) in a sample of adolescents, and to determine whether changes in cardiorespiratory fitness were associated with HRQoL over a 2‐year follow‐up. Methods This is a longitudinal analysis with 571 Portuguese adolescents (274 boys and 297 girls) aged 12‐18 years. HRQoL was measured with the Kidscreen‐10 questionnaire; the 20 m shuttle‐run was used to estimate cardiorespiratory fitness; socioeconomic status was assessed with the Family Affluence Scale; and pubertal stage was assessed with Tanner stages. Linear regression and analysis of covariance ( ancova s) were used to examine the associations between cardiorespiratory fitness and HRQoL. Results HRQoL decreased over a 2‐year period both in boys and girls ( P < .05). Moreover, girls at baseline and at follow‐up reported significantly lower HRQoL values than boys (between subjects P < .001). After adjustments for potential confounders, regression analyses showed significant cross‐sectional associations between cardiorespiratory fitness and HRQoL both at baseline ( B = 0.095; P = .023) and at follow‐up (B = 0.090; P = .012). ancova showed that adolescents whose cardiorespiratory fitness decreased over time exhibited lower scores of HRQoL at follow‐up, compared to those with persistent high cardiorespiratory fitness; this held after adjustments for age, sex, socioeconomic status, and pubertal stage. Conclusions Changes in cardiorespiratory fitness during adolescence were associated with HRQoL over a 2‐year period. This study suggests that improving cardiorespiratory fitness could be an important strategy in improving the HRQoL of adolescents.

Evaristo, Olga S.↗
DOE OSTI2017

ACCELERATED THERMAL AGING OF HARVESTED HYPALON JACKET FOR REMAINING USEFUL LIFE DETERMINATION AND DIAGNOSIS

For nuclear power plants (NPPs) that are considering second license renewal for their operation beyond 60 years, knowledge of long-term operation, condition monitoring, and viability for the reactor components including reactor pressure vessel, concrete structures, and cable systems is essential. Such knowledge will provide NPPs with a game plan to predict performance and to estimate costs that are associated with monitoring or replacement programs for the affected systems. For cable systems that encompass a wide variety of materials, manufacturers, and in-plant location, accelerated aging of harvested cable jacket and insulation can provide insight as to remaining useful life and methods for monitoring. Accelerated thermal aging in air at temperatures between 80°C and 120°C was carried out on a multi-conductor control rod cable that had been in-service for over 30 years and was made by Boston Insulated Wire with Hypalon cable jacket and ethylene-propylene rubber insulation. From elongation at break (EAB) measurements and supporting Arrhenius analysis of the jacket material, an activation energy of 97.84 kJ/mol was estimated and the time to degradation, as represented by 50% EAB at the expected maximum operating temperature of 45°C, was estimated as consistent with 80 years. These values were slightly below previous measurements and could either be attributed to in-service degradation or variations in material properties from a given manufacturer. In addition, results from indenter modulus measurements and Fourier transform infrared spectroscopy suggest possible markers that could be beneficial to monitor cable conditions.

Glass III, Samuel W.↗