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Background Vitamin A (VA) estimated average requirements (EARs) for women and children are extrapolated from rats and adult males. The retinol isotope dilution (RID) test can sensitively characterize VA status and intake requirements. Objectives These studies evaluated current EARs for children 4–8 y and women 19–30 y old. Methods Zambian children (n  = 133, ages 5–7 y), US women (n  = 51, ages 19–27 y), and Indonesian women (n  = 29, ages 19–30 y) were provided diets or supplements containing 30%–155% of VA EARs for 42–90 d. RID was performed before and after the intervention to quantify changes in total body VA stores (TBSs) and total liver VA reserves (TLRs). Linear regression was performed between VA intake and change in TBSs or TLRs. Results Baseline mean ± SD TLRs were hypervitaminotic in Zambian children (1.13 ± 0.41 μmol VA/g liver), optimal in US women (0.46 ± 0.32 μmol/g VA/g liver), and deficient to marginal in Indonesian women (0.10 ± 0.08 μmol VA/g liver). VA intakes, resulting in no change in TBSs or TLRs, were 185 (95% CI: 18, 288) or 257 (95% CI: 124, 411) and 285 or 330 (CIs undefined) μg retinol activity equivalents (RAE)/d in the Zambian and US trials, respectively, but inconclusive in Indonesian women. The regression was not significant in either group of women. Conclusions Point estimates of VA intakes to maintain stores were below the current EARs of 275 (children) and 500 (women) μg RAE/d despite the TLRs being higher than the EARs were formulated to maintain (i.e. 0.07 μmol VA/g liver). Interventions based on these EARs may need to be scaled back. Lack of change in VA stores in women taking lower doses may result from physiological adaptation resulting in lower VA utilization. Longer, larger, and controlled studies are needed to accurately define EARs for VA. These trials were registered at Clinicaltrials.gov as NCT04123210 and NCT01814891. [ABSTRACT FROM AUTHOR]

Background: The carbon isotope ratio (CIR) is a proposed biomarker for added sugar (AS) intake in the United States; however, because the CIR is also associated with meat intake in most populations the need for specificity remains. The CIR of amino acids (AAs) has the potential to differentiate sugars from meat intakes, because essential AAs must derive from dietary protein whereas certain nonessential AAs can be synthesized from sugars.Objectives: We tested whether serum CIR-AAs in combination with participant characteristics could meet a prespecified biomarker criterion for AS intake in the Nutrition and Physical Activity Assessment Study Feeding Study (NPAAS-FS) of the Women's Health Initiative, a population in which the whole-serum CIR was not associated with AS intake.Methods: Postmenopausal women (n = 145) from Seattle, WA, were provided with individualized diets that approximated their habitual food intakes for 2 wk. Dietary intakes from consumed foods were characterized over the feeding period using the Nutrition Data System for Research. The CIR of 7 AAs-Ala, Gly, Val, Leu, Ile, Pro, and Phe-were measured in fasting serum collected at the end of the 2-wk feeding period, using gas chromatography-combustion isotope ratio mass spectrometry. Biomarker models were evaluated using regression R2 ≥ 0.36 as a major biomarker criterion, based on the benchmark R2 values of well-established recovery biomarkers in the NPAAS-FS.Results: AS intake was associated with CIR-Ala (ρ = 0.32; P < 0.0001). A model of AS intake based on CIR-Ala, CIR-Gly, CIR-Ile, smoking, leisure physical activity, and body weight met the biomarker criterion (R2 = 0.37). Biomarker-estimated AS intake was not associated with meat or animal protein intake.Conclusions: Results support serum CIR-AAs in combination with participant characteristics as potential biomarkers of AS intake in US populations, including those with low AS intake.The Women's Health Initiative is registered at clinicaltrials.gov (NCT00000611). [ABSTRACT FROM AUTHOR]

Regulatory authorities like the U.S. Food and Drug Administration (FDA) have set strict specification levels for N-nitrosamines in finished drug products. Nitrite is a potential precursor for the formation of probable carcinogenic N-nitrosamines when secondary or tertiary amines are also present in the active pharmaceutical ingredient (API) synthesis or drug formulation process. An accurate and sensitive determination of nitrite will be useful when a drug product manufacturer chooses to investigate the reaction kinetics between nitrite and amines or to select appropriate excipients for its drug formulation. Pharmaceutical excipient manufacturers may also need an accurate nitrite measurement to investigate the nitrite content in their excipients. This study details the development and validation of an ion chromatography mass spectrometry (IC-MS) method for trace nitrite determination in microcrystalline cellulose materials, one of the important pharmaceutical excipients used in many drug formulations. MS operated under selected ion monitoring mode was used to solve the commonly encountered interference issue with conductivity detection, and nitrite isotope internal standard was employed to address the ion suppression issue with MS detection. The installation of an after-column "jumper" to flush water with an auxiliary pump through the MS when it is not used for data collection avoided sensitivity loss due to trace salt accumulation in the ion source. Validation of the optimized method was satisfactory, with linearity of nitrite in the concentration range of 0.02-7.50 ppm (µg/g) having a regression coefficient of > 0.999, precision of RSD < 9.5% at 0.03 ppm and RSD < 3.4% at 0.4 ppm and recovery of 92.0-103.0%. The limit of detection and limit of quantitation were 0.005 and 0.016 ppm, respectively., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

To understand the impact reduced mercury (Hg) loading and invasive species have had on methylmercury bioaccumulation in predator fish of Lake Michigan, we reconstructed bioaccumulation trends from a fish archive (1978 to 2012). By measuring fish Hg stable isotope ratios, we related temporal changes in Hg concentrations to varying Hg sources. Additionally, dietary tracers were necessary to identify food web influences. Through combined Hg, C, and N stable isotopic analyses, we were able to differentiate between a shift in Hg sources to fish and periods when energetic transitions (from dreissenid mussels) led to the assimilation of contrasting Hg pools (2000 to present). In the late 1980s, lake trout δ202Hg increased (0.4‰) from regulatory reductions in regional Hg emissions. After 2000, C and N isotopes ratios revealed altered food web pathways, resulting in a benthic energetic shift and changes to Hg bioaccumulation. Continued increases in δ202Hg indicate fish are responding to several United States mercury emission mitigation strategies that were initiated circa 1990 and continued through the 2011 promulgation of theMercury and Air Toxics Standards rule. Unlike archives of sediments, this fish archive tracks Hg sources susceptible to bioaccumulation in Great Lakes fisheries. Analysis reveals that trends in fish Hg concentrations can be substantially affected by shifts in trophic structure and dietary preferences initiated by invasive species in the Great Lakes. This does not diminish the benefits of declining emissions over this period, as fish Hg concentrations would have been higher without these actions. [ABSTRACT FROM AUTHOR]

Serpentinites and serpentinized mantle peridotites with various tectonic origins occur in the Franciscan Complex of the Northern California Cordillera, USA. Boron isotopes of serpentinites differentiate with fluid-mediated processes, and have great potential for key geologic markers in convergent margins. To understand boron isotope behavior within the Franciscan subduction zone system, we apply a newly developed ablation volume correction (AVC) method for in-situ isotope/elemental analyses using a laser-ablation multiple collector inductively-coupled-plasma mass spectrometry (LA-MC-ICPMS) on seventeen different Franciscan serpentinites (sensu lato) collected from eight separate areas. Boron abundances and isotope compositions of the studied serpentinites show large variations B = 1.6–239 μg·g−1, δ11B = −12.0 to +24.4‰, which allow to discriminate the serpentinites into two groups: (1) a lighter δ11B of −12.0 to +8.8‰ with a lesser B < ~56 μg·g−1 and (2) a heavier δ11B of +7.2 to +24.4% with a greater B ~34–239 μg·g−1. These groups lithologically correspond to the presence or absence of associated blueschist-facies metamorphic rocks, respectively. The blueschist-bearing and/or blueschist-associated serpentinites might have been affected by a deep forearc slab fluids in the depth of > ~2 GPa. Preferential partitioning of 11B into fluids released from the subducted slab at shallow leaves lighter δ11B in the slab resulting in lighter δ11B in the deep slab fluids. In contrast, the blueschist-absent serpentinites with heavier δ11B may have formed at a shallow environment where shallow slab or hydrothermal fluids with heavier 11B were present. Lesser versus greater amounts of B in the deep versus shallow serpentinites are also consistent with the dehydration profile of B from a slab. Our results show the versatility of boron isotopes and composition for identification of the origin of serpentinite in Pacific-type orogenic belts. • B isotope compositions of Franciscan serpentinites (17 samples from 8 localities) were determined by LA-MC-ICPMS. • The B isotope composition discriminates the serpentinites into two groups. • Serpentinites associated with blueschists are characterized by low δ11B (−12 to +8.8‰). • Serpentinites without blueschists are characterized by high δ11B (+7.2 to +24.4‰). • The results show the versatility of B isotopes for identification of the origin of serpentinite. [ABSTRACT FROM AUTHOR]

The article discusses the factors that led to the weakening of U.S. export controls on bomb-grade uranium. The Energy Policy Act of 2005 which includes an amendment that eased off restrictions on the export of highly enriched uranium was forced into law by foreign producers of medical isotopes, their U.S.-based lobbyists, sectors of the U.S. medical community and the compliant lawmakers. The primary agitator for this was Canada's Nordion, the world's largest producer of medical isotopes and the main supplier to the U.S.

Purpose: While Ir-192 remains the mainstay isotope for gynecologic high-dose-rate (HDR) brachytherapy in the U.S., Co-60 is used abroad. Co-60 has a longer half-life than Ir-192, which may lead to long-term cost savings; however, its higher energy requires greater shielding. This study analyzes Co-60 acceptability based on a one-time expense of additional shielding and reports the financial experience of Co-60 in Peru’s National Cancer Institute, which uses both isotopes. Material and methods: A nationwide survey was undertaken assessing physician knowledge of Co-60 and willingness-to-pay (WTP) for additional shielding, assuming a source more cost-effective than Ir-192 was available. With 440 respondents, 280 clinicians were decision-makers and provided WTPs, with results previously reported. After completing a shielding report, we estimated costs for shielding expansion, noting acceptability to decision makers’ WTP. Using activity-based costing, we note the Peruvian fiscal experience. Results: Shielding estimates ranged from $173,000 to $418,000. The percentage of respondents accepting high-density modular or lead shielding (for union and non-union settings) were 17.5%, 11.4%, 3.9%, and 3.2%, respectively. Shielding acceptance was associated with greater number of radiation oncologists in a respondent’s department but not time in practice or the American Brachytherapy Society membership. Peru’s experience noted cost savings with Co-60 of $52,400 annually. Conclusions: By comparing the cost of additional shielding for a sample institution’s HDR suite with radiation oncologists’ WTP, this multi-institutional collaboration noted < 20% of clinicians would accept additional shielding. Despite low acceptability in the US, Co-60 demonstrates cost-favorability in Peru and may similarly in other locations. [ABSTRACT FROM AUTHOR]

Background: Retinol isotope dilution (RID) indirectly estimates vitamin A (VA) status. Multicompartment modeling of RID data is used to refine study designs and equations to calculate VA stores. Previous studies suggest that VA in slowly turning over pools is not traced if follow-up is not long enough; however, shorter RID studies are being investigated. Few long-term models have been published.Objective: We determined the effect of time on mathematical models of VA kinetics, model parameters, and outcomes.Methods: In this longitudinal study, women (mean ± SD age: 22 ± 3 y; n = 7) were given 2.0 µmol [14,15]-13C2-retinyl acetate. Blood samples were staggered from 4 h to 152 d; the fraction of dose in serum was modeled with compartmental models. Four model-time categories were created: full models that used all data (median: 137 d; range 97-152 d) and truncated shorter studies of 14, 27, and 52 d (range: 42-62 d). Outcomes included number of compartments to adequately model serum data, kinetic parameters, total traced VA mass, and time-to-dose equilibration. To gain insight into longer follow-up, an additional participant was given 17.5 µmol 13C4-VA, and data were modeled as long as enrichment was above baseline (5 y).Results: Longer follow-up times affected kinetic parameters and outcomes. Compared with the 14-d models, long-term full models required an additional compartment for adequate fit (14.3% compared with 100%; P = 0.0056) and had longer [median (quartile 1, quartile 3)] whole-body half-life [15.0 d (10.5, 72.6 d) compared with 135 d (115, 199 d); P = 0.0006], time-to-dose equilibration [3.40 d (3.14, 6.75 d) compared with 18.9 d (11.2, 25.7 d); P < 0.0001], and total traced mass [166 µmol VA (162, 252 µmol VA) compared with 476 µmol VA (290, 752 µmol VA); P = 0.0031].Conclusions: Extended RID sampling alters numerous mathematically modeled, time-dependent outcomes in women. Length of study should be considered when using mathematical models for calculating total-body VA stores or kinetic parameters related to VA turnover. This study is registered at www.clinicaltrials.gov as NCT03248700. [ABSTRACT FROM AUTHOR]

The article offers information on the report made by the United States Atomic Energy Commission regarding the domestic distribution of isotopes. It is noted that on August 2, 1946 the first sale of radioactive isotope produced from the uranium chain-reacting pile of the Clinton Laboratories initialized the peacetime applications of atomic energy. Some of the radioisotopes being used in fundamental research in medicine are radiogold, radiopotassium, radiosodium, radioiodine, and radiophosphorus. The transportation and proper handling of these radioactive substances is also elaborated.

Effective conservation of migratory bird populations depends on advancements in our understanding of processes throughout the life cycle. Fundamental information about wintering ecology (e.g., habitat use and diet composition) remains limited, which limits assessment of threats to populations during winter. Bobolink [Dolichonyx oryzivorus} is a year-round grassland obligate and Nearctic-Neotropical migrant that undergoes 2 complete molts each year, including a complete prealternate molt on the South American wintering grounds. This unusual winter molt provides a rare opportunity to examine, using stable isotope analysis, the timing and contribution of foraging resources in the Bobolink diet prior to northbound migration from disparate breeding populations. We compared winter diet composition among 3 breeding populations of Bobolinks and during 3 stages of winter molt using stable carbon isotope ratios. We used mixing models to compare the ratio of carbon-12 to carbon-13 isotope (S13C value) in feathers--grown on the wintering grounds but collected from individuals (n=105) breeding in Vermont, Nebraska, and North Dakota, USA--to estimate diet during early, middle, and late winter molt. Across the 3 breeding populations, Bobolinks relied on C3 sources for nearly one-third of their diet during the winter molt. Isotope data from feathers collected while growing on the wintering grounds from birds in rice vs. non-rice regions supported our assumption that C3 signatures are primarily due to a rice diet. The proportion of rice consumed was highest during late molt, corresponding with a period of greater rice availability to Bobolinks. Our results demonstrate that rice was a substantial component of the diet throughout the winter molt and was most exploited prior to northbound migration. Research is needed on the potential trade-offs of feeding on abundant cultivated rice, including its nutritional value and associated risks and conflicts from foraging in an agricultural setting. [ABSTRACT FROM AUTHOR]

The article presents a timeline of the history of the Fast Flux Test Facility (FFTF) of the U.S. Construction of the plutonium breeder reactor program started in December 1970. Congress ends funding for the Clinch River reactor in November 1983. A Tri-Party Agreement was signed by the Energy Department with the Environmental Protection Agency and the Washington State Ecology Department to clean up the Hanford site. During operations, the FFTF produced isotopes for medical and industrial purposes, tritium for the U.S. fusion research program and conducted research for Japan's breeder program.

Beginning with the foundation date of Spanish Tucson in 1775 and continuing through the 1890s, shallow groundwater and related features, including a perched aquifer, stream-bed springs and a short perennial reach in the Santa Cruz River, progressively disappeared from the Downtown Tucson area. The 20th-Century city grew rapidly, and increasing groundwater withdrawals caused large declines in the regional aquifer of Tucson basin, leaving a second perched aquifer with non-aqueous contaminants beneath Downtown. Isotope data show that this fully perched aquifer retains residual water from the regional aquifer, plus recharge derived from a nearby small watercourse. The present regional aquifer beneath Downtown is locally layered and partly confined, and contains water 7-20 Ka years old originating at the northern and southeastern basin margins. [ABSTRACT FROM AUTHOR]

There is continued emphasis from the various worldwide regulatory agencies to ensure that the pharmaceutical industry fully understands the products they are developing. This emphasis is seen via development of quality-by-design (QbD) publications and guidelines generated by the International Committee on Harmonization. The challenge to meet these expectations is primarily associated with the generation of in vivo data (eg, pharmacokinetic data) that is resource intensive. A technique reducing the resources needed to generate this in vivo data permits a more extensive application of QbD principles. This paper presents the application of stable isotopes in pharmacokinetic studies. The data show that the use of stable isotopes can significantly reduce the number of subjects required for a study. This reduction in subjects thus translates into a significant reduction in resources and time needed to generate the required in vivo data to support QbD. [ABSTRACT FROM AUTHOR]

Purpose: The present study aimed to establish and validate an isotope-dilution-UHPLC-MS/MS method for the determination of perampanel (PER) concentration and investigate the effect of eslicarbazepine acetate (ESL) on the pharmacokinetics of PER in rats., Methods: The rats were randomly divided into the control (0.5% CMC-Na) and experimental groups (ESL, 72 mg/kg), with six rats in each group. A single dose of PER (1 mg/kg) was administered after a week of repetitive 0.5% CMC-Na or ESL dosing (72 mg/kg); then, plasma samples were collected. Perampanel-d 5 (PER-d 5 ) was used as the internal standard (IS), liquid-liquid extraction of plasma samples was carried out using ethyl acetate, and chromatographic separation was carried out on a Titank C18 column (2.1 mm × 50 mm, 3.0 μm) using a gradient mobile phase consisting of 0.1% formic acid and acetonitrile at a flow rate of 0.3 mL/min., Results: PER had good linearity (0.3-600 ng/mL, r >0.999), and the accuracy, precision, recovery rate, and matrix effects (ME) met the Food and Drug Administration (FDA) guidelines. Compared to the control group, the area under the curve AUC 0→t, AUC 0→∞ , and Cmax of PER in the experimental group decreased by 30.28%, 30.34%, and 46.94%, respectively, and CL increased by 32.08%., Conclusion: ESL could induce the metabolism of PER in rats and decreases plasma exposure to PER. Thus, the concomitant treatment with ESL may require a high dose of PER to achieve the same efficacy., Competing Interests: The authors report no conflicts of interest in this study., (© 2022 Liu et al.)

Introduction of non-native species is a leading threat to global aquatic biodiversity. Competition between native and non-native species is often influenced by changes in suitable habitat or food availability. We investigated diet breadth and degree of trophic niche overlap for a fish assemblage of native and non-native species inhabiting a shallow, high elevation lake system. This assemblage includes one of the last remaining post-glacial endemic populations of adfluvial Arctic grayling (Thymallus arcticus) in the contiguous United States. We examined gut contents and stable isotope values of fish taxa in fall and spring to assess both short- (days) and long-term (few months) changes in trophic niches. We incorporate these short-term (gut contents) data into a secondary isotope analysis using a Bayesian statistical framework to estimate long-term trophic niche. Our data suggest that in this system, Arctic grayling share both a short- and long-term common food base with non-native trout of cutthroat x rainbow hybrid species (Oncorhynchus clarkia bouvieri x Oncorhynchus mykiss) and brook trout (Salvelinus fontinalis). In addition, trophic niche overlap among Arctic grayling, hybrid trout, and brook trout appeared to be stronger during spring than fall. In contrast, the native species of Arctic grayling, burbot (Lota lota), and suckers (Catostomus spp.) largely consumed different prey items. Our results suggest strong seasonal differences in trophic niche overlap among Arctic grayling and non-native trout, with a potential for greatest competition for food during spring. We suggest that conservation of endemic Arctic grayling in high-elevation lakes will require recognition of the potential for coexisting non-native taxa to impede well-intentioned recovery efforts. [ABSTRACT FROM AUTHOR]

Geospatially distributed isotopes (isoscapes) from biogeochemically fractionated processes have been applied in many forensic investigations, such as authentication of food and sourcing of drugs. Provenancing of human remains using isotopes has been hindered by a lack of appropriate isoscapes, by changes in these isoscapes over time, and by various homogenization processes. In this study we create spatiotemporal isoscapes for anthropogenic lead (Pb) for the contiguous United States and Europe using literature data from dated sediments, soils and biological tissues. We compare (206)Pb/(207)Pb isoscapes with isoscapes of δ(13)C, δ(18)O and (87)Sr/(86)Sr to determine their relative efficacy for the forensic identification of human remains. We do this comparison using third molar enamel data from 22 United States Air Force Academy cadets with known life trajectories born between 1983 and 1985. We use these spatiotemporal isoscapes with osteologic analyses, hospital records and isotopic analyses of tooth enamel carbonate from permanent teeth to help identify 32 individuals from unmarked graves found in a forgotten 19th century mental asylum cemetery. [ABSTRACT FROM AUTHOR]

Objectives We conducted stable isotope and dietary analyses of women from higher and lower socioeconomic status (SES) groups in Cali, Colombia. The objectives were to test between-group differences in stable isotope, dietary, and anthropometric characteristics, and to evaluate relationships between diet and stable isotope values. Methods Hair samples from 38 women (mean age 33.4) from higher and lower SES groups were analyzed for δ13C, δ15N, and δ34S values. Dietary intake was assessed via 24-h recalls. Anthropometric variables measured were body mass index, five body circumferences, and six skinfold thicknesses. Results Mean δ13C and δ15N values of the higher SES group (−16.4 and 10.3‰) were significantly greater than those of the lower SES group (−17.2 and 9.6‰; P < 0.01), but mean δ34S values did not differ significantly between groups (higher SES: 4.6‰; lower SES: 5.1‰). The higher SES group consumed a greater percentage of protein than the lower SES group (14% vs. 12% of energy; P = 0.03), but the groups did not differ in other dietary characteristics or in anthropometric characteristics. δ13C, δ15N, and δ34S values were not correlated with intake of the dietary items predicted (sugars, animal-source protein, and marine foods, respectively). The lower SES group was more variable in all three stable isotope values ( P < 0.05), mirroring a trend toward greater dietary variability in this group. Conclusions Stable isotope values revealed a difference between SES groups that was not explained by the dietary data. The relationship between diet and stable isotope composition is complex. Am. J. Hum. Biol. 27:207-218, 2015. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Lakes and streams in Class 1 wilderness areas in the western United States (U.S.) are at risk from atmospheric deposition of nitrogen (N) and sulfur (S), and protection of these resources is mandated under the Federal Clean Air Act and amendments. Assessment of critical loads, which are the maximum exposure to pollution an area can receive without adverse effects on sensitive ecosystems, requires accurate deposition estimates. However, deposition is difficult and expensive to measure in high-elevation wilderness, and spatial patterns in N and S deposition in these areas remain poorly quantified. In this study, ion-exchange resin (IER) collectors were used to measure dissolved inorganic N (DIN) and S deposition during June 2006–September 2007 at approximately 20 alpine/subalpine sites spanning the Continental Divide in Rocky Mountain National Park. Results indicated good agreement between deposition estimated from IER collectors and commonly used wet + dry methods during summer, but poor agreement during winter. Snowpack sampling was found to be a more accurate way of quantifying DIN and S deposition during winter. Summer DIN deposition was significantly greater on the east side of the park than on the west side (25–50%; p ≤ 0.03), consistent with transport of pollutants to the park from urban and agricultural areas to the east. Sources of atmospheric nitrate (NO 3 − ) were examined using N isotopes. The average δ 15 N of NO 3 − from IER collectors was 3.5‰ higher during winter than during summer ( p < 0.001), indicating a seasonal shift in the relative importance of regional NO x sources, such as coal combustion and vehicular sources of atmospheric NO 3 − . There were no significant differences in δ 15 N of NO 3 − between east and west sides of the park during summer or winter ( p = 0.83), indicating that the two areas may have similar sources of atmospheric NO 3 − . Results from this study indicate that a combination of IER collectors and snowpack sampling can be used to characterize spatial variability in DIN and S deposition in high-elevation wilderness areas. These data can improve our ability to model critical loads by filling gaps in geographic coverage of deposition monitoring/modeling programs and thus may enable policy makers to better protect sensitive natural resources in Class 1 Wilderness areas. [ABSTRACT FROM AUTHOR]

In the western U.S., the mismatch between public water demands and natural water availability necessitates large interbasin transfers of water as well as groundwater mining of fossil aquifers. Here we identify probable situations of nonlocal water use in both space and time based on isotopic comparisons between tap waters and potential water resources within hydrologic basins. Our approach, which considers evaporative enrichment of heavy isotopes during storage and distribution, is used to determine the likelihood of local origin for 612 tap water samples collected from across the western U.S. We find that 64% of samples are isotopically distinct from precipitation falling within the local hydrologic basin, a proxy for groundwater with modern recharge, and 31% of samples are isotopically distinct from estimated surface water found within the local basin. Those samples inconsistent with local water sources, which we suggest are likely derived from water imported from other basins or extracted from fossil aquifers, are primarily clustered in southern California, the San Francisco Bay area, and central Arizona. Our isotope-based estimates of nonlocal water use are correlated with both hydrogeomorphic and socioeconomic properties of basins, suggesting that these factors exert a predictable influence on the likelihood that nonlocal waters are used to supply tap water. We use these basin properties to develop a regional model of nonlocal water resource use that predicts ( r2 = 0.64) isotopically inferred patterns and allows assessment of total interbasin transfer and/or fossil aquifer extraction volumes across the western U.S. [ABSTRACT FROM AUTHOR]

This study revises and improves the chrono-stratigraphic framework for late Turonian through early Campanian time based on work in the Western Interior U.S. and introduces new methods to better quantify uncertainties associated with the development of such time scales. Building on the unique attributes of the Western Interior Basin, which contains abundant volcanic ash beds and rhythmic strata interpreted to record orbital cycles, we integrate new radioisotopic data of improved accuracy with a recently published astrochronologic framework for the Niobrara Formation. New 40Ar/39Ar laser fusion ages corresponding to eight different ammonite biozones are determined by analysis of legacy samples, as well as newly collected material. These results are complemented by new U-Pb (zircon) chemical abrasion-isotope dilution-thermal ionization mass spectrometry ages from four biozones in the study interval. When combined with published radioisotopic data from the Cenomanian-Turonian boundary, paired 206Pb/238U and 40Ar/39Ar ages spanning Cenomanian to Campanian time support an astronomically calibrated Fish Canyon sanidine standard age of 28.201 Ma. Stage boundary ages are estimated via integration of new radioisotopic data with the floating astrochronology for the Niobrara Formation. The ages are determined by anchoring the long eccentricity bandpass from spectral analysis of the Niobrara Formation to radioisotopic ages with the lowest uncertainty proximal to the boundary, and adding or subtracting time by parsing the 405 k.y. cycles. The new stage boundary age determinations are: 89.75 ± 0.38 Ma for the Turonian-Coniacian, 86.49 ± 0.44 Ma for the Coniacian-Santonian, and 84.19 ± 0.38 Ma for the Santonian-Campanian boundary. The 2σ uncertainties for these estimates include systematic contributions from the radioisotopic measurements, astrochronologic methods, and geologic uncertainties (related to stratigraphic correlation and the presence of hiatuses). The latter geologic uncertainties have not been directly addressed in prior time scale studies and their determination was made possible by critical biostratigraphic observations. Each methodological approach employed in this study--new radioisotopic analysis, stratigraphic correlation, astrochronology, and ammonite and inoceramid biostratigraphy--was critical for achieving the final result. [ABSTRACT FROM AUTHOR]

Abstract: Small-basin floodplain buried soils formed in association with low-order tributary streams are valuable archives of past climates, but have not been studied extensively in central Texas, USA. Four buried soils exposed along Owl Creek, within the larger Brazos River drainage basin, were examined using soil morphology and micromorphology, optically stimulated luminescence (OSL) dating, soil characterization, whole-soil geochemical and stable isotope analyses of soil organic matter and pedogenic carbonate. These buried soils provide a record of changes in paleoecological and paleo-alluvial conditions spanning ~14ky. Morphological and geochemical differences between buried soils reflect changes in landscape attributable to climate, with a distinct 5‰ increase in δ13C values of soil organic matter corresponding to the Holocene onset and drier conditions. Paleoecological reconstructions coupled with depth to Bk suggest possible amounts of erosion of ~1m for each of the buried soils. Compilation of the proxies presented shows evidence for a cooler and wetter late Pleistocene climate, followed by a warmer and drier climate dominating during the Holocene. [Copyright &y& Elsevier]

Background: The maximal calcium absorption in response to vitamin D has been proposed as a biomarker for vitamin D sufficiency. Objective: The objective was to determine whether there is a threshold beyond which increasing doses of vitamin D, or concentrations of serum 25-hydroxyvitamin D [25(OH)D], no longer increase calcium absorption. Design: This was a placebo-controlled, dose-response, randomized, double-blind study of the effect of vitamin D on calcium absorption in healthy postmenopausal women. Seventy-six healthy postmenopausal women were randomly assigned to placebo or 800 IU (20 mg), 2000 IU (50 µg), or 4000 IU (100 µg) vitamin D3 for 8 wk. The technique of dual isotopes of stable calcium was used with a calcium carrier to measure calcium absorption at baseline and after 8 wk. Results: Seventy-one women with a mean ± SD age of 58.8 ± 4.9 y completed the study. The mean calcium intake was 1142 6 509 mg/d and serum 25(OH)D was 63 ± 14 nmol/L at baseline. A statistically significant linear trend of an increase in calcium absorption adjusted for age and body mass index with increasing vitamin D3 dose or serum 25(OH)D concentration was observed. A 6.7% absolute increase in calcium absorption was found in the highest vitamin D3 group (100 µg). No evidence of nonlinearity was observed in the dose-response curve. Conclusions: No evidence of a threshold of calcium absorption was found with a serum 25(OH)D range from 40 to 130 nmol/L. Calcium absorption in this range is not a useful biomarker to determine nutritional recommendations for vitamin D. This trial was registered at clinicaltrials. gov as NCT01119378. [ABSTRACT FROM AUTHOR]

• Electromagnetic stirring (EMS) increases isotopic homogeneity in downblend casting. • The use of zirconia crucibles enables electromagnetic stirring. • Sampling of U-10Mo for uranium enrichment measurements should be done after homogenization. Uranium alloyed with 10 wt percent molybdenum (U-10Mo) is the proposed fuel for use in the United States' high-performance research reactors. The U-10Mo fuel is fabricated by a two-step casting process that downblends highly enriched uranium with depleted uranium (DU) and/or natural uranium (NU) and subsequently alloys the resulting high-assay low-enriched uranium (HALEU) with Mo. Currently, a two-step casting process is needed to meet the ingots' U-235 enrichment homogeneity specifications. This work demonstrates the ability to provide more homogeneous U-235 distributions during downblend casting by using zirconia for crucibles rather than graphite. When graphite is used as a crucible, the electromagnetic field produced by the induction heater couples directly with the graphite. Zirconia is nonconducting in this study, and therefore does not couple with the field. The induction field couples directly with the metal, and causes electromagnetic stirring (EMS) in the molten metal pool. Eight downblend casting experiments were carried out in this work. Four were performed with zirconia crucibles and four with graphite crucibles. The U-235 enrichment was measured at nine discrete points in each casting using laser ablation multi-collector inductively coupled mass spectrometry (LA-MC-ICP-MS). The enrichment homogeneity was approximately eight times better in zirconia crucible castings than in graphite crucible castings as measured by the plate enrichment range and enrichment coefficient of variation. The results show a single casting step could be used to meet USHPRR enrichment specifications if electromagnetic stirring is present during casting. A related investigation was carried out to determine whether it is appropriate to measure enrichment on as-cast ingots or whether heat treated specimens should be used to accurately characterize enrichment. The results show that the as-cast microstructure plays a significant role in enrichment homogeneity. It is recommended that all enrichment measurements be done after the homogenization heat treatment typical of U-10Mo processing. [ABSTRACT FROM AUTHOR]

A large-eddy simulation model developed at the National Center for Atmospheric Research (NCAR) is extended to simulate the transport and diffusion of COO, HO and CO in the atmospheric boundary layer (ABL). The simulation results show that the O compositions of leaf water and the ABL CO are moderately sensitive to wind speed. The variations in the O composition of water vapour are an order of magnitude greater than those in the C and O compositions of CO both at turbulent eddy scales and across the capping inversion. In a fully-developed convective ABL, these isotopic compositions are well mixed as with other conserved atmospheric quantities. The Keeling intercepts determined with the simulated high-frequency turbulence time series do not give a reliable estimate of the O composition of the surface water vapour flux and may be a reasonable approximation to the C and O compositions of the surface CO flux in the late afternoon only after a deep convective ABL has developed. We suggest that our isotopic large-eddy simulation (ISOLES) model should be a useful tool for testing and formulating research hypotheses on land-air isotopic exchanges. [ABSTRACT FROM AUTHOR]

Oak forests dominate much of the eastern USA, but their future is uncertain due to a number of threats and widespread failure of oak regeneration. A sudden loss of oaks (Quercus spp.) could be accompanied by major changes in forest nitrogen (N) cycles with important implications for plant nutrient uptake and tree species composition. In this study, we measured the changes in N use and growth rates of black birch trees (Betula lenta L.) following oak girdling at the Black Rock Forest in southeastern New York, USA. Data were collected from nine experimental plots composed of three treatments: 100% oaks girdled (OG), 50% oaks girdled (O50) and control (C). Foliar N concentration and foliar 15N abundance increased significantly in the oak-girdled plots relative to the control, indicating that the loss of oaks significantly altered N cycling dynamics. As mineralization and nitrification rates increase following oak loss, black birch trees increase N absorption as indicated by higher foliar N content and increased growth rates. Foliar N concentration increased by 15.5% in the O50 and 30.6% in the OG plots relative to the control, while O50 and OG plots were enriched in 15N by 1.08‰ and 3.33‰, respectively (P < 0.0001). A 641% increase in black birch growth rates in OG plots suggests that this species is able to respond to additional N availability and/or increased light availability. The loss of oaks and subsequent increase in black birch productivity may have a lasting impact on ecosystem form and function. [ABSTRACT FROM AUTHOR]

An understanding of the factors influencing the isotopic composition of body water is important to determine the isotopic composition of tissues that are used to reconstruct movement patterns of humans. The δ2H and δ18O values of body water (δ2Hbw and δ18Obw) are related to the δ2H and δ18O values of drinking water (δ2Hdw and δ18Odw), but clearly distinct because of other factors including the composition of food. Here, we develop a mechanistic geographical information system (GIS) model to produce spatial projections of δ2Hbw and δ18Obw values for the USA. We investigate the influence of gender, food, and drinking water on the predicted values by comparing them with the published values. The strongest influence on the predicted values was related to the source of δ2Hdw and δ18Odw values. We combine the model with equations that describe the rate of turnover to produce estimates for the time required for a non-resident to reach an isotopic equilibrium with a resident population. [ABSTRACT FROM AUTHOR]

This study presents an example of using well-constrained stratigraphic trends in carbon isotope composition of marine carbonate deposits as a tool for high-resolution correlation of successions that lack prominent biomarkers. A large, positive carbon isotope excursion is recorded within the Steptoean (Furongian, Upper Cambrian) strata of the southern Appalachians in Tennessee. A coeval excursion (also known as SPICE) has been reported for the western United States (the Great Basin area), China, Kazakhstan, and Australia, indicating that this is a global phenomenon. The anatomy of this excursion was determined through extensive sampling of homogenous micrite and dolomicrite from strata at the Thorn Hill locality in northeastern Tennessee. The δC values show an increase from the upper Nolichucky Shale into the overlying Maynardville Formation (Conasauga Group). The most positive δC values (+4 to +5 ‰ VPDB) correspond to the transition between the Maynardville and the Copper Ridge Dolomite (Knox Group). The δC values decline in the lower part of the Copper Ridge. This characteristic carbon isotope record is compared with the δC record from the Lee Valley locality, which is about 30 km away and contains a coeval succession of strata that represent similar carbonate platform depositional environments. A comparison of the δC records shows a remarkable similarity and provides the means for detailed correlation of these two stratigraphic successions. Next the results are compared with those from the Tazewell locality, which is in the northwesternmost outcrop belt of lower Paleozoic rocks in Tennessee. This section is separated from the Thorn Hill and Lee Valley sections by three thrust faults and is truncated at the base by a thrust fault. The strata at the Tazewell locality differ from those at Thorn Hill and Lee Valley in that they were deposited more closely to the carbonate platform margin. Despite these differences, carbon isotope records proved very useful for correlation among the three successions. The results of this study encourage application of similar approaches in correlation of Steptoean strata at more widely spaced outcrops within and beyond the Appalachian basin. [ABSTRACT FROM AUTHOR]

n understanding of atmospheric water vapor content and its isotopic composition is important if we are to be able to model future water vapor dynamics and their potential feedback on future climate change. Here we present diurnal and vertical patterns of water isotope ratios in forest air (δH and δO) not observed previously. Water vapor observed at three heights over 3 consecutive days in a coniferous forest in the Pacific Northwest of the United States, shows a stratified nocturnal structure of δH and δO, with the most positive values consistently observed above the canopy (60 m). Differences between 0.5 m and 60 m range between 2-6‰ for δO and 20-40‰ for δH at night. Using a box model, we simulated HO isotope fluxes and showed that the low to high δH and δO profiles can be explained by the vapor flux associated with evaporation from the forest floor and canopy transpiration. We used d-excess as a diagnostic tracer to identify processes that contribute to the diurnal variation in atmospheric moisture. Values of d-excess derived from water vapor measurements showed a repeated diel pattern, with the lowest values occurring in the early morning and the highest values occurring at midday. The isotopic composition of rain water, collected during a light rain event in the first morning of our experiment, suggested that considerable below-cloud secondary evaporation occurred during the descent of raindrops. We conclude that atmospheric entrainment appears to drive the isotopic variation of water vapor in the early morning when the convective boundary layer rapidly develops, while evapotranspiration becomes more important in the mid-afternoon as a primary moisture source of water vapor in this forest. Our results demonstrate the interplay between the effects of vegetation and boundary layer mixing under the influence of rain evaporation, which has implications for larger-scale predictions of precipitation across the terrestrial landscape. [ABSTRACT FROM AUTHOR]

The Radiochemical Engineering Development Center (REDC) at the Oak Ridge National Laboratory is the production, storage, and distribution center for the heavy-element research program of the U.S. Department of Energy. The REDC and the neighboring High Flux Isotope Reactor (HFIR) were built to produce quantities of transuranium elements for use in national and international research programs and since 1966 has been the main center of production for transcurium elements in the United States. In 2009, REDC successfully completed Campaign 74, its latest Bk-249/Cf-252 production campaign. The Transuranium Analytical Laboratory (TAL), located within REDC, provides the needed chemical and radiochemical analyses on a wide variety of nuclear matrixes in support of these production campaigns of transcurium isotopes. Titrations, dissolutions, separations, and dilutions of high activity samples are completed in hot-cells and glove-boxes in preparation for analytical radiochemistry determinations completed at the TAL in support of the REDC's mission. Within Campaign 74, the Transuranium Analytical Laboratory implemented a quick and reliable radiochemical method for the determination of Bk-249 that was used throughout the purification process at key hold points to ensure the delivery of a final purified product. [ABSTRACT FROM AUTHOR]

The structure and function of a microbial community capable of biodegrading methyl- tert-butyl ether (MTBE) was characterized using compound-specific stable isotope analysis (CSIA), clone libraries and stable isotope probing of proteins (Protein-SIP). The enrichment culture (US3-M), which originated from a gasoline-impacted site in the United States, has been enriched on MTBE as the sole carbon source. The slope of isotopic enrichment factors (ℇC of −2.29±0.03‰; ℇH of −58±6‰) for carbon and hydrogen discrimination (Δδ2H/Δδ13C) was on average equal to Λ=24±2, a value closely related to the reaction mechanism of MTBE degradation in Methylibium petroleiphilum PM1. 16S rRNA gene libraries revealed sequences belonging to M. petroleiphilum PM1, Hydrogenophaga sp., Thiothrix unzii, Rhodobacter sp., Nocardiodes sp. and different Sphingomonadaceae bacteria. Protein-SIP analysis of the culture grown on 13C-MTBE as the only carbon source revealed that proteins related to members of the Comamonadaceae family, such as Delftia acidovorans, Acidovorax sp. or Comamonas sp., were not 13C-enriched, whereas proteins related to M. petroleiphilum PM1 showed an average incorporation of 94.5 atom%13C. These results indicate a key role for this species in the degradation of MTBE within the US3-M consortia. The combination of CSIA, molecular biology and Protein-SIP facilitated the analysis of an MTBE-degrading mixed culture from a functional and phylogenetic point of view. [ABSTRACT FROM AUTHOR]

The regional carbonate aquifer in the carbonate-rock province of the Great Basin, USA, covers thousands of square kilometers. It is a significant potential source of water for growth in this arid area. Few wells penetrate the carbonate aquifer, so information on water quantity and quality is derived in large part from ‘regional springs’ that discharge from regional interbasin flow systems. For this study, springs in the carbonate-rock province were sampled; their physical, chemical, and isotopic characteristics were compared to those of known regional springs to identify previously unrecognized regional waters using both examination of the data and multivariate statistical analysis. Criteria for comparison included temperature, discharge, 3H activity, carbon isotope values, and ratios of major and trace ions. Of the 18 springs selected for detailed chemical and isotopic sampling, five springs—Hot, Littlefield, Petrified, Saratoga, and Warm (a)—were identified as regional, and one (Monte Neva Hot) was identified as a possible regional spring. Regional springs provide an easy, low-cost means of investigating aquifer properties; identification of regional springs thus increases the ability to understand the regional carbonate aquifer. The techniques applied in this study can also be used in other regional aquifer systems with diverse and complex geology. [ABSTRACT FROM AUTHOR]

In this study, coupled Pb concentration/Pb isotope data were used to evaluate the effect of a shooting range (operational for over 30 years) on Pb contamination of adjacent agricultural soils and the associated environmental risks. Lead was mainly concentrated in the arable layer of the contaminated agricultural soils at total concentrations ranging from 573 to 694 mg kg − 1. Isotopic analyses (206Pb/207Pb) proved that Pb originated predominantly from the currently used pellets. Chemical fractionation analyses showed that Pb was mainly associated with the reducible fraction of the contaminated soil, which is in accordance with its predominant soil phases (PbO, PbCO3). The 0.05 M EDTA extraction showed that up to 62% of total Pb from the contaminated site is potentially mobilizable. Furthermore, Pb concentrations obtained from the synthetic precipitation leaching procedure extraction exceeded the regulatory limit set by the United States Environmental Protection Agency for drinking water. Ion exchange resin bags showed to be inefficient for determining the vertical distribution of free Pb2 + throughout the soil profile. Increased Pb concentrations were found in the biomass of spring barley ( Hordeum vulgare L.) sampled at the studied site and two possible pathways of Pb uptake have been identified: (1) through passive diffusion-driven uptake by roots and (2) especially through atmospheric deposition, which was also proved by analyses of a bioindicator species (bryophyte Hypnum cupressiforme Hedw.). This study showed that shooting ranges can present an important source of Pb contamination of agricultural soils located in their close vicinity. [ABSTRACT FROM AUTHOR]

Reductions in the size of the U.S. nuclear weapons arsenal resulted in the need to store large quantities of plutonium-bearing metals and oxides for prolonged periods of time. To assure that the excess plutonium from the U.S. Department of Energy (DOE) sites was stored in a safe and environmentally friendly manner the plutonium- bearing materials are stabilized and packaged according to well-developed criteria published as a DOE standard. The packaged materials are stored in secure facilities and regular surveillance activities are conducted to assure continuing package integrity. The stabilization, packaging, storage, and surveillance requirements were developed through extensive science and engineering activities including those related to plutonium-environment interactions and container pressurization, corrosion and stress-corrosion cracking, plutonium-container material interactions, loss of sealing capability, and changes in heat transfer characteristics. This paper summarizes some of those activities and outlines ongoing science and engineering programs that assure continued safe and secure storage of the plutonium-bearing metals and oxides. [ABSTRACT FROM AUTHOR]

Information about the international forum on the problems with irradiators is presented. The irradiation of cell concentrates in Japan is due to the high risk of transfusion-associated graft-versus-host disease (GVHD). Agencies or manufacturers find it difficult to repair and obtain new irradiators when it break down. The phase-out of Cs-137 irradiators is recommended by the U.S. Nuclear Regulatory Commission Task force to prevent terrorists from the use of isotopes.

Argonne National Laboratory of the United States and Kharkov Institute of Physics and Technology of Ukraine have been collaborating on the conceptual design development of an electron accelerator-driven subcritical facility. The facility will be utilized for performing basic and applied nuclear research, producing medical isotopes, and training young nuclear specialists. This paper presents the design and analyses of the biological shield performed for the top section of the facility. The neutron source driving the subcritical assembly is generated from the interaction of a 100-kW electron beam with a natural uranium target. The electron energy is in the range of 100 to 200 MeV, and it has a uniform spatial distribution. The shield design and the associated analyses are presented including different parametric studies. In the analyses, a significant effort was dedicated to the accurate prediction of the radiation dose outside the shield boundary as a function of the shield thickness without geometrical approximations or material homogenization. The MCNPX Monte Carlo code was utilized for the transport calculation of electrons, photons, and neutrons. Weight window variance-reduction techniques were introduced, and the dose equivalent outside the shield can be calculated with reasonably good statistics. [ABSTRACT FROM AUTHOR]

Time series of data from radiation portal monitors are evaluated for radioactive sources by comparing background to vehicle spectra over time with a “spectral-distance” metric, isolating the contribution of anomalous radiation. This may diminish systematic fluctuations from vehicular background attenuation and allow time-shape filtering for discriminating compact sources. To examine this, a wavelet function similar in size to the expected source profile filters the spectral-distance output. Spectra from chosen isotopes are injected into data from a U.S. port of entry. The resulting data are analyzed with gross-counting, spectral-distance, and spatial algorithms. Combined spectral/spatial filtering is shown to enhance sensitivity and discrimination of compact versus distributed sources. [ABSTRACT FROM AUTHOR]

Neotropical migratory songbirds typically breed in temperate regions and then travel long distances to spend the majority of the annual cycle in tropical wintering areas. Using stable-isotope methodology, we provide quantitative evidence of dual breeding ranges for 5 species of Neotropical migrants. Each is well known to have a Neotropical winter range and a breeding range in the United States and Canada. However, after their first bout of breeding in the north, many individuals migrate hundreds to thousands of kilometers south in midsummer to breed a second time during the same summer in coastal west Mexico or Baja California Sur. They then migrate further south to their final wintering areas in the Neotropics. Our discovery of dual breeding ranges in Neotropical migrants reveals a hitherto unrealized flexibility in life-history strategies for these species and underscores that demographic models and conservation plans must consider dual breeding for these migrants. [ABSTRACT FROM AUTHOR]

The article presents a comparative analysis of the history of isotope research programs designed for both biomedical and industrial applications in the United States, Great Britain, and France from 1945 to 1965. The author focuses particularly on the European isotope industry, especially the radioisotope distribution networks, the creation of training sites for research of radioisotopes, and scholarly publications which focused on isotope research or the use of isotopes as research tools. The author compares the success and productivity of the scientific research by considering evidence of material resources, workforce, and knowledge.

The article explores how the patent process impacted the development of the isotope industry from 1930 to 1960. The author focuses on the granting of patents to Italian physicist Enrico Fermi for his isotope research, considers the government policies of the U.S., Great Britain, and Canada regarding isotope research after World War II, and explores the legal problems faced by Philips Research Laboratories in maintaining their rights to patents they owned after government legislation was enacted that limited ownership of nuclear technologies. Other subjects discussed include the U.S. McMahon Act, also known as the Atomic Energy Act of 1946, the U.S. Patent Compensation Board, the U.S. Atomic Energy Commission, and the Manhattan Project.

Abstract: The upper Klamath River experiences a cyanobacterial algal bloom and poor water quality during the summer. Diel chemical and isotopic techniques have been employed in order to investigate the rates of biogeochemical processes. Four diel measurements of field parameters (temperature, pH, dissolved oxygen concentrations, and alkalinity) and stable isotope compositions (dissolved oxygen–δ 18O and dissolved inorganic carbon–δ 13C) have been performed between June 2007 and August 2008. Significant diel variations of pH, dissolved oxygen (DO) concentration, and DO–δ 18O were observed, due to varying rates of primary productivity vs. respiration vs. gas exchange with air. Diel cycles are generally similar to those previously observed in river systems, although there are also differences compared to previous studies. In large part, these different diel signatures are the result of the low turbulence of the upper Klamath River. Observed changes in the diel signatures vs. sampling date reflect the evolution of the status of the algal bloom over the course of the summer. Results indicate the potential utility of applying diel chemical and stable isotope techniques to investigate the rates of biogeochemical cycles in slow-moving rivers, lakes, and reservoirs, but also illustrate the increased complexity of stable isotope dynamics in these low-turbulence systems compared to well-mixed aquatic systems. [Copyright &y& Elsevier]