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Sample records for 14c 26al 36cl

  1. Age and geomorphic history of Meteor Crater, Arizona, from cosmogenic 36Cl and 14C in rock varnish

    USGS Publications Warehouse

    Phillips, F.M.; Zreda, M.G.; Smith, S.S.; Elmore, D.; Kubik, P.W.; Dorn, R.I.; Roddy, D.J.

    1991-01-01

    Using cosmogenic 36Cl buildup and rock varnish radiocarbon, we have measured the exposure age of rock surfaces at Meteor Crater, Arizona. Our 36Cl measurements on four dolomite boulders ejected from the crater by the impact yield a mean age of 49.7 ?? 0.85 ka, which is in excellent agreement with an average age of 49 ?? 3 ka obtained from thermoluminescence studies on shock-metamorphosed dolomite and quartz. These ages are supported by undetectably low 14C in the oldest rock varnish sample. ?? 1991.

  2. "Groundwater ages" of the Lake Chad multi-layer aquifers system inferred from 14C and 36Cl data

    NASA Astrophysics Data System (ADS)

    Bouchez, Camille; Deschamps, Pierre; Goncalves, Julio; Hamelin, Bruno; Seidel, Jean-Luc; Doumnang, Jean-Claude

    2014-05-01

    Assessment of recharge, paleo-recharge and groundwater residence time of aquifer systems of the Sahel is pivotal for a sustainable management of this vulnerable resource. Due to its stratified aquifer system, the Lake Chad Basin (LCB) offers the opportunity to assess recharge processes over time and to link climate and hydrology in the Sahel. Located in north-central Africa at the fringe between the Sahel and the Sahara, the lake Chad basin (LCB) is an endorheic basin of 2,5.106 km2. With a monsoon climate, the majority of the rainfall occurs in the southern one third of the basin, the Chari/Logone River system transporting about 90% of the runoff generated within the drainage basin. A complex multi-layer aquifer system is located in the central part of the LCB. The Quaternary unconfined aquifer, covering 500 000 km2, is characterized by the occurrence of poorly understood piezometric depressions. Artesian groundwaters are found in the Plio-Pleistocene lacustrine and deltaic sedimentary aquifers (early Pliocene and Continental Terminal). The present-day lake is in hydraulic contact with the Quaternary Aquifer, but during past megalake phases, most of the Quaternary aquifer was submerged and may experience major recharge events. To identify active recharge area and assess groundwater dynamics, one hundred surface and groundwater samples of all layers have been collected over the southern part of the LCB. Major and trace elements have been analyzed. Measurements of 36Cl have been carried out at CEREGE, on the French 5 MV AMS National Facility ASTER and 14C activities have been analyzed for 17 samples on the French AMS ARTEMIS. Additionally, the stable isotopic composition was measured on the artesian aquifer samples. In the Quaternary aquifer, results show a large scatter with waters having very different isotopic and geochemical signature. In its southern part and in the vicinity of the surface waters, groundwaters are predominantly Ca-Mg-HCO3 type waters with very

  3. Erosion rate study at the Allchar deposit (Macedonia) based on radioactive and stable cosmogenic nuclides (26 Al, 36 Cl, 3 He, and 21 Ne)

    PubMed Central

    Cvetković, V.; Niedermann, S.; Pejović, V.; Amthauer, G.; Boev, B.; Bosch, F.; Aničin, I.; Henning, W. F.

    2016-01-01

    Abstract This paper focuses on constraining the erosion rate in the area of the Allchar Sb‐As‐Tl‐Au deposit (Macedonia). It contains the largest known reserves of lorandite (TlAsS2), which is essential for the LORanditeEXperiment (LOREX), aimed at determining the long‐term solar neutrino flux. Because the erosion history of the Allchar area is crucial for the success of LOREX, we applied terrestrial in situ cosmogenic nuclides including both radioactive (26Al and 36Cl) and stable (3He and 21Ne) nuclides in quartz, dolomite/calcite, sanidine, and diopside. The obtained results suggest that there is accordance in the values obtained by applying 26Al, 36Cl, and 21Ne for around 85% of the entire sample collection, with resulting erosion rates varying from several tens of m/Ma to ∼165 m/Ma. The samples from four locations (L‐8 CD, L1b/R, L1c/R, and L‐4/ADR) give erosion rates between 300 and 400 m/Ma. Although these localities reveal remarkably higher values, which may be explained by burial events that occurred in part of Allchar, the erosion rate estimates mostly in the range between 50 and 100 m/Ma. This range further enables us to estimate the vertical erosion rate values for the two main ore bodies Crven Dol and Centralni Deo. We also estimate that the lower and upper limits of average paleo‐depths for the ore body Centralni Deo from 4.3 Ma to the present are 250–290 and 750–790 m, respectively, whereas the upper limit of paleo‐depth for the ore body Crven Dol over the same geological age is 860 m. The estimated paleo‐depth values allow estimating the relative contributions of 205Pb derived from pp‐neutrino and fast cosmic‐ray muons, respectively, which is an important prerequisite for the LOREX experiment. PMID:27587984

  4. Testing the 14C ages and conservative behavior of dissolved 14C in a carbonate aquifer in Yucca Flat, Nevada (USA), using 36Cl from groundwater and packrat middens

    NASA Astrophysics Data System (ADS)

    Kwicklis, Edward; Farnham, Irene

    2014-09-01

    Corrected groundwater 14C ages from the carbonate aquifer in Yucca Flat at the former Nevada Test Site (now the Nevada National Security Site), USA, were evaluated by comparing temporal variations of groundwater 36Cl/Cl estimated with these 14C ages with published records of meteoric 36Cl/Cl variations preserved in packrat middens (piles of plant fragments, fecal matter and urine). Good agreement between these records indicates that the groundwater 14C ages are reasonable and that 14C is moving with chloride without sorbing to the carbonate rock matrix or fracture coatings, despite opposing evidence from laboratory experiments. The groundwater 14C ages are consistent with other hydrologic evidence that indicates significant basin infiltration ceased 8,000 to 10,000 years ago, and that recharge to the carbonate aquifer is from paleowater draining through overlying tuff confining units along major faults. This interpretation is supported by the relative age differences as well as hydraulic head differences between the alluvial and volcanic aquifers and the carbonate aquifer. The carbonate aquifer 14C ages suggest that groundwater velocities throughout much of Yucca Flat are about 2 m/yr, consistent with the long-held conceptual model that blocking ridges of low-permeability rock hydrologically isolate the carbonate aquifer in Yucca Flat from the outlying regional carbonate flow system.

  5. Depth-dependent Concentrations of Cosmogenic 10Be, 26Al, 36Cl, HEc, NEc, and ARc in the Old Woman Iron Meteorite

    NASA Astrophysics Data System (ADS)

    Lavielle, B.; Nishiizumi, K.; Marti, K.; Jeannot, J.-P.; Caffee, M. W.; Finkel, R. C.

    1995-09-01

    We report measurements of 1OBe7 26AI, 36CI, and of light noble gases in 6 samples of the type IIB Old Woman iron meteorite. The aim of this work is to study the depth dependence of the production rates of cosmogenic nuclides in iron meteorites. Old Woman is a large single mass of 2753 kg. Five samples have been taken from a slice of about 100 cm x 50 cm. One other sample was located roughly 40 cm above the center of the slice in a perpendicular direction. The distances between any two samples vary from 36.5 cm to 57.5 cm. Studies of cosmogenic nuclides in samples of known locations are very useful for the validation of models describing the production of cosmogenic nuclides in meteorites. Cosmogenic radionuclides were measured by accelerator mass spectrometry at Lawrence Livermore National Laboratory. Partial results have been reported earlier [1]. Concentrations of 4He, 21Ne and 38Ar in aliquots of the samples were determined by conventional mass spectrometry using an isotopic dilution method. The ratio 3He/4He appears to be almost constant with a value of 0.12 - ().13. This is about half the value generally observed in iron meteorites. Similar low ratios have been previously observed in some irons and in chondritic metal and reflect diffusion losses of 3H 12,31. The ratios 4He/38Ar, 4He/21Ne and 36Ar/38Ar are similar to those observed in iron meteorites indicating no significant losses of 4He. The measured ratio S = 4He/21Ne which represents one of the best indicators of shielding depth in iron meteorites, varies from 310 to 375 in samples from the slice. By using this as a shielding parameter, profiles were obtained for the different nuclides investigated in this work. Systematic decreases from the surface to the center of the meteorite are observed and the center of the meteoroid can be determined. As expected from nuclear systematics, the ratio 36Cl/36Ar is almost constant. The ratio 36Cl/10Be is relatively constant with a mean value of 4.7 indicating that the

  6. Production of cosmogenic isotopes 7Be, 10Be, 14C, 22Na, and 36Cl in the atmosphere: Altitudinal profiles of yield functions

    NASA Astrophysics Data System (ADS)

    Poluianov, S. V.; Kovaltsov, G. A.; Mishev, A. L.; Usoskin, I. G.

    2016-07-01

    New consistent and precise computations of the production of five cosmogenic radioisotopes, 7Be, 10Be, 14C, 22Na, and 36Cl, in the Earth's atmosphere by cosmic rays are presented in the form of tabulated yield functions. For the first time, a detailed set of the altitude profiles of the production functions is provided which makes it possible to apply the results directly as input for atmospheric transport models. Good agreement with most of the earlier published works for columnar and global isotopic production rates is shown. Altitude profiles of the production are important, in particular for such tasks as studies of strong solar particle events in the past, precise reconstructions of solar activity on long-term scale, tracing air mass dynamics using cosmogenic radioisotopes, etc. As an example, computations of the 10Be deposition flux in the polar region are shown for the last decades and also for a period around 780 A.D. and confronted with the actual measurements in Greenland and Antarctic ice cores.

  7. Multiple dating approach (14C, U/Th and 36Cl) of tsunami-transported reef-top megaclasts on Bonaire (Leeward Antilles) - potential and current limitations

    NASA Astrophysics Data System (ADS)

    Rixhon, Gilles; May, Simon Matthias; Engel, Max; Mechernich, Silke; Keulertz, Rebecca; Schroeder-Ritzrau, Andrea; Fohlmeister, Jens; Frank, Norbert; Dunai, Tibor; Brueckner, Helmut

    2016-04-01

    Coastal hazard assessment depends on reliable information on the magnitude and frequency of past high-energy wave events (EWE: tsunamis, storms). For this purpose onshore sedimentary records represent promising geo-archives for the mid- and late-Holocene EWE history. In comparison to fine-grained sediments which have been extensively studied in the recent past, supralittoral megaclasts are less investigated, essentially due to the difficulties related to the dating of corresponding depositional events, and thus their limited value for inferring the timing of major events. On Bonaire (Leeward Antilles, Caribbean), supratidal coarse-clast deposits form prominent landforms all around the island. Fields of large boulders (up to 150 t) are among the best-studied reef-top megaclasts worldwide. Transport by Holocene tsunamis is assumed at least for the largest boulders (Engel and May, 2012). Although a large dataset of 14C and electron spin resonance (ESR) ages is available for major coral rubble ridges and ramparts, showing some age clusters during the Late Holocene, it is still debated whether these data reflect the timing of major depositional/transport event(s), and how these data sets are biased by reworking of coral fragments. In addition, different processes may be responsible for the deposition of the coral rubble ridges and ramparts (storm) and the solitary megaclasts (tsunami). As an attempt to overcome the current challenges for dating the dislocation of the megaclasts, three distinct dating methods were implemented: (i) 14C dating of boring bivalves (Lithophaga) attached to the boulders; (ii) uranium-series (U/Th) dating of post-depositional, secondary calcitic flowstone at the underside of the boulders; and (iii) surface exposure dating of overturned boulders via 36Cl concentration measurements in corals. The three 14C datings yield age estimates >37 ka, i.e. most probably beyond the applicability of the method, which sheds doubt on the usefulness of this

  8. The Cosmic-Ray Radioactive Nuclide 36Cl and Its Propagation in the Galaxy

    NASA Astrophysics Data System (ADS)

    Connell, J. J.; DuVernois, M. A.; Simpson, J. A.

    1998-12-01

    Radioactive 36Cl has been resolved from 35Cl and 37Cl for the first time in the cosmic radiation with measurements obtained from the high-resolution High-Energy Telescope (HET) carried on the NASA-ESA Ulysses spacecraft. Within the framework of a homogeneous propagation model wherein all 36Cl is of spallation origin, the average density of the interstellar gas ρ, through which all cosmic-ray nuclei propagate, was determined. Heliospheric modulation was included in the analysis. The abundance ratio 36Cl/Cl=5.2+/-1.8% at an average energy of 238 MeV u-1 yields ρ=0.28+0.12-0.10 atoms cm-3. Although 36Cl has a relatively short half-life (τ1/2=3.01×105 yr) compared with the approximately 20 Myr confinement or escape time Tesc for cosmic rays in the Galaxy derived from 10Be or 26Al analysis, it is shown that the confinement time based on 36Cl analysis is 18+10-6 Myr. Radioactive 10Be, 26Al, and 36Cl are all produced by nuclear interactions during propagation from Galactic sources to the observer. However, 10Be, 26Al, and 36Cl are each predominantly products of different primary cosmic-ray nuclei. 54Mn is the fourth radioactive isotope measured by the Ulysses HET. Unfortunately, its decay half-life to 54Fe is difficult to determine. Recent measurements yielded τ1/2=6.3×105 yr, leading to ρ=0.40+0.23-0.15 atoms cm-3 with a confinement time Tesc=11 Myr.

  9. Radiocarbon dating and the 36Cl/Cl evolution of three Great Artesian Basin wells at Dalhousie, South Australia

    NASA Astrophysics Data System (ADS)

    Abu Risha, Usama A.

    2016-06-01

    The use of 14C (half-life = 5,730 years) in modeling the evolution of the 36Cl/Cl ratios in groundwater is reported for the first time. The complexity of the Cl-36Cl system due to the occurrence of different Cl and 36Cl sources and the difficulty of the determination of the initial groundwater 36Cl/Cl ratios have raised concerns about the reliability of using 36Cl (half-life = 301 thousand years, a) as a groundwater-dating tool. This work uses groundwater 14C age as a calibrating parameter of the Cl-36Cl/Cl decay-mixing models of three wells from the southwestern Great Artesian Basin (GAB), Australia. It aims to allow for the different sources of Cl and 36Cl in the southwestern GAB aquifer. The results show that the initial Cl concentrations range from 245 to 320 mg/l and stable Cl is added to groundwater along flowpaths at rates ranging from 1.4 to 3.5 mg/l/ka. The 36Cl content of the groundwater is assumed to be completely of atmospheric origin. The samples have different Cl-36Cl/Cl mixing-decay models reflecting recharge under different conditions as well as the heterogeneity of the aquifer.

  10. Formation of the Short-lived Radionuclide 36Cl in the Protoplanetary Disk During Late-stage Irradiation of a Volatile-rich Reservoir

    NASA Astrophysics Data System (ADS)

    Jacobsen, Benjamin; Matzel, Jennifer; Hutcheon, Ian D.; Krot, Alexander N.; Yin, Qing-Zhu; Nagashima, Kazuhide; Ramon, Erick C.; Weber, Peter K.; Ishii, Hope A.; Ciesla, Fred J.

    2011-04-01

    Short-lived radionuclides (SLRs) in the early solar system provide fundamental insight into protoplanetary disk evolution. We measured the 36Cl-36S-isotope abundance in wadalite (<15 μm), a secondary chlorine-bearing mineral found in calcium-aluminum-rich inclusions (CAIs) in the Allende CV chondrite, to decipher the origin of the SLR 36Cl (τ 1/2 ~ 3 × 105 yr) in the early solar system. Its presence, initial abundance, and the noticeable decoupling from 26Al raise serious questions about the origin of SLRs. The inferred initial 36Cl abundance for wadalite, corresponding to a 36Cl/35Cl ratio of (1.81 ± 0.13) × 10-5, is the highest 36Cl abundance ever reported in any early solar system material. The high level of 36Cl in wadalite and the absence of 26Al (26Al/27Al <= 3.9 × 10-6) in co-existing grossular (1) unequivocally support the production of 36Cl by late-stage solar energetic particle irradiation in the protoplanetary disk and (2) indicates that the production of 36Cl, recorded by wadalite, is unrelated to the origin of 26Al and other SLRs (10Be, 53Mn) recorded by primary minerals of CAIs and chondrules. We infer that 36Cl was largely produced by irradiation of a volatile-rich reservoir in an optically thin protoplanetary disk adjacent to the region in which the CV chondrite parent asteroid accreted while the Sun was a weak T Tauri star. Subsequently, 36Cl accreted into the Allende CV chondrite together with condensed water ices.

  11. FORMATION OF THE SHORT-LIVED RADIONUCLIDE {sup 36}Cl IN THE PROTOPLANETARY DISK DURING LATE-STAGE IRRADIATION OF A VOLATILE-RICH RESERVOIR

    SciTech Connect

    Jacobsen, Benjamin; Yin Qingzhu; Matzel, Jennifer; Hutcheon, Ian D.; Ramon, Erick C.; Weber, Peter K.; Krot, Alexander N.; Nagashima, Kazuhide; Ishii, Hope A.; Ciesla, Fred J.

    2011-04-20

    Short-lived radionuclides (SLRs) in the early solar system provide fundamental insight into protoplanetary disk evolution. We measured the {sup 36}Cl-{sup 36}S-isotope abundance in wadalite (<15 {mu}m), a secondary chlorine-bearing mineral found in calcium-aluminum-rich inclusions (CAIs) in the Allende CV chondrite, to decipher the origin of the SLR {sup 36}Cl ({tau}{sub 1/2} {approx} 3 x 10{sup 5} yr) in the early solar system. Its presence, initial abundance, and the noticeable decoupling from {sup 26}Al raise serious questions about the origin of SLRs. The inferred initial {sup 36}Cl abundance for wadalite, corresponding to a {sup 36}Cl/{sup 35}Cl ratio of (1.81 {+-} 0.13) x 10{sup -5}, is the highest {sup 36}Cl abundance ever reported in any early solar system material. The high level of {sup 36}Cl in wadalite and the absence of {sup 26}Al ({sup 26}Al/{sup 27}Al {<=} 3.9 x 10{sup -6}) in co-existing grossular (1) unequivocally support the production of {sup 36}Cl by late-stage solar energetic particle irradiation in the protoplanetary disk and (2) indicates that the production of {sup 36}Cl, recorded by wadalite, is unrelated to the origin of {sup 26}Al and other SLRs ({sup 10}Be, {sup 53}Mn) recorded by primary minerals of CAIs and chondrules. We infer that {sup 36}Cl was largely produced by irradiation of a volatile-rich reservoir in an optically thin protoplanetary disk adjacent to the region in which the CV chondrite parent asteroid accreted while the Sun was a weak T Tauri star. Subsequently, {sup 36}Cl accreted into the Allende CV chondrite together with condensed water ices.

  12. Aluminum 26, {sup 10}Be, and {sup 36}Cl depth profiles in the Canyon Diablo iron meteorite

    SciTech Connect

    Michlovich, E.S.; Elmore, D.; Vogt, S.; Lipschutz, M.E.; Masarik, J.; Reedy, R.C.

    1994-11-25

    The authors have measured activities of the long-lived cosmogenic radionuclides {sup 26}Al, {sup 10}Be, and {sup 36}Cl in 12 fragments of the iron meteorite Canyon Diablo and have constructed production rate-versus-depth profiles of those radionuclides. Profiles determined using differential particle fluxes calculated with the LAHET code system are in good agreement with {sup 26}Al, {sup 10}Be, and {sup 36}Cl experimental data, but the agreement for {sup 36}Cl was obtained only after neutron-induced cross sections were modified. Profiles calculated with lunar particle fluxes are much lower than experimental Canyon Diablo profiles. The cosmic ray exposure ages of most samples are near 540 m.y. 34 refs., 4 figs., 2 tabs.

  13. Search for extinct 36Cl: Vigarano CAIs, the Pink Angel from Allende, and a Ningqiang chondrule

    NASA Astrophysics Data System (ADS)

    Nakashima, Daisuke; Ott, Ulrich; Hoppe, Peter; El Goresy, Ahmed

    2008-12-01

    We have searched for excesses of 36S derived from the decay of extinct 36Cl in sodalite, a secondary Cl-rich mineral, in Ca-Al-rich inclusions (CAIs) from the Vigarano and Allende CV3 chondrites and in a chondrule from the Ningqiang carbonaceous chondrite. The presence of sodalite in two CAIs from Vigarano and its absence from surrounding CAI fragments suggests sodalite formation after CAI fragmentation. As for sodalite in the Allende Pink Angel CAI, oxygen isotopic compositions have been interpreted as indicative of high temperature interactions, thus suggesting formation prior to accretion to the parent body, probably in a nebular setting. Sodalite in the Ningqiang chondrule is considered to have formed via alkali-Ca exchange, which is believed to have occurred before accretion to the parent body. Sodalites in the Vigarano CAIs and in the Ningqiang chondrule show no clear evidence for the presence of radiogenic 36S. The inferred 2 σ upper limits for 36Cl/ 35Cl at the time of sodalite formation are 1.6 × 10 -6 (Vigarano CAIs) and 3.3 × 10 -6 (Ningqiang chondrule), respectively. In the Pink Angel CAI sodalite exhibits small 36S excesses which weakly correlate with 35Cl/ 34S ratios. The inferred 36Cl/ 35Cl ratio of (1.8 ± 2.2) × 10 -6 (2 σ error) is lower than that found by Hsu et al. [Hsu, W., Guan, Y., Leshin, L. A., Ushikubo, T. and Wasserburg, G. J. (2006) A late episode of irradiation in the early solar system: Evidence from extinct 36Cl and 26Al in meteorites. Astrophys. J. 640, 525-529], thus indicative of heterogeneous distribution of 36Cl in this CAI. Spallation reactions induced by energetic particles from the young Sun are suggested for the origin of 36Cl, similar to the case of 10Be. While 10Be appears to be present in roughly equal abundance in all studied CAIs, our study indicates the level of 36Cl abundances to be variable so that there seems to be no simple relationship between 10Be and 36Cl. This would be expected if trapped cosmic rays rather

  14. Temporal evolution of (36)Cl abundances in the Great Lakes.

    PubMed

    Poghosyan, Armen; Sturchio, Neil C

    2015-06-01

    The observed (36)Cl isotopic abundance in Great Lakes water decreases from west to east, with the highest (36)Cl/Cl ratio of 1332 × 10(-15) in Lake Superior and the lowest (36)Cl/Cl ratio of 151 × 10(-15) in Lake Erie, whereas the (36)Cl concentration ((36)Cl atoms/L) is lowest in Lake Superior and higher in the other Great Lakes. The (36)Cl concentration in Lake Superior is much higher than expected from normal atmospheric deposition over the basin, consistent with deposition of nuclear bomb-produced (36)Cl during 1952-1964. A conservative mass-balance model constrained by hydrological parameters and available (36)Cl fluence measurements predicts the (36)Cl abundances in the Great Lakes from 1945 to 2015, in excellent agreement with available data for Lakes Superior, Michigan, and Huron, but the model underestimates (36)Cl abundances for Lakes Erie and Ontario. However, assuming that (36)Cl demonstrates non-conservative behavior and is significantly retained in the drainage basins, a model incorporating a delayed input parameter successfully predicts observed (36)Cl concentrations in all of the Great Lakes.

  15. Cosmogenic 10Be, 21Ne and 36Cl in sanidine and quartz from Chilean ignimbrites

    NASA Astrophysics Data System (ADS)

    Ivy-Ochs, S.; Kober, F.; Alfimov, V.; Kubik, P. W.; Synal, H.-A.

    2007-06-01

    Our initial results indicate that three cosmogenic nuclides: 10Be, 21Ne and 36Cl can be analyzed in sanidine. To uncover complex exposure histories or marked changes in denudation rates over time several nuclides with different half-lives (or stable) must be measured. Because of its shorter half-life, the combination of 36Cl and a long-lived nuclide 10Be or stable nuclide 21Ne will provide more information than the pairs 10Be and 26Al or 10Be and 21Ne (in quartz). Sanidine (alkali feldspar) is a common high temperature mineral and often dominates the phenocryst assemblage in silicic to intermediate volcanic rocks. Bedrock surfaces studied come from the Oxaya (erupted 19-23 Ma) and Lauca (erupted 2.7 Ma) ignimbrites of northern Chile. Quartz and sanidine phenocrysts coexist; therefore, we can check the viability of sanidine through direct comparison with nuclide concentrations in quartz. In addition, as quartz has no target for 36Cl in significant abundance we show that the unique power of sanidine is that 36Cl can be measured. We have obtained very good agreement between 10Be and 21Ne concentrations measured in sanidine and coexisting quartz. No meteoric 10Be was apparent in these sanidines. Concentrations of all three nuclides in mineral separates from rock sample CN309 from the Lauca ignimbrite in the Western Cordillera agree well and correspond to minimum exposure ages of 30-50 ka. 10Be and 21Ne measured in both sanidine and quartz from three rock samples from the Oxaya ignimbrite (CN19, CN23, CN104a) in the Western Escarpment record low average landscape modification rates (<0.70 m/Ma) over the last several million years. In contrast, 36Cl data from sanidine in CN23 seem to indicate shorter minimum exposures and more rapid maximum erosion rates.

  16. Infiltration at yucca mountain, nevada, traced by 36Cl

    NASA Astrophysics Data System (ADS)

    Norris, A. E.; Wolfsberg, K.; Gifford, S. K.; Bentley, H. W.; Elmore, D.

    1987-11-01

    Measurements of chloride and 36Cl in soils from two locations near Yucca Mountain, Nevada, have been used to trace the infiltration of precipitation in this arid region. The results show that the 36Cl fallout from nuclear-weapons testing formed a well-defined peak at one location, with a maximum 36Cl/Cl ratio 0.5 m below the surface. The structure of the 36Cl bomb pulse at the other location was much more complex, and the quantity of 36Cl in the bomb pulse was < 1% of the 6 × 10 12 atoms {36Cl }/{m 2} in the bomb pulse at the first location. The data indicate hydrologic activity subsequent to the 36Cl bomb-pulse fallout at one location, but none at the other location.

  17. Medical application of 26Al

    NASA Astrophysics Data System (ADS)

    Steinhausen, C.; Gerisch, P.; Heisinger, B.; Hohl, Ch.; Kislinger, G.; Korschinek, G.; Niedermayer, M.; Nolte, E.; Dumitru, M.; Alvarez-Brückmann, M.; Schneider, M.; Ittel, T. H.

    1996-06-01

    Accelerator mass spectrometry (AMS) measurements with 26Al as tracer were performed in order to study the aluminium metabolism and anomalies in the human body and in rats. In particular, the differences between healthy volunteers and patients with renal failure were investigated. The obtained data points of 26Al in blood and urine were described by an open compartment model with three peripheral compartments. It was found that the minimum of peripheral compartments needed to describe 26Al concentrations in blood and urine over a time period of three years is at least three.

  18. Infiltration at Yucca Mountain, Nevada, traced by {sup 36}Cl

    SciTech Connect

    Norris, A.E.; Wolfsberg, K.; Gifford, S.K.; Bentley, H.W.; Elmore, D.

    1987-04-01

    Measurements of chloride and {sup 36}Cl in soils from two locations near Yucca Mountain, Nevada, have been used to trace the infiltration of precipitation in this arid region. The results show that the {sup 36}Cl fallout from nuclear weapons testing formed a well-defined peak at one location, with a maximum 0.5m below the surface. The structure of the {sup 36}Cl bomb pulse at the other location was much more complex, and quantity of {sup 36}Cl in the bomb pulse was <1% of the 6 x 10{sup 12} atoms {sup 36}Cl/m{sup 2} in the bomb pulse at the first location. The data indicate hydrologic activity subsequent to the {sup 36}Cl bomb pulse fallout at one location, but none at the other location. 11 refs.

  19. Detection of 36Cl with accelerator mass spectrometry

    NASA Astrophysics Data System (ADS)

    Jiang, Songsheng; Ma, Tiejung; Jiang, Shan; Yang, Bingfan; Wang, Xun; Huang, Qi

    1989-12-01

    An accelerator mass spectrometry (AMS) system based on the HI-13 tandem accelerator at the Institute of Atomic Energy (IAE) is described, and the first detection of 36Cl with our AMS system is reported. The electrostatic deflector completely rejects isotopic background, 35Cl and 37Cl. The ioinzation chamber distinguishs 36Cl from isobaric background, 36S. The measurement of 36Cl with two samples is presented.

  20. {sup 36}Cl bomb fallout at mid latitudes

    SciTech Connect

    Synal, H.A.; Beer, J.; Gaeggeler, H.

    1995-12-01

    Large amounts of {sup 36}Cl have been produced during the atmospheric test of nuclear weapons in the late fifties and early sixties. During this time the {sup 36}Cl fallout was about three orders of magnitudes larger than during previous times. The well defined {sup 36}Cl pulse has a great potential for hydrological investigations, especially as a tracer for groundwater studies. Detailed measurements of bomb produced {sup 36}Cl were carried out earlier on ice cores from Dye-3 (Greenland). To adopt the {sup 36}Cl pulse measured in Greenland as an input function to other locations its latitude dependence has to be known. So far, atmospheric transport models and the measured distribution of {sup 90}Sr and {sup 137}Cs fallout are used to estimate the latitude dependence of meteoric and bomb produced {sup 36}Cl fallout. In this contribution, {sup 36}Cl measurements on an ice core from an Alpine Glacier (Fiescher Horn, Switzerland) are presented. The results are compared with earlier measurements from a Greenland ice core and implications for the global {sup 36}Cl transport are discussed.

  1. Atmospheric transport of bomb-produced 36Cl

    NASA Astrophysics Data System (ADS)

    Synal, H.-A.; Beer, J.; Bonani, G.; Suter, M.; Wölfli, W.

    1990-12-01

    36Cl measurements have been made in an arctic ice core drilled near the Dye-3 site (65°11'N, 43°50'W). The samples analyzed cover the period between 1945 and 1985 with annual resolution. Due to the release of 36Cl to the atmosphere from nuclear bomb tests, the data shown a peak in the late fifties with 36Cl fallout rates about three orders of magnitude higher than expected from cosmic ray production. The time resolution is now precise enough to resolve the structure of the descending part of the fallout pattern. From the fallout rates obtained, a stratospheric residence time for bomb-produced 36Cl could be derived. A detailed interpretation of the data is done with a four-box atmospheric transport model. The large and well-defined 36Cl bomb pulse provides an excellent tracer for ground water studies.

  2. Determination of 36Cl in nuclear waste from reactor decommissioning.

    PubMed

    Hou, Xiaolin; Ostergaard, Lars Frøsig; Nielsen, Sven P

    2007-04-15

    An analytical method for the determination of 36Cl in nuclear waste such as graphite, heavy concrete, steel, aluminum, and lead was developed. Several methods were investigated for decomposing the samples. AgCl precipitation was used to separate 36Cl from the matrix elements, followed by ion-exchange chromatography to remove interfering radionuclides. The purified 36Cl was then measured by liquid scintillation counting. The chemical yield of chlorine, as measured by ICPMS, is above 70% and the decontamination factors for all interfering radionuclides are greater than 10(6). The detection limit of this analytical method for 36Cl is 14 mBq. The method has been used to determine 36Cl in heavy concrete, aluminum, and graphite from the Danish DR-2 research reactor.

  3. Determination of 36Cl in nuclear waste from reactor decommissioning.

    PubMed

    Hou, Xiaolin; Ostergaard, Lars Frøsig; Nielsen, Sven P

    2007-04-15

    An analytical method for the determination of 36Cl in nuclear waste such as graphite, heavy concrete, steel, aluminum, and lead was developed. Several methods were investigated for decomposing the samples. AgCl precipitation was used to separate 36Cl from the matrix elements, followed by ion-exchange chromatography to remove interfering radionuclides. The purified 36Cl was then measured by liquid scintillation counting. The chemical yield of chlorine, as measured by ICPMS, is above 70% and the decontamination factors for all interfering radionuclides are greater than 10(6). The detection limit of this analytical method for 36Cl is 14 mBq. The method has been used to determine 36Cl in heavy concrete, aluminum, and graphite from the Danish DR-2 research reactor. PMID:17375901

  4. High (36)Cl/Cl ratios in Chernobyl groundwater.

    PubMed

    Roux, Céline; Le Gal La Salle, Corinne; Simonucci, Caroline; Van Meir, Nathalie; Fifield, L Keith; Diez, Olivier; Bassot, Sylvain; Simler, Roland; Bugai, Dmitri; Kashparov, Valery; Lancelot, Joël

    2014-12-01

    After the explosion of the Chernobyl Nuclear Power Plant in April 1986, contaminated material was buried in shallow trenches within the exclusion zone. A (90)Sr plume was evidenced downgradient of one of these trenches, trench T22. Due to its conservative properties, (36)Cl is investigated here as a potential tracer to determine the maximal extent of the contamination plume from the trench in groundwater. (36)Cl/Cl ratios measured in groundwater, trench soil water and leaf leachates are 1-5 orders of magnitude higher than the theoretical natural (36)Cl/Cl ratio. This contamination occurred after the Chernobyl explosion and currently persists. Trench T22 acts as an obvious modern point source of (36)Cl, however other sources have to be involved to explain such contamination. (36)Cl contamination of groundwater can be explained by dilution of trench soil water by uncontaminated water (rainwater or deep groundwater). With a plume extending further than that of (90)Sr, radionuclide which is impacted by retention and decay processes, (36)Cl can be considered as a suitable tracer of contamination from the trench in groundwater provided that modern release processes of (36)Cl from trench soil are better characterized. PMID:25128774

  5. High (36)Cl/Cl ratios in Chernobyl groundwater.

    PubMed

    Roux, Céline; Le Gal La Salle, Corinne; Simonucci, Caroline; Van Meir, Nathalie; Fifield, L Keith; Diez, Olivier; Bassot, Sylvain; Simler, Roland; Bugai, Dmitri; Kashparov, Valery; Lancelot, Joël

    2014-12-01

    After the explosion of the Chernobyl Nuclear Power Plant in April 1986, contaminated material was buried in shallow trenches within the exclusion zone. A (90)Sr plume was evidenced downgradient of one of these trenches, trench T22. Due to its conservative properties, (36)Cl is investigated here as a potential tracer to determine the maximal extent of the contamination plume from the trench in groundwater. (36)Cl/Cl ratios measured in groundwater, trench soil water and leaf leachates are 1-5 orders of magnitude higher than the theoretical natural (36)Cl/Cl ratio. This contamination occurred after the Chernobyl explosion and currently persists. Trench T22 acts as an obvious modern point source of (36)Cl, however other sources have to be involved to explain such contamination. (36)Cl contamination of groundwater can be explained by dilution of trench soil water by uncontaminated water (rainwater or deep groundwater). With a plume extending further than that of (90)Sr, radionuclide which is impacted by retention and decay processes, (36)Cl can be considered as a suitable tracer of contamination from the trench in groundwater provided that modern release processes of (36)Cl from trench soil are better characterized.

  6. Distribution and Origin of 36Cl In Allende CAIs

    SciTech Connect

    Matzel, J P; Jacobsen, B; Hutcheon, I D; Krot, A N; Nagashima, K; Yin, Q; Ramon, E C; Weber, P; Wasserburg, G J

    2009-12-11

    The abundance of short-lived radionuclides (SLRs) in early solar system materials provide key information about their nucleosynthetic origin and can constrain the timing of early solar system events. Excesses of {sup 36}S ({sup 36}S*) correlated with {sup 35}Cl/{sup 34}S ratios provide direct evidence for in situ decay of {sup 36}Cl ({tau}{sub 1/2} {approx} 0.3 Ma) and have been reported in sodalite (Na{sub 8}Al{sub 6}Si{sub 6}O{sub 24}Cl{sub 2}) and wadalite (Ca{sub 6}Al{sub 5}Si{sub 2}O{sub 16}Cl{sub 3}) in CAIs and chondrules from the Allende and Ningqiang CV carbonaceous chondrites. While previous studies demonstrate unequivocally that {sup 36}Cl was extant in the early solar system, no consensus on the origin or initial abundance of {sup 36}Cl has emerged. Understanding the origin of {sup 36}Cl, as well as the reported variation in the initial {sup 36}Cl/{sup 35}Cl ratio, requires addressing when, where and how chlorine was incorporated into CAIs and chondrules. These factors are key to distinguishing between stellar nucleosynthesis or energetic particle irradiation for the origin of {sup 36}Cl. Wadalite is a chlorine-rich secondary mineral with structural and chemical affinities to grossular. The high chlorine ({approx}12 wt%) and very low sulfur content (<<0.01 wt%) make wadalite ideal for studies of the {sup 36}Cl-{sup 36}S system. Wadalite is present in Allende CAIs exclusively in the interior regions either in veins crosscutting melilite or in zones between melilite and anorthite associated with intergrowths of grossular, monticellite, and wollastonite. Wadalite and sodalite most likely resulted from open-system alteration of primary minerals with a chlorine-rich fluid phase. We recently reported large {sup 36}S* correlated with {sup 35}Cl/{sup 34}S in wadalite in Allende Type B CAI AJEF, yielding a ({sup 36}Cl/{sup 35}Cl){sub 0} ratio of (1.7 {+-} 0.3) x 10{sup -5}. This value is the highest reported {sup 36}Cl/{sup 35}Cl ratio and is {approx}5 times

  7. Measurement campaign for astrophysically relevant 36Cl production cross sections

    NASA Astrophysics Data System (ADS)

    Anderson, Tyler; Skulski, Michael; Ostdiek, Karen; Lu, Wenting; Beard, Mary; Collon, Philippe

    2015-10-01

    The short-lived radionuclide 36Cl (t1/2 = 0.301 Ma) is known to have existed in the Early Solar System (ESS), and evaluating its production sources can lead to better understanding of the processes taking place in ESS formation and their timescales. The x-wind production model is used to explain 36Cl production via solar energetic particles from the young Sun, but is lacking empirical data for many relevant reactions. Bowers et al. (2013) measured the cross section of 33S(α,p)36Cl at various energies in the range of 0.70-2.42 MeV/A, and found them to be systematically under predicted by statistical Hauser-Feshbach model codes TALYS and NON-SMOKER, highlighting the need for more empirical data for these cross sections. A recent paper by Mohr (2013) called these results in to question, prompting the re-measurement of the cross section for 33S(α,p)36Cl at new energies in the same energy range as Bowers et al. This talk will also discuss two further planned measurements of cross sections suggested by Bowers et al. to be the next most significant in 36Cl production.

  8. Survey on Cosmogenic 26Al in Lewis Cliff Meteorites

    NASA Astrophysics Data System (ADS)

    Welten, K. C.; Alderliesten, C.; Lindner, L.

    1992-07-01

    levels of 56 +- 7 and 60 +- 7 for H and L chondrites, respectively [3], range up to 800 ka with an average of about 290 ka. Altogether this may indicate that the Lewis Cliff blue-ice region is a relatively old meteorite stranding area. This is supported by preliminary conclusions based on ^36Cl, measured in 8 Lewis Cliff meteorites [4]. However, it is likely that some of our terrestrial ages have been overestimated due to (i) lower ^26Al saturation values for meteorites with preatmospheric radii less than 20 cm [3] and (ii) low exposure ages, resulting in initial ^26Al levels below 90-95% of the saturation level. These effects make individual terrestrial age determinations solely based on ^26Al content speculative as long as additional cosmogenic nuclide data are lacking. Dramatic changes in the overall picture are not expected, because (i) we have measured relatively large samples with an average recovered weight of about 500 g (one 11-kg sample excluded) and (ii) anomalously low exposure ages occur in about only 5% of the cases [5,6]. Possible correlations between terrestrial age and place of find will be discussed. UNUSUAL EXPOSURE HISTORIES: We excluded samples with extremely low NTL (<1 krad) from the above discussion, because these may have been exposed to high SCR-fluxes due to smallperihelia orbits (<0.7 A.U.) [7]. This hypothesis is supported by LEW 87169 and 87143, which have extremely low NTL-values in combination with high ^26Al contents. PAIRING CRITERIA: In order to impose additional constraints on pairing possibilities we critically used--besides classification, location of find and TL-properties--the cosmogenic ^26Al and also the natural ^40K content of ordinary chondrites. As an example we will show that the 15 measured Lewis Cliff L6 chondrites are representing at least 10 separate falls. Acknowledgements. This work was performed with financial support from the "Nederlandse Organisatie voor Wetenschappelijk Onderzoek" (NWO). References: 1. Komura K. et

  9. Survey on Cosmogenic 26Al in Lewis Cliff Meteorites

    NASA Astrophysics Data System (ADS)

    Welten, K. C.; Alderliesten, C.; Lindner, L.

    1992-07-01

    levels of 56 +- 7 and 60 +- 7 for H and L chondrites, respectively [3], range up to 800 ka with an average of about 290 ka. Altogether this may indicate that the Lewis Cliff blue-ice region is a relatively old meteorite stranding area. This is supported by preliminary conclusions based on ^36Cl, measured in 8 Lewis Cliff meteorites [4]. However, it is likely that some of our terrestrial ages have been overestimated due to (i) lower ^26Al saturation values for meteorites with preatmospheric radii less than 20 cm [3] and (ii) low exposure ages, resulting in initial ^26Al levels below 90-95% of the saturation level. These effects make individual terrestrial age determinations solely based on ^26Al content speculative as long as additional cosmogenic nuclide data are lacking. Dramatic changes in the overall picture are not expected, because (i) we have measured relatively large samples with an average recovered weight of about 500 g (one 11-kg sample excluded) and (ii) anomalously low exposure ages occur in about only 5% of the cases [5,6]. Possible correlations between terrestrial age and place of find will be discussed. UNUSUAL EXPOSURE HISTORIES: We excluded samples with extremely low NTL (<1 krad) from the above discussion, because these may have been exposed to high SCR-fluxes due to smallperihelia orbits (<0.7 A.U.) [7]. This hypothesis is supported by LEW 87169 and 87143, which have extremely low NTL-values in combination with high ^26Al contents. PAIRING CRITERIA: In order to impose additional constraints on pairing possibilities we critically used--besides classification, location of find and TL-properties--the cosmogenic ^26Al and also the natural ^40K content of ordinary chondrites. As an example we will show that the 15 measured Lewis Cliff L6 chondrites are representing at least 10 separate falls. Acknowledgements. This work was performed with financial support from the "Nederlandse Organisatie voor Wetenschappelijk Onderzoek" (NWO). References: 1. Komura K. et

  10. 36Cl-36Ar Exposure Ages of Chondritic Metals

    NASA Astrophysics Data System (ADS)

    Graf, Th.; Caffee, M. W.; Finkel, R. C.; Marti, K.; Nishiizumi, K.; Ponganis, K. V.

    1995-09-01

    Metal separates were prepared to determine ^36Cl-^36Ar exposure ages for six H4 p.m. falls (with reported bulk exposure ages of 4 to 10Ma), for ten H5 a.m. falls (T(sub)e = 4-10 Ma) and for the Acapulco meteorite (T(^36Cl-^36Ar)= 5.7 Ma). This dating method uses production rate ratios P(^36Cl)/P(^36Ar) and is independent of the shielding-sensitive absolute production rates. It is also known that for protons the production rate ratio is rather insensitive to changes in the energy spectrum; the dependence of this ratio for secondary neutrons is at present less understood. First results were already reported [1]. The cosmic-ray-produced ^3He/^38Ar ratios show a bimodal distribution with two clusters at about 15 and about 9 (Fig. 1). About half of the ^3He is produced via ^3H which is known to diffuse in metal at relatively low temperatures. Therefore, Fig. 1 provides evidence for a quasi-continuous loss of ^3H from such metals. If this loss mechanism is due to solar heating, perihelia <1 AU are indicated for these meteorites. Losses are prominent for H5 a.m. falls, but not for H4 p.m. falls. The orbital implications are consistent with those already known from the time-of-fall parameter (p.m. falls / total falls) which was used in the selection of the H4,H5 sample sets [2]. The exposure age histograms of both H groups show the well known clusters at about 7 Ma. The width of the exposure age peaks differ, however, and the collisional break-up event can be further constrained. Except for Nassirah, all members of the H4 p.m. group fall into the range 7.0 +/- 0.3 Ma. Bulk rock ages (8.2-9.3 Ma) [3] as well as the ^36Cl-^36Ar age (8.3 Ma) of Nassirah are higher and may indicate that this meteorite does not belong to the collisional event. We observe a small but systematic difference in calculated exposure ages by the ^36Cl-^36Ar method, when compared with ages obtained by conventional noble gas production rates. This shift (about 10%) does not appear to be dependent on

  11. Extracting in situ cosmogenic 14C from olivine: significance for the CRONUS-Earth project

    NASA Astrophysics Data System (ADS)

    Pigati, J. S.; Lifton, N. A.; Quade, J.; Jull, A. T.

    2005-12-01

    One of the main goals of the Cosmic-Ray-prOduced NUclide Systematics on Earth (CRONUS-Earth) project is to compare production rates of in situ cosmogenic nuclides (CNs) at several well-dated locations in various rock types. Quartz is the most commonly used target mineral for several CNs (e.g., 10Be, 26Al, 21Ne, 14C), but is generally absent in mafic volcanic terrains, where flows of different ages can constrain temporal variations in CN production at a given location. Because of its short half-life (5.73 ka), in situ cosmogenic 14C (in situ 14C) can be particularly useful for elucidating temporal variations in CN production over much shorter time scales than other CNs. While CNs such as 36Cl and 21Ne can be measured in both mafic and felsic rocks, clearly it would be advantageous to measure in situ 14C in mafic rocks as well. As such, we have worked to develop reliable protocols to extract in situ 14C from olivine. We conducted numerous stepped combustion experiments testing the efficacy of various chemical pretreatments. We were able to extract a stable and reproducible in situ 14C component from olivine using a LiBO2 flux, following pretreatment with dilute HNO3. However, measured concentrations in olivine (normalized to SiO2 composition) from two known-age basalt flows, the Tabernacle Hill flow (17.3+/-0.4 ka in age) in central Utah and the McCarty's flow (3.0+/-0.2 ka in age) in western New Mexico, were 3 to 5 times lower than predicted in situ 14C concentrations based on measurements in quartz. This discrepancy appears to arise from (1) a synthetic spinel-like mineral formed during our extraction process by the chemical interaction of the Al2O3 sample boat and olivine dissolved within the LiBO2 flux, and (2) undissolved pyroxene phenocrysts (difficult to separate in quantity from olivines). Although we do not fully understand how the formation of the synthetic mineral may affect carbon atoms liberated from olivine, the concentration of in situ 14C atoms that

  12. SPI measurements of Galactic 26Al

    NASA Astrophysics Data System (ADS)

    Diehl, R.; Knödlseder, J.; Lichti, G. G.; Kretschmer, K.; Schanne, S.; Schönfelder, V.; Strong, A. W.; von Kienlin, A.; Weidenspointner, G.; Winkler, C.; Wunderer, C.

    2003-11-01

    The precision measurement of the 1809 keV gamma-ray line from Galactic 26Al is one of the goals of the SPI spectrometer on INTEGRAL with its Ge detector camera. We aim for determination of the detailed shape of this gamma-ray line, and its variation for different source regions along the plane of the Galaxy. Data from the first part of the core program observations of the first mission year have been inspected. A clear detection of the 26Al line at =~ 5-7 sigma significance demonstrates that SPI will deepen 26Al studies. The line intensity is consistent with expectations from previous experiments, and the line appears narrower than the 5.4 keV FWHM reported by GRIS, more consistent with RHESSI's recent value. Only preliminary statements can be made at this time, however, due to the multi-component background underlying the signal at =~ 40 times higher intensity than the signal from Galactic 26Al.

  13. {sup 36}Cl studies of water movements deep within unsaturated tuffs

    SciTech Connect

    Norris, A.E.; Bentley, H.W.; Cheng, S.; Kubik, P.W.; Sharma, P.; Gove, H.E.

    1990-05-01

    Measurements of {sup 36}Cl in cuttings from a borehole that was drilled 387 m into unsaturated tuffs indicate the possible detection of significant radioactive decay of cosmogenic {sup 36}Cl in two of the samples. However, the {sup 36}Cl/Cl ratio was found to vary with the amount of pulverization of the cuttings. Work is in progress to separate the {sup 36}Cl/Cl data into cosmogenic and in situ components. The cosmogenic component will be used to trace very slow water movements through the unsaturated zone. Bomb pulse {sup 36}Cl was observed as deep as 153 m, and this identification is not constrained by the problem with pulverization. This work shows the efficacy of {sup 36}Cl measurements for detecting modern water movements deep in the unsaturated zone. 9 refs., 3 tabs.

  14. Observable Proxies For 26 Al Enhancement

    SciTech Connect

    Fryer, Christopher L; Young, Patrick A; Ellinger, Carola I; Arnett, William D

    2008-01-01

    We consider the cospatial production of elements in supernova explosions to find observationally detectable proxies for enhancement of {sup 26}Al in supernova ejecta and stellar systems. Using four progenitors we explore a range of 1D explosions at different energies and an asymmetric 3D explosion. We find that the most reliable indicator of the presence of {sup 26}Al in unmixed ejecta is a very low S/Si ratio ({approx} 0.05). Production of N in O/S/Si-rich regions is also indicative. The biologically important element P is produced at its highest abundance in the same regions. Proxies should be detectable in supernova ejecta with high spatial resolution multi wavelength observations, but the small absolute abundance of material injected into a proto-planetary disk makes detection unlikely in existing or forming stellar/planetary systems.

  15. Evidence that 26Al Did Not Melt Asteroids

    NASA Astrophysics Data System (ADS)

    Wasson, J. T.

    2016-08-01

    26Al/27Al initial ratios in achondrites are much lower than expected if 26Al was the only heat source responsible for melting the parental materials. Impacts provided a substantial fraction of the heat.

  16. The French accelerator mass spectrometry facility ASTER after 4 years: Status and recent developments on 36Cl and 129I

    NASA Astrophysics Data System (ADS)

    Arnold, Maurice; Aumaître, Georges; Bourlès, Didier L.; Keddadouche, Karim; Braucher, Régis; Finkel, Robert C.; Nottoli, Emmanuelle; Benedetti, Lucilla; Merchel, Silke

    2013-01-01

    Since the acceptance tests of the French 5 MV accelerator mass spectrometry facility ASTER in 2007, routine measurement conditions for the long-lived radionuclides 10Be and 26Al have been established. Yearly sample throughput as high as over 3300 unknowns has been reached for 10Be in 2010. Cross-contamination for volatile elements has been largely solved by an ion source upgrade allowing 36Cl measurements at ASTER. However, recent long-term tests using 35Cl/37Cl samples with strongly varying ratios have shown that identical targets lead to different 35Cl/37Cl results at the 2-4% level when being measured after a time gap of 24 h while the source is running other samples. Besides time dependent mass fractionation, another likely reason for this effect might be source memory, thus, asking for sophisticated measurement strategies and improved data evaluation and eventually further ion source improvement. Finally, after establishing quality assurance by cross-calibration of secondary in-house 26Al and 41Ca standards and taking part in round-robin exercises of 10Be and 36Cl, a two-step cross-calibration of secondary in-house 129I standards has been performed. The NIST 3231 standard containing 129I/127I at (0.981 ± 0.012) × 10-6 has been used for step-wise dilution with NaI to produce gram-quantities of lower-level standards for every-day use. The resulting material SM-I-9 (129I/127I: ∼1 × 10-9) has been measured vs. AgI produced using minimum chemistry from the two NIST ampoules containing a solution with a nominal ratio 129I/127I of (0.982 ± 0.012) × 10-8. In a second stage, SM-I-10 and SM-I-11 with ratios of ∼1 × 10-10 and ∼1 × 10-11, respectively, have been cross-calibrated against SM-I-9. Individual uncertainties of the traceable secondary standards are 1.3-1.4% (2σ), mainly originating from the given uncertainty of the primary NIST 3231 at the 10-8 level. The cross-contamination for iodine is in the range of 0.4-0.6% within the first 20 h of running

  17. Determination of 36Cl in biological shield concrete using pyrohydrolysis and liquid scintillation counting.

    PubMed

    Itoh, Mitsuo; Watanabe, Kazuo; Hatakeyama, Mutsuo; Tachibana, Mitsuo

    2002-07-01

    A method for the determination of 36Cl in biological shield concrete of nuclear reactors was developed. Cl in the concrete sample was extracted quantitatively by pyrohydrolysis at 900 degrees C and recovered in Na2CO3 solution for subsequent measurement of 36Cl by liquid scintillation counting. WO3 was used as an accelerator in the pyrohydrolysis. The Cl extraction procedure was optimized by investigating experimental conditions with the use of ion chromatography and its recovery was evaluated by the analysis of the geochemical reference samples. The detection limit of 36Cl was 0.02 Bq g(-1) for a sample weight of 2 g. The relative standard deviation was 3-7% for the samples containing 0.5 Bq g(-1) levels of 36Cl. The method was applied to determine 36Cl in biological shield concrete of the Japan Power Demonstration Reactor. PMID:12173658

  18. The Hiroshima thermal-neutron discrepancy for (36)Cl at large distances. Part I: New (36)Cl measurements in granite samples exposed to A-bomb neutrons.

    PubMed

    Huber, Thomas; Rühm, Werner; Kato, Kazuo; Egbert, Stephen D; Kubo, Florian; Lazarev, Vitali; Nolte, Eckehart

    2005-10-01

    The long-lived radioisotope (36)Cl (half-life: 301,000 years) was measured in granite samples exposed to A-bomb neutrons at distances from 94 to 1,591 m from the hypocenter in Hiroshima, by means of accelerator mass spectrometry (AMS). Measured (36)Cl/Cl ratios decrease from 1.6 x 10(-10) close to the hypocenter to about 1-2 x 10(-13), at a distance of 1,300 m from the hypocenter. At this distance and beyond the measured (36)Cl/Cl ratios do not change significantly and scatter around values of 1-2 x 10(-13). These findings suggest that the (36)Cl had been predominantly produced by thermalized neutrons from the A-bomb via neutron capture on stable (35)Cl, at distances from the hypocenter smaller than about 1,200 m. At larger distances, however, confounding processes induced by cosmic rays or neutrons from the decay of uranium and thorium become important. This hypothesis is theoretically and experimentally supported in a consecutive paper. The results are compared to calculations that are based on the most recent dosimetry system DS02. Close to the hypocenter, measured (36)Cl/Cl ratios are lower than those calculated, while they are significantly higher at large distances from the hypocenter. If the contribution of the cosmic rays and of the neutrons from the decay of uranium and thorium in the sample was subtracted, however, no significant deviation from the DS02 calculations was observed, at those distances. Thus, the Hiroshima neutron discrepancy reported in the literature for (36)Cl for samples from large distances from the hypocenter, i.e., higher measured (36)Cl/Cl ratios than predicted by the previous dosimetry system DS86, was not confirmed.

  19. The distribution of meteoric 36Cl/Cl in the United States: A comparison of models

    USGS Publications Warehouse

    Moysey, S.; Davis, S.N.; Zreda, M.; Cecil, L.D.

    2003-01-01

    The natural distribution of 36Cl/Cl in groundwater across the continental United States has recently been reported by Davis et al. (2003). In this paper, the large-scale processes and atmospheric sources of 36Cl and chloride responsible for controlling the observed 36Cl/Cl distribution are discussed. The dominant process that affects 36Cl/Cl in meteoric groundwater at the continental scale is the fallout of stable chloride from the atmosphere, which is mainly derived from oceanic sources. Atmospheric circulation transports marine chloride to the continental interior, where distance from the coast, topography, and wind patterns define the chloride distribution. The only major deviation from this pattern is observed in northern Utah and southern Idaho where it is inferred that a continental source of chloride exists in the Bonneville Salt Flats, Utah. In contrast to previous studies, the atmospheric flux of 36Cl to the land surface was found to be approximately constant over the United States, without a strong correlation between local 36Cl fallout and annual precipitation. However, the correlation between these variables was significantly improved (R 2=0.15 to R 2=0.55) when data from the southeastern USA, which presumably have lower than average atmospheric 36Cl concentrations, were excluded. The total mean flux of 36Cl over the continental United States and total global mean flux of 36Cl are calculated to be 30.5??7.0 and 19.6??4.5 atoms m-2 s-1, respectively. The 36Cl/Cl distribution calculated by Bentley et al. (1996) underestimates the magnitude and variability observed for the measured 36Cl/Cl distribution across the continental United States. The model proposed by Hainsworth (1994) provides the best overall fit to the observed 36Cl/Cl distribution in this study. A process-oriented model by Phillips (2000) generally overestimates 36Cl/Cl in most parts of the country and has several significant local departures from the empirical data.

  20. High temperature pyrolysis to extract 36Cl for Accelerator Mass Spectrometry measurements

    NASA Astrophysics Data System (ADS)

    Cornett, R. J.; Andrews, H. R.; Chant, L.; Chaput, T.; Imahori, Y.; Jirovec, J.; Kramer, S.; Koslowsky, V. T.; Milton, G. M.; Milton, J. C. D.

    1996-10-01

    36Cl and stable Cl were extracted from solids by high temperature pyrolysis and then analyzed by Accelerator Mass Spectrometry (AMS). Cl was quantitatively extracted from rock, ore, vegetation and freshwater sediments in samples weighing from 100 mg to 2 g. 36Cl:Cl activity ratios measured following Cl extraction by pyrolysis agreed with those measured following Cl extraction by acid leaching. The simple pyrolysis extraction has the additional advantages that stable Cl - can be measured on the same sample along with other anions, the 36Cl:Cl ratio can be adjusted by diluting the known Cl - concentration in the collection solution to control the activity of 36Cl in the target and the potential interference of 36S can also be assessed prior to the AMS measurements.

  1. 26Al uptake and accumulation in the rat brain

    NASA Astrophysics Data System (ADS)

    Yumoto, S.; Nagai, H.; Imamura, M.; Matsuzaki, H.; Hayashi, K.; Masuda, A.; Kumazawa, H.; Ohashi, H.; Kobayashi, K.

    1997-03-01

    To investigate the cause of Alzheimer's disease (senile dementia), 26Al incorporation in the rat brain was studied by accelerator mass spectrometry (AMS). When 26Al was injected into healthy rats, a considerable amount of 26Al entered the brain (cerebrum) through the blood-brain barrier 5 days after a single injection, and the brain 26Al level remained almost constant from 5 to 270 days. On the other hand, the level of 26Al in the blood decreased remarkably 75 days after injection. Approximately 89% of the 26Al taken in by the brain cell nuclei bound to chromatin. This study supports the theory that Alzheimer's disease is caused by irreversible accumulation of aluminium (Al) in the brain, and brain cell nuclei.

  2. Cosmogenic {sup 36}Cl accumulation in unstable landforms 2. Simulations and measurements on eroding moraines

    SciTech Connect

    Zreda, M.G.; Phillips, F.M.; Elmore, D.

    1994-11-01

    Cosmogenic {sup 36}Cl ages of boulders from late Pleistocene moraines in Bishop Creek, Sierra Nevada, California, provided valuable details about {sup 36}Cl surface exposure dating and the nature of post depositional processes that modify glacial landforms. The natural variability of the apparent {sup 36}Cl ages among morainal boulders is due to soil erosion and gradual exposure of boulders at the surface. Two mechanisms are responsible for the resulting distributions of the apparent {sup 36}Cl ages. Variability of the initial burial depth among boulders and variability in the chemical composition of boulders from the same depth both result in different {sup 36}Cl ages due to the dependence of the depth production profile on the boulder chemistry. The authors measured cosmogenic {sup 36}Cl in boulders from a late Pleistocene moraine. The distribution of the calculated apparent ages allowed them to calculate the true age of 85 kyr and the erosion rate of 570 g cm{sup -2}. These results are in excellent agreement with independently estimated values of 87 kyr and 600 g cm{sup -2} for the age and erosion depth, respectively. These results indicate that the model satisfactorily simulates effects of erosion processes and can thus aid in surface exposure dating of eroding landforms.

  3. Comparison of 36Cl and 3He measurements in glacial surfaces on the tropical Altiplano (Cerro Tunupa volcano, 20°S)

    NASA Astrophysics Data System (ADS)

    Schimmelpfennig, Irene; Blard, Pierre-Henri; Lavé, Jérôme; Benedetti, Lucilla; Aster Team

    2016-04-01

    The combination of two or more cosmogenic nuclides measured in the same rock samples allow complex landscape exposure histories to be quantified, due to the nuclide-specific production and decay rates. In supposedly simple exposure scenarios, such as moraine chronologies, the use of more than one nuclide can also help identify outliers caused by geomorphological bias (e.g. "inheritance") or analytical problems (e.g. nuclide loss or contamination during chemical extraction). The two cosmogenic in situ nuclides 3He and 36Cl are potentially very useful to be simultaneously measured in quartz-lacking lithologies, but their application is more challenging than that of combined 10Be and 26Al measurements, which are routinely employed in quartz-bearing rocks. This is, amongst other things, because the production of 3He and 36Cl depend on various compositional factors. Therefore, 3He and 36Cl have rarely been measured in the same samples so far. Here, we present 36Cl measurements in plagioclases extracted from four moraine boulders and one roche moutonnée on the southern flank of Cerro Tunupa volcano, located in the tropical Bolivian Andes (3800-4500 m, 20°S). In pyroxenes of these samples, 3He has previously been measured to gain insights into the local deglaciation history and climate conditions about 15 kyr ago during the Lake Tauca highstand (Blard et al., 2009, 2013). The ages calculated from the measured 3He and 36Cl concentrations of the 5 samples range from 12 kyr to 180 kyr and are generally in good agreement. The good age agreement of a boulder surface (TU-1C) that is significantly older than the other boulder ages from this moraine confirm the suspicion, that it was exposed to cosmic radiation previous to its last deposition (Blard et al., 2009, 2013). In contrast, the 36Cl age of the roche moutonnée surface (TU2) is significantly younger than the corresponding 3He age, but fits well with the adjacent moraine mean age. It thus arises the question if the 3He

  4. Quality assurance and 36Cl program at SUERC: Implications to landscape evolution research

    NASA Astrophysics Data System (ADS)

    Wilcken, Klaus; Freeman, Stewart; Phillips, Richard; Schnabel, Christoph; Binnie, Steven; Dougans, Andrew; Dunai, Tibor; Cowie, Patience; Roberts, Gerald

    2010-05-01

    In situ-produced cosmogenic nuclei, made by cosmic ray induced nuclear reactions cumulatively on exposed surfaces, are natural chronometers and valuable tools for environmental and geological research. Cosmogenic 36Cl (t1-2=3e5 yr) is dominantly produced in spallation reactions on Ca and K, and via neutron capture on 35Cl, and hence is applicable to a range of lithologies for studying events within the last 1 Myr or so. The different 36Cl production mechanisms result in versatility but also challenging data interpretation when unravelling the measured 36Cl concentrations. The main difficulty in utilising 36Cl for environmental and geological research arises from the stable isobar 36S. However, if high enough ion energies are available, these two isotopes can be separated based upon their different rate of energy loss in matter. This has typically required large (10-15 MV) legacy nuclear physics particle accelerators but recently it has been shown that sufficient separation can be achieved with much lower ion energies than before (~30 MeV); the detector resolution being improved by using uniform thin (~30 nm) Silicon rich Nitride membranes as a detector window to minimise energy losses and peak broadening. As a consequence, measurements can now be done with 5 MV, or even smaller, modern accelerator mass spectrometers utilising gas stripping to produce the highest possible quality beams. Accordingly a new class of commercial purpose-build 5-6 MV 36Cl-capable spectrometers is being deployed around the globe with additional measurement capacity greater than that of the installed base. This should increase accessibility and promote wider and more varied 36Cl use. However, laborious sample preparation chemistry and production rate uncertainties remain difficulties. An example 36Cl programme utilising the 5 MV accelerator mass spectrometer at SUERC will be presented. Our internal quality assurance program shows that no external uncertainty beyond 3% counting statistics is

  5. A study of 36Cl production in the early Solar System

    NASA Astrophysics Data System (ADS)

    Bowers, Matthew R.

    Short-lived radionuclides (SLRs) with lifetimes tau < 100 Ma are known to have been extant when the Solar System formed 4.568 billion years ago from meteoritic studies of their decay products. Identifying the origins of SLRs can provide insight into the origins and timescales of our Solar System and the processes that shaped it. There are two proposed production scenarios for the origins of SLRs with tau < 5 Ma. Freshly synthesized material could be incorporated in the Solar System by a nearby stellar source (e.g., supernova, AGB star, Wolf-Rayet star), or SLRs could have also been produced by the bombardment of gas and dust by solar energetic particles (SEP) emitted by our young Sun. The origin of extinct 36Cl (t1/2 = 0.301 Ma) in the early Solar System is thought to have been produced by local particle irradiation. However the models that attempt to recreate the production of 36Cl in the early Solar System lack experimental data for the nuclear reactions considered. The first measurement of the 33S(alpha,p) 36Cl reaction, an important reaction in the production of 36Cl , was performed. The cross section measurement was performed by bombarding a target and collecting the recoiled 36Cl atoms produced in the reaction, chemically processing the samples, and measuring the 36Cl/Cl concentration of the samples with accelerator mass spectrometry (AMS). The cross section was measured at six energies that ranged from 0.70 up to 2.42 MeV/A, within the SEP energy spectrum. The experimental results were found to be systematically higher than the predicted cross sections. However, the deviations lead to < 7 % increase in total production of 36Cl under the x-wind model. From the experimental measurement and a study of the other reactions' contributions to 36Cl production, 36Cl could have been produced close to the protoSun by reactions on Ca targets using the x-wind model, or in a late-stage irradiation event on a volatile-rich reservoir by 3He and alpha reactions on S targets.

  6. Further Exploration of the 33S(α,p)36Cl Reaction Cross Section

    NASA Astrophysics Data System (ADS)

    Skulski, Michael; Anderson, Tyler; Beard, Mary; Collon, Philippe; Lu, Wenting; Ostdiek, Karen

    2015-10-01

    Short-lived radionuclides (SLRs) are extant from the Early Solar System (ESS) and useful for dating products of ESS processes. The SLR 36Cl was potentially produced by solar energetic particles incident on gas and dust in the protoplanetary disk. Measurement of the cross section of the reaction 33S(α,p)36Cl, which contributes significantly to the abundance of 36Cl, is an important input in solar irradiation models regarding the determination of elemental abundances, and is thus of great interest. In a previous measurement performed by Bowers et al. (2013), the cross section of this reaction was studied using a combination of activation of a 4He gas cell and analyzing the produced 36Cl via Accelerator Mass Spectrometry (AMS) over an energy range of 0.7 - 2.42 MeV/A. The result of this measurement was a significantly higher yield of 36Cl than predicted by Hauser-Feshbach cross section calculations. In light of the paper by Mohr (2013), the same activation was repeated at the University of Notre Dame at intermediate energies to study the cross section further, using the same combination of activation and AMS. The results of this measurement will be presented.

  7. Study of nuclear reactions producing 36Cl by micro-AMS

    NASA Astrophysics Data System (ADS)

    Luís, H.; Jesus, A. P.; Fonseca, M.; Cruz, J.; Galaviz, D.; Franco, N.; Alves, E.

    2016-01-01

    36Cl is one of several short to medium lived isotopes (as compared to the earth age) whose abundances at the earlier solar system may help to clarify its formation process. There are two generally accepted possible models for the production of this radionuclide: it originated from the ejecta of a nearby supernova (where 36Cl was most probably produced in the s-process by neutron irradiation of 35Cl) and/or it was produced by in-situ irradiation of nebular dust by energetic particles (mostly, p, a, 3He -X-wind irradiation model). The objective of the present work is to measure the cross section of the 37Cl(p,d)36Cl and 35Cl(d,p)36Cl nuclear reactions, by measuring the 36Cl content of AgCl samples (previously bombarded with high energy protons and deuterons) with AMS, taking advantage of the very low detection limits of this technique for chlorine measurements. For that, the micro-AMS system of the LF1/ITN laboratory had to be optimized for chlorine measurements, as to our knowledge this type of measurements had never been performed in such a system (AMS with micro-beam). Here are presented the first results of these developments, namely the tests in terms of precision and reproducibility that were done by comparing AgCl blanks irradiated at the Portuguese National Reactor with standards produced by the dilution of the NIST SRM 4943 standard material.

  8. Measurement of 26Al for atmospheric and climate research and the potential of 26Al/ 10Be ratios

    NASA Astrophysics Data System (ADS)

    Auer, M.; Kutschera, W.; Priller, A.; Wagenbach, D.; Wallner, A.; Wild, E. M.

    2007-06-01

    The measurement of the paired cosmogenic radionuclides 26Al and 10Be in environmental samples has potential applications in atmospheric and climate research. For this study, we report the first measurements of the 26Al/10Be atomic ratio in tropospheric aerosol samples from sites in Europe and Antarctica performed at the Vienna Environmental Research Accelerator (VERA). These initial results show that the 26Al/10Be atomic ratio in tropospheric aerosols averages 1.78 × 10-3 and does not vary significantly between the different locations. We also report results of systematic investigations of the ionization and detection efficiency which we performed to improve the measurement precision for 26Al by AMS. Maximum detection efficiencies of up to 9 × 10-4 (in units of 26Al atoms detected/initial) were achieved for chemically pure Al2O3, while for atmospheric samples we reached efficiencies of up to 2.2 × 10-4.

  9. The sup 36 Cl ages of the brines in the Magadi-Natron basin, east Africa

    SciTech Connect

    Kaufman, A.; Margaritz, M.A.; Hollos, G. ); Paul, M.; Boaretto, E. ); Hillaire-Marcel, C. ); Taieb, M. )

    1990-10-01

    The depression in the East African Rift which includes both Lake Magadi and Lake Natron forms a closed basin within which almost all the dissolved chloride originates in precipitation, since there is no important source of very ancient sedimentary chloride. This provides an ideal setting for the evaluation of the {sup 36}Cl methodology as a geochemical and hydrological tracer. The main source of recent water, as represented by the most dilute samples measured, is characterized by a {sup 36}Cl/Cl ratio of 2.5 {times} 10{sup {minus}14}, in agreement with the calculated value expected in precipitation. Surface evaporation increases the chlorinity of the local freshwater inflow by about a factor of 110 without changing the isotopic ratio, indicating that little chloride enters the system in the form of sediment leachate. A second type of brine found in the basin occurs in a hot deep groundwater reservoir and is characterized by lower {sup 36}Cl/Cl ratios (<1.2 {times} 10{sup {minus}14}). By comparing this value with the 2.5 {times} 10{sup {minus}14} in recent recharge, one obtains an approximate salt accumulation age of 760 Ka which is consistent with thee time of the first appearance of the lake. These older brines also have lower {sup 18}O and {sup 2}H values which indicate that they were recharged during a climatically different era. The {sup 36}Cl/Cl ratios in the inflowing waters and in the accumulated brine, together with the known age of the Lake Magadi basin, may be used to estimate the importance of the hypogene and epigene, as opposed to the meteoric, mode of {sup 36}Cl production. Such a calculation shows that the hypogene and epigene processes together contribute less than 6% of the total {sup 36}Cl present in the lake.

  10. Probing Galactic 26Al with Exotic Ion Beams

    SciTech Connect

    Chen, Alan A.

    2006-07-12

    The goal of understanding the production of galactic 26Al brings together progress in nuclear astrophysics from observations, theory, meteoritics, and laboratory experiments. In the case of experimental work, nuclear reactions involving unstable isotopes are being studied to elucidate the production of 26Al in stellar explosive nucleosynthesis. We discuss a direct measurement of the 26Al(p,{gamma})27Si reaction with the DRAGON collaboration at TRIUMF, and a measurement of 25Al+p elastic scattering with the CRIB (CNS-U.Tokyo) collaboration, toward constraining the 25Al(p,{gamma})26Si reaction.

  11. Probing Galactic 26Al with Exotic Ion Beams

    NASA Astrophysics Data System (ADS)

    Chen, Alan A.

    2006-07-01

    The goal of understanding the production of galactic 26Al brings together progress in nuclear astrophysics from observations, theory, meteoritics, and laboratory experiments. In the case of experimental work, nuclear reactions involving unstable isotopes are being studied to elucidate the production of 26Al in stellar explosive nucleosynthesis. We discuss a direct measurement of the 26Al(p,γ)27Si reaction with the DRAGON collaboration at TRIUMF, and a measurement of 25Al+p elastic scattering with the CRIB (CNS-U.Tokyo) collaboration, toward constraining the 25Al(p,γ)26Si reaction.

  12. Production rates of 36Cl in basalts from the calibration site of Fuerteventura, Canary Islands

    NASA Astrophysics Data System (ADS)

    Mai, K.

    2009-09-01

    Age determination based on cosmogenic nuclides is an important tool to investigate landscape development and age relations of geologically very young materials. The aim of this study is to contribute data to establish age determination of the basis of cosmogenic 36Cl production as a generally reliable method. 36Cl is a radionuclide that is in situ produced by cosmic radiation at the earth surface. It is formed by spallation from Ca, K, Ti, and Fe, by thermal neutron capture in 35Cl, and by muogenic production from Ca and K. The concentration of the cosmogenic nuclide provides a measure of the exposure age of the surface, but also of the exposure history which may include periods of burial or erosion. Several factors such as the geographic position of the site, the topographic shielding of the surrounding hillside and the sample thickness or sampling depth influence the effective amount of radiation hitting the surface and are taken into account by applying appropriate scaling factors. Basalt samples from the mid-latitude, low altitude calibration site of Fuerteventura, Canary Islands were collected and the production rates of 36Cl were determined. Geologically young samples covering an age range of approximately 50 to 400 ka could be collected from a number of flows, which suit the time span that can be covered with 36Cl age determination. The age was independently determined with the 40Ar/39Ar method. From nine lava flows 7 or 8 samples were collected whose surface structures indicated as little erosion as possible. ICP and XRF measurements proved that the basalts were very similar in chemical composition. The preparation of the AMS samples followed generally the procedure established by Stone et al. (1996b). The measurements were performed at the AMS facility at the University of Utrecht. From the results of the measurements total chlorine concentrations the amount of 36Cl, and the production rates were deduced. The high variability of the production rates for

  13. Ion irradiation of 37Cl implanted nuclear graphite: Effect of the energy deposition on the chlorine behavior and consequences for the mobility of 36Cl in irradiated graphite

    NASA Astrophysics Data System (ADS)

    Toulhoat, N.; Moncoffre, N.; Bérerd, N.; Pipon, Y.; Blondel, A.; Galy, N.; Sainsot, P.; Rouzaud, J.-N.; Deldicque, D.

    2015-09-01

    Graphite is used in many types of nuclear reactors due to its ability to slow down fast neutrons without capturing them. Whatever the reactor design, the irradiated graphite waste management has to be faced sooner or later regarding the production of long lived or dose determining radioactive species such as 14C, 3H or 36Cl. The first carbon dioxide cooled, graphite moderated nuclear reactors resulted in a huge quantity of irradiated graphite waste for which the management needs a previous assessment of the radioactive inventory and the radionuclide's location and speciation. As the detection limits of usual spectroscopic methods are generally not adequate to detect the low concentration levels (<1 ppm) of the radionuclides, we used an indirect approach based on the implantation of 37Cl, to simulate the presence of 36Cl. Our previous studies show that temperature is one of the main factors to be considered regarding the structural evolution of nuclear graphite and chlorine mobility during reactor operation. However, thermal release of chlorine cannot be solely responsible for the depletion of the 36Cl inventory. We propose in this paper to study the impact of irradiation and its synergetic effects with temperature on chlorine release. Indeed, the collision of the impinging neutrons with the graphite matrix carbon atoms induces mainly ballistic collisions. However, a small part of the recoil carbon atom energy is also transferred to the lattice through electronic excitation. This paper aims at elucidating the effects of the different irradiation regimes (ballistic and electronic) using ion irradiation, on the mobility of implanted 37Cl, taking into account the initial disorder level of the nuclear graphite.

  14. Shielding Effects on 10Be and 26Al in Diogenites

    NASA Astrophysics Data System (ADS)

    Welten, K. C.; Lindner, L.; van der Borg, K.; Loeken, Th.; Schultz, L.

    1995-09-01

    Due to the attenuation of primary particles and the variations in secondary part fluxes with depth, production rates of cosmogenic nuclides are affected by the s shape of the irradiated object. The effects of shielding conditions on the produduction rates of noble gases can be estimated on the basis of the cosmogenic 22Ne/21Ne r [1]. For the production of cosmogenic radionuclides, shielding studies mainly fo on large meteorites like St. Severin [2], Knyahinya [3], Chico [4] and Jilin [5] estimated preatmospheric radii between 25 and 85 cm. The 10Be and 26Al production were also measured in three smaller meteorites, but the cosmogenic 22Ne/21Ne rat were obscured by large amounts of trapped neon [6]. Therefore we carried out a systematic study on the 10Be and 26Al activities as a function of the 22Ne/21Ne in 7 non-Antarctic and 15 Antarctic diogenite samples. Diogenites show exposure long enough (>10 Ma) to have reached saturation levels for 10Be and 26Al and are similar to ordinary chondrites with respect to the target element composition fo production of 10Be, 26Al and Ne isotopes. The measured 10Be and 26Al activities were normalized to average diogenite compo on the basis of ICP and XRF measurements and the experimental production rate eq of [7] and [8]. For the Antarctic samples with known terrestrial ages [9] correc were made for radioactive decay. In figure 1, the resulting 10Be and 26Al production rates are plotted against the 22Ne/21Ne ratios, which were measured on the same The solid lines represent the results of an exponential fitting procedure, from two samples were excluded: EET83246 because of SCR-produced 26Al and LEW88008 be of an anomalously low 26Al/10Be ratio, which is not yet understood. Figure 1 illustrates that the 10Be and 26Al production rates are similarly affect shielding conditions: both 10Be and 26Al decrease about 30 - 40% when going from objects with low 22Ne/21Ne ratios (<1.10) to small objects with high 22Ne/21Ne r (>1.25). Recently

  15. Distribution and chemical fate of 36Cl-chlorine dioxide gas during the fumigation of tomatoes and cantaloupe

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The distribution and chemical fate of 36Cl-ClO2 gas subsequent to fumigation of tomatoes or cantaloupe was investigated as was major factors that affect the formation of chloroxyanion byproducts. Approximately 22% of the generated 36Cl-ClO2 was present on fumigated tomatoes after a 2-hour exposure t...

  16. Measurement of cosmogenic /sup 36/Cl/Cl in young volcanic rocks: An application of accelerator mass spectrometry in geochronology

    SciTech Connect

    Leavy, B.D.; Phillips, F.M.; Elmore, D.; Kubik, P.W.

    1987-01-01

    We have measured /sup 36/Cl/Cl ratios in a number of young volcanic rocks in order to test the feasibility of using /sup 36/Cl buildup as a geochronometer for materials less than about 700,000 years old. All of the analyzed rocks have been dated independently using K-Ar or other radiometric dating methods and have exposure histories that are known or can be reasonably assumed. Measured /sup 36/Cl/Cl ratios in these rocks are in good agreement with the calculated in-situ /sup 36/Cl buildup curve. These analyses indicate that AMS measurement of /sup 36/Cl buildup in young rocks is a potentially powerful new method for dating materials that had previously been undatable, and as such will have broad applications in volcanology, tectonics, geophysics, and Quaternary research.

  17. 36Cl: A tracer in groundwater in the aquia formation of Southern Maryland

    USGS Publications Warehouse

    Purdy, C.B.; Mignerey, A.C.; Helz, G.R.; Drummond, D.D.; Kubik, P.W.; Elmore, D.; Hemmick, T.

    1987-01-01

    The Aquia Formation (Paleocene) of Southern Maryland, a marine unit consisting predominantly of quartz sands, but containing 20-40% glauconite, represents one of the many productive, heavily pumped aquifers of the Southeastern Coastal Plain. An unusually high 36Cl activity ( ~ 15 ?? modem water) measured in an outcrop sample is interpreted as a result of the bomb pulse input. About 25 km downdip from the recharge area, a minimum in total chloride concentration occurs. This minimum is thought to correlate with the latest low-stand of sea-level, and thus to provide time information which is in general agreement with ages calculated from hydrodynamic data. However, significant increases in the 36Cl concentrations are observed along the flow path which may be due to ion filtration or to leakage of modem, bomb-contaminated water into the Aquia aquifer. ?? 1987.

  18. Long-term measurements of 36Cl to investigate potential solar influence on the decay rate

    NASA Astrophysics Data System (ADS)

    Kossert, Karsten; Nähle, Ole J.

    2014-03-01

    Recently, Jenkins et al. [6] reported on fluctuations in the detected decay events of 36Cl which were measured with a Geiger-Müller counter. Experimental data of 32Si measured by means of an end-window gas-flow proportional counter at the Brookhaven National Laboratory show similar periodicity, albeit a different amplitude. Jenkins et al. interpret the fluctuations as evidence of solar influence on the decay rates of beta-decaying radionuclides.

  19. 36Cl ages of deep saline groundwater in coastal sedimentary areas in Japan

    NASA Astrophysics Data System (ADS)

    Tosaki, Y.; Morikawa, N.; Kazahaya, K.; Yasuhara, M.; Takahashi, H.; Horiguchi, K.; Sato, T.; Takahashi, M.; Inamura, A.

    2015-12-01

    Climate-induced sea-level fluctuations can have impacts on groundwater flow regimes, especially in coastal areas. A sea level decline leads to a seaward movement of the discharge area of regional groundwater flow system, accompanying increased hydraulic heads in aquifers that enhances deeper groundwater flow. It also brings drastic changes in shorelines and associated topography of coastal areas, which potentially affect groundwater flow regimes. Therefore, an assessment of the influence of sea-level change on groundwater system is especially important. In this study, we focus on several sedimentary basins in Japan, including the Ishikari Plain, the Tsugaru Plain, and the Kanto Plain. Saline groundwater samples were collected from deep boreholes located over the plains, and analyzed for 36Cl/Cl ratios. Several rock samples taken from each area were measured for whole-rock chemical compositions to determine the secular equilibrium 36Cl/Cl ratios in deep aquifers. The obtained 36Cl ages are generally greater than 100 kyr, and tend to become older in inland areas. These age distribution patterns for each area are compared with the locations of past shorelines. The results may show some factors, including topography and geology, which may control the influence of sea-level change on groundwater systems in coastal sedimentary areas. Acknowledgement: Main part of this research project has been conducted as the regulatory supporting research funded by the Secretariat of the Nuclear Regulation Authority, Japan.

  20. Cosmogenic {sup 36}Cl accumulation in unstable landforms 1. Effects of the thermal neutron distribution

    SciTech Connect

    Liu, B.; Phillips, F.M.; Stone, W.D.; Fabryka-Martin, J.T.; Fowler, M.M.

    1994-11-01

    Cosmogenic nuclides produced in situ within minerals at the surface of the Earth are proving to be an effective means of assessing geomorphic histories. The use of multiple cosmogenic nuclides permits both exposure times and erosion rates to be determined. However, if two nuclides are produced only by spallation reactions, the systematic differences in their accumulation rates depend only on the differences in their production rates and half-lives. The relatively small differences that result require a high degree of analytical precision to yield useful results. In contrast to other spallogenic nuclides, {sup 36}Cl is also produced by low-energy neutron, absorption, which creates a different pattern of production as a function of depth. We have measured the thermal flux with depth in a concrete block using {sup 3}He-filled neutron detectors. The measured thermal neutron profile agrees well with predictions from a simple diffusion-based thermal neutron distribution model. Calculations of {sup 36}Cl production using the model suggest that the use of {sup 36}Cl along with a purely spallogenic nuclide to determine erosion rates and exposure times should be less sensitive to analytical error than are determinations from two purely spallogenic nuclides. 31 refs., 7 figs., 3 tabs.

  1. Some possible evolutionary scenarios suggested by 36Cl measurements in Guarani aquifer groundwaters.

    PubMed

    Cresswell, R G; Bonotto, D M

    2008-08-01

    The Guarani aquifer underlies 1.2 M km2 in the Paraná sedimentary basin of South America and is an important source of water for industry, agriculture, and domestic supplies. To determine the sustainability of this aquifer we need to understand the dynamics of the groundwater system. This paper describes the first 36Cl measurements on aquifer groundwaters and some measurements on South American rainwaters, thought to be indicative of the recharge water. The results are compared to previous work in the region, including other radioisotope analyses. A simple model is developed, incorporating radioactive decay, allowing scenarios to be developed for mixing different waters at different mixing rates. Thus, mixing scenarios consistent with other hydrogeological and hydrogeochemical data could be assessed. A model that mixes fresh recharging waters with formational waters, that contain elevated chloride levels, but low (in situ) 36Cl levels, can explain most of the results presented here. The expectation that rainwater samples would provide a good end-member for modelling recharge proved problematic, however. As a consequence, it is suggested that either: the recharge waters are not sourced from the same locations as the rains; that the current rainfall and fallout conditions were significantly different in the past; or that the low levels of chloride in rainfall may have allowed some contamination of the samples by old (36Cl-free) chloride during the recharge process.

  2. Cosmogenic 36Cl ages of Quaternary basalt flows in the Mojave Desert, California, USA

    NASA Astrophysics Data System (ADS)

    Phillips, Fred M.

    2003-07-01

    Basalt flows provide excellent opportunities for calibration and intercomparison of Quaternary dating methods, remote sensing methods, and rates of geomorphic processes. The immediate motivation for this study was to provide chronology for a blind test of the utility of rock varnish microstratigraphy as an indicator of the age of flow emplacement. Five basaltic eruptive centers in the Mojave Desert of California were sampled for cosmogenic 36Cl analysis. Multiple samples were taken from most centers and, with one exception, produced good agreement. Assuming a surficial erosion rate of 1 mm/kyr -1, the flows yielded the following ages: Amboy Crater, 79±5 ka; Pisgah Crater, 22.5±1.3 ka; Cima field, I-Cone, 27±1.3 ka; Cima field, A-Cone, 21±1.6 ka and 11.5±1.5 ka; Cima field, flow of unidentified origin, 46±2 ka. The ages from the Cima I and A cones are in good agreement with previous cosmogenic 3He dating. Ages from the three previously undated flows are significantly older than previous estimates based on flow appearance. Tanzhou Liu performed varnish microstratigraphic analysis on samples collected from the same sites. His results were submitted for publication without knowledge of the 36Cl ages. His age estimates agree well with the 36Cl ages for the three previously undated flows, strongly supporting the validity of varnish microstratigraphy as a chronological correlation tool.

  3. Cosmogenic 36Cl in karst waters from Bunker Cave North Western Germany - A tool to derive local evapotranspiration?

    NASA Astrophysics Data System (ADS)

    Münsterer, C.; Fohlmeister, J.; Christl, M.; Schröder-Ritzrau, A.; Alfimov, V.; Ivy-Ochs, S.; Wackerbarth, A.; Mangini, A.

    2012-06-01

    Monthly rain and drip waters were collected over a period of 10 months at Bunker Cave, Germany. The concentration of 36Cl and the 36Cl/Cl-ratios were determined by accelerator mass spectrometry (AMS), while stable (35+37)Cl concentrations were measured with both, ion chromatography (IC) and AMS. The measured 36Cl-fluxes of (0.97 ± 0.57) × 104 atoms cm-2 month-1 (0.97 atoms m-2 month-1) in precipitation were on average twice as high as the global mean atmospheric production rate. This observation is consistent with the local fallout pattern, which is characterized by a maximum at mid-latitudes. The stable chloride concentration in drip waters (ranging from 13.2 to 20.9 mg/l) and the 36Cl-concentrations (ranging from 16.9 × 106 to 35.3 × 106 atoms/l) are a factor of 7 and 10 above the values expected from empirical evapotranspiration formulas and the rain water concentrations, respectively. Most likely the additional stable Cl is due to human impact from a nearby urban conglomeration. The large 36Cl-enrichment is attributed to the local evapotranspiration effect, which appears to be higher than the calculated values and to additional bomb-derived 36Cl from nuclear weapons tests in the 1950s and 60s stored in the soil above the cave. In the densely vegetated soil above Bunker Cave, 36Cl seems not to behave as a completely conservative tracer. The bomb derived 36Cl might be retained in the soil due to uptake by minerals and organic material and is still being released now. Based on our data, the residence time of 36Cl in the soil is estimated to be about 75-85 years.

  4. Synthesis of [(14) C]omarigliptin.

    PubMed

    Ren, Sumei; Gauthier, Donald; Marques, Rosemary; Helmy, Roy; Hesk, David

    2016-08-01

    An efficient synthesis for [(14) C]Omarigliptin (MK-3102) is described. The initial synthesis of a key (14) C-pyrazole moiety did not work due to the lack of stability of (14) C-DMF-DMA reagent. Thus, a new radiolabeled synthon, (14) C-biphenylmethylformate, was synthesized from (14) C-sodium formate in one step in 92% yield and successfully used in construction of the key (14) C-pyrazole moiety. Regioselective N-sulfonation of the pyrazole moiety was achieved through a dehydration-sulfonation-isomerization sequence. [(14) C]MK 3102 was synthesized in five steps from (14) C-biphenylmethylformate with 25% overall yield. PMID:27334864

  5. Determination of paleoseismic activity over a large time-scale: Fault scarp dating with 36Cl

    NASA Astrophysics Data System (ADS)

    Mozafari Amiri, Nasim; Tikhomirov, Dmitry; Sümer, Ökmen; Özkaymak, Çaǧlar; Uzel, Bora; Ivy-Ochs, Susan; Vockenhuber, Christof; Sözbilir, Hasan; Akçar, Naki

    2016-04-01

    Bedrock fault scarps are the most direct evidence of past earthquakes to reconstruct seismic activity in a large time-scale using cosmogenic 36Cl dating if built in carbonates. For this method, a surface along the fault scarp with a minimum amount of erosion is required to be chosen as an ideal target point. The section of the fault selected for sampling should cover at least two meters of the fault surface from the lower part of the scarp, where intersects with colluvium wedge. Ideally, sampling should be performed on a continuous strip along the direction of the fault slip direction. First, samples of 10 cm high and 15 cm wide are marked on the fault surface. Then, they are collected using cutters, hammer and chisel in a thickness of 3 cm. The main geometrical factors of scarp dip, scarp height, top surface dip and colluvium dip are also measured. Topographic shielding in the sampling spot is important to be estimated as well. Moreover, density of the fault scarp and colluvium are calculated. The physical and chemical preparations are carried in laboratory for AMS and chemical analysis of the samples. A Matlab® code is used for modelling of seismically active periods based on increasing production rate of 36Cl following each rupture, when a buried section of a fault is exposed. Therefore, by measuring the amount of cosmogenic 36Cl versus height, the timing of major ruptures and their offsets are determined. In our study, Manastır, Mugırtepe and Rahmiye faults in Gediz graben, Priene-Sazlı, Kalafat and Yavansu faults in Büyük Menderes graben and Ören fault in Gökava half-graben have been examined in the seismically active region of Western Turkey. Our results reconstruct at least five periods of high seismic activity during the Holocene time, three of which reveal seismic ruptures beyond the historical pre-existing data.

  6. FINDING TRACERS FOR SUPERNOVA PRODUCED {sup 26}Al

    SciTech Connect

    Young, Patrick A.; Ellinger, Carola I.; Arnett, David; Fryer, Chris L.; Rockefeller, Gabriel

    2009-07-10

    We consider the cospatial production of elements in supernova explosions to find observationally detectable proxies for enhancement of {sup 26}Al in supernova ejecta and stellar systems. Using four progenitors, we explore a range of one-dimensional explosions at different energies and an asymmetric three-dimensional explosion. We find that the most reliable indicator of the presence of {sup 26}Al in unmixed ejecta is a very low S/Si ratio ({approx}0.05). Production of N in O/S/Si-rich regions is also indicative. The biologically important element P is produced at its highest abundance in the same regions. Proxies should be detectable in supernova ejecta with high spatial resolution multiwavelength observations, but the small absolute abundance of material injected into a proto-planetary disk makes detection unlikely in existing or forming stellar/planetary systems.

  7. Depth dependence of soil carbonate accumulation based on cosmogenic [sup 36]Cl dating

    SciTech Connect

    Liu, B.; Phillips, F.M. ); Elmore, D.; Sharma, P. )

    1994-12-01

    Indurated pedogenic carbonate layers (calcretes) are common in soils on stable surfaces in arid to semiarid climates. The morphology and composition of calcretes provide important information on the geomorphic and climatic histories of the regions where they are formed, but they have proved difficult to date with conventional radiometric methods. We report cosmogenic [sup 36]Cl-buildup ages from three fractions (leachable Cl, carbonate, silicate) of a calcrete from the surface of an alluvial slope below the Ajo Mountains in southern Arizona. All three fractions give reasonably concordant ages, ranging from 700 ka at the base of the calcrete horizon to 200 ka at its top. These ages are in good agreement both with estimates of age based on correlation with similar, independently dated, soils in the region and with [sup 36]Cl-buildup ages on surficial boulders. These results support the ideas that calcretes accumulate upward with time and that water movement through the carbonate matrix is very limited after induration. 19 refs., 2 figs., 1 tab.

  8. 36Cl/Cl ratios in geothermal systems: preliminary measurements from the Coso Field

    SciTech Connect

    Nimz, G.J.; Moore, J.N.; Kasameyer, P.W.

    1997-07-01

    The {sub 36}Cl/Cl isotopic composition of chlorine in geothermal systems can be a useful diagnostic tool in characterizing hydrologic structure, in determining the origins and age of waters within the systems, and in differentiating the sources of chlorine (and other solutes) in the thermal waters. The {sub 36}Cl/Cl values for several geothermal water samples and reservoir host rock samples from the Coso, California geothermal field have been measured for these purposes. The results indicate that most of the chlorine is not derived from the dominant granitoid that host the geothermal system. If the chlorine was originally input into the Coso subsurface through meteoric recharge, that input occurred at least 1-1.25 million years ago. The results suggest that the thermal waters could be connate waters derived from sedimentary formations, presumably underlying and adjacent top the granitic rocks, which have recently migrated into the host rocks. Alternatively, most of the chlorine but not the water, may have recently input into the system from magmatic sources. In either case, the results indicate that most of the chlorine in the thermal waters has existed within the granitoid host rocks for no more than about 100,00-200,00 years. this residence time for the chlorine is similar to residence times suggested by other researchers for chlorine in deep groundwaters of the Mono Basin north of the Coso field.

  9. 36Cl measurements in Hiroshima granite samples as part of an international intercomparison study. Results from the Munich group.

    PubMed

    Huber, T; Rühm, W; Hoshi, M; Egbert, S D; Nolte, E

    2003-04-01

    Within the effort to resolve the so-called Hiroshima neutron discrepancy, an international intercomparison study has been carried out on granite samples from Hiroshima, with participating institutions from Japan, the US, and Germany. (36)Cl and (152)Eu produced in these samples by thermal neutrons from the A-bomb explosion were assessed independently by means of different techniques. At the Maier-Leibnitz-Laboratory near Munich, Germany, (36)Cl concentrations were measured by accelerator mass spectrometry. Measured (36)Cl/Cl ratios ranged from 1,670 x 10(-13) (at a distance of 146 m from the hypocenter) to 2.2 x 10(-13) (at a distance of 1,163 m from the hypocenter). One granite sample not exposed to A-bomb neutrons was measured as a control, and a (36)Cl/Cl ratio of 2.6 x 10(-13) was obtained. On average, our experimental results are 20-30% lower than those provided by model calculations based on the dosimetry system DS86. The results presented here do not support previous assessments of (36)Cl, (60)Co, and (152)Eu which had suggested much larger thermal neutron fluences than those calculated on the basis of DS86 for distances from the hypocenter of more than 1,000 m.

  10. Short lived 36Cl and its decay products 36Ar and 36S in the early solar system

    NASA Astrophysics Data System (ADS)

    Turner, G.; Crowther, S. A.; Burgess, R.; Gilmour, J. D.; Kelley, S. P.; Wasserburg, G. J.

    2013-12-01

    Variable excesses of 36S have previously been reported in sodalite in the Allende and Ningqiang meteorites and used to infer the presence of 36Cl in the early solar system. Until now no unambiguous evidence of the major decay product, 36Ar (98%), has been found. Using low fluence fast neutron activation we have measured small amounts of 36Ar in the Allende sodalite Pink Angel, corresponding to 36Cl/35Cl = (1.9 ± 0.5) × 10-8. This is a factor of 200 lower than the highest value inferred from 36S excesses in sodalite. High resolution I-Xe analyses confirm that the sodalite formed between 4561 and 4558 Ma ago. The core of Pink Angel sodalite yielded a precise formation age of 4559.4 ± 0.6 Ma. Deposition of sodalite containing live 36Cl, seven million years or so after the formation of the CAI, appears to require a local production mechanism involving intense neutron irradiation within the solar nebula. The constraint imposed by the near absence of neutron induced 128Xe is most easily satisfied if the 36Cl were produced in a fluid precursor of the sodalite. The low level of 36Ar could be accounted for as a result of residual in-situ36Cl decay, up to 1-2 Ma after formation of the sodalite, and/or later diffusive loss, in line with the low activation energy for Ar diffusion in sodalite.

  11. (26)Al investigations at the AMS-laboratory in Lund.

    PubMed

    Faarinen, M; Magnusson, C E; Hellborg, R; Mattsson, S; Kiisk, M; Persson, P; Schütz, A; Skog, G; Stenström, K

    2001-11-01

    At the accelerator mass spectrometry (AMS) laboratory in Lund, a facility for (26)Al analysis is under development. The sensitivity is expected to be several orders of magnitude higher than with standard mass spectrometry. The planned biomedical program includes studies of aluminium uptake, distribution and retention in man. The initial work has been concentrated on the construction and testing of a new dedicated injector for the accelerator and on the preparation of biological samples for aluminium analysis. The current quality of the facility is presented and the first experimental results reported. PMID:11709214

  12. Inventory of site-derived {sup 36}Cl in the Snake River plain aquifier, Idaho National Engineering Laboratory, Idaho

    SciTech Connect

    Beasley, T.M.

    1995-02-01

    Radioactive waste management practices at the U.S. Department of Energy`s Idaho National Engineering Laboratory (INEL) in Idaho have introduced {sup 36}Cl (T{sub 1/2} = 301,000 yr) into the Snake River Plain aquifer underlying the site. The {sup 36}Cl is believed to originate from neutron activation of stable {sup 35}Cl in nuclear fuels (principally) and in reactor cooling/process water. Wastewater releases of {sup 3}H at the INEL have been documented by the site operators for the period 1952 to 1988. During this time, approximately 1.2 PBq of {sup 3}H (30,000 Ci) were introduced to the subsurface through disposal wells and seepage ponds. By sampling a number of monitoring and production wells downgradient from points of introduction, {sup 3}H movement and dispersion in the groundwater have been documented by the U.S. Geological Survey. The present report uses these historical {sup 3}H release and monitoring data to choose hydrologic parameters (matrix porosity and plume penetration depth) that produce concordance between the {sup 3}H release estimates and the inventory calculated from measurements of {sup 3}H in the subsurface. These parameters are then applied to {sup 36}Cl isopleths to generate an estimated {sup 36}Cl inventory in the subsurface. Using assumptions about irradiation times, neutron fluxes, and total fuel processed, as little as 23 g of stable chloride impurity in fuel elements would be adequate to produce the amount of {sup 36}Cl estimated to be in the groundwaters underlying the site. The highest atom concentration of {sup 36}Cl measured onsite (222x10{sup 10} atoms 1{sup -1}) corresponds to an activity level of {approximately}4 pCi 1{sup -1} and represents 0.2 percent of the U.S. Environmental Protection Agency`s (EPA) drinking water standard for this radionuclide (2000 pCi 1{sup -1}).

  13. Using 36Cl data to quantify the paleorecharge in arid region. Example of the North Western Saharan Aquifer System.

    NASA Astrophysics Data System (ADS)

    Oriane Petersen, Jade; Deschamps, Pierre; Gonçalvès, Julio; Hamelin, Bruno; Michelot, Jean-Luc; Guendouz, Abdelhamid; Zouari, Kamel

    2014-05-01

    A comprehensive understanding of large-scale systems such as multi-layer aquifers in sedimentary basins (e.g. North Western Saharan Aquifer System -NWSAS- or the Great Artesian Basin) requires to investigate the recharge history to Quaternary timescale. In fact, for such systems, the residence time of groundwater is often in the order of 100 000 years to 1 million years, the recharge occurring during past, intermittent humid periods paced by the quaternary climatic cycles. In this study, we propose to reconstruct the history of the recharge over the Continental Intercalaire (CI) aquifer, one of the two main aquifers of the NWSAS. It extends over 1 million km2, shared between Algeria, Tunisia and Libya. We focus on the main recharge area of the CI aquifer located in the Algerian Atlas Mountains. Existing chlorine-36 data (36Cl half-life: 301 ka) indicate that groundwater residence time in this system is around 1 million years. A set of modeling approaches is combined to model the theoretical 36Cl/Cl distribution within the aquifer as a function of different recharge scenarios. Seventeen 36Cl/Cl data from two distinct flowpaths provide temporal constraints on groundwater ages. A simple piston model is used to simulate the distribution of theoretical 36Cl along these flowlines as a function of the distance from the outcrop with respect to a recharge scenario. Simplified climatic scenarios are constructed considering humid periods only during interglacial cycles. This allows to define 9 recharge rates (Rh(i)) associated to last interglacials (from marine isotope stages MIS1 to MIS19). In addition, a constant recharge Rg was considered during glacial periods. For each recharge scenario, the recharge values are constrained by using a Markov Chain Monte Carlo (MCMC) inversion, which yields the best agreement between measured and modeled 36Cl/Cl. This MCMC probabilistic inversion approach allows identifying plausible sets of the 10 parameters (9 Rh(i) and Rg) involved in

  14. Evidence from cosmic-ray exposure dating based on 36Cl for the pre-Minoan caldera on Santorini, Greece

    NASA Astrophysics Data System (ADS)

    Athanassas, Constantin; Bourlès, Didier; Braucher, Regis; Druitt, Tim; Nomikou, Paraskevi; Léanni, Laetitia

    2016-04-01

    The physiography of Santorini prior to the Minoan (Late Bronze Age) eruption (17th century BCE) is of great archaeological interest, given the importance of Santorini as a commercial centre and port in the Minoan empire. However, the paleogeography of the pre-Minoan caldera has been a point of controversy: Heiken and McCoy (1984) advocated the existence, in the southern part of the present-day caldera, of a pre-existing caldera formed during the 172 ka Lower Pumice eruption, whereas Druitt and Francaviglia (1992), based on the presence of in situ plinian pumice from the Minoan eruption adhering to the modern cliff, conceived the pre-Minoan (22 ka) caldera as having occupied much of the northern basin of the present-day caldera. With the goal of settling the debate we performed cosmic ray exposure dating employing in situ-produced cosmogenic 36Cl to date different generations of caldera cliffs at Santorini, and hence to identify those cliffs predating the Minoan eruption. Our methodology involved the determination of the in situ-produced cosmogenic 36Cl in basaltic and andesitic rocks cropping out in the cliffs. The samples returned 36Cl CRE ages consistent with previously published field mapping of cliff populations based on geomorphological and stratigraphic arguments (Druitt and Francaviglia 1992), suggesting that much of the present cliff line of northern Santorini predated the Minoan eruption, or was superficially modified by landslips and rockfalls during that eruption. The 36Cl CRE ages enable us to better define the paleogeography of the pre-Minoan caldera. References [1] Druitt, T. H. and Francaviglia, V.1992. Caldera formation on Santorini and the physiography of the islands in the Late Bronze Age. Bulletin of Volcanology 54, 484-493. [2] Heiken G and McCoy F (1984) Caldera development during the Minoan eruption, Thira, Cyclades, Greece. Journal of Geophysical Research: 89 (B10), 8841-8862.

  15. Total radioactive residues and residues of [36Cl]chlorate in market size broilers.

    PubMed

    Smith, David J; Byrd, James A; Anderson, Robin C

    2007-07-11

    The oral administration of chlorate salts reduces the numbers of Gram-negative pathogens in gastrointestinal tracts of live food animals. Although the efficacy of chlorate salts has been demonstrated repeatedly, the technology cannot be introduced into commercial settings without first demonstrating that chlorate residues, and metabolites of chlorate remaining in edible tissues, represent a negligible risk to consumers. Typically, a first step in this risk assessment is to quantify the parent compound and to identify metabolites remaining in edible tissues of animals treated with the experimental compound. The objectives of this study were to determine the pathway(s) of chlorate metabolism in market broilers and to determine the magnitude of chlorate residues remaining in edible tissues. To this end, 12 broilers (6 weeks; 2.70+/-0.34 kg) were randomly assigned to three treatments of 7.4, 15.0, and 22.5 mM sodium [36Cl]chlorate dissolved in drinking water (n=4 broilers per treatment). Exposure to chlorate, dissolved in drinking water, occurred at 0 and 24 h (250 mL per exposure), feed was withdrawn at hour 38, water was removed at hour 48, and birds were slaughtered at hour 54 (16 h after feed removal and 8 h after water removal). The radioactivity was rapidly eliminated in excreta with 69-78% of the total administered radioactivity being excreted by slaughter. Total radioactive residues were proportional to dose in all edible tissues with chloride ion comprising greater than 98.5% of the radioactive residue for the tissue (9.4-97.8 ppm chlorate equivalents). Chlorate residues were typically greatest in the skin (0.33-0.82 ppm), gizzard (0.1-0.137 ppm), and dark muscle (0.05-0.14 ppm). Adipose, liver, and white muscle tissue contained chlorate concentrations from 0.03 to 0.13 ppm. In contrast, chlorate concentrations in excreta eliminated during the 6 h period prior to slaughter ranged from 53 to 71 ppm. Collectively, these data indicate that broilers rapidly

  16. Total radioactive residues and residues of [36Cl]chlorate in market size broilers.

    PubMed

    Smith, David J; Byrd, James A; Anderson, Robin C

    2007-07-11

    The oral administration of chlorate salts reduces the numbers of Gram-negative pathogens in gastrointestinal tracts of live food animals. Although the efficacy of chlorate salts has been demonstrated repeatedly, the technology cannot be introduced into commercial settings without first demonstrating that chlorate residues, and metabolites of chlorate remaining in edible tissues, represent a negligible risk to consumers. Typically, a first step in this risk assessment is to quantify the parent compound and to identify metabolites remaining in edible tissues of animals treated with the experimental compound. The objectives of this study were to determine the pathway(s) of chlorate metabolism in market broilers and to determine the magnitude of chlorate residues remaining in edible tissues. To this end, 12 broilers (6 weeks; 2.70+/-0.34 kg) were randomly assigned to three treatments of 7.4, 15.0, and 22.5 mM sodium [36Cl]chlorate dissolved in drinking water (n=4 broilers per treatment). Exposure to chlorate, dissolved in drinking water, occurred at 0 and 24 h (250 mL per exposure), feed was withdrawn at hour 38, water was removed at hour 48, and birds were slaughtered at hour 54 (16 h after feed removal and 8 h after water removal). The radioactivity was rapidly eliminated in excreta with 69-78% of the total administered radioactivity being excreted by slaughter. Total radioactive residues were proportional to dose in all edible tissues with chloride ion comprising greater than 98.5% of the radioactive residue for the tissue (9.4-97.8 ppm chlorate equivalents). Chlorate residues were typically greatest in the skin (0.33-0.82 ppm), gizzard (0.1-0.137 ppm), and dark muscle (0.05-0.14 ppm). Adipose, liver, and white muscle tissue contained chlorate concentrations from 0.03 to 0.13 ppm. In contrast, chlorate concentrations in excreta eliminated during the 6 h period prior to slaughter ranged from 53 to 71 ppm. Collectively, these data indicate that broilers rapidly

  17. Heterogeneous Distribution of 26Al at the Birth of the Solar System

    NASA Astrophysics Data System (ADS)

    Makide, Kentaro; Nagashima, Kazuhide; Krot, Alexander N.; Huss, Gary R.; Ciesla, Fred J.; Hellebrand, Eric; Gaidos, Eric; Yang, Le

    2011-06-01

    It is believed that 26Al, a short-lived (t 1/2 = 0.73 Ma) and now extinct radionuclide, was uniformly distributed in the nascent solar system (SS) with the initial 26Al/27Al ratio of ~5.2 × 10-5, suggesting an external, stellar origin rather than local, solar source. However, the stellar source of 26Al and the manner in which it was injected into the SS remain controversial: the 26Al could have been produced by an asymptotic giant branch star, a supernova, or a Wolf-Rayet star and injected either into the protosolar molecular cloud, protosolar cloud core, or protoplanetary disk. Corundum (Al2O3) is predicted to be the first condensate from a cooling gas of solar composition. Here we show that micron-sized corundum condensates from 16O-rich (Δ17O ~ -25‰) gas of solar composition recorded heterogeneous distribution of 26Al at the birth of the SS: the inferred initial 26Al/27Al ratio ranges from ~6.5×10-5 to <2×10-6 52% of corundum grains measured are 26Al-poor. Abundant 26Al-poor, 16O-rich refractory objects include grossite- and hibonite-rich calcium-aluminum-rich inclusions (CAIs) in CH (high metal abundance and high iron concentration) chondrites, platy hibonite crystals in CM (Mighei-like) chondrites, and CAIs with fractionation and unidentified nuclear effects CAIs chondrites. Considering the apparently early and short duration (<0.3 Ma) of condensation of refractory 16O-rich solids in the SS, we infer that 26Al was injected into the collapsing protosolar molecular cloud and later homogenized in the protoplanetary disk. The apparent lack of correlation between 26Al abundance and O-isotope composition of corundum grains constrains the stellar source of 26Al in the SS.

  18. 14C-carbaryl residues in hazelnut.

    PubMed

    Yücel, Ulkü; Ilim, Murat; Aslan, Nazife

    2006-01-01

    A hazelnut ocak (shrub growing form) in the field in Black Sea region of Turkey was treated with commercial carbaryl insecticide spiked with 14C-carbaryl. Three months later, the harvested hazelnuts were separated into husk, shell, and kernel components, then homogenized and analyzed. The total and unextractable (bound) 14C-residues were determined by combustion and the extractable 14C-residues were obtained by extracting the samples with methanol. Concentrated extracts were first analyzed by thin layer chromatography (TLC). The extracts were also subjected to a series of liquid-liquid extraction procedures for clean-up and the final extracts were analyzed by high performance liquid chromatography (HPLC). Crude hazelnut oil was also extracted with hexane and analyzed for total 14C-residue. A total of 1.3% of applied radioactivity was recovered from the total nut harvested, with 0.04%, 0.06%, and 1.2% present in shell, kernel, and husk, respectively. The results show that the inedible husk and shell contained 95.7% 14C, whereas the edible kernel contained 4.3% of the total 14C recovered. The terminal 14C-residue in hazelnut kernel and oil did not contain carbaryl and/or its metabolite naphthol.

  19. Production of 26Al by super-AGB stars

    NASA Astrophysics Data System (ADS)

    Siess, L.; Arnould, M.

    2008-10-01

    Context: Super AGB (SAGB) stars have initial masses ranging between 7-11 {M_⊙} and develop efficient hydrogen burning at the base of their convective envelope during their AGB evolution, leading to a substantial production of {}26Alg. Aims: We present the first discussion of the contribution of the SAGB stars to the galactic {}26Alg production, and we estimate the main uncertainties that affect the determination of the {}26Alg yields. Methods: The results of full stellar evolution computations are presented, with special emphasis on the {}26Alg yields from SAGB stars. We also use a postprocessing nucleosynthesis code to quantify the uncertainties associated with the nuclear reaction rates and with the treatment of convection that modifies the thermodynamical conditions at the base of the convective envelope. Results: Hot bottom burning leads to individual SAGB {}26Alg yields that are larger than those from intermediate mass stars, amounting to typical values as high as 5 × 10-5 {M_⊙}. The overall SAGB contribution remains modest, however, not exceeding 0.3 {M_⊙} of the estimated galactic content of 2.8 {M_⊙}. On the other hand, the SAGB 26Al/27Al ratios always exceed 0.01, which is commensurable with the values measured in some SiC grains considered to originate in C-rich AGB stars. However, the isotopic composition of some other elements, particularly nitrogen, is clearly at variance with the observations. We find that the {}26Alg yields are not affected by the pollution induced by the third dredge-ups, but that they strongly depend on the evolution of the temperature at the base of the convective envelope, the determination of which remains highly dependent on the specific convection model used in the stellar computations. Modifications of T_env by ± 10% leads to variations in the {}26Alg yields by a factor of 0.2 to 6. In comparison, the nuclear reaction rate uncertainties have less of an impact, altering the yields by less than a factor of 2.

  20. 26Al-containing acidic and basic sodium aluminum phosphate preparation and use in studies of oral aluminum bioavailability from foods utilizing 26Al as an aluminum tracer

    NASA Astrophysics Data System (ADS)

    Yokel, Robert A.; Urbas, Aaron A.; Lodder, Robert A.; Selegue, John P.; Florence, Rebecca L.

    2005-04-01

    We synthesized 26Al-containing acidic and basic (alkaline) sodium aluminum phosphates (SALPs) which are FDA-approved leavening and emulsifying agents, respectively, and used them to determine the oral bioavailability of aluminum incorporated in selected foods. We selected applicable methods from published syntheses (patents) and scaled them down (∼3000- and 850-fold) to prepare ∼300-400 mg of each SALP. The 26Al was incorporated at the beginning of the syntheses to maximize 26Al and 27Al equilibration and incorporate the 26Al in the naturally-occurring Al-containing chemical species of the products. Near infrared spectroscopy (NIR) and X-ray powder diffraction (XRD) were used to characterize the two SALP samples and some intermediate samples. Multi-elemental analysis (MEA) was used to determine Na, Al and P content. Commercial products were included for comparison. Satisfactory XRD analyses, near infrared spectra and MEA results confirmed that we synthesized acidic and basic SALP, as well as some of the syntheses intermediates. The 26Al-containing acidic and basic SALPs were incorporated into a biscuit material and a processed cheese, respectively. These were used in oral bioavailability studies conducted in rats in which the 26Al present in blood after its oral absorption was quantified by accelerator mass spectrometry. The results showed oral Al bioavailability from acidic SALP in biscuit was ∼0.02% and from basic SALP in cheese ∼0.05%, lower than our previous determination of Al bioavailability from drinking water, ∼0.3%. Both food and water can appreciably contribute to the Al absorbed from typical human Al intake.

  1. Timing of maximum glacial extent and deglaciation from HualcaHualca volcano (southern Peru), obtained with cosmogenic 36Cl.

    NASA Astrophysics Data System (ADS)

    Alcalá, Jesus; Palacios, David; Vazquez, Lorenzo; Juan Zamorano, Jose

    2015-04-01

    Andean glacial deposits are key records of climate fluctuations in the southern hemisphere. During the last decades, in situ cosmogenic nuclides have provided fresh and significant dates to determine past glacier behavior in this region. But still there are many important discrepancies such as the impact of Last Glacial Maximum or the influence of Late Glacial climatic events on glacial mass balances. Furthermore, glacial chronologies from many sites are still missing, such as HualcaHualca (15° 43' S; 71° 52' W; 6,025 masl), a high volcano of the Peruvian Andes located 70 km northwest of Arequipa. The goal of this study is to establish the age of the Maximum Glacier Extent (MGE) and deglaciation at HualcaHualca volcano. To achieve this objetive, we focused in four valleys (Huayuray, Pujro Huayjo, Mollebaya and Mucurca) characterized by a well-preserved sequence of moraines and roches moutonnées. The method is based on geomorphological analysis supported by cosmogenic 36Cl surface exposure dating. 36Cl ages have been estimated with the CHLOE calculator and were compared with other central Andean glacial chronologies as well as paleoclimatological proxies. In Huayuray valley, exposure ages indicates that MGE occurred ~ 18 - 16 ka. Later, the ice mass gradually retreated but this process was interrupted by at least two readvances; the last one has been dated at ~ 12 ka. In the other hand, 36Cl result reflects a MGE age of ~ 13 ka in Mollebaya valley. Also, two samples obtained in Pujro-Huayjo and Mucurca valleys associated with MGE have an exposure age of 10-9 ka, but likely are moraine boulders affected by exhumation or erosion processes. Deglaciation in HualcaHualca volcano began abruptly ~ 11.5 ka ago according to a 36Cl age from a polished and striated bedrock in Pujro Huayjo valley, presumably as a result of reduced precipitation as well as a global increase of temperatures. The glacier evolution at HualcaHualca volcano presents a high correlation with

  2. Seismic slip history of the Pizzalto fault (Central Apennines, Italy) using in situ 36Cl cosmogenic dating

    NASA Astrophysics Data System (ADS)

    Delli Rocioli, Mattia; Pace, Bruno; Benedetti, Lucilla; Visini, Francesco; Guillou, Valery; Bourlès, Didier; Arnorld, Maurice; Aumaître, Georges; Keddadouche, Karim

    2013-04-01

    A prerequisite to constrain fault-based and time-dependent earthquake rupture forecast models is to acquire data on the past large earthquake frequency on an individual seismogenic source. Here we present a paleoseismological study on the Pizzalto fault using the in situ produced cosmogenic nuclide 36Cl (Schlagenhauf et al., 2011). The Pizzalto fault, located in central Italy about 50 km southeast of the epicenter of L'Aquila 2009 earthquake, is about 12 km long, SW dipping and belongs to the 30 km long Rotella-Aremogna active normal fault system. Recent activity along the Pizzalto fault is suggested by the presence of a continuous and linear 2 to 5 m high limestone fault scarp that was sampled every 10 cm at a site located in its particularly well-preserved central portion. 49 samples have been chemically processed and measured, and their 36Cl and Cl concentrations have been determined using isotope dilution mass spectrometry at the French AMS national facility ASTER located at CEREGE. Modeling the in situ 36Cl concentration with the scarp height allow deciphering the age and slip of the last major earthquake events on the fault. To derive those earthquake parameters, we used the published Matlab code from Schlagenhauf et al. (2011) that we implemented with a Monte Carlo approach to explore a large number of earthquake recurrence scenarios varying both the number of events, their slip and their ages. The "a priori" constraints input in the Monte Carlo code were: 1-the number of events, which is given by the stacking of individual probability density functions (assumed to be Gaussian) of each sample concentration; and, 2-the cumulative slip that should be equal to the height of the fault scarp. The first results show that 36Cl concentrations are reproduced better considering five events occurring over the last 5 ka and a previous one at about 13 ka. This suggests that most earthquake events clustered during a period of intense seismic activity preceded by a longer

  3. Translocation of 125I, 75Se and 36Cl to wheat edible parts following wet foliar contamination under field conditions.

    PubMed

    Hurtevent, P; Thiry, Y; Levchuk, S; Yoschenko, V; Henner, P; Madoz-Escande, C; Leclerc, E; Colle, C; Kashparov, V

    2013-07-01

    Apart from radiocaesium and radiostrontium, there have been few studies on the foliar transfer of radionuclides in plants. Consequently, specific translocation factor (ftr) values for (129)I, (79)Se and (36)Cl are still missing from the IAEA reference databases. The translocation of short - lived isotopes, (125)I and (75)Se, and of (36)Cl to wheat grain were measured under field conditions following acute and chronic wet foliar contamination at various plant growth stages in the absence of leaching caused by rain. The translocation factors ranged from 0.02% to 1.1% for (125)I (a value similar to Sr), from 0.1% to 16.5% for (75)Se, and from 1% to 14.9% for (36)Cl. Both (36)Cl and (75)Se were as mobile as Cs. The phenomenological analysis showed that each element displayed a specific behavior. Iodide showed the lowest apparent mobility because of its preferential fixation in or on the leaves and a significant amount probably volatilized. Selenite internal transfer was significant and possibly utilized the sulphur metabolic pathway. However bio - methylation of selenite may have led to increased volatilization. Chloride was very mobile and quickly diffused throughout the plant. In addition, the analysis underlined the importance of plant growth responses to annual variations in weather conditions that can affect open field experiments because plant growth stage played a major role in ftr values dispersion. The chronic contamination results suggested that a series of acute contamination events had an additive effect on translocated elements. The highest translocation value obtained for an acute contamination event was shown to be a good conservative assessment of chronic contamination if data on chronic contamination translocation are lacking. The absence of rain leaching during the experiment meant that this investigation avoided potential radionuclide transfer by the roots, which also meant that radionuclide retention on or in the leaves was maximized. This study was

  4. {sup 14}C depth profiles in Apollo 15 and 17 cores and lunar rock 68815

    SciTech Connect

    Jull, A.J.T.; Cloudt, S.; Donahue, D.J.; Sisterson, J.M.; Reedy, R.C.; Masarik, J.

    1998-09-01

    Accelerator mass spectrometry (AMS) was used to measure the activity vs. depth profiles of {sup 14}C produced by both solar cosmic rays (SCR) and galactic cosmic rays (GCR) in Apollo 15 lunar cores 15001-6 and 15008, Apollo 17 core 76001, and lunar rock 68815. Calculated GCR production rates are in good agreement with {sup 14}C measurements at depths below {approximately}10 cm. Carbon-14 produced by solar protons was observed in the top few cm of the Apollo 15 cores and lunar rock 68815, with near-surface values as high as 66 dpm/kg in 68815. Only low levels of SCR-produced {sup 14}C were observed in the Apollo 17 core 76001. New cross sections for production of {sup 14}C by proton spallation on O, Si, Al, Mg, Fe, and Ni were measured using AMS. These cross sections are essential for the analysis of the measured {sup 14}C depth profiles. The best fit to the activity-depth profiles for solar-proton-produced {sup 14}C measured in the tops of both the Apollo 15 cores and 68815 was obtained for an exponential rigidity spectral shape R{sub 0} of 110--115 MV and a 4 {pi} flux (J{sub 10}, Ep > 10 MeV) of 103--108 protons/cm{sup 2}/s. These values of R{sub 0} are higher, indicating a harder rigidity, and the solar-proton fluxes are higher than those determined from {sup 10}Be, {sup 26}Al, and {sup 53}Mn measurements.

  5. Tritium and 36Cl as constraints on fast fracture flow and percolation flux in the unsaturated zone at Yucca Mountain

    NASA Astrophysics Data System (ADS)

    Guerin, Marianne

    2001-10-01

    An analysis of tritium and 36Cl data collected at Yucca Mountain, Nevada suggests that fracture flow may occur at high velocities through the thick unsaturated zone. The mechanisms and extent of this "fast flow" in fractures at Yucca Mountain are investigated with data analysis, mixing models and several one-dimensional modeling scenarios. The model results and data analysis provide evidence substantiating the weeps model [Gauthier, J.H., Wilson, M.L., Lauffer, F.C., 1992. Proceedings of the Third Annual International High-level Radioactive Waste Management Conference, vol. 1, Las Vegas, NV. American Nuclear Society, La Grange Park, IL, pp. 891-989] and suggest that fast flow in fractures with minimal fracture-matrix interaction may comprise a substantial proportion of the total infiltration through Yucca Mountain. Mixing calculations suggest that bomb-pulse tritium measurements, in general, represent the tail end of travel times for thermonuclear-test-era (bomb-pulse) infiltration. The data analysis shows that bomb-pulse tritium and 36Cl measurements are correlated with discrete features such as horizontal fractures and areas where lateral flow may occur. The results presented here imply that fast flow in fractures may be ubiquitous at Yucca Mountain, occurring when transient infiltration (storms) generates flow in the connected fracture network.

  6. Tritium and 36Cl as constraints on fast fracture flow and percolation flux in the unsaturated zone at Yucca Mountain.

    PubMed

    Guerin, M

    2001-10-01

    An analysis of tritium and 36Cl data collected at Yucca Mountain, Nevada suggests that fracture flow may occur at high velocities through the thick unsaturated zone. The mechanisms and extent of this "fast flow" in fractures at Yucca Mountain are investigated with data analysis, mixing models and several one-dimensional modeling scenarios. The model results and data analysis provide evidence substantiating the weeps model [Gauthier, J.H., Wilson, M.L., Lauffer, F.C., 1992. Proceedings of the Third Annual International High-level Radioactive Waste Management Conference, vol. 1, Las Vegas, NV. American Nuclear Society, La Grange Park, IL, pp. 891-989] and suggest that fast flow in fractures with minimal fracture-matrix interaction may comprise a substantial proportion of the total infiltration through Yucca Mountain. Mixing calculations suggest that bomb-pulse tritium measurements, in general, represent the tail end of travel times for thermonuclear-test-era (bomb-pulse) infiltration. The data analysis shows that bomb-pulse tritium and 36Cl measurements are correlated with discrete features such as horizontal fractures and areas where lateral flow may occur. The results presented here imply that fast flow in fractures may be ubiquitous at Yucca Mountain, occurring when transient infiltration (storms) generates flow in the connected fracture network. PMID:11588829

  7. Tritium and 36Cl as constraints on fast fracture flow and percolation flux in the unsaturated zone at Yucca Mountain.

    PubMed

    Guerin, M

    2001-10-01

    An analysis of tritium and 36Cl data collected at Yucca Mountain, Nevada suggests that fracture flow may occur at high velocities through the thick unsaturated zone. The mechanisms and extent of this "fast flow" in fractures at Yucca Mountain are investigated with data analysis, mixing models and several one-dimensional modeling scenarios. The model results and data analysis provide evidence substantiating the weeps model [Gauthier, J.H., Wilson, M.L., Lauffer, F.C., 1992. Proceedings of the Third Annual International High-level Radioactive Waste Management Conference, vol. 1, Las Vegas, NV. American Nuclear Society, La Grange Park, IL, pp. 891-989] and suggest that fast flow in fractures with minimal fracture-matrix interaction may comprise a substantial proportion of the total infiltration through Yucca Mountain. Mixing calculations suggest that bomb-pulse tritium measurements, in general, represent the tail end of travel times for thermonuclear-test-era (bomb-pulse) infiltration. The data analysis shows that bomb-pulse tritium and 36Cl measurements are correlated with discrete features such as horizontal fractures and areas where lateral flow may occur. The results presented here imply that fast flow in fractures may be ubiquitous at Yucca Mountain, occurring when transient infiltration (storms) generates flow in the connected fracture network.

  8. HETEROGENEOUS DISTRIBUTION OF {sup 26}Al AT THE BIRTH OF THE SOLAR SYSTEM

    SciTech Connect

    Makide, Kentaro; Nagashima, Kazuhide; Krot, Alexander N.; Huss, Gary R.; Ciesla, Fred J.; Yang, Le; Hellebrand, Eric; Gaidos, Eric

    2011-06-01

    It is believed that {sup 26}Al, a short-lived (t{sub 1/2} = 0.73 Ma) and now extinct radionuclide, was uniformly distributed in the nascent solar system (SS) with the initial {sup 26}Al/{sup 27}Al ratio of {approx}5.2 x 10{sup -5}, suggesting an external, stellar origin rather than local, solar source. However, the stellar source of {sup 26}Al and the manner in which it was injected into the SS remain controversial: the {sup 26}Al could have been produced by an asymptotic giant branch star, a supernova, or a Wolf-Rayet star and injected either into the protosolar molecular cloud, protosolar cloud core, or protoplanetary disk. Corundum (Al{sub 2}O{sub 3}) is predicted to be the first condensate from a cooling gas of solar composition. Here we show that micron-sized corundum condensates from {sup 16}O-rich ({Delta}{sup 17}O {approx} -25 per mille ) gas of solar composition recorded heterogeneous distribution of {sup 26}Al at the birth of the SS: the inferred initial {sup 26}Al/{sup 27}Al ratio ranges from {approx}6.5x10{sup -5} to <2x10{sup -6}; 52% of corundum grains measured are {sup 26}Al-poor. Abundant {sup 26}Al-poor, {sup 16}O-rich refractory objects include grossite- and hibonite-rich calcium-aluminum-rich inclusions (CAIs) in CH (high metal abundance and high iron concentration) chondrites, platy hibonite crystals in CM (Mighei-like) chondrites, and CAIs with fractionation and unidentified nuclear effects CAIs chondrites. Considering the apparently early and short duration (<0.3 Ma) of condensation of refractory {sup 16}O-rich solids in the SS, we infer that {sup 26}Al was injected into the collapsing protosolar molecular cloud and later homogenized in the protoplanetary disk. The apparent lack of correlation between {sup 26}Al abundance and O-isotope composition of corundum grains constrains the stellar source of {sup 26}Al in the SS.

  9. {sup 26}Al IN THE EARLY SOLAR SYSTEM: NOT SO UNUSUAL AFTER ALL

    SciTech Connect

    Jura, M.; Xu, S.; Young, E. D. E-mail: sxu@astro.ucla.edu

    2013-10-01

    Recently acquired evidence shows that extrasolar asteroids exhibit over a factor of 100 variation in the iron to aluminum abundance ratio. This large range likely is a consequence of igneous differentiation that resulted from heating produced by radioactive decay of {sup 26}Al with an abundance comparable to that in the solar system's protoplanetary disk at birth. If so, the conventional view that our solar system began with an unusually high amount of {sup 26}Al should be discarded.

  10. 26Al- 26Mg and 207Pb- 206Pb systematics of Allende CAIs: Canonical solar initial 26Al/ 27Al ratio reinstated

    NASA Astrophysics Data System (ADS)

    Jacobsen, Benjamin; Yin, Qing-zhu; Moynier, Frederic; Amelin, Yuri; Krot, Alexander N.; Nagashima, Kazuhide; Hutcheon, Ian D.; Palme, Herbert

    2008-07-01

    The precise knowledge of the initial 26Al/ 27Al ratio [( 26Al/ 27Al) 0] is crucial if we are to use the very first solid objects formed in our Solar System, calcium-aluminum-rich inclusions (CAIs) as the "time zero" age-anchor and guide future work with other short-lived radio-chronometers in the early Solar System, as well as determining the inventory of heat budgets from radioactivities for early planetary differentiation. New high-precision multi-collector inductively-coupled plasma mass spectrometry (MC-ICP-MS) measurements of 27Al/ 24Mg ratios and Mg-isotopic compositions of nine whole-rock CAIs (six mineralogically characterized fragments and three micro-drilled inclusions) from the CV carbonaceous chondrite, Allende yield a well-defined 26Al- 26Mg fossil isochron with an ( 26Al/ 27Al) 0 of (5.23 ± 0.13) × 10 - 5 . Internal mineral isochrons obtained for three of these CAIs ( A44A, AJEF, and A43) are consistent with the whole-rock CAI isochron. The mineral isochron of AJEF with ( 26Al/ 27Al) 0 = (4.96 ± 0.25) × 10 - 5 , anchored to our precisely determined absolute 207Pb- 206Pb age of 4567.60 ± 0.36 Ma for the same mineral separates, reinstate the "canonical" ( 26Al/ 27Al) 0 of 5 × 10 - 5 for the early Solar System. The uncertainty in ( 26Al/ 27Al) 0 corresponds to a maximum time span of ± 20 Ka (thousand years), suggesting that the Allende CAI formation events were culminated within this time span. Although all Allende CAIs studied experienced multistage formation history, including melting and evaporation in the solar nebula and post-crystallization alteration likely on the asteroidal parent body, the 26Al- 26Mg and U-Pb-isotopic systematics of the mineral separates and bulk CAIs behaved largely as closed-system since their formation. Our data do not support the "supra-canonical" 26Al/ 27Al ratio of individual minerals or their mixtures in CV CAIs, suggesting that the supra-canonical 26Al/ 27Al ratio in the CV CAIs may have resulted from post

  11. 14C tebuconazole degradation in Colombian soils.

    PubMed

    Mosquera, C S; Martínez, M J; Guerrero, J A

    2010-01-01

    Tebuconazole is a fungicide used on onion crops (Allium Fistulosum L) in Colombia. Persistence of pesticides in soils is characterized by the half-life (DT50), which is influenced by their chemical structure, the physical and chemical properties of the soil and the previous soil history. Based on its structural and chemical properties, tebuconazole should be expected to be relatively persistent in soils. Laboratory incubation studies were conducted to evaluate persistence and bond residues of 14C tebuconazole in three soils, two inceptisol (I) and one histosol (H). Textural classifications were: loam (101), loamy sand (102) and loam (H03), respectively. Data obtained followed a first-order degradation kinetics (R2 > or = 0.899) with DT50 values between 158 and 198 days. The production of 14CO2 from the 14C-ring-labelled test chemicals was very low and increased slightly during 63 days in all cases. The methanol extractable 14C-residues were higher than aqueous ones and both decreased over incubation time for the three soils. The formation of bound 14C-residues increased with time and final values were 11.3; 5.55 and 7.87% for 101, 102 and H03 respectively. Soil 101 showed the lowest mineralization rate and the highest bound residues formation, which might be explained by the clay fraction content. In contrast, an inverse behavior was found for soils 102 and H03, these results might be explained by the higher soil organic carbon content. PMID:21542480

  12. 14C tebuconazole degradation in Colombian soils.

    PubMed

    Mosquera, C S; Martínez, M J; Guerrero, J A

    2010-01-01

    Tebuconazole is a fungicide used on onion crops (Allium Fistulosum L) in Colombia. Persistence of pesticides in soils is characterized by the half-life (DT50), which is influenced by their chemical structure, the physical and chemical properties of the soil and the previous soil history. Based on its structural and chemical properties, tebuconazole should be expected to be relatively persistent in soils. Laboratory incubation studies were conducted to evaluate persistence and bond residues of 14C tebuconazole in three soils, two inceptisol (I) and one histosol (H). Textural classifications were: loam (101), loamy sand (102) and loam (H03), respectively. Data obtained followed a first-order degradation kinetics (R2 > or = 0.899) with DT50 values between 158 and 198 days. The production of 14CO2 from the 14C-ring-labelled test chemicals was very low and increased slightly during 63 days in all cases. The methanol extractable 14C-residues were higher than aqueous ones and both decreased over incubation time for the three soils. The formation of bound 14C-residues increased with time and final values were 11.3; 5.55 and 7.87% for 101, 102 and H03 respectively. Soil 101 showed the lowest mineralization rate and the highest bound residues formation, which might be explained by the clay fraction content. In contrast, an inverse behavior was found for soils 102 and H03, these results might be explained by the higher soil organic carbon content.

  13. Millennial strain partitioning and fault interaction revealed by 36Cl cosmogenic nuclide datasets from Abruzzo, Central Italy

    NASA Astrophysics Data System (ADS)

    Gregory, L. C.; Phillips, R. J.; Roberts, G.; Cowie, P. A.; Shanks, R. P.; McCaffrey, K. J. W.; Wedmore, L. N. J.; Zijerveld, L.

    2015-12-01

    In zones of distributed continental faulting, it is critical to understand how slip is partitioned onto brittle structures over both long-term millennial time scales and shorter-term individual earthquake cycles. The comparison of slip distributions on different timescales is challenging due to earthquake repeat-times being longer or similar to historical earthquake records, and a paucity of data on fault activity covering millennial to Quaternary scales in detail. Cosmogenic isotope analyses from bedrock fault scarps have the potential to bridge the gap, as these datasets track the exposure of fault planes due to earthquakes with better-than-millennial resolution. In this presentation, we will use an extensive 36Cl dataset to characterise late Holocene activity across a complicated network of normal faults in Abruzzo, Italy, comparing the most recent fault behaviour with the historical earthquake record in the region. Extensional faulting in Abruzzo has produced scarps of exposed bedrock limestone fault planes that have been preserved since the last glacial maximum (LGM). 36Cl accumulates in bedrock fault scarps as the plane is progressively exhumed by earthquakes and thus the concentration of 36Cl measured up the fault plane reflects the rate and patterns of slip. In this presentation, we will focus on the most recent record, revealed at the base of the fault. Utilising new Bayesian modelling techniques on new and previously collected data, we compare evidence for this most recent period of slip (over the last several thousands of years) across 5-6 fault zones located across strike from each other. Each sampling site is carefully characterised using LiDAR and GPR. We demonstrate that the rate of slip on individual fault strands varies significantly, between having periods of accelerated slip to relative quiescence. Where data is compared between across-strike fault zones and with the historical catalogue, it appears that slip is partitioned such that one fault

  14. Heating and melting of small icy satellites by the decay of 26Al

    NASA Technical Reports Server (NTRS)

    Prialnik, D.; Bar-Nun, A.; Owen, T. (Principal Investigator)

    1990-01-01

    We study the effect of radiogenic heating due to 26Al on the thermal evolution of small icy satellites. Our object is to find the extent of internal melting as a function of the satellite radius and of the initial 26Al abundance. The implicit assumption, based on observations of young stars, is that planet and satellite accretion occurred on a time scale of approximately 10(6) yr (comparable with the lifetime of 26Al). The icy satellites are modeled as spheres of initially amorphous ice, with chondritic abundances of 40K, 232Th, 235U, 238U, corresponding to an ice/dust mass ratio of 1. Evolutionary calculations are carried out, spanning 4.5 x 10(9) yr, for different combinations of the two free parameters. Heat transfer by subsolidus convection is neglected for these small satellites. Our main conclusion is that the initial 26Al abundance capable of melting icy bodies of satellite size to a significant extent is more than 10 times lower than that prevailing in the interstellar medium (or that inferred from the Ca-Al rich inclusions of the Allende meteorite, approximately 7 x 10(-7) by mass). We find, for example, that an initial 26Al mass fraction of approximately 4 x 10(-8) is sufficient for melting almost completely icy spheres with radii of 800 km, typical of the larger icy planetary satellites. We also find that for any given 26Al abundance, there is a narrow range of radii below which only marginal melting occurs and above which most of the ice melts (and refreezes later). Since extensive melting may have important consequences, such as differentiation, gas release, and volcanic activity, the effect of 26Al should be included in future studies of satellite interiors.

  15. Early accretion of protoplanets inferred from a reduced inner solar system 26Al inventory

    NASA Astrophysics Data System (ADS)

    Schiller, Martin; Connelly, James N.; Glad, Aslaug C.; Mikouchi, Takashi; Bizzarro, Martin

    2015-06-01

    The mechanisms and timescales of accretion of 10-1000 km sized planetesimals, the building blocks of planets, are not yet well understood. With planetesimal melting predominantly driven by the decay of the short-lived radionuclide 26Al (26Al→26Mg; t1/2 = 0.73 Ma), its initial abundance determines the permissible timeframe of planetesimal-scale melting and its subsequent cooling history. Currently, precise knowledge about the initial 26Al abundance [(26Al/27Al)0] exists only for the oldest known solids, calcium aluminum-rich inclusions (CAIs) - the so-called canonical value. We have determined the 26Al/27Al of three angrite meteorites, D'Orbigny, Sahara 99555 and NWA 1670, at their time of crystallization, which corresponds to (3.98 ± 0.15) ×10-7, (3.64 ± 0.18) ×10-7, and (5.92 ± 0.59) ×10-7, respectively. Combined with a newly determined absolute U-corrected Pb-Pb age for NWA 1670 of 4564.39 ± 0.24 Ma and published U-corrected Pb-Pb ages for the other two angrites, this allows us to calculate an initial (26Al/27Al)0 of (1.33-0.18+0.21) ×10-5 for the angrite parent body (APB) precursor material at the time of CAI formation, a value four times lower than the accepted canonical value of 5.25 ×10-5. Based on their similar 54Cr/52Cr ratios, most inner solar system materials likely accreted from material containing a similar 26Al/27Al ratio as the APB precursor at the time of CAI formation. To satisfy the abundant evidence for widespread planetesimal differentiation, the subcanonical 26Al budget requires that differentiated planetesimals, and hence protoplanets, accreted rapidly within 0.25 ± 0.15 Ma of the formation of canonical CAIs.

  16. Heating and melting of small icy satellites by the decay of 26Al.

    PubMed

    Prialnik, D; Bar-Nun, A

    1990-05-20

    We study the effect of radiogenic heating due to 26Al on the thermal evolution of small icy satellites. Our object is to find the extent of internal melting as a function of the satellite radius and of the initial 26Al abundance. The implicit assumption, based on observations of young stars, is that planet and satellite accretion occurred on a time scale of approximately 10(6) yr (comparable with the lifetime of 26Al). The icy satellites are modeled as spheres of initially amorphous ice, with chondritic abundances of 40K, 232Th, 235U, 238U, corresponding to an ice/dust mass ratio of 1. Evolutionary calculations are carried out, spanning 4.5 x 10(9) yr, for different combinations of the two free parameters. Heat transfer by subsolidus convection is neglected for these small satellites. Our main conclusion is that the initial 26Al abundance capable of melting icy bodies of satellite size to a significant extent is more than 10 times lower than that prevailing in the interstellar medium (or that inferred from the Ca-Al rich inclusions of the Allende meteorite, approximately 7 x 10(-7) by mass). We find, for example, that an initial 26Al mass fraction of approximately 4 x 10(-8) is sufficient for melting almost completely icy spheres with radii of 800 km, typical of the larger icy planetary satellites. We also find that for any given 26Al abundance, there is a narrow range of radii below which only marginal melting occurs and above which most of the ice melts (and refreezes later). Since extensive melting may have important consequences, such as differentiation, gas release, and volcanic activity, the effect of 26Al should be included in future studies of satellite interiors.

  17. A comparison of groundwater dating with 81Kr, 36Cl and 4He in four wells of the Great Artesian Basin, Australia

    NASA Astrophysics Data System (ADS)

    Lehmann, B. E.; Love, A.; Purtschert, R.; Collon, P.; Loosli, H. H.; Kutschera, W.; Beyerle, U.; Aeschbach-Hertig, W.; Kipfer, R.; Frape, S. K.; Herczeg, A.; Moran, J.; Tolstikhin, I. N.; Gröning, M.

    2003-06-01

    The isotopic ratios 81Kr/Kr and 36Cl/Cl and the 4He concentrations measured in groundwater from four artesian wells in the western part of the Great Artesian Basin (GAB) in Australia are discussed. Based on radioactive decay along a water flow path the 81Kr/Kr ratios are directly converted to groundwater residence times. Results are in a range of 225-400 kyr with error bars in the order of 15% primarily due to counting statistics in the cyclotron accelerator mass spectrometer measurement. Additional uncertainties from subsurface production and/or exchange with stagnant porewaters in the confining shales appear to be of the same order of magnitude. These 81Kr ages are then used to calibrate the 36Cl and the 4He dating methods. Based on elemental analyses of rock samples from the sandstone aquifer as well as from the confining Bulldog shale the in situ flux of thermal neutrons and the corresponding 3He/ 4He and 36Cl/Cl ratios are calculated. From a comparison of: (i) the 3He/ 4He ratios measured in the groundwater samples with the calculated in situ ratios in rocks and (ii) the measured δ 37Cl ratios with the 4He concentrations measured in groundwater it is concluded that both helium and chloride are most likely added to the aquifer from sources in the stagnant porewaters of the confining shale by diffusion and/or mixing. Based on this 'working hypothesis' the 36Cl transport equation in groundwater is solved taking into account: (i) radioactive decay, (ii) subsurface production in the sandstone aquifer (with an in situ 36Cl/Cl ratio of 6×10 -15) and (iii) addition of chloride from a source in the confining shale (with a 36Cl/Cl ratio of 13×10 -15). Lacking better information it is assumed that the chloride concentration increased linearly with time from an (unknown) initial value Ci to its measured present value C= Ci+ Ca, where Ca represents the (unknown) amount of chloride added from subsurface sources. Using the 81Kr ages of the four groundwater samples and a

  18. Depth-dependence of the production rate of in-situ 14-C in quartz

    NASA Astrophysics Data System (ADS)

    Lupker, Maarten; Hippe, Kristina; Kober, Florian; Wacker, Lukas; Braucher, Régis; Bourlès, Didier; Vidal Romani, Juan; Wieler, Rainer

    2013-04-01

    Terrestrial cosmogenic nuclides provide a means to document and quantify the rates of changes of the landscape at the Earth's surface and have therefore received an increasing attention over the past decade. The short lived in-situ produced 14-C has recently emerged as a complement to other longer lived cosmogenic nuclides such as 10-Be or 26-Al. The short half-life (5730 yr) of 14-C makes it suitable to investigate surface processes such as denudation rates or sediment residence times on ka scales. The wide application of in-situ 14-C for quantitative studies is however bound to the proper calibration of its production mechanisms and rates. As other cosmogenic nuclides, 14-C is produced at the Earth's surface by nuclear reactions with incoming neutrons and muons. The production rate of 14-C has been determined for quartz exposed at the surface where neutrons dominate the overall production [1]. At depth, however, the muon production pathway starts to dominate, because the mean attenuation length of muons is considerably longer than that of neutrons. So far, the muon derived in-situ 14-C production rate is solely based on theoretical and experimental work [2] that has not been tested on natural objects. We measured the 14-C concentration in quartz along the Leymon High core (42.065 N, 7.014 E - alt: 1277 m; Northwestern Spain) using the ETH 14-C extraction line [3] and the MICADAS gas source AMS [4]. This core has been drilled down to 20 m in a quartz dyke and has already been used to refine the depth-dependent production rate of 10-Be and 26-Al [5]. Our results on 14 samples of this core spanning a depth range from 1 to 1545 cm allow us to estimate the muogenic contribution to the overall 14-C concentrations measured along the core. This data set yields a local surface muon production rate of 3.9 (+3.1, -0.6) at.g-1.yr-1, which translates into a surface Sea Level High Latitude muon production rate of 2.2 (+1.8, -0.4) at.g-1.yr-1. This is ca. 17 % of the SLHL

  19. Measurement of 26Al in Iron Meteorites by Thermal Ionization Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Langellier, C.; Birck, J. L.; Allegre, C. J.

    1992-07-01

    We report here the measurement of ^26Al by thermal ionization mass spectrometry in iron meteorites. Nuclides produced by the interaction of galactic cosmic rays with meteoritic bodies are widely used to reconstruct the parental history of meteorites and also to address the problem of constancy of cosmic rays in the past. In iron meteorites the half life of ^26Al is much shorter than the exposure age and saturation is reached. Its concentration is then directly related to the preatmospheric shielding of the analyzed sample. It can be also used together, with other short-lived nuclides, to calculate the terrestrial residence time for found meteorites. Natural contents of ^26Al in iron meteorites are very small (a few dpm per kg) and have been measured earlier by counting techniques and AMS. For thermal ionization the difficulty resides mostly in the measurement of the ^26Al/^27Al ratio. ^27Al may be contained in the sample and also is introduced by the chemical separation. ^27Al beams of 10^-11 A are readily obtained with a few ng of aluminium and are measured on a standard faraday cup. ^26Al was measured on a low background electron multiplier operated in the ion counter mode. ^27Al content was measured by isotope dilution using a ^26Al spike. The ^26Al ion beam can be interfered by traces of ^26Mg. Usually the ^26Mg background could be brought lower than 10^-9 relative to ^27Al. This is sufficient for the present experiment. No organic interference was present at the same level. The abundance sensitivity stemming from the ^27Al beam on mass 26 is 3 10^-9. Results: Samples sizes for this study range from 100 to 300 mg of iron. Ratios are measured with a precision of about 1% thereby leading to a final ^26Al content with an accuracy around 2%. Two meteorites were investigated so far: Grant and Canyon Diablo. Grant is one of the best documented meteorites with regard to spallation effects. The result on Grant is an agreement with literature AMS data (Graf et al., 1987

  20. 26Al production: The Allende meteorite (Chihuahua) stellar nucleosynthesis and solar models

    NASA Astrophysics Data System (ADS)

    Araujo-Escalona, V.; Andrade, E.; Barrón-Palos, L.; Canto, C.; Favela, F.; Huerta, A.; de Lucio, O.; Ortiz, M. E.; Solís, C.; Chávez, E.

    2015-07-01

    In 1969 a meteorite fell near the small town of Allende, state of Chihuahua in the north of Mexico. Its study yielded information that changed the current understanding of the solar model. In particular traces of 26Al were found. Abundances of that isotope had been seen in the universe and were related to regions of active heavy nucleosynthesis. Its presence on the solar system was unexpected. It is now understood that cosmic rays induce nuclear reactions on materials to produce 26Al, on Earth this is well known and it is the basis of many environmental studies, so it is not only the product of some high metalicity star collapse. Taking advantage of the recently reinforced laboratory infrastructure of the Instituto de Física, at UNAM in Mexico City, we proposed to measure the cross section for 26Al production via some of the most likely reactions, from the nuclear physics point of view (highest Q-values). In this paper the study of the 28Si(d,α)26 Al nuclear reaction is shown. A target is prepared by a mixture of silicon and aluminum powders. It is irradiated with a deuteron beam (≈1 µA current) at the MV CN-Van de Graaff accelerator laboratory. The number of projectiles is deduced by Rutherford Backscattering Spectrometry (RBS). The produced 26Al nuclei are then counted at the Accelerator Mass Spectrometry Laboratory.

  1. {sup 26}Al production: The Allende meteorite (Chihuahua) stellar nucleosynthesis and solar models

    SciTech Connect

    Araujo-Escalona, V.; Andrade, E.; Barrón-Palos, L.; Canto, C.; Favela, F.; Huerta, A.; Lucio, O. de; Ortiz, M. E.; Solís, C.; Chávez, E.

    2015-07-23

    In 1969 a meteorite fell near the small town of Allende, state of Chihuahua in the north of Mexico. Its study yielded information that changed the current understanding of the solar model. In particular traces of {sup 26}Al were found. Abundances of that isotope had been seen in the universe and were related to regions of active heavy nucleosynthesis. Its presence on the solar system was unexpected. It is now understood that cosmic rays induce nuclear reactions on materials to produce {sup 26}Al, on Earth this is well known and it is the basis of many environmental studies, so it is not only the product of some high metalicity star collapse. Taking advantage of the recently reinforced laboratory infrastructure of the Instituto de Física, at UNAM in Mexico City, we proposed to measure the cross section for {sup 26}Al production via some of the most likely reactions, from the nuclear physics point of view (highest Q-values). In this paper the study of the {sup 28}Si(d,α){sup 26} Al nuclear reaction is shown. A target is prepared by a mixture of silicon and aluminum powders. It is irradiated with a deuteron beam (≈1 µA current) at the MV CN-Van de Graaff accelerator laboratory. The number of projectiles is deduced by Rutherford Backscattering Spectrometry (RBS). The produced {sup 26}Al nuclei are then counted at the Accelerator Mass Spectrometry Laboratory.

  2. Improvement of the 36Cl-AMS system at MALT using a Monte Carlo ion-trajectory simulation in a gas-filled magnet

    NASA Astrophysics Data System (ADS)

    Aze, Takahiro; Matsuzaki, Hiroyuki; Matsumura, Hiroshi; Nagai, Hisao; Fujimura, Masatsugu; Noguchi, Mayumi; Hongo, Yayoi; Yokoyama, Yusuke

    2007-06-01

    We developed and experimentally confirmed a Monte Carlo simulation code to describe the trajectories of 36Cl and 36S ions in a gas-filled magnet (GFM) at the MALT, the University of Tokyo. The simulation revealed that the central trajectories of the ions in the GFM are almost spiral and most of the 36S ions collided with the interior wall of the GFM. Based on this property of the trajectories, we have found a more advantageous condition for suppressing 36S. As a result, the background level of the 36Cl/Cl ratio was lowered to 10-15.

  3. Heterogeneous distribution of 26Al at the birth of the solar system: Evidence from refractory grains and inclusions

    NASA Astrophysics Data System (ADS)

    Krot, A. N.; Makide, K.; Nagashima, K.; Huss, G. R.; Ogliore, R. C.; Ciesla, F. J.; Yang, L.; Hellebrand, E.; Gaidos, E.

    2012-12-01

    Abstract-We review recent results on O- and Mg-isotope compositions of refractory grains (corundum, hibonite) and calcium, aluminum-rich inclusions (CAIs) from unequilibrated ordinary and carbonaceous chondrites. We show that these refractory objects originated in the presence of nebular gas enriched in 16O to varying degrees relative to the standard mean ocean water value: the Δ17OSMOW value ranges from approximately -16‰ to -35‰, and recorded heterogeneous distribution of <span class="hlt">26</span><span class="hlt">Al</span> in their formation region: the inferred (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 ranges from approximately 6.5 × 10-5 to <2 × 10-6. There is no correlation between O- and Mg-isotope compositions of the refractory objects: <span class="hlt">26</span><span class="hlt">Al</span>-rich and <span class="hlt">26</span><span class="hlt">Al</span>-poor refractory objects have similar O-isotope compositions. We suggest that <span class="hlt">26</span><span class="hlt">Al</span> was injected into the <span class="hlt">26</span><span class="hlt">Al</span>-poor collapsing protosolar molecular cloud core, possibly by a wind from a neighboring massive star, and was later homogenized in the protoplanetary disk by radial mixing, possibly at the canonical value of <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratio (approximately 5 × 10-5). The <span class="hlt">26</span><span class="hlt">Al</span>-rich and <span class="hlt">26</span><span class="hlt">Al</span>-poor refractory grains and inclusions represent different generations of refractory objects, which formed prior to and during the injection and homogenization of <span class="hlt">26</span><span class="hlt">Al</span>. Thus, the duration of formation of refractory grains and CAIs cannot be inferred from their <span class="hlt">26</span><span class="hlt">Al</span>-26Mg systematics, and the canonical (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 does not represent the initial abundance of <span class="hlt">26</span><span class="hlt">Al</span> in the solar system; instead, it may or may not represent the average abundance of <span class="hlt">26</span><span class="hlt">Al</span> in the fully formed disk. The latter depends on the formation time of CAIs with the canonical <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratio relative to the timing of complete delivery of stellar <span class="hlt">26</span><span class="hlt">Al</span> to the solar system, and the degree of its subsequent homogenization in the disk. The injection of material containing <span class="hlt">26</span><span class="hlt">Al</span> resulted in no observable changes in O-isotope composition of the solar system. Instead, the variations in O-isotope compositions between individual</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.192..279H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.192..279H"><span id="translatedtitle">Characterization of a diffusion-dominant system using chloride and chlorine isotopes (<span class="hlt">36</span><span class="hlt">Cl</span>, 37Cl) for the confining layer of the Great Artesian Basin, Australia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hasegawa, Takuma; Nakata, Kotaro; Mahara, Yasunori; Habermehl, M. A.; Oyama, Takahiro; Higashihara, Tomohiro</p> <p>2016-11-01</p> <p>The Great Artesian Basin (GAB), Australia, one of the largest confined aquifer systems in the world, attracts great attention for groundwater dating. However, there is little information about the confining layers. Therefore, core drilling investigations were conducted to characterize the main confining layer using chloride (Cl) and chlorine isotopes (<span class="hlt">36</span><span class="hlt">Cl</span>, 37Cl) at Marree (South Australia) and Richmond (Queensland), which are near the discharge and recharge areas in the GAB, respectively. Pore water samples were collected from rock cores by squeezing and leaching. The Cl concentration, <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratio, and δ37Cl value in the confining layer decreased with depth at both Marree and Richmond. The <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratios at the shallower part of the confining layer are significantly higher than the in situ secular equilibrium (<span class="hlt">36</span><span class="hlt">Cl</span>/Clse) calculated from the chemical compositions of the rock. The <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratio logarithmically decreased with depth. The calculated <span class="hlt">36</span><span class="hlt">Cl</span>/Clse is equivalent to the lowest <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratio at Richmond. In contrast, the <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratios at Marree are higher than the calculated <span class="hlt">36</span><span class="hlt">Cl</span>/Clse. The <span class="hlt">36</span><span class="hlt">Cl</span>/Clse was reached at Richmond, but not at Marree. This probably reflects the transport time due to the difference in diffusion coefficients. The δ37Cl value becomes more negative toward the deeper levels, reaching -4.5‰ and -6.1‰ at Marree and Richmond, respectively. These results suggest that the Cl is of meteoric origin and is transported by diffusion in the confining layer. Analytical simulations using diffusion equations were conducted to reproduce excess <span class="hlt">36</span><span class="hlt">Cl</span> (36Clex), Cl, and δ37Cl. The 36Clex profile, which logarithmically decreased with depth, was reproduced by steady-state diffusion equations with radioactive decay, and the diffusion coefficients derived from the 36Clex profile were equivalent to those from the laboratory experiments. A grid-search simulation using an unsteady-state diffusion equation was conducted to reproduce the Cl and δ37Cl</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007NIMPB.259..625H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007NIMPB.259..625H"><span id="translatedtitle">Measurement of <span class="hlt">26</span><span class="hlt">Al</span> in Antarctic ice with the MALT-AMS system at the University of Tokyo</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Horiuchi, Kazuho; Matsuzaki, Hiroyuki; Ohta, Aoi; Shibata, Yasuyuki; Motoyama, Hideaki</p> <p>2007-06-01</p> <p>We have attempted to determine the <span class="hlt">26</span><span class="hlt">Al</span> concentration of Antarctic ice sampled from the vicinity of the Dome Fuji Research Station using accelerator mass spectrometry (AMS) at MALT (MicroAnalysis Laboratory, Tandem accelerator) of the University of Tokyo. Because the expected concentration of <span class="hlt">26</span><span class="hlt">Al</span> in ice is very low, our standard procedure for the AMS measurement was re-examined and refined. The observed <span class="hlt">26</span><span class="hlt">Al</span> concentration ranged between 160 and 210 atoms g-1. The averaged value of the <span class="hlt">26</span><span class="hlt">Al</span>/10Be ratio from two samples was 1.75 ± 0.19 × 10-3, which agrees well with recently reported values for the meteoric <span class="hlt">26</span><span class="hlt">Al</span>/10Be ratio from Antarctic ice and air filter residues. This result implies the possibility of future <span class="hlt">26</span><span class="hlt">Al</span>/10Be dating of old Antarctic ice.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6005501','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6005501"><span id="translatedtitle">Bioconversion of. cap alpha. -(/sup <span class="hlt">14</span>/<span class="hlt">C</span>)Zearalenol and. beta. -(/sup <span class="hlt">14</span>/<span class="hlt">C</span>)Zearalenol into (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)Zearalenone by Fusarium roseum Gibbosum</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Richardson, K.E.; Hagler, W.M. Jr.; Hamilton, P.B.</p> <p>1984-06-01</p> <p>Cultures of Fusarium roseum Gibbosum on rice were treated with (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)zearalenone, ..cap alpha..-(/sup <span class="hlt">14</span>/<span class="hlt">C</span>)zearalenol, or ..beta..-(/sup <span class="hlt">14</span>/<span class="hlt">C</span>)zearalenol to determine whether a precursor-product relationship exists among these closely related fungal metabolites. Culture extracts were purified by silica gel column chromatography and fractionated by high-pressure liquid chromatography, and the level of radioactivity was determined. Within 7 days, the ..beta..-(/sup <span class="hlt">14</span>/<span class="hlt">C</span>)zearalenol was converted to zearalenone, and no residual ..beta..-(/sup <span class="hlt">14</span>/<span class="hlt">C</span>)zearalenol was detectable. Most of the ..cap alpha..-(/sup <span class="hlt">14</span>/<span class="hlt">C</span>)zearalenol added was also converted into zearalenone within 14 days. In cultures treated with (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)zearalenone, no radioactivity was noted in any other components.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011NIMPB.269.3171M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011NIMPB.269.3171M"><span id="translatedtitle">Forensic applications of <span class="hlt">14</span><span class="hlt">C</span> at CIRCE</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marzaioli, F.; Fiumano, V.; Capano, M.; Passariello, I.; Cesare, N. De.; Terrasi, F.</p> <p>2011-12-01</p> <p>The decreasing trend of the radiocarbon pulse produced during the atmospheric tests of nuclear weapons (bomb-carbon) coupled with high sensitivity accelerator mass spectrometry (AMS) measurements, drastically increased the precision of radiocarbon age determinations since the second part of the sixties, allowing the application of radiocarbon AMS to a wide range of studies previously not directly involving conventional radiocarbon dating (i.e. food authenticity, forensic, biochemistry). In the framework of authenticity evaluation of artworks, high precision radiocarbon ( <span class="hlt">14</span><span class="hlt">C</span>) AMS measurements (Δ R/ R < 0.3%) reduce the conventional uncertainty of the dating to few decades, allowing precise age estimation of materials containing carbon (C). The Centre for Isotopic Research on Cultural and Environmental heritage (CIRCE) during its activity on AMS <span class="hlt">14</span><span class="hlt">C</span> dating achieved high precision measurements opening the opportunity to these kinds of applications. This paper presents the main results obtained from radiocarbon measurements on a set of bone samples analyzed for the determination of the post-mortem interval in the framework of an unsolved case investigated by the Rome prosecutor office. The chronological characterization of the wooden support of the "Acerenza portrait" is also presented with the aim to evaluate its age and to further investigate the possibility to attribute this artwork to Leonardo da Vinci. Bomb- <span class="hlt">14</span><span class="hlt">C</span> dating on the lipid and collagen fractions of bones allows the evaluation of the year of the death of the individuals by means of ad hoc calibration data sheet with the typical few years precision and difference between collagen apparent age and the year of death appeared in agreement with the age of one individual estimated by dating of tooth collagen. Conventional radiocarbon dating on both wood and wood extracted cellulose leads to an estimation of the portrait wood board age (2σ) of 1459-1524 AD (57% relative probability), 1571-1631 AD interval (42</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70016363','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70016363"><span id="translatedtitle">In situ 10Be-<span class="hlt">26</span><span class="hlt">Al</span> exposure ages at Meteor Crater, Arizona</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Nishiizumi, K.; Kohl, C.P.; Shoemaker, E.M.; Arnold, J.R.; Klein, J.; Fink, D.; Middleton, R.</p> <p>1991-01-01</p> <p>A new method of dating the surface exposure of rocks from in situ production of 10Be and <span class="hlt">26</span><span class="hlt">Al</span> has been applied to determine the age of Meteor Crater, Arizona. A lower bound on the crater age of 49,200 ?? 1,700 years has been obtained by this method. ?? 1991.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4946628','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4946628"><span id="translatedtitle">Early accretion of protoplanets inferred from a reduced inner solar system <span class="hlt">26</span><span class="hlt">Al</span> inventory</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Schiller, Martin; Connelly, James N.; Glad, Aslaug C.; Mikouchi, Takashi; Bizzarro, Martin</p> <p>2016-01-01</p> <p>The mechanisms and timescales of accretion of 10–1000 km sized planetesimals, the building blocks of planets, are not yet well understood. With planetesimal melting predominantly driven by the decay of the short-lived radionuclide <span class="hlt">26</span><span class="hlt">Al</span> (26Al→26Mg; t1/2 = 0.73 Ma), its initial abundance determines the permissible timeframe of planetesimal-scale melting and its subsequent cooling history. Currently, precise knowledge about the initial <span class="hlt">26</span><span class="hlt">Al</span> abundance [(<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0] exists only for the oldest known solids, calcium aluminum-rich inclusions (CAIs) – the so-called canonical value. We have determined the <span class="hlt">26</span><span class="hlt">Al</span>/27Al of three angrite meteorites, D’Orbigny, Sahara 99555 and NWA 1670, at their time of crystallization, which corresponds to (3.98 ± 0.15)×10−7, (3.64 ± 0.18)×10−7, and (5.92 ± 0.59)×10−7, respectively. Combined with a newly determined absolute U-corrected Pb–Pb age for NWA 1670 of 4564.39 ± 0.24 Ma and published U-corrected Pb–Pb ages for the other two angrites, this allows us to calculate an initial (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 of (1.33−0.18+0.21)×10−5 for the angrite parent body (APB) precursor material at the time of CAI formation, a value four times lower than the accepted canonical value of 5.25 × 10−5. Based on their similar 54Cr/52Cr ratios, most inner solar system materials likely accreted from material containing a similar <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratio as the APB precursor at the time of CAI formation. To satisfy the abundant evidence for widespread planetesimal differentiation, the subcanonical <span class="hlt">26</span><span class="hlt">Al</span> budget requires that differentiated planetesimals, and hence protoplanets, accreted rapidly within 0.25 ± 0.15 Ma of the formation of canonical CAIs. PMID:27429474</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16151825','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16151825"><span id="translatedtitle">The Hiroshima thermal-neutron discrepancy for (<span class="hlt">36</span>)<span class="hlt">Cl</span> at large distances. Part II: Natural in situ production as a source.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nolte, Eckehart; Huber, Thomas; Rühm, Werner; Kato, Kazuo; Lazarev, Vitali; Schultz, Ludolf</p> <p>2005-10-01</p> <p>For Hiroshima, a large discrepancy between calculated and measured thermal-neutron fluences had been reported in the past, for distances to the epicenter larger than about 1,000 m. To be more specific, measured (<span class="hlt">36</span>)<span class="hlt">Cl</span> concentrations in environmental samples from Hiroshima were too large at these distances, and the ratio of measured to calculated values reached about 70, at a distance of 1,800 m. In an attempt to identify other sources that might also produce (<span class="hlt">36</span>)<span class="hlt">Cl</span> in Hiroshima samples, the role of cosmic rays and of neutrons from natural terrestrial sources was investigated. Four reaction mechanisms were taken into account: spallation reactions of the nucleonic (hadronic) component of the cosmic rays on potassium (K) and calcium (Ca) in the sample material, particle emission after nuclear capture of negative muons by K and Ca, reactions of fast-muon induced electromagnetic, and hadronic showers with K and Ca, and neutron capture reactions with (35)Cl in the sample where the neutrons originate from the above three reaction mechanisms and from uranium and thorium decay. These mechanisms are physically described and mathematically quantified. It is shown that among those parameters important for the production of (<span class="hlt">36</span>)<span class="hlt">Cl</span> in granite, the chemical composition of the sample, the depth in the quarry where the sample had initially been taken, and the erosion rate at the site of the quarry are most important. Based on these physical, chemical, and geological parameters, (<span class="hlt">36</span>)<span class="hlt">Cl</span> concentrations were calculated for different types of granite that are typical for the Hiroshima area. In samples that were of these granite types and that had not been exposed to atomic bomb(A-bomb) neutrons, the (<span class="hlt">36</span>)<span class="hlt">Cl</span> concentration was also determined experimentally by means of accelerator mass spectrometry, and good agreement was found with the calculated values. The (<span class="hlt">36</span>)<span class="hlt">Cl</span> signal due to natural in situ production was also calculated in granite samples that had been exposed to A-bomb neutrons at</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/16151825','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/16151825"><span id="translatedtitle">The Hiroshima thermal-neutron discrepancy for (<span class="hlt">36</span>)<span class="hlt">Cl</span> at large distances. Part II: Natural in situ production as a source.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nolte, Eckehart; Huber, Thomas; Rühm, Werner; Kato, Kazuo; Lazarev, Vitali; Schultz, Ludolf</p> <p>2005-10-01</p> <p>For Hiroshima, a large discrepancy between calculated and measured thermal-neutron fluences had been reported in the past, for distances to the epicenter larger than about 1,000 m. To be more specific, measured (<span class="hlt">36</span>)<span class="hlt">Cl</span> concentrations in environmental samples from Hiroshima were too large at these distances, and the ratio of measured to calculated values reached about 70, at a distance of 1,800 m. In an attempt to identify other sources that might also produce (<span class="hlt">36</span>)<span class="hlt">Cl</span> in Hiroshima samples, the role of cosmic rays and of neutrons from natural terrestrial sources was investigated. Four reaction mechanisms were taken into account: spallation reactions of the nucleonic (hadronic) component of the cosmic rays on potassium (K) and calcium (Ca) in the sample material, particle emission after nuclear capture of negative muons by K and Ca, reactions of fast-muon induced electromagnetic, and hadronic showers with K and Ca, and neutron capture reactions with (35)Cl in the sample where the neutrons originate from the above three reaction mechanisms and from uranium and thorium decay. These mechanisms are physically described and mathematically quantified. It is shown that among those parameters important for the production of (<span class="hlt">36</span>)<span class="hlt">Cl</span> in granite, the chemical composition of the sample, the depth in the quarry where the sample had initially been taken, and the erosion rate at the site of the quarry are most important. Based on these physical, chemical, and geological parameters, (<span class="hlt">36</span>)<span class="hlt">Cl</span> concentrations were calculated for different types of granite that are typical for the Hiroshima area. In samples that were of these granite types and that had not been exposed to atomic bomb(A-bomb) neutrons, the (<span class="hlt">36</span>)<span class="hlt">Cl</span> concentration was also determined experimentally by means of accelerator mass spectrometry, and good agreement was found with the calculated values. The (<span class="hlt">36</span>)<span class="hlt">Cl</span> signal due to natural in situ production was also calculated in granite samples that had been exposed to A-bomb neutrons at</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11539739','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11539739"><span id="translatedtitle">Radiogenic heating of comets by <span class="hlt">26</span><span class="hlt">Al</span> and implications for their time of formation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Prialnik, D; Bar-Nun, A; Podolak, M</p> <p>1987-08-15</p> <p>The effect of radiogenic heating on the thermal evolution of spherical icy bodies with radii 1 km < R < 100 km was investigated. The radioisotopes considered were <span class="hlt">26</span><span class="hlt">Al</span>, 40K, 232Th, 235U, and 238U. Except for the <span class="hlt">26</span><span class="hlt">Al</span> abundance, which was varied, the other initial abundances were kept fixed, at values derived from those of chondritic meteorites and corresponding to a gas-to-dust ratio of 1. The initial models were homogeneous and isothermal (To = 10 K) amorphous ice spheres, in a circular orbit at 10(4) AU from the Sun. The main object of this study was to examine the conditions under which the transition temperature from amorphous into cubic ice (Ta = 137 K) would be reached. It was shown that the influence of the short-lived radionuclide <span class="hlt">26</span><span class="hlt">Al</span> dominates the effect of other radioactive species for bodies of radii up to approximately 50 km. Consequently, if we require comets to retain their ice in amorphous form, as suggested by observations, an upper limit of approximately 4 x 10(-9) is obtained for the initial <span class="hlt">26</span><span class="hlt">Al</span> abundance in comets, a factor of 100 lower than that of the inclusions in the Allende meteorite. A lower limit for the formation time of comets may thus be derived. The possibility of a coexistence of molten cometary cores and extended amorphous ice mantles is ruled out. Larger icy spheres (R > 100 km) reached Ta even in the absence of <span class="hlt">26</span><span class="hlt">Al</span>, due to the decay of the other radionuclides. As a result, a crystalline core formed whose relative size depended on the composition assumed. Thus the outermost icy satellites in the solar system, which might have been formed of ice in the amorphous state, have probably undergone crystallization and may have exhibited eruptive activity when the gas trapped in the amorphous ice was released (e.g., Miranda).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/277041','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/277041"><span id="translatedtitle">Measurement of proton production cross sections of {sup 10}Be and {sup <span class="hlt">26</span>}<span class="hlt">Al</span> from elements found in lunar rocks</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sisterson, J.M.; Kim, K.; Englert, P.A.J.</p> <p>1996-07-01</p> <p>Cosmic rays penetrate the lunar surface and interact with the lunar rocks to produce both radionuclides and stable nuclides. Production depth profiles for long-lived radionuclides produce in lunar rocks are measured using Accelerator Mass Spectrometry (AMS). For a particular radionuclide these production depth profiles can be interpreted to give an estimate for the solar proton flux over a time period characterized by the half life of the radionuclide under study. This analysis is possible if and only if all the cross sections for the interactions of all cosmic ray particles with all elements found in lunar rocks are well known. In practice, the most important cross sections needed are the proton production cross sections, because 98% of solar cosmic rays and {similar_to}87% of galactic cosmic rays are protons. The cross sections for the production of long-lived radionuclides were very difficult to measure before the development of AMS and only in recent years has significant progress been made in determining these essential cross sections. Oxygen and silicon are major constituents of lunar rocks. We have reported already {sup <span class="hlt">14</span>}<span class="hlt">C</span> production cross sections from O and Si for proton energies 25-500 MeV, and O(p,x){sup 10}Be from 58 160 MeV[6]. Here we present new measurements for the cross sections O(p,x){sup 10}Be,O(p,x){sup 7}Be, Si(p,x){sup 7}Be,Si(p,x){sup <span class="hlt">26</span>}<span class="hlt">Al</span>, and Si(p,x){sup 22}Na from {approximately}30 - 500 MeV.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApJ...826...22K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApJ...826...22K"><span id="translatedtitle">Tracking the Distribution of <span class="hlt">26</span><span class="hlt">Al</span> and 60Fe during the Early Phases of Star and Disk Evolution</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kuffmeier, Michael; Frostholm Mogensen, Troels; Haugbølle, Troels; Bizzarro, Martin; Nordlund, Åke</p> <p>2016-07-01</p> <p>The short-lived <span class="hlt">26</span><span class="hlt">Al</span> and 60Fe radionuclides are synthesized and expelled into the interstellar medium by core-collapse supernova events. The solar system’s first solids, calcium-aluminum refractory inclusions (CAIs), contain evidence for the former presence of the <span class="hlt">26</span> <span class="hlt">Al</span> nuclide defining the canonical <span class="hlt">26</span><span class="hlt">Al</span>/27 Al ratio of ˜ 5× {10}-5. A different class of objects temporally related to canonical CAIs are CAIs with fractionation and unidentified nuclear effects (FUN CAIs), which record a low initial <span class="hlt">26</span><span class="hlt">Al</span>/27Al of 10-6. The contrasting level of <span class="hlt">26</span><span class="hlt">Al</span> between these objects is often interpreted as reflecting the admixing of the <span class="hlt">26</span><span class="hlt">Al</span> nuclides during the early formative phase of the Sun. We use giant molecular cloud scale adaptive mesh-refinement numerical simulations to trace the abundance of <span class="hlt">26</span><span class="hlt">Al</span> and 60Fe in star-forming gas during the early stages of accretion of individual low-mass protostars. We find that the <span class="hlt">26</span><span class="hlt">Al</span>/27Al and 60Fe/56Fe ratios of accreting gas within a vicinity of 1000 au of the stars follow the predicted decay curves of the initial abundances at the time of star formation without evidence of spatial or temporal heterogeneities for the first 100 kyr of star formation. Therefore, the observed differences in <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratios between FUN and canonical CAIs are likely not caused by admixing of supernova material during the early evolution of the proto-Sun. Selective thermal processing of dust grains is a more viable scenario to account for the heterogeneity in <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratios at the time of solar system formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000APS..DNP.JB005C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000APS..DNP.JB005C"><span id="translatedtitle">Structure of ^27Na Using the ^<span class="hlt">14</span><span class="hlt">C</span>(^<span class="hlt">14</span><span class="hlt">C</span>,p) Reaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cooper, M. W.; Campbell, D. B.; Chandler, C.; Kemper, K. W.; Pipidis, A.; Riley, M. A.; Wiedeking, M.; Tabor, S. L.; Ragnarsson, I.</p> <p>2000-10-01</p> <p>Several new transitions in ^27Na were found using the ^<span class="hlt">14</span><span class="hlt">C</span>(^<span class="hlt">14</span><span class="hlt">C</span>,p) reaction at 22 MeV. The ^<span class="hlt">14</span><span class="hlt">C</span> target was 0.28 mg/cm^2 thick and the beam was stopped in a 33.8 mg/cm^2 Au foil. γ-γ, particle-γ, and particle-γ-γ coincidences were measured using 2 four-crystal Eurogam type ``clover'' detectors, 7 Compton suppressed HPGe detectors, and a particle E-ΔE telescope at 0^circ.The 67, 1660, 1752, 1820, and 2222 keV transitions, which are in coincidence with the high energy protons, have been identified as transitions in ^27Na. Some of the resulting levels correspond to particle groups seen in an earlier ^26Mg(^18O, ^17F) reaction (L.K. Fifield et al.), Nucl. Phys. A437, 141 (1985).. The results will be discussed in terms of both the shell model and the cranked Nilsson-Strutinsky rotational model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22130650','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22130650"><span id="translatedtitle">ABUNDANCE OF {sup <span class="hlt">26</span>}<span class="hlt">Al</span> AND {sup 60}Fe IN EVOLVING GIANT MOLECULAR CLOUDS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Vasileiadis, Aristodimos; Nordlund, Ake; Bizzarro, Martin</p> <p>2013-05-20</p> <p>The nucleosynthesis and ejection of radioactive {sup <span class="hlt">26</span>}<span class="hlt">Al</span> (t{sub 1/2} {approx} 0.72 Myr) and {sup 60}Fe, (t{sub 1/2} {approx} 2.5 Myr) into the interstellar medium is dominated by the stellar winds of massive stars and supernova type II explosions. Studies of meteorites and their components indicate that the initial abundances of these short-lived radionuclides in the solar protoplanetary disk were higher than the background levels of the galaxy inferred from {gamma}-ray astronomy and models of the galactic chemical evolution. This observation has been used to argue for a late-stage addition of stellar debris to the solar system's parental molecular cloud or, alternatively, the solar protoplanetary disk, thereby requiring a special scenario for the formation of our solar system. Here, we use supercomputers to model-from first principles-the production, transport, and admixing of freshly synthesized {sup <span class="hlt">26</span>}<span class="hlt">Al</span> and {sup 60}Fe in star-forming regions within giant molecular clouds. Under typical star formation conditions, the levels of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> in most star-forming regions are comparable to that deduced from meteorites, suggesting that the presence of short-lived radionuclides in the early solar system is a generic feature of the chemical evolution of giant molecular clouds. The {sup 60}Fe/{sup <span class="hlt">26</span>}<span class="hlt">Al</span> yield ratio of Almost-Equal-To 0.2 calculated from our simulations is consistent with the galactic value of 0.15 {+-} 0.06 inferred from {gamma}-ray astronomy but is significantly higher than most current solar system measurements indicate. We suggest that estimates based on differentiated meteorites and some chondritic components may not be representative of the initial {sup 60}Fe abundance of the bulk solar system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013NIMPB.294..692L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013NIMPB.294..692L"><span id="translatedtitle"><span class="hlt">14</span><span class="hlt">C</span> AMS dating Yongcheon cave</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, J. H.; Choe, K.; Kim, J. C.; Choi, S. H.; Kang, J.; Song, S.; Song, Y. M.; Jang, J. G.</p> <p>2013-01-01</p> <p>The biggest island in South Korea is Jeju Island, which lies 80 km south of the mainland and has one shield volcano, Mt. Halla. The volcanic island and its lava tubes were added to the world heritage list by UNESCO in 2007. Among the many lava tubes on the island, a unique cave had been accidentally found in 2005 while some workers were replacing a telephone pole. Until the discovery, it had been completely isolated from the outside by naturally-built sand blocks. Yongcheon cave is a lime-decorated lava tube showing both the properties of a volcanic lava tube and a limestone cave. This cave, about 3 km in length, is acknowledged to be the best of this type in the world and includes a large clean-water lake, lava falls, and richly developed speleothems inside it. Even though there is archaeological evidence from well preserved pottery that ancient people entered this place, the preservation of artifacts was ensured by a geological change that made later entrance difficult. We have collected charcoal samples scattered around the cave and dated them using AMS. Ages were in the range of ca. 1570-1260 BP (A.D. 340-880) and this corresponds to the Ancient Three Kingdoms and the Unified Silla era in Korean history. The <span class="hlt">14</span><span class="hlt">C</span> AMS measurement results presented in this paper on wood charcoal provide precise dates which will be very useful not only to clarify the nature of human activities in this cave but also to provide reference dates when comparing other dating methods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997NIMPB.123..259K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997NIMPB.123..259K"><span id="translatedtitle">Investigations of the human aluminium biokinetics with <span class="hlt">26</span><span class="hlt">Al</span> and AMS</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kislinger, G.; Steinhausen, C.; Alvarez-Brückmann, M.; Winklhofer, C.; Ittel, T.-H.; Nolte, E.</p> <p>1997-03-01</p> <p>Continuing the investigations on two healthy volunteers and on two patients with renal failure, the aluminium biokinetics in humans was studied by administering oral and intravenous doses of <span class="hlt">26</span><span class="hlt">Al</span> to three further healthy volunteers. Blood samples were drawn at times between 20 min and half a year after administration of the doses. The complete daily urine was collected during the first nine days, spot urine samples were taken at later times when blood samples were obtained. Creatinin renal clearances and haematocrit values were also obtained in the time period of the investigations. The <span class="hlt">26</span><span class="hlt">Al</span> concentrations of the samples were measured using the Munich Tandem accelerator. An open compartment model was developed to describe the time dependences of the measured <span class="hlt">26</span><span class="hlt">Al</span> concentrations in blood and urine and to establish the human Al biokinetics. The model comprises stomach and duodenum for oral administration, a central compartment consisting of blood plasma and interstitial fluid with transferrin and citrate binding and three peripheral compartments which are needed to describe the time dependence for the long observation period of up to three years. Excretion of Al was mainly described from plasma citrate via the kidneys into the urine and to a lesser extent from the plasma transferrin via the liver into the stool. Time constants between the compartments, fractional intestinal absorption factors and aluminium renal clearances were derived. It was found that the sizes of two peripheral compartments of the patients with renal failure were different to those of the healthy volunteers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15935683','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15935683"><span id="translatedtitle">Atmospheric <span class="hlt">14</span> <span class="hlt">C</span> CO 2 variations in Japan during 1982--1999 based on <span class="hlt">14</span> <span class="hlt">C</span> measurements of rice grains.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shibata, Setsuko; Kawano, Eiko; Nakabayashi, Takeshige</p> <p>2005-08-01</p> <p>(<span class="hlt">14</span>)<span class="hlt">C</span> in rice grains is a useful tracer of atmospheric (<span class="hlt">14</span>)<span class="hlt">C</span>(CO(2)). (<span class="hlt">14</span>)<span class="hlt">C</span> measurement in rice grains for 17 years during 1982--1999 reveals the following. There is negative correlation between Delta(<span class="hlt">14</span>)<span class="hlt">C</span> and the population densities of localities in Japan. Under-populated areas in the northern area of Japan and Okinawa remained clean in the 1990s. The (<span class="hlt">14</span>)<span class="hlt">C</span>(CO(2)) decline rates at those areas are near to that of Shauinsland. A latitudinal effect due to Chinese nuclear tests is observed in 1982. Small Seuss effects is observed at the middle latitudes in East Asia after 1995.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6970990','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6970990"><span id="translatedtitle">Uptake and distribution of /sup <span class="hlt">14</span>/<span class="hlt">C</span> during and following exposure to (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)methyl isocyanate</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ferguson, J.S.; Kennedy, A.L.; Stock, M.F.; Brown, W.E.; Alarie, Y.</p> <p>1988-06-15</p> <p>Guinea pigs were exposed to (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)methyl isocyanate (/sup 14/CH/sub 3/-NCO, /sup <span class="hlt">14</span>/<span class="hlt">C</span> MIC) for periods of 1 to 6 hr at concentrations of 0.5 to 15 ppm. Arterial blood samples taken during exposure revealed immediate and rapid uptake of /sup <span class="hlt">14</span>/<span class="hlt">C</span>. Clearance of /sup <span class="hlt">14</span>/<span class="hlt">C</span> was then gradual over a period of 3 days. Similarly /sup <span class="hlt">14</span>/<span class="hlt">C</span> was present in urine and bile immediately following exposure, and clearance paralleled that observed in blood. Guinea pigs fitted with a tracheal cannula and exposed while under anesthesia showed a reduced /sup <span class="hlt">14</span>/<span class="hlt">C</span> uptake in blood indicating that most of the /sup <span class="hlt">14</span>/<span class="hlt">C</span> MIC uptake in normal guinea pigs occurred from retention of this agent in the upper respiratory tract passages. In exposed guinea pigs /sup <span class="hlt">14</span>/<span class="hlt">C</span> was distributed to all examined tissues. In pregnant female mice similarly exposed to /sup <span class="hlt">14</span>/<span class="hlt">C</span> MIC, /sup <span class="hlt">14</span>/<span class="hlt">C</span> was observed in all tissues examined following exposure including the uterus, placenta, and fetus. While the form of /sup <span class="hlt">14</span>/<span class="hlt">C</span> distributed in blood and tissues has not yet been identified, these findings may help to explain the toxicity of MIC or MIC reaction products on organs other than the respiratory tract, as noted by several investigators.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_6 --> <div id="page_7" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="121"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1185230','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1185230"><span id="translatedtitle">The metabolism of [<span class="hlt">14</span><span class="hlt">C</span>]nicotine in the cat</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Turner, D. M.</p> <p>1969-01-01</p> <p>The metabolism of [2′-<span class="hlt">14</span><span class="hlt">C</span>]nicotine given as an intravenous injection in small doses to anaesthetized and unanaesthetized cats has been studied. A method is described for the quantitative determination of [<span class="hlt">14</span><span class="hlt">C</span>]nicotine and [<span class="hlt">14</span><span class="hlt">C</span>]cotinine in tissues and body fluids. Nanogram amounts of these compounds have been detected. After a single dose of 40μg. of [<span class="hlt">14</span><span class="hlt">C</span>]nicotine/kg., 55% of the injected radioactivity was excreted in the urine within 24hr., but only 1% of this radioactivity was unchanged nicotine. [<span class="hlt">14</span><span class="hlt">C</span>]Nicotine is metabolized extremely rapidly, [<span class="hlt">14</span><span class="hlt">C</span>]cotinine appearing in the blood within 2·5min. of intravenous injection. [<span class="hlt">14</span><span class="hlt">C</span>]Nicotine accumulates rapidly in the brain and 15min. after injection 90% of the radioactivity still represents [<span class="hlt">14</span><span class="hlt">C</span>]nicotine. Metabolites of [<span class="hlt">14</span><span class="hlt">C</span>]nicotine have been identified in liver and urine extracts. [<span class="hlt">14</span><span class="hlt">C</span>]Nicotine-1′-oxide has been detected in both liver and urine. PMID:5360723</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.176..295L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.176..295L"><span id="translatedtitle">Accretion timescales and style of asteroidal differentiation in an <span class="hlt">26</span><span class="hlt">Al</span>-poor protoplanetary disk</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Larsen, K. K.; Schiller, M.; Bizzarro, M.</p> <p>2016-03-01</p> <p>The decay of radioactive <span class="hlt">26</span><span class="hlt">Al</span> to 26Mg (half-life of 730,000 years) is postulated to have been the main energy source promoting asteroidal melting and differentiation in the nascent solar system. High-resolution chronological information provided by the <span class="hlt">26</span><span class="hlt">Al</span>-26Mg decay system is, therefore, intrinsically linked to the thermal evolution of early-formed planetesimals. In this paper, we explore the timing and style of asteroidal differentiation by combining high-precision Mg isotope measurements of meteorites with thermal evolution models for planetesimals. In detail, we report Mg isotope data for a suite of olivine-rich [Al/Mg ∼ 0] achondritic meteorites, as well as a few chondrites. Main Group, pyroxene and the Zinder pallasites as well as the lodranite all record deficits in the mass-independent component of μ26Mg (μ26Mg∗) relative to chondrites and Earth. This isotope signal is expected for the retarded ingrowth of radiogenic 26Mg∗ in olivine-rich residues produced through partial silicate melting during <span class="hlt">26</span><span class="hlt">Al</span> decay and consistent with their marginally heavy Mg isotope composition relative to ordinary chondrites, which may reflect the early extraction of isotopically light partial melts from the source rock. We propose that their parent planetesimals started forming within ∼250,000 years of solar system formation from a hot (>∼500 K) inner protoplanetary disk region characterized by a reduced initial (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 abundance (∼1-2 × 10-5) relative to the (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 value in CAIs of 5.25 × 10-5. This effectively reduced the total heat production and allowed for the preservation of solid residues produced through progressive silicate melting with depth within the planetesimals. These 'non-carbonaceous' planetesimals acquired their mass throughout an extended period (>3 Myr) of continuous accretion, thereby generating onion-shell structures of incompletely differentiated zones, consisting of olivine-rich residues, overlaid by metachondrites and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1816190M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1816190M"><span id="translatedtitle">The rock avalanche of the Mt. Peron (Eastern Alps, Italy): new insights from <span class="hlt">36</span><span class="hlt">Cl</span> exposure dating</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martin, Silvana; Ivy-ochs, Susan; Alfimov, Vasili; Vockenhuber, %Christof; Surian, Nicola; Campedel, Paolo; Rigo, Manuel; Viganò, Alfio; De Zorzi, Manuel</p> <p>2016-04-01</p> <p>In the Late Pleistocene, in the southern side of the Eastern Alps (Veneto region, Italy), when the glacier tongues retreated from the end moraine system areas towards the Dolomitic region, large rock avalanches took place. In the Belluno Valley, occupied by the Piave river, the left side is represented by the Belluno Prealps range, corresponding to the northern flank of a km-scale WSW-ENE oriented alpine syncline formed by rocks from Late Triassic to Late Tertiary in age. The Mt. Peron, belonging to this mountain range, shows its southern lower slope covered by debris cones with scattered boulders and its higher slope, corresponding to the scarp, made of vertical rock strata. At the foot of Mt. Peron, at a distance varying from 500 to 4500 m, there is a 4.5 km2 fan like area delimited by a perimeter of about 15 km. This is a hilly area of poortly sorted, chaotic deposits composed of heterogeneous debris, sandy and silty gravels, angular blocks and very large boulders of carbonatic rocks up to 20 m in diameter. The average thickness of the deposit was estimated to be 80 m, with maximum of 120 m. According to previous works, the main event occurred during the first phases of deglaciation, between 17,000 and 15,000 years BP. Popular stories narrate about two legendary villages destroyed by a mass of stones rolling down in the valley. This is confirmed by archeological findings in the Piave valley which indicate the presence of almost one pre-historic settlement dating 40000-20000 years a B.P., (i.e. before the Last Glacial Maximum).. Recent <span class="hlt">36</span><span class="hlt">Cl</span> exposure dating have yielded historical ages for both the boulders at the foot of the Mt Peron and those located a few km far from the main scarp. According to these exposure ages we can not exclude the hypothesis that earthquakes related to the Venetian faults could have played a key role for triggering of the rock avalanche and that the main gravitational event took place in historical times rather than during the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015GGG....16.2812V&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015GGG....16.2812V&link_type=ABSTRACT"><span id="translatedtitle">Late Pleistocene ages for the most recent volcanism and glacial-pluvial deposits at Big Pine volcanic field, California, USA, from cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> dating</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vazquez, J. A.; Woolford, J. M.</p> <p>2015-09-01</p> <p>The Big Pine volcanic field is one of several Quaternary volcanic fields that poses a potential volcanic hazard along the tectonically active Owens Valley of east-central California, and whose lavas are interbedded with deposits from Pleistocene glaciations in the Sierra Nevada Range. Previous geochronology indicates an ˜1.2 Ma history of volcanism, but the eruption ages and distribution of volcanic products associated with the most-recent eruptions have been poorly resolved. To delimit the timing and products of the youngest volcanism, we combine field mapping and cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> dating of basaltic lava flows in the area where lavas with youthful morphology and well-preserved flow structures are concentrated. Field mapping and petrology reveal approximately 15 vents and 6 principal flow units with variable geochemical composition and mineralogy. Cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> exposure ages for lava flow units from the top, middle, and bottom of the volcanic stratigraphy indicate eruptions at ˜17, 27, and 40 ka, revealing several different and previously unrecognized episodes of late Pleistocene volcanism. Olivine to plagioclase-pyroxene phyric basalt erupted from several vents during the most recent episode of volcanism at ˜17 ka, and produced a lava flow field covering ˜35 km2. The late Pleistocene <span class="hlt">36</span><span class="hlt">Cl</span> exposure ages indicate that moraine and pluvial shoreline deposits that overlie or modify the youngest Big Pine lavas reflect Tioga stage glaciation in the Sierra Nevada and the shore of paleo-Owens Lake during the last glacial cycle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70157344','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70157344"><span id="translatedtitle">Late Pleistocene ages for the most recent volcanism and glacial-pluvial deposits at Big Pine volcanic field, California, USA, from cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> dating</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Vazquez, Jorge A.; Woolford, Jeff M</p> <p>2015-01-01</p> <p>The Big Pine volcanic field is one of several Quaternary volcanic fields that poses a potential volcanic hazard along the tectonically active Owens Valley of east-central California, and whose lavas are interbedded with deposits from Pleistocene glaciations in the Sierra Nevada Range. Previous geochronology indicates an ∼1.2 Ma history of volcanism, but the eruption ages and distribution of volcanic products associated with the most-recent eruptions have been poorly resolved. To delimit the timing and products of the youngest volcanism, we combine field mapping and cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> dating of basaltic lava flows in the area where lavas with youthful morphology and well-preserved flow structures are concentrated. Field mapping and petrology reveal approximately 15 vents and 6 principal flow units with variable geochemical composition and mineralogy. Cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> exposure ages for lava flow units from the top, middle, and bottom of the volcanic stratigraphy indicate eruptions at ∼17, 27, and 40 ka, revealing several different and previously unrecognized episodes of late Pleistocene volcanism. Olivine to plagioclase-pyroxene phyric basalt erupted from several vents during the most recent episode of volcanism at ∼17 ka, and produced a lava flow field covering ∼35 km2. The late Pleistocene <span class="hlt">36</span><span class="hlt">Cl</span> exposure ages indicate that moraine and pluvial shoreline deposits that overlie or modify the youngest Big Pine lavas reflect Tioga stage glaciation in the Sierra Nevada and the shore of paleo-Owens Lake during the last glacial cycle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.3563Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.3563Z"><span id="translatedtitle">Dating chert using in-situ produced 10Be: Possible complications revealed on landslide scarps through a comparison with <span class="hlt">36</span><span class="hlt">Cl</span> applied to coexisting limestone.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zerathe, Swann; Braucher, Régis; Lebourg, Thomas; Leani, Leatitia; Manetti, Michel; Bourles, Didier</p> <p>2013-04-01</p> <p>This abstract and presentation highlights potential complications that may arise while using in situ produced 10Be to date diagenetic silica (chert)exposure or burial event. The initiation and evolution of large gravitational collapses in sedimentary rocks were constrained using cosmic ray exposure dating. Because these collapses occurred in a stratigraphic level composed of chert (diagenetic silica) concretions interbedded in limestone layers, their development was studied by performing in situ-produced <span class="hlt">36</span><span class="hlt">Cl</span> and 10Be concentration measurements in both the limestone and coexisting diagenetic silica (chert), respectively. Following the routinely used decontamination and preparation protocols for 10Be produced in diagenetic silica, large discrepancies were observed with exposure ages determined by <span class="hlt">36</span><span class="hlt">Cl</span> within carbonate for samples originating from the same scarp. While <span class="hlt">36</span><span class="hlt">Cl</span> exposure ages were clustered as expected for a unique single gravitational event, 10Be exposure ages were scattered along the same studied scarps. To determine the origin of such a bias, petrological investigations were carried out for chert (diagenetic silica). Thin sections highlighted a complex mineralogical texture characterized by remnant silicified ooids showing calcitic cores, calcite inclusions and a dominant amorphous hydrated silica (grain > 20 μm). To decipher and characterize the potential origins of the excess measured 10Be within diagenetic silica, all samples were first reprocessed following the routine decontamination protocol (HCL-H2SiF6 leachings and three partial HF dissolutions) but starting from three different grain size fractions (GS1: 1000-500, GS2: 500-250 and GS3: 250-50 μm). The resulting concentrations clearly showed a decreasing 10Be content as a function of the grain size, but still yielded 10Be exposure ages significantly higher than <span class="hlt">36</span><span class="hlt">Cl</span> counterparts. Because potential adsorption of 10Be at the surface of amorphous silica grains was suspected, partial dissolution</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4950964','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4950964"><span id="translatedtitle">Accretion timescales and style of asteroidal differentiation in an <span class="hlt">26</span><span class="hlt">Al</span>-poor protoplanetary disk</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Larsen, K.K.; Schiller, M.; Bizzarro, M.</p> <p>2016-01-01</p> <p>The decay of radioactive <span class="hlt">26</span><span class="hlt">Al</span> to 26Mg (half-life of 730,000 years) is postulated to have been the main energy source promoting asteroidal melting and differentiation in the nascent solar system. High-resolution chronological information provided by the 26Al−26Mg decay system is, therefore, intrinsically linked to the thermal evolution of early-formed planetesimals. In this paper, we explore the timing and style of asteroidal differentiation by combining high-precision Mg isotope measurements of meteorites with thermal evolution models for planetesimals. In detail, we report Mg isotope data for a suite of olivine-rich [Al/Mg ~ 0] achondritic meteorites, as well as a few chondrites. Main Group, pyroxene and the Zinder pallasites as well as the lodranite all record deficits in the mass-independent component of μ26Mg (μ26Mg*) relative to chondrites and Earth. This isotope signal is expected for the retarded ingrowth of radiogenic 26Mg* in olivine-rich residues produced through partial silicate melting during <span class="hlt">26</span><span class="hlt">Al</span> decay and consistent with their marginally heavy Mg isotope composition relative to ordinary chondrites, which may reflect the early extraction of isotopically light partial melts from the source rock. We propose that their parent planetesimals started forming within ~250,000 years of solar system formation from a hot (>~500 K) inner protoplanetary disk region characterized by a reduced initial (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 abundance (~1–2 × 10−5) relative to the (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 value in CAIs of 5.25 × 10−5. This effectively reduced the total heat production and allowed for the preservation of solid residues produced through progressive silicate melting with depth within the planetesimals. These ‘non-carbonaceous’ planetesimals acquired their mass throughout an extended period (>3 Myr) of continuous accretion, thereby generating onion-shell structures of incompletely differentiated zones, consisting of olivine-rich residues, overlaid by metachondrites and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/19962904','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/19962904"><span id="translatedtitle">Root-uptake of (<span class="hlt">14</span>)<span class="hlt">C</span> derived from acetic acid and (<span class="hlt">14</span>)<span class="hlt">C</span> transfer to rice edible parts.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ogiyama, Shinichi; Suzuki, Hiroyuki; Inubushi, Kazuyuki; Takeda, Hiroshi; Uchida, Shigeo</p> <p>2010-02-01</p> <p>Three types of culture experiments using paddy rice (Oryza sativa L.) were performed to examine root-uptake of (<span class="hlt">14</span>)<span class="hlt">C</span> in the form of acetic acid: double pot experiment (hydroponics), wet culture experiment (submerged sand medium), and chamber experiment (hydroponics and submerged sand medium). The (<span class="hlt">14</span>)<span class="hlt">C</span> radioactivity in the plant, mediums, and atmospheric carbon dioxide ((14)CO(2)) in the chamber were determined, and the distribution of (<span class="hlt">14</span>)<span class="hlt">C</span> in the plant was visualized using autoradiography. In the double pot experiment, the shoot of the plant and the lower root which was soaked in the culture solution had (<span class="hlt">14</span>)<span class="hlt">C</span> radioactivity, but the upper root which did not have contact with the solution had none. There were also (<span class="hlt">14</span>)<span class="hlt">C</span> radioactivity in the grains and roots in the wet culture experiment. Results of the chamber experiment showed that (14)CO(2) gas was released from the culture solution in both types of cultures. Results indicated that the (<span class="hlt">14</span>)<span class="hlt">C</span>-acetic acid absorbed by rice plant through its root would be very small. Most of the (<span class="hlt">14</span>)<span class="hlt">C</span>-acetic acid was transformed into gaseous forms either in the culture solution or rhizosphere. A relatively longer time would be needed to assimilate (<span class="hlt">14</span>)<span class="hlt">C</span> derived from acetic acid to grain parts after it was once absorbed by the shoot through the root. Availability of (<span class="hlt">14</span>)<span class="hlt">C</span> for the plant in sand culture was considered to be decreased compared with that for the plant in the hydroponics experiment. It was suggested that rice plant absorbed and assimilated (<span class="hlt">14</span>)<span class="hlt">C</span> through the plant roots not because of uptake of (<span class="hlt">14</span>)<span class="hlt">C</span>-acetic acid but because of uptake of (<span class="hlt">14</span>)<span class="hlt">C</span> in gaseous forms such as (14)CO(2). PMID:19962904</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title17-vol3/pdf/CFR-2010-title17-vol3-sec240-14c-1.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title17-vol3/pdf/CFR-2010-title17-vol3-sec240-14c-1.pdf"><span id="translatedtitle">17 CFR 240.<span class="hlt">14</span><span class="hlt">c</span>-1 - Definitions.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-04-01</p> <p>... to indicate a relationship with any person, means: (1) Any corporation or organization (other than..., addresses and securities positions of beneficial owners has been given pursuant to § 240.<span class="hlt">14</span><span class="hlt">c</span>-7(b)(3... purposes of § 240.<span class="hlt">14</span><span class="hlt">c</span>-7, the term “record holder” means any broker, dealer, voting trustee,...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/2258015','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/2258015"><span id="translatedtitle">Percutaneous absorption of [<span class="hlt">14</span><span class="hlt">C</span>]DDT and [<span class="hlt">14</span><span class="hlt">C</span>]benzo[a]pyrene from soil.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wester, R C; Maibach, H I; Bucks, D A; Sedik, L; Melendres, J; Liao, C; DiZio, S</p> <p>1990-10-01</p> <p>The objective was to determine percutaneous absorption of DDT and benzo[a]pyrene in vitro and in vivo from soil into and through skin. Soil (Yolo County 65-California-57-8; 26% sand, 26% clay, 48% silt) was passed through 10-, 20-, and 48-mesh sieves. Soil then retained by 80-mesh was mixed with [<span class="hlt">14</span><span class="hlt">C</span>]-labeled chemical at 10 ppm. Acetone solutions at 10 ppm were prepared for comparative analysis. Human cadaver skin was dermatomed to 500 microns and used in glass diffusion cells with human plasma as the receptor fluid (3 ml/hr flow rate) for a 24-hr skin application time. With acetone vehicle, DDT (18.1 +/- 13.4%) readily penetrated into human skin. Significantly less DDT (1.0 +/- 0.7%) penetrated into human skin from soil. DDT would not partition from human skin into human plasma in the receptor phase (less than 0.1%). With acetone vehicle, benzo[a]pyrene (23.7 +/- 9.7%) readily penetrated into human skin. Significantly less benzo[a]pyrene (1.4 +/- 0.9%) penetrated into human skin from soil. Benzo[a]pyrene would not partition from human skin into human plasma in the receptor phase (less than 0.1%). Substantivity (skin retention) was investigated by applying <span class="hlt">14</span><span class="hlt">C</span>-labeled chemical to human skin in vitro for only 25 min. After soap and water wash, 16.7 +/- 13.2% of DDT applied in acetone remained absorbed to skin. With soil only 0.25 +/- 0.11% of DDT remained absorbed to skin. After soap and water wash 5.1 +/- 2.1% of benzo[a]pyrene applied in acetone remained absorbed to skin. With soil only 0.14 +/- 0.13% of benzo[a]pyrene remained absorbed to skin.(ABSTRACT TRUNCATED AT 250 WORDS)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7243329','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7243329"><span id="translatedtitle">Decay of sup 226 Ra by sup <span class="hlt">14</span> <span class="hlt">C</span> emission</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Weselka, D.; Hille, P.; Chalupka, A. )</p> <p>1990-02-01</p> <p>Previous observation of heavy-ion emission from {sup 226}Ra has been confirmed. Charge and energy of the emitted fragment were measured using thin {sup 226}Ra sources and polycarbonate track-recording films. Decay by {sup <span class="hlt">14</span>}<span class="hlt">C</span> emission could be identified unambiguously. The track-detector was calibrated with tandem-accelerated {sup <span class="hlt">14</span>}<span class="hlt">C</span> and {sup 16}O ions and tested by observing the {sup <span class="hlt">14</span>}<span class="hlt">C</span> emission from {sup 223}Ra yielding a branching ratio of (5.0{plus minus}1.0){times}10{sup {minus}10}. In the case of {sup 226}Ra our result for the {sup <span class="hlt">14</span>}<span class="hlt">C</span>/{alpha} ratio is (2.3{plus minus}0.8){times}10{sup {minus}11}. Estimates of partial half-lives of Ra isotopes for {sup <span class="hlt">14</span>}<span class="hlt">C</span> emission are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFM.P32A..01C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.P32A..01C"><span id="translatedtitle"><span class="hlt">26</span><span class="hlt">Al</span> in the Saturnian System - New Interior Models for the Saturnian satellites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Castillo, J. C.; Matson, D. L.; Johnson, T. V.; Lunine, J. I.; McCord, T. B.; Sotin, C.; Thomas, P. C.; Turtle, E. B.</p> <p>2005-12-01</p> <p>Recent study of Iapetus' spin rate evolution highlights the need to form this satellite between between 1.0+/- 0.2 to 1.6+/- 0.4 My after the production of Calcium-Aluminum Inclusions (CAIs). We study the implications of this time constraint on the thermal evolution of other "icy" Saturnian satellites, assuming that they formed at the same time as Iapetus and from the same rocky material in proportion to their densities. Heat provided by <span class="hlt">26</span><span class="hlt">Al</span> decay contributes to partial to full melting and thus differentiation of all Saturn's medium-sized satellites, except Tethys. We also consider the effect of silicate hydration on the internal and geological evolution of these satellites. These results are compared with classical models (that do not include short-lived radiogenic species), in the light of the observational constraints available for these satellites. Including <span class="hlt">26</span><span class="hlt">Al</span> decay in the heat budget of the satellites allows to explain the observation of geological activity in silicate-poor satellites such as Tethys. We note that in Enceladus and Titan conditions might have been such that the boiling point of water was reached and water might have been lost very early in the history of these satellites. This opens the door to some explanation for the variations in density within the Saturnian system. Part of this work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25459713','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25459713"><span id="translatedtitle">Vibrations and reorientations of NH3 molecules in [Mn(NH3)6](ClO4)2 studied by infrared spectroscopy and theoretical (DFT) calculations.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hetmańczyk, Joanna; Hetmańczyk, Łukasz; Migdał-Mikuli, Anna; Mikuli, Edward</p> <p>2015-02-01</p> <p>The vibrational and reorientational motions of NH3 ligands and ClO4(-) anions were investigated by Fourier transform middle-infrared spectroscopy (FT-IR) in the high- and low-temperature phases of [Mn(NH3)6](ClO4)2. The temperature dependencies of full width at half maximum (FWHM) of the infrared bands at: 591 and 3385cm(-1), associated with: ρr(NH3) and νas(N-H) modes, respectively, indicate that there exist fast (correlation times τR≈10(-12)-10(-13)s) reorientational motions of NH3 ligands, with a mean values of activation energies: 7.8 and 4.5kJmol(-1), in the phase I and II, respectively. These reorientational motions of NH3 ligands are only slightly disturbed in the phase transition region and do not significantly contribute to the phase transition mechanism. Fourier transform far-infrared and middle-infrared spectra with decreasing of temperature indicated characteristic changes at the vicinity of PT at TC(c)=137.6K (on cooling), which suggested lowering of the crystal structure symmetry. Infrared spectra of [Mn(NH3)6](ClO4)2 were recorded and interpreted by comparison with respective theoretical spectra calculated using DFT method (B3LYP functional, LANL2DZ ECP basis set (on Mn atom) and 6-311+G(d,p) basis set (on H, N, Cl, O atoms) for the isolated equilibrium two models (Model 1 - separate isolated [Mn(NH3)6](2+) cation and ClO4(-) anion and Model 2 - [Mn(NH3)6(ClO4)2] complex system). Calculated optical spectra show a good agreement with the experimental infrared spectra (FT-FIR and FT-MIR) for the both models. PMID:25459713</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18389270','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18389270"><span id="translatedtitle">Intercomparison study on (152)Eu gamma ray and (<span class="hlt">36</span>)<span class="hlt">Cl</span> AMS measurements for development of the new Hiroshima-Nagasaki Atomic Bomb Dosimetry System 2002 (DS02).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hoshi, M; Endo, S; Tanaka, K; Ishikawa, M; Straume, T; Komura, K; Rühm, W; Nolte, E; Huber, T; Nagashima, Y; Seki, R; Sasa, K; Sueki, K; Fukushima, H; Egbert, S D; Imanaka, T</p> <p>2008-07-01</p> <p>In the process of developing a new dosimetry system for atomic bomb survivors in Hiroshima and Nagasaki (DS02), an intercomparison study between (152)Eu and (<span class="hlt">36</span>)<span class="hlt">Cl</span> measurements was proposed, to reconcile the discrepancy previously observed in the Hiroshima data between measurements and calculations of thermal neutron activation products. Nine granite samples, exposed to the atomic-bomb radiation in Hiroshima within 1,200 m of the hypocenter, as well as mixed standard solutions containing known amounts of europium and chlorine that were neutron-activated by a (252)Cf source, were used for the intercomparison. Gamma-ray spectrometry for (152)Eu was carried out with ultra low-background Ge detectors at the Ogoya Underground Laboratory, Kanazawa University, while three laboratories participated in the (<span class="hlt">36</span>)<span class="hlt">Cl</span> measurement using accelerator mass spectrometry (AMS): The Technical University of Munich, Germany, the Lawrence Livermore National Laboratory, USA and the University of Tsukuba, Japan. Measured values for the mixed standard solutions showed good agreement among the participant laboratories. They also agreed well with activation calculations, using the neutron fluences monitored during the (252)Cf irradiation, and the corresponding activation cross-sections taken from the JENDL-3.3 library. The measured-to-calculated ratios obtained were 1.02 for (152)Eu and 0.91-1.02 for (<span class="hlt">36</span>)<span class="hlt">Cl</span>, respectively. Similarly, the results of the granite intercomparison indicated good agreement with the DS02 calculation for these samples. An average measured-to-calculated ratio of 0.98 was obtained for all granite intercomparison measurements. The so-called neutron discrepancy that was previously observed and that which included increasing measured-to-calculated ratios for thermal neutron activation products for increasing distances beyond 1,000 m from the hypocenter was not seen in the results of the intercomparison study. The previously claimed discrepancy could be explained by</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AcSpA.136.1515H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AcSpA.136.1515H"><span id="translatedtitle">Vibrations and reorientations of NH3 molecules in [Mn(NH3)6](ClO4)2 studied by infrared spectroscopy and theoretical (DFT) calculations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hetmańczyk, Joanna; Hetmańczyk, Łukasz; Migdał-Mikuli, Anna; Mikuli, Edward</p> <p>2015-02-01</p> <p>The vibrational and reorientational motions of NH3 ligands and ClO4- anions were investigated by Fourier transform middle-infrared spectroscopy (FT-IR) in the high- and low-temperature phases of [Mn(NH3)6](ClO4)2. The temperature dependencies of full width at half maximum (FWHM) of the infrared bands at: 591 and 3385 cm-1, associated with: ρr(NH3) and νas(N-H) modes, respectively, indicate that there exist fast (correlation times τR ≈ 10-12-10-13 s) reorientational motions of NH3 ligands, with a mean values of activation energies: 7.8 and 4.5 kJ mol-1, in the phase I and II, respectively. These reorientational motions of NH3 ligands are only slightly disturbed in the phase transition region and do not significantly contribute to the phase transition mechanism. Fourier transform far-infrared and middle-infrared spectra with decreasing of temperature indicated characteristic changes at the vicinity of PT at TCc = 137.6 K (on cooling), which suggested lowering of the crystal structure symmetry. Infrared spectra of [Mn(NH3)6](ClO4)2 were recorded and interpreted by comparison with respective theoretical spectra calculated using DFT method (B3LYP functional, LANL2DZ ECP basis set (on Mn atom) and 6-311 + G(d,p) basis set (on H, N, Cl, O atoms) for the isolated equilibrium two models (Model 1 - separate isolated [Mn(NH3)6]2+ cation and ClO4- anion and Model 2 - [Mn(NH3)6(ClO4)2] complex system). Calculated optical spectra show a good agreement with the experimental infrared spectra (FT-FIR and FT-MIR) for the both models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/2882009','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/2882009"><span id="translatedtitle">The in-vitro metabolism of [<span class="hlt">14</span><span class="hlt">C</span>]pentobarbitone and [<span class="hlt">14</span><span class="hlt">C</span>]phenobarbitone by hamster liver microsomes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Seago, A; Gorrod, J W</p> <p>1987-02-01</p> <p>The metabolism of [<span class="hlt">14</span><span class="hlt">C</span>]pentobarbitone and [<span class="hlt">14</span><span class="hlt">C</span>]phenobarbitone has been reinvestigated using an in-vitro hepatic microsomal system (Syrian hamsters, Aroclor 1254 induction). The incubation system was routinely supplemented with EDTA (1 mM) and a substrate concentration study revealed the metabolism of [<span class="hlt">14</span><span class="hlt">C</span>]pentobarbitone to be concentration-dependent, with the greatest overall metabolism (greater than 50%) occurring at 0.054 mumol per 3.5 mL. With [<span class="hlt">14</span><span class="hlt">C</span>]phenobarbitone as substrate, overall metabolism was extremely low (3%) and independent of substrate concentration. Addition of further cofactors to the incubation mixture at 20 min intervals over an extended period resulted in almost complete metabolism of [<span class="hlt">14</span><span class="hlt">C</span>]pentobarbitone (100 min), 3'-hydroxypentobarbitone and 3'-oxopentobarbitone being identified as metabolites together with many minor, unidentified products. With [<span class="hlt">14</span><span class="hlt">C</span>]phenobarbitone as the substrate, cofactor addition up to 120 min resulted in 8% overall metabolism; p-hydroxyphenobarbitone was identified as a product of metabolism; other minor products were unidentified. The metabolism studies failed to produce a metabolite having the properties of the N-hydroxylated product of either [<span class="hlt">14</span><span class="hlt">C</span>]pentobarbitone or [<span class="hlt">14</span><span class="hlt">C</span>]phenobarbitone within the detection limits available (0.02% of 0.5 mumol per incubate).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GMD.....8.2079K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GMD.....8.2079K"><span id="translatedtitle"><span class="hlt">14</span><span class="hlt">C</span>-age tracers in global ocean circulation models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koeve, W.; Wagner, H.; Kähler, P.; Oschlies, A.</p> <p>2015-07-01</p> <p>The natural abundance of <span class="hlt">14</span><span class="hlt">C</span> in total CO2 dissolved in seawater (DIC) is a property applied to evaluate the water age structure and circulation in the ocean and in ocean models. In this study we use three different representations of the global ocean circulation augmented with a suite of idealised tracers to study the potential and limitations of using natural <span class="hlt">14</span><span class="hlt">C</span> to determine water age, which is the time elapsed since a body of water has been in contact with the atmosphere. We find that, globally, bulk <span class="hlt">14</span><span class="hlt">C</span>-age is dominated by two equally important components, one associated with ageing, i.e. the time component of circulation, and one associated with a "preformed <span class="hlt">14</span><span class="hlt">C</span>-age". The latter quantity exists because of the slow and incomplete atmosphere-ocean equilibration of <span class="hlt">14</span><span class="hlt">C</span> particularly in high latitudes where many water masses form. In the ocean's interior, preformed <span class="hlt">14</span><span class="hlt">C</span>-age behaves like a passive tracer. The relative contribution of the preformed component to bulk <span class="hlt">14</span><span class="hlt">C</span>-age varies regionally within a given model, but also between models. Regional variability in the Atlantic Ocean is associated with the mixing of waters with very different end members of preformed <span class="hlt">14</span><span class="hlt">C</span>-age. Here, variations in the preformed component over space and time mask the circulation component to an extent that its patterns are not detectable from bulk <span class="hlt">14</span><span class="hlt">C</span>-age. Between models, the variability of preformed <span class="hlt">14</span><span class="hlt">C</span>-age can also be considerable (factor of 2), related to the combination of physical model parameters, which influence circulation dynamics or gas exchange. The preformed component was found to be very sensitive to gas exchange and moderately sensitive to ice cover. In our model evaluation, the choice of the gas-exchange constant from within the currently accepted range of uncertainty had such a strong influence on preformed and bulk <span class="hlt">14</span><span class="hlt">C</span>-age that if model evaluation would be based on bulk <span class="hlt">14</span><span class="hlt">C</span>-age, it could easily impair the evaluation and tuning of a model's circulation on global and regional</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011AGUFMPP43A1799M&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011AGUFMPP43A1799M&link_type=ABSTRACT"><span id="translatedtitle">A Coral Based Reconstruction of Atmospheric Δ<span class="hlt">14</span><span class="hlt">C</span> through the Mystery Interval (17.5 to 14.5 kyr BP)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mortlock, R. A.; Abdul, N. A.; Wright, J. D.; Fairbanks, R. G.; Cao, L.</p> <p>2011-12-01</p> <p> duration of the Mystery Interval. Thus, a ~130% decrease in atmospheric Δ<span class="hlt">14</span><span class="hlt">C</span> recorded by corals precedes the Mystery Interval and atmospheric CO2 rise. We observe a second, more abrupt (less than 800 years) ~100% decrease in Δ<span class="hlt">14</span><span class="hlt">C</span> prior to the Bølling-Allerød period which appears as a plateau in the radiocarbon vs. calendar age relationship. An increase in atmospheric Δ<span class="hlt">14</span><span class="hlt">C</span> between 20 and 18.5 kyr BP could be explained by increased production as a result of a weakening of the earth's magnetic field or from reduced deep-water formation. Paleointensity records from North Atlantic deep-sea cores suggest weakening in the magnetic field at about 20 kyr BP and magnetic data from Lake Bailkal, Biwa, and Hawaiian lavas also support a short term magnetic excursion centered at about 20 ka BP. The accumulation of cosmogenic nuclides (<span class="hlt">36</span><span class="hlt">Cl</span>, 10Be) in Greenland ice, however, does not provide compelling evidence for significantly reduced field strength at this time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25157825','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25157825"><span id="translatedtitle">TMEM<span class="hlt">14</span><span class="hlt">C</span> is required for erythroid mitochondrial heme metabolism.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yien, Yvette Y; Robledo, Raymond F; Schultz, Iman J; Takahashi-Makise, Naoko; Gwynn, Babette; Bauer, Daniel E; Dass, Abhishek; Yi, Gloria; Li, Liangtao; Hildick-Smith, Gordon J; Cooney, Jeffrey D; Pierce, Eric L; Mohler, Kyla; Dailey, Tamara A; Miyata, Non; Kingsley, Paul D; Garone, Caterina; Hattangadi, Shilpa M; Huang, Hui; Chen, Wen; Keenan, Ellen M; Shah, Dhvanit I; Schlaeger, Thorsten M; DiMauro, Salvatore; Orkin, Stuart H; Cantor, Alan B; Palis, James; Koehler, Carla M; Lodish, Harvey F; Kaplan, Jerry; Ward, Diane M; Dailey, Harry A; Phillips, John D; Peters, Luanne L; Paw, Barry H</p> <p>2014-10-01</p> <p>The transport and intracellular trafficking of heme biosynthesis intermediates are crucial for hemoglobin production, which is a critical process in developing red cells. Here, we profiled gene expression in terminally differentiating murine fetal liver-derived erythroid cells to identify regulators of heme metabolism. We determined that TMEM<span class="hlt">14</span><span class="hlt">C</span>, an inner mitochondrial membrane protein that is enriched in vertebrate hematopoietic tissues, is essential for erythropoiesis and heme synthesis in vivo and in cultured erythroid cells. In mice, TMEM<span class="hlt">14</span><span class="hlt">C</span> deficiency resulted in porphyrin accumulation in the fetal liver, erythroid maturation arrest, and embryonic lethality due to profound anemia. Protoporphyrin IX synthesis in TMEM<span class="hlt">14</span><span class="hlt">C</span>-deficient erythroid cells was blocked, leading to an accumulation of porphyrin precursors. The heme synthesis defect in TMEM<span class="hlt">14</span><span class="hlt">C</span>-deficient cells was ameliorated with a protoporphyrin IX analog, indicating that TMEM<span class="hlt">14</span><span class="hlt">C</span> primarily functions in the terminal steps of the heme synthesis pathway. Together, our data demonstrate that TMEM<span class="hlt">14</span><span class="hlt">C</span> facilitates the import of protoporphyrinogen IX into the mitochondrial matrix for heme synthesis and subsequent hemoglobin production. Furthermore, the identification of TMEM<span class="hlt">14</span><span class="hlt">C</span> as a protoporphyrinogen IX importer provides a genetic tool for further exploring erythropoiesis and congenital anemias.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4191016','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4191016"><span id="translatedtitle">TMEM<span class="hlt">14</span><span class="hlt">C</span> is required for erythroid mitochondrial heme metabolism</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Yien, Yvette Y.; Robledo, Raymond F.; Schultz, Iman J.; Takahashi-Makise, Naoko; Gwynn, Babette; Bauer, Daniel E.; Dass, Abhishek; Yi, Gloria; Li, Liangtao; Hildick-Smith, Gordon J.; Cooney, Jeffrey D.; Pierce, Eric L.; Mohler, Kyla; Dailey, Tamara A.; Miyata, Non; Kingsley, Paul D.; Garone, Caterina; Hattangadi, Shilpa M.; Huang, Hui; Chen, Wen; Keenan, Ellen M.; Shah, Dhvanit I.; Schlaeger, Thorsten M.; DiMauro, Salvatore; Orkin, Stuart H.; Cantor, Alan B.; Palis, James; Koehler, Carla M.; Lodish, Harvey F.; Kaplan, Jerry; Ward, Diane M.; Dailey, Harry A.; Phillips, John D.; Peters, Luanne L.; Paw, Barry H.</p> <p>2014-01-01</p> <p>The transport and intracellular trafficking of heme biosynthesis intermediates are crucial for hemoglobin production, which is a critical process in developing red cells. Here, we profiled gene expression in terminally differentiating murine fetal liver-derived erythroid cells to identify regulators of heme metabolism. We determined that TMEM<span class="hlt">14</span><span class="hlt">C</span>, an inner mitochondrial membrane protein that is enriched in vertebrate hematopoietic tissues, is essential for erythropoiesis and heme synthesis in vivo and in cultured erythroid cells. In mice, TMEM<span class="hlt">14</span><span class="hlt">C</span> deficiency resulted in porphyrin accumulation in the fetal liver, erythroid maturation arrest, and embryonic lethality due to profound anemia. Protoporphyrin IX synthesis in TMEM<span class="hlt">14</span><span class="hlt">C</span>-deficient erythroid cells was blocked, leading to an accumulation of porphyrin precursors. The heme synthesis defect in TMEM<span class="hlt">14</span><span class="hlt">C</span>-deficient cells was ameliorated with a protoporphyrin IX analog, indicating that TMEM<span class="hlt">14</span><span class="hlt">C</span> primarily functions in the terminal steps of the heme synthesis pathway. Together, our data demonstrate that TMEM<span class="hlt">14</span><span class="hlt">C</span> facilitates the import of protoporphyrinogen IX into the mitochondrial matrix for heme synthesis and subsequent hemoglobin production. Furthermore, the identification of TMEM<span class="hlt">14</span><span class="hlt">C</span> as a protoporphyrinogen IX importer provides a genetic tool for further exploring erythropoiesis and congenital anemias. PMID:25157825</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_7 --> <div id="page_8" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="141"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24814329','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24814329"><span id="translatedtitle"><span class="hlt">14</span><span class="hlt">C</span> Analysis of protein extracts from Bacillus spores.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cappuccio, Jenny A; Falso, Miranda J Sarachine; Kashgarian, Michaele; Buchholz, Bruce A</p> <p>2014-07-01</p> <p>Investigators of bioagent incidents or interdicted materials need validated, independent analytical methods that will allow them to distinguish between recently made bioagent samples versus material drawn from the archives of a historical program. Heterotrophic bacteria convert the carbon in their food sources, growth substrate or culture media, into the biomolecules they need. The F(<span class="hlt">14</span>)<span class="hlt">C</span> (fraction modern radiocarbon) of a variety of media, Bacillus spores, and separated proteins from Bacillus spores was measured by accelerator mass spectrometry (AMS). AMS precisely measures F(<span class="hlt">14</span>)<span class="hlt">C</span> values of biological materials and has been used to date the synthesis of biomaterials over the bomb pulse era (1955 to present). The F(<span class="hlt">14</span>)<span class="hlt">C</span> of Bacillus spores reflects the radiocarbon content of the media in which they were grown. In a survey of commercial media we found that the F(<span class="hlt">14</span>)<span class="hlt">C</span> value indicated that carbon sources for the media were alive within about a year of the date of manufacture and generally of terrestrial origin. Hence, bacteria and their products can be dated using their (<span class="hlt">14</span>)<span class="hlt">C</span> signature. Bacillus spore samples were generated onsite with defined media and carbon free purification and also obtained from archived material. Using mechanical lysis and a variety of washes with carbon free acids and bases, contaminant carbon was removed from soluble proteins to enable accurate (<span class="hlt">14</span>)<span class="hlt">C</span> bomb-pulse dating. Since media is contemporary, (<span class="hlt">14</span>)<span class="hlt">C</span> bomb-pulse dating of isolated soluble proteins can be used to distinguish between historical archives of bioagents and those produced from recent media.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/15204532','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/15204532"><span id="translatedtitle">Determination of <span class="hlt">14</span><span class="hlt">C</span> residue in eggs of laying hens administered orally with [<span class="hlt">14</span><span class="hlt">C</span>] sulfaquinoxaline.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shaikh, B; Rummel, N; Smith, D</p> <p>2004-06-01</p> <p>Ten layer hens were dosed for 5 consecutive days with 6.2 mg kg(-1) [<span class="hlt">14</span><span class="hlt">C</span>] sulfaquinoxaline (SQX). Eggs were collected from the hens during the 5-day dosing period and during a 10-day post-dose withdrawal period. Egg yolk and albumen were separated and assayed for total radioactive residues (TRR) using a combustion oxidizer and liquid scintillation counting techniques. Significant amounts of radioactivity were detected on the second day of dosing (greater than 24h after the initial dose) in both egg yolk and albumen. First eggs were collected about 8 h after dosing; the second-day eggs were collected during 8-h period after the second dose. Radioactive residues reached a maximum on the fifth day of dosing in albumen, whereas on the second day of withdrawal in egg yolk, the peak TRR levels in albumen were about threefold higher than in yolk. Thereafter, the TRR levels declined rapidly in albumen and were detectable up to withdrawal day 6, whereas the TRR levels in egg yolk declined more slowly and were detectable up to withdrawal day 10. High-performance liquid chromatography analysis indicated that the parent drug sulfaquinoxaline was the major component in both the egg albumen and yolk. Additionally, this work suggests that egg yolk is the appropriate matrix for monitoring SQX residues PMID:15204532</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.2151L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.2151L"><span id="translatedtitle">Multi-isotope comparison of 3He, 21Ne, and <span class="hlt">36</span><span class="hlt">Cl</span> moraine ages from the high-altitude central Puna Plateau, NW Argentina (24°S)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Luna, Lisa; Bookhagen, Bodo; Niedermann, Samuel; Merchel, Silke; Rugel, Georg; Scharf, Andreas; Strecker, Manfred</p> <p>2016-04-01</p> <p>Glacial deposits on the high-altitude, arid Puna Plateau of northwestern Argentina document past changes in climate, but the associated geomorphic features have never been directly dated. The plateau is situated in the "Arid Diagonal," the hyper-arid transition zone between the Westerlies precipitation dominated southern Andes, and the South American Summer Monsoon controlled central Andes. Despite the climatically critical position of the Puna Plateau, paleoclimate data for the region is extremely sparse. This study provides direct age control of glacial moraine deposits from the central Puna Plateau (24°S) at elevations of 4500-5000 m through cosmogenic surface exposure dating. The volcanic lithologies of the deposits additionally allow for comparison of production rates from multiple cosmogenic isotope systems at low latitude and high elevation. Moraine boulders were dated using cosmogenic 3He from pyroxene, 21Ne from quartz, and <span class="hlt">36</span><span class="hlt">Cl</span> from feldspars. Preliminary data suggests that the most extensive glaciation occurred more than 80 ka ago, and that an additional prominent advance occurred at ~39 ka. In addition, comparison of isotope production ratios from low latitude and high elevation will contribute to better constrained production rates, particularly for <span class="hlt">36</span><span class="hlt">Cl</span>, for which global production rate estimates are highly variable. This study documents Quaternary climate changes on the Puna Plateau, while at the same time improving production rate agreement between multiple cosmogenic isotope systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015A%26A...578A.113K&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015A%26A...578A.113K&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">26</span><span class="hlt">Al</span> kinematics: superbubbles following the spiral arms?. Constraints from the statistics of star clusters and HI supershells</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Krause, Martin G. H.; Diehl, Roland; Bagetakos, Yiannis; Brinks, Elias; Burkert, Andreas; Gerhard, Ortwin; Greiner, Jochen; Kretschmer, Karsten; Siegert, Thomas</p> <p>2015-06-01</p> <p>Context. High-energy resolution spectroscopy of the 1.8 MeV radioactive decay line of <span class="hlt">26</span><span class="hlt">Al</span> with the SPI instrument onboard the INTEGRAL satellite has recently revealed that diffuse <span class="hlt">26</span><span class="hlt">Al</span> has higher velocities than other components of the interstellar medium in the Milky Way. <span class="hlt">26</span><span class="hlt">Al</span> shows Galactic rotation in the same sense as the stars and other gas tracers, but reaches excess velocities of up to 300 km s-1. Aims: We investigate whether this result can be understood in the context of superbubbles, taking into account the statistics of young star clusters and HI supershells as well as the association of young star clusters with spiral arms. Methods: We derived energy output and <span class="hlt">26</span><span class="hlt">Al</span> mass of star clusters as a function of the cluster mass by population synthesis from stellar evolutionary tracks of massive stars. Using the limiting cases of weakly and strongly dissipative superbubble expansion, we linked this to the size distribution of HI supershells and assessed the properties of possible <span class="hlt">26</span><span class="hlt">Al</span>-carrying superbubbles. Results: <span class="hlt">26</span><span class="hlt">Al</span> is produced by star clusters of all masses above ≈200 M⊙, is roughly equally contributed over a logarithmic star cluster mass scale and strongly linked to the injection of feedback energy. The observed superbubble size distribution cannot be related to the star cluster mass function in a straightforward manner. To avoid the added volume of all superbubbles exceeding the volume of the Milky Way, individual superbubbles have to merge frequently. If any two superbubbles merge, or if <span class="hlt">26</span><span class="hlt">Al</span> is injected off-centre into a larger HI supershell, we expect the hot <span class="hlt">26</span><span class="hlt">Al</span>-carrying gas to obtain velocities of the order of the typical sound speed in superbubbles, ≈300 km s-1 before decay. For star formation coordinated by the spiral arm pattern which, inside co-rotation, is overtaken by the faster moving stars and gas, outflows from spiral arm star clusters would preferentially flow into the cavities that are inflated by previous star formation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NIMPB.361..346F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NIMPB.361..346F"><span id="translatedtitle">Towards improvement of aluminium assay in quartz for in situ cosmogenic <span class="hlt">26</span><span class="hlt">Al</span> analysis at ANSTO</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fujioka, Toshiyuki; Fink, David; Mifsud, Charles</p> <p>2015-10-01</p> <p>Accuracy and precision in the measurement of natural aluminium abundances in quartz can affect the reliability of <span class="hlt">26</span><span class="hlt">Al</span> exposure dating and <span class="hlt">26</span><span class="hlt">Al</span>/10Be burial dating. At ANSTO, aliquots extracted from the HF solutions of dissolved quartz are treated in our laboratory, whereas ICP-OES analysis is performed at a commercial laboratory. The long-term inter-run reproducibility of our in-house standards show a limiting precision in Al measurements of 3-4% (1σ), which is lower than the claimed precision of Al analysis by ICP-OES. This indicates that unaccounted random errors are incorporated during our aliquot preparation. In this study, we performed several controlled tests to investigate effects of possible inconsistencies and variances during our aliquot preparation procedure. The results indicate that our procedure is robust against any subtle change in the preparation procedure, e.g., fuming temperatures, fuming reagents, and drying conditions. We found that the density of the solutions dispatched for ICP analysis is occasionally variable due to the presence of residual fuming reagents in the solution. A comparison of the results between the calibration curve and standard addition methods show that the former results are consistently lower than the latter by up to ∼14%. Similar offsets have been reported by previous studies. The reason for these discrepancies is mostly likely matrix effect, which is not accounted for by the calibration curve method. Further tests by varying matrix with impurities such as HF, HClO4, H2SO4 and Si identified that Si could cause lower offset in Al measurements; however, our ICP solutions are confirmed to be free from Si and the cause of matrix effect remains to be investigated. Hence, care must be taken for the measurement of Al concentrations in quartz by ICP-OES, either by ensuring that matrix effect is fully accounted for or by routinely employing standard additions when required.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004NIMPB.223..770Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004NIMPB.223..770Z"><span id="translatedtitle">Forensic applications of <span class="hlt">14</span><span class="hlt">C</span> bomb-pulse dating</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zoppi, U.; Skopec, Z.; Skopec, J.; Jones, G.; Fink, D.; Hua, Q.; Jacobsen, G.; Tuniz, C.; Williams, A.</p> <p>2004-08-01</p> <p>After a brief review of the basics of <span class="hlt">14</span><span class="hlt">C</span> bomb-pulse dating, this paper presents two unique forensic applications. Particular attention is dedicated to the use of the <span class="hlt">14</span><span class="hlt">C</span> bomb-pulse to establish the time of harvest of illicit drugs such as heroin and opium. Preliminary measurements of <span class="hlt">14</span><span class="hlt">C</span> concentrations in milligram samples taken from seized drugs are presented. <span class="hlt">14</span><span class="hlt">C</span> bomb-pulse dating can determine whether drug distribution originates from stockpiles or recent manufacture, and support the action of law enforcement authorities against criminal organisations involved in drug trafficking. In addition, we describe the dating of wine vintages for a number of authenticated single label vintage red wines from the Barossa Valley - South Australia. Our results show that radiocarbon dating can be used to accurately determine wine vintages and therefore reveal the addition of unrelated materials of natural and synthetic origin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013NIMPB.294..252G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013NIMPB.294..252G"><span id="translatedtitle">Effect of HF leaching on <span class="hlt">14</span><span class="hlt">C</span> dates of pottery</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Goslar, Tomasz; Kozłowski, Janusz; Szmyt, Marzena; Czernik, Justyna</p> <p>2013-01-01</p> <p>This paper presents the experiments with <span class="hlt">14</span><span class="hlt">C</span> dating of two potsherds, which contained carbon dispersed rather homogeneously in their clay fabric. After AAA treatment, the potsherds still appeared to be contaminated with young carbon, presumably connected with humic acids. To make removal of humic acids more effective, we treated the sherds with HF acid of different concentration. The <span class="hlt">14</span><span class="hlt">C</span> results obtained demonstrate that HF treatment indeed helps to remove humic contaminants, but it also mobilizes carbon bound to raw clay, which may make <span class="hlt">14</span><span class="hlt">C</span> dates too old. We conclude therefore, that using a simple combination of HF and AAA treatment seems insufficient in reliable <span class="hlt">14</span><span class="hlt">C</span> dating of carbon homogeneously dispersed in the volume of potsherds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/pages/biblio/1255183-feasibility-isobaric-suppression-via-post-accelerator-foil-stripping-measurement-feasibility-isobaric-suppression-via-post-accelerator-foil-stripping-measurement','SCIGOV-DOEP'); return false;" href="http://www.osti.gov/pages/biblio/1255183-feasibility-isobaric-suppression-via-post-accelerator-foil-stripping-measurement-feasibility-isobaric-suppression-via-post-accelerator-foil-stripping-measurement"><span id="translatedtitle">The feasibility of isobaric suppression of 26Mg via post-accelerator foil stripping for the measurement of <span class="hlt">26</span><span class="hlt">Al</span> [The feasibility of isobaric suppression of 26Mg via post-accelerator foil stripping for the measurement of <span class="hlt">26</span><span class="hlt">Al</span>.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Tumey, Scott J.; Brown, Thomas A.; Finkel, Robert C.; Rood, Dylan H.</p> <p>2012-09-13</p> <p>Most accelerator mass spectrometry measurements of <span class="hlt">26</span><span class="hlt">Al</span> utilize the Al- ion despite lower source currents compared with AlO- since the stable isobar 26Mg does not form elemental negative ions. A gas-filled magnet allows sufficient suppression of 26Mg thus enabling the use of the more intense <span class="hlt">26</span><span class="hlt">Al</span>O- ion. However, most AMS systems do not include a gas-filled magnet. We therefore explored the feasibility of suppressing 26Mg by using a post-accelerator stripping foil. With this approach, combined with the use of alternative cathode matrices, we were able to suppress 26Mg by a factor of twenty. This suppression was insufficient to enable themore » use of <span class="hlt">26</span><span class="hlt">Al</span>O-, however further refinement of our system may permit its use in the future.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014GMDD....7.7033K&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014GMDD....7.7033K&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">14</span><span class="hlt">C</span>-age tracers in global ocean circulation models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koeve, W.; Wagner, H.; Kähler, P.; Oschlies, A.</p> <p>2014-10-01</p> <p>The natural abundance of <span class="hlt">14</span><span class="hlt">C</span> in total CO2 dissolved in seawater is a property applied to evaluate the water age structure and circulation in the ocean and in ocean models. In this study we use three different representations of the global ocean circulation augmented with a suite of idealised tracers to study the potential and limitations of using natural <span class="hlt">14</span><span class="hlt">C</span> to determine water age, the time elapsed since a body of water had contact with the atmosphere. We find that, globally, bulk <span class="hlt">14</span><span class="hlt">C</span>-age is dominated by two equally important components, one associated with aging, i.e. the time component of circulation and one associated with a "preformed <span class="hlt">14</span><span class="hlt">C</span>-age". This latter quantity exists because of the slow and incomplete atmosphere/ocean equilibration of <span class="hlt">14</span><span class="hlt">C</span> in particular in high latitudes where many water masses form. The relative contribution of the preformed component to bulk <span class="hlt">14</span><span class="hlt">C</span>-age varies regionally within a given model, but also between models. Regional variability, e.g. in the Atlantic Ocean is associated with the mixing of waters with very different end members of preformed <span class="hlt">14</span><span class="hlt">C</span>-age. In the Atlantic, variations in the preformed component over space and time mask the circulation component to an extent that its patterns are not detectable from bulk <span class="hlt">14</span><span class="hlt">C</span>-age alone. Between models the variability of age can also be considerable (factor of 2), related to the combinations of physical model parameters, which influence circulation dynamics, and gas exchange in the models. The preformed component was found to be very sensitive to gas exchange and moderately sensitive to ice cover. In our model evaluation exercise, the choice of the gas exchange constant from within the current range of uncertainty had such a strong influence on preformed and bulk <span class="hlt">14</span><span class="hlt">C</span>-age that if model evaluation would be based on bulk <span class="hlt">14</span><span class="hlt">C</span>-age it could easily impair the evaluation and tuning of a models circulation on global and regional scales. Based on the results of this study, we propose that considering</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/835912','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/835912"><span id="translatedtitle">Activation Measurements for Thermal Neutrons, U.S. Measurements of <span class="hlt">36</span><span class="hlt">Cl</span> in Mineral Samples from Hiroshima and Nagasaki; and Measurement of 63 Ni in Copper Samples From Hiroshima by Accelerator Mass Spectrometry</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tore Straume; Alfredo A. Marchetti; Stephen D. Egbert; James A. Roberts; Ping Men; Shoichiro Fujita; Kiyoshi Shizuma; Masaharu Hoshi; G. Rugel; W. Ruhm; G. Korschinek; J. E. McAninch; K. L. Carroll; T. Faestermann; K. Knie; R. E. Martinelli; A. Wallner; C. Wallner</p> <p>2005-01-14</p> <p>The present paper presents the {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> measurement effort in the US. A large number of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> measurements have been made in both granite and concrete samples obtained from various locations and distances in Hiroshima and Nagasaki. These measurements employed accelerator mass spectrometry (AMS) to quantify the number of atoms of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> per atom of total Cl in the sample. Results from these measurements are presented here and discussed in the context of the DS02 dosimetry reevaluation effort for Hiroshima and Nagasaki atomic-bomb survivors. The production of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> by bomb neutrons in mineral samples from Hiroshima and Nagasaki was primarily via the reaction {sup 35}Cl(n,{gamma}){sup <span class="hlt">36</span>}<span class="hlt">Cl</span>. This reaction has a substantial thermal neutron cross-section (43.6 b at 0.025 eV) and the product has a long half-life (301,000 y). hence, it is well suited for neutron-activation detection in Hiroshima and Nagasaki using AMS more than 50 years after the bombings. A less important reaction for bomb neutrons, {sup 39}K(n,{alpha}){sup <span class="hlt">36</span>}<span class="hlt">Cl</span>, typically produces less than 10% of the {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> in mineral samples such as granite and concrete, which contain {approx} 2% potassium. In 1988, only a year after the publication of the DS86 final report (Roesch 1987), it was demonstrated experimentally that {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> measured using AMS should be able to detect the thermal neutron fluences at the large distances most relevant to the A-bomb survivor dosimetry. Subsequent measurements in mineral samples from both Hiroshima and Nagasaki validated the experimental findings. The potential utility of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> as a thermal neutron detector in Hiroshima was first presented by Haberstock et al. who employed the Munich AMS facility to measure {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl ratios in a gravestone from near the hypocenter. That work subsequently resulted in an expanded {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> effort in Germany that paralleled the US work. More recently, there have also been {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> measurements made by a Japanese</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/656073','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/656073"><span id="translatedtitle">Intramolecular labelling of sucrose made by leaves from [<span class="hlt">14</span><span class="hlt">C</span>)carbon dioxide or [3-<span class="hlt">14</span><span class="hlt">C</span>]serine.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bird, I F; Cornelius, M J; Keys, A J; Whittingham, C P</p> <p>1978-04-15</p> <p>Pea leaves were illuminated in air containing 150 or 1000p.p.m. of 14CO2 for various times. Alternatively, segments of wheat leaves were supplied with [3-<span class="hlt">14</span><span class="hlt">C</span>]serine for 40 min in the light in air with 145, 326 or 944p.p.m. of 12CO2. Sucrose was extracted from the leaf material, hydrolysed with invertase, and <span class="hlt">14</span><span class="hlt">C</span> in the pairs of carbon atoms C-3+C-4, C-2+C-5 and C-1+C-6 in the glucose moiety was measured. The results obtained after metabolism of 14CO2 were consistent with the operation of the photosynthetic carbon-reduction cycle; the effects of CO2 concentration on distribution of <span class="hlt">14</span><span class="hlt">C</span> in the carbon chain of glucose after metabolism of [3-<span class="hlt">14</span><span class="hlt">C</span>]serine is more easily explained by metabolism through the glycollate pathway than by the carbon-reduction cycle. PMID:656073</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70029102','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70029102"><span id="translatedtitle">Dating Plio-Pleistocene glacial sediments using the cosmic-ray-produced radionuclides 10Be and <span class="hlt">26</span><span class="hlt">Al</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Balco, G.; Stone, J.O.H.; Jennings, C.</p> <p>2005-01-01</p> <p>We use the cosmic-ray-produced radionuclides <span class="hlt">26</span><span class="hlt">Al</span> and 10Be to date Plio-Pleistocene glacial sediment sequences. These two nuclides are produced in quartz at a fixed ratio, but have different decay constants. If a sample is exposed at the surface for a time and then buried by overburden and thus removed from the cosmic-ray flux, the <span class="hlt">26</span><span class="hlt">Al</span>/10Be ratio is related to the duration of burial. We first attempted to date pre-Wisconsinan tills by measuring <span class="hlt">26</span><span class="hlt">Al</span> and 10Be in fluvial sediments beneath them and applying the method of "burial dating," which previous authors have used to date river sediment carried into caves. This method, however, requires simplifying assumptions about the <span class="hlt">26</span><span class="hlt">Al</span> and 10Be concentrations in the sediment at the time of burial. We show that these assumptions are not valid for river sediment in glaciated regions. <span class="hlt">26</span><span class="hlt">Al</span> and 10Be analyses of such sediment do not provide accurate ages for these tills, although they do yield limiting ages in some cases. We overcome this difficulty by instead measuring <span class="hlt">26</span><span class="hlt">Al</span> and 10Be in quartz from paleosols that are buried by tills. We use a more general mathematical approach to determine the initial nuclide concentrations in the paleosol at the time it was buried, as well as the duration of burial. This technique provides a widely applicable improvement on other means of dating Plio-Pleistocene terrestrial glacial sediments, as well as a framework for applying cosmogenic-nuclide dating techniques in complicated stratigraphic settings. We apply it to pre-Wisconsinan glacial sediment sequences in southwest Minnesota and eastern South Dakota. Pre-Wisconsinan tills underlying the Minnesota River Valley were deposited 0.5 to 1.5 Ma, and tills beneath the Prairie Coteau in eastern South Dakota and adjacent Minnesota were deposited 1 to 2 Ma.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18617793','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18617793"><span id="translatedtitle">Characterization of <span class="hlt">14</span><span class="hlt">C</span> in Swedish light water reactors.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Magnusson, Asa; Aronsson, Per-Olof; Lundgren, Klas; Stenström, Kristina</p> <p>2008-08-01</p> <p>This paper presents the results of a 4-y investigation of <span class="hlt">14</span><span class="hlt">C</span> in different waste streams of both boiling water reactors (BWRs) and pressurized water reactors (PWRs). Due to the potential impact of <span class="hlt">14</span><span class="hlt">C</span> on human health, minimizing waste and releases from the nuclear power industry is of considerable interest. The experimental data and conclusions may be implemented to select appropriate waste management strategies and practices at reactor units and disposal facilities. Organic and inorganic <span class="hlt">14</span><span class="hlt">C</span> in spent ion exchange resins, process water systems, ejector off-gas and replaced steam generator tubes were analyzed using a recently developed extraction method. Separate analysis of the chemical species is of importance in order to model and predict the fate of <span class="hlt">14</span><span class="hlt">C</span> within process systems as well as in dose calculations for disposal facilities. By combining the results of this investigation with newly calculated production rates, mass balance assessments were made of the <span class="hlt">14</span><span class="hlt">C</span> originating from production in the coolant. Of the <span class="hlt">14</span><span class="hlt">C</span> formed in the coolant of BWRs, 0.6-0.8% was found to be accumulated in the ion exchange resins (core-specific production rate in the coolant of a 2,500 MWth BWR calculated to be 580 GBq GW(e)(-1) y(-1)). The corresponding value for PWRs was 6-10% (production rate in a 2,775 MWth PWR calculated to be 350 GBq GW(e)(-1) y(-1)). The <span class="hlt">14</span><span class="hlt">C</span> released with liquid discharges was found to be insignificant, constituting less than 0.5% of the production in the coolant. The stack releases, routinely measured at the power plants, were found to correspond to 60-155% of the calculated coolant production, with large variations between the BWR units.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4080803','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4080803"><span id="translatedtitle"><span class="hlt">14</span><span class="hlt">C</span> Analysis of Protein Extracts from Bacillus Spores</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Cappucio, Jenny A.; Sarachine Falso, Miranda J.; Kashgarian, Michaele; Buchholz, Bruce A.</p> <p>2014-01-01</p> <p>Investigators of bioagent incidents or interdicted materials need validated, independent analytical methods that will allow them to distinguish between recently made bioagent samples versus material drawn from the archives of a historical program. Heterotrophic bacteria convert the carbon in their food sources, growth substrate or culture media, into the biomolecules they need. The F<span class="hlt">14</span><span class="hlt">C</span> (fraction modern radiocarbon) of a variety of media, Bacillus spores, and separated proteins from Bacillus spores was measured by accelerator mass spectrometry (AMS). AMS precisely measures F<span class="hlt">14</span><span class="hlt">C</span> values of biological materials and has been used to date the synthesis of biomaterials over the bomb pulse era (1955 to present). The F<span class="hlt">14</span><span class="hlt">C</span> of Bacillus spores reflects the radiocarbon content of the media in which they were grown. In a survey of commercial media we found that the F<span class="hlt">14</span><span class="hlt">C</span> value indicated that carbon sources for the media were alive within about a year of the date of manufacture and generally of terrestrial origin. Hence, bacteria and their products can be dated using their <span class="hlt">14</span><span class="hlt">C</span> signature. Bacillus spore samples were generated onsite with defined media and carbon free purification and also obtained from archived material. Using mechanical lysis and a variety of washes with carbon free acids and bases, contaminant carbon was removed from soluble proteins to enable accurate <span class="hlt">14</span><span class="hlt">C</span> bomb-pulse dating. Since media is contemporary, <span class="hlt">14</span><span class="hlt">C</span> bomb-pulse dating of isolated soluble proteins can be used to distinguish between historical archives of bioagents and those produced from recent media. PMID:24814329</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/18617793','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/18617793"><span id="translatedtitle">Characterization of <span class="hlt">14</span><span class="hlt">C</span> in Swedish light water reactors.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Magnusson, Asa; Aronsson, Per-Olof; Lundgren, Klas; Stenström, Kristina</p> <p>2008-08-01</p> <p>This paper presents the results of a 4-y investigation of <span class="hlt">14</span><span class="hlt">C</span> in different waste streams of both boiling water reactors (BWRs) and pressurized water reactors (PWRs). Due to the potential impact of <span class="hlt">14</span><span class="hlt">C</span> on human health, minimizing waste and releases from the nuclear power industry is of considerable interest. The experimental data and conclusions may be implemented to select appropriate waste management strategies and practices at reactor units and disposal facilities. Organic and inorganic <span class="hlt">14</span><span class="hlt">C</span> in spent ion exchange resins, process water systems, ejector off-gas and replaced steam generator tubes were analyzed using a recently developed extraction method. Separate analysis of the chemical species is of importance in order to model and predict the fate of <span class="hlt">14</span><span class="hlt">C</span> within process systems as well as in dose calculations for disposal facilities. By combining the results of this investigation with newly calculated production rates, mass balance assessments were made of the <span class="hlt">14</span><span class="hlt">C</span> originating from production in the coolant. Of the <span class="hlt">14</span><span class="hlt">C</span> formed in the coolant of BWRs, 0.6-0.8% was found to be accumulated in the ion exchange resins (core-specific production rate in the coolant of a 2,500 MWth BWR calculated to be 580 GBq GW(e)(-1) y(-1)). The corresponding value for PWRs was 6-10% (production rate in a 2,775 MWth PWR calculated to be 350 GBq GW(e)(-1) y(-1)). The <span class="hlt">14</span><span class="hlt">C</span> released with liquid discharges was found to be insignificant, constituting less than 0.5% of the production in the coolant. The stack releases, routinely measured at the power plants, were found to correspond to 60-155% of the calculated coolant production, with large variations between the BWR units. PMID:18617793</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23811127','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23811127"><span id="translatedtitle">Translocation of (125)I, (75)Se and (<span class="hlt">36</span>)<span class="hlt">Cl</span> to edible parts of radish, potato and green bean following wet foliar contamination under field conditions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Henner, P; Hurtevent, P; Thiry, Y; Levchuk, S; Yoschenko, V; Kashparov, V</p> <p>2013-10-01</p> <p>Specific translocation factor values (ftr) for (129)I, (79)Se and (<span class="hlt">36</span>)<span class="hlt">Cl</span> following foliar transfer are still missing from the IAEA reference databases. The translocation of the short-lived isotopes, (125)I, (75)Se, and (<span class="hlt">36</span>)<span class="hlt">Cl</span>, to radish, potato and green bean edible parts was measured under field conditions following acute and chronic wet foliar contamination at various plant growth stages in the absence of leaching caused by rain. The translocation factors obtained for (125)I ranged from 0.8 to 2.6% for radish, from 0.1 to 2.3% for potato and from 0.1 to 2.6% for bean. The translocation factors obtained for (75)Se ranged from 6.3 to 21% for radish, from 1.6 to 32.6% for potato and from 7.7 to 22.8% for bean (values similar to Cs or even higher). The translocation factors obtained for (<span class="hlt">36</span>)<span class="hlt">Cl</span> were close to those for (75)Se and ranged from 4.3 to 28.8% for radish, from 0.5 to 31.5% for potato and from 4.3 to 16.3% for bean. Iodide showed the lowest apparent mobility because of its preferential fixation in or on the leaves and a significant amount was probably volatilized. Selenite internal transfer was significant and possibly followed the sulfur metabolic pathway. Chloride was very mobile and quickly diffused throughout the plant. The translocation factors varied with the growth stage and depended on the development state of the edible tissue and its associated sink strength for nutrients and assimilates. For radish, translocation was high during the early vegetative stages. For potato, wheat and bean, a major peak in translocation was seen during the flowering growth stage and the concomitant growth of potato tubers. An additive effect of successive contamination events on translocated elements was shown in radish but not in bean and potato. The highest translocation value obtained for an acute contamination event was shown to be an adequate, conservative indicator of chronic contamination in absence of specific values. Due to the absence of rain leaching during</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1814251Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1814251Y"><span id="translatedtitle">Deriving earthquake history of the Knidos Fault Zone, SW Turkey, using cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> surface exposure dating of the fault scarp.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yildirim, Cengiz; Ersen Aksoy, Murat; Akif Sarikaya, Mehmet; Tuysuz, Okan; Genc, S. Can; Ertekin Doksanalti, Mustafa; Sahin, Sefa; Benedetti, Lucilla; Tesson, Jim; Aster Team</p> <p>2016-04-01</p> <p>Formation of bedrock fault scarps in extensional provinces is a result of large and successive earthquakes that ruptured the surface several times. Extraction of seismic history of such faults is critical to understand the recurrence intervals and the magnitude of paleo-earthquakes and to better constrain the regional seismic hazard. Knidos on the Datca Peninsula (SW Turkey) is one of the largest cities of the antique times and sits on a terraced hill slope formed by en-echelon W-SW oriented normal faults. The Datça Peninsula constitutes the southern boundary of the Gulf of Gökova, one of the largest grabens developed on the southernmost part of the Western Anatolian Extensional Province. Our investigation relies on cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> surface exposure dating of limestone faults scarps. This method is a powerful tool to reconstruct the seismic history of normal faults (e.g. Schlagenhauf et al 2010, Benedetti et al. 2013). We focus on one of the most prominent fault scarp (hereinafter Mezarlık Fault) of the Knidos fault zone cutting through the antique Knidos city. We collected 128 pieces of tablet size (10x20cm) 3-cm thick samples along the fault dip and opened 4 conventional paleoseismic trenches at the base of the fault scarp. Our <span class="hlt">36</span><span class="hlt">Cl</span> concentration profile indicates that 3 to 4 seismic events ruptured the Mezarlık Fault since Last Glacial Maximum (LGM). The results from the paleoseismic trenching are also compatible with <span class="hlt">36</span><span class="hlt">Cl</span> results, indicating 3 or 4 seismic events that disturbed the colluvium deposited at the base of the scarp. Here we will present implications for the seismic history and the derived slip-rate of the Mezarlık Fault based on those results. This project is supported by The Scientific and Technological Research Council of Turkey (TUBITAK, Grant number: 113Y436) and it was conducted with the Decision of the Council of Ministers with No. 2013/5387 on the date 30.09.2013 and was done with the permission of Knidos Presidency of excavation in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001M%26PS...36..963L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001M%26PS...36..963L"><span id="translatedtitle">Cosmic-ray production rates of He-, Ne- and Ar-isotopes in H-chondrites based on <span class="hlt">36</span><span class="hlt">Cl</span>-36Ar-ages</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Leya, I.; Graf, Th.; Nishiizumi, K.; Wieler, R.</p> <p>2001-07-01</p> <p>We present the concentrations and isotopic compositions of He, Ne, and Ar for non-magnetic fractions and bulk samples of 17 H-chondrites which were recently investigated for their <span class="hlt">36</span><span class="hlt">Cl</span>-36Ar cosmic-ray exposure ages (Graf et al., 2001). All selected meteorites are observed falls with cosmic-ray exposure ages close to the 7 Ma peak. The rare gas data are consistent with 10Be and <span class="hlt">36</span><span class="hlt">Cl</span> production rates in the metal phase. Remarkably, only one out of the 17 H-chondrites, Bath, shows clear indications for a complex exposure history. Based on rare gas concentrations and <span class="hlt">36</span><span class="hlt">Cl</span>-36Ar exposure ages, 21Ne production rates as a function of 22Ne/21Ne and a mean 38Ar production rate are determined. The results confirm model calculations which predict that the relationship between 21Ne production rates and 22Ne/21Ne is ambiguous for high shielding. Besides the mean 38Ar production rate we also give production rate ratios P(38Ar from Ca) / P(38Ar from Fe). They vary between 10 and 77, showing no significant correlation with 38Ar-concentrations or 22Ne/21Ne. By investigating the metal-separates, Graf et al. (2001) found significant 3He deficits for six out of the 17 meteorites. For the non-magnetic fractions and bulk samples investigated here the data points in a 3He/21Ne versus 22Ne/21Ne diagram plot in the area defined by most of the H-chondrites. This means that 3He deficits in the metal phase are much more pronounced than in silicate minerals and we will argue that 3H diffusive losses in meteorites should be the rule rather than the exception. The 21Ne exposure ages, calculated on the basis of modeled 21Ne production rates, confirm the assumption by Graf et al. (2001) that the H5-chondrites with low 3He/38Ar in the metal formed in a separate event than those with normal 3He/38Ar ratios. The data can best be interpreted by assuming that the prominent 7 Ma exposure age peak of the H-chondrites is due to at least two events about 7.0 and 7.6 Ma ago.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70024947','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70024947"><span id="translatedtitle">Pyrolysis-combustion <span class="hlt">14</span><span class="hlt">C</span> dating of soil organic matter</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Wang, Hongfang; Hackley, Keith C.; Panno, S.V.; Coleman, D.D.; Liu, J.C.-L.; Brown, J.</p> <p>2003-01-01</p> <p>Radiocarbon (<span class="hlt">14</span><span class="hlt">C</span>) dating of total soil organic matter (SOM) often yields results inconsistent with the stratigraphic sequence. The onerous chemical extractions for SOM fractions do not always produce satisfactory <span class="hlt">14</span><span class="hlt">C</span> dates. In an effort to develop an alternative method, the pyrolysis-combustion technique was investigated to partition SOM into pyrolysis volatile (Py-V) and pyrolysis residue (Py-R) fractions. The Py-V fractions obtained from a thick glacigenic loess succession in Illinois yielded <span class="hlt">14</span><span class="hlt">C</span> dates much younger but more reasonable than the counterpart Py-R fractions for the soil residence time. Carbon isotopic composition (??13C) was heavier in the Py-V fractions, suggesting a greater abundance of carbohydrate- and protein-related constituents, and ??13C was lighter in the Py-R fractions, suggesting more lignin- and lipid-related constituents. The combination of <span class="hlt">14</span><span class="hlt">C</span> dates and ??13C values indicates that the Py-V fractions are less biodegradation resistant and the Py-R fractions are more biodegradation resistant. The pyrolysis-combustion method provides a less cumbersome approach for <span class="hlt">14</span><span class="hlt">C</span> dating of SOM fractions. With further study, this method may become a useful tool for analyzing unlithified terrestrial sediments when macrofossils are absent. ?? 2003 University of Washington. Published by Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPhCS.718f2018E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPhCS.718f2018E"><span id="translatedtitle">Measuring the <span class="hlt">14</span><span class="hlt">C</span> content in liquid scintillators</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Enqvist, T.; Barabanov, I. R.; Bezrukov, L. B.; Gangapshev, A. M.; Gavrilyuk, Y. M.; Grishina, V. Yu; Gurentsov, V. I.; Hissa, J.; Joutsenvaara, J.; Kazalov, V. V.; Krokhaleva, S.; Kutuniva, J.; Kuusiniemi, P.; Kuzminov, V. V.; Kurlovich, A. S.; Loo, K.; Lubsandorzhiev, B. K.; Lubsandorzhiev, S.; Morgalyuk, V. P.; Novikova, G. Y.; Pshukov, A. M.; Sinev, V. V.; Słupecki, M.; Trzaska, W. H.; Umerov, Sh I.; Veresnikova, A. V.; Virkajärvi, A.; Yanovich, Y. A.; Zavarzina, V. P.</p> <p>2016-05-01</p> <p>We are going to perform a series of measurements where the <span class="hlt">14</span><span class="hlt">C</span>/12 C ratio will be measured from several liquid scintillator samples with a dedicated setup. The setup is designed with the aim of measuring ratios smaller than 10-18. Measurements take place in two underground laboratories: in the Baksan Neutrino Observatory, Russia and in the Pyhäsalmi mine, Finland. In Baksan the measurements started in 2015 and in Pyhäsalmi they start in the beginning of 2015. In order to fully understand the operation of the setup and its background contributions a development of simulation packages has also been started. Low-energy neutrino detection with a liquid scintillator requires that the intrinsic <span class="hlt">14</span><span class="hlt">C</span> content in the liquid is extremely low. In the Borexino CTF detector at Gran Sasso, Italy the <span class="hlt">14</span><span class="hlt">C</span>/12C ratio of 2 × 10-18 has been achieved being the lowest <span class="hlt">14</span><span class="hlt">C</span> concentration ever measured. In principle, the older the oil or gas source that the liquid scintillator is derived of and the deeper it situates, the smaller the <span class="hlt">14</span><span class="hlt">C</span>/12C ratio is supposed to be. This, however, is not generally the case, and the ratio is probably determined by the U and Th content of the local environment.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_8 --> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004E%26PSL.225..163P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004E%26PSL.225..163P"><span id="translatedtitle">Slip history of the Magnola fault (Apennines, Central Italy) from <span class="hlt">36</span><span class="hlt">Cl</span> surface exposure dating: evidence for strong earthquakes over the Holocene</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Palumbo, Luigi; Benedetti, Lucilla; Bourlès, Didier; Cinque, Aldo; Finkel, Robert</p> <p>2004-08-01</p> <p>To better understand the mechanics of deformation in the Mediterranean and the role that the convergence between Africa and Europe plays, it is necessary to know the deformation field at different time scales. Here we use in situ <span class="hlt">36</span><span class="hlt">Cl</span> surface exposure dating of exposed bedrock fault scarps to determine earthquake time-slip histories and to quantify slip rates over the last several thousand years. This information allows us to delineate the seismic history of normal faulting within the Mediterranean area over that time period. We have studied the limestone scarp produced by the Magnola fault in the Central Apennines, Italy. The Magnola fault, in the Fucino area, is an active, 15-km long, normal fault striking WNW and dipping SSW. The range front morphology, characterised by steep triangular facets separated by V-shaped valleys and wine-glass canyons, suggests that the Magnola fault has been active for at least the last several hundred thousand years. At the base of the facets, the fault cuts limestone bedrock to produce a well-preserved normal fault scarp 10 to 12 m high. The distribution of <span class="hlt">36</span><span class="hlt">Cl</span> concentration versus the height along that scarp is best explained by a minimum of five and a maximum of seven successive earthquake exhumations, with slips varying between 1.5 and 3 m. An age of ˜5 ka at the base of the scarp and of ˜12 ka at the top yields a slip rate of ˜0.8 mm/year. The absence of any event on this fault during the last 5000 years suggests either that a future event is imminent on the Magnola fault or that the fault has entered a quiescent period with much longer recurrence time. Our study confirms that the Magnola fault scarp is post-glacial and supports the hypothesis that similar scarps in the Mediterranean are also post-glacial.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/20719246','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/20719246"><span id="translatedtitle">Low-level <span class="hlt">14</span><span class="hlt">C</span> measurements and Accelerator Mass Spectrometry</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Litherland, A.E.; Beukens, R.P.; Zhao, X.-L.; Kieser, W.E.; Gove, H.E.</p> <p>2005-09-08</p> <p>Accelerator Mass Spectrometry (AMS) and isotope enrichment were used in 1991 to estimate that the <span class="hlt">14</span><span class="hlt">C</span> content of methane in natural gas was {<=}1.6x10-18 of the total carbon. The low content of <span class="hlt">14</span><span class="hlt">C</span> in underground hydrocarbons was verified later in the remarkable results from the Borexino test scintillation counter for solar neutrino studies. Since then studies of the <span class="hlt">14</span><span class="hlt">C</span> background problem have demonstrated that much of the background originally observed in the AMS measurements can, in principle, be eliminated. However, many difficulties and other backgrounds are to be faced as the limit for AMS is pushed still further towards possibly a ratio of < 10-21. These will be discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeCoA.159..126B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeCoA.159..126B"><span id="translatedtitle">Rapid, high-resolution <span class="hlt">14</span><span class="hlt">C</span> chronology of ooids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Beaupré, Steven R.; Roberts, Mark L.; Burton, Joshua R.; Summons, Roger E.</p> <p>2015-06-01</p> <p>Ooids are small, spherical to ellipsoidal grains composed of concentric layers of CaCO3 that could potentially serve as biogeochemical records of the environments in which they grew. Such records, however, must be placed in the proper temporal context. Therefore, we developed a novel acidification system and employed an accelerator mass spectrometer (AMS) with a gas accepting ion source to obtain radiocarbon (<span class="hlt">14</span><span class="hlt">C</span>) chronologies extending radially through ooids within one 8-h workday. The method was applied to ooids from Highborne Cay, Bahamas and Shark Bay, Australia, yielding reproducible <span class="hlt">14</span><span class="hlt">C</span> chronologies, as well as constraints on the rates and durations of ooid growth and independent estimates of local <span class="hlt">14</span><span class="hlt">C</span> reservoir ages.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25706272','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25706272"><span id="translatedtitle"><span class="hlt">26</span><span class="hlt">Al</span>/10Be burial dating of Xujiayao-Houjiayao site in Nihewan Basin, northern China.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tu, Hua; Shen, Guanjun; Li, Haixu; Xie, Fei; Granger, Darryl E</p> <p>2015-01-01</p> <p>The Xujiayao-Houjiayao site in Nihewan Basin is among the most important Paleolithic sites in China for having provided a rich collection of hominin and mammalian fossils and lithic artifacts. Based on biostratigraphical correlation and exploratory results from a variety of dating methods, the site has been widely accepted as early Upper Pleistocene in time. However, more recent paleomagnetic analyses assigned a much older age of ∼500 ka (thousand years). This paper reports the application of <span class="hlt">26</span><span class="hlt">Al</span>/10Be burial dating as an independent check. Two quartz samples from a lower cultural horizon give a weighted mean age of 0.24 ± 0.05 Ma (million years, 1σ). The site is thus younger than 340 ka at 95% confidence, which is at variance with the previous paleomagnetic results. On the other hand, our result suggests an age of older than 140 ka for the site's lower cultural deposits, which is consistent with recent post-infrared infrared stimulated luminescence (pIR-IRSL) dating at 160-220 ka.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19279636','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19279636"><span id="translatedtitle">Age of Zhoukoudian Homo erectus determined with (<span class="hlt">26</span>)<span class="hlt">Al</span>/(10)Be burial dating.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shen, Guanjun; Gao, Xing; Gao, Bin; Granger, Darryl E</p> <p>2009-03-12</p> <p>The age of Zhoukoudian Homo erectus, commonly known as 'Peking Man', has long been pursued, but has remained problematic owing to the lack of suitable dating methods. Here we report cosmogenic (<span class="hlt">26</span>)<span class="hlt">Al</span>/(10)Be burial dating of quartz sediments and artefacts from the lower strata of Locality 1 in the southwestern suburb of Beijing, China, where early representatives of Zhoukoudian Homo erectus were discovered. This study marks the first radioisotopic dating of any early hominin site in China beyond the range of mass spectrometric U-series dating. The weighted mean of six meaningful age measurements, 0.77 +/- 0.08 million years (Myr, mean +/- s.e.m.), provides the best age estimate for lower cultural layers 7-10. Together with previously reported U-series dating of speleothem calcite and palaeomagnetic stratigraphy, as well as sedimentological considerations, these layers may be further correlated to S6-S7 in Chinese loess stratigraphy or marine isotope stages (MIS) 17-19, in the range of approximately 0.68 to 0.78 Myr ago. These ages are substantially older than previously supposed and may imply early hominin's presence at the site in northern China through a relatively mild glacial period corresponding to MIS 18.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4338100','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4338100"><span id="translatedtitle"><span class="hlt">26</span><span class="hlt">Al</span>/10Be Burial Dating of Xujiayao-Houjiayao Site in Nihewan Basin, Northern China</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Tu, Hua; Shen, Guanjun; Li, Haixu; Xie, Fei; Granger, Darryl E.</p> <p>2015-01-01</p> <p>The Xujiayao-Houjiayao site in Nihewan Basin is among the most important Paleolithic sites in China for having provided a rich collection of hominin and mammalian fossils and lithic artifacts. Based on biostratigraphical correlation and exploratory results from a variety of dating methods, the site has been widely accepted as early Upper Pleistocene in time. However, more recent paleomagnetic analyses assigned a much older age of ∼500 ka (thousand years). This paper reports the application of <span class="hlt">26</span><span class="hlt">Al</span>/10Be burial dating as an independent check. Two quartz samples from a lower cultural horizon give a weighted mean age of 0.24 ± 0.05 Ma (million years, 1σ). The site is thus younger than 340 ka at 95% confidence, which is at variance with the previous paleomagnetic results. On the other hand, our result suggests an age of older than 140 ka for the site’s lower cultural deposits, which is consistent with recent post-infrared infrared stimulated luminescence (pIR-IRSL) dating at 160–220 ka. PMID:25706272</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhDT.......297L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhDT.......297L"><span id="translatedtitle">Characterization of <span class="hlt">14</span><span class="hlt">C</span> in Neutron-Irradiated Graphite</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>LaBrier, Daniel Patrick</p> <p></p> <p>A long-term radiological concern regarding irradiated graphite waste is the presence of the radionuclide <span class="hlt">14</span><span class="hlt">C</span>. Recent studies suggest that a significant portion of <span class="hlt">14</span><span class="hlt">C</span> contamination present in reactor-irradiated graphite is concentrated on the surface and within near-surface layers. Methods for treating irradiated graphite waste (e.g. pyrolysis, oxidation) in order to remove <span class="hlt">14</span><span class="hlt">C</span>-bearing species from the bulk graphite are being investigated to lend guidance in optimizing long-term disposal strategies. Characterization studies were performed in order to determine the chemical nature of <span class="hlt">14</span><span class="hlt">C</span> on irradiated graphite surfaces. Samples of the nuclear-grade graphite NBG-25 were irradiated in a neutron flux of 10 14 n/cm2-s for 360 days at the Advanced Test Reactor (at the Idaho National Laboratory). Surface-sensitive analysis techniques (XPS, ToF-SIMS, SEM/EDS and Raman) were employed to determine the type, location and quantity of specific chemical species and bonds that were present on the surfaces of irradiated graphite samples. Several <span class="hlt">14</span><span class="hlt">C</span> precursor species were identified on the surfaces of irradiated NBG-25; the quantities of these species decrease at sub-surface depths, which, is consistent with the observation of high concentrations of <span class="hlt">14</span><span class="hlt">C</span> on the surfaces of graphite reactor components. The elevated presence of surface oxide complexes on irradiated NBG-25 surfaces was attributed directly to neutron irradiation. Pathways for the release of <span class="hlt">14</span><span class="hlt">C</span> were identified for irradiated NBG-25: carboxyls and lactones (14CO 2), and carbonyls, ethers and quinones (14CO). Increased amounts of C-O and C=O bonding were observed on irradiated NBG-25 surfaces (when compared to unirradiated samples) in the form of interlattice (e.g. ether) and dangling (e.g. carboxyl or quinone) bonds; the quantities of these bond types also decrease at sub-surface depths. The results of this study are consistent with thermal treatment studies that indicate that the primary candidates for the release of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70037124','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70037124"><span id="translatedtitle">A simplified In Situ cosmogenic <span class="hlt">14</span><span class="hlt">C</span> extraction system</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Pigati, J.S.; Lifton, N.A.; Timothy, Jull A.J.; Quade, Jay</p> <p>2010-01-01</p> <p>We describe the design, construction, and testing of a new, simplified in situ radiocarbon extraction system at the University of Arizona. Blank levels for the new system are low ((234 ?? 11) ?? 103 atoms (1 ??; n = 7)) and stable. The precision of a given measurement depends on the concentration of <span class="hlt">14</span><span class="hlt">C</span>, but is typically <5% for concentrations of 100 ?? 103 atoms g-1 or more. The new system is relatively small and easy to construct, costs significantly less than the original in situ <span class="hlt">14</span><span class="hlt">C</span> extraction system at Arizona, and lends itself to future automation. ?? 2010 by the Arizona Board of Regents on behalf of the University of Arizona.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPhCS.675b2004K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPhCS.675b2004K"><span id="translatedtitle">Search for exotic cluster configurations in <span class="hlt">14</span><span class="hlt">C</span> nucleus</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Korotkova, L. Yu; Chernyshev, B. A.; Gurov, Yu B.; Karpuhin, V. S.; Lapushkin, S. V.; Pritula, R. V.; Schurenkova, T. D.</p> <p>2016-02-01</p> <p>The analysis of 2-dimentional Dalitz’ diagram, measured in <span class="hlt">14</span><span class="hlt">C</span>(π-, pd)X reaction, allowed to distinguish the pion absorption by p intranuclear cluster and to obtain an indication on the existence of 3p + 11Li configuration in <span class="hlt">14</span><span class="hlt">C</span> nucleus. Highly excited states of 12,13Be isotopes were found with the energy of Ex ≈ 30 MeV for the first time. It was shown that these states decay as follows 12Be*→p + 11Li and 13Be*→d + 11Li.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5159662','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5159662"><span id="translatedtitle">Convenient preparative synthesis of ( sup <span class="hlt">14</span> <span class="hlt">C</span>)trehalose from ( sup <span class="hlt">14</span> <span class="hlt">C</span>)glucose by intact Escherichia coli cells</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Brand, B.; Boos, W. )</p> <p>1989-09-01</p> <p>At high osmolarity, Escherichia coli synthesizes trehalose intracellularly, irrespective of the nature of the carbon source. Synthesis proceeds via the transfer of UDP-glucose to glucose 6-phosphate, yielding trehalose 6-phosphate, followed by its dephosphorylation to trehalose. This reaction was exploited to preparatively synthesize ({sup <span class="hlt">14</span>}<span class="hlt">C</span>)trehalose from exogenous ({sup <span class="hlt">14</span>}<span class="hlt">C</span>)glucose by using intact bacteria of a mutant (DF214) that could not metabolize glucose. The total yield of radiochemically pure trehalose from glucose was routinely more than 50%.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21036066','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21036066"><span id="translatedtitle">Applications of AMS {sup <span class="hlt">14</span>}<span class="hlt">C</span> on Climate and Archaeology</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gomes, P. R. S.</p> <p>2007-10-26</p> <p>We describe the Accelerator Mass Spectrometry (AMS) technique and two distinct applications of its use with {sup <span class="hlt">14</span>}<span class="hlt">C</span> to study environmental problems in Brazil, such as forest fires and climate changes in the Amazon region and archaeological studies on the early settlements in the Southeast Brazilian coast.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5818632','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5818632"><span id="translatedtitle">Excretion of radioactivity following the intraperitoneal administration of /sup <span class="hlt">14</span>/<span class="hlt">C</span>-DDT, /sup <span class="hlt">14</span>/<span class="hlt">C</span>-DDD, /sup <span class="hlt">14</span>/<span class="hlt">C</span>-DDE and /sup <span class="hlt">14</span>/<span class="hlt">C</span>-DDMU to the rat and Japanese Quail</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Fawcett, S.C.; Bunyan, P.J.; Huson, L.W.; King, L.J.; Stanley, P.I.</p> <p>1981-09-01</p> <p>A study in progress to examine the metabolic fate of DDT in birds and mammals is discussed. The first phase of the study, which is reported in this article, has been to establish the rate of excretion of ratioactivity following the intraperitoneal administrations of /sup <span class="hlt">14</span>/<span class="hlt">C</span>-DDT, /sup <span class="hlt">14</span>/<span class="hlt">C</span>-DDE, /sup <span class="hlt">14</span>/<span class="hlt">C</span>-DDD, and /sup <span class="hlt">14</span>/<span class="hlt">C</span>-DDMU to male rats and male Japanese quail. The mean values from the three animals in each experimental group for the amount of radioactivity excreted daily are given, and it was found that the rats excreted the radioactivity administered as DDT, DDD, and DDE substantially faster than did the quail. DDMU was excreted relatively rapidly and at similar rates. This finding suggests that apparent differences in the rates of excretion of DDT by birds and mammals probably arise from differences in the conversion of DDT to DDD or DDE or in the degradation of these metabolites to DDMU. The Japanese quail differ from the rats in excreting substantial amounts of unchanged DDT, DDE, and DDD, which probably reflects the inability of the Japanese quail to readily metabolise these compounds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70037122','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70037122"><span id="translatedtitle">Extraction of in situ cosmogenic <span class="hlt">14</span><span class="hlt">C</span> from olivine</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Pigati, J.S.; Lifton, N.A.; Timothy, Jull A.J.; Quade, Jay</p> <p>2010-01-01</p> <p>Chemical pretreatment and extraction techniques have been developed previously to extract in situ cosmogenic radiocarbon (in situ <span class="hlt">14</span><span class="hlt">C</span>) from quartz and carbonate. These minerals can be found in most environments on Earth, but are usually absent from mafic terrains. To fill this gap, we conducted numerous experiments aimed at extracting in situ <span class="hlt">14</span><span class="hlt">C</span> from olivine ((Fe,Mg)2SiO4). We were able to extract a stable and reproducible in situ <span class="hlt">14</span><span class="hlt">C</span> component from olivine using stepped heating and a lithium metaborate (LiBO2) flux, following treatment with dilute HNO3 over a variety of experimental conditions. However, measured concentrations for samples from the Tabernacle Hill basalt flow (17.3 ?? 0.3 ka4) in central Utah and the McCarty's basalt flow (3.0 ?? 0.2 ka) in western New Mexico were significantly lower than expected based on exposure of olivine in our samples to cosmic rays at each site. The source of the discrepancy is not clear. We speculate that in situ <span class="hlt">14</span><span class="hlt">C</span> atoms may not have been released from Mg-rich crystal lattices (the olivine composition at both sites was ~Fo65Fa35). Alternatively, a portion of the <span class="hlt">14</span><span class="hlt">C</span> atoms released from the olivine grains may have become trapped in synthetic spinel-like minerals that were created in the olivine-flux mixture during the extraction process, or were simply retained in the mixture itself. Regardless, the magnitude of the discrepancy appears to be inversely proportional to the Fe/(Fe+Mg) ratio of the olivine separates. If we apply a simple correction factor based on the chemical composition of the separates, then corrected in situ <span class="hlt">14</span><span class="hlt">C</span> concentrations are similar to theoretical values at both sites. At this time, we do not know if this agreement is fortuitous or real. Future research should include measurement of in situ <span class="hlt">14</span><span class="hlt">C</span> concentrations in olivine from known-age basalt flows with different chemical compositions (i.e. more Fe-rich) to determine if this correction is robust for all olivine-bearing rocks. ?? 2010 by the Arizona</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/15013585','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/15013585"><span id="translatedtitle">Reconstructing Ocean Circulation using Coral (triangle)<span class="hlt">14</span><span class="hlt">C</span> Time Series</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kashgarian, M; Guilderson, T P</p> <p>2001-02-23</p> <p>We utilize monthly {sup <span class="hlt">14</span>}<span class="hlt">C</span> data derived from coral archives in conjunction with ocean circulation models to address two questions: (1) how does the shallow circulation of the tropical Pacific vary on seasonal to decadal time scales and (2) which dynamic processes determine the mean vertical structure of the equatorial Pacific thermocline. Our results directly impact the understanding of global climate events such as the El Nino-Southern Oscillation (ENSO). To study changes in ocean circulation and water mass distribution involved in the genesis and evolution of ENSO and decadal climate variability, it is necessary to have records of climate variables several decades in length. Continuous instrumental records are limited because technology for continuous monitoring of ocean currents (e.g. satellites and moored arrays) has only recently been available, and ships of opportunity archives such as COADS contain large spatial and temporal biases. In addition, temperature and salinity in surface waters are not conservative and thus can not be independently relied upon to trace water masses, reducing the utility of historical observations. Radiocarbon in sea water is a quasi-conservative water mass tracer and is incorporated into coral skeletal material, thus coral {sup <span class="hlt">14</span>}<span class="hlt">C</span> records can be used to reconstruct changes in shallow circulation that would be difficult to characterize using instrumental data. High resolution {Delta}{sup <span class="hlt">14</span>}<span class="hlt">C</span> timeseries such as ours, provide a powerful constraint on the rate of surface ocean mixing and hold great promise to augment one time oceanographic surveys. {Delta}{sup <span class="hlt">14</span>}<span class="hlt">C</span> timeseries such as these, not only provide fundamental information about the shallow circulation of the Pacific, but can also be directly used as a benchmark for the next generation of high resolution ocean models used in prognosticating climate. The measurement of {Delta}{sup <span class="hlt">14</span>}<span class="hlt">C</span> in biological archives such as tree rings and coral growth bands is a direct record of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=396256','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=396256"><span id="translatedtitle">Movement and Metabolism of Kinetin-<span class="hlt">14</span><span class="hlt">C</span> and of Adenine-<span class="hlt">14</span><span class="hlt">C</span> in Coleus Petiole Segments of Increasing Age 1</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Veen, Henk; Jacobs, William P.</p> <p>1969-01-01</p> <p>To see if polar movement was typical of growth-regulators other than auxins, the movement of adenine-8-<span class="hlt">14</span><span class="hlt">C</span> and of kinetin-8-<span class="hlt">14</span><span class="hlt">C</span> was studied in segments cut from petioles of increasing age. No polarity was found. In time-course experiments lasting 24 hr, kinetin showed a progressive increase of radioactivity in receiver blocks, while adenine showed a maximum at 8 hr with a decline thereafter. More kinetin moved through older segments than through younger ones. There was no difference in net loss as far as the position of the donor block is concerned. However, the loss of radioactivity from adenine donor blocks was much higher than the loss of radioactivity from kinetin donor blocks. The radioactivity in receiver blocks after 24 hr treatment with kinetin-<span class="hlt">14</span><span class="hlt">C</span> was still with kinetin, judging by location on chromatograms. By the same criterion, adenine and a smaller amount of some other compound were in receiver blocks after a 6 hr transport with adenine-<span class="hlt">14</span><span class="hlt">C</span> in the donors. By contrast, more zones of radioactivity were extracted from petiole segments to which kinetin or adenine had been added. For both purine derivatives the original compound represented no more than 20% of the total radioactivity extracted from the tissue after a transport period of 24 hr. PMID:16657203</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6967766','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6967766"><span id="translatedtitle">Examination of surface exposure age of Antarctic moraines using in situ produced [sup 10]Be and [sup <span class="hlt">26</span>]<span class="hlt">Al</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Brown, E.T.; Edmond, J.M. ); Raisbeck, G.M.; Yiou, F. ); Kurz, M.D.; Brook, E.J. )</p> <p>1991-08-01</p> <p>Concentrations of [sup 10]Be (t[sub 1/2] = 1.5 [times] 10[sup 6]y) and [sup <span class="hlt">26</span>]<span class="hlt">Al</span> (t[sub 1/2] = 0.72 [times] 10[sup 6]y) have been determined by accelerator mass spectrometry (AMS) in a suite of quartz samples taken from sandstone boulders in several moraines in Arena Valley, a dry valley adjacent to the Taylor Glacier in the Quatermain Mountains, Southern Victoria Land, East Antarctica. These isotopes are produced in surficial quartz by cosmic ray spallation of O and Si. The concentrations in these samples ranged from 6.1 [times] 10[sup 5] to 3.0 [times] 10[sup 7] at g[sup [minus]1] for [sup 10]Be and from 9.4 [times] 10[sup 6] to 1.2 [times] 10[sup 8] at g[sup [minus]1] for [sup <span class="hlt">26</span>]<span class="hlt">Al</span>, depending upon the extent of exposure at the surface. Production rates of 17[sub [minus]4][sup +16] at g[sup [minus]1]y[sup [minus]1] for [sup 10]Be and 113[sub [minus]16][sup +54] at g[sup [minus]1]y[sup [minus]1] for [sup <span class="hlt">26</span>]<span class="hlt">Al</span> at 1300 m and 87[degree]S and a [sup <span class="hlt">26</span>]<span class="hlt">Al</span>:[sup 10]Be production ratio of 6.5[sub [minus]1.3][sup +1.3] were calculated from the data. These values correspond to sea-level production rates at high geomagnetic latitude of 6.4 at g[sup [minus]1]y[sup [minus]1] and 41.7 at g[sup [minus]1]y[sup [minus]1] for [sup 10]Be and [sup <span class="hlt">26</span>]<span class="hlt">Al</span>, respectively, consistent with determinations based on [approximately]11 Ky glacially polished surfaces in the Sierra Nevada in California. These production rates imply exposure ages for the various moraines ranging from 50 Ky to 2.5 My, in accordance with other geological evidence. The [sup 10]Be and [sup <span class="hlt">26</span>]<span class="hlt">Al</span> ages of these rocks compare favorably with those found using a similar dating method based on in situ production of [sup 3]He.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012LPI....43.2255K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012LPI....43.2255K"><span id="translatedtitle">Heterogeneous Distribution of ^2^6Al at the Birth of the Solar System: Evidence from Corundum-Bearing Refractory Inclusions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Krot, A. N.; Makide, K.; Nagashima, K.; Huss, G. R.; Hellebrand, E.; Petaev, M. I.</p> <p>2012-03-01</p> <p>Corundum-bearing CAIs recorded heterogeneous distribution of ^2^6Al at the birth of the solar system. We suggest that ^2^6Al was injected into the protosolar molecular cloud core by a wind from a massive star and was later homogenized through the disk.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6551412','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6551412"><span id="translatedtitle">Degradation of /sup <span class="hlt">14</span>/<span class="hlt">C</span>-labeled lignins and /sup <span class="hlt">14</span>/<span class="hlt">C</span>-labeled aromatic acids by fusarium solani</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Norris, D.M.</p> <p>1980-08-01</p> <p>Abilities of isolate AF-W1 of Fusarium solani to degrade the side chain and the ring structure of synthetic dehydrogenative polymerizates, aromatic acids, or lignin in sound wood were investigated under several conditions of growth substrate or basal medium and pH. Significant transformations of lignins occurred in 50 days in both unextracted and extracted sound wood substrances with 3% malt as the growth substrate and the pH buffered initially at 4.0 with 2,2-dimethylsuccinate. Degradation of lignin in such woods also occurred under unbuffered pH conditions when a basal medium of either 3% malt or powdered cellulose in deionized water was present. Decomposition of the lignin in these woods did not occur in cultures where D-glucose was present as a growth substrate. F. solani significantly transformed, as measured as evolved /sup 14/CO/sub 2/, both synthetic side chain (beta, gamma)-/sup <span class="hlt">14</span>/<span class="hlt">C</span>- and U-ring-/sup <span class="hlt">14</span>/<span class="hlt">C</span>-labeled lignins in 30 days under liquid culture conditions of only distilled deionized water and no pH adjustment. Degradation of dehydrogenative polymerizates by F. solani was reduced drastically when D2 was the liquid medium. AF-W1 also cleaved the alpha-/sup <span class="hlt">14</span>/<span class="hlt">C</span> from p- hydroxybenzoic acid and evolved /sup 14/CO/sub 2/ from the substrace, (3-/sup <span class="hlt">14</span>/<span class="hlt">C</span>) cinnamic acid. Thus, the fungus cleaved side chain carbon from substrate that originally lacked hydroxyl substitution on the aromatic nucleus. Surprisingly, small amounts of /sup <span class="hlt">14</span>/<span class="hlt">C</span> cleaved from aromatic acids by F. solani were incorporated into cell mass. Initial buffering of the culture medium to pH 4.0 or 5.0 with 0.1 M2,2-dimethylsuccinate significantly increased F. solani degradation of all lignins or aromatic acids. Results indicated that AF-W1 used lignin as a sole carbon source.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1814159T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1814159T"><span id="translatedtitle">Toward determining the uncertainties associated with the seismic histories retrieved from in situ <span class="hlt">36</span><span class="hlt">Cl</span> cosmogenic nuclide fault scarp dating: model reappraisal.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tesson, Jim; Benedetti, Lucilla</p> <p>2016-04-01</p> <p>How the past seismic activity of faults has varied over the last 20 ky is a crucial information for seismic hazard assessment and for the understanding of fault-interaction processes. Chlorine 36 in situ produced cosmogenic nuclide is increasingly used to retrieve past earthquakes histories on seismically exhumed limestone normal fault-scarps. Schlagenhauf et al. in 2010 developed a modeling code with a forward approach enabling the test of scenarii generated with a priori constraints (number of events, age and slip of events and pre-exposure time). The main shortcomings of this forward approach were the limited number of testable scenarii and the difficulty to derive the associated uncertainties. We present here a reappraisal methodology with an inverse approach using an optimization algorithm. This modelling approach enables 1-exploring the parameter space (age and slip of events), 2-finding the best scenario without a priori constraints and 3-precisely quantifying the associated uncertainties by determining the range of plausible models. Through a series of synthetic tests, we observed that the algorithm revealed a great capacity to constrain event slips and ages in a short computational time (several hours) with an accuracy that can reach 0.1 ky and 0.5 m for the age and slip of exhumation event, respectively. We also explore the influence of the pre-exposure history (amount of <span class="hlt">36</span><span class="hlt">Cl</span> accumulated when the sampled fault-plane was still buried under the colluvial wedge) and show that it has an important impact on the generated scenarii. This new modeling also allows now to accurately determining this parameter. Finally, the results show that any given [<span class="hlt">36</span><span class="hlt">Cl</span>] profile results in a unique exhumation solution. We then apply this new model to the Magnola fault (Italy) dataset (Schlgenhauf et al. 2011). In agreement the previously published results, our model also results in 3 intense periods of seismic activity. However, the contribution of the pre-exposure history is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70030141','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70030141"><span id="translatedtitle">Cosmogenic 10Be and <span class="hlt">36</span><span class="hlt">Cl</span> geochronology of offset alluvial fans along the northern Death Valley fault zone: Implications for transient strain in the eastern California shear zone</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Frankel, K.L.; Brantley, K.S.; Dolan, J.F.; Finkel, R.C.; Klinger, R.E.; Knott, J.R.; Machette, M.N.; Owen, L.A.; Phillips, F.M.; Slate, J.L.; Wernicke, B.P.</p> <p>2007-01-01</p> <p>The northern Death Valley fault zone (NDVFZ) has long been recognized as a major right-lateral strike-slip fault in the eastern California shear zone (ECSZ). However, its geologic slip rate has been difficult to determine. Using high-resolution digital topographic imagery and terrestrial cosmogenic nuclide dating, we present the first geochronologically determined slip rate for the NDVFZ. Our study focuses on the Red Wall Canyon alluvial fan, which exposes clean dextral offsets of seven channels. Analysis of airborne laser swath mapping data indicates ???297 ?? 9 m of right-lateral displacement on the fault system since the late Pleistocene. In situ terrestrial cosmogenic 10Be and 36C1 geochronology was used to date the Red Wall Canyon fan and a second, correlative fan also cut by the fault. Beryllium 10 dates from large cobbles and boulders provide a maximum age of 70 +22/-20 ka for the offset landforms. The minimum age of the alluvial fan deposits based on <span class="hlt">36</span><span class="hlt">Cl</span> depth profiles is 63 ?? 8 ka. Combining the offset measurement with the cosmogenic 10Be date yields a geologic fault slip rate of 4.2 +1.9/-1.1 mm yr-1, whereas the <span class="hlt">36</span><span class="hlt">Cl</span> data indicate 4.7 +0.9/-0.6 mm yr-1 of slip. Summing these slip rates with known rates on the Owens Valley, Hunter Mountain, and Stateline faults at similar latitudes suggests a total geologic slip rate across the northern ECSZ of ???8.5 to 10 mm yr-1. This rate is commensurate with the overall geodetic rate and implies that the apparent discrepancy between geologic and geodetic data observed in the Mojave section of the ECSZ does not extend north of the Garlock fault. Although the overall geodetic rates are similar, the best estimates based on geology predict higher strain rates in the eastern part of the ECSZ than to the west, whereas the observed geodetic strain is relatively constant. Copyright 2007 by the American Geophysical Union.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.T43D..05S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.T43D..05S"><span id="translatedtitle">Three time scales of earthquake clustering inferred from in-situ <span class="hlt">36</span><span class="hlt">Cl</span> cosmogenic dating on the Velino-Magnola fault (Central Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schlagenhauf, A.; Manighetti, I.; Benedetti, L.; Gaudemer, Y.; Malavieille, J.; Finkel, R. C.; Pou, K.</p> <p>2010-12-01</p> <p>Using in-situ <span class="hlt">36</span><span class="hlt">Cl</span> cosmogenic exposure dating, we determine the earthquake slip release pattern over the last ~ 14 kyrs along one of the major active normal fault systems in Central Italy. The ~ 40 km-long Velino-Magnola fault (VMF) is located ~ 20 km SW from the epicenter of the devastating April 2009 l’Aquila earthquake. We sampled the VMF at five well-separated sites along its length, and modeled the <span class="hlt">36</span><span class="hlt">Cl</span> concentrations measured in the 400 samples (Schlagenhauf et al. 2010). We find that the fault has broken in large earthquakes which clustered at three different time scales -monthly, centennial and millennial. More precisely, the fault sustained phases of intense seismic activity, separated by ~ 3 kyr-long periods of relative quiescence. The phases of strong activity lasted 3-4 kyrs (millennial scale) and included 3-4 ‘rupture events’ that repeated every 0.5-1 kyr (centennial scale). Each of these ‘rupture events’ was likely a sequence of a few large earthquakes cascading in a very short time, a few months at most (monthly scale), to eventually break the entire VMF. Each earthquake apparently broke a section of the fault of 10-20 km and produced maximum surface displacements of 2-3.5 meters. The fault seems to enter a phase of intense activity when the accumulated strain reaches a specific threshold. Based on this observation, the Velino-Magnola fault seems presently in a stage of relative quiescence. Yet, it may soon re-enter a phase of paroxysmal seismic activity. If its forthcoming earthquakes are similar to those we have documented, several may occur in cascade over a short time, each with a magnitude up to 6.5-6.9. Seismic hazard is thus high in the Lazio-Abruzzo region, especially in the Fucino area. References: Schlagenhauf A., Y. Gaudemer, L. Benedetti, I. Manighetti, L. Palumbo, I. Schimmelpfennig, R. Finkel, and K. Pou (2010). Using in-situ Chlorine-36 cosmonuclide to recover past earthquake histories on limestone normal fault scarps: A</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..1815392T&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..1815392T&link_type=ABSTRACT"><span id="translatedtitle">Slip rate variability over the Holocene period in the middle Aterno fault system (Italy), retrieved from in situ <span class="hlt">36</span><span class="hlt">Cl</span> cosmogenic nuclide dating of exhumed fault-plane.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tesson, Jim; Benedetti, Lucilla; Pucci, Stefano; Villani, Fabio; Bourles, Didier; Keddadouche, Karim; Aumaitre, Georges</p> <p>2016-04-01</p> <p>Numerous numerical modeling studies have described and quantified non-stochastic spatio-temporal variations of earthquake occurrences within fault-networks, such as temporal clustered earthquakes or fault synchronization. However, very few long-enough paleoseismological and geological records are available to test those models against well-constrained dataset and thus account for such variability in the fault behavior. The prerequisites for improving our understanding of fault-rupture processes and thus our capacity to better assess seismic hazard are to acquire paleoseismological records that enable to derive both long-term slip-rate and short-term variability, on a large population of faults and/or within a fault system. These conditions met in Central Apennines, an extensional province where substantial paleoseismological dataset accurately described the Holocene seismic history of a dense network of normal faults. In this study we use <span class="hlt">36</span><span class="hlt">Cl</span> in situ cosmogenic nuclide to retrieve the seismic history of 3 faults belonging to the Middle Aterno fault system, from north to south: the Bazzano fault, the Roccapreturo fault and the Sulmona fault, a portion of which ruptured during the 2009 L'Aquila earthquake in Italy. We use a new modeling approach to determine the age and slip of past seismic events from the <span class="hlt">36</span><span class="hlt">Cl</span> concentration profiles. This model is based on an inverse approach and uses an optimization algorithm enabling all the parameter space (number of events, age and slip of events, pre-exposure) to be explored without a priori constraints (see Tesson et al. in session TS4.2/NH4.16/SM3.8). Using this new approach, we precisely determine the slip events occurrences over the Holocene period of those three faults. The results indicate that the three studied faults have ruptured between 4.5 and 5.5 ka, while the southernmost part of the system has also ruptured between at 1.5-3 ka (Sulmona fault and southern segment of Roccapreturo). Those results are in agreement</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19896253','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19896253"><span id="translatedtitle">Migration of (<span class="hlt">14</span>)<span class="hlt">C</span> in the paddy soil-to-rice plant system after (<span class="hlt">14</span>)<span class="hlt">C</span>-acetic acid breakdown by microorganisms below the plow layer.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ogiyama, Shinichi; Takeda, Hiroshi; Ishii, Nobuyoshi; Uchida, Shigeo</p> <p>2010-02-01</p> <p>Migration of (<span class="hlt">14</span>)<span class="hlt">C</span> derived from (<span class="hlt">14</span>)<span class="hlt">C</span>-acetic acid was examined by using soils sampled from paddies in four administrative areas in Japan (Aomori, Yamanashi, Ehime and Okinawa) and rice plant in a tracer experiment to understand the fate of (<span class="hlt">14</span>)<span class="hlt">C</span> in the paddy soil-to-rice plant system. The loss of (<span class="hlt">14</span>)<span class="hlt">C</span> radioactivity levels derived from (<span class="hlt">14</span>)<span class="hlt">C</span>-acetic acid was caused by soil microorganism breakdown. A part of the (<span class="hlt">14</span>)<span class="hlt">C</span> fixation to soil was caused by microbial assimilation into the fatty acid fraction. (<span class="hlt">14</span>)<span class="hlt">C</span> moved upward via two different types of (<span class="hlt">14</span>)<span class="hlt">C</span> dynamics in soil: quick movement upward; and constant but slow movement upward. (<span class="hlt">14</span>)<span class="hlt">C</span> was highly assimilated into the plant panicle and that was caused by the root-uptake and the transfer of (<span class="hlt">14</span>)<span class="hlt">C</span>. Migration of (<span class="hlt">14</span>)<span class="hlt">C</span> derived from (<span class="hlt">14</span>)<span class="hlt">C</span>-acetic acid relied heavily upon changes of chemical forms and characteristics of (<span class="hlt">14</span>)<span class="hlt">C</span>-compound as caused by microorganisms in soil.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1429493','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1429493"><span id="translatedtitle">The metabolism of [<span class="hlt">14</span><span class="hlt">C</span>]-debrisoquine in man.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Idle, J R; Mahgoub, A; Angelo, M M; Dring, L G; Lancaster, R; Smith, R L</p> <p>1979-01-01</p> <p>1 The synthesis of [<span class="hlt">14</span><span class="hlt">C</span>]-debrisoquine hydrochloride and 4-hydroxy-debrisoquine sulphate is described. 2 The metabolic fate and excretion profile in both urine and faeces of <span class="hlt">14</span><span class="hlt">C</span>-labelled debrisoquine was studied in five healthy human subjects. 3 Investigations showed that the drug is well-absorbed after a single oral dose of 32 mg and quantitatively eliminated from the body within three days. 4 4-Hydroxy-debrisoquine is the major metabolite of debrisoquine, although significant amounts of 5-,6-, 7- and 8-hydroxy-debrisoquine are also formed. 5 Electron-capture gas chromatography is a useful method for measuring debrisoquine and its five hydroxylated metabolites in urine at the pg level. PMID:371651</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26095095','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26095095"><span id="translatedtitle">Pediatric microdose and microtracer studies using <span class="hlt">14</span><span class="hlt">C</span> in Europe.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Turner, M A; Mooij, M G; Vaes, W H J; Windhorst, A D; Hendrikse, N H; Knibbe, C A J; Kõrgvee, L T; Maruszak, W; Grynkiewicz, G; Garner, R C; Tibboel, D; Park, B K; de Wildt, S N</p> <p>2015-09-01</p> <p>Important information gaps remain on the efficacy and safety of drugs in children. Pediatric drug development encounters several ethical, practical, and scientific challenges. One barrier to the evaluation of medicines for children is a lack of innovative methodologies that have been adapted to the needs of children. This article presents our successful experience of pediatric microdose and microtracer studies using (<span class="hlt">14</span>) <span class="hlt">C</span>-labeled probes in Europe to illustrate the strengths and limitations of these approaches.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013NIMPB.294..662F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013NIMPB.294..662F"><span id="translatedtitle">May <span class="hlt">14</span><span class="hlt">C</span> be used to date contemporary art?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fedi, M. E.; Caforio, L.; Mandò, P. A.; Petrucci, F.; Taccetti, F.</p> <p>2013-01-01</p> <p>The use of radiocarbon in forensics is by now widespread, thanks to the so-called bomb peak, which makes it possible to perform high-precision dating. Since 1955, <span class="hlt">14</span><span class="hlt">C</span> concentration in the atmosphere had strongly increased due to nuclear explosions, reaching its maximum value in 1963-1965. After the Nuclear Test Ban Treaty, <span class="hlt">14</span><span class="hlt">C</span> started to decrease as a consequence of the exchanges between atmosphere and the other natural carbon reservoirs. Nowadays, it is still slightly above the pre-bomb value. The work presented in this paper is based on the idea of exploiting the bomb peak to “precisely” date works of contemporary art, with the aim at identifying possible fakes. We analysed two kinds of materials from the 20th century: newspapers and painting canvases. Newspaper samples were taken because they might in principle be considered to represent dated samples (considering the date on the issues). Our data (28 samples) show a trend similar to atmospheric data in the literature, although with some differences; the paper peak is flatter and shifted towards more recent years (about five years) with respect to the atmospheric data. This can be explained by taking paper manufacturing processes into account. As to the canvas samples, the measured <span class="hlt">14</span><span class="hlt">C</span> concentrations were generally reasonably consistent with the expected concentrations (based on the year on the paintings). However, this does not indicate that the interpretation of the results is simpler and more straightforward. Obviously, we only measure the <span class="hlt">14</span><span class="hlt">C</span> concentration of the fibre used for the canvas, which does not necessarily measure the date the painting was manufactured. In this paper, sample preparation and experimental results will be discussed, in order to show the potential as well as the limitations of radiocarbon to date contemporary art.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhRvC..92b4624O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhRvC..92b4624O"><span id="translatedtitle">Airy structure in 16O+<span class="hlt">14</span><span class="hlt">C</span> nuclear rainbow scattering</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ohkubo, S.; Hirabayashi, Y.</p> <p>2015-08-01</p> <p>The Airy structure in 16 O +<span class="hlt">14</span> <span class="hlt">C</span> rainbow scattering is studied with an extended double-folding (EDF) model that describes all the diagonal and off-diagonal coupling potentials derived from the microscopic realistic wave functions for 16 O by using a density-dependent nucleon-nucleon force. The experimental angular distributions at EL=132 , 281, and 382.2 MeV are well reproduced by the calculations. By studying the energy evolution of the Airy structure, the Airy minimum around θ =76∘ in the angular distribution at EL=132 MeV is assigned as the second-order Airy minimum A 2 in contrast to the recent literature which assigns it as the third order A 3 . The Airy minima in the 90∘ excitation function is investigated in comparison with well-known 16 O +16 O and 12 C +12 C systems. Evolution of the Airy structure into the molecular resonances with the 16 O +<span class="hlt">14</span> <span class="hlt">C</span> cluster structure in the low-energy region around Ec .m .=30 MeV is discussed. It is predicted theoretically for the first time for a non-4 N 16O +<span class="hlt">14</span> <span class="hlt">C</span> system that Airy elephants in the 90∘ excitation function are present.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998GeoRL..25.1321M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998GeoRL..25.1321M"><span id="translatedtitle">Temporal variation in the interhemispheric <span class="hlt">14</span><span class="hlt">C</span> offset</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McCormac, F. G.; Hogg, A. G.; Higham, T. F. G.; Lynch-Stieglitz, J.; Broecker, W. S.; Baillie, M. G. L.; Palmer, J.; Xiong, L.; Pilcher, J. R.; Brown, D.; Hoper, S. T.</p> <p></p> <p>Contemporaneous tree-ring dated wood, from trees in the northern and southern hemispheres, gives different <span class="hlt">14</span><span class="hlt">C</span> dates. Previous studies [Vogel et al., 1986; 1993] using wood from South Africa and The Netherlands have shown depletion's of -4.56 ± 0.85‰ and -5.12±0.62‰ respectively. This translates to age differences of 36±7 and 41±5 years (yrs) with the southern hemisphere giving the older dates. More recently, Stuiver and Braziunas [1998] have shown that an offset of 23±4 yrs exists between combined 19th century wood measurements from Tasmania and Chile in the southern hemisphere and the west coast of the U.S. (Washington) in the northern hemisphere. In this study measurements on contemporaneous decadal samples of oak from the British Isles and cedar from New Zealand over the period 1725 to 1885 AD show a depletion of -3.4±0.58‰ (27.2±4.7 yrs). However, data after 1895 AD has a mean offset of 0.66±1.06‰ (-5.3±8.5 yrs) with increased variance compared to 19th century data. This, we believe, is attributable to anthropogenic fossil fuel, which, due to its long residence time in the earth, has long since lost any <span class="hlt">14</span><span class="hlt">C</span> component and when burned preferentially depletes the northern hemisphere atmosphere of <span class="hlt">14</span><span class="hlt">C</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NIMPB.371..365G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NIMPB.371..365G"><span id="translatedtitle"><span class="hlt">14</span><span class="hlt">C</span> content in aerosols in Mexico City</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gómez, V.; Solís, C.; Chávez, E.; Andrade, E.; Ortiz, M. E.; Huerta, A.; Aragón, J.; Rodríguez-Ceja, M.; Martínez, M. A.; Ortiz, E.</p> <p>2016-03-01</p> <p><span class="hlt">14</span><span class="hlt">C</span>-AMS of total carbon was determined in aerosols (PM10 fraction), collected in Mexico City during two weeks from 21 November to 3 December 2012. Other tracers such as total carbon (TC), organic carbon (OC), elemental carbon (EC) and trace element contents were also determined. F<span class="hlt">14</span><span class="hlt">C</span> values varied from 0.39 to 0.48 with an average of 0.43. These values are slightly lower than those previously obtained for PM2.5 in 2003 and 2006 and reflect a high contribution of fossil CO2 to the carbonaceous matter in aerosols from Mexico City. In contrast, from 2006 to 2012 PM10 increased; EC, Ca, Ti and Fe concentrations remained constant, while OC, TC and K concentrations decreased. The use of potassium as an indicator of biomass burning showed that this source was negligible during this campaign. Combined analytical approaches allowed us to distinguish temporal variations of anthropogenic and natural inputs to the F<span class="hlt">14</span><span class="hlt">C</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5491023','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5491023"><span id="translatedtitle">Disposition of (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)dimercaptosuccinic acid in mice</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Liang, Y.Y.; Marlowe, C.; Waddell, W.J.</p> <p>1986-04-01</p> <p>Dimercaptosuccinic acid labeled with /sup <span class="hlt">14</span>/<span class="hlt">C</span> ((/sup <span class="hlt">14</span>/<span class="hlt">C</span>)DMSA) was administered to mice iv; the mice were frozen by immersion in dry ice/hexane at 6 and 20 min and 1, 3, 9, and 24 hr after injection. The frozen mice were sectioned and processed for whole-body autoradiography for soluble substances. The radioactivity was highly localized in extracellular fluids such as the subcutaneous, intrapleural, intraperitoneal, and periosteal spaces. There was a pronounced accumulation in the periosteal fluid above that in other fluids during the first hour after injection. Most of the radioactivity was eliminated by the kidney and liver. Pretreatment of a mouse with HgCl/sub 2/ subcutaneously 1 hr before (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)DMSA produced an increase in radioactivity in the liver and a decrease in the lungs. A high concentration of radioactivity was seen at the subcutaneous site of injection of the HgCl/sub 2/. The results are interpreted to indicate that most of the DMSA is in the extracellular space but that it can cross cellular membranes to some extent. The pronounced accumulation in periosteal fluid may be an interaction of DMSA with Ca2+ in this space. No tissue had a pronounced retention of the compound, but the lungs retained more than most other tissues.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21199603','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21199603"><span id="translatedtitle">Lowest l=0 proton resonance in {sup 26}Si and implications for nucleosynthesis of {sup <span class="hlt">26</span>}<span class="hlt">Al</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Peplowski, P. N.; Baby, L. T.; Wiedenhoever, I.; Diffenderfer, E.; Hoeflich, P.; Rojas, A.; Volya, A.; Dekat, S. E.; Gay, D. L.; Grubor-Urosevic, O.; Kaye, R. A.; Keeley, N.</p> <p>2009-03-15</p> <p>Using a beam of the radioactive isotope {sup 25}Al, produced with the new RESOLUT facility, we measured the direct (d,n) proton-transfer reaction leading to low-lying proton resonances in {sup 26}Si. We observed the lowest l=0 proton resonance, identified with the 3{sup +} state at 5.914-MeV excitation energy. This result eliminates the largest uncertainty in astrophysical reaction rates involved in the nucleosynthesis of {sup <span class="hlt">26</span>}<span class="hlt">Al</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26274415','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26274415"><span id="translatedtitle">Measurement of 23Na(α,p)26Mg at Energies Relevant to <span class="hlt">26</span><span class="hlt">Al</span> Production in Massive Stars.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tomlinson, J R; Fallis, J; Laird, A M; Fox, S P; Akers, C; Alcorta, M; Bentley, M A; Christian, G; Davids, B; Davinson, T; Fulton, B R; Galinski, N; Rojas, A; Ruiz, C; de Séréville, N; Shen, M; Shotter, A C</p> <p>2015-07-31</p> <p><span class="hlt">26</span><span class="hlt">Al</span> is an important radioisotope in astrophysics that provides evidence of ongoing nucleosynthesis in the Galaxy. The 23Na(α, p)26Mg reaction has been identified by a sensitivity study as being one of the most important reactions for the production of <span class="hlt">26</span><span class="hlt">Al</span> in the convective C/Ne burning shell of massive stars. Owing to large uncertainties in previous experimental data, model calculations are used for the reaction rate of 23Na(α, p)26Mg in this sensitivity study. Current experimental data suggest a reaction rate a factor of ∼40 higher than model calculations. However, a new measurement of this reaction cross section has been made in inverse kinematics in the energy range E(c.m.)=1.28-3.15  MeV at TRIUMF, and found to be in reasonable agreement with the model calculation. A new reaction rate is calculated and tight constraints on the uncertainty in the production of <span class="hlt">26</span><span class="hlt">Al</span>, due to this reaction, are determined. PMID:26274415</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26274415','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26274415"><span id="translatedtitle">Measurement of 23Na(α,p)26Mg at Energies Relevant to <span class="hlt">26</span><span class="hlt">Al</span> Production in Massive Stars.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tomlinson, J R; Fallis, J; Laird, A M; Fox, S P; Akers, C; Alcorta, M; Bentley, M A; Christian, G; Davids, B; Davinson, T; Fulton, B R; Galinski, N; Rojas, A; Ruiz, C; de Séréville, N; Shen, M; Shotter, A C</p> <p>2015-07-31</p> <p><span class="hlt">26</span><span class="hlt">Al</span> is an important radioisotope in astrophysics that provides evidence of ongoing nucleosynthesis in the Galaxy. The 23Na(α, p)26Mg reaction has been identified by a sensitivity study as being one of the most important reactions for the production of <span class="hlt">26</span><span class="hlt">Al</span> in the convective C/Ne burning shell of massive stars. Owing to large uncertainties in previous experimental data, model calculations are used for the reaction rate of 23Na(α, p)26Mg in this sensitivity study. Current experimental data suggest a reaction rate a factor of ∼40 higher than model calculations. However, a new measurement of this reaction cross section has been made in inverse kinematics in the energy range E(c.m.)=1.28-3.15  MeV at TRIUMF, and found to be in reasonable agreement with the model calculation. A new reaction rate is calculated and tight constraints on the uncertainty in the production of <span class="hlt">26</span><span class="hlt">Al</span>, due to this reaction, are determined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21448880','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21448880"><span id="translatedtitle">{sup 60}Fe AND {sup <span class="hlt">26</span>}<span class="hlt">Al</span> IN CHONDRULES FROM UNEQUILIBRATED CHONDRITES: IMPLICATIONS FOR EARLY SOLAR SYSTEM PROCESSES</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mishra, R. K.; Goswami, J. N.; Rudraswami, N. G.; Tachibana, S.; Huss, G. R.</p> <p>2010-05-10</p> <p>The presence of about a dozen short-lived nuclides in the early solar system, including {sup 60}Fe and {sup <span class="hlt">26</span>}<span class="hlt">Al</span>, has been established from isotopic studies of meteorite samples. An accurate estimation of solar system initial abundance of {sup 60}Fe, a distinct product of stellar nucleosynthesis, is important to infer the stellar source of this nuclide. Previous studies in this regard suffered from the lack of exact knowledge of the time of formation of the analyzed meteorite samples. We present here results obtained from the first combined study of {sup 60}Fe and {sup <span class="hlt">26</span>}<span class="hlt">Al</span> records in early solar system objects to remove this ambiguity. Chondrules from unequilibrated ordinary chondrites belonging to low petrologic grades were analyzed for their Fe-Ni and Al-Mg isotope systematics. The Al-Mg isotope data provide the time of formation of the analyzed chondrules relative to the first solar system solids, the Ca-Al-rich inclusions. The inferred initial {sup 60}Fe/{sup 56}Fe values of four chondrules, combined with their time of formation based on Al-Mg isotope data, yielded a weighted mean value of (6.3 {+-} 2) x 10{sup -7} for solar system initial {sup 60}Fe/{sup 56}Fe. This argues for a high-mass supernova as the source of {sup 60}Fe along with {sup <span class="hlt">26</span>}<span class="hlt">Al</span> and several other short-lived nuclides present in the early solar system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/452098','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/452098"><span id="translatedtitle">The fate of {sup <span class="hlt">14</span>}<span class="hlt">C</span>-pyrene and {sup <span class="hlt">14</span>}<span class="hlt">C</span>-chrysene in soils amended with a PAH mixture</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Guthrie, E.; Thompkins, J.; Pfaender, F.</p> <p>1995-12-31</p> <p>Polycyclic Aromatic Hydrocarbons (PAH) are ubiquitous environmental contaminants at many hazardous waste sites. Microbial processes are known to influence the fate of PAH in soils and can effect PAH structure, toxicity, bioavailability, and association with soil organic matter (SOM). Experiments were conducted to determine the extent of {sup <span class="hlt">14</span>}<span class="hlt">C</span>-pyrene or {sup <span class="hlt">14</span>}<span class="hlt">C</span>-chrysene associations with soil organic matter (SOM) in soils amended with a PAH mixture and either a [4,5,9,10-{sup <span class="hlt">14</span>}<span class="hlt">C</span>]pyrene or [5,6,11,12-{sup <span class="hlt">14</span>}<span class="hlt">C</span>] chrysene tracer. Changes in microbial respiration ({sup 14}CO{sub 2} efflux), {sup <span class="hlt">14</span>}<span class="hlt">C</span>-volatile organics, {sup <span class="hlt">14</span>}<span class="hlt">C</span>-water soluble metabolites, and {sup <span class="hlt">14</span>}<span class="hlt">C</span>-SOM were measured over time in continuously, aerated microcosms. The bioavailability of {sup <span class="hlt">14</span>}<span class="hlt">C</span>-products in SOM fractions was determined using a mineralization endpoint assay. Extracts of {sup <span class="hlt">14</span>}<span class="hlt">C</span> products in SOM fractions were tested for acute and chronic toxicity using Microtox{trademark}. The {sup <span class="hlt">14</span>}<span class="hlt">C</span>-products associated with residual soil fractions were further extracted with HF/HCI and methylene chloride and then analyzed with LC-MS. The presence of a PAH mixture enhanced {sup <span class="hlt">14</span>}<span class="hlt">C</span>-pyrene mineralization in non-adapted, pristine soils to a greater extent than {sup <span class="hlt">14</span>}<span class="hlt">C</span>-pyrene mineralization observed in pristine soils amended with a known PAH-mineralizing, microbial community. Mineralization of {sup <span class="hlt">14</span>}<span class="hlt">C</span>-chrysene in non-adapted, pristine soils was greater than NaN{sup 3} abiotic, control soils, but significantly less than {sup <span class="hlt">14</span>}<span class="hlt">C</span>-chrysene mineralization in pristine soils amended with a known PAH-mineralizing, microbial community. The major fate of {sup <span class="hlt">14</span>}<span class="hlt">C</span>-pyrene, {sup <span class="hlt">14</span>}<span class="hlt">C</span>-chrysene, and PAH mixtures is association with SOM.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5077992','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5077992"><span id="translatedtitle">Autoradiographic disposition of (1-methyl-/sup <span class="hlt">14</span>/<span class="hlt">C</span>)- and (2-/sup <span class="hlt">14</span>/<span class="hlt">C</span>)caffeine in mice</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lachance, M.P.; Marlowe, C.; Waddell, W.J.</p> <p>1983-11-01</p> <p>Male, C57B1/6J mice received either (1-methyl-<span class="hlt">14</span><span class="hlt">C</span>)caffeine or (2-<span class="hlt">14</span><span class="hlt">C</span>)caffeine via the tail vein at a dose of 0.7 or 11 mg/kg, respectively. At 0.1, 0.33, 1, 3, 9, and 24 hr after treatment, the mice were anesthetized with ether and frozen by immersion in dry ice/hexane. The mice were processed for whole-body autoradiography by the Ullberg technique; this procedure does not allow thawing or contact with solvents. All autoradiographs revealed some retention of radioactivity at early time intervals in the lacrimal glands, seminal vesicle fluid, nasal and olfactory epithelium, and retinal melanocytes. The remaining portion of the animal was densitometrically uniform except for the lower levels noted in the CNS and adipose tissues. Excretion of radioactivity by the liver and kidneys seems to be the major routes of elimination. Localization in the liver at late time intervals was confined principally to the centrilobular region. Late sites of retention, observed only after (1-methyl-<span class="hlt">14</span><span class="hlt">C</span>)caffeine administration, included the pancreas, minor and major salivary glands, splenic red pulp, thymal cortex, bone marrow, and gastrointestinal epithelium. Sites of localization present in both studies included the olfactory epithelium, lacrimal glands, hair follicles, and retinal melanocytes. Further studies are needed to determine whether the localization at these various sites is due to metabolic degradation, active transport, or possibly a specific receptor interaction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996LPI....27..549H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996LPI....27..549H"><span id="translatedtitle">PRIME Lab Radiocarbon Measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hillegonds, D. J.; Mueller, K. A.; Ma, X.; Lipschutz, M. E.</p> <p>1996-03-01</p> <p>The Purdue Rare Isotope Measurement Laboratory (PRIME Lab) is one of three NSF national facilities for accelerator mass spectrometry (AMS), and is the only one capable of determining six cosmogenic radionuclides: 10Be, <span class="hlt">14</span><span class="hlt">C</span>, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span>, 41Ca, and 129I. This abstract describes the current status of the radiocarbon analysis program at PRIME Lab.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title17-vol3/pdf/CFR-2011-title17-vol3-sec240-14c-3.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title17-vol3/pdf/CFR-2011-title17-vol3-sec240-14c-3.pdf"><span id="translatedtitle">17 CFR 240.<span class="hlt">14</span><span class="hlt">c</span>-3 - Annual report to be furnished security holders.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-04-01</p> <p>... security holders. 240.<span class="hlt">14</span><span class="hlt">c</span>-3 Section 240.<span class="hlt">14</span><span class="hlt">c</span>-3 Commodity and Securities Exchanges SECURITIES AND EXCHANGE... Section <span class="hlt">14</span>(<span class="hlt">c</span>) § 240.<span class="hlt">14</span><span class="hlt">c</span>-3 Annual report to be furnished security holders. (a) If the information statement... such meeting, of security holders at which directors of the registrant, other than an...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title17-vol3/pdf/CFR-2010-title17-vol3-sec240-14c-3.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title17-vol3/pdf/CFR-2010-title17-vol3-sec240-14c-3.pdf"><span id="translatedtitle">17 CFR 240.<span class="hlt">14</span><span class="hlt">c</span>-3 - Annual report to be furnished security holders.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-04-01</p> <p>... security holders. 240.<span class="hlt">14</span><span class="hlt">c</span>-3 Section 240.<span class="hlt">14</span><span class="hlt">c</span>-3 Commodity and Securities Exchanges SECURITIES AND EXCHANGE... Section <span class="hlt">14</span>(<span class="hlt">c</span>) § 240.<span class="hlt">14</span><span class="hlt">c</span>-3 Annual report to be furnished security holders. (a) If the information statement... such meeting, of security holders at which directors of the registrant, other than an...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23671077','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23671077"><span id="translatedtitle">182Hf-182W age dating of a <span class="hlt">26</span><span class="hlt">Al</span>-poor inclusion and implications for the origin of short-lived radioisotopes in the early Solar System.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Holst, Jesper C; Olsen, Mia B; Paton, Chad; Nagashima, Kazuhide; Schiller, Martin; Wielandt, Daniel; Larsen, Kirsten K; Connelly, James N; Jørgensen, Jes K; Krot, Alexander N; Nordlund, Ake; Bizzarro, Martin</p> <p>2013-05-28</p> <p>Refractory inclusions [calcium-aluminum-rich inclusions, (CAIs)] represent the oldest Solar System solids and provide information regarding the formation of the Sun and its protoplanetary disk. CAIs contain evidence of now extinct short-lived radioisotopes (e.g., (<span class="hlt">26</span>)<span class="hlt">Al</span>, (41)Ca, and (182)Hf) synthesized in one or multiple stars and added to the protosolar molecular cloud before or during its collapse. Understanding how and when short-lived radioisotopes were added to the Solar System is necessary to assess their validity as chronometers and constrain the birthplace of the Sun. Whereas most CAIs formed with the canonical abundance of (<span class="hlt">26</span>)<span class="hlt">Al</span> corresponding to (<span class="hlt">26</span>)<span class="hlt">Al</span>/(27)Al of ∼5 × 10(-5), rare CAIs with fractionation and unidentified nuclear isotope effects (FUN CAIs) record nucleosynthetic isotopic heterogeneity and (<span class="hlt">26</span>)<span class="hlt">Al</span>/(27)Al of <5 × 10(-6), possibly reflecting their formation before canonical CAIs. Thus, FUN CAIs may provide a unique window into the earliest Solar System, including the origin of short-lived radioisotopes. However, their chronology is unknown. Using the (182)Hf-(182)W chronometer, we show that a FUN CAI recording a condensation origin from a solar gas formed coevally with canonical CAIs, but with (<span class="hlt">26</span>)<span class="hlt">Al</span>/(27)Al of ∼3 × 10(-6). The decoupling between (182)Hf and (<span class="hlt">26</span>)<span class="hlt">Al</span> requires distinct stellar origins: steady-state galactic stellar nucleosynthesis for (182)Hf and late-stage contamination of the protosolar molecular cloud by a massive star(s) for (<span class="hlt">26</span>)<span class="hlt">Al</span>. Admixing of stellar-derived (<span class="hlt">26</span>)<span class="hlt">Al</span> to the protoplanetary disk occurred during the epoch of CAI formation and, therefore, the (<span class="hlt">26</span>)<span class="hlt">Al</span>-(26)Mg systematics of CAIs cannot be used to define their formation interval. In contrast, our results support (182)Hf homogeneity and chronological significance of the (182)Hf-(182)W clock. PMID:23671077</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23671077','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23671077"><span id="translatedtitle">182Hf-182W age dating of a <span class="hlt">26</span><span class="hlt">Al</span>-poor inclusion and implications for the origin of short-lived radioisotopes in the early Solar System.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Holst, Jesper C; Olsen, Mia B; Paton, Chad; Nagashima, Kazuhide; Schiller, Martin; Wielandt, Daniel; Larsen, Kirsten K; Connelly, James N; Jørgensen, Jes K; Krot, Alexander N; Nordlund, Ake; Bizzarro, Martin</p> <p>2013-05-28</p> <p>Refractory inclusions [calcium-aluminum-rich inclusions, (CAIs)] represent the oldest Solar System solids and provide information regarding the formation of the Sun and its protoplanetary disk. CAIs contain evidence of now extinct short-lived radioisotopes (e.g., (<span class="hlt">26</span>)<span class="hlt">Al</span>, (41)Ca, and (182)Hf) synthesized in one or multiple stars and added to the protosolar molecular cloud before or during its collapse. Understanding how and when short-lived radioisotopes were added to the Solar System is necessary to assess their validity as chronometers and constrain the birthplace of the Sun. Whereas most CAIs formed with the canonical abundance of (<span class="hlt">26</span>)<span class="hlt">Al</span> corresponding to (<span class="hlt">26</span>)<span class="hlt">Al</span>/(27)Al of ∼5 × 10(-5), rare CAIs with fractionation and unidentified nuclear isotope effects (FUN CAIs) record nucleosynthetic isotopic heterogeneity and (<span class="hlt">26</span>)<span class="hlt">Al</span>/(27)Al of <5 × 10(-6), possibly reflecting their formation before canonical CAIs. Thus, FUN CAIs may provide a unique window into the earliest Solar System, including the origin of short-lived radioisotopes. However, their chronology is unknown. Using the (182)Hf-(182)W chronometer, we show that a FUN CAI recording a condensation origin from a solar gas formed coevally with canonical CAIs, but with (<span class="hlt">26</span>)<span class="hlt">Al</span>/(27)Al of ∼3 × 10(-6). The decoupling between (182)Hf and (<span class="hlt">26</span>)<span class="hlt">Al</span> requires distinct stellar origins: steady-state galactic stellar nucleosynthesis for (182)Hf and late-stage contamination of the protosolar molecular cloud by a massive star(s) for (<span class="hlt">26</span>)<span class="hlt">Al</span>. Admixing of stellar-derived (<span class="hlt">26</span>)<span class="hlt">Al</span> to the protoplanetary disk occurred during the epoch of CAI formation and, therefore, the (<span class="hlt">26</span>)<span class="hlt">Al</span>-(26)Mg systematics of CAIs cannot be used to define their formation interval. In contrast, our results support (182)Hf homogeneity and chronological significance of the (182)Hf-(182)W clock.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/7980','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/7980"><span id="translatedtitle">Human folate metabolism using <span class="hlt">14</span><span class="hlt">C</span>-accelerator mass spectrometry</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Clifford, A. J.; Arjomand, A.; Duecker, S. R.; Johnson, H.; Schneider, P. D.; Zulim, R. A.; Bucholz, B. A.; Vogel, J. S.</p> <p>1999-03-25</p> <p>Folate is a water soluble vitamin required for optimal health, growth and development. It occurs naturally in various states of oxidation of the pteridine ring and with varying lengths to its glutamate chain. Folates function as one-carbon donors through methyl transferase catalyzed reactions. Low-folate diets, especially by those with suboptimal methyltransferase activity, are associated with increased risk of neural tube birth defects in children, hyperhomocysteinemic heart disease, and cancer in adults. Rapidly dividing (neoplastic) cells have a high folate need for DNA synthesis. Chemical analogs of folate (antifolates) that interfere with folate metabolism are used as therapeutic agents in cancer treatment. Although much is known about folate chemistry, metabolism of this vitamin in vivo in humans is not well understood. Since folate levels in blood and tissues are very low and methods to measure them are inadequate, the few previous studies that have examined folate metabolism used large doses of radiolabeled folic acid in patients with Hodgkin's disease and cancer (Butterworth et al. 1969, Krumdieck et al. 1978). A subsequent protocol using deuterated folic acid was also insufficiently sensitive to trace a physiologic folate dose (Stites et al. 1997). Accelerator mass spectrometry (AMS) is an emerging bioanalytical tool that overcomes the limitations of traditional mass spectrometry and of decay counting of long lived radioisotopes (Vogel et al. 1995). AMS can detect attomolar concentrations of <span class="hlt">14</span> <span class="hlt">C</span> in milligram-sized samples enabling in vivo radiotracer studies in healthy humans. We used AMS to study the metabolism of a physiologic 80 nmol oral dose of <span class="hlt">14</span> <span class="hlt">C</span>-folic acid (1/6 US RDA) by measuring the <span class="hlt">14</span> <span class="hlt">C</span>-folate levels in serial plasma, urine and feces samples taken over a 150-day period after dosing a healthy adult volunteer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1586292','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1586292"><span id="translatedtitle">Assessment of the <span class="hlt">14</span><span class="hlt">C</span>-Glycocholic Acid Breath Test</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>James, O. F. W.; Agnew, J. E.; Bouchier, I. A. D.</p> <p>1973-01-01</p> <p>The 1-(<span class="hlt">14</span><span class="hlt">C</span>)-glycine-glycocholic-acid breath test has been performed on 104 subjects and a normal range established. Abnormal results due to bacterial deconjugation of bile salts were found not only in patients with the “contaminated bowel” syndrome and in those with ileal resection but also in a third group, patients with cholangitis. Abnormal results were also found in patients with gastrocolic fistula and staphylococcal enterocolitis, while mildly abnormal results were also found in some patients with liver disease. PMID:4718834</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NIMPB.361..659D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NIMPB.361..659D"><span id="translatedtitle">A high resolution method for <span class="hlt">14</span><span class="hlt">C</span> analysis of a coral from South China Sea: Implication for "AD 775" <span class="hlt">14</span><span class="hlt">C</span> event</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ding, Ping; Shen, Chengde; Yi, Weixi; Wang, Ning; Ding, Xingfang; Liu, Kexin; Fu, Dongpo; Liu, Weiguo; Liu, Yi</p> <p>2015-10-01</p> <p>A pre-heating method that improves the background and precision of <span class="hlt">14</span><span class="hlt">C</span> dating significantly was applied for fossil coral dating with high resolution in our lab in Guangzhou Institute of Geochemistry, Chinese Academy of Sciences (GIGCAS). The reaction tube is heated under 300 °C in a vacuum line before it is used for graphitization. The method can reduce the contamination absorbed in TiH2, Zn and Fe power placed in the graphitization tube. With the pre-heating and average drilling method, bi-weekly resolution <span class="hlt">14</span><span class="hlt">C</span> dating in a fossil coral is carried out to investigate the "AD 775 <span class="hlt">14</span><span class="hlt">C</span> spike event". Different from the tree ring <span class="hlt">14</span><span class="hlt">C</span> archives with the <span class="hlt">14</span><span class="hlt">C</span> spike of ∼15‰ (Δ<span class="hlt">14</span><span class="hlt">C</span>), the <span class="hlt">14</span><span class="hlt">C</span> spike in the coral shows an abrupt peak of 45‰ and two smaller spikes of Δ<span class="hlt">14</span><span class="hlt">C</span> > 20‰ in half a year in AD 776. And then, the <span class="hlt">14</span><span class="hlt">C</span> content in coral decreases gradually in AD 777. The peak time of the <span class="hlt">14</span><span class="hlt">C</span> spike event likely occurs in the summer of AD 776 according to the δ18O variation in coral. High-resolution dating of <span class="hlt">14</span><span class="hlt">C</span> in coral provides not only a more detail process of the event than that from tree rings, but also the first report of the event from sea ecosystem. Both of them suggest an extraterrestrial origin of the event cause.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016QSRv..150..130S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016QSRv..150..130S"><span id="translatedtitle">Implications of <span class="hlt">36</span><span class="hlt">Cl</span> exposure ages from Skye, northwest Scotland for the timing of ice stream deglaciation and deglacial ice dynamics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Small, David; Rinterknecht, Vincent; Austin, William E. N.; Bates, Richard; Benn, Douglas I.; Scourse, James D.; Bourlès, Didier L.; Hibbert, Fiona D.</p> <p>2016-10-01</p> <p>Geochronological constraints on the deglaciation of former marine based ice streams provide information on the rates and modes by which marine based ice sheets have responded to external forcing factors such as climate change. This paper presents new <span class="hlt">36</span><span class="hlt">Cl</span> cosmic ray exposure dating from boulders located on two moraines (Glen Brittle and Loch Scavaig) in southern Skye, northwest Scotland. Ages from the Glen Brittle moraines constrain deglaciation of a major marine terminating ice stream, the Barra-Donegal Ice Stream that drained the former British-Irish Ice Sheet, depending on choice of production method and scaling model this occurred 19.9 ± 1.5-17.6 ± 1.3 ka ago. We compare this timing of deglaciation to existing geochronological data and changes in a variety of potential forcing factors constrained through proxy records and numerical models to determine what deglaciation age is most consistent with existing evidence. Another small section of moraine, the Scavaig moraine, is traced offshore through multibeam swath-bathymetry and interpreted as delimiting a later stillstand/readvance stage following ice stream deglaciation. Additional cosmic ray exposure dating from the onshore portion of this moraine indicate that it was deposited 16.3 ± 1.3-15.2 ± 0.9 ka ago. When calculated using the most up-to-date scaling scheme this time of deposition is, within uncertainty, the same as the timing of a widely identified readvance, the Wester Ross Readvance, observed elsewhere in northwest Scotland. This extends the area over which this readvance has potentially occurred, reinforcing the view that it was climatically forced.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFM.T51C..06D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFM.T51C..06D"><span id="translatedtitle">First Constraints On the Slip Rate of the Yammouneh Fault (Levant Fault System) Determined by Cosmogenic \\textsuperscript{<span class="hlt">36</span>}<span class="hlt">Cl</span> Exposure Dating of Offset Alluvial Fans</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Daëron, M.; Benedetti, L.; Tapponnier, P.; Sursock, A.; Finkel, R.</p> <p>2003-12-01</p> <p>The most active seismogenic structure along the eastern shore of the Mediterranean is the left-lateral strike-slip Levant fault, plate boundary between Arabia and Africa. To this day there is consensus neither on its present slip rate and segmentation, nor on the exact size and frequence of the earthquakes it generates. Between latitudes 33\\textsuperscript{o} N and 35\\textsuperscript{o} N in Lebanon, the Levant fault's trace veers eastwards by 24\\textsuperscript{o}, forming a 160km-long restraining bend, responsible for the uplift of Mount Lebanon (3083m). Most of the resulting transpressive deformation is partitioned between two main structures: the offshore Tripoli-Beirut thrust and the Yammouneh strike-slip fault, whose degree of seismogenic activity has been questioned (various estimations of its modern slip rate range from 0 to 8mm/yr). Using aerial photographs, satellite images, topographic maps and field observations, we mapped and measured left-laterally offset alluvial fans and gullies along the Yammouneh fault. The measured offsets range from less than 10m to about 3km. To constrain the slip rate of the Yammouneh fault, limestone cobbles were sampled on three alluvial fans, each offset by 40--50m. The concentrations of \\textsuperscript{<span class="hlt">36</span>}<span class="hlt">Cl</span>\\ and stable Chlorine in the 48 samples were measured by accelerator mass spectrometry at the LLNL-CAMS. The first results suggest an average slip rate of 5--10mm/yr along the Yammouneh fault in the last 8,000 years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014Geomo.219..201F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014Geomo.219..201F"><span id="translatedtitle"><span class="hlt">26</span><span class="hlt">Al</span>/10Be dating of an aeolian dust mantle soil in western New South Wales, Australia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fisher, Adrian; Fink, David; Chappell, John; Melville, Michael</p> <p>2014-08-01</p> <p>Aeolian dust mantle soils are an important element of many landscapes in south-eastern Australia, though the age of these aeolian deposits has not been radiometrically determined. At Fowlers Gap in western New South Wales, surface cobbles of silcrete and quartz overlie a stone-free, aeolian dust mantle soil, which has a thickness of about 1.6 m. The clay-rich aeolian dust deposit in turn lies upon a buried silcrete and quartz stone layer. Modelling in-situ cosmogenic <span class="hlt">26</span><span class="hlt">Al</span> and 10Be concentrations measured in both the surface quartz stones and in the buried quartz layer of rocks, reveals that each has experienced a complex exposure-burial history. Due to the absence of quartz stones or sand at intermediate depths, our cosmogenic <span class="hlt">26</span><span class="hlt">Al</span> and 10Be modelling was not able to determine a definitive mechanism of stone pavement formation and stone burial. Various scenarios of stone formation, transport, burial and exhumation were tested that constrain the age of the deposit to range from 0.9 ± 0.2 Ma to 1.8 ± 0.2 Ma, based largely on different assumptions taken for the time-dependency of the net sedimentation rate. This corresponds with the initiation of the Simpson Desert dune fields and the deflation of lakes in central Australia, which probably responded to the shift to longer-wavelength, larger-amplitude Quaternary glacial cycles at around 1 Ma. Sensitivity analyses were carried out to identify those parameters which better constrained model outputs. Within model errors, which largely are the result of analytical errors in measured <span class="hlt">26</span><span class="hlt">Al</span> and 10Be concentrations, all three competing theories of colluvial wash, upward displacement of stones, and cumulic pedogenesis are possible mechanisms for the formation of the surface stone pavement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21596675','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21596675"><span id="translatedtitle">Precise measurement of the half-life of the Fermi {beta} decay of {sup <span class="hlt">26</span>}<span class="hlt">Al</span>{sup m}</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Scott, Rebecca J.; Thompson, Maxwell N.; Rassool, Roger P.; O'Keefe, Graeme J.</p> <p>2011-08-15</p> <p>State-of-the-art signal digitization and analysis techniques have been used to measure the half-life of the Fermi {beta} decay of {sup <span class="hlt">26</span>}<span class="hlt">Al</span>{sup m}. The half-life was determined to be 6347.8 {+-} 2.5 ms. This new datum contributes to the experimental testing of the conserved-vector-current hypothesis and the required unitarity of the Cabibbo-Kobayashi-Maskawa matrix: two essential components of the standard model. Detailed discussion of the experimental techniques and data analysis and a thorough investigation of the statistical and systematic uncertainties are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70029271','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70029271"><span id="translatedtitle">Dating offset fans along the Mojave section of the San Andreas fault using cosmogenic <span class="hlt">26</span><span class="hlt">Al</span> and 10Be</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Matmon, A.; Schwartz, D.P.; Finkel, R.; Clemmens, S.; Hanks, T.</p> <p>2005-01-01</p> <p>Analysis of cosmogenic 10Be and <span class="hlt">26</span><span class="hlt">Al</span> in samples collected from exposed boulders (n = 20) and from buried sediment (n = 3) from offset fans along the San Andreas fault near Little Rock, California, yielded ages, ranging from 16 to 413 ka, which increase with distance from their source at the mouth of Little Rock Creek. In order to determine the age of the relatively younger fans, the erosion rate of the boulders and the cosmogenic nuclide inheritance from exposure prior to deposition in the fan were established. Cosmogenic nuclide inheritance values that range between 8.5 ?? 103 and 196 ?? 103 atoms 10Be g-1 quartz were determined by measuring the concentrations and ratios of 10Be and <span class="hlt">26</span><span class="hlt">Al</span> in boulders (n = 10) and fine sediment (n = 7) at the outlet of the present active stream. Boulder erosion rate, ranging between 17 and 160 mm k.y.-1, was estimated by measuring 10Be and <span class="hlt">26</span><span class="hlt">Al</span> concentrations in nearby bedrock outcrops (n = 8). Since the boulders on the fans represent the most resistant rocks in this environment, we used the lowest rate for the age calculations. Monte Carlo simulations were used to determine ages of 16 ?? 5 and 29 ?? 7 ka for the two younger fan surfaces. Older fans (older than 100 ka) were dated by analyzing 10Be and <span class="hlt">26</span><span class="hlt">Al</span> concentrations in buried sand samples. The ages of the three oldest fans range between 227 ?? 242 and 413 ?? 185 ka. Although fan age determinations are accompanied by large uncertainties, the results of this study show a clear trend of increasing fan ages with increasing distance from the source near Little Rock Creek and provide a long-term slip rate along this section of the San Andreas fault. Slip rate along the Mojave section of the San Andreas fault for the past 413 k.y. can be determined in several ways. The average slip rate calculated from the individual fan ages is 4.2 ?? 0.9 cm yr-1. A linear regression through the data points implies a slip rate of 3.7 ?? 1.0 cm yr-1. A most probable slip rate of 3.0 ?? 1.0 cm yr-1 is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992Metic..27Q.241K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992Metic..27Q.241K"><span id="translatedtitle">The Prediction of the Saturated Activity of <span class="hlt">26</span><span class="hlt">Al</span> in Non-Antarctic Stony Meteorites from their Chemical Compositions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Keith, J. E.; Heydegger, H. R.</p> <p>1992-07-01</p> <p>We have assembled from the literature a database of over 300 non-Antarctic stony meteorites, containing information about their chemical composition, date of fall, total mass, and gas exposure age, etc. We have developed an iterative algorithm using weighted linear multivariate regression, which surveys all the independent variables in the database, recommends the best 26 models (combinations of variables) for the prediction of Al activity, and using those models, performs weighted linear multivariate regressions. By requiring that the residuals be normally distributed, under- and super-saturated meteorites are discovered and eliminated. This process is iterated until a stable solution is obtained. As a result, we obtained a set of 128 saturated, 50 unsaturated, and 10 supersaturated meteorites. We find that the expression: ^<span class="hlt">26</span><span class="hlt">Al</span> = (5.28+-0.81) . Al + (2.59+- 0.06) . Si + (1.57+-0.39) . S + (1.52+-0.59) . Ca, Chi^2(sub)nu = 2.59, where the elemental concentration is given in weight 26%, is the best predictor of the saturated ^<span class="hlt">26</span><span class="hlt">Al</span> content of a stony meteorite. We find no evidence of bias or crippling multicollinearity in this expression. About one half of the remaining variability cannot be attributed to uncertainties in the determination of the ^<span class="hlt">26</span><span class="hlt">Al</span> content and thus must be attributed to variations in orbit, shielding, etc. We compare our results (see figure) with those of other workers (1,2,3,4), and examine the probable causes of the disagreements displayed there. We show that saturated ^<span class="hlt">26</span><span class="hlt">Al</span> is distributed among all classes of meteorites in about the same way, with the exception of the carbonaceous chondrites and the eucrites, which both have about the same excess proportion of unsaturation. We examine the question of the convergence of expressions derived from regressions on chemical composition to the predictive expressions derived from integrals of particle fluxes and nuclear reaction cross sections and show that they need not converge. We examine the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NIMPB.361..559T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NIMPB.361..559T"><span id="translatedtitle">Accelerator mass spectrometry analysis of <span class="hlt">14</span><span class="hlt">C</span>-oxaliplatin concentrations in biological samples and <span class="hlt">14</span><span class="hlt">C</span> contents in biological samples and antineoplastic agents</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Toyoguchi, Teiko; Kobayashi, Takeshi; Konno, Noboru; Shiraishi, Tadashi; Kato, Kazuhiro; Tokanai, Fuyuki</p> <p>2015-10-01</p> <p>Accelerator mass spectrometry (AMS) is expected to play an important role in microdose trials. In this study, we measured the <span class="hlt">14</span><span class="hlt">C</span> concentration in <span class="hlt">14</span><span class="hlt">C</span>-oxaliplatin-spiked serum, urine and supernatant of fecal homogenate samples in our Yamagata University (YU) - AMS system. The calibration curves of <span class="hlt">14</span><span class="hlt">C</span> concentration in serum, urine and supernatant of fecal homogenate were linear (the correlation coefficients were ⩾0.9893), and the precision and accuracy was within the acceptance criteria. To examine a <span class="hlt">14</span><span class="hlt">C</span> content of water in three vacuum blood collection tubes and a syringe were measured. <span class="hlt">14</span><span class="hlt">C</span> was not detected from water in these devices. The mean <span class="hlt">14</span><span class="hlt">C</span> content in urine samples of 6 healthy Japanese volunteers was 0.144 dpm/mL, and the intra-day fluctuation of <span class="hlt">14</span><span class="hlt">C</span> content in urine from a volunteer was little. The antineoplastic agents are administered to the patients in combination. Then, <span class="hlt">14</span><span class="hlt">C</span> contents of the antineoplastic agents were quantitated. <span class="hlt">14</span><span class="hlt">C</span> contents were different among 10 antineoplastic agents; <span class="hlt">14</span><span class="hlt">C</span> contents of paclitaxel injection and docetaxel hydrate injection were higher than those of the other injections. These results indicate that our quantitation method using YU-AMS system is suited for microdosing studies and that measurement of baseline and co-administered drugs might be necessary for the studies in low concentrations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3670341','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3670341"><span id="translatedtitle">182Hf–182W age dating of a <span class="hlt">26</span><span class="hlt">Al</span>-poor inclusion and implications for the origin of short-lived radioisotopes in the early Solar System</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Holst, Jesper C.; Olsen, Mia B.; Paton, Chad; Nagashima, Kazuhide; Schiller, Martin; Wielandt, Daniel; Larsen, Kirsten K.; Connelly, James N.; Jørgensen, Jes K.; Krot, Alexander N.; Nordlund, Åke; Bizzarro, Martin</p> <p>2013-01-01</p> <p>Refractory inclusions [calcium–aluminum-rich inclusions, (CAIs)] represent the oldest Solar System solids and provide information regarding the formation of the Sun and its protoplanetary disk. CAIs contain evidence of now extinct short-lived radioisotopes (e.g., <span class="hlt">26</span><span class="hlt">Al</span>, 41Ca, and 182Hf) synthesized in one or multiple stars and added to the protosolar molecular cloud before or during its collapse. Understanding how and when short-lived radioisotopes were added to the Solar System is necessary to assess their validity as chronometers and constrain the birthplace of the Sun. Whereas most CAIs formed with the canonical abundance of <span class="hlt">26</span><span class="hlt">Al</span> corresponding to <span class="hlt">26</span><span class="hlt">Al</span>/27Al of ∼5 × 10−5, rare CAIs with fractionation and unidentified nuclear isotope effects (FUN CAIs) record nucleosynthetic isotopic heterogeneity and <span class="hlt">26</span><span class="hlt">Al</span>/27Al of <5 × 10−6, possibly reflecting their formation before canonical CAIs. Thus, FUN CAIs may provide a unique window into the earliest Solar System, including the origin of short-lived radioisotopes. However, their chronology is unknown. Using the 182Hf–182W chronometer, we show that a FUN CAI recording a condensation origin from a solar gas formed coevally with canonical CAIs, but with <span class="hlt">26</span><span class="hlt">Al</span>/27Al of ∼3 × 10−6. The decoupling between 182Hf and <span class="hlt">26</span><span class="hlt">Al</span> requires distinct stellar origins: steady-state galactic stellar nucleosynthesis for 182Hf and late-stage contamination of the protosolar molecular cloud by a massive star(s) for <span class="hlt">26</span><span class="hlt">Al</span>. Admixing of stellar-derived <span class="hlt">26</span><span class="hlt">Al</span> to the protoplanetary disk occurred during the epoch of CAI formation and, therefore, the 26Al–26Mg systematics of CAIs cannot be used to define their formation interval. In contrast, our results support 182Hf homogeneity and chronological significance of the 182Hf–182W clock. PMID:23671077</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/7100651','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/7100651"><span id="translatedtitle">Metabolism and excretion of [<span class="hlt">14</span><span class="hlt">C</span>] verruculogen in a sheep.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Perera, K P; Mantle, P G; Penny, R H</p> <p>1982-05-01</p> <p>[<span class="hlt">14</span><span class="hlt">C</span>] Verruculogen (75 micrograms/kg) was given intravenously to a sheep under barbiturate anaesthesia to prevent the severe tremor and convulsions which would otherwise have occurred. Two hours later 28 per cent of the tremorgenic mycotoxin was detected in the liver, bile and small intestine. Approximately 0.5 per cent was excreted in the urine. Trace amounts of radiolabel were detected in the cortex and corpus striatum of the brain. Verruculogen was metabolised by the liver and converted completely to four more polar products, including two isomeric forms of desoxy-verruculogen and the weakly tremorgenic mycotoxin TR-2. The principal and most polar metabolite excreted is probably an isomer of TR-2. PMID:7100651</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014QSRv...90..106Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014QSRv...90..106Z"><span id="translatedtitle">Mid-Holocene cluster of large-scale landslides revealed in the Southwestern Alps by <span class="hlt">36</span><span class="hlt">Cl</span> dating. Insight on an Alpine-scale landslide activity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zerathe, Swann; Lebourg, Thomas; Braucher, Régis; Bourlès, Didier</p> <p>2014-04-01</p> <p>Although it is generally assumed that the internal structure of a slope (e.g. lithology and rock mass properties, inherited faults and heterogeneities, etc.) is preponderant for the progressive development of large-scale landslides, the ability to identify triggering factors responsible for final slope failures such as glacial debuttressing, seismic activities or climatic changes, especially when considering landslide cluster at an orogen-scale, is still debated. Highlighting in this study the spatial and temporal concordant clustering of deep-seated slope failures in the external Southwestern Alps, we discuss and review the possible causes for such wide-spread slope instabilities at both local and larger (Alpine) scale. High resolution field mapping coupled with electrical resistivity tomography first allows establishing an inventory of large landslides in the Southwestern Alps, determining their structural model, precising their depth limit (100-200 m) as well as the involved rock volumes (>107 m3). We show that they developed in the same geostructural context of thick mudstone layers overlain by faulted limestone and followed a block-spread model of deformation that could evolve in rock-collapse events. Cosmic ray exposure dating (CRE), using both <span class="hlt">36</span><span class="hlt">Cl</span> and 10Be in coexisting limestone and chert, respectively, has been carried out from the main scarps of six Deep Seated Landslides (DSL) and leads to landslide-failure CRE ages ranging from 3.7 to 4.7 ka. They highlighted: (i) mainly single and fast ruptures and (ii) a possible concomitant initiation with a main peak of activity between 3.3 and 5.1 ka, centered at ca 4.2 ka. Because this region was not affected by historical glaciations events, landslide triggering by glacial unloading can be excluded. The presented data combined with field observations preferentially suggest that these failures were climatically driven and were most likely controlled by high pressure changes in the karstic medium. In effect, the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6524602','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6524602"><span id="translatedtitle">Effect of endomycorrhizae on the bioavailability of bound sup <span class="hlt">14</span> <span class="hlt">C</span> residues to onion plants from an organic soil treated with ( sup <span class="hlt">14</span> <span class="hlt">C</span>)fonofos</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Nelson, S.D.; Khan, S.U. )</p> <p>1990-03-01</p> <p>Uptake of bound {sup <span class="hlt">14</span>}<span class="hlt">C</span> residues from an organic soil treated with radiolabeled fonofos (O-ethyl S-phenyl ethylphosphonodithioate) by selected Glomus endomycorrhiza and onion roots was studied. The hyphae of endomycorrhizal associations were capable of removing {sup <span class="hlt">14</span>}<span class="hlt">C</span> residues from the soil and transporting them to onion plants. Bioavailability of soil-bound {sup <span class="hlt">14</span>}<span class="hlt">C</span> residues, as measured by {sup <span class="hlt">14</span>}<span class="hlt">C</span> residue content in onion, was increased 32 and 40% over that of nonmycorrhizal plants by hyphae of Glomus intraradices and Glomus vesiculiferium, respectively. The data suggest that under field conditions endomycorrhizal infection may greatly increase the bioavailability of soil-bound pesticide residues to plants.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5777403','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5777403"><span id="translatedtitle">Defective (U-<span class="hlt">14</span> <span class="hlt">C</span>) palmitic acid oxidation in Duchenne muscular dystrophy</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Carroll, J.E.; Norris, B.J.; Brooke, M.H.</p> <p>1985-01-01</p> <p>Compared with normal skeletal muscle, muscle from patients with Duchenne dystrophy had decreased (U-<span class="hlt">14</span> <span class="hlt">C</span>) palmitic acid oxidation. (1-<span class="hlt">14</span> <span class="hlt">C</span>) palmitic acid oxidation was normal. These results may indicate a defect in intramitochondrial fatty acid oxidation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6142673','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6142673"><span id="translatedtitle">Percutaneous absorption of ( sup <span class="hlt">14</span> <span class="hlt">C</span>)DDT and ( sup <span class="hlt">14</span> <span class="hlt">C</span>)benzo(a)pyrene from soil</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wester, R.C.; Maibach, H.I.; Bucks, D.A.; Sedik, L.; Melendres, J.; Liao, C.; DiZio, S. )</p> <p>1990-10-01</p> <p>The objective was to determine percutaneous absorption of DDT and benzo(a)pyrene in vitro and in vivo from soil into and through skin. Soil (Yolo County 65-California-57-8; 26% sand, 26% clay, 48% silt) was passed through 10-, 20-, and 48-mesh sieves. Soil then retained by 80-mesh was mixed with (<span class="hlt">14</span><span class="hlt">C</span>)-labeled chemical at 10 ppm. Acetone solutions at 10 ppm were prepared for comparative analysis. Human cadaver skin was dermatomed to 500 microns and used in glass diffusion cells with human plasma as the receptor fluid (3 ml/hr flow rate) for a 24-hr skin application time. With acetone vehicle, DDT (18.1 +/- 13.4%) readily penetrated into human skin. Significantly less DDT (1.0 +/- 0.7%) penetrated into human skin from soil. DDT would not partition from human skin into human plasma in the receptor phase (less than 0.1%). With acetone vehicle, benzo(a)pyrene (23.7 +/- 9.7%) readily penetrated into human skin. Significantly less benzo(a)pyrene (1.4 +/- 0.9%) penetrated into human skin from soil. Benzo(a)pyrene would not partition from human skin into human plasma in the receptor phase (less than 0.1%). Substantivity (skin retention) was investigated by applying <span class="hlt">14</span><span class="hlt">C</span>-labeled chemical to human skin in vitro for only 25 min. After soap and water wash, 16.7 +/- 13.2% of DDT applied in acetone remained absorbed to skin. With soil only 0.25 +/- 0.11% of DDT remained absorbed to skin. After soap and water wash 5.1 +/- 2.1% of benzo(a)pyrene applied in acetone remained absorbed to skin. With soil only 0.14 +/- 0.13% of benzo(a)pyrene remained absorbed to skin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=151303&keyword=nursing&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=79233299&CFTOKEN=94321220','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=151303&keyword=nursing&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=79233299&CFTOKEN=94321220"><span id="translatedtitle">DISTRIBUTION OF <span class="hlt">14</span><span class="hlt">C</span>-ATRAZINE FOLLOWING AN ACUTE LACTATIONAL EXPOSURE IN THE WISTAR RAT.</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>The purpose of the present study was to examine the distribution of atrazine in the lactating dam and suckling neonate following an acute exposure to either 2 or 4 mg/kg <span class="hlt">14</span><span class="hlt">C</span>-atrazine (<span class="hlt">14</span><span class="hlt">C</span>-ATR) by gavage. <span class="hlt">14</span><span class="hlt">C</span>-ATR was administered to the nursing dam on postnatal day 3 by oral gavag...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NIMPB.361..354S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NIMPB.361..354S"><span id="translatedtitle"><span class="hlt">14</span><span class="hlt">C</span> determination in different bio-based products</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Santos Arévalo, Francisco-Javier; Gómez Martínez, Isabel; Agulló García, Lidia; Reina Maldonado, María-Teresa; García León, Manuel</p> <p>2015-10-01</p> <p>Radiocarbon determination can be used as a tool to investigate the presence of biological elements in different bio-based products, such as biodiesel blends. These products may also be produced from fossil materials obtaining the same final molecules, so that composition is chemically indistinguishable. The amount of radiocarbon in these products can reveal how much of these biological elements have been used, usually mixed with petrol derived components, free of <span class="hlt">14</span><span class="hlt">C</span>. Some of these products are liquid and thus the handling at the laboratory is not as straightforward as with solid samples. At Centro Nacional de Aceleradores (CNA) we have tested the viability of these samples using a graphitization system coupled to an elemental analyzer used for combustion of the samples, thus avoiding any vacuum process. Samples do not follow any chemical pre-treatment procedure and are directly graphitized. Specific equipment for liquid samples related to the elemental analyzer was tested. Measurement of samples was performed by low-energy AMS at the 1 MV HVEE facility at CNA, paying special attention to background limits and reproducibility during sample preparation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70016960','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70016960"><span id="translatedtitle">Comparison of <span class="hlt">14</span><span class="hlt">C</span> ages of hydrothermal petroleums</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Simoneit, B.R.T.; Kvenvolden, K.A.</p> <p>1994-01-01</p> <p>In order to set limits on the time frame of formation of hydrothermal petroleum, we have obtained <span class="hlt">14</span><span class="hlt">C</span> ages on samples from three diverse regions; Gulf of California (Guaymas Basin), Northeast Pacific Ocean (Escanaba Trough and Middle Valley), and the East African Rift (Tanganyika Trough). The results date the source of carbon and therefore provide maximum ages for the formation and emplacement of the hydrothermal petroleums. The youngest petroleum occurs iin the Souther Trough of Guaymas Basin (3200-6600 yr, mean 4692 yr); in the Northern Trough the petroleum is slightly older (7400 yr). Significantly older hydrothermal petroleum occurs in Escanaba Trough (17,000 yr) and Middle Valley (29,000 yr). A continental example from the East African Rift has an age of 25,000 yr, comparable to the ages observed in the oceanic samples from the Northeast Pacific Ocean. These ages affirm that hydrothermal petroleum formation is a very rapid process and took place some time between the latest Pleistocene and the present in these active hydrothermal systems. ?? 1994.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5965636','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5965636"><span id="translatedtitle">Effects of Pseudomonas species on the release of bound sup <span class="hlt">14</span> <span class="hlt">C</span> residues from soil treated with ( sup <span class="hlt">14</span> <span class="hlt">C</span>)atrazine</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Khan, S.U.; Behki, R.M. )</p> <p>1990-11-01</p> <p>The release of bound (nonextractable) {sup <span class="hlt">14</span>}<span class="hlt">C</span> residues from soil previously treated with ({sup <span class="hlt">14</span>}<span class="hlt">C</span>)atrazine was investigated by incubation of the solvent-extracted soil with two species of Pseudomonas capable of metabolizing atrazine. The two species, 192 and 194, released bound {sup <span class="hlt">14</span>}<span class="hlt">C</span> residues from the soil. Addition of glucose, known to increase microbiological activities, to the incubated soil appeared to enhance the release of soil-bound {sup <span class="hlt">14</span>}<span class="hlt">C</span> residues, in particular in the presence of Pseudomonas species 192. The {sup <span class="hlt">14</span>}<span class="hlt">C</span> bound residues in soil, mainly present as the parent compound and its hydroxy and monodealkylated analogues, were released into the incubation mixture and were subsequently metabolized by the two species involving dechlorination and dealkylation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeCoA.169...99K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeCoA.169...99K"><span id="translatedtitle"><span class="hlt">26</span><span class="hlt">Al</span>-26Mg chronology and oxygen isotope distributions of multiple melting for a Type C CAI from Allende</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kawasaki, Noriyuki; Kato, Chizu; Itoh, Shoichi; Wakaki, Shigeyuki; Ito, Motoo; Yurimoto, Hisayoshi</p> <p>2015-11-01</p> <p>Disequilibrium oxygen isotopic distributions of Ca-Al-rich inclusions (CAIs) correspond to multiple melting events in the solar nebula. <span class="hlt">26</span><span class="hlt">Al</span>-26Mg systematics may be applicable for age differences among such melting events. We have carried out a coordinated study of detailed petrographic observations and in-situ oxygen and magnesium isotope measurements for a Type C CAI, EK1-04-2, from the Allende CV3 meteorite to determine the melting events and their ages. The CAI consists mainly of spinel, anorthite, olivine, and pyroxene, and has a core and mantle structure. Petrography of the core suggests that the crystallization sequence of the core minerals is from spinel, anorthite, olivine, and to pyroxene. The mantle has the same mineral assemblage as the core, and shows incomplete melting and solidification textures. Oxygen isotopic compositions of the minerals are distributed along the carbonaceous chondrite anhydrous mineral (CCAM) line (δ18O = -44‰ to +9‰), which indicates to preserve a chemical disequilibrium status in the CAI. Spinel shows a 16O-rich signature (δ18O ∼ -43‰), while anorthite is 16O-poor (δ18O ∼ +8‰). Olivine and pyroxene in the core have the same oxygen isotopic composition (δ18O ∼ -15‰), which indicates their equilibrium. Olivine and pyroxene in the mantle have variable oxygen isotopic compositions and are slightly depleted in 16O (δ18O = -13‰ to -4‰) compared with the same minerals in the core. The <span class="hlt">26</span><span class="hlt">Al</span>-26Mg systematics is consistent with the disequilibrium status observed according to the petrography and oxygen isotopes. Spinel is plotted on a line of (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 = (3.5 ± 0.2) × 10-5, anorthite is plotted on a line of (-1 ± 5) × 10-7, and olivine and pyroxene in the core are plotted on a line of (-1 ± 7) × 10-6. Plots of olivine and pyroxene in the mantle are scattered below the isochron of these minerals in the core. This study indicates that the EK1-04-2 Type C CAI underwent multiple heating events after the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22167129','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22167129"><span id="translatedtitle">IMPACT OF A REVISED {sup 25}Mg(p, {gamma}){sup <span class="hlt">26</span>}<span class="hlt">Al</span> REACTION RATE ON THE OPERATION OF THE Mg-Al CYCLE</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Straniero, O.; Cristallo, S.; Imbriani, G.; DiLeva, A.; Limata, B.; Strieder, F.; Bemmerer, D.; Broggini, C.; Caciolli, A.; Corvisiero, P.; Costantini, H.; Lemut, A.; Formicola, A.; Gustavino, C.; Junker, M.; Elekes, Z.; Fueloep, Zs.; Gyuerky, Gy.; Gervino, G.; Guglielmetti, A.; and others</p> <p>2013-02-15</p> <p>Proton captures on Mg isotopes play an important role in the Mg-Al cycle active in stellar H-burning regions. In particular, low-energy nuclear resonances in the {sup 25}Mg(p, {gamma}){sup <span class="hlt">26</span>}<span class="hlt">Al</span> reaction affect the production of radioactive {sup <span class="hlt">26</span>}<span class="hlt">Al</span>{sup gs} as well as the resulting Mg/Al abundance ratio. Reliable estimations of these quantities require precise measurements of the strengths of low-energy resonances. Based on a new experimental study performed at the Laboratory for Underground Nuclear Astrophysics, we provide revised rates of the {sup 25}Mg(p, {gamma}){sup <span class="hlt">26</span>}<span class="hlt">Al</span>{sup gs} and the {sup 25}Mg(p, {gamma}){sup <span class="hlt">26</span>}<span class="hlt">Al</span> {sup m} reactions with corresponding uncertainties. In the temperature range 50-150 MK, the new recommended rate of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> {sup m} production is up to five times higher than previously assumed. In addition, at T = 100 MK, the revised total reaction rate is a factor of two higher. Note that this is the range of temperature at which the Mg-Al cycle operates in a H-burning zone. The effects of this revision are discussed. Due to the significantly larger {sup 25}Mg(p, {gamma}){sup <span class="hlt">26</span>}<span class="hlt">Al</span> {sup m} rate, the estimated production of {sup <span class="hlt">26</span>}<span class="hlt">Al</span>{sup gs} in H-burning regions is less efficient than previously obtained. As a result, the new rates should imply a smaller contribution from Wolf-Rayet stars to the galactic {sup <span class="hlt">26</span>}<span class="hlt">Al</span> budget. Similarly, we show that the asymptotic giant branch (AGB) extra-mixing scenario does not appear able to explain the most extreme values of {sup <span class="hlt">26</span>}<span class="hlt">Al</span>/{sup 27}Al, i.e., >10{sup -2}, found in some O-rich presolar grains. Finally, the substantial increase of the total reaction rate makes the hypothesis of self-pollution by massive AGBs a more robust explanation for the Mg-Al anticorrelation observed in globular-cluster stars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007NIMPB.259..600F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007NIMPB.259..600F"><span id="translatedtitle">An inter-comparison of 10Be and <span class="hlt">26</span><span class="hlt">Al</span> AMS reference standards and the 10Be half-life</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fink, David; Smith, Andrew</p> <p>2007-06-01</p> <p>We have completed a survey and inter-comparison of several 10Be and <span class="hlt">26</span><span class="hlt">Al</span> standard reference materials (SRMs) that are in routine use at various AMS laboratories to assess their relative values and the accuracy of their quoted nominal ratios. The accelerator measurement cycle, analysis procedure and setup used at the ANTARES AMS facility for this survey are described. We focused on a new set of 10Be and <span class="hlt">26</span><span class="hlt">Al</span> serial dilutions of standard reference materials (SRMs) prepared by Kuni Nishiizumii at the University of California, Berkeley, and found excellent systematic reproducibility and internal consistency. For other standard materials, minor deviations are evident even when the results have been recalibrated to a common half-life. In particular, we confirm that the NIST 10Be SRM-4325 has a 14% greater 10Be/Be ratio than that certified by NIST when it is calibrated against other SRMs whose ratios have been normalized to a common 1.5 Ma 10Be half-life. In order to investigate this apparent discrepancy, we report on the results of an absolute, normalization independent, measure of the NIST-4325 10Be/Be ratio. Within the constraints of this type of measurement and its systematic errors, we determine an absolute value for the 10Be/Be SRM-4325 ratio in the range 26,050 to 24,800 × 10-15 in support of the certified value of 26,800 × 10-15 given by NIST. We hesitate to directly infer as a consequence that the 10Be half-life is 1.34 Ma because such an inference is contingent on a direct and accurate specific activity in the parent solution, which at present is not available.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19779729','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19779729"><span id="translatedtitle">The use of hair as an indicator of occupational <span class="hlt">14</span><span class="hlt">C</span> contamination.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Stenström, Kristina; Unkel, Ingmar; Nilsson, Carl Magnus; Rääf, Christopher; Mattsson, Sören</p> <p>2010-03-01</p> <p>This paper presents a study in which the specific activity of (<span class="hlt">14</span>)<span class="hlt">C</span> in hair has been investigated as an easily determined bio-indicator of the integrated (<span class="hlt">14</span>)<span class="hlt">C</span> exposure (over several months). The study includes 28 Swedish workers handling (<span class="hlt">14</span>)<span class="hlt">C</span>-labelled compounds, or working in a (<span class="hlt">14</span>)<span class="hlt">C</span>-enriched environment. Hair samples from personnel at a Swedish nuclear power plant showed very low levels of (<span class="hlt">14</span>)<span class="hlt">C</span> contamination, if any. In contrast, personnel at the investigated research departments showed (<span class="hlt">14</span>)<span class="hlt">C</span> levels in hair of up to 60% above the natural specific activity of (<span class="hlt">14</span>)<span class="hlt">C</span>. Much higher levels, up to 80 times the natural specific activity of (<span class="hlt">14</span>)<span class="hlt">C</span>, were found in hair from individuals working at a pharmaceutical research laboratory. This contamination was, however, not solely an internal contamination. There were indications that most of the (<span class="hlt">14</span>)<span class="hlt">C</span> in the hair originated from airborne (<span class="hlt">14</span>)<span class="hlt">C</span>-compounds, which were adsorbed onto the hair. The difficulties in removing this external (<span class="hlt">14</span>)<span class="hlt">C</span> contamination prior to analysis are discussed, as are the possibilities of using accelerator mass spectrometry to analyse various types of samples for retrospective dose assessment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/1578510','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/1578510"><span id="translatedtitle">Percutaneous absorption of [<span class="hlt">14</span><span class="hlt">C</span>]chlordane from soil.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wester, R C; Maibach, H I; Sedik, L; Melendres, J; Liao, C L; DiZio, S</p> <p>1992-04-01</p> <p>The objective was to determine percutaneous absorption of chlordane in vitro and in vivo from soil into and through skin. The data are needed to calculate the absorbed dose of chlordane from soil, which is then used to assess the toxicity risk. Chlordane, an insecticide for which residues exist in soil, is restricted currently to use for termite control. Chlordane is highly lipophilic with little or no movement out of soil. Soil (Yolo County 65-California-57-8; 26% sand, 26% clay, 48% silt, 0.9% organic) was passed through 10-, 20-, and 48-mesh sieves. Soil then retained by 80-mesh was mixed with <span class="hlt">14</span><span class="hlt">C</span>-labeled chemical at 67 ppm. Acetone solutions were prepared for comparative analysis. Human cadaver skin was dermatomed to 500 microns and used in glass diffusion cells with human plasma as the receptor fluid (3 ml/h flow rate) for a 24-h skin application time. Chlordane concentration within skin from in vitro studies was 0.34 +/- 0.31% from soil and 10.8 +/- 8.2% from acetone vehicle (p less than .01). Individual variation from human skin sources was evident (p less than .008). Chlordane accumulation in human plasma receptor fluid was the same for soil (0.04 +/- 0.05%) and acetone (0.07% +/- 0.06%) formulations. Most of the remaining chlordane was recovered in the soap and water skin surface wash. In contrast, in vivo percutaneous absorption of chlordane in the rhesus monkey was the same for soil (4.2 +/- 1.8%) and acetone (6.0 +/- 2.8%) formulations (p = .29, nonsignificant). Multiple soap and water washings were necessary to remove chlordane from skin, suggesting that a single wash may not adequately remove all the chlordane. PMID:1578510</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/1578510','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/1578510"><span id="translatedtitle">Percutaneous absorption of [<span class="hlt">14</span><span class="hlt">C</span>]chlordane from soil.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wester, R C; Maibach, H I; Sedik, L; Melendres, J; Liao, C L; DiZio, S</p> <p>1992-04-01</p> <p>The objective was to determine percutaneous absorption of chlordane in vitro and in vivo from soil into and through skin. The data are needed to calculate the absorbed dose of chlordane from soil, which is then used to assess the toxicity risk. Chlordane, an insecticide for which residues exist in soil, is restricted currently to use for termite control. Chlordane is highly lipophilic with little or no movement out of soil. Soil (Yolo County 65-California-57-8; 26% sand, 26% clay, 48% silt, 0.9% organic) was passed through 10-, 20-, and 48-mesh sieves. Soil then retained by 80-mesh was mixed with <span class="hlt">14</span><span class="hlt">C</span>-labeled chemical at 67 ppm. Acetone solutions were prepared for comparative analysis. Human cadaver skin was dermatomed to 500 microns and used in glass diffusion cells with human plasma as the receptor fluid (3 ml/h flow rate) for a 24-h skin application time. Chlordane concentration within skin from in vitro studies was 0.34 +/- 0.31% from soil and 10.8 +/- 8.2% from acetone vehicle (p less than .01). Individual variation from human skin sources was evident (p less than .008). Chlordane accumulation in human plasma receptor fluid was the same for soil (0.04 +/- 0.05%) and acetone (0.07% +/- 0.06%) formulations. Most of the remaining chlordane was recovered in the soap and water skin surface wash. In contrast, in vivo percutaneous absorption of chlordane in the rhesus monkey was the same for soil (4.2 +/- 1.8%) and acetone (6.0 +/- 2.8%) formulations (p = .29, nonsignificant). Multiple soap and water washings were necessary to remove chlordane from skin, suggesting that a single wash may not adequately remove all the chlordane.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/756734','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/756734"><span id="translatedtitle">Update on terrestrial ages of Antarctic meteorites</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Welten, K C; Nishiizumi, K; Caffee, M W</p> <p>2000-01-14</p> <p>Terrestrial ages of Antarctic meteorites are one of the few parameters that will help us to understand the meteorite concentration mechanism on blue-ice fields. Traditionally, terrestrial ages were determined on the basis of {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> in the metal phase, which has an uncertainty of about 70 ky. For young meteorites (< 40 ky), the terrestrial age is usually and most accurately determined using {sup <span class="hlt">14</span>}<span class="hlt">C</span> in the stone phase. In recent years two methods have been developed which are independent of shielding effects, the {sup 10}Be-{sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/{sup 10}Be method and the {sup 41}Ca/{sup <span class="hlt">36</span>}<span class="hlt">Cl</span> method. These methods have reduced the typical uncertainties in terrestrial ages by a factor of 2, to about 30 ky. The {sup 10}Be-{sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/{sup 10}Be method is quite dependent on the exposure age, which is unknown for most Antarctic meteorites. The authors therefore also attempt to use the relation between {sup <span class="hlt">26</span>}<span class="hlt">Al</span> and {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/{sup <span class="hlt">26</span>}<span class="hlt">Al</span> to derive a terrestrial age less dependent on the exposure age. The authors have measured the concentrations of cosmogenic {sup 10}Be, {sup <span class="hlt">26</span>}<span class="hlt">Al</span> and {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> in the metal phase of {approximately} 70 Antarctic meteorites, from more than 10 different ice-fields, including many new ones. They then discuss the trends in terrestrial ages of meteorites from different ice-fields.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5159693','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5159693"><span id="translatedtitle">Metabolism of ( sup <span class="hlt">14</span> <span class="hlt">C</span>)cholesterol to C-20 isomeric ( sup <span class="hlt">14</span> <span class="hlt">C</span>)pregn-5-ene-3,20-diols in the tobacco hornworm, Manduca sexta</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lozano, R.; Thompson, M.J.; Svoboda, J.A.; Lusby, W.R.; Wilzer, K.R. Jr. )</p> <p>1989-03-01</p> <p>After injection into male and female fifth-instar larvae of Manduca sexta, ({sup <span class="hlt">14</span>}<span class="hlt">C</span>)cholesterol was converted to C21 steroids, ({sup <span class="hlt">14</span>}<span class="hlt">C</span>)pregn-5-ene-3 beta,20-diols. These metabolites were isolated from 8-day-old pupae and were identified by TLC, HPLC, and GC-MS as the C-20 isomers of pregnene-3 beta,20-diol. They also were isolated from male and female meconium fluid (of 16-day-old pupae) following injection of ({sup <span class="hlt">14</span>}<span class="hlt">C</span>)cholesterol into 14-day-old pupae.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/8542','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/8542"><span id="translatedtitle">A new <span class="hlt">14</span><span class="hlt">C</span> calibration data set for the last deglaciation based on marine varves</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hughen, K A; Kashgarian, M; Lehman, S J; Overpeck, J T; Peterson, L C; Southon, J R</p> <p>1999-02-22</p> <p>Varved sediments of the tropical Cariaco basin provide a new {sup <span class="hlt">14</span>}<span class="hlt">C</span> calibration data set for the period of deglaciation (10,000 to 14,500 years before present: 10-14.5 cal ka BP). Independent evaluations of the Cariasco Basin calendar and {sup <span class="hlt">14</span>}<span class="hlt">C</span> chronologies were based on the agreement of varve ages with the GISP2 ice core layer chronology for similar high-resolution paleoclimate records, in addition to {sup <span class="hlt">14</span>}<span class="hlt">C</span> age agreement with terrestrial {sup <span class="hlt">14</span>}<span class="hlt">C</span> dates, even during large climatic changes. These assessments indicate that the Cariaco Basin {sup <span class="hlt">14</span>}<span class="hlt">C</span> reservoir age remained stable throughout the Younger Dryas and late Alleroed climatic events and that the varve and {sup <span class="hlt">14</span>}<span class="hlt">C</span> chronologies provide an accurate alternative to existing calibrations based on coral U/Th dates. The Cariaco Basin calibration generally agrees with coral-derived calibrations but is more continuous and resolves century-scale details of {sup <span class="hlt">14</span>}<span class="hlt">C</span> change not seen in the coral records. {sup <span class="hlt">14</span>}<span class="hlt">C</span> plateaus can be identified at 9.6, 11.4, and 11.7 {sup <span class="hlt">14</span>}<span class="hlt">C</span> ka BP, in addition to a large, sloping plateau during the Younger Dryas ({approximately}10 to 11 {sup <span class="hlt">14</span>}<span class="hlt">C</span> ka BP). Accounting for features such as these is crucial to determining the relative timing and rates of change during abrupt global climate changes of the last deglaciation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/460041','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/460041"><span id="translatedtitle">Quaternary downcutting rate of the new river, Virginia, measured from differential decay of cosmogenic {sup <span class="hlt">26</span>}<span class="hlt">Al</span> and {sup 10}Be in cave-deposited alluvium</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Granger, D.E.; Kirchner, J.W.; Finkel, R.C.</p> <p>1997-02-01</p> <p>The concentrations of the cosmogenic radionuclides {sup <span class="hlt">26</span>}<span class="hlt">Al</span> and {sup 10}Be in quartz can be used to date sediment burial. Here we use {sup <span class="hlt">26</span>} <span class="hlt">Al</span> and {sup 10}Be in cave-deposited river sediment to infer the time of sediment emplacement. Sediment burial dates from a vertical sequence of caves along the New River constrain its Quaternary downcutting rate to 27.3{+-}4.5 m/m.y. and may provide evidence of regional tectonic tilt. 32 refs., 3 figs., 1 tab.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GeCoA.110..190M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeCoA.110..190M"><span id="translatedtitle">Heterogeneous distribution of <span class="hlt">26</span><span class="hlt">Al</span> at the birth of the Solar System: Evidence from corundum-bearing refractory inclusions in carbonaceous chondrites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Makide, Kentaro; Nagashima, Kazuhide; Krot, Alexander N.; Huss, Gary R.; Hutcheon, Ian D.; Hellebrand, Eric; Petaev, Michail I.</p> <p>2013-06-01</p> <p>We report on the mineralogy, petrology, and in situ oxygen- and magnesium-isotope measurements using secondary ion mass spectrometry of 10 corundum-bearing calcium-aluminum-rich inclusions (CAIs) from the Adelaide (ungrouped), Murray and Murchison (CM) carbonaceous chondrites. We also measured in situ oxygen-isotope compositions of several isolated corundum grains in the matrices of Murray and Murchison. Most of the corundum-bearing objects studied are uniformly 16O-rich [Δ17O values range from -17‰ to -28‰ (2σ = ±2.5‰) (Δ17Oavr = -23 ± 5‰)], suggesting that they formed in a 16O-rich gas of approximately solar composition and largely avoided subsequent thermal processing in an 16O-poor gaseous reservoir. There is a large spread of the initial <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratio [(<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0] in the corundum-bearing CAIs. Two Adelaide CAIs show no resolvable excess of radiogenic 26Mg (δ26Mg∗): the inferred (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 are (0.6 ± 2.0) × 10-6 and (-0.9 ± 1.2) × 10-6, respectively. Slopes of the model <span class="hlt">26</span><span class="hlt">Al</span>-26Mg isochrons in five CAIs from Murray and Murchison are (4.4 ± 0.2) × 10-5, (3.3 ± 0.3) × 10-5, (4.1 ± 0.3) × 10-5, (3.9 ± 0.4) × 10-5, and (4.0 ± 2.0) × 10-6, respectively. These values are lower than the canonical (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 ratio of (5.23 ± 0.13) × 10-5 inferred from the whole-rock magnesium-isotope measurements of the CV CAIs, but similar to the (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)0 ratio of (4.1 ± 0.2) × 10-5 in the corundum-bearing CAI F5 from Murray. Five other previously studied corundum-bearing CAIs from Acfer 094 (ungrouped) and CM carbonaceous chondrites showed no resolvable δ26Mg∗. We conclude that the corundum-bearing CAIs, as well as the solar corundum grains from matrices and acid-resistant residues of unequilibrated ordinary and carbonaceous chondrites, recorded heterogeneous distribution of <span class="hlt">26</span><span class="hlt">Al</span> in the Solar System during an epoch of CAI formation. The <span class="hlt">26</span><span class="hlt">Al</span>-rich and <span class="hlt">26</span><span class="hlt">Al</span>-poor corundum-bearing CAIs and solar corundum grains represent different</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMEP33D..07H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMEP33D..07H"><span id="translatedtitle">Eroding and Inflating the Atacama Desert, Chile: Insights Through Cosmogenic 10-Be, <span class="hlt">26</span>-<span class="hlt">Al</span> and 21-Ne</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Heimsath, A. M.; Jungers, M. C.; Amundson, R.; Balco, G.; Shuster, D. L.</p> <p>2010-12-01</p> <p>Enigmas of the Atacama Desert are as abundant as the hypotheses formulated to explain them. This fascinating and extreme landscape attracts scientists from disparate disciplines, spawning remarkable insights into the connections between climate, tectonics, biota and landscape evolution. Recent work explores such connections on timescales ranging from millions to thousands of years. Both the timing of the onset of hyperaridity in the Atacama and its relationship to the uplift of the Andes are especially well-debated topics. Similarly enigmatic, but less widely studied, are the connections between the timing of hyperaridity and the surface morphology of the region. Specifically, the extent, nature, and timing of formation for the extensive salars across the Atacama are undeniably linked to the climate history of the region. Adjacent to the extensive salars are landscapes that appear to be shaped by processes more typically associated with temperate landscapes: rilling and gullying, extensive terrace deposition, steep fault scarps, landslide deposits, and extensive fan and paleosurface deposits. Our primary goal in this project is to establish chronologies and rates for the surface processes driving landscape evolution for two field regions in the Atacama. To achieve this goal we are also testing and expanding upon the burial dating methodology (Balco and Shuster, 2009) that couples the stable cosmogenic nuclide, 21Ne, with the radiogenic nuclides, 10Be and <span class="hlt">26</span><span class="hlt">Al</span>. Here we present new results from remarkably different field settings from the north-central Atacama. The southern region, inland from Antofagasta, is relatively well studied to determine how the onset of hyperaridity impacted water-driven processes. The northern region, north of the Rio Loa and Calama, differs most notably by the enormous basin fills of salt (e.g. Salar de Llamara and Salar Grande) and evidence of more extensive recently active salars. Across both regions we use in 10Be, <span class="hlt">26</span><span class="hlt">Al</span>, and 21Ne to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18308434','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18308434"><span id="translatedtitle"><span class="hlt">14</span><span class="hlt">C</span> content in vegetation in the vicinities of Brazilian nuclear power reactors.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dias, Cíntia Melazo; Santos, Roberto Ventura; Stenström, Kristina; Nícoli, Iêda Gomes; Skog, Göran; da Silveira Corrêa, Rosangela</p> <p>2008-07-01</p> <p>(<span class="hlt">14</span>)<span class="hlt">C</span> specific activities were measured in grass samples collected around Brazilian nuclear power reactors. The specific activity values varied between 227 and 299 Bq/kg C. Except for two samples which showed (<span class="hlt">14</span>)<span class="hlt">C</span> specific activities 22% above background values, half of the samples showed background specific activities, and the other half had a (<span class="hlt">14</span>)<span class="hlt">C</span> excess of 1-18%. The highest specific activities were found close to the nuclear power plants and along the main wind directions (NE and NNE). The activity values were found to decrease with increasing distance from the reactors. The unexpectedly high (<span class="hlt">14</span>)<span class="hlt">C</span> excess values found in two samples were related to the local topography, which favors (<span class="hlt">14</span>)<span class="hlt">C</span> accumulation and limits the dispersion of the plume. The results indicate a clear (<span class="hlt">14</span>)<span class="hlt">C</span> anthropogenic signal within 5 km around the nuclear power plants which is most prominent along northeastwards, the prevailing wind direction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3663418','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3663418"><span id="translatedtitle">Natural Abundance <span class="hlt">14</span><span class="hlt">C</span> Content of Dibutyl Phthalate (DBP) from Three Marine Algae</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Namikoshi, Michio; Fujiwara, Takeshi; Nishikawa, Teruaki; Ukai, Kazuyo</p> <p>2006-01-01</p> <p>Analysis of the natural abundance <span class="hlt">14</span><span class="hlt">C</span> content of dibutyl phthalate (DBP) from two edible brown algae, Undaria pinnatifida and Laminaria japonica, and a green alga, Ulva sp., revealed that the DBP was naturally produced. The natural abundance <span class="hlt">14</span><span class="hlt">C</span> content of di-(2-ethylhexyl) phthalate (DEHP) obtained from the same algae was about 50–80% of the standard sample and the <span class="hlt">14</span><span class="hlt">C</span> content of the petrochemical (industrial) products of DBP and DEHP were below the detection limit.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009QSRv...28.2982H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009QSRv...28.2982H"><span id="translatedtitle">Atmospheric <span class="hlt">14</span><span class="hlt">C</span> variations derived from tree rings during the early Younger Dryas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hua, Quan; Barbetti, Mike; Fink, David; Kaiser, Klaus Felix; Friedrich, Michael; Kromer, Bernd; Levchenko, Vladimir A.; Zoppi, Ugo; Smith, Andrew M.; Bertuch, Fiona</p> <p>2009-12-01</p> <p>Atmospheric radiocarbon variations over the Younger Dryas interval, from ˜13,000 to 11,600 cal yr BP, are of immense scientific interest because they reveal crucial information about the linkages between climate, ocean circulation and the carbon cycle. However, no direct and reliable atmospheric <span class="hlt">14</span><span class="hlt">C</span> records based on tree rings for the entire Younger Dryas have been available. In this paper, we present (1) high-precision <span class="hlt">14</span><span class="hlt">C</span> measurements on the extension of absolute tree-ring chronology from 12,400 to 12,560 cal yr BP and (2) high-precision, high-resolution atmospheric <span class="hlt">14</span><span class="hlt">C</span> record derived from a 617-yr-long tree-ring chronology of Huon pine from Tasmania, Australia, spanning the early Younger Dryas. The new tree-ring <span class="hlt">14</span><span class="hlt">C</span> records bridge the current gap in European tree-ring radiocarbon chronologies during the early Younger Dryas, linking the floating Lateglacial Pine record to the absolute tree-ring timescale. A continuous and reliable atmospheric <span class="hlt">14</span><span class="hlt">C</span> record for the past 14,000 cal yr BP including the Younger Dryas is now available. The new records indicate that the abrupt rise in atmospheric Δ <span class="hlt">14</span><span class="hlt">C</span> associated with the Younger Dryas onset occurs at ˜12,760 cal yr BP, ˜240 yrs later than that recorded in Cariaco varves, with a smaller magnitude of ˜40‰ followed by several centennial Δ <span class="hlt">14</span><span class="hlt">C</span> variations of 20-25‰. Comparing the tree-ring Δ <span class="hlt">14</span><span class="hlt">C</span> to marine-derived Δ <span class="hlt">14</span><span class="hlt">C</span> and modelled Δ <span class="hlt">14</span><span class="hlt">C</span> based on ice-core 10Be fluxes, we conclude that changes in ocean circulation were mainly responsible for the Younger Dryas onset, while a combination of changes in ocean circulation and <span class="hlt">14</span><span class="hlt">C</span> production rate were responsible for atmospheric Δ <span class="hlt">14</span><span class="hlt">C</span> variations for the remainder of the Younger Dryas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17399945','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17399945"><span id="translatedtitle">Distribution of <span class="hlt">14</span><span class="hlt">C</span>-atrazine following an acute lactational exposure in the Wistar rat.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Stoker, Tammy E; Cooper, Ralph L</p> <p>2007-06-01</p> <p>The purpose of the present study was to examine the distribution of atrazine in the lactating dam and suckling neonate following an acute exposure to either 2 or 4mg/kg <span class="hlt">14</span><span class="hlt">C</span>-atrazine (<span class="hlt">14</span><span class="hlt">C</span>-ATR) by gavage. <span class="hlt">14</span><span class="hlt">C</span>-ATR was administered to the nursing dam on postnatal day 3 by oral gavage. Two and a half hours after exposure of the mother to <span class="hlt">14</span><span class="hlt">C</span>-ATR, the pups were allowed to nurse for 30min. At the end of the nursing period, radiolabelled residues of <span class="hlt">14</span><span class="hlt">C</span>-ATR [or <span class="hlt">14</span><span class="hlt">C</span>-chlorotriazines (<span class="hlt">14</span><span class="hlt">C</span>-ClTRI)] were measured in the organs and tissues of the perfused dam and in the stomachs and brains of the rat pups. Both the 2 and the 4mg atrazine treatments resulted in a transfer of approximately 0.007% of <span class="hlt">14</span><span class="hlt">C</span>-ClTRI to the stomach (indicator of milk content) and 0.0002% to the brains of the offspring following the 30-min nursing period. Three hours following the dose of <span class="hlt">14</span><span class="hlt">C</span>-ATR, there was a distribution of <span class="hlt">14</span><span class="hlt">C</span>-ClTRI to the organs of the dam, with the highest amounts in the liver and kidney (1.1 and 0.3% of the administered dose, respectively). Approximately 0.003% of the administered dose was present in three different brain sections of the dam following both doses of <span class="hlt">14</span><span class="hlt">C</span>-ATR. The results of this study demonstrate that <span class="hlt">14</span><span class="hlt">C</span>-ClTRI are present in small concentrations in the brain and tissues of the dam (adult female) and provide evidence that atrazine or the metabolites can have direct effects on neuroendrocrine function. The results also provide information for postnatal distribution into the suckling neonate during early lactation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6924609','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6924609"><span id="translatedtitle">(/sup <span class="hlt">14</span>/<span class="hlt">C</span>)chloroacetylcholine as an advantageous affinity label of the acetylcholine receptor</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bodmer, D.M.; Sin-Ren, A.C.; Waser, P.G.</p> <p>1987-01-01</p> <p>The alkylating agent (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)chloroacetylcholine perchlorate ((/sup <span class="hlt">14</span>/<span class="hlt">C</span>) ClACh) was synthesized and used for affinity labelling of the nicotinic acetylcholine receptor from Torpedo marmorata. Solubilized and affinity-purified receptor proteins were reduced and alkylated according to the bromoacetylcholine-method. Covalent binding of (/sup <span class="hlt">14</span>/<span class="hlt">C</span>) ClACh to the cholinergic receptor proved to be specific and saturable, and occurred exclusively to the alpha-subunit. Halogen substitution of acetylcholine by chlorine and insertion of a /sup <span class="hlt">14</span>/<span class="hlt">C</span>-isotope instead of the widely used /sup 3/H resulted in favorable properties of the affinity label.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1702876','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1702876"><span id="translatedtitle">Metabolism of small multiple doses of (<span class="hlt">14</span><span class="hlt">C</span>) nicotine in the cat</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Turner, D. M.</p> <p>1971-01-01</p> <p>1. The distribution and metabolism of (2′-<span class="hlt">14</span><span class="hlt">C</span>) nicotine given as a series of small intravenous injections (4 μg/kg every 60 s for 20 min) have been studied in the cat. 2. Blood concentrations of (<span class="hlt">14</span><span class="hlt">C</span>) nicotine reached a maximum of 100 ng/ml at 20 min whereas blood concentrations of cotinine were maximal shortly afterwards. 3. The maximum concentration of nicotine in the blood was greater than that obtained by giving the same total dose as a continuous infusion ((4 μg/kg)/min for 20 min). 4. Urinary excretion accounted for 90% of the total multiple dose in 72 hours. After 24 h, however, only 2·5% of the radioactivity as (<span class="hlt">14</span><span class="hlt">C</span>) nicotine and 0·05% as (<span class="hlt">14</span><span class="hlt">C</span>) cotinine was excreted. 5. Gastric juice after 2 h contained significant amounts of activity which was almost entirely composed of (<span class="hlt">14</span><span class="hlt">C</span>) nicotine and (<span class="hlt">14</span><span class="hlt">C</span>) cotinine. 6. There were significant regional differences in the concentration of (<span class="hlt">14</span><span class="hlt">C</span>) nicotine in the brain; amounts were greatest in cerebral hemispheres and smallest in the spinal cord. The hypothalamus and thalamus contained significantly higher concentrations of (<span class="hlt">14</span><span class="hlt">C</span>) nicotine than the whole mid brain. (<span class="hlt">14</span><span class="hlt">C</span>) Cotinine concentrations were highest in the cerebellum. PMID:5576257</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..1214299R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..1214299R"><span id="translatedtitle">Using 10Be records to identify possible <span class="hlt">14</span><span class="hlt">C</span> calibration uncertainties during the Holocene</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Raimund, Muscheler</p> <p>2010-05-01</p> <p>The Intcal04 and Intcal09 radiocarbon calibration records are based on multiple tree-ring <span class="hlt">14</span><span class="hlt">C</span> data sets for Holocene period (Reimer et al. 2004, Reimer et al. 2009). While the dendrochronolgical dating of the trees is supposedly free of errors there are differences between various <span class="hlt">14</span><span class="hlt">C</span> data sets that underlie the <span class="hlt">14</span><span class="hlt">C</span> calibration curve. Due to lack of knowledge about the reasons for the differences the Intcal04/09 calibration curves provide a smoothed average of the underlying <span class="hlt">14</span><span class="hlt">C</span> records. Therefore, problems in one or several of the underlying <span class="hlt">14</span><span class="hlt">C</span> records would translate directly into errors in the <span class="hlt">14</span><span class="hlt">C</span> age calibration. Additional knowledge about expected variations in the <span class="hlt">14</span><span class="hlt">C</span> production rate could help to improve the calibration record since it would allow us to assess how well the different <span class="hlt">14</span><span class="hlt">C</span> records represent the atmospheric <span class="hlt">14</span><span class="hlt">C</span> concentration. I propose that 10Be records could be used as additional criteria to chose which of the published <span class="hlt">14</span><span class="hlt">C</span> records should be preferred (or given stronger weight) for the construction of the calibration curve. Alternatively, 10Be records could point to periods where <span class="hlt">14</span><span class="hlt">C</span> data should be re-measured in order to improve the calibration curve. I will show for some case studies that the 10Be records from the Greenland ice cores (Muscheler et al. 2004, Vonmoos et al. 2006) indeed provide useful information to scrutinise the Intcal04/09 calibration curve, which could help to improve the <span class="hlt">14</span><span class="hlt">C</span> calibration curve during the Holocene. Especially shorter-term changes are strongly dampened in the Intcal04/09 calibration record. However, 10Be and some <span class="hlt">14</span><span class="hlt">C</span> records do exhibit more variability as compared to the calibration record. Therefore, the combined 10Be/<span class="hlt">14</span><span class="hlt">C</span> approach could add confidence that these should be reflected in the <span class="hlt">14</span><span class="hlt">C</span> calibration record. References: Muscheler, R., Beer, J. et al., 2004. Changes in the carbon cycle during the last deglaciation as indicated by the comparison of 10Be and <span class="hlt">14</span><span class="hlt">C</span> records. Earth and Planetary Science Letters</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70094758','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70094758"><span id="translatedtitle">Rates of sediment supply to arroyos from upland erosion determined using in situ produced cosmogenic 10Be and <span class="hlt">26</span><span class="hlt">Al</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Clapp, Erik M.; Bierman, Paul R.; Nichols, Kyle K.; Pavich, Milan; Caffee, Marc A.</p> <p>2001-01-01</p> <p>Using 10Be and <span class="hlt">26</span><span class="hlt">Al</span> measured in sediment and bedrock, we quantify rates of upland erosion and sediment supply to a small basin in northwestern New Mexico. This and many other similar basins in the southwestern United States have been affected by cycles of arroyo incision and backfilling several times in the past few millennia. The sediment generation (275 ± 65 g m−2 yr−1) and bedrock equivalent lowering rates (102 ± 24 m myr−1) we determine are sufficient to support at least three arroyo cycles in the past 3,000 years, consistent with rates calculated from a physical sediment budget within the basin and regional rates determined using other techniques. Nuclide concentrations measured in different sediment sources and reservoirs suggest that the arroyo is a good spatial and temporal integrator of sediment and associated nuclide concentrations from throughout the basin, that the basin is in steady-state, and that nuclide concentration is independent of sediment grain size. Differences between nuclide concentrations measured in sediment sources and reservoirs reflect sediment residence times and indicate that subcolluvial bedrock weathering on hillslopes supplies more sediment to the basin than erosion of exposed bedrock.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JPhG...39j5201D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JPhG...39j5201D"><span id="translatedtitle">44Ti, <span class="hlt">26</span><span class="hlt">Al</span> and 53Mn samples for nuclear astrophysics: the needs, the possibilities and the sources</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dressler, R.; Ayranov, M.; Bemmerer, D.; Bunka, M.; Dai, Y.; Lederer, C.; Fallis, J.; StJ Murphy, A.; Pignatari, M.; Schumann, D.; Stora, T.; Stowasser, T.; Thielemann, F.-K.; Woods, P. J.</p> <p>2012-10-01</p> <p>Exploration of the physics involved in the production of cosmogenic radionuclides requires experiments using the same rare, radioactive nuclei in sufficient quantities. For this work, such exotic radionuclides have been extracted from previously proton-irradiated stainless steel samples using wet chemistry separation techniques. The irradiated construction material has arisen from an extended material research programme at the Paul Scherrer Institute, called STIP (SINQ Target Irradiation Program), where several thousand samples of different materials were irradiated with protons and neutrons of energies up to 570 MeV. In total, 8 × 1017 atoms of 44Ti, ˜1016 atoms of <span class="hlt">26</span><span class="hlt">Al</span> and ˜1019 atoms of 53Mn are available from selected samples. These materials may now be used to produce targets or radioactive beams for nuclear reaction studies with protons, neutrons and α-particles. The work is part of the ERAWAST initiative (Exotic Radionuclides from Accelerator Waste for Science and Technology), aimed at facilitating new collaborations between the isotope producers and users from different scientific fields including nuclear astrophysics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/13065','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/13065"><span id="translatedtitle">Mannosyltransferase activity in calf pancreas microsomes. Formation of <span class="hlt">14</span><span class="hlt">C</span>-labeled lipid-linked oligosaccharides from GDP-D-[<span class="hlt">14</span><span class="hlt">C</span>]mannose and pancreatic dolichyl beta-D-[<span class="hlt">14</span><span class="hlt">C</span>]mannopyranosyl phosphate.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Herscovics, A; Golovtchenko, A M; Warren, C D; Bugge, B; Jeanloz, R W</p> <p>1977-01-10</p> <p>Calf pancreas microsomes incorporated radioactive D-mannose from GDP-D-[<span class="hlt">14</span><span class="hlt">C</span>]mannose into lipid-bound oligosaccharides extracted with chloroform/methanol/water (10/10/2.5, v/v). Several products, which probably differed in the size of the oligosaccharide moiety, were labeled. These could be partially resolved by thin layer chromatography and DEAE-cellulose chromatography. The labeled lipid-bound oligosaccharides were retained on DEAE-cellulose more strongly than synthetic dolichyl alpha-D-[<span class="hlt">14</span><span class="hlt">C</span>]mannopyranosyl phosphate. They were stable to mild alkali, but labile to acid and hot alkali. Acid treatment yielded a neutral <span class="hlt">14</span><span class="hlt">C</span>-labeled oligosaccharide fraction which was estimated by gel filtration to have a minimum of 8 monosaccharide residues. Hot alkali treatment yielded a mixture of neutral and acidic <span class="hlt">14</span><span class="hlt">C</span>-labeled oligosaccharides which could be transformed into neutral products by alkaline phosphatase. The D-[<span class="hlt">14</span><span class="hlt">C</span>]mannose residues were alpha-linked at the nonreducing terminus of the oligosaccharides since they could be removed completely with alpha-mannosidase. Most of the D-[<span class="hlt">14</span><span class="hlt">C</span>]mannose-labeled oligosaccharides were retained on concanavalin A Sepharose and eluted with methyl alpha-D-mannopyranoside. Pancreatic dolichyl beta-D-[<span class="hlt">14</span><span class="hlt">C</span>]mannopyranosyl phosphate incubated with calf pancreas microsomes in the presence of sodium taurocholate was efficiently utilized as donor of alpha-D-mannosyl residues in lipid-bound oligosaccharides. The products formed from dolichyl beta-D-[<span class="hlt">14</span><span class="hlt">C</span>]mannopyranosyl phosphate were identical with those formed from GDP-D-[<span class="hlt">14</span><span class="hlt">C</span>]mannose, and evidence was obtained to show that the dolichyl beta-D-[<span class="hlt">14</span><span class="hlt">C</span>]mannopyranosyl phosphate was serving as donor without prior conversion to GDP-D-[<span class="hlt">14</span><span class="hlt">C</span>]mannose. Transfer of mannose from dolichyl beta-D-[<span class="hlt">14</span><span class="hlt">C</span>]mannopyranosyl phosphate to lipid-bound oligosaccharides took place at a pH optimum of 7.3, whereas transfer to the precipitate containing glycoproteins was greatest at pH 6.0 in Tris/maleate buffer. The addition of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011E%26PSL.310...65S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011E%26PSL.310...65S"><span id="translatedtitle">No evidence for a deglacial intermediate water Δ <span class="hlt">14</span><span class="hlt">C</span> anomaly in the SW Atlantic</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sortor, Rachel N.; Lund, David C.</p> <p>2011-10-01</p> <p>The last deglaciation was characterized by an increase in atmospheric pCO 2 and decrease in atmospheric radiocarbon activity. One hypothesis is that these changes were due to out-gassing of <span class="hlt">14</span><span class="hlt">C</span>-depleted carbon from the abyssal ocean. Reconstructions of foraminiferal Δ <span class="hlt">14</span><span class="hlt">C</span> from the eastern tropical Pacific, Arabian Sea, and high latitude North Atlantic show that severe depletions in <span class="hlt">14</span><span class="hlt">C</span> occurred at intermediate water depths during the last deglaciation. It has been suggested that <span class="hlt">14</span><span class="hlt">C</span>-depleted water from the abyss upwelled in the Southern Ocean and was then carried by Antarctic Intermediate Water (AAIW) to these sites. However, locations in the South Pacific in the direct path of modern-day AAIW do not exhibit the Δ <span class="hlt">14</span><span class="hlt">C</span> excursion and therefore cast doubt upon the AAIW mechanism ( De Pol-Holz et al., 2010; Rose et al., 2010). Here we evaluate whether or not a deglacial <span class="hlt">14</span><span class="hlt">C</span> anomaly occurred at intermediate depths in the Southwest Atlantic. We find that the deglacial benthic Δ <span class="hlt">14</span><span class="hlt">C</span> trend at our site is similar to the atmospheric Δ <span class="hlt">14</span><span class="hlt">C</span> trend. Our results are also largely consistent with results from U/Th-dated corals at shallower water depths on the Brazil Margin (Mangini et al., 2010). We find no evidence in the southwestern Atlantic of a ~ 300‰ decrease in intermediate water Δ <span class="hlt">14</span><span class="hlt">C</span> from 18 to 14 kyr BP like that observed in the eastern tropical Pacific ( Marchitto et al., 2007). When our results are paired with those from the South Pacific, it appears AAIW did not carry a highly <span class="hlt">14</span><span class="hlt">C</span>-depleted signal during the deglaciation. Another source of carbon is apparently required to explain the intermediate-depth Δ <span class="hlt">14</span><span class="hlt">C</span> anomalies in the North Atlantic, Indian, and Pacific Oceans.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PalOc..31.1030B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PalOc..31.1030B"><span id="translatedtitle">Refined modeling and <span class="hlt">14</span><span class="hlt">C</span> plateau tuning reveal consistent patterns of glacial and deglacial <span class="hlt">14</span><span class="hlt">C</span> reservoir ages of surface waters in low-latitude Atlantic</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Balmer, Sven; Sarnthein, Michael; Mudelsee, Manfred; Grootes, Pieter M.</p> <p>2016-08-01</p> <p>Modeling studies predict that changes in radiocarbon (<span class="hlt">14</span><span class="hlt">C</span>) reservoir ages of surface waters during the last deglacial episode will reflect changes in both atmospheric <span class="hlt">14</span><span class="hlt">C</span> concentration and ocean circulation including the Atlantic Meridional Overturning Circulation. Tests of these models require the availability of accurate <span class="hlt">14</span><span class="hlt">C</span> reservoir ages in well-dated late Quaternary time series. We here test two models using plateau-tuned <span class="hlt">14</span><span class="hlt">C</span> time series in multiple well-placed sediment core age-depth sequences throughout the lower latitudes of the Atlantic Ocean. <span class="hlt">14</span><span class="hlt">C</span> age plateau tuning in glacial and deglacial sequences provides accurate calendar year ages that differ by as much as 500-2500 years from those based on assumed global reservoir ages around 400 years. This study demonstrates increases in local Atlantic surface reservoir ages of up to 1000 years during the Last Glacial Maximum, ages that reflect stronger trades off Benguela and summer winds off southern Brazil. By contrast, surface water reservoir ages remained close to zero in the Cariaco Basin in the southern Caribbean due to lagoon-style isolation and persistently strong atmospheric CO2 exchange. Later, during the early deglacial (16 ka) reservoir ages decreased to a minimum of 170-420 <span class="hlt">14</span><span class="hlt">C</span> years throughout the South Atlantic, likely in response to the rapid rise in atmospheric pCO2 and Antarctic temperatures occurring then. Changes in magnitude and geographic distribution of <span class="hlt">14</span><span class="hlt">C</span> reservoir ages of peak glacial and deglacial surface waters deviate from the results of Franke et al. (2008) but are generally consistent with those of the more advanced ocean circulation model of Butzin et al. (2012).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21254838','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21254838"><span id="translatedtitle">Dilute Nuclear States: {sup 12}C, {sup 10}Be and {sup <span class="hlt">14</span>}<span class="hlt">C</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Freer, M.</p> <p>2008-11-11</p> <p>The experimental evidence for dilute {alpha}-particle states in {sup 12}C, {sup 10}Be and {sup <span class="hlt">14</span>}<span class="hlt">C</span> is discussed. The question of the location of the 2{sup +} excitation of the 7.65 MeV {sup 12}C state remains unresolved, as does the existence of possible analogue states in {sup <span class="hlt">14</span>}<span class="hlt">C</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5320593','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5320593"><span id="translatedtitle">Disposition of /sup <span class="hlt">14</span>/<span class="hlt">C</span> tolrestat in laboratory animals and man</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ferdinandi, E.S.; Hicks, D.R.; Cayen, M.N.</p> <p>1986-03-01</p> <p>The disposition of the aldose reductase inhibitor tolrestat (T) was determined in the mouse, rat, dog, assemensis monkey, and man. Serum T and radioactivity ratios, and % of dose excreted after p.o. administration of /sup <span class="hlt">14</span>/<span class="hlt">C</span>-T at a dose of 10 mk/kg (100 mg to man), are presented. Except for the rat and monkey, 55 to 95% of the urinary /sup <span class="hlt">14</span>/<span class="hlt">C</span> was due to T and oxo-tolrestat (oxo-T, N-((5-(trifluoromethyl)-6-methoxy-1-napthalenyl)oxo-methyl)-N-methylglycine). Oxo-T is formed, in part, non-enzymatically from T; a potential intermediate in this transformation was detected in all the urine samples. In man and monkey, about 15% and 68%, respectively, of the urinary /sup <span class="hlt">14</span>/<span class="hlt">C</span> was due to T-glucuronide. In rat urine, >90% of the /sup <span class="hlt">14</span>/<span class="hlt">C</span> was due to polar metabolites; in bile, about 66% of the /sup <span class="hlt">14</span>/<span class="hlt">C</span> was due to T. The composition of the serum /sup <span class="hlt">14</span>/<span class="hlt">C</span> in the mouse and rat was determined. In conclusion, /sup <span class="hlt">14</span>/<span class="hlt">C</span>-T was rapidly and well absorbed by all species. Except for the rat and dog, urine was the main excretion route for /sup <span class="hlt">14</span>/<span class="hlt">C</span>. Urine/sup 14/ comprised mainly T, t-glucuronide of oxo-T in all the species except the rat.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23772889','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23772889"><span id="translatedtitle">Soil metabolism of [<span class="hlt">14</span><span class="hlt">C</span>]methiozolin under aerobic and anaerobic flooded conditions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hwang, Ki-Hwan; Lim, Jong-Soo; Kim, Sung-Hun; Chang, Hee-Ra; Kim, Kyun; Koo, Suk-Jin; Kim, Jeong-Han</p> <p>2013-07-17</p> <p>Methiozolin is a new turf herbicide controlling annual bluegrass in various cool- and warm-season turfgrasses. This study was conducted to investigate the fate of methiozolin in soil under aerobic and anaerobic flooded conditions using two radiolabeled tracers, [benzyl-(<span class="hlt">14</span>)<span class="hlt">C</span>]- and [isoxazole-(<span class="hlt">14</span>)<span class="hlt">C</span>]methiozolin. The mass balance of applied radioactivity ranged from 91.7 to 104.5% in both soil conditions. In the soil under the aerobic condition, [(<span class="hlt">14</span>)<span class="hlt">C</span>]methiozolin degraded with time to remain by 17.9 and 15.9% of the applied in soil at 120 days after treatment (DAT). [(<span class="hlt">14</span>)<span class="hlt">C</span>]Carbon dioxide and the nonextractable radioactivity increased as the soil aged to reach up to 41.5 and 35.7% for [benzyl-(<span class="hlt">14</span>)<span class="hlt">C</span>]methiozolin at 120 DAT, respectively, but 36.1 and 39.8% for [isoxazole-(<span class="hlt">14</span>)<span class="hlt">C</span>]methiozolin, respectively, during the same period. The nonextractable residue was associated more with humin and fulvic acid fractions under the aerobic condition. No significant volatile products or metabolites were detected during this study. The half-life of [(<span class="hlt">14</span>)<span class="hlt">C</span>]methiozolin was approximately 49 days in the soil under the aerobic condition; however, it could not be estimated in the soil under the anaerobic flooded condition because [(<span class="hlt">14</span>)<span class="hlt">C</span>]methiozolin degradation was limited. On the basis of these results, methiozolin is considered to undergo fast degradation by aerobic microbes, but not by anaerobic microbes in soil. PMID:23772889</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=182337','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=182337"><span id="translatedtitle">Production of [<span class="hlt">14</span><span class="hlt">C</span>]fumonisin B1 by Fusarium moniliforme MRC 826 in corn cultures.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Alberts, J F; Gelderblom, W C; Vleggaar, R; Marasas, W F; Rheeder, J P</p> <p>1993-01-01</p> <p>Kinetics of growth and fumonisin production by Fusarium moniliforme MRC 826 in corn "patty" cultures were investigated, and a technique was developed for the production of [<span class="hlt">14</span><span class="hlt">C</span>]fumonisin B1 ([<span class="hlt">14</span><span class="hlt">C</span>]FB1) by using L-[methyl-<span class="hlt">14</span><span class="hlt">C</span>]methionine as the precursor. A significant (P < 0.01) correlation exists between fungal growth and FB1 (r = 0.89) and FB2 (r = 0.87) production in corn patties, beginning after 2 days and reaching the stationary phase after 14 days of incubation. [<span class="hlt">14</span><span class="hlt">C</span>]FB1 was produced by adding L-[methyl-<span class="hlt">14</span><span class="hlt">C</span>]methionine daily to cultures during the logarithmic phase of production. Incorporation of the isotope occurred at C-21 and C-22 of the fumonism molecule and was enhanced in the presence of unlabeled L-methionine. Although the concentration of exogenous unlabeled methionine is critical for incorporation of the <span class="hlt">14</span><span class="hlt">C</span> label, optimum incorporation was achieved by adding 50 mg of unlabeled L-methionine and 200 mu Ci of L-[methyl-<span class="hlt">14</span><span class="hlt">C</span>]methionine to a corn patty (30 g) over a period of 9 days, yielding [<span class="hlt">14</span><span class="hlt">C</span>]FB1 with a specific activity of 36 mu Ci/mmol. PMID:8368853</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23772889','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23772889"><span id="translatedtitle">Soil metabolism of [<span class="hlt">14</span><span class="hlt">C</span>]methiozolin under aerobic and anaerobic flooded conditions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hwang, Ki-Hwan; Lim, Jong-Soo; Kim, Sung-Hun; Chang, Hee-Ra; Kim, Kyun; Koo, Suk-Jin; Kim, Jeong-Han</p> <p>2013-07-17</p> <p>Methiozolin is a new turf herbicide controlling annual bluegrass in various cool- and warm-season turfgrasses. This study was conducted to investigate the fate of methiozolin in soil under aerobic and anaerobic flooded conditions using two radiolabeled tracers, [benzyl-(<span class="hlt">14</span>)<span class="hlt">C</span>]- and [isoxazole-(<span class="hlt">14</span>)<span class="hlt">C</span>]methiozolin. The mass balance of applied radioactivity ranged from 91.7 to 104.5% in both soil conditions. In the soil under the aerobic condition, [(<span class="hlt">14</span>)<span class="hlt">C</span>]methiozolin degraded with time to remain by 17.9 and 15.9% of the applied in soil at 120 days after treatment (DAT). [(<span class="hlt">14</span>)<span class="hlt">C</span>]Carbon dioxide and the nonextractable radioactivity increased as the soil aged to reach up to 41.5 and 35.7% for [benzyl-(<span class="hlt">14</span>)<span class="hlt">C</span>]methiozolin at 120 DAT, respectively, but 36.1 and 39.8% for [isoxazole-(<span class="hlt">14</span>)<span class="hlt">C</span>]methiozolin, respectively, during the same period. The nonextractable residue was associated more with humin and fulvic acid fractions under the aerobic condition. No significant volatile products or metabolites were detected during this study. The half-life of [(<span class="hlt">14</span>)<span class="hlt">C</span>]methiozolin was approximately 49 days in the soil under the aerobic condition; however, it could not be estimated in the soil under the anaerobic flooded condition because [(<span class="hlt">14</span>)<span class="hlt">C</span>]methiozolin degradation was limited. On the basis of these results, methiozolin is considered to undergo fast degradation by aerobic microbes, but not by anaerobic microbes in soil.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/1501596','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/1501596"><span id="translatedtitle">Bacterial uptake of <span class="hlt">14</span><span class="hlt">C</span>-chlorhexidine diacetate and <span class="hlt">14</span><span class="hlt">C</span>-benzyl alcohol and the influence of phenoxyethanol and azolectin: studies with gram-negative bacteria.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fitzgerald, K A; Davies, A; Russell, A D</p> <p>1992-01-01</p> <p>The uptake of <span class="hlt">14</span><span class="hlt">C</span>-chlorhexidine (<span class="hlt">14</span><span class="hlt">C</span>-CHA) by Pseudomonas aeruginosa and smooth, rough and deep rough strains of Escherichia coli was very rapid with maximum uptake occurring within 20 s. Despite the rapid binding, the lethal action of CHA, although concentration-dependent, is comparatively slow and occurs in minutes rather than seconds. This indicates that the initial rapid binding is followed by a second slower action, responsible for the lethal effects of CHA. The lethal action could be accelerated, particularly at modest concentrations of CHA, by the simultaneous presence of phenoxyethanol (POE) or benzyl alcohol (BZA), although the magnitude of the effect was small. Both alcohols had little effect on the binding of <span class="hlt">14</span><span class="hlt">C</span>-CHA, which does not explain the enhanced bactericidal action of CHA. Uptake of <span class="hlt">14</span><span class="hlt">C</span>-benzyl alcohol (<span class="hlt">14</span><span class="hlt">C</span>-BZA) by the same strains showed very different patterns with slower and time-related binding. CHA had a marked effect on BZA absorption but no direct link was established between binding patterns and cell death. The CHA neutraliser, azolectin, removed bound CHA (in the presence or absence of POE) very efficiently even at contact times of only 20 s.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6880284','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6880284"><span id="translatedtitle">Will there be a <span class="hlt">14</span><span class="hlt">C</span> minimum in the tropical Pacific in the 1990s</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Toggweiler, J.R. )</p> <p>1990-01-09</p> <p><span class="hlt">14</span><span class="hlt">C</span> distributions measured during GEOSECS showed large minima in bomb <span class="hlt">14</span><span class="hlt">C</span> levels in the tropical belts of the major ocean basins. Broecker et al. (1978, JGR, 83) attributed the minima to upwelling of deep water which was free of bomb <span class="hlt">14</span><span class="hlt">C</span>. Wyrtki (1981, JPO, 11) countered that heat budgets constrain the water upwelling the the equator to be from the upper themocline. Druffel (1987, JMR, 45) built a model of the Pacific upwelling system incorporating Wyrtki's description of the upwelling system. Druffel showed that the GEOSECS <span class="hlt">14</span><span class="hlt">C</span> minimum could be reproduced with upwelled upper thermocline water because bomb <span class="hlt">14</span><span class="hlt">C</span> levels were still relatively low in the tropical thermocline at the time of GEOSECS. Druffel went on to predict that mid latitude and tropical surface <span class="hlt">14</span><span class="hlt">C</span> levels would approach a common value before the 1990s and upper thermocline water masses acquired more bomb <span class="hlt">14</span><span class="hlt">C</span> and atmospheric <span class="hlt">14</span><span class="hlt">C</span> levels declined. By studying pre-bomb coral <span class="hlt">14</span><span class="hlt">C</span> records and a model simulation in Toggweiler et al. (1989, JGR, 94), I have found confirmation that some older and colder water upwells in the tropical Pacific. Upper thermocline (22-24C) water has about the same pre-bomb <span class="hlt">14</span><span class="hlt">C</span> content as pre-bomb surface waters and cannot generate a low <span class="hlt">14</span><span class="hlt">C</span> singal prior to the bomb test. The appearance of the oldest upwelled water in the coral data is correlated in time with the cold phase of the ENSO cycle. Most of the low <span class="hlt">14</span><span class="hlt">C</span> water moves southward into the South Pacific. I will argue that intensified upwelling during the cold phase of ENSO pulls up 12-<span class="hlt">14</span><span class="hlt">C</span> water from the lower layers of the Equatorial Undercurrent. Upwelling from this layer may represent an important closure mechanism for mode waters formed in the subantarctic. A source of older water makes it certain that the tropical <span class="hlt">14</span><span class="hlt">C</span> minimum will persist through the 1990s and the remainder of the post-bomb era.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/4035672','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/4035672"><span id="translatedtitle">Disposition and metabolism of 2,3-[<span class="hlt">14</span><span class="hlt">C</span>]dichloropropene in rats after inhalation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bond, J A; Medinsky, M A; Dutcher, J S; Henderson, R F; Cheng, Y S; Mewhinney, J A; Birnbaum, L S</p> <p>1985-03-30</p> <p>2,3-Dichloropropene (2,3-DCP) is a constituent of some commercially available preplant soil fumigants for the control of plant parasitic nematodes. Human exposure potential exists during manufacture of the chemicals or during bulk handling activities. The purpose of this investigation was to determine the disposition and metabolism of 2,3-[<span class="hlt">14</span><span class="hlt">C</span>]DCP in rats after inhalation. Male Fischer-344 rats were exposed nose-only to a vapor concentration of 250 nmol 2,3-[<span class="hlt">14</span><span class="hlt">C</span>]DCP/liter air (7.5 ppm; 25 degrees C, 620 Torr) for 6 hr. Blood samples were taken during exposure, and urine, feces, expired air, and tissues were collected for up to 65 hr after exposure. Urinary excretion was the major route of elimination of <span class="hlt">14</span><span class="hlt">C</span> (55% of estimated absorbed 2,3-DCP). Half-time for elimination of <span class="hlt">14</span><span class="hlt">C</span> in urine was 9.8 +/- 0.05 hr (means +/- SE). Half-time for elimination of <span class="hlt">14</span><span class="hlt">C</span> feces (17% of absorbed 2,3-DCP) was 12.9 +/- 0.14 hr (means +/- SE). Approximately 1 and 3% of the estimated absorbed 2,3-[<span class="hlt">14</span><span class="hlt">C</span>]DCP were exhaled as either 2,3-[<span class="hlt">14</span><span class="hlt">C</span>]DCP or 14CO2, respectively. Concentrations of <span class="hlt">14</span><span class="hlt">C</span> in blood increased during 240 min of exposure, after which no further increases in blood concentration of <span class="hlt">14</span><span class="hlt">C</span> were seen. <span class="hlt">14</span><span class="hlt">C</span> was widely distributed in tissues analyzed after a 6-hr exposure of rats to 2,3-[<span class="hlt">14</span><span class="hlt">C</span>]DCP. Urinary bladder (150 nmol/g), nasal turbinates (125 nmol/g), kidneys (84 nmol/g), small intestine (61 nmol/g), and liver (35 nmol/g) were tissues with the highest concentrations of <span class="hlt">14</span><span class="hlt">C</span> immediately after exposure. Over 90% of the <span class="hlt">14</span><span class="hlt">C</span> in tissues analyzed was 2,3-DCP metabolites. Half-times for elimination of <span class="hlt">14</span><span class="hlt">C</span> from tissues examined ranged from 3 to 11 hr. The data from this study indicate that after inhalation 2,3-DCP is metabolized in tissues and readily excreted.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.V31G..09C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V31G..09C"><span id="translatedtitle">The Gas-Filled-Magnet at PRIME Lab: Increased Sensitivity of Cosmogenic Nuclide Measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Caffee, M. W.; Granger, D. E.; Woodruff, T. E.</p> <p>2015-12-01</p> <p>Abstract: Using accelerator mass spectrometry (AMS), radionuclides produced either by cosmic-ray interactions or by nucleogenic means can be measured. Typical isotopic abundance ratios range from 1 x 10-10 to 1 x 10-15. The routinely measured radionuclides are 10Be, <span class="hlt">14</span><span class="hlt">C</span>, <span class="hlt">26</span><span class="hlt">Al</span>, <span class="hlt">36</span><span class="hlt">Cl</span>, and 129I. Be-10, <span class="hlt">26</span><span class="hlt">Al</span>, and <span class="hlt">36</span><span class="hlt">Cl</span> have isobaric interferences that cannot be eliminated mass through mass analysis, but dE/dx techniques suppresses these isobars enough to allow successful measurements. There are compromises, the isobar for <span class="hlt">26</span><span class="hlt">Al</span>, 26Mg, precludes successful measurement of <span class="hlt">26</span><span class="hlt">Al</span> if AlO- is injected into the accelerator. Mg- doesn't form a stable negative ion so a <span class="hlt">26</span><span class="hlt">Al</span> measurement requires injection of <span class="hlt">26</span><span class="hlt">Al</span>-. But the Al- ion is formed inefficiently; secondary ion currents using Al- are ~ 10 times less than an AlO- secondary ion beam. Precision scales with count rate so precise measurement of the <span class="hlt">26</span><span class="hlt">Al</span>/Al for all but higher ratio samples is difficult. It has long been recognized that a gas-filled-magnet (GFM) could potentially improve the measurement of those radionuclides with intractable isobar interferences. A GFM works on the principle that each element of an isobar pair, e.g. 26Mg and <span class="hlt">26</span><span class="hlt">Al</span>, has a different average charge state as it traverses a gas (3-4 Torr of N2) contained within the vacuum jacket of a magnet. The magnet steers each species with its own momentum-to-charge ratio on its own distinct radius of curvature. The magnet can be tuned to allow the isotope of interest into a dE/dx detector; most of the isobar doesn't make it into the detector. Using the PRIME Lab GFM we are now able to routinely run <span class="hlt">26</span><span class="hlt">Al</span> with a precision that is comparable to that obtained with 10Be. We are also using the GFM for routine measurements of 10Be and <span class="hlt">36</span><span class="hlt">Cl</span>. Although the improvement for these nuclides is not as pronounced as it is for <span class="hlt">26</span><span class="hlt">Al</span>, the GFM has improved the detection sensitivity for both. Our 10Be background is now ~ 5 x 10-16 and for <span class="hlt">36</span><span class="hlt">Cl</span> we can now run the source more</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24975487','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24975487"><span id="translatedtitle">Root and foliar uptake, translocation, and distribution of [<span class="hlt">14</span><span class="hlt">C</span>] fluoranthene in pea plants (Pisum sativum).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zezulka, Stěpán; Klemš, Marek; Kummerová, Marie</p> <p>2014-10-01</p> <p>Uptake of (<span class="hlt">14</span>)<span class="hlt">C</span>-labeled fluoranthene ([(<span class="hlt">14</span>)<span class="hlt">C</span>]FLT) via both roots and leaves of Pisum sativum seedlings and distribution of [(<span class="hlt">14</span>) <span class="hlt">C</span>] in plants by both acropetal and basipetal transport was evaluated. The highest [(<span class="hlt">14</span>)<span class="hlt">C</span>] level was found in the root base (≈270 × 10(4) dpm/g dry wt) and the lowest level in the stem apex (<2 × 10(4) dpm/g dry wt) after just 2 h of root exposure. For foliar uptake, the highest level of [(<span class="hlt">14</span>)<span class="hlt">C</span>] was found in the stem and root apex (both ≈2 × 10(4) dpm/g dry wt) (except for treated leaves), while the lowest level was found in the root base (<0.6 × 10(4) dpm/g dry wt).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012GeCoA..77..415B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012GeCoA..77..415B"><span id="translatedtitle"><span class="hlt">26</span><span class="hlt">Al</span>- 26Mg deficit dating ultramafic meteorites and silicate planetesimal differentiation in the early Solar System?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baker, Joel A.; Schiller, Martin; Bizzarro, Martin</p> <p>2012-01-01</p> <p>Meteorites with significantly sub-chondritic Al/Mg that formed in the first 2 million years of the Solar System should be characterised by deficits in the abundance of 26Mg (δ26Mg∗) due to the absence of in-growth of 26Mg from the decay of short-lived <span class="hlt">26</span><span class="hlt">Al</span> (t1/2 = 0.73 Myr). However, these 26Mg deficits will be small (δ26Mg∗ >-0.037‰) even for material that formed at the same time as the Solar System’s oldest solids - calcium-aluminium-rich inclusions - and thus measurement of these deficits is analytically challenging. Here, we report on a search for 26Mg deficits in three types of ultramafic meteorites (pallasites, ureilites and aubrites) by multiple-collector inductively coupled plasma mass spectrometry. A range of analytical tests were carried out including analysis of: (1) a range of synthetic Mg solution standards; (2) Mg gravimetrically doped with a high purity 26Mg spike; (3) Mg cuts collected sequentially from cation exchange separation columns with fractionated stable Mg isotope compositions; (4) Mg separated from samples that was bracketed by analyses of both DSM-3 and Mg separated from a natural olivine sample subjected to the same chemical processing as the samples. These tests confirm it is possible to resolve differences in δ26Mg∗ from the terrestrial materials that are ⩽0.005‰. However, if Mg yields from chemical separation are low or an inappropriate equilibrium-isotopically fractionated standard is used this will generate analytical artefacts on δ26Mg∗ when this is calculated with the kinetic/exponential mass fractionation law as is the case when correcting for instrumental mass bias during mass spectrometric analysis. Olivine from four different main group pallasites and four bulk ureilites have small deficits in the abundance of 26Mg with δ26MgDSM-3∗=-0.0120±0.0018‰ and δ26MgDSM-3∗=-0.0062±0.0023‰, respectively, relative to terrestrial olivine (δ26MgDSM-3∗=+0.0029±0.0028‰). Six aubrites have δ26MgDSM-3</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.9718N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.9718N"><span id="translatedtitle"><span class="hlt">26</span><span class="hlt">Al</span> - 10Be cosmogenic nuclide isochron burial dating in combination with luminescence dating of two Danube terraces</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Neuhuber, Stephanie; Braumann, Sandra; Lüthgens, Christopher; Fiebig, Markus; Häuselmann, Philipp; Schäfer, Jörg</p> <p>2016-04-01</p> <p>The Quaternary sediment record in the Vienna Basin is influenced by two main factors: (1) the tectonic development of a pull apart basin along a sinistral strike slip fault system between the Eastern Alps and the West Carpathians and by (2) strongly varying sediment supply during the Plio- and Pleistocene. From the Late Pannonian (8.8 Ma) onward a large-scale regional uplift (Decker et al., 2005) controls terrace formation in the Vienna Basin. The main sediment supply into the Vienna Basin originates from the Danube, and subordinately from tributaries to the south such as Piesting, Fischa, Leitha and from the north by the river March. Today the Danube forms a large floodplain that is bordered to the north by one large Pleistocene terrace, the Gänserndorf Terrace that is situated 17 m above todays water level. Farther to the east a smaller terrace, the Schlosshof Terrace, reaches 25 m above todays water level. These terrace levels are tilted by movement of underlying blocks (Peresson, 2006). Both, the Schlosshof and Gänserndorf terraces consist of successions of up to 2 m thick gravel beds with intercalated sand layers or -lenses that may locally reach thicknesses up to 0.8 m. At each terrace one gavel pit was selected to calculate the time of terrace deposition by luminescence dating in combination with <span class="hlt">26</span><span class="hlt">Al</span>/10Be cosmogenic nuclide isochrone dating (Balco and Rovery, 2008). Five quartz stones from the base of each terrace were physically and chemically processed to obtain Al and Be oxides for Acceleration Mass Spectrometry. Sand samples for luminescence dating were taken above the cosmogenic nuclide samples from the closest suitable sand body. Decker et al., 2005. QSR 24, 307-322 Peresson, 2006 Geologie der österreichischen Bundesländer Niederösterreich 255-258 Balco and Rovey, 2008. AJS 908, 1083-1114 Thanks to FWF P 23138-N19, OMAA 90öu17</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6577414','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6577414"><span id="translatedtitle">Distribution of photosynthetically fixed /sup <span class="hlt">14</span>/<span class="hlt">C</span> in perennial plant species of the northern Mojave Desert</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wallace, A.; Cha, J.W.; Romney, E.M.</p> <p>1980-01-01</p> <p>The distribution of photosynthate among plant parts subsequent to its production is needed to fully understand behavior of vegetation in any ecosystem. The present study, undertaken primarily to obtain information on transport of assimilates into roots of desert vegetation, was conducted in the northern Mojave Desert, where the mean annual rainfall is about 10 cm. Shoots of Ambrosia dumosa (A. Gray) Payne plants were exposed to /sup 14/CO/sub 2/ in 1971, and the distribution of /sup <span class="hlt">14</span>/<span class="hlt">C</span> in roots, stems, and leaves was subsequently measured at 1 week, 2 months, and 5 months. Only about 12 percent of the /sup <span class="hlt">14</span>/<span class="hlt">C</span> photosynthate was stored in the root. Much of that stored in stems was available for new leaf growth. Photosynthate was labeled with /sup <span class="hlt">14</span>/<span class="hlt">C</span> for 24 plants representing eight species in 1972. Results showed that after 127 days the mean percentage of /sup <span class="hlt">14</span>/<span class="hlt">C</span> in roots as compared with the estimate of that originally fixed was 11.8; the percentage in stems was 43.8. To check the validity of the /sup <span class="hlt">14</span>/<span class="hlt">C</span> data, root growth of eight perennial desert plants grown in the glasshouse was followed as plants increased in size. The mean percent of the whole plant that was root for eight species was 17.7 percent. The mean proportion of the increase in plant weights that went below ground for the eight species was 19.5 percent. This value is higher than the fraction of /sup <span class="hlt">14</span>/<span class="hlt">C</span> found below ground, and therefore the /sup <span class="hlt">14</span>/<span class="hlt">C</span> technique underestimates the movement of C to roots. Results of an experiment designed to test the value of the /sup <span class="hlt">14</span>/<span class="hlt">C</span>-pulse technique for determining current root growth for some perennial species from the desert indicated that the transition part of roots where root growth continued after exposure to /sup <span class="hlt">14</span>/<span class="hlt">C</span> was highly labeled. Old growth contained less /sup <span class="hlt">14</span>/<span class="hlt">C</span> than new growth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007NIMPB.259..767D&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007NIMPB.259..767D&link_type=ABSTRACT"><span id="translatedtitle">Disposition of <span class="hlt">14</span><span class="hlt">C</span>-β-carotene following delivery with autologous triacylglyceride-rich lipoproteins</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dueker, Stephen R.; Vuong, Le Thuy; Faulkner, Brian; Buchholz, Bruce A.; Vogel, John S.</p> <p>2007-06-01</p> <p>Following ingestion, a fraction of β-carotene is cleaved into vitamin A in the intestine, while another is absorbed intact and distributed among tissues and organs. The extent to which this absorbed β-carotene serves as a source of vitamin A is unknown in vivo. In the present study we use the attomole sensitivity of accelerator mass spectrometry (AMS) for <span class="hlt">14</span><span class="hlt">C</span> to quantify the disposition of <span class="hlt">14</span><span class="hlt">C</span>-β-carotene (930 ng; 60.4 nCi of activity) after intravenous injection with an autologous triacylglyceride-rich lipoprotein fraction in a single volunteer. Total <span class="hlt">14</span><span class="hlt">C</span> was quantified in serial plasma samples and also in triglyceride-rich, and low density lipoprotein, subfractions. The appearance of <span class="hlt">14</span><span class="hlt">C</span>-retinol, the circulating form of vitamin A in plasma, was determined by chromatographic separation of plasma retinol extracts prior to AMS analysis. The data showed that <span class="hlt">14</span><span class="hlt">C</span> concentrations rapidly decayed within the triglyceride-rich lipoprotein fractions after injection, whereas low density lipoprotein <span class="hlt">14</span><span class="hlt">C</span> began a significant rise in <span class="hlt">14</span><span class="hlt">C</span> 5 h post dose. Plasma <span class="hlt">14</span><span class="hlt">C</span>-retinol also appeared at 5 h post dose and its concentrations were maintained above baseline for >88 days. Based upon comparisons of <span class="hlt">14</span><span class="hlt">C</span>-retinol concentrations following an earlier study with orally dosed <span class="hlt">14</span><span class="hlt">C</span>-β-carotene, a molar vitamin A value of the absorbed β-carotene of 0.19 was derived, meaning that 1 mole of absorbed β-carotene provides 0.19 moles of vitamin A. This is the first study to show that infused β-carotene contributes to the vitamin A economy in humans in vivo.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21422708','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21422708"><span id="translatedtitle">Utilization of orally administered D-[<span class="hlt">14</span><span class="hlt">C</span>]mannitol via fermentation by intestinal microbes in rats.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hongo, Ryoko; Nakamura, Sadako; Oku, Tsuneyuki</p> <p>2010-01-01</p> <p>To investigate the available energy of orally administered [(<span class="hlt">14</span>)<span class="hlt">C</span>]mannitol via intestinal microbes, [(<span class="hlt">14</span>)<span class="hlt">C</span>]mannitol (222 kBq, 105 mg) or [(<span class="hlt">14</span>)<span class="hlt">C</span>]glucose (222 kBq, 105 mg) was administered to conventional rats and antibiotics-treated rats whose intestinal microbes were depleted by drinking water containing antibiotics, respectively. The exhausted CO(2), feces and urine were then separately collected at 2, 4, 6, 8, 10, 12 and 24 h after administration of the test solution. In the conventional rats, 45% of administered radioactivity was recovered as (14)CO(2) in the administration of [(<span class="hlt">14</span>)<span class="hlt">C</span>]mannitol, while 57% of administered radioactivity was recovered as (14)CO(2) following the administration of [(<span class="hlt">14</span>)<span class="hlt">C</span>]glucose for 24 h. The time sequence for the (14)CO(2) excretion from [(<span class="hlt">14</span>)<span class="hlt">C</span>]mannitol was delayed as compared to [(<span class="hlt">14</span>)<span class="hlt">C</span>]glucose by about 4-6 h (p<0.05). However, when [(<span class="hlt">14</span>)<span class="hlt">C</span>]mannitol was orally administered to antibiotics-treated rats, only 3% of administered radioactivity was excreted as (14)CO(2) for 24 h. The total radioactivity of the gastrointestinal contents and feces for 24 h after administration was over 70%, much higher than those of the conventional rats (p<0.05). When a half dose (222 kBq, 52.5 mg) of [(<span class="hlt">14</span>)<span class="hlt">C</span>]mannitol was administered to conventional rats, the recovery as (14)CO(2) for 24 h (%) was significantly higher than that of a regular dose of [(<span class="hlt">14</span>)<span class="hlt">C</span>]mannitol (105 mg). When cold mannitol (105 mg) was orally administered to the antibiotics-treated rats, about 9% of intact mannitol was excreted in feces within 48 h after administration. However, no intact mannitol was detected in the conventional rats. These results demonstrate that more than 95% of mannitol administered orally is utilized via fermentation by intestinal microbes.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6467433','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6467433"><span id="translatedtitle">Appearance of circulating and tissue /sup <span class="hlt">14</span>/<span class="hlt">C</span>-lipids after oral /sup <span class="hlt">14</span>/<span class="hlt">C</span>-tripalmitate administration in the late pregnant rat</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Argiles, J.; Herrera, E.</p> <p>1989-02-01</p> <p>Studies were performed to determine whether and/or how dietary lipids participate in maternal hypertriglyceridemia during late gestation in the rat. After oral administration of glycerol-tri(1-<span class="hlt">14</span><span class="hlt">C</span>)-palmitate, total radioactivity in plasma increased more rapidly in 20-day pregnant rats than in either 19-day pregnant rats or virgin controls. At the peak of plasma radioactivity, four hours after the tracer was administered, most of the plasma label corresponded to <span class="hlt">14</span><span class="hlt">C</span>-lipids in triglyceride-rich lipoproteins (d less than 1.006), and when expressed per micromol of triglyceride, values were higher in pregnant than in virgin rats. The difference was less after 24 hours, although at this time the level of <span class="hlt">14</span><span class="hlt">C</span>-lipids in d less than 1.006 lipoproteins was still higher in 20-day pregnant rats than in virgins. Tissue <span class="hlt">14</span><span class="hlt">C</span>-lipids, as expressed per gram of fresh weight, were similar in pregnant and virgin rats, but the values in mammary glands were much higher in the former group. Estimated recovery of administered radioactivity four hours after tracer in total white adipose tissue, mammary glands, and plasma lipids was higher in pregnant than in virgin rats. No difference was found between 20-day pregnant and virgin rats either in the label retained in the gastrointestinal tract or in that exhaled as <span class="hlt">14</span><span class="hlt">C</span>-CO2 during the first four hours following oral administration of <span class="hlt">14</span><span class="hlt">C</span>-tripalmitate. These findings plus the known maternal hyperphagia, indicate that in the rat at late pregnancy triglyceride intestinal absorption is unchanged or even enhanced and that dietary lipids actively contribute to both maternal hypertriglyceridemia and lipid uptake by the mammary gland.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5337880','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5337880"><span id="translatedtitle">The effect of 6-aminonicotinamide on the levels of brain amino acids and glucose, and their labeling with <span class="hlt">14</span><span class="hlt">C</span> after injection of (U-<span class="hlt">14</span><span class="hlt">C</span>) glucose</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gaitonde, M.K.; Lewis, L.P.; Evans, G.; Clapp, A.</p> <p>1981-10-01</p> <p>The brains of rats paralysed at 4 hr after the administration of 6-aminonicotinamide were found to contain decreased levels of glutamate and gamma-aminobutyrate. The glucose content of the brain of the treated rats was several fold higher than in controls. The incorporation of <span class="hlt">14</span><span class="hlt">C</span> into brain amino acids at 30 min after the injection of (U-<span class="hlt">14</span><span class="hlt">C</span>)glucose was decreased by 16%: this was attributed to mainly decreased labeling of glutamate and associated amino acids. The results are discussed in the light of previous findings that the administration of 6-aminonicotinamide resulted in the blockade of the direct oxidation of glucose by the pentose phosphate pathway.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3633810','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3633810"><span id="translatedtitle">Lack of tissue renewal in human adult Achilles tendon is revealed by nuclear bomb <span class="hlt">14</span><span class="hlt">C</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Heinemeier, Katja Maria; Schjerling, Peter; Heinemeier, Jan; Magnusson, Stig Peter; Kjaer, Michael</p> <p>2013-01-01</p> <p>Tendons are often injured and heal poorly. Whether this is caused by a slow tissue turnover is unknown, since existing data provide diverging estimates of tendon protein half-life that range from 2 mo to 200 yr. With the purpose of determining life-long turnover of human tendon tissue, we used the <span class="hlt">14</span><span class="hlt">C</span> bomb-pulse method. This method takes advantage of the dramatic increase in atmospheric levels of <span class="hlt">14</span><span class="hlt">C</span>, produced by nuclear bomb tests in 1955–1963, which is reflected in all living organisms. Levels of <span class="hlt">14</span><span class="hlt">C</span> were measured in 28 forensic samples of Achilles tendon core and 4 skeletal muscle samples (donor birth years 1945–1983) with accelerator mass spectrometry (AMS) and compared to known atmospheric levels to estimate tissue turnover. We found that Achilles tendon tissue retained levels of <span class="hlt">14</span><span class="hlt">C</span> corresponding to atmospheric levels several decades before tissue sampling, demonstrating a very limited tissue turnover. The tendon concentrations of <span class="hlt">14</span><span class="hlt">C</span> approximately reflected the atmospheric levels present during the first 17 yr of life, indicating that the tendon core is formed during height growth and is essentially not renewed thereafter. In contrast, <span class="hlt">14</span><span class="hlt">C</span> levels in muscle indicated continuous turnover. Our observation provides a fundamental premise for understanding tendon function and pathology, and likely explains the poor regenerative capacity of tendon tissue.—Heinemeier, K. M., Schjerling, P., Heinemeier, J., Magnusson, S. P., Kjaer, M. Lack of tissue renewal in human adult Achilles tendon is revealed by nuclear bomb <span class="hlt">14</span><span class="hlt">C</span>. PMID:23401563</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NIMPB.361..609P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NIMPB.361..609P"><span id="translatedtitle">The distribution of Δ<span class="hlt">14</span><span class="hlt">C</span> in Korea from 2010 to 2013</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Park, J. H.; Hong, W.; Xu, X.; Park, G.; Sung, K. S.; Sung, Kilho; Lee, Jong-geol; Nakanishi, T.; Park, Hyo-Seok</p> <p>2015-10-01</p> <p>Δ<span class="hlt">14</span><span class="hlt">C</span> values of leaves of a deciduous tree record to those of atmospheric CO2 within error and were used to map out Δ<span class="hlt">14</span><span class="hlt">C</span> distribution in Korea. We collected ginkgo (Ginkgo biloba Linnaeus, a deciduous tree) leaf samples in mid-June to early July from 2009 to 2013 in Korea to obtain the regional distribution of Δ<span class="hlt">14</span><span class="hlt">C</span>. Commonly CO2 emitted from fossil fuel consumption dilutes atmospheric <span class="hlt">14</span><span class="hlt">C</span>, while operations and accidents at nuclear power plants can increase it. The distribution maps of Δ<span class="hlt">14</span><span class="hlt">C</span> from 2010 to 2013 in Korea shows that Δ<span class="hlt">14</span><span class="hlt">C</span> values in the northwestern and southeastern parts of Korea are lower than those of the other parts of Korea, which is consistent with the population and industry patterns. Decrease rates of annually averaged Δ<span class="hlt">14</span><span class="hlt">C</span> values in Korea over the study period are larger than those of Pt. Barrow, Alaska, USA (71.3°N, 156.5°W), so the difference between them and those of Pt. Barrow, Alaska, USA became larger annually. This may be due to the increase in fossil fuel consumption in Korea and China. The decrease rate between 2010 and 2011 was smaller than in other years. This could be the effect of the Fukushima power plant accident which occurred in March 11, 2011, but further study is needed to clarify it.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/15011616','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/15011616"><span id="translatedtitle">Discussion: Reporting and calibration of post-bomb <span class="hlt">14</span><span class="hlt">C</span> data</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Reimer, P J; Brown, T A; Reimer, R W</p> <p>2004-10-11</p> <p>The definitive paper by Stuiver and Polach (1977) established the conventions for reporting of {sup <span class="hlt">14</span>}<span class="hlt">C</span> data for chronological and geophysical studies based on the radioactive decay of {sup <span class="hlt">14</span>}<span class="hlt">C</span> in the sample since the year of sample death or formation. Several ways of reporting {sup <span class="hlt">14</span>}<span class="hlt">C</span> activity levels relative to a standard were also established, but no specific instructions were given for reporting nuclear weapons testing (post-bomb) {sup <span class="hlt">14</span>}<span class="hlt">C</span> levels in samples. Because the use of post-bomb {sup <span class="hlt">14</span>}<span class="hlt">C</span> is becoming more prevalent in forensics, biology, and geosciences, a convention needs to be adopted. We advocate the use of fraction modern with a new symbol F{sup <span class="hlt">14</span>}<span class="hlt">C</span> to prevent confusion with the previously used Fm, which may or may not have been fractionation corrected. We also discuss the calibration of post-bomb {sup <span class="hlt">14</span>}<span class="hlt">C</span> samples and the available datasets and compilations, but do not give a recommendation for a particular dataset.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7086612','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7086612"><span id="translatedtitle">Secretin enhances (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)erythritol clearance in unanesthetized dogs</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lewis, M.H.; Baker, A.L.; Dhorajiwala, J.; Moossa, A.R.</p> <p>1982-01-01</p> <p>To determine the effect of secretin infusion on clearance of inert markers into bile, unanesthetized dogs fitted with Thomas cannulas received continuous infusions of (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)erythritol and (/sup 3/H)inulin throughout study. Taurocholic acid administered sequentially at 9.0, 20.0, and 40.0 mumol/min enhanced (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)erythritol clearance, and GIH secretin (3 units/min) administered along with TCA (40.0 mumol/min) increased (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)erythritol clearance from 4.9 +/- 1.2 ml/10 min to 6.8 +/- 1.3 ml/10 min (P less than 0.001), but simultaneously measured (/sup 3/H)inulin clearance was unaltered. Secretin alone also increased (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)erythritol clearance but did not alter (/sup 3/H)inulin clearance. The increase in (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)erythritol clearance per unit increase in bile flow was less during secretin infusion than TCA. Thus, secretin increases (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)erythritol transport through restricted channels, probably distal to the canaliculi. (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)Erythritol may not be an accurate marker for canalicular bile flow in dogs during secretin infusion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5186780','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5186780"><span id="translatedtitle">The biological fate of sup <span class="hlt">14</span> <span class="hlt">C</span>-dimercaptosuccinic acid in monkeys and rabbits</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tillotson, J.A.; Boswell, G.; Kincannon, L.; Speckman, C.L.</p> <p>1989-09-01</p> <p>The biological fate of {sup <span class="hlt">14</span>}<span class="hlt">C</span>-labeled dimercaptosuccinic acid (DMSA) in monkeys and rabbits was determined by measuring the {sup <span class="hlt">14</span>}<span class="hlt">C</span> activity in their urine, feces, and expired air ({sup 14}CO{sub 2}). Monkeys absorbed less than 20% DMSA from three oral dose levels (0.082, 0.16, and 0.5 mmol/kg) of {sup <span class="hlt">14</span>}<span class="hlt">C</span>-DMSA, and the rabbits absorbed 32% DMSA or less from an oral dose of {sup <span class="hlt">14</span>}<span class="hlt">C</span>-DMSA (0.5 mmol/kg). Although the bioavailability of DMSA was limited in either species, DMSA was detected in the blood of both species within minutes after oral dosing. In either species, most of the radiolabel from the absorbed {sup <span class="hlt">14</span>}<span class="hlt">C</span>-DMSA was detected in the urine within 12 hours. We also developed a sensitive assay for directly measuring levels of DMSA (as free thiols) in blood. Intact DMSA was not detected in the blood of the monkeys or the rabbits more than 200 minutes after oral or intravenous dosing at 0.5 mmol DMSA/kg body weight. However, {sup <span class="hlt">14</span>}<span class="hlt">C</span> activity in blood and urine of the monkeys was measurable 72 hours after this dose. Differences between measured {sup <span class="hlt">14</span>}<span class="hlt">C</span> concentrations and intact DMSA concentrations in the blood suggest the presence of DMSA metabolites that have longer half-lives than DMSA. Consequently, until the biological activities of these compounds are identified, the pharmacokinetic analysis of DMSA may be incomplete.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001AIPC..576..394M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AIPC..576..394M"><span id="translatedtitle">Biokinetic and dosimetric investigations of <span class="hlt">14</span><span class="hlt">C</span>-labeled substances in man using AMS</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mattsson, Sören; Gunnarsson, Mikael; Svegborn, Sigrid Leide; Nosslin, Bertil; Nilsson, Lars-Erik; Thorsson, Ola; Valind, Sven; Åberg, Magnus; Östberg, Henrik; Hellborg, Ragnar; Stenström, Kristina; Erlandsson, Bengt; Faarinen, Mikko; Kiisk, Madis; Magnusson, Carl-Erik; Persson, Per; Skog, Göran</p> <p>2001-07-01</p> <p>Up to now, radiation dose estimates from radiopharmaceuticals, labeled with pure β-emitting radionuclides, e.g., <span class="hlt">14</span><span class="hlt">C</span> or 3H have been very uncertain. Using accelerator mass spectrometry (AMS) we have derived new and improved data for <span class="hlt">14</span><span class="hlt">C</span>-triolein and <span class="hlt">14</span><span class="hlt">C</span>-urea and are currently running a program related to the biokinetics and dosimetry of <span class="hlt">14</span><span class="hlt">C</span>-glycocholic acid and <span class="hlt">14</span><span class="hlt">C</span>-xylose. The results of our investigations have made it possible to widen the indications for the clinical use of the <span class="hlt">14</span><span class="hlt">C</span>-urea test for Helicobacter pylori infection in children. The use of ultra-low activities, which is possible with AMS (down to 1/1000 of that used for liquid scintillation counting), has opened the possibility for metabolic investigations on children as well as on other sensitive patient groups like new-borns, and pregnant or breast-feeding women. Using the full potential of AMS, new <span class="hlt">14</span><span class="hlt">C</span>-labeled drugs could be tested on humans at a much earlier stage than today, avoiding uncertain extrapolations from animal models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=541803','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=541803"><span id="translatedtitle"><span class="hlt">14</span><span class="hlt">C</span>2H4: Its Incorporation and Metabolism by Pea Seedlings under Aseptic Conditions 1</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Beyer, Elmo M.</p> <p>1975-01-01</p> <p>The effects of various treatments on the recently reported system in pea (Pisum sativum cv. Alaska), which results in (a) the incorporation of <span class="hlt">14</span><span class="hlt">C</span>2H4 into the tissue and (b) the conversion of <span class="hlt">14</span><span class="hlt">C</span>2H4 to 14CO2, was investigated using 2-day-old etiolated seedlings which exhibit a maximum response. Heat treatment (80 C, 1 min) completely inhibited both a and b, whereas homogenization completely inhibited b but only partially inhibited a. Detaching the cotyledons from the root-shoot axis immediately before exposing the detached cotyledons together with the root-shoot axis to <span class="hlt">14</span><span class="hlt">C</span>2H4 markedly reduced both a and b. Increasing the <span class="hlt">14</span><span class="hlt">C</span>2H4 concentration from 0.14 to over 100 μl/l progressively increased the rate of a and b with tissue incorporation being greater than <span class="hlt">14</span><span class="hlt">C</span>2H4 to 14CO2 conversion only below 0.3 μl/l <span class="hlt">14</span><span class="hlt">C</span>2H4. Reduction of the O2 concentration reduced both a and b, with over 99% inhibition occurring under anaerobic conditions. The addition of CO2 (5%) severely inhibited <span class="hlt">14</span><span class="hlt">C</span>2H4 to 14CO2 conversion without significantly affecting tissue incorporation. Exposure of etiolated seedlings to fluorescent light during <span class="hlt">14</span><span class="hlt">C</span>2H4 treatment was without effect. Similarly, indoleacetic acid, gibberellic acid, benzyladenine, abscisic acid, and dibutyryl cyclic adenosine monophosphate had no significant effect on either a or b. The possibilities that the incorporation of <span class="hlt">14</span><span class="hlt">C</span>2H4 into pea tissues and its conversion to 14CO2 is linked to ethylene action, or that it represents a means of reducing the endogenous ethylene level, are discussed. Several problems encountered with the use of polyethylene vials, rubber serum stoppers, Clorox, and microbial contamination are also described. Images PMID:16659286</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6602935','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6602935"><span id="translatedtitle">Possible cluster preformation in the sup <span class="hlt">14</span> <span class="hlt">C</span> decay of sup 223 Ra</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hussonnois, M.; Le Du, J.F.; Brillard, L.; Ardisson, G. )</p> <p>1990-08-01</p> <p>A recent experiment on the {sup <span class="hlt">14</span>}<span class="hlt">C</span> fine structure has shown that the branching ratio to {sup 209}Pb ground state is quite different from the one predicted by the various models of cluster emission. Assuming that the {sup <span class="hlt">14</span>}<span class="hlt">C</span> is preformed in the {sup 223}Ra nucleus, we have calculated the hindrance factor {ital F}{sup <span class="hlt">14</span>}<span class="hlt">C</span> of the three {sup <span class="hlt">14</span>}<span class="hlt">C</span> branches to {sup 209}Pb states with a barrier penetrability approximated by a square-well Coulomb potential. The {ital F}{sup <span class="hlt">14</span>}<span class="hlt">C</span>=3.9 and 4.6 values found for the {sup <span class="hlt">14</span>}<span class="hlt">C</span> transitions to the two excited states at 779 keV ({ital I}{sup {pi}}=11/2{sup +}) and 1423 keV ({ital I}{sup {pi}}=15/2{sup {minus}}), respectively, reveal that the cluster formation amplitudes in both transitions are close to those of the {sup 222}Ra and {sup 224}Ra {sup <span class="hlt">14</span>}<span class="hlt">C</span> decays. Such values could be the result of {vert bar}{ital nlj}{r angle} shell-model components common to both the wave functions of the octupole deformed {sup 223}Ra nucleus and of the two first excited states of {sup 209}Pb spherical nucleus. The high hindrance factor {ital F}{sup <span class="hlt">14</span>}<span class="hlt">C</span>=583 of the {sup <span class="hlt">14</span>}<span class="hlt">C</span> branch to the {sup 209}Pb ground state ({ital I}{sup {pi}}=9/2{sup +}) could reveal the absence of {vert bar}1{ital g}{sub 9/2}{r angle} shell-model component in the {sup 223}Ra wave function.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/15011396','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/15011396"><span id="translatedtitle">Timing is Everything:The Boon and Bane of <span class="hlt">14</span><span class="hlt">C</span> Geochronology</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Guilderson, T; Guilderson, T; Reimer, P J; Brown, T</p> <p>2004-10-29</p> <p>There are underappreciated limitations of the conversion of {sup <span class="hlt">14</span>}<span class="hlt">C</span>-ages to the fixed, calendrical time-scale that bear directly upon our understanding of the dynamic climate system, or the relationship between the collapse of one civilization and it's neighbor's. In this paper we present a quantitative assessment of the limits of {sup <span class="hlt">14</span>}<span class="hlt">C</span>-geochronology and calibration onto the absolute calendrical time-scale over the Holocene. We take into account not only the inherent limitations of the {sup <span class="hlt">14</span>}<span class="hlt">C</span>-calendar calibration curve, but also analytical uncertainties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1264759','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1264759"><span id="translatedtitle">The incorporation of isotopic carbon (<span class="hlt">14</span><span class="hlt">C</span>) into the cerebral glycogen of rabbits</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Coxon, R. V.; Gordon-Smith, E. C.; Henderson, J. R.</p> <p>1965-01-01</p> <p>1. The incorporation of <span class="hlt">14</span><span class="hlt">C</span> into the brain glycogen of conscious rabbits with labelled glucose, bicarbonate and glutamate as precursors has been studied. 2. Substantial incorporation from all these precursors was demonstrated after an interval of 5hr. from their injection. 3. With [<span class="hlt">14</span><span class="hlt">C</span>]glucose maximal incorporation occurred at about 8hr. from the time of injection. 4. Hydrocortisone led to increased incorporation of <span class="hlt">14</span><span class="hlt">C</span> from labelled glucose. 5. Some comparisons between the turnover of brain glycogen and that of skeletal and cardiac muscle are reported. PMID:5881665</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5220754','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5220754"><span id="translatedtitle">Synthesis, storage, and stability of (4-/sup <span class="hlt">14</span>/<span class="hlt">C</span>)oxaloacetic acid</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hatch, M.D.; Heldt, H.W.</p> <p>1985-03-01</p> <p>A simple procedure for preparing (4-/sup <span class="hlt">14</span>/<span class="hlt">C</span>)oxaloacetic acid based on the reaction between (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)HCO-3 and phosphoenolpyruvate catalyzed by phosphoenolpyruvate carboxylase is described. A simple method for preparing highly purified phosphoenolpyruvate carboxylase from maize leaves is described and the degradation of oxaloacetate under conditions of varying pH and divalent metal ion concentration is reported. (4-/sup <span class="hlt">14</span>/<span class="hlt">C</span>)Oxaloacetic acid is stable for several months in 0.1 M HCl solution at -80 degrees C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.P34C..03N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.P34C..03N"><span id="translatedtitle">Formation age and geomorphologic history of the Lonar impact crater deduced from in- situ cosmogenic 10Be and <span class="hlt">26</span><span class="hlt">Al</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nakamura, A.; Yokoyama, Y.; Sekine, Y.; Goto, K.; Komatsu, G.; Kumar, P.; Matsuzaki, H.; Matsui, T.</p> <p>2013-12-01</p> <p>Impact cratering is a dominant surface modification process on planetary surfaces. In the inner solar system, the large majority of impacts occur on bodies covered by primitive igneous rocks. However, most of the impacts remaining on Earth surface are on different rock types than that of the inner planet and hence geologic knowledge derived from Earth's surface cannot be translated readily. The Lonar crater is a 1.88-km-diameter crater located on the Deccan basaltic traps in India (ca. 65 Ma), and is one of a few craters on Earth bombarded directly on basaltic lava flows. Thus, the Lonar crater provides a rare opportunity to study impact structures on the basaltic surfaces of other terrestrial planets and the Moon. Since the ages of terrestrial impact structures is a key to understand geomorphological processes after the impact, various dating methods have been applied to the Lonar Crater such as fission track (Storzer and Koeberl, 2004), radiocarbon (Maloof, 2010), thermoluminescence (Sengupta et al., 1997), and 40Ar/39Ar (Jourdan et al., 2011). Yet, a large discrepancy between these methods ranging from ca. 1.79 to 570 ka has been resulted. Here we report surface exposure ages based on in-situ cosmogenic 10Be and <span class="hlt">26</span><span class="hlt">Al</span> in order to obtain a precise age of the Lonar crater formation as well as to study the geomorphologic evolution. The samples are collected from the topographic highs on the rim of the crater and from the ejecta blanket. Exposure ages together with newly obtained radiocarbon age of pre-impact soil indicate much younger ages than that of obtained from 40Ar/39Ar method. This suggests the potential bias because of inherited 40Ar in impact glass. Systematically young exposure age from the rim samples compared to the samples from the ejecta blanket indicate that the rim of the Lonar crater is being actively eroded. Spatial distributions of geomorphic ages observed from the Lonar creator is not the same as the pattern reported from the well</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6867649','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6867649"><span id="translatedtitle">Systemic distribution of sup <span class="hlt">14</span> <span class="hlt">C</span>-labeled formaldehyde applied in the root canal following pulpectomy</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hata, G.I.; Nishikawa, I.; Kawazoe, S.; Toda, T.</p> <p>1989-11-01</p> <p>The systemic distribution of {sup <span class="hlt">14</span>}<span class="hlt">C</span>-labeled formaldehyde which had been placed in the root canals of the canines of cats following pulpectomies was studied using liquid scintillation counting and whole-body autoradiographic technique. Radioactive {sup <span class="hlt">14</span>}<span class="hlt">C</span> which had been placed in the canals was found in the plasma 30 min after the root canal procedure. The recovery of systemic {sup <span class="hlt">14</span>}<span class="hlt">C</span> radioactivity increased with time. In addition, it seemed that approximately 3% of the dose placed in the teeth was excreted in the urine within 36 h. Whole-body autoradiograms indicated extensive concentration of {sup <span class="hlt">14</span>}<span class="hlt">C</span> radioactivity in tissues other than those analyzed with the liquid scintillation technique.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18533685','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18533685"><span id="translatedtitle">Intracavity optogalvanic spectroscopy. An analytical technique for <span class="hlt">14</span><span class="hlt">C</span> analysis with subattomole sensitivity.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Murnick, Daniel E; Dogru, Ozgur; Ilkmen, Erhan</p> <p>2008-07-01</p> <p>We show a new ultrasensitive laser-based analytical technique, intracavity optogalvanic spectroscopy, allowing extremely high sensitivity for detection of (<span class="hlt">14</span>)<span class="hlt">C</span>-labeled carbon dioxide. Capable of replacing large accelerator mass spectrometers, the technique quantifies attomoles of (<span class="hlt">14</span>)<span class="hlt">C</span> in submicrogram samples. Based on the specificity of narrow laser resonances coupled with the sensitivity provided by standing waves in an optical cavity and detection via impedance variations, limits of detection near 10(-15) (<span class="hlt">14</span>)<span class="hlt">C</span>/(12)C ratios are obtained. Using a 15-W (14)CO2 laser, a linear calibration with samples from 10(-15) to >1.5 x 10(-12) in (<span class="hlt">14</span>)<span class="hlt">C</span>/(12)C ratios, as determined by accelerator mass spectrometry, is demonstrated. Possible applications include microdosing studies in drug development, individualized subtherapeutic tests of drug metabolism, carbon dating and real time monitoring of atmospheric radiocarbon. The method can also be applied to detection of other trace entities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/6660522','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/6660522"><span id="translatedtitle">A radiochemical assay for argininosuccinate synthetase with [U-<span class="hlt">14</span><span class="hlt">C</span>]aspartate.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ratner, S</p> <p>1983-12-01</p> <p>A simple and sensitive radiochemical procedure to assay argininosuccinate synthetase activity in crude tissue homogenates and lysates of cultured cells is described. The new method depends on the location of <span class="hlt">14</span><span class="hlt">C</span>, uniformly, in the four carbons of aspartate. On incubation in the presence of excess of L-[U-<span class="hlt">14</span><span class="hlt">C</span>]aspartate, L-citrulline, ATP, and an ATP-generating system, argininosuccinase and arginase, the [<span class="hlt">14</span><span class="hlt">C</span>]fumarate formed is measured as the sum of malate and fumarate. After acidification the latter two acids are separated from [<span class="hlt">14</span><span class="hlt">C</span>]aspartate on a small Dowex-50 column by elution with a few milliliters of water; the unutilized amino acid substrates remain on the column. With a specific radioactivity of 9 X 10(4) cpm, 1 to 2 nmol of product can be accurately measured under kinetically optimum conditions. PMID:6660522</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6619959','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6619959"><span id="translatedtitle">Exotic nuclear decay of /sup 223/Ra by emission of /sup <span class="hlt">14</span>/<span class="hlt">C</span> nuclei</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gales, S.; Hourani, E.; Hussonnois, M.; Schapira, J.P.; Stab, L.; Vergnes, M.</p> <p>1984-08-20</p> <p>The exotic nuclear decay of /sup 223/Ra by emission of /sup <span class="hlt">14</span>/<span class="hlt">C</span> nuclei has been investigated by use of an intense radioactive /sup 227/Ac source and a magnetic spectrometer with a large solid angle. After a run of 5 d, a group of eleven events was observed at the expected location of /sup <span class="hlt">14</span>/<span class="hlt">C</span> in a ..delta..E-E telescope calibrated with a /sup <span class="hlt">14</span>/<span class="hlt">C</span> beam. A branching ratio of (5.5 +- 2.0) x 10/sup -10/ was measured for the emission of /sup <span class="hlt">14</span>/<span class="hlt">C</span> nuclei relative to ..cap alpha.. particles from /sup 223/Ra in agreement with the previously reported ratio of (8.5 +- 2.5) x 10/sup -10/. .AE</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6199518','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6199518"><span id="translatedtitle">Interpretation of the fine structure in the sup <span class="hlt">14</span> <span class="hlt">C</span> radioactive decay of sup 223 Ra</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sheline, R.K. ); Ragnarsson, I. )</p> <p>1991-03-01</p> <p>The experimental hindrance factors determined from the fine structure in the {sup <span class="hlt">14</span>}<span class="hlt">C</span> decay of {sup 223}Ra are strikingly similar to the hindrance factors observed in the alpha decay of odd-{ital A} reflection-asymmetric deformed nuclei in spite of the deformed to spherical shape which occurs in the {sup <span class="hlt">14</span>}<span class="hlt">C</span> decay. Calculations of the overlap between the reflection-asymmetric ground state of {sup 223}Ra and the spherical shell-model orbitals of {sup 209}Pb involved in the {sup <span class="hlt">14</span>}<span class="hlt">C</span> decay are consistent with the experimental hindrance factors from the {sup <span class="hlt">14</span>}<span class="hlt">C</span> fine structure except that the {ital j}{sub 15/2} orbital is more strongly populated experimentally than the calculations suggest.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5397668','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5397668"><span id="translatedtitle">Enhancement of radioactivity of /sup <span class="hlt">14</span>/<span class="hlt">C</span>-/sup 12/C mixtures via partial reduction</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Stevenson, G.R.; Lauricella, T.L.</p> <p>1986-08-20</p> <p>The solution electron affinities of perdeuterated polyaromatics are less than those of the protiated materials. This observation prompted the investigation of the possibility of increasing the radioactivity of benzophenone-carbonyl-/sup <span class="hlt">14</span>/<span class="hlt">C</span> (BZO-<span class="hlt">14</span><span class="hlt">C</span>)-cold benzophenone (BZO-12C) mixtures via the partial reduction of these mixtures to the ketyls. The /sup <span class="hlt">14</span>/<span class="hlt">C</span>-depleted benzophenones left in the reaction vessel in the form of Na/sup +/(NH/sub 3/)BZO/sup -/ can be recovered by simply adding a solution of I/sub 2/ in tetrahydrofuran to the solid salt. Further, there is no theoretical limit as to how much the radioactivity of the sample can be enhanced by passing /sup <span class="hlt">14</span>/<span class="hlt">C</span>-enhanced material through this process consecutively, up to the point where the pure carbon-14 compound is obtained.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMPP21B1798S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMPP21B1798S"><span id="translatedtitle">No evidence for a deglacial intermediate water Δ<span class="hlt">14</span><span class="hlt">C</span> anomaly in the SW Atlantic</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sortor, R. N.; Lund, D. C.</p> <p>2011-12-01</p> <p>The last deglaciation was characterized by an increase in atmospheric pCO2 and decrease in atmospheric radiocarbon activity. One hypothesis is that these changes were due to out-gassing of <span class="hlt">14</span><span class="hlt">C</span>-depleted carbon from the abyssal ocean (Broecker and Barker, 2007). Reconstructions of foraminiferal Δ<span class="hlt">14</span><span class="hlt">C</span> from the eastern tropical Pacific (Marchitto et al., 2007; Stott et al. 2009), Arabian Sea (Bryan et al., 2010), and high latitude North Atlantic (Thornalley et al., 2011) show that severe depletions in <span class="hlt">14</span><span class="hlt">C</span> occurred at intermediate water depths during the last deglaciation. It has been suggested that <span class="hlt">14</span><span class="hlt">C</span>-depleted water from the abyss upwelled in the Southern Ocean and was then carried by Antarctic Intermediate Water (AAIW) to these sites (Marchitto et al., 2007). On the South Icelandic Rise, Thornalley et al. (2011) find deglacial Δ<span class="hlt">14</span><span class="hlt">C</span> values up to 600% lower than the atmosphere. Since North Atlantic deep waters are not believed to be old enough to cause such an anomaly (Robinson et al. 2005), one possible source is AAIW (Thornalley et al., 2011). Here we evaluate whether or not a large deglacial <span class="hlt">14</span><span class="hlt">C</span> anomaly occurred at intermediate depths in the Southwest Atlantic. We find that the deglacial Δ<span class="hlt">14</span><span class="hlt">C</span> trend at our site is similar to the atmospheric Δ<span class="hlt">14</span><span class="hlt">C</span> trend. Our results are also largely consistent with data from U/Th-dated corals at shallower water depths on the Brazil Margin (Mangini et al., 2010). We find no evidence in the southwestern Atlantic of large deglacial Δ<span class="hlt">14</span><span class="hlt">C</span> anomalies like those observed in the high latitude North Atlantic (Thornalley et al., 2011). When our results are paired with those from the South Pacific (De Pol-Holz et al., 2010; Rose et al., 2010), it appears AAIW did not carry a highly <span class="hlt">14</span><span class="hlt">C</span>- depleted signal during the deglaciation. Another source of carbon is apparently required to explain the intermediate-depth Δ<span class="hlt">14</span><span class="hlt">C</span> anomalies in the North Atlantic, Indian, and Pacific Oceans.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70036384','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70036384"><span id="translatedtitle">Assessing open-system behavior of <span class="hlt">14</span><span class="hlt">C</span> in terrestrial gastropod shells</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Rech, J.A.; Pigati, J.S.; Lehmann, S.B.; McGimpsey, C.N.; Grimley, D.A.; Nekola, J.C.</p> <p>2011-01-01</p> <p>In order to assess open-system behavior of radiocarbon in fossil gastropod shells, we measured the <span class="hlt">14</span><span class="hlt">C</span> activity on 10 aliquots of shell material recovered from Illinoian (~190-130 ka) and pre-Illinoian (~800 ka) loess and lacustrine deposits in the Midwestern USA. Eight of the 10 aliquots yielded measurable <span class="hlt">14</span><span class="hlt">C</span> activities that ranged from 0.25 to 0.53 percent modern carbon (pMC), corresponding to apparent <span class="hlt">14</span><span class="hlt">C</span> ages between 48.2 and 42.1 ka. This small level of open-system behavior is common in many materials that are used for <span class="hlt">14</span><span class="hlt">C</span> dating (e.g. charcoal), and typically sets the upper practical limit of the technique. Two aliquots of gastropod shells from the Illinoian-aged Petersburg Silt (Petersburg Section) in central Illinois, USA, however, yielded elevated <span class="hlt">14</span><span class="hlt">C</span> activities of 1.26 and 1.71 pMC, which correspond to apparent <span class="hlt">14</span><span class="hlt">C</span> ages of 35.1 and 32.7 ka. Together, these results suggest that while many fossil gastropods shells may not suffer from major (>1%) open-system problems, this is not always the case. We then examined the mineralogy, trace element chemistry, and physical characteristics of a suite of fossil and modern gastropod shells to identify the source of contamination in the Petersburg shells and assess the effectiveness of these screening techniques at identifying samples suitable for <span class="hlt">14</span><span class="hlt">C</span> dating. Mineralogical (XRD) and trace element analyses were inconclusive, which suggests that these techniques are not suitable for assessing open-system behavior in terrestrial gastropod shells. Analysis with scanning electron microscopy (SEM), however, identified secondary mineralization (calcium carbonate) primarily within the inner whorls of the Petersburg shells. This indicates that SEM examination, or possibly standard microscope examination, of the interior of gastropod shells should be used when selecting fossil gastropod shells for <span class="hlt">14</span><span class="hlt">C</span> dating. ?? 2011 by the Arizona Board of Regents on behalf of the University of Arizona.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://sev.lternet.edu/~jnekola/nekola%20pdf/rc-53-325-335.pdf','USGSPUBS'); return false;" href="http://sev.lternet.edu/~jnekola/nekola%20pdf/rc-53-325-335.pdf"><span id="translatedtitle">Assessing open-system behavior of <span class="hlt">14</span><span class="hlt">C</span> in terrestrial gastropod shells</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Rech, Jason A.; Pigati, Jeffrey S.; Lehmann, Sophie B.; McGimpsey, Chelsea N.; Grimley, David A.; Nekola, Jeffrey C.</p> <p>2011-01-01</p> <p>In order to assess open-system behavior of radiocarbon in fossil gastropod shells, we measured the <span class="hlt">14</span><span class="hlt">C</span> activity on 10 aliquots of shell material recovered from Illinoian (~190-130 ka) and pre-Illinoian (~800 ka) loess and lacustrine deposits in the Midwestern USA. Eight of the 10 aliquots yielded measurable <span class="hlt">14</span><span class="hlt">C</span> activities that ranged from 0.25 to 0.53 percent modern carbon (pMC), corresponding to apparent <span class="hlt">14</span><span class="hlt">C</span> ages between 48.2 and 42.1 ka. This small level of open-system behavior is common in many materials that are used for <span class="hlt">14</span><span class="hlt">C</span> dating (e.g. charcoal), and typically sets the upper practical limit of the technique. Two aliquots of gastropod shells from the Illinoian-aged Petersburg Silt (Petersburg Section) in central Illinois, USA, however, yielded elevated <span class="hlt">14</span><span class="hlt">C</span> activities of 1.26 and 1.71 pMC, which correspond to apparent <span class="hlt">14</span><span class="hlt">C</span> ages of 35.1 and 32.7 ka. Together, these results suggest that while many fossil gastropods shells may not suffer from major (>1%) open-system problems, this is not always the case. We then examined the mineralogy, trace element chemistry, and physical characteristics of a suite of fossil and modern gastropod shells to identify the source of contamination in the Petersburg shells and assess the effectiveness of these screening techniques at identifying samples suitable for <span class="hlt">14</span><span class="hlt">C</span> dating. Mineralogical (XRD) and trace element analyses were inconclusive, which suggests that these techniques are not suitable for assessing open-system behavior in terrestrial gastropod shells. Analysis with scanning electron microscopy (SEM), however, identified secondary mineralization (calcium carbonate) primarily within the inner whorls of the Petersburg shells. This indicates that SEM examination, or possibly standard microscope examination, of the interior of gastropod shells should be used when selecting fossil gastropod shells for <span class="hlt">14</span><span class="hlt">C</span> dating.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/1428885','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/1428885"><span id="translatedtitle"><span class="hlt">14</span><span class="hlt">C</span> release from a Soviet-designed pressurized water reactor nuclear power plant.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Uchrin, G; Csaba, E; Hertelendi, E; Ormai, P; Barnabas, I</p> <p>1992-12-01</p> <p>The Paks Nuclear Power Plant in Hungary runs with four pressurized water reactors, each of 440-MWe capacity. Sampling systems have been developed and used to determine the <span class="hlt">14</span><span class="hlt">C</span> of various chemical forms (14CO2, 14CO, 14CnHm) in the airborne releases. The average normalized yearly discharge rates for the time period 1988-1991 are equal to 0.77 TBq GWe-1 y-1 for hydrocarbons and 0.05 TBq GWe-1 y-1 for CO2. The contribution of 14CO was less than 0.5% of the total emission. The <span class="hlt">14</span><span class="hlt">C</span> discharge rate is estimated to be four times higher than the corresponding mean data of Western European pressurized water reactors. The calculated effective dose equivalent to individuals living in the vicinity of the power plant, due to <span class="hlt">14</span><span class="hlt">C</span> release, was 0.64 microSv in 1991 while the effective dose equivalent due to the natural <span class="hlt">14</span><span class="hlt">C</span> level was 15 microSv y-1. The long-term global impact of the <span class="hlt">14</span><span class="hlt">C</span> release in the operational period of the plant (1982-1991) was 1,270 man-Sv. The <span class="hlt">14</span><span class="hlt">C</span> excess in the environmental air has been measured since 1989 by taking biweekly samples at a distance of 1.7 km from the nuclear power plant. The long-term average of radiocarbon excess coming from the power plant was 2 mBq m-3. The local <span class="hlt">14</span><span class="hlt">C</span> deposition was followed by tree ring analysis, too. No <span class="hlt">14</span><span class="hlt">C</span> increase higher than the uncertainty of the measurement (four per thousand = 0.17 mBq m-3) was observed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23545187','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23545187"><span id="translatedtitle">Fate of (<span class="hlt">14</span>)<span class="hlt">C</span>-organic pollutant residues in composted sludge after application to soil.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Haudin, Claire-Sophie; Zhang, Yuhai; Dumény, Valérie; Lashermes, Gwenaëlle; Bergheaud, Valérie; Barriuso, Enrique; Houot, Sabine</p> <p>2013-08-01</p> <p>Organic micropollutants may be present in biosolids, leading to soil contamination when they are recycled in agriculture. A sludge spiked with (<span class="hlt">14</span>)<span class="hlt">C</span>-labelled glyphosate (GLY), sodium linear dodecylbenzene sulphonate (LAS), fluoranthene (FLT) or 4-n-nonylphenol (NP) was composted with green waste and the fate of the (<span class="hlt">14</span>)<span class="hlt">C</span>-micropollutant residues remaining after composting was assessed after the compost application to the soil. (<span class="hlt">14</span>)<span class="hlt">C</span>-residues were mineralised in the soil and represented after 140d 20-32% of the initial activity for LAS, 16-25% for GLY, 6-9% for FLT and 4-7% for NP. The (<span class="hlt">14</span>)<span class="hlt">C</span>-residues at the end of composting that could not be extracted with methanol or ammonia were minimally remobilised or even increased for FLT. After 140d, non-extractable residues represented 38-52% of all of the (<span class="hlt">14</span>)<span class="hlt">C</span>-residues remaining in the soil for FLT, 50-67% for GLY, 91-92% for NP and 94-97% for LAS and in most cases, less than 1% of the (<span class="hlt">14</span>)<span class="hlt">C</span>-residues were water soluble, suggesting a low direct availability for leaching and microbial or plant assimilation. FLT was identified as the main compound among the methanol-extractable (<span class="hlt">14</span>)<span class="hlt">C</span>-residues that may be potentially available. The fate of the (<span class="hlt">14</span>)<span class="hlt">C</span>-organic pollutant residues in composts after application to soil could be assessed through a sequential chemical extraction scheme and depended on the chemical nature of the pollutant.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/972404','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/972404"><span id="translatedtitle">Seasonally Resolved Surface Water (delta)<span class="hlt">14</span><span class="hlt">C</span> Variability in the Lombok Strait: A Coralline Perspective</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Guilderson, T P; Fallon, S J; Moore, M D; Schrag, D P; Charles, C D</p> <p>2008-04-23</p> <p>We have explored surface water mixing in the Lombok Strait through a {approx}bimonthly resolved surface water {Delta}{sup <span class="hlt">14</span>}<span class="hlt">C</span> time-series reconstructed from a coral in the Lombok Strait that spans 1937 through 1990. The prebomb surface water {Delta}{sup <span class="hlt">14</span>}<span class="hlt">C</span> average is -60.5{per_thousand} and individual samples range from -72{per_thousand} to 134{per_thousand}. The annual average post-bomb maximum occurs in 1973 and is 122{per_thousand}. The timing of the post-bomb maximum is consistent with a primary subtropical source for the surface waters in the Indonesian Seas. During the post-bomb period the coral records regular seasonal cycles of 5-20{per_thousand}. Seasonal high {Delta}{sup <span class="hlt">14</span>}<span class="hlt">C</span> occur during March-May (warm, low salinity), and low {Delta}{sup <span class="hlt">14</span>}<span class="hlt">C</span> occur in September (cool, higher salinity). The {Delta}{sup <span class="hlt">14</span>}<span class="hlt">C</span> seasonality is coherent and in phase with the seasonal {Delta}{sup <span class="hlt">14</span>}<span class="hlt">C</span> cycle observed in Makassar Strait. We estimate the influence of high {Delta}{sup <span class="hlt">14</span>}<span class="hlt">C</span> Makassar Strait (North Pacific) water flowing through the Lombok Strait using a two endmember mixing model and the seasonal extremes observed at the two sites. The percentage of Makassar Strait water varies between 16 and 70%, and between 1955 and 1990 it averages 40%. During La Nina events there is a higher percentage of Makassar Strait (high {Delta}{sup <span class="hlt">14</span>}<span class="hlt">C</span>) water in the Lombok Strait.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23545187','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23545187"><span id="translatedtitle">Fate of (<span class="hlt">14</span>)<span class="hlt">C</span>-organic pollutant residues in composted sludge after application to soil.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Haudin, Claire-Sophie; Zhang, Yuhai; Dumény, Valérie; Lashermes, Gwenaëlle; Bergheaud, Valérie; Barriuso, Enrique; Houot, Sabine</p> <p>2013-08-01</p> <p>Organic micropollutants may be present in biosolids, leading to soil contamination when they are recycled in agriculture. A sludge spiked with (<span class="hlt">14</span>)<span class="hlt">C</span>-labelled glyphosate (GLY), sodium linear dodecylbenzene sulphonate (LAS), fluoranthene (FLT) or 4-n-nonylphenol (NP) was composted with green waste and the fate of the (<span class="hlt">14</span>)<span class="hlt">C</span>-micropollutant residues remaining after composting was assessed after the compost application to the soil. (<span class="hlt">14</span>)<span class="hlt">C</span>-residues were mineralised in the soil and represented after 140d 20-32% of the initial activity for LAS, 16-25% for GLY, 6-9% for FLT and 4-7% for NP. The (<span class="hlt">14</span>)<span class="hlt">C</span>-residues at the end of composting that could not be extracted with methanol or ammonia were minimally remobilised or even increased for FLT. After 140d, non-extractable residues represented 38-52% of all of the (<span class="hlt">14</span>)<span class="hlt">C</span>-residues remaining in the soil for FLT, 50-67% for GLY, 91-92% for NP and 94-97% for LAS and in most cases, less than 1% of the (<span class="hlt">14</span>)<span class="hlt">C</span>-residues were water soluble, suggesting a low direct availability for leaching and microbial or plant assimilation. FLT was identified as the main compound among the methanol-extractable (<span class="hlt">14</span>)<span class="hlt">C</span>-residues that may be potentially available. The fate of the (<span class="hlt">14</span>)<span class="hlt">C</span>-organic pollutant residues in composts after application to soil could be assessed through a sequential chemical extraction scheme and depended on the chemical nature of the pollutant. PMID:23545187</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6975626','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6975626"><span id="translatedtitle">Extraction of /sup <span class="hlt">14</span>/<span class="hlt">C</span>-labeled photosynthate from aquatic plants with dimethyl sulfoxide (DMSO)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Filbin, G.J.; Hough, R.A.</p> <p>1984-03-01</p> <p>DMSO was tested as a solvent to extract /sup <span class="hlt">14</span>/<span class="hlt">C</span>-labeled photosynthate from three species of aquatic plants in photosynthesis measurements and compared with the dry oxidation method for plant radioassay. Extraction efficiency was in the range of 96-99% of fixed /sup <span class="hlt">14</span>/<span class="hlt">C</span>, and precision was comparable to, or better than, that obtained with dry oxidation. The method is simple and inexpensive, and for fresh tissue the same sample extracts can be used for chlorophyll analyses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/6433513','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/6433513"><span id="translatedtitle">Disposition of [<span class="hlt">14</span><span class="hlt">C</span>]methyl bromide in Fischer-344 rats after oral or intraperitoneal administration.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Medinsky, M A; Bond, J A; Dutcher, J S; Birnbaum, L S</p> <p>1984-09-14</p> <p>Methyl bromide is used as a disinfectant to fumigate soil. The intent of our study was to determine the disposition of methyl bromide following a single acute administration. Male Fischer-344 rats were given 250 mumol of [<span class="hlt">14</span><span class="hlt">C</span>] methyl bromide/kg body wt by either oral or i.p. administration. Urine, feces and expired air were collected and at the end of 72 h the rats were sacrificed and tissues analyzed to determine <span class="hlt">14</span><span class="hlt">C</span> excretion and tissue distribution. After i.p. administration of methyl bromide, the dominant route of excretion was exhalation of 14CO2, with 46% of the dose exhaled as 14CO2. In contrast, urinary excretion of <span class="hlt">14</span><span class="hlt">C</span> was the major route of elimination (43% of the dose) when methyl bromide was given orally. Very little of the <span class="hlt">14</span><span class="hlt">C</span> appeared in the feces (less than 3% of the dose) regardless of route of administration. In rats with bile duct cannulations, 46% of an oral dose appeared in the bile over a 24-h period. Collection of bile significantly decreased the exhalation of 14CO2 and <span class="hlt">14</span><span class="hlt">C</span> excreted in urine compared to controls. At 72 h after oral or i.p. administration, 14-17% of the <span class="hlt">14</span><span class="hlt">C</span> remained in the rats, with liver and kidney being the major organs of retention. Results indicate that route of administration can affect the pathways for excretion. In addition, excretion of <span class="hlt">14</span><span class="hlt">C</span> in bile, coupled with the low levels of radioactivity found in the feces, indicates that reabsorption of biliary metabolites from the gut plays a significant role in the disposition of [<span class="hlt">14</span><span class="hlt">C</span>] methyl bromide.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6648487','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6648487"><span id="translatedtitle">( sup <span class="hlt">14</span> <span class="hlt">C</span>)urea breath test for diagnosis of Helicobacter pylori</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ormand, J.E.; Talley, N.J.; Carpenter, H.A.; Shorter, R.G.; Conley, C.R.; Wilson, W.R.; DiMagno, E.P.; Zinsmeister, A.R.; Phillips, S.F. )</p> <p>1990-07-01</p> <p>H. pylori is a potent urease producer, a characteristic that has been exploited in the development of the (<span class="hlt">14</span><span class="hlt">C</span>)- and (13C)urea breath tests. The prevalence of H. pylori infection also is known to increase with advancing age; however, the individual patient's age has not routinely been considered when interpreting urea breath test results. The aim of this study was to validate a short, age-adjusted (<span class="hlt">14</span><span class="hlt">C</span>)urea breath test for use in diagnosing H. pylori infections. Forty-one subjects (28 volunteers, 13 patients) underwent esophagogastroduodenoscopy with biopsies. Subjects were defined as being H. pylori-positive if histology or culture was positive. In addition, all subjects completed a 120-min (<span class="hlt">14</span><span class="hlt">C</span>)urea breath test. A logistic regression analysis adjusting for age was used to estimate the probability of H. pylori positivity as a function of the <span class="hlt">14</span><span class="hlt">C</span> values generated. Sixteen subjects were H. pylori-positive, and 25 were H. pylori-negative. The <span class="hlt">14</span><span class="hlt">C</span> values generated between 15 and 80 min were found to be equally predictive in identifying H. pylori-positive subjects. Advancing age was associated with a higher probability of H. pylori-positivity. By taking advantage of the statistical probabilities, older patients could be accurately diagnosed with H. pylori at lower <span class="hlt">14</span><span class="hlt">C</span> values. We found that (<span class="hlt">14</span><span class="hlt">C</span>)urea breath test to be both a sensitive and specific test that can be abbreviated to a 30-min examination (total test time). Moreover, our mathematical model indicates that a patient's age should be considered in order to optimize interpretation of the (<span class="hlt">14</span><span class="hlt">C</span>)urea breath test, although further observations are needed to confirm this model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000NIMPB.172..939G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000NIMPB.172..939G"><span id="translatedtitle">AMS studies of the long-term turnover of <span class="hlt">14</span><span class="hlt">C</span>-labelled fat in man</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gunnarsson, M.; Mattsson, S.; Stenström, K.; Leide-Svegborn, S.; Erlandsson, B.; Faarinen, M.; Hellborg, R.; Kiisk, M.; Nilsson, L.-E.; Nosslin, B.; Persson, P.; Skog, G.; Åberg, M.</p> <p>2000-10-01</p> <p>To estimate the biokinetics of <span class="hlt">14</span><span class="hlt">C</span>-labelled fatty acids and the associated radiation absorbed dose to man, long-term retention of <span class="hlt">14</span><span class="hlt">C</span> from oral intake of glycerol tri[1- <span class="hlt">14</span><span class="hlt">C</span>]oleate (triolein) has been studied using accelerator mass spectrometry (AMS). As a complement to earlier reported data for three individuals, we present here results for one person from measurements up to 4.6 yr after administration, now also including <span class="hlt">14</span><span class="hlt">C</span>-levels in fat, muscle and bone. In this subject, a total of 44% of the administered activity was recovered in the exhaled air. Fasting increased the exhalation of <span class="hlt">14</span><span class="hlt">C</span>. The "excess" 14CO2 due to fasting had a half-life of about 400 d. AMS measurements on fat, muscle and bone biopsies taken from the same subject 4.5 yr after ingestion indicated that a small fraction of the administered activity was still present in fat. Also, bone tissue had a higher <span class="hlt">14</span><span class="hlt">C</span> specific activity than the current environmental level. No significantly increased level was found in the muscle sample.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23401563','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23401563"><span id="translatedtitle">Lack of tissue renewal in human adult Achilles tendon is revealed by nuclear bomb (<span class="hlt">14</span>)<span class="hlt">C</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Heinemeier, Katja Maria; Schjerling, Peter; Heinemeier, Jan; Magnusson, Stig Peter; Kjaer, Michael</p> <p>2013-05-01</p> <p>Tendons are often injured and heal poorly. Whether this is caused by a slow tissue turnover is unknown, since existing data provide diverging estimates of tendon protein half-life that range from 2 mo to 200 yr. With the purpose of determining life-long turnover of human tendon tissue, we used the (<span class="hlt">14</span>)<span class="hlt">C</span> bomb-pulse method. This method takes advantage of the dramatic increase in atmospheric levels of (<span class="hlt">14</span>)<span class="hlt">C</span>, produced by nuclear bomb tests in 1955-1963, which is reflected in all living organisms. Levels of (<span class="hlt">14</span>)<span class="hlt">C</span> were measured in 28 forensic samples of Achilles tendon core and 4 skeletal muscle samples (donor birth years 1945-1983) with accelerator mass spectrometry (AMS) and compared to known atmospheric levels to estimate tissue turnover. We found that Achilles tendon tissue retained levels of (<span class="hlt">14</span>)<span class="hlt">C</span> corresponding to atmospheric levels several decades before tissue sampling, demonstrating a very limited tissue turnover. The tendon concentrations of (<span class="hlt">14</span>)<span class="hlt">C</span> approximately reflected the atmospheric levels present during the first 17 yr of life, indicating that the tendon core is formed during height growth and is essentially not renewed thereafter. In contrast, (<span class="hlt">14</span>)<span class="hlt">C</span> levels in muscle indicated continuous turnover. Our observation provides a fundamental premise for understanding tendon function and pathology, and likely explains the poor regenerative capacity of tendon tissue.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/14708776','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14708776"><span id="translatedtitle">Direct dating of archaeological pottery by compound-specific <span class="hlt">14</span><span class="hlt">C</span> analysis of preserved lipids.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Stott, Andrew W; Berstan, Robert; Evershed, Richard P; Bronk-Ramsey, Christopher; Hedges, Robert E M; Humm, Martin J</p> <p>2003-10-01</p> <p>A methodology is described demonstrating the utility of the compound-specific <span class="hlt">14</span><span class="hlt">C</span> technique as a direct means of dating archaeological pottery. The method uses automated preparative capillary gas chromatography employing wide-bore capillary columns to isolate individual compounds from lipid extracts of archaeological potsherds in high purity (>95%) and amounts (>200 microg) sufficient for radiocarbon dating using accelerator mass spectrometry (AMS). A protocol was developed and tested on n-alkanes and n-carboxylic acids possessing a broad range of <span class="hlt">14</span><span class="hlt">C</span> ages. Analytical blanks and controls allowed background <span class="hlt">14</span><span class="hlt">C</span> measurements to be assessed and potential sources of errors to be detected, i.e., contamination with modern or dead <span class="hlt">14</span><span class="hlt">C</span>, isotopic fraction effects, etc. A "Russian doll" method was developed to transfer isolated target compounds onto tin powder/capsules prior to combustion and AMS analyses. The major advantage of the compound-specific technique is that <span class="hlt">14</span><span class="hlt">C</span> dates obtained for individual compounds can be directly linked to the commodities processed in the vessels during their use, e.g., animal fats. The compound-specific <span class="hlt">14</span><span class="hlt">C</span> dating protocol was validated on a suite of ancient pottery whose predicted ages spanned a 5000-year date range. Initial results indicate that meaningful correlations can be obtained between the predicted date of pottery and that of the preserved lipids. These findings constitute an important step forward to the direct dating of archaeological pottery.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20390940','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20390940"><span id="translatedtitle">Fate of <span class="hlt">14</span><span class="hlt">C</span>-ethyl prothiofos insecticide in canola seeds and oils.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Abdel-Gawad, Hassan; Hegazi, Bahira</p> <p>2010-02-01</p> <p>Canola plants were treated with (<span class="hlt">14</span>)<span class="hlt">C</span>- prohiofos under conditions simulating local agricultural practices. (<span class="hlt">14</span>)<span class="hlt">C</span>-residues in seeds were determined at different time intervals. At harvest time about 32 % of (<span class="hlt">14</span>)<span class="hlt">C</span>-activity was associated with oil. The methanol soluble (<span class="hlt">14</span>)<span class="hlt">C</span>-residues accounted for 12 % of the total seed residues after further seeds extraction, while the cake contained about 49 % of the total residues. About 69 % of the (<span class="hlt">14</span>)<span class="hlt">C</span>-activity in the crude oil could be eliminated by simulated commercial processes locally used for oil refining. Chromatographic analysis of crude and refined oil revealed the presence of the parent compound together with three metabolites which were identified as prothiofos oxon, O-ethyl phosphorothioate and O-ethyl S-propyl phosphorothioate, besides one unknown compound. While methanol extract revealed the presence of despropylthio prothiofos and O-ethyl phosphoric acid as free metabolites acid hydrolysis of the conjugated metabolites in the methanol extract yielded 2, 4-dichlorophenole which was detected by color. When rats were fed the extracted cake for 72 hours, the bound residues were found to be bioavailable. The main excretion route was via the expired air (42 %), while the (<span class="hlt">14</span>)<span class="hlt">C</span>-residues excreted in urine and feces were 30 % and 11 %, respectively. The radioactivity detected among various organs accounted to 7.5 %.Chromatographic analysis of urine indicated the presence of prothiofos oxon, O-ethyl phosphoric acid and 2, 4-dichlorophenole as main degradation products of prothiofos in free and conjugated form.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24677225','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24677225"><span id="translatedtitle">A simple method to determine mineralization of (<span class="hlt">14</span>) <span class="hlt">C</span>-labeled compounds in soil.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Myung, Kyung; Madary, Michael W; Satchivi, Norbert M</p> <p>2014-06-01</p> <p>Degradation of organic compounds in soil is often determined by measuring the decrease of the parent compound and analyzing the occurrence of its metabolites. However, determining carbon species as end products of parent compound dissipation requires using labeled materials that allow more accurate determination of the environmental fate of the compound of interest. The current conventional closed system widely used to monitor degradation of (<span class="hlt">14</span>) <span class="hlt">C</span>-labeled compounds in soil is complex and expensive and requires a specialized apparatus and facility. In the present study, the authors describe a simple system that facilitates measurement of mineralization of (<span class="hlt">14</span>) <span class="hlt">C</span>-labeled compounds applied to soil samples. In the system, soda lime pellets to trap mineralized (<span class="hlt">14</span>) <span class="hlt">C</span>-carbon species, including carbon dioxide, were placed in a cup, which was then inserted above the treated soil sample in a tube. Mineralization of [(<span class="hlt">14</span>) <span class="hlt">C</span>]2,4-D applied to soil samples in the simple system was compared with that in the conventional system. The simple system provided an equivalent detection of (<span class="hlt">14</span>) <span class="hlt">C</span>-carbon species mineralized from the parent compound. The results demonstrate that this cost- and space-effective simple system is suitable for examining degradation and mineralization of (<span class="hlt">14</span>) <span class="hlt">C</span>-labeled compounds in soil and could potentially be used to investigate their mineralization in other biological matrices.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5643929','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5643929"><span id="translatedtitle">Metabolism of (2-<span class="hlt">14</span><span class="hlt">C</span>)acetate and its use in assessing hepatic Krebs cycle activity and gluconeogenesis</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Schumann, W.C.; Magnusson, I.; Chandramouli, V.; Kumaran, K.; Wahren, J.; Landau, B.R. )</p> <p>1991-04-15</p> <p>To examine the fate of the carbons of acetate and to evaluate the usefulness of labeled acetate in assessing intrahepatic metabolic processes during gluconeogenesis, (2-<span class="hlt">14</span><span class="hlt">C</span>)acetate, (2-<span class="hlt">14</span><span class="hlt">C</span>)ethanol, and (1-<span class="hlt">14</span><span class="hlt">C</span>)ethanol were infused into normal subjects fasted 60 h and given phenyl acetate. Distributions of <span class="hlt">14</span><span class="hlt">C</span> in the carbons of blood glucose and glutamate from urinary phenylacetylglutamine were determined. With (2-<span class="hlt">14</span><span class="hlt">C</span>)acetate and (2-<span class="hlt">14</span><span class="hlt">C</span>)ethanol, carbon 1 of glucose had about twice as much <span class="hlt">14</span><span class="hlt">C</span> as carbon 3. Carbon 2 of glutamate had about twice as much <span class="hlt">14</span><span class="hlt">C</span> as carbon 1 and one-half to one-third as much as carbon 4. There was only a small amount in carbon 5. These distributions are incompatible with the metabolism of (2-<span class="hlt">14</span><span class="hlt">C</span>)acetate being primarily in liver. Therefore, (2-<span class="hlt">14</span><span class="hlt">C</span>)acetate cannot be used to study Krebs cycle metabolism in liver and in relationship to gluconeogenesis, as has been done. The distributions can be explained by: (a) fixation of 14CO2 from (2-<span class="hlt">14</span><span class="hlt">C</span>)acetate in the formation of the <span class="hlt">14</span><span class="hlt">C</span>-labeled glucose and glutamate in liver and (b) the formation of <span class="hlt">14</span><span class="hlt">C</span>-labeled glutamate in a second site, proposed to be muscle. (1,3-<span class="hlt">14</span><span class="hlt">C</span>)Acetone formation from the (2-<span class="hlt">14</span><span class="hlt">C</span>)acetate does not contribute to the distributions, as evidenced by the absence of <span class="hlt">14</span><span class="hlt">C</span> in carbons 2-4 of glutamate after (1-<span class="hlt">14</span><span class="hlt">C</span>)ethanol administration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/812183','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/812183"><span id="translatedtitle">Laboratory Experiments to Evaluate Diffusion of <span class="hlt">14</span><span class="hlt">C</span> into Nevada Test Site Carbonate Aquifer Matrix</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ronald L. Hershey; William Howcroft; Paul W. Reimus</p> <p>2003-03-01</p> <p>Determination of groundwater flow velocities at the Nevada Test Site is important since groundwater is the principal transport medium of underground radionuclides. However, <span class="hlt">14</span><span class="hlt">C</span>-based groundwater velocities in the carbonate aquifers of the Nevada Test Site are several orders of magnitude slower than velocities derived from the Underground Test Area regional numerical model. This discrepancy has been attributed to the loss or retardation of <span class="hlt">14</span><span class="hlt">C</span> from groundwater into the surrounding aquifer matrix making <span class="hlt">14</span><span class="hlt">C</span>-based groundwater ages appear much older. Laboratory experiments were used to investigate the retardation of <span class="hlt">14</span><span class="hlt">C</span> in the carbonate aquifers at the Nevada Test Site. Three sets of experiments were conducted evaluating the diffusion of <span class="hlt">14</span><span class="hlt">C</span> into the carbonate aquifer matrix, adsorption and/or isotopic exchange onto the pore surfaces of the carbonate matrix, and adsorption and/or isotopic exchange onto the fracture surfaces of the carbonate aquifer. Experimental results a nd published aquifer matrix and fracture porosities from the Lower Carbonate Aquifer were applied to a <span class="hlt">14</span><span class="hlt">C</span> retardation model. The model produced an extremely wide range of retardation factors because of the wide range of published aquifer matrix and fracture porosities (over three orders of magnitude). Large retardation factors suggest that groundwater with very little measured <span class="hlt">14</span><span class="hlt">C</span> activity may actually be very young if matrix porosity is large relative to the fracture porosity. Groundwater samples collected from highly fractured aquifers with large effective fracture porosities may have relatively small correction factors, while samples from aquifers with a few widely spaced fractures may have very large correction factors. These retardation factors were then used to calculate groundwater velocities from a proposed flow path at the Nevada Test Site. The upper end of the range of <span class="hlt">14</span><span class="hlt">C</span> correction factors estimated groundwater velocities that appear to be at least an order of magnitude too high compared</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6219362','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6219362"><span id="translatedtitle">Measuring chlorophyll. cap alpha. and /sup <span class="hlt">14</span>/<span class="hlt">C</span>-labeled photosynthate in aquatic angiosperms by the use of a tissue solubilizer. [/sup <span class="hlt">14</span>/<span class="hlt">C</span>-labelled photosynthate</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Beer, S.; Stewart, A.J.; Wetzel, R.G.</p> <p>1982-01-01</p> <p>A compound that quantitatively correlated with chlorophyll ..cap alpha.. could be measured fluorometrically in the extracts of leaves of three aquatic angiosperms (Myriophyllum heterophyllum Michx., Potamogeton crispus L., Elodea canadensis Michx.) treated with the tissue solubilizer BTS-450. Fluorescent characteristics of the solubilized plant tissues were stable for several weeks in the dark at temperatures up to 60/sup 0/C but rapidly degraded in sunlight or when acidified. /sup <span class="hlt">14</span>/<span class="hlt">C</span>-Labeled photosynthate, which had been fixed by leaf discs during 1- to 10-hour exposure to H/sup 14/CO/sub 3/, was also readily extracted by the tissue solubilizer. Solubilizer extraction can, therefore, be used to determine both chlorophyll ..cap alpha.. content and /sup <span class="hlt">14</span>/<span class="hlt">C</span> incorporation rates in the same leaf sample. The method is practical, because no grinding is required, the fluorescent characteristics of the extracts are stable, and analyses can be performed with very little plant material (about 3 milligrams).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6787784','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6787784"><span id="translatedtitle">Persistence of the herbicides (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)chlorsulfuron and (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)metsulfuron methyl in prairie soils under laboratory conditions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Smith, A.E.</p> <p>1986-11-01</p> <p>Metsulfuron methyl, whose structure is closely related to that of chlorsulfuron, is currently being evaluated on the Canadian prairies as a postemergence treatment for the control of broadleaf weeds in cereal crops, in non-crop land and for brush control. Although applied postemergence, some of the herbicide will come into contact with the soil making it necessary to determine the fate of metsulfuron methyl in the soil. These studies were undertaken to investigate the rate of breakdown and the fate of (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)metsulfuron methyl in three soils under laboratory conditions where no leaching could occur. The rate of breakdown of (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)chlorsulfuron was also investigated in one of the soils.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6257823','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6257823"><span id="translatedtitle">The effects of the oral administration of fish oil concentrate on the release and the metabolism of (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)arachidonic acid and (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)eicosapentaenoic acid by human platelets</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hirai, A.; Terano, T.; Hamazaki, T.; Sajiki, J.; Kondo, S.; Ozawa, A.; Fujita, T.; Miyamoto, T.; Tamura, Y.; Kumagai, A.</p> <p>1982-11-01</p> <p>It has been suggested by several investigators that eicosapentaenoic acid (C20:5 omega 3, EPA) might have anti-thrombotic effects. In this experiment, the effect of the oral administration of EPA rich fish oil concentrate on platelet aggregation and the release and the metabolism of (/sup 1 -<span class="hlt">14</span>/<span class="hlt">C</span>)arachidonic acid and ((U)-/sup <span class="hlt">14</span>/<span class="hlt">C</span>)eicosapentaenoic acid by human platelets was studied. Eight healthy male subjects ingested 18 capsules of fish oil concentrate (EPA 1.4 g) per day for 4 weeks. Plasma and platelet concentrations of EPA markedly increased, while those of arachidonic acid (C20:4 omega 6, AA) and docosahexaenoic acid (C22:6 omega 3, DHA) did not change. Platelet aggregation induced by collagen and ADP was reduced. Collagen induced (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)thromboxane B2 (TXB2) formation from (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)AA prelabeled platelets decreased. There was no detectable formation of (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)TXB3 from (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)EPA prelabeled platelets, and the conversion of exogenous (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)EPA to (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)TXB3 was lower than that of (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)AA to (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)TXB2. The release of (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)AA from (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)AA prelabeled platelets by collagen was significantly decreased. These observations raise the possibility that the release of arachidonic acid from platelet lipids might be affected by the alteration of EPA content in platelets.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhRvC..93d5803W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvC..93d5803W"><span id="translatedtitle">Accelerator mass spectrometry measurements of the 13C (n ,γ )<span class="hlt">14</span><span class="hlt">C</span> and 14N(n ,p )<span class="hlt">14</span><span class="hlt">C</span> cross sections</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wallner, A.; Bichler, M.; Buczak, K.; Dillmann, I.; Käppeler, F.; Karakas, A.; Lederer, C.; Lugaro, M.; Mair, K.; Mengoni, A.; Schätzel, G.; Steier, P.; Trautvetter, H. P.</p> <p>2016-04-01</p> <p>The technique of accelerator mass spectrometry (AMS), offering a complementary tool for sensitive studies of key reactions in nuclear astrophysics, was applied for measurements of the 13C (n ,γ )<span class="hlt">14</span><span class="hlt">C</span> and the 14N(n ,p )<span class="hlt">14</span><span class="hlt">C</span> cross sections, which act as a neutron poison in s -process nucleosynthesis. Solid samples were irradiated at Karlsruhe Institute of Technology with neutrons closely resembling a Maxwell-Boltzmann distribution for k T =25 keV, and also at higher energies between En=123 and 182 keV. After neutron irradiation the produced amount of <span class="hlt">14</span><span class="hlt">C</span> in the samples was measured by AMS at the Vienna Environmental Research Accelerator (VERA) facility. For both reactions the present results provide important improvements compared to previous experimental data, which were strongly discordant in the astrophysically relevant energy range and missing for the comparably strong resonances above 100 keV. For 13C (n ,γ ) we find a four times smaller cross section around k T =25 keV than a previous measurement. For 14N(n ,p ), the present data suggest two times lower cross sections between 100 and 200 keV than had been obtained in previous experiments and data evaluations. The effect of the new stellar cross sections on the s process in low-mass asymptotic giant branch stars was studied for stellar models of 2 M⊙ initial mass, and solar and 1 /10th solar metallicity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1054663','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1054663"><span id="translatedtitle">Changes in the <span class="hlt">14</span><span class="hlt">C</span>-Labeled Cell Wall Components with Chase Time after Incorporation of UDP[<span class="hlt">14</span><span class="hlt">C</span>]Glucose by Intact Cotton Fibers 1</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Dugger, W. M.; Palmer, Raymond L.</p> <p>1988-01-01</p> <p>Intact, in vitro-grown cotton fibers will incorporate [<span class="hlt">14</span><span class="hlt">C</span>]glucose from externally supplied UDP[<span class="hlt">14</span><span class="hlt">C</span>]glucose into a variety of cell wall components including cellulose; this labeled fraction will continue to increase up to 4 hours chase time. In the fraction soluble in hot water there was no significant change in total label; however, the largest fraction after the 30 minute pulse with UDP[<span class="hlt">14</span><span class="hlt">C</span>]glucose was chloroform-methanol soluble (70%) and showed a significant decrease with chase. The lipids that make up about 85% of this fraction were identified by TLC as steryl glucosides, acylated steryl glucosides, and glucosyl-phosphoryl-polyprenol. Following the pulse, the loss of label from acylated steryl glucosides and glucosylphophoryl-polyprenol was almost complete within 2 hours of chase; steryl glucosides made up about 85% of the fraction at that chase time. The total loss in the lipid fraction (about 100 picomoles per milligram dry weight of fiber) with chase times of 4 hours approximates the total gain in the total glucans. PMID:16666066</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24944798','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24944798"><span id="translatedtitle">Effect of cytochalasin B on 3-O-[(<span class="hlt">14</span>)<span class="hlt">C</span>]-methyl-D-glucose or D-[U-(<span class="hlt">14</span>)<span class="hlt">C</span>]glucose handling by BRIN-BD11 cells.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cetik, Sibel; Rzajeva, Aigun; Malaisse, Willy J; Sener, Abdullah</p> <p>2014-07-01</p> <p>The present study aimed to investigate the effects of cytochalasin B (20 μM) on the uptake of 3-O-[(<span class="hlt">14</span>)<span class="hlt">C</span>]-methyl-D-glucose or D-[U-(<span class="hlt">14</span>)<span class="hlt">C</span>]glucose (8.3 mM each) by BRIN-BD11 cells. Taking into account the distribution space of tritiated water ((3)HOH), which was unexpectedly increased shortly after exposure of the cells to cytochalasin B and then progressively returned to its control values, and that of L-[1-(<span class="hlt">14</span>)<span class="hlt">C</span>]glucose, used as an extracellular marker, it was demonstrated that cytochalasin B caused a modest, but significant inhibition of the uptake of D-glucose and its non-metabolized analog by the BRIN-BD11 cells. These findings resemble those observed in acinar or ductal cells of the rat submaxillary gland and displayed a relative magnitude comparable to that found for the inhibition of D-glucose metabolism by cytochalasin B in purified pancreatic islet B cells. These findings reinforce the view that the primary site of action of cytochalasin B is located at the level of the plasma membrane.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015QSRv..126..140B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015QSRv..126..140B"><span id="translatedtitle">Cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> exposure ages reveal a 9.3 ka BP glacier advance and the Late Weichselian-Early Holocene glacial history of the Drangajökull region, northwest Iceland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brynjólfsson, Skafti; Schomacker, Anders; Ingólfsson, Ólafur; Keiding, Jakob K.</p> <p>2015-10-01</p> <p>We present twenty-four new cosmogenic isotope (<span class="hlt">36</span><span class="hlt">Cl</span>) surface exposure ages from erratic boulders, moraine boulders and glacially eroded bedrock that constrain the late Weichselian to Holocene glacial history of the Drangajökull region, northwest Iceland. The results suggest a topographically controlled ice sheet over the Vestfirðir (Westfjords) peninsula during the last glaciation. Cold based non-erosive sectors of the ice sheet covered most of the mountains while fjords and valleys were occupied with erosive, warm-based ice. Old<span class="hlt">36</span><span class="hlt">Cl</span> exposure ages from highlands and mountain plateaux (L8; 76.5 ka and H1; 41.6 ka) in combination with younger erratic boulders (L7; 26.2 and K1-K4; 15.0-13.8 ka) superimposed on such surfaces suggest the presence of non-erosive ice over uplands and plateaux in the Vestfirðir peninsula during the last glaciation. Glacially scoured terrain and erratic boulders yielding younger exposure ages (L1-L6; 11.3-9.1 ka and R1, R6-R7; 10.6-9.4 ka) in the lowland areas indicate that the valleys and fjords of the Vestfirðir peninsula were occupied by warm-based, dynamic ice during the last glaciation. The deglaciation of mountain Leirufjall by 26.2 ka BP suggests that ice thinning and deglaciation of some mountains and plateaux preceded any significant lateral retreat of the ice sheet. Subsequently this initial ice thinning was followed by break-up of the shelf based ice sheet off Vestfirðir about 15 ka BP. Hence, the new exposure ages suggest a stepwise asynchronous deglaciation on land, following the shelf break-up with some valleys and most of the highlands, ice free by 14-15 ka BP. The outermost moraine at the mouth of Leirufjörður is dated to 9.3 ka BP, and we suggest the moraine to be formed by a glacier re-advance in response to a cooler climate forced by the reduced Atlantic Meridional Overturning Circulation at around 9.3 ka BP. A system of moraines proximal to the 9.3 ka moraine in Leirufjörður as well as a 9.4 ka deglaciation age</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850026782','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850026782"><span id="translatedtitle">Solar modulation of cosmic ray intensity and solar flare events inferred from (<span class="hlt">14</span>)<span class="hlt">C</span> contents in dated tree rings</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fan, C. Y.; Chen, T. M.; Yun, S. X.; Dai, K. M.</p> <p>1985-01-01</p> <p>The delta <span class="hlt">14</span><span class="hlt">C</span> values in 42 rings of a white spruce grown in Mackenzie Delta was measured as a continuing effort of tracing the history of solar modulation of cosmic ray intensity. The delta <span class="hlt">14</span><span class="hlt">C</span> values in six rings were measured, in search of a <span class="hlt">14</span><span class="hlt">C</span> increase due to two large solar flares that occurred in 1942. The results are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMOS43B1823P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS43B1823P"><span id="translatedtitle">Low-level <span class="hlt">14</span><span class="hlt">C</span> methane oxidation rate measurements modified for remote field settings</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pack, M. A.; Pohlman, J.; Ruppel, C. D.; Xu, X.</p> <p>2012-12-01</p> <p>Aerobic methane oxidation limits atmospheric methane emissions from degraded subsea permafrost and dissociated methane hydrates in high latitude oceans. Methane oxidation rate measurements are a crucial tool for investigating the efficacy of this process, but are logistically challenging when working on small research vessels in remote settings. We modified a low-level <span class="hlt">14</span><span class="hlt">C</span>-CH4 oxidation rate measurement for use in the Beaufort Sea above hydrate bearing sediments during August 2012. Application of the more common 3H-CH4 rate measurement that uses 106 times more radioactivity was not practical because the R/V Ukpik cannot accommodate a radiation van. The low-level <span class="hlt">14</span><span class="hlt">C</span> measurement does not require a radiation van, but careful isolation of the <span class="hlt">14</span><span class="hlt">C</span>-label is essential to avoid contaminating natural abundance <span class="hlt">14</span><span class="hlt">C</span> measurements. We used <span class="hlt">14</span><span class="hlt">C</span>-CH4 with a total activity of 1.1 μCi, which is far below the 100 μCi permitting level. In addition, we modified field procedures to simplify and shorten sample processing. The original low-level <span class="hlt">14</span><span class="hlt">C</span>-CH4 method requires 6 steps in the field: (1) collect water samples in glass serum bottles, (2) inject <span class="hlt">14</span><span class="hlt">C</span>-CH4 into bottles, (3) incubate for 24 hours, (4) filter to separate the methanotrophic bacterial cells from the aqueous sample, (5) kill the filtrate with sodium hydroxide (NaOH), and (6) purge with nitrogen to remove unused <span class="hlt">14</span><span class="hlt">C</span>-CH4. Onshore, the <span class="hlt">14</span><span class="hlt">C</span>-CH4 respired to carbon dioxide or incorporated into cell material by methanotrophic bacteria during incubation is quantified by accelerator mass spectrometry (AMS). We conducted an experiment to test the possibility of storing samples for purging and filtering back onshore (steps 4 and 6). We subjected a series of water samples to steps 1-3 & 5, and preserved with mercuric chloride (HgCl2) instead of NaOH because HgCl2 is less likely to break down cell material during storage. The <span class="hlt">14</span><span class="hlt">C</span>-content of the carbon dioxide in samples preserved with HgCl2 and stored for up to 2 weeks was stable</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMPP21B1799L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMPP21B1799L"><span id="translatedtitle">Reconstructing the Vertical <span class="hlt">14</span><span class="hlt">C</span> Gradient of the Baja Margin during the Last Deglaciation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lindsay, C. M.; Lehman, S. J.; Marchitto, T. M.; Ortiz, J. D.; van Geen, A.</p> <p>2011-12-01</p> <p>The radiocarbon activity (Δ<span class="hlt">14</span><span class="hlt">C</span>) of the atmosphere decreased in two steps during the last deglaciation, coinciding with the well-known Heinrich 1 (H1) and Younger Dryas (YD) stadials. A leading explanation for these periods of decline involves the release of <span class="hlt">14</span><span class="hlt">C</span>-depleted carbon from a deep, isolated ocean reservoir- a mechanism that may also help to explain the deglacial rise in atmospheric CO2. Reconstructions of intermediate water Δ<span class="hlt">14</span><span class="hlt">C</span> near Baja California, Mexico (Marchitto et al., 2007 Science) and in the Arabian Sea (Bryan et al., 2010 Earth Planet. Sci. Lett.) document two intervals of extreme depletion relative to the coeval atmosphere during H1 and the YD that are interpreted as evidence of the return of this aged carbon from the deep reservoir to the upper ocean and atmosphere. Here we report on <span class="hlt">14</span><span class="hlt">C</span> measurements in additional cores from the Baja margin that expand the depth range of our observations and enable reconstruction of the vertical Δ<span class="hlt">14</span><span class="hlt">C</span> gradient. Calendar ages were determined by (1) correlation of diffuse spectral reflectance (DSR, a proxy related to local productivity) with the layer-counted age model in the GISP2 ice core and (2) correlation of raw planktic G. ruber <span class="hlt">14</span><span class="hlt">C</span> ages to new measurements in core PC08 previously studied by Marchitto et al. (2007). Together these provide a common and consistent calendar age model for margin core PCO8 (depth 705 m), core PC13 from Soledad Basin (sill depth 290 m) and margin core GC38 (depth 1270 m). In preliminary results, G. ruber Δ<span class="hlt">14</span><span class="hlt">C</span> data from PC08 exhibit a record of deglacial depletion events that is consistent with partial upward mixing of the intermediate-depth signal to the surface. Δ<span class="hlt">14</span><span class="hlt">C</span> at 1270 meters showed relatively little change during H1 and YD, indicating that anomalously depleted water did not penetrate to this depth. The vertical gradient collapsed to within observational uncertainties at the start of the Bølling-Allerød/Antarctic Climate Reversal. Taken together the results support</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.B11H0538K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.B11H0538K"><span id="translatedtitle">Carbon cycling in a complex lake: a novel use of Δ<span class="hlt">14</span><span class="hlt">C</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Keaveney, E. M.; Reimer, P. J.; Foy, R. H.</p> <p>2015-12-01</p> <p>Changing deposition chemistry, land use and climate induced impacts on hydrology will affect soil biogeochemistry and terrestrial C export and hence lake ecology with potential feedbacks for regional and global C cycling. Globally lakes bury and remineralise significant quantities of terrestrial C, and the associated flux of terrestrial C strongly influences their functioning. Primary production (autochthonous production) in lakes is based on dissolved inorganic C (DIC). DIC in alkaline lakes is partially derived from weathering of carbonaceous bedrock, a proportion of which is <span class="hlt">14</span><span class="hlt">C</span>-free. The low <span class="hlt">14</span><span class="hlt">C</span> activity yields an artificial age offset leading samples to appear hundreds to thousands of years older than their actual age. Dissolved organic carbon (DOC) and particulate organic carbon (POC) can contain terrestrial inputs. The terrestrial inputs can be labile or detrital; their age depends on their depth in catchment soil/peat stocks. We present a pilot study that uses the radiocarbon (∆<span class="hlt">14</span><span class="hlt">C</span>) method to determine the source of carbon buried in the surface sediment of Lough Erne, a humic, alkaline lake in northwest Ireland. ∆<span class="hlt">14</span><span class="hlt">C</span>, δ13C and δ15N values were measured from phytoplankton and other biota, dissolved inorganic, dissolved organic and particulate organic carbon. A novel radiocarbon method, Stepped Combustion1 was used to estimate the degree of the burial of terrestrial carbon in surface sediment. The ∆<span class="hlt">14</span><span class="hlt">C</span> values of the low temperature fractions were comparable to algal ∆<span class="hlt">14</span><span class="hlt">C</span>, while the high temperature fractions were <span class="hlt">14</span><span class="hlt">C</span>-depleted (older than bulk sediment). The ∆<span class="hlt">14</span><span class="hlt">C</span> end-member model indicated that ~64% of carbon in surface sediment was derived from detrital terrestrial carbon. The use of ∆<span class="hlt">14</span><span class="hlt">C</span> in conjunction with stepped combustion allows the quantification of the pathways of terrestrial carbon in the system, which has implications for regional and global carbon burial. 1McGeehin, J., Burr, G.S., Jull, A.J.T., Reines, D., Gosse, J., Davis, P.T., Muhs</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.8515K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.8515K"><span id="translatedtitle">Tracing terrestrial carbon: a novel application of ∆<span class="hlt">14</span><span class="hlt">C</span> in a humic lake</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Keaveney, Evelyn; Reimer, Paula J.; Foy, Robert H.</p> <p>2016-04-01</p> <p>Lakes play an important yet underrated role in global carbon cycles. Terrestrial carbon (C) is buried and/or remineralised in significant quantities, and lake function may also be affected by catchment inputs with potential feedbacks for regional and global C cycling. Changing deposition chemistry, land use and climate induced impacts on hydrology will affect soil biogeochemistry, terrestrial C export, and hence lake ecology. Autochthonous production in lakes is based on dissolved inorganic C (DIC). DIC in alkaline lakes is partially derived from weathering of carbonaceous bedrock, a proportion of which is <span class="hlt">14</span><span class="hlt">C</span>-free. The low <span class="hlt">14</span><span class="hlt">C</span> activity yields an artificial age offset leading samples to appear hundreds to thousands of years older than their actual age. Dissolved organic carbon (DOC) and particulate organic carbon (POC) can contain terrestrial inputs. The terrestrial inputs can be labile or detrital and their age depends to a first order on their depth in catchment soil/peat stocks. We present a pilot study that uses the radiocarbon (∆<span class="hlt">14</span><span class="hlt">C</span>) method to determine the source of carbon buried in the surface sediment of Lower Lough Erne, a humic, alkaline lake in northwest Ireland. ∆<span class="hlt">14</span><span class="hlt">C</span>, δ13C and δ15N values were measured from phytoplankton and other biota, dissolved inorganic, dissolved organic and particulate organic carbon. A novel radiocarbon method, Stepped Combustion1 was used to estimate the degree of the burial of terrestrial carbon in surface sediment, collected in 2011. The ∆<span class="hlt">14</span><span class="hlt">C</span> values of the low temperature fractions were comparable to algal ∆<span class="hlt">14</span><span class="hlt">C</span>, while the high temperature fractions were <span class="hlt">14</span><span class="hlt">C</span>-depleted (older than bulk sediment). The ∆<span class="hlt">14</span><span class="hlt">C</span> end-member model indicated that ~64% of carbon in surface sediment was derived from detrital terrestrial carbon. The same proportion of detrital/labile carbon was found in surface sediment of Upper Lough Erne in 2014, despite the differences in lake type and collection date. The use of ∆<span class="hlt">14</span><span class="hlt">C</span> in conjunction with</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1987NIMPB..29..355N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1987NIMPB..29..355N"><span id="translatedtitle">Applications of environmental <span class="hlt">14</span><span class="hlt">C</span> measured by AMS as a carbon tracer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nakamura, Toshio; Nakai, Nobuyuki; Ohishi, Shoji</p> <p>1987-11-01</p> <p>AMS techniques have been applied to measure <span class="hlt">14</span><span class="hlt">C</span> concentrations, or Δ <span class="hlt">14</span><span class="hlt">C</span> values, of annual tree rings (1945-1983) of a Kiso hinoki tree grown in Gifu prefecture, and of acid-insoluble carbonaceous compounds extracted from cored sediments (surface to 30 cm deep) of Lake Biwa in Shiga prefecture. An increase in Δ <span class="hlt">14</span><span class="hlt">C</span> values was found for both tree rings and cored sediments, resulting from <span class="hlt">14</span><span class="hlt">C</span> artificially produced by nuclear weapon tests. Activities of 210Pb and 214Pb were measured to estimate the sedimentation rate of the Lake Biwa sediments and to provide a temporal control. A primitive model of carbon exchange between the troposphere, surface ocean water, and the biosphere was applied to the annual changes in Δ <span class="hlt">14</span><span class="hlt">C</span> of the hinoki tree rings and also of coral rings from Florida, USA. The times required to transfer bomb-carbon from the troposphere to surface sea water and to the biosphere were estimated to be about 11 and 23 years, respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19157836','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19157836"><span id="translatedtitle">Abundance of (<span class="hlt">14</span>)<span class="hlt">C</span> in biomass fractions of wastes and solid recovered fuels.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fellner, Johann; Rechberger, Helmut</p> <p>2009-05-01</p> <p>In recent years thermal utilization of mixed wastes and solid recovered fuels has become of increasing importance in European waste management. Since wastes or solid recovered fuels are generally composed of fossil and biogenic materials, only part of the CO(2) emissions is accounted for in greenhouse gas inventories or emission trading schemes. A promising approach for determining this fraction is the so-called radiocarbon method. It is based on different ratios of the carbon isotopes (<span class="hlt">14</span>)<span class="hlt">C</span> and (12)C in fossil and biogenic fuels. Fossil fuels have zero radiocarbon, whereas biogenic materials are enriched in (<span class="hlt">14</span>)<span class="hlt">C</span> and reflect the (14)CO(2) abundance of the ambient atmosphere. Due to nuclear weapons tests in the past century, the radiocarbon content in the atmosphere has not been constant, which has resulted in a varying (<span class="hlt">14</span>)<span class="hlt">C</span> content of biogenic matter, depending on the period of growth. In the present paper (<span class="hlt">14</span>)<span class="hlt">C</span> contents of different biogenic waste fractions (e.g., kitchen waste, paper, wood), as well as mixtures of different wastes (household, bulky waste, and commercial waste), and solid recovered fuels are determined. The calculated (<span class="hlt">14</span>)<span class="hlt">C</span> content of the materials investigated ranges between 98 and 135pMC.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5642978','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5642978"><span id="translatedtitle">Intestinal absorption and tissue distribution of ( sup <span class="hlt">14</span> <span class="hlt">C</span>)pyrroloquinoline quinone in mice</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Smidt, C.R.; Unkefer, C.J.; Houck, D.R.; Rucker, R.B. )</p> <p>1991-05-01</p> <p>Pyrroloquinoline quinone (PQQ) functions as a cofactor for prokaryotic oxidoreductases, such as methanol dehydrogenase and membrane-bound glucose dehydrogenase. In animals fed chemically defined diets, PQQ improves reproductive outcome and neonatal growth. Consequently, the present study was undertaken to determine the extent to which PQQ is absorbed by the intestine, its tissue distribution, and route of excretion. About 28 micrograms of PQQ (0.42 microCi/mumol), labeled with {sup <span class="hlt">14</span>}<span class="hlt">C</span> derived from L-tyrosine, was administered orally to Swiss-Webster mice (18-20 g) to estimate absorption. PQQ was readily absorbed (62%, range 19-89%) in the lower intestine, and was excreted by the kidneys (81% of the absorbed dose) within 24 hr. The only tissues that retained significant amounts of ({sup <span class="hlt">14</span>}<span class="hlt">C</span>)PQQ at 24 hr were skin and kidney. For kidney, it was assumed that retention of ({sup <span class="hlt">14</span>}<span class="hlt">C</span>)PQQ represented primarily PQQ destined for excretion. For skin, the concentration of ({sup <span class="hlt">14</span>}<span class="hlt">C</span>)PQQ increased from 0.3% of the absorbed dose at 6 hr to 1.3% at 24 hr. Furthermore, most of the ({sup <span class="hlt">14</span>}<span class="hlt">C</span>)PQQ in blood (greater than 95%) was associated with the blood cell fraction, rather than plasma.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/19157836','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/19157836"><span id="translatedtitle">Abundance of (<span class="hlt">14</span>)<span class="hlt">C</span> in biomass fractions of wastes and solid recovered fuels.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fellner, Johann; Rechberger, Helmut</p> <p>2009-05-01</p> <p>In recent years thermal utilization of mixed wastes and solid recovered fuels has become of increasing importance in European waste management. Since wastes or solid recovered fuels are generally composed of fossil and biogenic materials, only part of the CO(2) emissions is accounted for in greenhouse gas inventories or emission trading schemes. A promising approach for determining this fraction is the so-called radiocarbon method. It is based on different ratios of the carbon isotopes (<span class="hlt">14</span>)<span class="hlt">C</span> and (12)C in fossil and biogenic fuels. Fossil fuels have zero radiocarbon, whereas biogenic materials are enriched in (<span class="hlt">14</span>)<span class="hlt">C</span> and reflect the (14)CO(2) abundance of the ambient atmosphere. Due to nuclear weapons tests in the past century, the radiocarbon content in the atmosphere has not been constant, which has resulted in a varying (<span class="hlt">14</span>)<span class="hlt">C</span> content of biogenic matter, depending on the period of growth. In the present paper (<span class="hlt">14</span>)<span class="hlt">C</span> contents of different biogenic waste fractions (e.g., kitchen waste, paper, wood), as well as mixtures of different wastes (household, bulky waste, and commercial waste), and solid recovered fuels are determined. The calculated (<span class="hlt">14</span>)<span class="hlt">C</span> content of the materials investigated ranges between 98 and 135pMC. PMID:19157836</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4187008','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4187008"><span id="translatedtitle">Influence of increasing combustion temperature on the AMS <span class="hlt">14</span><span class="hlt">C</span> dating of modern crop phytoliths</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Yin, Jinhui; Yang, Xue; Zheng, Yonggang</p> <p>2014-01-01</p> <p>Several attempts have been made to directly date phytoliths, but most <span class="hlt">14</span><span class="hlt">C</span> results are not consistent with other independent chronologies. Due to the limited dataset, there is not a clear explanation for these discrepancies. Herein, we report the <span class="hlt">14</span><span class="hlt">C</span> ages of phytolith-occluded carbon (PhytOC) from contemporary rice and millet crops that were combusted at different temperatures to investigate the relationship between the combustion temperature and resulting <span class="hlt">14</span><span class="hlt">C</span> age. Our results show that the <span class="hlt">14</span><span class="hlt">C</span> age of PhytOC increases directly with combustion temperature (up to 1100°C) and results in age overestimations of hundreds of years. Considerably older ages are observed at higher temperatures, suggesting that it may be possible to distinguish between two fractions of organic carbon in phytoliths: labile and recalcitrant carbon. These findings challenge the assumption that PhytOC is homogeneous, an assumption made by those who have previously attempted to directly date phytoliths using <span class="hlt">14</span><span class="hlt">C</span>. PMID:25288281</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6610884','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6610884"><span id="translatedtitle">In vitro synthesis and purification of UDP-( sup <span class="hlt">14</span> <span class="hlt">C</span>) galacturonate</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mitcham, E.J. ); Gross, K.C. ); Wasserman, B.P. )</p> <p>1989-04-01</p> <p>Pectins comprise a major component of the cell wall and much research has focused on degradation of pectins during ripening and senescence. However, little research has been conducted on pectin synthesis, partly due to a lack of commercial availability of UDP-({sup <span class="hlt">14</span>}<span class="hlt">C</span>)galacturonic acid for use as a substrate in assaying galacturonan synthase. We report on the modification and integration of several procedures to synthesize UDP-({sup <span class="hlt">14</span>}<span class="hlt">C</span>) galacturonic acid from commercially available UDP-({sup <span class="hlt">14</span>}<span class="hlt">C</span>)glucuronic acid. A microsomal pellet containing UDP-D-glucuronate-4-epimerase was extracted from 5-day-old mung bean hypocotyls (Phaseolus aureus) and radish roots (Raphanus sativus L.) by ultracentrifugation at 30,000 rpm for 50 min. The UDP-({sup <span class="hlt">14</span>}<span class="hlt">C</span>)galacturonic acid produced was separated from remaining UDP-({sup <span class="hlt">14</span>}<span class="hlt">C</span>)glucuronic acid and other products by electrophoresis in pyridine:acetate:H{sub 2}O on silica gel. Spots were detected by autoradiography, eluted with 80% ethanol, and purified using anion exchange chromatography.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26369226','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26369226"><span id="translatedtitle">Bioavailability of the Nano-Unit <span class="hlt">14</span><span class="hlt">C</span>-Agrochemicals Under Various Water Potential.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jung, S C; Kim, H G; Kuk, Y I; Ahn, H G; Senseman, S A; Lee, D J</p> <p>2015-08-01</p> <p>The study was conducted to investigate the effects of water potential on bioavailability of the nano-unit <span class="hlt">14</span><span class="hlt">C</span>-cafenstrole, <span class="hlt">14</span><span class="hlt">C</span>-pretilachlor, <span class="hlt">14</span><span class="hlt">C</span>-benfuresate, <span class="hlt">14</span><span class="hlt">C</span>-simetryn and <span class="hlt">14</span><span class="hlt">C</span>-oxyfluorfen applied with or without dimepiperate or daimuron under various water potential conditions. The highest bioavailable concentration in soil solution (BCSS) was found at 60% soil moisture, while the lowest occurred at 50% soil moisture for soil-applied alone or in combination. All water potential conditions differed significantly from each other with variations in total bioavailable amount in soil solution (TBSS) when either dimepiperate or daimuron were added to the soil, and changes were directly proportional to variations in water potential. Across all treatments, TBSS at 80% soil moisture was three to four times greater than that at 50% soil moisture when applied alone or in combination with dimepiperate or daimuron. Cafenstrole and simetryn had distribution coefficient (Kd) values <64 ml g-1 and a TBSS ranging from 10 to 44 ng g-1 soil, regardless of water potential conditions applied alone or in combination. Pretilachlor and benfuresate had Kd values <15 ml g-1 and a TBSS range of 38 to 255 ng g-1 soil when applied with or without dimepiperate or daimuron.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21217163','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21217163"><span id="translatedtitle">Abundance of {sup <span class="hlt">14</span>}<span class="hlt">C</span> in biomass fractions of wastes and solid recovered fuels</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Fellner, Johann Rechberger, Helmut</p> <p>2009-05-15</p> <p>In recent years thermal utilization of mixed wastes and solid recovered fuels has become of increasing importance in European waste management. Since wastes or solid recovered fuels are generally composed of fossil and biogenic materials, only part of the CO{sub 2} emissions is accounted for in greenhouse gas inventories or emission trading schemes. A promising approach for determining this fraction is the so-called radiocarbon method. It is based on different ratios of the carbon isotopes {sup <span class="hlt">14</span>}<span class="hlt">C</span> and {sup 12}C in fossil and biogenic fuels. Fossil fuels have zero radiocarbon, whereas biogenic materials are enriched in {sup <span class="hlt">14</span>}<span class="hlt">C</span> and reflect the {sup 14}CO{sub 2} abundance of the ambient atmosphere. Due to nuclear weapons tests in the past century, the radiocarbon content in the atmosphere has not been constant, which has resulted in a varying {sup <span class="hlt">14</span>}<span class="hlt">C</span> content of biogenic matter, depending on the period of growth. In the present paper {sup <span class="hlt">14</span>}<span class="hlt">C</span> contents of different biogenic waste fractions (e.g., kitchen waste, paper, wood), as well as mixtures of different wastes (household, bulky waste, and commercial waste), and solid recovered fuels are determined. The calculated {sup <span class="hlt">14</span>}<span class="hlt">C</span> content of the materials investigated ranges between 98 and 135 pMC.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5178115','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5178115"><span id="translatedtitle">Fine structure in sup <span class="hlt">14</span> <span class="hlt">C</span> emission from sup 223 Ra and sup 224 Ra</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hourani, E.; Rosier, L.; Berrier-Ronsin, G.; Elayi, A.; Mueller, A.C.; Rappenecker, G.; Rotbard, G.; Renou, G.; Liebe, A.; Stab, L. ); Ravn, H.L. )</p> <p>1991-10-01</p> <p>The measurement of the energy spectrum of {sup <span class="hlt">14</span>}<span class="hlt">C</span> nuclei emitted in the spontaneous radioactivity of {sup 223}Ra and {sup 224}Ra has been carried out, using thin and intense sources (480 MBq for {sup 223}Ra and 3550 MBq for {sup 224}Ra). The sources were obtained by implanting mass-separated beams into Al and vitreous C catchers. The measurement was performed with a superconducting solenoidal spectrometer. Our discovery, previously reported, of fine structure in the energy spectrum of {sup <span class="hlt">14</span>}<span class="hlt">C</span> emission from {sup 223}Ra, which is analogous to the one known for {alpha} emission, is confirmed. Only 13% of the branching ratio in {sup <span class="hlt">14</span>}<span class="hlt">C</span> decay leads to the ground state of the residual nucleus, while 81% to the first excited state. For {sup <span class="hlt">14</span>}<span class="hlt">C</span> emission from {sup 224}Ra, a lower limit of 2 for the hindrance factor has been measured for the transition to the first excited state in the residual nucleus. Also, a precise identification in {ital Z} with an {ital E}{times}{Delta}{ital E} telescope has been performed for the radiation from the {sup 223}Ra source. Our measurements of fine structure in {sup <span class="hlt">14</span>}<span class="hlt">C</span> emissions open this field to nuclear structure studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25908409','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25908409"><span id="translatedtitle">Modulation of (<span class="hlt">14</span>) <span class="hlt">C</span>-labeled glucose metabolism by zinc during aluminium induced neurodegeneration.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Singla, Neha; Dhawan, D K</p> <p>2015-09-01</p> <p>Aluminium (Al) is one of the most prominent metals in the environment and is responsible for causing several neurological disorders, including Alzheimer's disease. On the other hand, zinc (Zn) is an essential micronutrient that is involved in regulating brain development and function. The present study investigates the protective potential of Zn in the uptake of (<span class="hlt">14</span>) <span class="hlt">C</span>-labeled amino acids and glucose and their turnover in rat brain slices during Al intoxication. Male Sprague Dawley rats (140-160 g) were divided into four different groups: normal control, Al treated (100 mg/kg body weight/day via oral gavage), Zn treated (227 mg/liter in drinking water), and Al + Zn treated. Radiorespirometric assay revealed an increase in glucose turnover after Al exposure that was attenuated after Zn treatment. Furthermore, the uptake of (<span class="hlt">14</span>) <span class="hlt">C</span>-labeled glucose was increased after Al treatment but was appreciably decreased upon Zn supplementation. In addition, the uptakes of (<span class="hlt">14</span>) <span class="hlt">C</span>-lysine, (<span class="hlt">14</span>) <span class="hlt">C</span>-leucine, and (<span class="hlt">14</span>) <span class="hlt">C</span>-aspartic acid were also found to be elevated following Al exposure but were decreased after Zn treatment. Al treatment also caused alterations in the neurohistoarchitecture of the brain, which were improved after Zn coadministration. Therefore, the present study suggests that Zn provides protection against Al-induced neurotoxicity by regulating glucose and amino acid uptake in rats, indicating that Zn could be a potential candidate for the treatment of various neurodegenerative disorders.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001AGUFMPP32C..11M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AGUFMPP32C..11M"><span id="translatedtitle">An Inverse Method to Infer the Global Ocean Paleoventilation from the Atmospheric <span class="hlt">14</span><span class="hlt">C</span> Record</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marchal, O.; Hughen, K. A.; Muscheler, R.</p> <p>2001-12-01</p> <p>We present an inverse method to infer a record of global ocean ventilation (GOV) from records of atmospheric <span class="hlt">14</span><span class="hlt">C</span> activity (Δ <span class="hlt">14</span><span class="hlt">C</span>) and production. The method is based on the assimilation of activity and production data in a box model of the <span class="hlt">14</span><span class="hlt">C</span> cycle in the ocean-atmosphere-land biosphere system using the variational (adjoint) technique. It includes three components: (1) the model code that yields the value of the cost function (a measure of the misfit between observed and modelled Δ <span class="hlt">14</span><span class="hlt">C</span>); (2) the adjoint code that yields the partial derivatives of the cost function with respect to the parameters describing the temporal evolution of the GOV; and (3) an optimization procedure that yields the parameter values minimizing the cost function. Lagrange multipliers are introduced to simplify the calculation of the partial derivatives of the cost function and to construct the adjoint code directly from the model code. First we describe the method, outlining the formal similarities with the calculus of variation in analytical mechanics. Second we verify the method through the capability to recover a variety of GOV evolutions from the assimilation of artificial data ("twin experiments"). Third we apply the method to the Younger Dryas, using recent high-resolution records of Δ <span class="hlt">14</span><span class="hlt">C</span> from the Cariaco basin and of 10Be flux from Greenland ice cores. Our results give new insight into the role of the deep ocean circulation during this dramatic and rapid climate change in the circum North Atlantic area.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.9514J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.9514J"><span id="translatedtitle">Release of aged <span class="hlt">14</span><span class="hlt">C</span>-atrazine residues from soil facilitated by dry-wet cycles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jablonowski, N. D.; Yu, K.; Koeppchen, S.; Burauel, P.</p> <p>2012-04-01</p> <p>Intermittent dry-wet cycles may have an important effect on soil structure and aged pesticide residues release (1). A laboratory study was conducted to assess the maximum potential of water extractable aged atrazine residues influenced by soil drying and wetting. The used soil was obtained from an outdoor lysimeter (gleyic cambisol; Corg: 1.45%), containing environmentally aged (22 years) <span class="hlt">14</span><span class="hlt">C</span>-atrazine residues. For the experiment, soil from 0-10 cm depth was used since most residual <span class="hlt">14</span><span class="hlt">C</span> activity was previously found in this layer (2,3). Triplicate soil samples with a residual water content of approx. 8% were either dried (45° C) prior water addition or directly mixed with distilled water (soil+water: 1+2, w:w). The samples were shaken (150 rmp, 60 min, at 21° C), centrifuged (approx. 2000 g), and the supernatants were filtered. Water-extracted residual <span class="hlt">14</span><span class="hlt">C</span> activity was detected via liquid scintillation counter. The total water-extracted <span class="hlt">14</span><span class="hlt">C</span> activity (the amount of residual <span class="hlt">14</span><span class="hlt">C</span> activity in a sample equals 100%) was significantly higher (p</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NIMPB.361...20F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NIMPB.361...20F"><span id="translatedtitle">Progress report on a novel in situ<span class="hlt">14</span><span class="hlt">C</span> extraction scheme at the University of Cologne</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fülöp, R.-H.; Wacker, L.; Dunai, T. J.</p> <p>2015-10-01</p> <p>We present initial results of in situ<span class="hlt">14</span><span class="hlt">C</span> system blank and calibration sample measurements obtained using the in situ<span class="hlt">14</span><span class="hlt">C</span> extraction scheme developed at the University of Cologne. The <span class="hlt">14</span><span class="hlt">C</span> extraction scheme specifically exploits the phase transformation of quartz to cristobalite in order to quantitatively extract the carbon as CO2 and follows a scheme that is different to that of existing extraction systems. Features are offline furnace extraction, single pass catalytic oxidation using mixed copper (I,II) oxide as catalyst, the use of UHV-compatible components and of vacuum annealed copper tubing. The design allows a relatively rapid sample throughput - two samples per day as opposed to the current 2 days per sample that can be done on other lines - and can accommodate samples ranging between 0.5 and 4 g of clean quartz. Following extraction and cleaning, the CO2 gas is measured using the gas ion source of the MICADAS AMS facility at ETH Zurich. The extraction system yields low systems blanks (10 +16/-10 × 103 atoms <span class="hlt">14</span><span class="hlt">C</span>, ±1 σ) and the initial results indicate that further improvements are achievable. Measurements of the CRONUS-A standard sample show a good reproducibility and results are consistent with published values. We also present the first in situ<span class="hlt">14</span><span class="hlt">C</span> results for the CRONUS-R standard material.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10234473','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10234473"><span id="translatedtitle">Cutaneous uptake of <span class="hlt">14</span><span class="hlt">C</span>-HD vapor by the hairless guinea pig.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Logan, T P; Millard, C B; Shutz, M; Schulz, S M; Lee, R B; Bongiovanni, R</p> <p>1999-05-01</p> <p>The hairless guinea pig (HGP) is used by our laboratory to model the human cutaneous response to sulfur mustard (HD), bis(2-chloroethylsulfide), exposure. We determined the HD content in the skin of HGP after a 7-min exposure to vapors saturated with a mixture of HD and <span class="hlt">14</span><span class="hlt">C</span>-HD. Concentration/time (CT) values in the range of 2 micrograms/cm2/min were determined by counting skin <span class="hlt">14</span><span class="hlt">C</span> disintegrations per min (dpm) in animals euthanized immediately after exposure. These values are similar to human penetration rates obtained by other investigators. A rate curve monitoring the reduction in skin <span class="hlt">14</span><span class="hlt">C</span> dpm was developed for animals euthanized between 0 and 24 hr post- exposure. This curve showed the greatest change after 1 hr. The epidermal (62%) to dermal (38%) ratio of <span class="hlt">14</span><span class="hlt">C</span> at 24 hr was measured for two animals. We saw no site preference for HD penetration among the 8 sites used. The <span class="hlt">14</span><span class="hlt">C</span> content of template adhesive tape was determined to follow HD distribution. These results contribute to a better understanding of the cutaneous response to HD in the HGP model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5627750','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5627750"><span id="translatedtitle">Uptake and metabolism of (<span class="hlt">14</span><span class="hlt">C</span>)-aspartate by developing kernels of maize (Zea mays L. )</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Muhitch, M.J. )</p> <p>1990-05-01</p> <p>Pulse-chase experiments were performed to determine the metabolic fate of (<span class="hlt">14</span><span class="hlt">C</span>)-aspartate in the pedicel region and subsequent uptake into the endosperm. Kernels were removed from the cob, leaving the pedicel attached but removing glumes, palea, and lemma. The basal tips were incubated in (<span class="hlt">14</span><span class="hlt">C</span>)-aspartate for 0.5 h, followed by a 2 h chase period with unlabeled aspartate. In contrast to a previous study in which 70% of the <span class="hlt">14</span><span class="hlt">C</span> from aspartate was recovered in the organic acid fraction (Lyznik, et al., Phytochemistry 24: 425, 1985), only 20 to 25% of the radioactivity found in the 2 h chase period. While a small amount of the <span class="hlt">14</span><span class="hlt">C</span> transiently appeared in alanine at the beginning of the chase period, the most heavily labeled non-fed amino acid was glutamine, which accounted for 21% of the radioactivity within the pedicel amino acid fraction by 0.5 h into the chase period. There was no evidence for asparagine synthesis within the pedicel region of the kernel. <span class="hlt">14</span><span class="hlt">C</span> recovered from the endosperm in the form of amino acids were aspartate (60%), glutamine (20%), glutamate (15%), and alanine (5%). These results suggest that some of the maternally supplied amino acids undergo metabolic conversion to other amino acids before being taken up by the endosperm.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6240169','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6240169"><span id="translatedtitle">Liquid scintillation counting of /sup <span class="hlt">14</span>/<span class="hlt">C</span> for differentiation of synthetic ethanol from ethanol of fermentation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Martin, G.E.; Noakes, J.E.; Alfonso, F.C.; Figert, D.M.</p> <p>1981-09-01</p> <p>Samples containing ethanol are fractionated on a column so that the resultant ethanol content is > 93%. Determination of /sup <span class="hlt">14</span>/<span class="hlt">C</span> by liquid scintillation counting on the ethanol fraction differentiates ethanol produced by fermentation from synthetic ethanol produced from fossil fuel sources. Twenty-seven samples were fractionated and analyzed for the /sup <span class="hlt">14</span>/<span class="hlt">C</span> isotope. Six samples were synthetic ethanol derived from ethylene gas (direct and indirect process), and yielded a mean value for /sup <span class="hlt">14</span>/<span class="hlt">C</span> isotope of 0.167 dpm/g carbon with a standard deviation (SD) of 0.066 dpm/g carbon (disintegrations per minute per gram of carbon). The remaining samples were ethanol derived from the fermentation of natural materials, such as corn, pear, sugar cane, grape, cherry, and blackberry, and yielded a mean value for /sup <span class="hlt">14</span>/<span class="hlt">C</span> isotope of 16.11 dpm/g carbon with an SD of 1.27. The /sup <span class="hlt">14</span>/<span class="hlt">C</span> values for specific mixtures of a synthetic and a natural ethanol compare favorably with the analytical values obtained by this procedure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMPP33B1687S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMPP33B1687S"><span id="translatedtitle">No evidence for a deglacial intermediate water Δ<span class="hlt">14</span><span class="hlt">C</span> anomaly in the SW Atlantic</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sortor, R. N.; Lund, D. C.</p> <p>2010-12-01</p> <p>Reconstructions of Δ<span class="hlt">14</span><span class="hlt">C</span> from the eastern tropical Pacific show that severe depletions in <span class="hlt">14</span><span class="hlt">C</span> occurred at intermediate depths during the last deglaciation (Marchitto et al. 2007; Stott et al. 2009). Marchitto et al. (2007) suggested that old radiocarbon from an isolated abyssal reservoir was injected via the Southern Ocean, and that this anomaly was then carried by Antarctic Intermediate Water (AAIW) to the tropical Pacific. However, a core from the southeastern Pacific Ocean near Chile, which is in the direct path of modern-day AAIW, does not exhibit the excursion and therefore casts doubts upon the AAIW mechanism (De Pol-Holz et al. 2010). Here we evaluate whether or not a deglacial <span class="hlt">14</span><span class="hlt">C</span> anomaly similar to that in the eastern tropical Pacific occurred at intermediate depths in the South Atlantic. We reconstructed Δ<span class="hlt">14</span><span class="hlt">C</span> using planktonic and benthic foraminifera from core KNR159-5-36GGC on the Brazil Margin (27○31’S and 46○28’W, 1268 m depth). In the modern ocean, the hydrography near this core site is heavily influenced by AAIW (Oppo & Horowitz, 2000). Benthic Δ<span class="hlt">14</span><span class="hlt">C</span> values were determined using raw benthic <span class="hlt">14</span><span class="hlt">C</span> ages and calendar-calibrated planktonic ages. The deglacial benthic Δ<span class="hlt">14</span><span class="hlt">C</span> trend at this site is similar to the atmospheric Δ<span class="hlt">14</span><span class="hlt">C</span> trend, and is consistent with U/Th-dated corals from intermediate depths on the Brazil Margin (Mangini et al. 2010). The amplitude and timing of Δ<span class="hlt">14</span><span class="hlt">C</span> changes in the foraminiferal and coral records are especially congruous during the Mystery Interval. We find no evidence in the southwestern Atlantic of a ~300‰ decrease in intermediate water Δ<span class="hlt">14</span><span class="hlt">C</span> beginning at 18 kyr BP. Changes in reservoir age of ~1000 years are required to create a Baja-like Δ<span class="hlt">14</span><span class="hlt">C</span> anomaly off Brazil, an implausible increase for a subtropical gyre location. Furthermore, the resulting sedimentation rates would be up to ~145 cm/kyr during the deglaciation, an order of magnitude higher than the average sedimentation rate for 36GGC. When our results are</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/14716006','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14716006"><span id="translatedtitle"><span class="hlt">14</span><span class="hlt">C</span> activity and global carbon cycle changes over the past 50,000 years.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hughen, K; Lehman, S; Southon, J; Overpeck, J; Marchal, O; Herring, C; Turnbull, J</p> <p>2004-01-01</p> <p>A series of <span class="hlt">14</span><span class="hlt">C</span> measurements in Ocean Drilling Program cores from the tropical Cariaco Basin, which have been correlated to the annual-layer counted chronology for the Greenland Ice Sheet Project 2 (GISP2) ice core, provides a high-resolution calibration of the radiocarbon time scale back to 50,000 years before the present. Independent radiometric dating of events correlated to GISP2 suggests that the calibration is accurate. Reconstructed <span class="hlt">14</span><span class="hlt">C</span> activities varied substantially during the last glacial period, including sharp peaks synchronous with the Laschamp and Mono Lake geomagnetic field intensity minimal and cosmogenic nuclide peaks in ice cores and marine sediments. Simulations with a geochemical box model suggest that much of the variability can be explained by geomagnetically modulated changes in <span class="hlt">14</span><span class="hlt">C</span> production rate together with plausible changes in deep-ocean ventilation and the global carbon cycle during glaciation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/15016864','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/15016864"><span id="translatedtitle">Comparison of Varve and <span class="hlt">14</span><span class="hlt">C</span> Chronologies from Steel Lake, Minnesota, USA</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tian, J; Brown, T A; Hu, F S</p> <p>2004-12-29</p> <p>Annually laminated sediments (varves) offer an effective means of acquiring high-quality paleoenvironmental records. However, the strength of a varve chronology can be compromised by a number of factors, such as missing varves, ambiguous laminations, and human counting error. We assess the quality of a varve chronology for the last three millennia from Steel Lake, Minnesota, through comparisons with nine AMS {sup <span class="hlt">14</span>}<span class="hlt">C</span> dates on terrestrial plant macrofossils from the same core. These comparisons revealed an overall 8.4% discrepancy, primarily because of missing/uncountable varves within two stratigraphic intervals characterized by low carbonate concentrations and obscure laminations. Application of appropriate correction factors to these two intervals results in excellent agreement between the varve and {sup <span class="hlt">14</span>}<span class="hlt">C</span> chronologies. These results, together with other varve studies, demonstrate that an independent age-determination method, such as {sup <span class="hlt">14</span>}<span class="hlt">C</span> dating, is usually necessary to verify, and potentially correct, varve chronologies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1989ChJOL...7...10X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1989ChJOL...7...10X"><span id="translatedtitle">Uptake and transfer of<span class="hlt">14</span><span class="hlt">C</span>-simetryne through the laboratory freshwater food chain</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xu, Ying; Lay, J. P.; Zhang, Yongyuan</p> <p>1989-03-01</p> <p>This paper deals with the bioconcentration of<span class="hlt">14</span><span class="hlt">C</span>-simetryne from water by aquatic test organisms: green algae— Monoraphidium minutum, rotifers— Brachionus rubens, daphnids— Daphnia magna, and fish— Brachydanio rerio. The chemical was bioconcentrated rapidly in all test species during the first 48 hours of experiment. The BCF values (bioconcentration factor) from all uptake studies show that simetryne has higher accumulation in algae than in rotifers, daphnids and zebra fish. The logarithm of the n-octanol/water partition coefficient of simetryne measured as 2.06±0.05 was correlated with the BCFs in the organisms as based on the lipid contents. <span class="hlt">14</span><span class="hlt">C</span>-simetryne uptake via the food-chain amounted to only 22% to 42% of the bioconcentration from water. Clearance of<span class="hlt">14</span><span class="hlt">C</span>-derived residues from fish was rapid with a half-life of 2.1 days.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26546229','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26546229"><span id="translatedtitle">Mobility Studies of (<span class="hlt">14</span>)<span class="hlt">C</span>-Chlorpyrifos in Malaysian Oil Palm Soils.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Halimah, Muhamad; Ismail, B Sahid; Nashriyah, Mat; Maznah, Zainol</p> <p>2016-01-01</p> <p>The mobility of (<span class="hlt">14</span>)<span class="hlt">C</span>-chlorpyrifos using soil TLC was investigated in this study. It was found that chlorpyrifos was not mobile in clay, clay loam and peat soil. The mobility of (<span class="hlt">14</span>)<span class="hlt">C</span>-chlorpyrifos and non-labelled chlorpyrifos was also tested with silica gel TLC using three types of developing solvent hexane (100%), hexane:ethyl acetate (95:5, v/v); and hexane:ethyl acetate (98:2, v/v). The study showed that both the (<span class="hlt">14</span>)<span class="hlt">C</span>-labelled and non-labelled chlorpyrifos have the same Retardation Factor (Rf) for different developing solvent systems. From the soil column study on mobility of chlorpyrifos, it was observed that no chlorpyrifos residue was found below 5 cm depth in three types of soil at simulation rainfall of 20, 50 and 100 mm. Therefore, the soil column and TLC studies have shown similar findings in the mobility of chlorpyrifos.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26546229','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26546229"><span id="translatedtitle">Mobility Studies of (<span class="hlt">14</span>)<span class="hlt">C</span>-Chlorpyrifos in Malaysian Oil Palm Soils.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Halimah, Muhamad; Ismail, B Sahid; Nashriyah, Mat; Maznah, Zainol</p> <p>2016-01-01</p> <p>The mobility of (<span class="hlt">14</span>)<span class="hlt">C</span>-chlorpyrifos using soil TLC was investigated in this study. It was found that chlorpyrifos was not mobile in clay, clay loam and peat soil. The mobility of (<span class="hlt">14</span>)<span class="hlt">C</span>-chlorpyrifos and non-labelled chlorpyrifos was also tested with silica gel TLC using three types of developing solvent hexane (100%), hexane:ethyl acetate (95:5, v/v); and hexane:ethyl acetate (98:2, v/v). The study showed that both the (<span class="hlt">14</span>)<span class="hlt">C</span>-labelled and non-labelled chlorpyrifos have the same Retardation Factor (Rf) for different developing solvent systems. From the soil column study on mobility of chlorpyrifos, it was observed that no chlorpyrifos residue was found below 5 cm depth in three types of soil at simulation rainfall of 20, 50 and 100 mm. Therefore, the soil column and TLC studies have shown similar findings in the mobility of chlorpyrifos. PMID:26546229</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/19002633','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/19002633"><span id="translatedtitle">Distribution of <span class="hlt">14</span><span class="hlt">C</span>-TNT and derivatives in different biochemical compartments of Phaseolus vulgaris.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sens, C; Scheidemann, P; Klunk, A; Werner, D</p> <p>1998-01-01</p> <p>(<span class="hlt">14</span>)<span class="hlt">C</span>-TNT was used to quantify the uptake rate and metabolic turnover of TNT in Phaseolus vulgaris. Seventeen plants were analysed by a special cell fractionation method with polar and nonpolar solvents and enzymes. We obtained three cytoplasmic fractions and five cell wall derived fractions. The recovery rate was 72% as measured by liquid scintillation counting. (<span class="hlt">14</span>)<span class="hlt">C</span> partitioned almost in equal amounts with approximately 50% in the cytoplasm and in the cell wall. The majority of the TNT-metabolites are present in the cytoplasm as was shown by GC/ECD and thin layer chromatography. The(<span class="hlt">14</span>)<span class="hlt">C</span> in the cell wall is bound probably resulting in long-term immobilisation of these metabolites. We conclude that plants may also be a model for nitroaromatic turnover and immobilisation in soil components. PMID:19002633</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70021309','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70021309"><span id="translatedtitle">A climatic record from <span class="hlt">14</span><span class="hlt">C</span>-dated wood fragments from southwestern Colorado</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Epstein, S.; Xu, X.; Carrara, P.</p> <p>1999-01-01</p> <p>Deuterium concentrations in trees are related to the climatic temperature at which the trees grew. Deuterium analyses were made on all available (39) <span class="hlt">14</span><span class="hlt">C</span>-dated (all <span class="hlt">14</span><span class="hlt">C</span> dates cited are uncorrected) wood fragments collected from Lake Emma sediments. The <span class="hlt">14</span><span class="hlt">C</span> dates range from 9600 to 5400 'B.P.'. Tree line was above Lake Emma at 9600 'B.P.', was at Lake Emma at about 5000 'B.P.', and is 80 m below Lake Emma at the present time. The isotopic records at the various intervals of time coincide very well with this history. The range of ??D values is maximum at 9600 'B.P.' and is minimum at about 5400 'B.P.'. These data allow us to estimate the temperature range for the area between tree line and Lake Emma between these times. These results confirm previously observed cooling trends from several sources in the Western Hemisphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25590997','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25590997"><span id="translatedtitle">An analytical method for <span class="hlt">14</span><span class="hlt">C</span> in environmental water based on a wet-oxidation process.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Huang, Yan-Jun; Guo, Gui-Yin; Wu, Lian-Sheng; Zhang, Bing; Chen, Chao-Feng; Zhang, Hai-Ying; Qin, Hong-Juan; Shang-Guan, Zhi-Hong</p> <p>2015-04-01</p> <p>An analytical method for (<span class="hlt">14</span>)<span class="hlt">C</span> in environmental water based on a wet-oxidation process was developed. The method can be used to determine the activity concentrations of organic and inorganic (<span class="hlt">14</span>)<span class="hlt">C</span> in environmental water, or total (<span class="hlt">14</span>)<span class="hlt">C</span>, including in drinking water, surface water, rainwater and seawater. The wet-oxidation of the organic component allows the conversion of organic carbon to an inorganic form, and the extraction of the inorganic (<span class="hlt">14</span>)<span class="hlt">C</span> can be achieved by acidification and nitrogen purging. Environmental water with a volume of 20 L can be used for the wet-oxidation and extraction, and a detection limit of about 0.02 Bq/g(C) can be achieved for water with carbon content above 15 mg(C)/L, obviously lower than the natural level of (<span class="hlt">14</span>)<span class="hlt">C</span> in the environment. The collected carbon is sufficient for measurement with a low level liquid scintillation counter (LSC) for typical samples. Extraction or recovery experiments for inorganic carbon and organic carbon from typical materials, including analytical reagents of organic benzoquinone, sucrose, glutamic acid, nicotinic acid, humic acid, ethane diol, et cetera., were conducted with excellent results based on measurement on a total organic carbon analyzer and LSC. The recovery rate for inorganic carbon ranged tween 98.7%-99.0% with a mean of 98.9(± 0.1)%, for organic carbon recovery ranged between 93.8% and 100.0% with a mean of 97.1(± 2.6)%. Verification and an uncertainty budget of the method are also presented for a representative environmental water. The method is appropriate for (<span class="hlt">14</span>)<span class="hlt">C</span> analysis in environmental water, and can be applied also to the analysis of liquid effluent from nuclear facilities. PMID:25590997</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6617806','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6617806"><span id="translatedtitle">Effect of foliar treatments on distribution of /sup <span class="hlt">14</span>/<span class="hlt">C</span>-glyphosate in Convolvulus arvensis L</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lauridson, T.C.</p> <p>1986-01-01</p> <p>Field bindweed is a perennial weed which produces shoots from buds on its roots. Herbicides, such as glyphosate (N-(phosphonomethyl)glycine) used for control of field bindweed usually do not kill all shoot buds on the roots, thus field bindweed often reinfests areas within 3 to 6 weeks of treatment. This dissertation deals with the development of a technique to change glyphosate distribution in field bindweed roots and could result in less shoot regrowth after glyphosate application. In field studies eight plant growth regulators were applied in September, 3 days before 2.24 kg/ha of 2.4-D((2,4-dichlorophenoxy) acetic acid) or 1.68 kg/ha of glyphosate. Eight months later, regrowth of shoots was least where glyphosate was applied at 0.028 kg/ha as a pretreatment, followed by a standard rate of 1.68 kg/ha. In subsequent greenhouse studies, typical patterns of shoot growth and /sup <span class="hlt">14</span>/<span class="hlt">C</span>-glyphosate distribution in isolated root sections taken from 15-week-old intact plants were determined. In subsequent growth chamber studies, plants were decapitated to observe the effect of shoot apical dominance on /sup <span class="hlt">14</span>/<span class="hlt">C</span>-glyphosate translocation. After /sup <span class="hlt">14</span>/<span class="hlt">C</span>-glyphosate was applied, intact plants had about twice as much /sup <span class="hlt">14</span>/<span class="hlt">C</span> in distal root sections as in proximal or middle root sections. Decapitated plants had more /sup <span class="hlt">14</span>/<span class="hlt">C</span> in proximal and middle root sections than in distal sections, and about twice as much /sup <span class="hlt">14</span>/<span class="hlt">C</span> was translocated to roots of decapitated plants than intact plants. Eight concentrations of 2,4,-D or glyphosate from 1 to 5000 ppm were applied in logarithmic series to 6-week old plants.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25590997','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25590997"><span id="translatedtitle">An analytical method for <span class="hlt">14</span><span class="hlt">C</span> in environmental water based on a wet-oxidation process.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Huang, Yan-Jun; Guo, Gui-Yin; Wu, Lian-Sheng; Zhang, Bing; Chen, Chao-Feng; Zhang, Hai-Ying; Qin, Hong-Juan; Shang-Guan, Zhi-Hong</p> <p>2015-04-01</p> <p>An analytical method for (<span class="hlt">14</span>)<span class="hlt">C</span> in environmental water based on a wet-oxidation process was developed. The method can be used to determine the activity concentrations of organic and inorganic (<span class="hlt">14</span>)<span class="hlt">C</span> in environmental water, or total (<span class="hlt">14</span>)<span class="hlt">C</span>, including in drinking water, surface water, rainwater and seawater. The wet-oxidation of the organic component allows the conversion of organic carbon to an inorganic form, and the extraction of the inorganic (<span class="hlt">14</span>)<span class="hlt">C</span> can be achieved by acidification and nitrogen purging. Environmental water with a volume of 20 L can be used for the wet-oxidation and extraction, and a detection limit of about 0.02 Bq/g(C) can be achieved for water with carbon content above 15 mg(C)/L, obviously lower than the natural level of (<span class="hlt">14</span>)<span class="hlt">C</span> in the environment. The collected carbon is sufficient for measurement with a low level liquid scintillation counter (LSC) for typical samples. Extraction or recovery experiments for inorganic carbon and organic carbon from typical materials, including analytical reagents of organic benzoquinone, sucrose, glutamic acid, nicotinic acid, humic acid, ethane diol, et cetera., were conducted with excellent results based on measurement on a total organic carbon analyzer and LSC. The recovery rate for inorganic carbon ranged tween 98.7%-99.0% with a mean of 98.9(± 0.1)%, for organic carbon recovery ranged between 93.8% and 100.0% with a mean of 97.1(± 2.6)%. Verification and an uncertainty budget of the method are also presented for a representative environmental water. The method is appropriate for (<span class="hlt">14</span>)<span class="hlt">C</span> analysis in environmental water, and can be applied also to the analysis of liquid effluent from nuclear facilities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20021170','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20021170"><span id="translatedtitle">Application and detection of (<span class="hlt">14</span>)<span class="hlt">c</span>-hd in two mouse models.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Logan, Thomas P; Shutz, Michael; Schulz, Susan M; Railer, Roy; Ricketts, Karen M; Casillas, Robert P</p> <p>2002-01-01</p> <p>The CD1-haired mouse and the SKH-hairless mouse are two animal models that have been used to evaluate sulfur mustard (HD) exposure and protection in our laboratory. In a recent study we observed that a substance P inhibitor protected the haired mouse ear against an HD solution, but the same drug was not successful in protecting the hairless mouse against HD vapor. This experiment prompted us to compare HD exposures between these models. We determined the (<span class="hlt">14</span>)<span class="hlt">C</span> content in the skin after exposures to HD containing (<span class="hlt">14</span>)<span class="hlt">C</span>-HD. Rate curves were generated for applications of (1) HD in methylene chloride to the haired mouse ear; (2) HD in methylene chloride to the hairless mouse dorsal skin; and (3) saturated HD vapor to the hairless mouse dorsal skin for 6 min. The curves showed a reduction in (<span class="hlt">14</span>)<span class="hlt">C</span> disintegrations per min in animals euthanized 0 to 2 h postexposure. The largest percentage of decrease of (<span class="hlt">14</span>)<span class="hlt">C</span> content in skin occurred within 30 min of HD challenge for all exposures. An 8-mm skin-punch biopsy and a 14-mm annular skin section surrounding the region of the 8-mm skin punch were taken from the hairless mouse dorsal skin exposed to HD in methylene chloride. The ratio of the (<span class="hlt">14</span>)<span class="hlt">C</span> content in the 8-mm skin punch to that in the surrounding 14-mm annular skin section was 7.3, demonstrating that the HD application spreads beyond the initially biopsied site. A concentration/time value of 6.3 mug/cm(2)/min was determined by counting skin (<span class="hlt">14</span>)<span class="hlt">C</span> disintegrations per minute in animals euthanized immediately after exposure to saturated HD vapor. Determinations of the amount of HD showed that similar quantities of HD, 0.4 mg, were detected on each model. These results contribute to a better quantitative understanding of HD application in the haired and hairless mouse models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1817289P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1817289P"><span id="translatedtitle">Carbon and <span class="hlt">14</span><span class="hlt">C</span> distribution in tropical and subtropical agricultural soils</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Prastowo, Erwin; Grootes, Pieter; Nadeau, Marie</p> <p>2016-04-01</p> <p>Paddy soil management affects, through the alternating anoxic and oxic conditions it creates, the transport and stabilisation of soil organic matter (SOM). Irrigation water may percolate more organic materials - dissolved (DOM) and colloidal - into the subsoil during anoxic conditions. Yet a developed ploughpan tends to prevent C from going deeper in the subsoil and partly decouple C distribution in top and sub soil. We investigate the influence of different soil type and environment. We observed the C and <span class="hlt">14</span><span class="hlt">C</span> distribution in paddy and non-paddy soil profiles in three different soil types from four different climatic regions of tropical Indonesia, and subtropical China. Locations were Sukabumi (Andosol, ca. 850 m a.s.l), Bogor (clayey Alisol, ca. 240 m a.s.l), and Ngawi (Vertisol, ca. 70 m a.s.l) in Jawa, Indonesia, and Cixi (Alisol(sandy), ca. 4 - 6 m a.s.l) in Zhejiang Province, China. We compared rice paddies with selected neighbouring non-paddy fields and employed AMS <span class="hlt">14</span><span class="hlt">C</span> as a tool to study C dynamics from bulk, alkali soluble-humic, and insoluble humin samples, and macrofossils (plant remains, charcoal). Our data suggest that vegetation type determines the quantity and quality of biomass introduced as litter and root material in top and subsoil, and thus contributes to the soil C content and profile, which fits the <span class="hlt">14</span><span class="hlt">C</span> signal distribution, as well as 13C in Ngawi with C4 sugar cane as upland crop. <span class="hlt">14</span><span class="hlt">C</span> concentrations for the mobile humic acid fraction were generally higher than for bulk samples from the same depth, except when recent plant and root debris led to high <span class="hlt">14</span><span class="hlt">C</span> levels in near-surface samples. The difference in sampling, - averaged layer for bulk sample and 1-cm layer thickness for point sample - shows gradients in C and <span class="hlt">14</span><span class="hlt">C</span> across the layers, which could be a reason for discrepancies between the two. High <span class="hlt">14</span><span class="hlt">C</span> concentrations - in Andosol Sukabumi up to 111 pMC - exceed the atmospheric 14CO2concentration in the sampling year in 2012 (˜ 103 pMC) and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6880052','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6880052"><span id="translatedtitle">A study of placental transfer mechanisms in nonhuman primates using (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)phenylalanine</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Pueschel, S.M.; Boylan, J.M.; Jackson, B.T.; Piasecki, G.J.</p> <p>1982-02-01</p> <p>Placental transfer mechanisms were investigated in pregnant Macaca Fascicularis and Macaca mulatta during the gestational age of 120 to 130 days. These primates underwent an operative procedure that allowed continuous fetal blood sampling. The administration of (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)phenylalanine into the maternal circulation revealed a significant increase of radioactive material in the fetal circulation, indicating an active placental transport mechanism unidirectional to the fetus. When (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)phenylalanine was injected into the fetus, radioactive aromatic amino acids in the maternal circulation increased only slightly over time, resembling a simple diffusion process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5502689','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5502689"><span id="translatedtitle">In vivo survival of (<span class="hlt">14</span><span class="hlt">C</span>)sucrose-loaded porcine carrier erythrocytes</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>DeLoach, J.R.</p> <p>1983-06-01</p> <p>Porcine carrier erythrocyte survival was measured in adult pigs. (<span class="hlt">14</span><span class="hlt">C</span>)Sucrose-loaded erythrocytes had a biphasic survival curve, with as much as 50% of the cells removed from circulation in the first 24 hours. The remaining cells had a 35-day half-life. Encapsulation values were measured for porcine erythrocytes and entrapment of (<span class="hlt">14</span><span class="hlt">C</span>)sucrose was greater than 45%. Addition of inosine and glucose to the dialyzed cells and to the final wash buffer before reinjection of autologous cells did not improve their survival.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AN....336..930N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AN....336..930N"><span id="translatedtitle">Variations of <span class="hlt">14</span><span class="hlt">C</span> around AD 775 and AD 1795 - due to solar activity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Neuhäuser, R.; Neuhäuser, D. L.</p> <p>2015-12-01</p> <p>The motivation for our study is the disputed cause for the strong variation of <span class="hlt">14</span><span class="hlt">C</span> around AD 775. Our method is to compare the <span class="hlt">14</span><span class="hlt">C</span> variation around AD 775 with other periods of strong variability. Our results are: (a) We see three periods, where <span class="hlt">14</span><span class="hlt">C</span> varied over 200 yr in a special way showing a certain pattern of strong secular variation: after a Grand Minimum with strongly increasing <span class="hlt">14</span><span class="hlt">C</span>, there is a series of strong short-term drop(s), rise(s), and again drop(s) within 60 yr, ending up to 200 yr after the start of the Grand Minimum. These three periods include the strong rises around BC 671, AD 775, and AD 1795. (b) We show with several solar activity proxies (radioisotopes, sunspots, and aurorae) for the AD 770s and 1790s that such intense rapid <span class="hlt">14</span><span class="hlt">C</span> increases can be explained by strong rapid decreases in solar activity and, hence, wind, so that the decrease in solar modulation potential leads to an increase in radioisotope production. (c) The strong rises around AD 775 and 1795 are due to three effects, (i) very strong activity in the previous cycles (i.e. very low <span class="hlt">14</span><span class="hlt">C</span> level), (ii) the declining phase of a very strong Schwabe cycle, and (iii) a phase of very weak activity after the strong <span class="hlt">14</span><span class="hlt">C</span> rise - very short and/or weak cycle(s) like the suddenly starting Dalton minimum. (d) Furthermore, we can show that the strong change at AD 1795 happened after a pair of two packages of four Schwabe cycles with certain hemispheric leadership (each package consists of two Gnevyshev-Ohl pairs, respectively two Hale-Babcock pairs). We show with several additional arguments that the rise around AD 775 was not that special. We conclude that such large, short-term rises in <span class="hlt">14</span><span class="hlt">C</span> (around BC 671, AD 775, and 1795) do not need to be explained by highly unlikely solar super-flares nor other rare events, but by extra-solar cosmic rays modulated due to solar activity variations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/2648055','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/2648055"><span id="translatedtitle">A rapid phospholipase A2 bioassay using <span class="hlt">14</span><span class="hlt">C</span>-oleate-labelled E. coli bacterias.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Meyer, T; von Wichert, P; Weins, D</p> <p>1989-02-01</p> <p>Two methods of phospholipase A2 determination using <span class="hlt">14</span><span class="hlt">C</span>-labelled E. coli bacterias as substrate were compared. One method works with a filter membrane for separation of cleaved <span class="hlt">14</span><span class="hlt">C</span>-oleate from remaining phospholipids, the other uses the well-known thin-layer chromatography for lipid analysis. Some features of human serum phospholipase A2 regarding pH and Ca2+ dependency were investigated. Possible sources of errors were discussed. It was shown that either method can differentiate between normal and pathologically elevated phospholipase A2 levels, but that the filter method is superior in terms of sensitivity and workload.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/4035680','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/4035680"><span id="translatedtitle">Disposition of [<span class="hlt">14</span><span class="hlt">C</span>]methyl bromide in rats after inhalation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bond, J A; Dutcher, J S; Medinsky, M A; Henderson, R F; Birnbaum, L S</p> <p>1985-04-01</p> <p>Methyl bromide is used as a disinfectant to fumigate soil and a wide range of stored food commodities in warehouses and mills. Human exposure occurs during the manufacture and use of the chemical. The purpose of this investigation was to determine the disposition and metabolism of [<span class="hlt">14</span><span class="hlt">C</span>]methyl bromide in rats after inhalation. Male Fischer-344 rats were exposed nose only to a vapor concentration of 337 nmol [<span class="hlt">14</span><span class="hlt">C</span>]methyl bromide/liter air (9.0 ppm, 25 degrees C, 620 torr) for 6 hr. Urine, feces, expired air, and tissues were collected for up to 65 hr after exposure. Elimination of <span class="hlt">14</span><span class="hlt">C</span> as 14CO2 was the major route of excretion with about 47% (3900 nmol/rat) of the total [<span class="hlt">14</span><span class="hlt">C</span>]methyl bromide absorbed excreted by this route. CO2 excretion exhibited a biphasic elimination pattern with 85% of the 14CO2 being excreted with a half-time of 3.9 +/- 0.1 hr (means +/- SE) and 15% excreted with a half-time of 11.4 +/- 0.2 hr. Half-times for elimination of <span class="hlt">14</span><span class="hlt">C</span> in urine and feces were 9.6 +/- 0.1 and 16.1 +/- 0.1 hr, respectively. By 65 hr after exposure, about 75% of the initial radioactivity had been excreted with 25% remaining in the body. Radioactivity was widely distributed in tissues immediately following exposure with lung (250 nmol equivalents/g), adrenal (240 nmol equivalents/g), kidney (180 nmol equivalents/g), liver (130 nmol equivalents/g), and nasal turbinates (110 nmol equivalents/g) containing the highest concentrations of <span class="hlt">14</span><span class="hlt">C</span>. Radioactivity in livers immediately after exposure accounted for about 17% of the absorbed methyl bromide. Radioactivity in all other tissues examined accounted for about 10% of the absorbed methyl bromide. Elimination half-times of <span class="hlt">14</span><span class="hlt">C</span> from tissues were on the order of 1.5 to 8 hr. In all tissues examined, over 90% of the <span class="hlt">14</span><span class="hlt">C</span> in the tissues was methyl bromide metabolites. The data from this study indicate that after inhalation methyl bromide is rapidly metabolized in tissues and readily excreted.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.8491L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.8491L"><span id="translatedtitle">Modelling of dead carbon fraction in speleothems: a step towards reliable speleothem <span class="hlt">14</span><span class="hlt">C</span>-chronologies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lechleitner, Franziska A.; Jamieson, Robert A.; McIntyre, Cameron; Baldini, Lisa M.; Baldini, James U. L.; Eglinton, Timothy I.</p> <p>2015-04-01</p> <p>Over the past two decades, speleothems have become one of the most versatile and promising archives for the study of past continental climate. Very precise absolute dating is often possible using the U-Th method, resulting in paleoclimate records of exceptional resolution and accuracy. However, not all speleothems are amenable to this dating method for a variety of reasons (e.g. low U concentrations, high detrital Th etc). This has lead researchers to exclude many otherwise suitable speleothems and cave sites from further investigation. <span class="hlt">14</span><span class="hlt">C</span>-dating of speleothems has so far not been applicable, due to the 'dead carbon' problem. As drip water percolates through the karst, dissolving CaCO3, a variable amount of <span class="hlt">14</span><span class="hlt">C</span>-dead carbon is added to the solution. This results in a temporally variable and site-specific reservoir effect, ultimately undermining the development of speleothem <span class="hlt">14</span><span class="hlt">C</span> -chronologies. However, a number of recent studies have shown a clear link between karst hydrology and associated proxies (e.g., Mg/Ca and δ13C) and this 'dead carbon fraction' (DCF). We take advantage of this relationship to model DCF and its changes using Mg/Ca, δ13C and <span class="hlt">14</span><span class="hlt">C</span> data from published speleothem records. Using one record for calibration purposes, we build a transfer function for the DCF in relation to δ13C and Mg/Ca, which we then apply to other <span class="hlt">14</span><span class="hlt">C</span> records. Initial model results are promising; we are able to reconstruct general long-term average DCF within uncertainties of the calculated DCF from the U-Th chronology. Large shifts in DCF related to hydrology are also often detected. In a second step, we apply the model to a speleothem from southern Poland, which so far could not be dated, due to very low U-concentrations. To construct a <span class="hlt">14</span><span class="hlt">C</span> chronology, the stalagmite was sampled at 5 mm intervals. CaCO3 powders were graphitized and measured by Accelerator Mass Spectrometry (MICADAS) at ETH Zurich. Additional high-resolution (0.1 mm/sample) <span class="hlt">14</span><span class="hlt">C</span> measurements were performed on</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2003QSRv...22.1485B&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2003QSRv...22.1485B&link_type=ABSTRACT"><span id="translatedtitle">A numerical approach to <span class="hlt">14</span><span class="hlt">C</span> wiggle-match dating of organic deposits: best fits and confidence intervals</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Blaauw, Maarten; Heuvelink, Gerard B. M.; Mauquoy, Dmitri; van der Plicht, Johannes; van Geel, Bas</p> <p>2003-06-01</p> <p><span class="hlt">14</span><span class="hlt">C</span> wiggle-match dating (WMD) of peat deposits uses the non-linear relationship between <span class="hlt">14</span><span class="hlt">C</span> age and calendar age to match the shape of a sequence of closely spaced peat <span class="hlt">14</span><span class="hlt">C</span> dates with the <span class="hlt">14</span><span class="hlt">C</span> calibration curve. A numerical approach to WMD enables the quantitative assessment of various possible wiggle-match solutions and of calendar year confidence intervals for sequences of <span class="hlt">14</span><span class="hlt">C</span> dates. We assess the assumptions, advantages, and limitations of the method. Several case-studies show that WMD results in more precise chronologies than when individual <span class="hlt">14</span><span class="hlt">C</span> dates are calibrated. WMD is most successful during periods with major excursions in the <span class="hlt">14</span><span class="hlt">C</span> calibration curve (e.g., in one case WMD could narrow down confidence intervals from 230 to 36 yr).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7012191','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7012191"><span id="translatedtitle">Percutaneous absorption of (7. 10-/sup <span class="hlt">14</span>/<span class="hlt">C</span>)benzo(a)pyrene and (7,12-/sup <span class="hlt">14</span>/<span class="hlt">C</span>)dimethylbenz(a)anthracene in mice</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sanders, C.L.; Skinner, C.; Gelman, R.A.</p> <p>1984-04-01</p> <p>The percutaneous penetration, tissue distribution, and excretion of /sup <span class="hlt">14</span>/<span class="hlt">C</span>-labeled benzo(a)pyrene (BaP) and dimethylbenz(a)anthracene (DMBA) were studied in mice. Both BaP and DMBA rapidly penetrated the skin and were excreted more in the feces than in the urine. The proportion of BaP or DMBA absorbed was less with increasing applied dose due to apparent saturation of the uptake process. Uptake from the dorsal skin of the nose was similar to uptake from the dorsal nuchal skin. 24 references.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17..885H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17..885H"><span id="translatedtitle">Distribution of root exudates and mucilage in the rhizosphere: combining <span class="hlt">14</span><span class="hlt">C</span> imaging with neutron radiography</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Holz, Maire; Carminati, Andrea; Kuzyakov, Yakov</p> <p>2015-04-01</p> <p>Water and nutrients will be the major factors limiting food production in future. Plant roots employ various mechanisms to increase the access to limited soil resources. Low molecular weight organic substances released by roots into the rhizosphere increase nutrient availability by interactions with microorganisms, while mucilage improves water availability under low moisture conditions. Though composition and quality of these substances have intensively been investigated, studies on the spatial distribution and quantification of exudates in soil are scarce. Our aim was to quantify and visualize root exudates and mucilage distribution around growing roots using neutron radiography and <span class="hlt">14</span><span class="hlt">C</span> imaging depending on drought stress. Plants were grown in rhizotrons well suited for neutron radiography and <span class="hlt">14</span><span class="hlt">C</span> imaging. Plants were exposed to various soil water contents experiencing different levels of drought stress. The water content in the rhizosphere was imaged during several drying/wetting cycles by neutron radiography. The radiographs taken a few hours after irrigation showed a wet region around the root tips showing the allocation and distribution of mucilage. The increased water content in the rhizosphere of the young root segments was related to mucilage concentrations by parameterization described in Kroener et al. (2014). In parallel <span class="hlt">14</span><span class="hlt">C</span> imaging of root after 14CO2 labeling of shoots (Pausch and Kuzyakov 2011) showed distribution of rhizodeposits including mucilage. Three days after setting the water content, plants were labeled in 14CO2 atmosphere. Two days later <span class="hlt">14</span><span class="hlt">C</span> distribution in soil was imaged by placing a phosphor-imaging plate on the rhizobox. To quantify rhizodeposition, <span class="hlt">14</span><span class="hlt">C</span> activity on the image was related to the absolute <span class="hlt">14</span><span class="hlt">C</span> activity in the soil and root after destructive sampling. By comparing the amounts of mucilage (neutron radiography) with the amount of total root derived C (<span class="hlt">14</span><span class="hlt">C</span> imaging), we were able to differentiate between mucilage and root</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3768407','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3768407"><span id="translatedtitle">Fate of organochlorine <span class="hlt">14</span><span class="hlt">C</span>-dicofol in a lab-scale wastewater treatment</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Oliveira, Jaime L. M.; Langenbach, Tomaz; Dezotti, Márcia</p> <p>2008-01-01</p> <p>The fate of organochlorine <span class="hlt">14</span><span class="hlt">C</span>-dicofol in activated sludge process was investigated. Results showed that the major part of radioactivity remained adsorbed on biological sludge. Consequently, its final disposal deserves special attention. The small amounts of dicofol, biotransformed or not, which remained in the treated effluent could contaminate receiving bodies. PMID:24031222</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70026487','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70026487"><span id="translatedtitle">Stepped-combustion <span class="hlt">14</span><span class="hlt">C</span> dating of bomb carbon in lake sediment</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>McGeehin, J.; Burr, G.S.; Hodgins, G.; Bennett, S.J.; Robbins, J.A.; Morehead, N.; Markewich, H.</p> <p>2004-01-01</p> <p>In this study, we applied a stepped-combustion approach to dating post-bomb lake sediment from north-central Mississippi. Samples were combusted at a low temperature (400 ??C) and then at 900 ??C. The CO2 was collected separately for both combustions and analyzed. The goal of this work was to develop a methodology to improve the accuracy of <span class="hlt">14</span><span class="hlt">C</span> dating of sediment by combusting at a lower temperature and reducing the amount of reworked carbon bound to clay minerals in the sample material. The <span class="hlt">14</span><span class="hlt">C</span> fraction modern results for the low and high temperature fractions of these sediments were compared with well-defined 137Cs determinations made on sediment taken from the same cores. Comparison of "bomb curves" for <span class="hlt">14</span><span class="hlt">C</span> and 137Cs indicate that low temperature combustion of sediment improved the accuracy of <span class="hlt">14</span><span class="hlt">C</span> dating of the sediment. However, fraction modern results for the low temperature fractions were depressed compared to atmospheric values for the same time frame, possibly the result of carbon mixing and the low sedimentation rate in the lake system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22717552','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22717552"><span id="translatedtitle">Dating ivory by determination of <span class="hlt">14</span><span class="hlt">C</span>, 90Sr and 228/232Th.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Schmied, Stefanie A K; Brunnermeier, Matthias J; Schupfner, Robert; Wolfbeis, Otto S</p> <p>2012-09-10</p> <p>A method is described to determine the time of death of elephants. This is accomplished by analysis of the radionuclides <span class="hlt">14</span><span class="hlt">C</span>, 90Sr and 228/232Th in known samples of ivory, and in samples of unknown age. The reliability of this method is considerably increased by multi nuclide analysis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=243554','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=243554"><span id="translatedtitle"><span class="hlt">14</span><span class="hlt">C</span>-most-probable-number method for enumeration of active heterotrophic microorganisms in natural waters.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Lehmicke, L G; Williams, R T; Crawford, R L</p> <p>1979-01-01</p> <p>A most-probable-number method using <span class="hlt">14</span><span class="hlt">C</span>-labeled substrates is described for the enumeration of aquatic populations of heterotrophic microorganisms. Natural populations of microorganisms are inoculated into dilution replicates prepared from the natural water from which the organisms originated. The natural water is supplemented with a <span class="hlt">14</span><span class="hlt">C</span>-labeled compound added so as to approximate a true environmental concentration. 14CO2 evolved by individual replicates is trapped in NaOH and counted by liquid scintillation techniques for use in scoring replicates as positive or negative. Positives (14CO2 evolution) are easily distinguished from negatives (no 14CO2 evolution). The results from a variety of environments using the 14CO2 procedure agreed well with previously described methods, in most instances. The <span class="hlt">14</span><span class="hlt">C</span>-most-probable-number method described here reduces handling procedures over previously described most-probable-number procedures using <span class="hlt">14</span><span class="hlt">C</span>-labeled substrates. It also appears to have advantages over other enumeration methods in its attempt to approximate natural conditions more closely. PMID:120133</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/9064240','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/9064240"><span id="translatedtitle">Disposition of <span class="hlt">14</span><span class="hlt">C</span>-derived residues in tissues of pigs fed radiolabelled fumonisin B1.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Prelusky, D B; Miller, J D; Trenholm, H L</p> <p>1996-01-01</p> <p>The uptake and distribution of radioactive material-derived residues were determined in tissues of growing pigs consuming <span class="hlt">14</span><span class="hlt">C</span>-labelled fumonisin B1 (FB1) in the diet. Animals were fed 3.0 mg (3.0 microCi) <span class="hlt">14</span><span class="hlt">C</span>-FB1/kg feed from days 1-12, followed by 2.0 mg (2.0 microCi) <span class="hlt">14</span><span class="hlt">C</span>-FB1/kg feed during days 13-24, followed by a 9-day withdrawal period where pigs received clean feed only. Of the tissues analysed, residues were found to accumulate only in liver and kidney. Radioactivity was detected at the first sampling time (day 3), and continued to increase until the <span class="hlt">14</span><span class="hlt">C</span>-toxin was removed from the diet. Peak tissue levels (dpm/g tissue +/- SD, N = 2) in liver and kidney were 347 +/- 28 and 146 +/- 14, respectively, on day 24, which were equivalent to about 160 and 65 ng FB1 and/or metabolites per g tissue, respectively. Once pigs were placed on clean feed, tissue levels declined rapidly; down to approximately 35% of peak levels after 3 days, and only marginally above detection limits (approximately 25 dpm/g) after 9 days. Delayed recovery of the radioactive material consumed indicated a persistence within the body of FB1-derived residues, which could be eliminated only upon removal of the contaminated diet. PMID:9064240</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70017119','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70017119"><span id="translatedtitle">Accuracy of post-bomb 137Cs and <span class="hlt">14</span><span class="hlt">C</span> in dating fluvial deposits</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Ely, L.L.; Webb, R.H.; Enzel, Y.</p> <p>1992-01-01</p> <p>The accuracy and precision of 137Cs and <span class="hlt">14</span><span class="hlt">C</span> for dating post-1950 alluvial deposits were evaluated for deposits from known floods on two rivers in Arizona. The presence of 137Cs reliably indicates that deposition occurred after intensive above-ground nuclear testing was initiated around 1950. There was a positive correlation between the measured level of 137Cs activity and the clay content of the sediments, although 137Cs was detected even in sandy flood sediments with low clay content. 137Cs is a valuable dating tool in arid environments where organic materials for <span class="hlt">14</span><span class="hlt">C</span> or tree-ring dating are scarce and observational records are limited. The <span class="hlt">14</span><span class="hlt">C</span> activity measured in different types of fine organic detritus yielded dates within 1 to 8 yr of a 1980 flood deposit, and the accuracy was species-dependent. However, undifferentiated mixtures of fine organic materials from several post-bomb deposits of various ages repeatedly yielded dates between 1958 and 1962, and detrital charcoal yielded a date range of 1676-1939. In semiarid environments, the residence time of most types of organic debris precludes accurate annual resolution of post-bomb <span class="hlt">14</span><span class="hlt">C</span> dates. ?? 1992.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5512198','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5512198"><span id="translatedtitle">Kinetics of the uptake of sup <span class="hlt">14</span> <span class="hlt">C</span>-labeled chlorinated benzenes from soil by plants</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Topp, E.; Scheunert, I.; Korte, F. )</p> <p>1989-04-01</p> <p>({sup <span class="hlt">14</span>}<span class="hlt">C</span>)Benzene, ({sup <span class="hlt">14</span>}<span class="hlt">C</span>)1,2,4-trichlorobenzene, ({sup <span class="hlt">14</span>}<span class="hlt">C</span>)pentachlorobenzene, and ({sup <span class="hlt">14</span>}<span class="hlt">C</span>)hexachlorobenzene were applied to soils in outdoor lysimeters to a 10-cm depth (2 mg/kg dry soil); barley and cress plants were grown for one vegetation period and analyzed after varying time intervals. The bioaccumulation factors (concentration of radioactive substances in plants divided by that in soils) of barley were higher than those of cress, except for hexachlorobenzene. In barley, bioaccumulation factors increased with decreasing chlorine content of the molecules, except for benzene, whereas in cress hexachlorobenzene exhibited the highest bioaccumulation factor. The conversion ratios of chlorinated benzenes (percentage of conversion products based on total radioactivity in plants) were negatively correlated to the chlorine content of the molecules and, in barley, positively correlated with time; in general, they were higher in barley than in cress. The concentration of radioactive substances in the plants, as well as bioaccumulation factors, decreased with time, except for a slight increase in benzene-derived residues in barley after 125 days. This effect is due to growth dilution. The percentage of radioactivity in barley seeds, based on that in the whole plant, was negatively correlated to the chlorine content of the molecule.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/757416','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/757416"><span id="translatedtitle"><span class="hlt">14</span><span class="hlt">C</span> dating of bone using (gamma) Carboxyglutamic Acid and Carboxyglycine (Aminomalonate)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Southon, J R; Burky, R T; Kirner, D L; Taylor, R E; Hare, P E</p> <p>1999-04-27</p> <p>Radiocarbon determinations have been obtained on {gamma}-carboxyglutamic acid [Gla] and {alpha}-carboxyglycine (aminomalonate) [Am] as well as acid- and base-hydrolyzed total amino acids isolated from a series of fossil bones. As far as they are aware, Am has not been reported previously in fossil bone and neither Gla nor Am {sup <span class="hlt">14</span>}<span class="hlt">C</span> values have been measured previously. Interest in Gla, an amino acid found in the non-collagen proteins osteocalcin and matrix Gla-protein (MGP), proceeds from the suggestion that it may be preferentially retained and more resistant to diagenetic contamination affecting {sup <span class="hlt">14</span>}<span class="hlt">C</span> values in bones exhibiting low and trace amounts of collagen. The data do not support these suggestions. The suite of bones examined showed a general tendency for total amino acid and Gla concentrations to decrease in concert. Even for bones retaining significant amounts of collagen, Gla (and Am extracts) can yield {sup <span class="hlt">14</span>}<span class="hlt">C</span> values discordant with their expected age and with {sup <span class="hlt">14</span>}<span class="hlt">C</span> values obtained on total amino-acid fractions isolated from the same bone sample.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5731265','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5731265"><span id="translatedtitle">Pharmacodynamic behavior of (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)acridine in the cricket Acheta domesticus (L. )</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Walton, B.T.; Maggart, E.F. Jr.</p> <p>1981-11-01</p> <p>Cuticular and gastrointestinal penetration, in vivo metabolism, and excretion of (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)acridine were investigated in the nymphal cricket Acheta domesticus (L.) to find a pharmacodynamic basis for this insect's differential susceptibility to acridine at different life stages. Topically applied (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)acridine readily penetrated the cuticular exoskeleton of nymphs (half-time of penetration, 48 min). Radiolabeled compounds appeared in the hemolymph within 0.5 h after ingestion of (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)acridine and continued to move across the gut wall for 7.5 h. The biological half-time was 18 h and the rate constant for elimination was 0.039 h/sup -1/ after ingestion. Within 5 d after dosing, 97% of the dose was excreted. Several metabolites were present in the feces of nymphs fed (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)acridine, and less than 13% of the extractable radioactivity was parent compound. The cuticule and the gastrointestinal tract proved to be ineffective barriers to acridine entry in A. domesticus. However, the ability to readily metabolize and excrete acridine probably contributes to the higher acridine tolerance observed in the nymphs and adults than in the eggs, which are susceptible to toxic effects. Acridine is found in many coal and synthetic fuel by-products.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70021139','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70021139"><span id="translatedtitle">Anaerobic oxidation of [1,2-<span class="hlt">14</span><span class="hlt">C</span>]dichloroethene under Mn(IV)-reducing conditions</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Bradley, P.M.; Landmeyer, J.E.; Dinicola, R.S.</p> <p>1998-01-01</p> <p>Anaerobic oxidation of [1,2-<span class="hlt">14</span><span class="hlt">C</span>]dichloroethene to14CO2 under Mn(IV)-reducing conditions was demonstrated. The results indicate that oxidative degradation of partially chlorinated solvents like dichloroethene can be significant even under anoxic conditions and demonstrate the potential importance of Mn(IV) reduction for remediation of chlorinated groundwater contaminants.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=249316','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=249316"><span id="translatedtitle">Uptake and transformation of soil [<span class="hlt">14</span><span class="hlt">C</span>]-trinitrotoluene by cool-season grasses</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>This study investigated the fate and uptake of [<span class="hlt">14</span><span class="hlt">C</span>]-TNT from soil into orchardgrass (Dactylis glomerata), perennial ryegrass (Lolium perenne) and tall fescue (Festuca arundinacea) over a one year period in a greenhouse-controlled environment. Pots (n=4 for each grass, containing 10 mg cold TNT/kg s...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=373535','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=373535"><span id="translatedtitle">Decomposition of [<span class="hlt">14</span><span class="hlt">C</span>]Lignocelluloses of Spartina alterniflora and a Comparison with Field Experiments</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wilson, John O.</p> <p>1985-01-01</p> <p>Decomposition of lignocelluloses from Spartina alterniflora in salt-marsh sediments was measured by using <span class="hlt">14</span><span class="hlt">C</span>-labeled compounds. Rates of decomposition were fastest in the first 4 days of incubation and declined later. Lignins labeled in side chains were mineralized slightly faster than uniformly labeled lignins; 12% of the [side chain-<span class="hlt">14</span><span class="hlt">C</span>]lignin-labeled lignocellulose was mineralized after 816 h of incubation, whereas only 8% of the [U-<span class="hlt">14</span><span class="hlt">C</span>]lignin-labeled lignocelluloses were degraded during this period. The carbohydrate moiety within the lignocellulose complex was degraded about four times faster than the lignin moiety; after 816 h of incubation, 29 to 37% of the carbohydrate moiety had been mineralized. Changes in concentration of lignin and cellulose in litter of S. alterniflora were followed over 2 years of decay. Cellulose disappeared from litter more rapidly than lignin; 50% of the initial content of cellulose was lost after 130 days, whereas lignin required 330 to 380 days for 50% loss. The slow loss of lignin compared with other litter components resulted in a progressive enrichment of litter in lignin content. The rates of mineralization of [<span class="hlt">14</span><span class="hlt">C</span>]lignocelluloses in marsh sediments were similar to the rates of lignocellulose decomposition in litter on the marsh. PMID:16346741</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/248116','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/248116"><span id="translatedtitle">Investigation of {sup <span class="hlt">14</span>}<span class="hlt">C</span> release in an engineered low-level waste disposal facility</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Yim, M.S.; Simonson, S.A.; Sullivan, T.M.</p> <p>1996-05-01</p> <p>Atmospheric releases of {sup <span class="hlt">14</span>}<span class="hlt">C</span> from a generic engineered low-level waste (LLW) disposal facility and its radiological impacts are investigated. A computer model that describes microbial gas generation and the transport has been developed and used to analyze the generation of {sup <span class="hlt">14</span>}<span class="hlt">C</span> contaminated gases and subsequent migration in a facility. Models are based on a chemical kinetic description of aerobic and anaerobic decomposition of organic materials coupled with attending models of oxygen transport and consumption within waste containers in a facility. Effects of radiolysis on gas generation are addressed based on the estimated dose rate for class B and C wastes. Estimates predict that annual atmospheric release of {sup <span class="hlt">14</span>}<span class="hlt">C</span> due to atmospheric pressure variations could range between {approximately}2.6 {times} 10{sup 8} and 5.5 {times} 10{sup 11} Bq as a result of microbial gas generation based on a volume of 48 000 m{sup 3} LLW disposed in a facility. The associated dose to a maximally exposed individual is estimated to be dominated by ingestion pathway and strongly depends on the fraction of the food imported from an uncontaminated outside area. Dose rates are expected to be <0.04 mSv/yr, considering a reasonable distance between the facility and the exposed population. The depletion through airborne releases of {sup <span class="hlt">14</span>}<span class="hlt">C</span> inventory that is available for transport through other pathways is not expected to be a significant issue.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007JQS....22...37N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007JQS....22...37N"><span id="translatedtitle">Test of AMS <span class="hlt">14</span><span class="hlt">C</span> dating of pollen concentrates using tephrochronology</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Newnham, Rewi M.; Vandergoes, Marcus J.; Garnett, Mark H.; Lowe, David J.; Prior, Christine; Almond, Peter C.</p> <p>2007-01-01</p> <p>Previous attempts to radiocarbon date sediments >10 kyr from the high rainfall region of Westland, New Zealand, a critical location for investigation of interhemispheric patterns of climate change, have been problematic. This study, building on recent work by Vandergoes and Prior ([2003]), shows that AMS <span class="hlt">14</span><span class="hlt">C</span> dating of pollen concentrates has potential to provide more reliable ages than other sediment constituents, including plant macrofossils. The method was applied to sediments from three sites containing the 22.6k <span class="hlt">14</span><span class="hlt">C</span> yr Kawakawa Tephra, which provided an independent test of the <span class="hlt">14</span><span class="hlt">C</span> ages. Although some minor laboratory contamination was detected in tests on background standards, the modelled relationship between sample mass and measured <span class="hlt">14</span><span class="hlt">C</span> content permitted an appropriate correction to be determined. Improved pollen concentrations derived by density separation between 1.4 and 1.2 specific gravity and sieving in the range 10-50 m provided either older ages than other fractions of the same sample or, where in situ contamination was not evident, equivalent ages. Differences in degree of in situ contamination between depositional environments indicated that, in Westland, lake sites may be less susceptible to contamination by younger carbon than peat sites, where this process may be facilitated by root penetration into underlying sediments. Copyright</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=541727','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=541727"><span id="translatedtitle">Movement of <span class="hlt">14</span><span class="hlt">C</span>-labeled Sugars into Kernels of Wheat (Triticum aestivum L.) 1</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Sakri, Faisal A. K.; Shannon, Jack C.</p> <p>1975-01-01</p> <p>An anatomical study of wheat (Triticum aestivum L.) kernels 14 days after anthesis revealed that the tracheary elements of the pericarp vascular bundle are not in direct continuity with those of the rachilla. The phloem was continuous from the rachilla into the crease of the pericarp. Shortly after exposure of the flag leaf to 14CO2, relatively high proportion of the <span class="hlt">14</span><span class="hlt">C</span> extracted from the pericarp and endosperm was found in glucose and fructose. With additional time, the percentage of <span class="hlt">14</span><span class="hlt">C</span> in the monosaccharides declined and that in sucrose increased to a maximum 3 hours after 14CO2 exposure. The monosaccharides comprised about one-half of the soluble sugars extracted from the pericarp. Based on these observations, it appeared that sucrose hydrolysis might be prerequisite to sugar movement from the terminal phloem elements in the pericarp and into the endosperm. However, when <span class="hlt">14</span><span class="hlt">C</span>-fructosyl-sucrose was injected into the peduncle, there was little additional randomization of the <span class="hlt">14</span><span class="hlt">C</span> between the glucose and fructose moieties of sucrose extracted from the pericarp and endosperm compared to the rachis sucrose. If we assume that injected sucose was transported to the kernels via the phloem, then either sucrose moves out of the terminal phloem elements in the pericarp and into the endosperm unaltered, or if hydrolysis and resynthesis are a prerequisite to transport into the endosperm, the products of hydrolysis are not freely available for isomerization. Images PMID:16659185</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5126039','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5126039"><span id="translatedtitle">Enzymatic aryl-O-methyl-/sup <span class="hlt">14</span>/<span class="hlt">C</span> labeling of model lignin monomers</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Frazer, A.C.; Bossert, I.; Young, L.Y.</p> <p>1986-01-01</p> <p>Aryl-O-methyl ethers are abundant in aerobic and anaerobic environments. In particular, lignin is composed of units of this type. Lignin monomers specifically radiolabeled in methoxy, side chain, and ring carbons have been synthesized by chemical procedures and are important in studies of lignin synthesis and degradation, humus formation, and microbial O-demethylation. In this paper attention is drawn to an enzymatic procedure for preparing O-methyl-/sup <span class="hlt">14</span>/<span class="hlt">C</span>-labeled aromatic lignin monomers which has not previously been exploited in microbial ecology and physiology studies and which has several advantages compared with chemical synthesis procedures. O-(methyl-/sup <span class="hlt">14</span>/<span class="hlt">C</span>)vanillic and O-(methyl-/sup <span class="hlt">14</span>/<span class="hlt">C</span>)ferulic acids were prepared with S-(methyl-/sup <span class="hlt">14</span>/<span class="hlt">C</span>)adenosyl-L-methionine as the methyl donor, using commercially obtained porcine liver catechol-O-methyltransferase (EC 2.1.1.6). The specific activity of the methylated products was the same as that of the methyl donor, a maximum of about 58 ..mu..Ci/..mu..mol, and the yields were 42% (vanillate) and 35% (ferulate). Thus lignin monomers are readily prepared as O-methylated products of the catechol-O-methyltransferase reaction and, with this enzyme method of preparation, would be more widely available than labeled compounds which require chemical synthesis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27602486','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27602486"><span id="translatedtitle">Synthetic Studies toward the C<span class="hlt">14</span>-<span class="hlt">C</span>29 Fragment of Mirabalin.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cornil, Johan; Echeverria, Pierre-Georges; Reymond, Sébastien; Phansavath, Phannarath; Ratovelomanana-Vidal, Virginie; Guérinot, Amandine; Cossy, Janine</p> <p>2016-09-16</p> <p>A convergent synthesis of one isomer of the C<span class="hlt">14</span>-<span class="hlt">C</span>29 fragment of mirabalin is disclosed. The key steps include a Marshall allenylation, a Mukaiyama aldol reaction and a Crimmins aldolization, which allow the control of 10 out of 25 stereogenic centers present in the molecule. PMID:27602486</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.6697F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.6697F"><span id="translatedtitle">The application of in situ <span class="hlt">14</span><span class="hlt">C</span> to Holocene terrestrial Antarctic ice-sheet reconstruction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fogwill, Christopher; Turney, Christian; Hippe, Kristina; Rood, Dylan; Golledge, Nick; Wacker, Lukas; Wieler, Rainer</p> <p>2013-04-01</p> <p>Determining detailed Holocene ice-sheet behaviour in Antarctica is critical for understanding and predicting likely dynamic responses of ice sheets to future climate change. However, to date terrestrial studies using in situ cosmogenic isotopes have struggled to overcome inheritance issues in this cold-based ice setting. Here we present new terrestrial geological constraints that take advantage of recent technological developments in the extraction and measurement of in situ cosmogenic radiocarbon (<span class="hlt">14</span><span class="hlt">C</span>)- a cosmogenic nuclide with a considerably shorter half-life than that of 10Be (10Be: 1.36x103 kyr; <span class="hlt">14</span><span class="hlt">C</span>: 5.73 kyr) - to assess the potential influence of prior exposure or recycling of glacial erratics and therefore improve reconstructions of past ice-sheet surface profile changes. Glacial erratics were sampled from steep exposed bedrock surfaces in the Ellsworth Mountains overlooking the Weddell Sea, serving as 'dipsticks' that allow us to reconstruct past surface elevation changes in the Rutford Ice Stream as it decayed through the Holocene. Our in situ <span class="hlt">14</span><span class="hlt">C</span> analysis reveals a complex relationship, reflecting inheritance and burial, in samples that record anomalously 'old' apparent 10Be exposure ages from previous exposure. Our results enable us to test and refine previous interpretations and thereby reduce chronological uncertainties in Holocene ice-sheet change in this sector of Antarctica, demonstrating the exiting potential of in situ <span class="hlt">14</span><span class="hlt">C</span> in ice-sheet reconstruction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5233266','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5233266"><span id="translatedtitle">Metabolism of U/sup <span class="hlt">14</span>/<span class="hlt">C</span> palmitic and 1-/sup <span class="hlt">14</span>/<span class="hlt">C</span> caproic acids by lettuce seeds during early germination</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Salon, C.; Raymond, P.; Pradet, A.</p> <p>1986-04-01</p> <p>Germinating lettuce embryos (before radicule emergence) were fed with either U/sup <span class="hlt">14</span>/<span class="hlt">C</span> palmitic acid or 1/sup <span class="hlt">14</span>/<span class="hlt">C</span> caproic acid until a metabolic steady state was reached. The bulk of labelled caproate was evolved as respiratory CO/sub 2/ (52%) and incorporated into organic and amino acids (38%) and only a small part incorporated into lipids whereas most of labelled palmitic acid was found into lipids (92%) and only 8% evolved as CO/sub 2/ and incorporated into organic and amino acids. The label distribution at steady state in intermediates linked to the T.C.A. cycle was interpreted using a metabolic model. They found that the two fatty acids were degraded by ..beta..-oxidation and incorporated into the T.C.A. cycle as acetylCoA suggesting that ..beta..-oxidation is located in the mitochondria. The results also indicate that lipids contribute for at least 90% to the carbon supply to respiration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.B33B0413C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.B33B0413C"><span id="translatedtitle">Using <span class="hlt">14</span><span class="hlt">C</span> to investigate Methane Production and DOC Reactivity in Northern Peatlands</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Corbett, J.; Chanton, J.; Glaser, P.; Burdige, D.; Siegel, D.; Cooper, W.</p> <p>2008-12-01</p> <p>We found a consistent distribution pattern for radiocarbon in dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), and methane replicated across spatial and temporal scales in northern peatlands from Minnesota to Alaska. The <span class="hlt">14</span><span class="hlt">C</span> content of DOC is relatively modern throughout the peat column, to depths of 3 meters. In sedge-dominated peatlands, the <span class="hlt">14</span><span class="hlt">C</span> content of the products of respiration, CH4 and DIC are essentially the same, and are similar to that of DOC. In Sphagnum-woody plant dominated peatlands with few sedges, however, the respiration products are similar but intermediate between the <span class="hlt">14</span><span class="hlt">C</span> content of the solid-phase peat and the DOC. Preliminary data indicates qualitative differences in the pore-water DOC depending on the extent of sedge cover, consistent with the hypothesis that the DOC in sedge-dominated peatlands is more reactive than DOC in peatlands where Sphagnum or other vascular plants dominate. These data are supported by molecular-level analysis of DOC by ultrahigh resolution mass spectrometry which suggests dramatic changes with depth in the composition of DOC in the sedge-dominated peatland porewaters but not in porewaters where Sphagnum dominates. The higher reactivity of DOC from sedge- dominated peatlands may be a function of either different source materials or environmental factors that are related to the abundance of sedges in peatlands. To further investigate the reactivity of peat DOC in anaerobic methane producing environments, we are conducting size fractionation experiments for both the bog and fen samples. We will analyze resulting size fractions of DOC for radiocarbon. Previous research has shown that microorganisms tend to prefer HMW DOC to LMW DOC. Due to this, we believe that LMW DOC from both the bogs and the fens will result in radiocarbon values that are more depleted in <span class="hlt">14</span><span class="hlt">C</span> relative to HMW DOC. We hypothesize that the HMW DOC from the bogs will show depletion in <span class="hlt">14</span><span class="hlt">C</span> relative to HMW DOC in the fens. We further</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.184..151K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.184..151K"><span id="translatedtitle">New constraints on the relationship between <span class="hlt">26</span><span class="hlt">Al</span> and oxygen, calcium, and titanium isotopic variation in the early Solar System from a multielement isotopic study of spinel-hibonite inclusions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kööp, Levke; Nakashima, Daisuke; Heck, Philipp R.; Kita, Noriko T.; Tenner, Travis J.; Krot, Alexander N.; Nagashima, Kazuhide; Park, Changkun; Davis, Andrew M.</p> <p>2016-07-01</p> <p>We report oxygen, calcium, titanium and <span class="hlt">26</span><span class="hlt">Al</span>-26Mg isotope systematics for spinel-hibonite inclusions (SHIBs), a class of calcium-aluminum-rich inclusions (CAI) common in CM chondrites. In contrast to previous studies, our analyses of 33 SHIBs and four SHIB-related objects obtained with high spatial resolution demonstrate that these CAIs have a uniform Δ17O value of approximately -23‰, similar to many other mineralogically pristine CAIs from unmetamorphosed chondrites (e.g., CR, CV, and Acfer 094). Five SHIBs studied for calcium and titanium isotopes have no resolvable anomalies beyond 3σ uncertainties. This suggests that nucleosynthetic anomalies in the refractory elements had been significantly diluted in the environment where SHIBs with uniform Δ17O formed. We established internal <span class="hlt">26</span><span class="hlt">Al</span>-26Mg isochrons for eight SHIBs and found that seven of these formed with uniformly high levels of <span class="hlt">26</span><span class="hlt">Al</span> (a multi-CAI mineral isochron yields an initial <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratio of ∼4.8 × 10-5), but one SHIB has a smaller initial <span class="hlt">26</span><span class="hlt">Al</span>/27Al of ∼ 2.5 × 10-5, indicating variation in <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratios when SHIBs formed. The uniform calcium, titanium and oxygen isotopic characteristics found in SHIBs with both high and low initial <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratios allow for two interpretations. (1) If subcanonical initial <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratios in SHIBs are due to early formation, as suggested by Liu et al. (2012), our data would indicate that the CAI formation region had achieved a high degree of isotopic homogeneity in oxygen and refractory elements before a homogeneous distribution of <span class="hlt">26</span><span class="hlt">Al</span> was achieved. (2) Alternatively, if subcanonical ratios were the result of <span class="hlt">26</span><span class="hlt">Al</span>-26Mg system resetting, the clustering of SHIBs at a Δ17O value of ∼-23‰ would imply that a 16O-rich gaseous reservoir existed in the nebula until at least ∼0.7 Ma after the formation of the majority of CAIs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=91263','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=91263"><span id="translatedtitle">Formation of Bound Residues during Microbial Degradation of [<span class="hlt">14</span><span class="hlt">C</span>]Anthracene in Soil</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kästner, M.; Streibich, S.; Beyrer, M.; Richnow, H. H.; Fritsche, W.</p> <p>1999-01-01</p> <p>Carbon partitioning and residue formation during microbial degradation of polycyclic aromatic hydrocarbons (PAH) in soil and soil-compost mixtures were examined by using [<span class="hlt">14</span><span class="hlt">C</span>]anthracenes labeled at different positions. In native soil 43.8% of [9-<span class="hlt">14</span><span class="hlt">C</span>]anthracene was mineralized by the autochthonous microflora and 45.4% was transformed into bound residues within 176 days. Addition of compost increased the metabolism (67.2% of the anthracene was mineralized) and decreased the residue formation (20.7% of the anthracene was transformed). Thus, the higher organic carbon content after compost was added did not increase the level of residue formation. [<span class="hlt">14</span><span class="hlt">C</span>]anthracene labeled at position 1,2,3,4,4a,5a was metabolized more rapidly and resulted in formation of higher levels of residues (28.5%) by the soil-compost mixture than [<span class="hlt">14</span><span class="hlt">C</span>]anthracene radiolabeled at position C-9 (20.7%). Two phases of residue formation were observed in the experiments. In the first phase the original compound was sequestered in the soil, as indicated by its limited extractability. In the second phase metabolites were incorporated into humic substances after microbial degradation of the PAH (biogenic residue formation). PAH metabolites undergo oxidative coupling to phenolic compounds to form nonhydrolyzable humic substance-like macromolecules. We found indications that monomeric educts are coupled by C-C- or either bonds. Hydrolyzable ester bonds or sorption of the parent compounds plays a minor role in residue formation. Moreover, experiments performed with 14CO2 revealed that residues may arise from CO2 in the soil in amounts typical for anthracene biodegradation. The extent of residue formation depends on the metabolic capacity of the soil microflora and the characteristics of the soil. The position of the <span class="hlt">14</span><span class="hlt">C</span> label is another important factor which controls mineralization and residue formation from metabolized compounds. PMID:10223966</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AtmRe.164..297C&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AtmRe.164..297C&link_type=ABSTRACT"><span id="translatedtitle">Characteristics of <span class="hlt">14</span><span class="hlt">C</span> and 13C of carbonate aerosols in dust storm events in China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Bing; Jie, Dongmei; Shi, Meinan; Gao, Pan; Shen, Zhenxing; Uchida, Masao; Zhou, Liping; Liu, Kexin; Hu, Ke; Kitagawa, Hiroyuki</p> <p>2015-10-01</p> <p>In contrast with its decrease in western China deserts, the dust storm event in eastern China, Korea, and Japan shows an increase in frequency. Although the drylands in northeastern China have been recognized as an important dust source, the relative contributions of dust transport from the drylands and deserts are inconclusive, thus the quantification of dust storm sources in downwind area remains a challenge. We measured the <span class="hlt">14</span><span class="hlt">C</span> and 13C contents in carbonates of dust samples from six sites in China, which were collected for the duration of dust storm events in drylands, deserts, and urban areas. The δ13C of the dryland dust samples considerably varied in a range of - 9.7 to - 5.0‰, which partly overlapped the desert dust carbonate δ13C ranges. The <span class="hlt">14</span><span class="hlt">C</span> content of the dryland dust carbonates showed a narrow range of 60.9 ± 4.0 (as an average and 1 SD of five samples) percent modern carbon (pMC), indicating the enrichment of modern carbonate. Dust samples in desert regions contained relatively aged carbonates with the depleting <span class="hlt">14</span><span class="hlt">C</span> showing of 28.8 ± 3.3 pMC. After the long-range transport of the western China desert dust plume, the carbonates collected at the southern China remained the depletion of <span class="hlt">14</span><span class="hlt">C</span> (33.5 ± 5.3 pMC) as in the desert regions. On the other hand, the samples of dust storm events at the urban areas of eastern China showed an enrichment of <span class="hlt">14</span><span class="hlt">C</span> contents (46.2 ± 5.0 pMC, n = 7), which might be explained by the stronger contribution of modern-carbonate-rich dryland dust.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3950335','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3950335"><span id="translatedtitle">The Fate of Inhaled <span class="hlt">14</span><span class="hlt">C</span>-labelled PCB11 and its Metabolites In Vivo1</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Hu, Xin; Adamcakova-Dodd, Andrea; Thorne, Peter S.</p> <p>2014-01-01</p> <p>Background The production ban of polychlorinated biphenyl (PCB) technical mixtures has left the erroneous impression that PCBs exist only as legacy pollutants. Some lower-chlorinated PCBs are still being produced and contaminate both indoor and ambient air. Objectives To inform PCB risk assessment, we characterized lung uptake, distribution, metabolism and excretion of PCB11 as a signature compound for these airborne non-legacy PCBs. Methods After delivering [<span class="hlt">14</span><span class="hlt">C</span>]PCB11 to the lungs of male rats, radioactivity in 34 major tissues and 5 digestive matter compartments was measured at 12, 25, 50, 100, 200 and 720 min postexposure, during which time the excreta and exhaled air were also collected. [<span class="hlt">14</span><span class="hlt">C</span>]PCB11 and metabolites in liver, blood, digestive matter, urine and adipose tissues were extracted separately to establish the metabolic profile of the disposition. Results [<span class="hlt">14</span><span class="hlt">C</span>]PCB11 was distributed rapidly to all tissues after 99.8% pulmonary uptake and quickly underwent extensive metabolism. The major tissue deposition of [<span class="hlt">14</span><span class="hlt">C</span>]PCB11 and metabolites translocated from liver, blood and muscle to skin and adipose tissue 200 min postexposure, while over 50% of administered dose was discharged via urine and feces within 12 h. Elimination of the [<span class="hlt">14</span><span class="hlt">C</span>]PCB11 and metabolites consisted of an initial fast phase (t½ = 9-33 min) and a slower clearance phase to low concentrations. Phase II metabolites dominated in liver, blood and excreta after 25 min postexposure. Conclusions This study shows that PCB11 is completely absorbed after inhalation exposure and is rapidly eliminated from most tissues. Phase II metabolites dominated with a slower elimination rate than the PCB11 or phase I metabolites and thus can best serve as urine biomarkers of exposure. PMID:24275706</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004GeCoA..68.2509M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004GeCoA..68.2509M"><span id="translatedtitle">Recent chronologies for tree rings and terrestrial archives using <span class="hlt">14</span><span class="hlt">C</span> bomb fallout history</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McGee, E. J.; Gallagher, D.; Mitchell, P. I.; Baillie, M.; Brown, D.; Keogh, S. M.</p> <p>2004-06-01</p> <p>Tree rings representing the period from the mid-1950s up to 2001 were studied as part of an investigation of anthropogenic radionuclide input to terrestrial systems. A live specimen of Pinus sylvestris from the east coast of Ireland was felled, sampled and analysed for comparison with a similar tree felled close to the Atlantic seaboard on the west coast of Ireland. Data for the tree ring sequences were examined relative to the radionuclide content of peat profiles sampled in close proximity to the locations of the studied Pine trees. The data indicate that <span class="hlt">14</span><span class="hlt">C</span> concentrations in tree ring sequences from the east and west coasts of Ireland are virtually identical. The sequences show maximum <span class="hlt">14</span><span class="hlt">C</span> concentrations (185 and 189 pMC at east and west coast sites, respectively) that correspond closely with published data for atmospheric levels during the height of the nuclear weapons test period (1945-1980). The tree ring count for the specimen from the east coast places the <span class="hlt">14</span><span class="hlt">C</span> peak precisely at 1964, the year following the known peak in atmospheric concentrations due to above ground testing of nuclear weapons. However, <span class="hlt">14</span><span class="hlt">C</span> data show that simple ring counting of the west coast tree did not provide an accurate chronology. The data demonstrate the importance of applying dendrodating techniques using replicated site chronologies, and the value of the <span class="hlt">14</span><span class="hlt">C</span> bomb fallout curve for the construction of recent chronologies. Data show no evidence of enhanced uptake at the east coast that might suggest incorporation of output from the Sellafield nuclear complex or from the release of radioactivity resulting from an accidental fire at the plant in 1957.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/346826','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/346826"><span id="translatedtitle">Formation of bound residues during microbial degradation of [{sup <span class="hlt">14</span>}<span class="hlt">C</span>]anthracene in soil</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kaestner, M.; Streibich, S.; Beyrer, M.; Fritsche, W.; Richnow, H.H.</p> <p>1999-05-01</p> <p>Carbon partitioning and residue formation during microbial degradation of polycyclic aromatic hydrocarbons (PAH) in soil and soil-compost mixtures were examined by using [{sup <span class="hlt">14</span>}<span class="hlt">C</span>]anthracenes labeled at different positions. In native soil 43.8% of [9-{sup <span class="hlt">14</span>}<span class="hlt">C</span>]anthracene was mineralized by the autochthonous microflora and 45.4% was transformed into bound residues within 176 days. Addition of compost increased the metabolism and decreased the residue formation (20.7% of the anthracene was transformed). Thus, the higher organic carbon content after compost was added did not increase the level of residue formation. [{sup <span class="hlt">14</span>}<span class="hlt">C</span>]anthracene labeled at position 1,2,3,4,4a,5a was metabolized more rapidly and resulted in formation of higher levels of residues (28.5%) by the soil-compost mixture than [{sup <span class="hlt">14</span>}<span class="hlt">C</span>]anthracene radiolabeled at position C-9 (20.7%). Two phases of residue formation were observed in the experiments. In the first phase the original compound was sequestered in the soil, as indicated by its limited extractability. In the second phase metabolites were incorporated into humic substances after microbial degradation of the PAH (biogenic residue formation). PAH metabolites undergo oxidative coupling to phenolic compounds to form nonhydrolyzable humic substance-like macromolecules. The authors found indications that monomeric educts are coupled by C-C- or either bonds. Hydrolyzable ester bonds or sorption of the parent compounds plays a minor role in residue formation. Moreover, experiments performed with {sup 14}CO{sub 2} revealed that residues may arise from CO{sub 2} in the soil in amounts typical for anthracene biodegradation. The extent of residue formation depends on the metabolic capacity of the soil microflora and the characteristics of the soil. The position of the {sup <span class="hlt">14</span>}<span class="hlt">C</span> label is another important factor which controls mineralization and residue formation from metabolized compounds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/881059','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/881059"><span id="translatedtitle">Reconciling Change in Oi-Horizon <span class="hlt">14</span><span class="hlt">C</span> With Mass Loss for an Oak Forest</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hanson, P J; Swanston, C W; Garten, Jr., C T; Todd, D E; Trumbore, S E</p> <p>2005-06-27</p> <p>First-year litter decomposition was estimated for an upland-oak forest ecosystem using enrichment or dilution of the {sup <span class="hlt">14</span>}<span class="hlt">C</span>-signature of the Oi-horizon. These isotopically-based mass-loss estimates were contrasted with measured mass-loss rates from past litterbag studies. Mass-loss derived from changes in the {sup <span class="hlt">14</span>}<span class="hlt">C</span>-signature of the Oi-horizon suggested mean mass loss over 9 months of 45% which was higher than the corresponding 9-month rate extrapolated from litterbag studies ({approx}35%). Greater mass loss was expected from the isotopic approach because litterbags are known to limit mass loss processes driven by soil macrofauna (e.g., fragmentation and comminution). Although the {sup <span class="hlt">14</span>}<span class="hlt">C</span>-isotope approach offers the advantage of being a non-invasive method, it exhibited high variability that undermined its utility as an alternative to routine litterbag mass loss methods. However, the {sup <span class="hlt">14</span>}<span class="hlt">C</span> approach measures the residence time of C in the leaf litter, rather than the time it takes for leaves to disappear; hence radiocarbon measures are subject to C immobilization and recycling in the microbial pool, and do not necessarily reflect results from litterbag mass loss. The commonly applied two-compartment isotopic mixing model was appropriate for estimating decomposition from isotopic enrichment of near-background soils, but it produced divergent results for isotopic dilution of a multi-layered system with litter cohorts having independent {sup <span class="hlt">14</span>}<span class="hlt">C</span>-signatures. This discrepancy suggests that cohort-based models are needed to adequately capture the complex processes involved in carbon transport associated with litter mass-loss. Such models will be crucial for predicting intra- and interannual differences in organic horizon decomposition driven by scenarios of climatic change.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27221729','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27221729"><span id="translatedtitle">Pharmacokinetics and excretion of (<span class="hlt">14</span>)<span class="hlt">C</span>-omacetaxine in patients with advanced solid tumors.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nijenhuis, Cynthia M; Hellriegel, Edward; Beijnen, Jos H; Hershock, Diane; Huitema, Alwin D R; Lucas, Luc; Mergui-Roelvink, Marja; Munteanu, Mihaela; Rabinovich-Guilatt, Laura; Robertson, Philmore; Rosing, Hilde; Spiegelstein, Ofer; Schellens, Jan H M</p> <p>2016-10-01</p> <p>Background Omacetaxine mepesuccinate is indicated in adults with chronic myeloid leukemia resistant and/or intolerant to ≥ 2 tyrosine kinase inhibitor treatments. This phase I study assessed the disposition, elimination, and safety of (<span class="hlt">14</span>)<span class="hlt">C</span>-omacetaxine in patients with solid tumors. Methods The study comprised a 7-days pharmacokinetic assessment followed by a treatment period of ≤ six 28-days cycles. A single subcutaneous dose of 1.25 mg/m(2) (<span class="hlt">14</span>)<span class="hlt">C</span>-omacetaxine was administered to six patients. Blood, urine, and feces were collected through 168 h or until radioactivity excreted within 24 h was <1 % of the dose. Total radioactivity (TRA) was measured in all matrices and concentrations of omacetaxine, 4'-desmethylhomoharringtonine (4'-DMHHT), and cephalotaxine were measured in plasma and urine. For each treatment cycle, patients received 1.25 mg/m(2) omacetaxine twice daily for 7 days. Results Mean TRA recovered was approximately 81 % of the dose, with approximately half of the radioactivity recovered in feces and half in urine. Approximately 20 % of the dose was excreted unchanged in urine; cephalotaxine (0.4 % of dose) and 4' DMHHT (9 %) were also present. Plasma concentrations of TRA were higher than the sum of omacetaxine and known metabolites, suggesting the presence of other (<span class="hlt">14</span>)<span class="hlt">C</span>-omacetaxine-derived compounds. Fatigue and anemia were common, consistent with the known toxicity profile of omacetaxine. Conclusion Renal and hepatic processes contribute to the elimination of (<span class="hlt">14</span>)<span class="hlt">C</span>-omacetaxine-derived radioactivity in cancer patients. In addition to omacetaxine and its known metabolites, other (<span class="hlt">14</span>)<span class="hlt">C</span>-omacetaxine-derived materials appear to be present in plasma and urine. Omacetaxine was adequately tolerated, with no new safety signals. PMID:27221729</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21502794','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21502794"><span id="translatedtitle">Role of higher-multipole deformations in exotic {sup <span class="hlt">14</span>}<span class="hlt">C</span> cluster radioactivity</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sawhney, Gudveen; Sharma, Manoj K.; Gupta, Raj K.</p> <p>2011-06-15</p> <p>We have studied nine cases of spontaneous emission of {sup <span class="hlt">14</span>}<span class="hlt">C</span> clusters in the ground-state decays of the same number of parent nuclei from the trans-lead region, specifically from {sup 221}Fr to {sup 226}Th, using the preformed cluster model (PCM) of Gupta and collaborators, with choices of spherical, quadrupole deformation ({beta}{sub 2}) alone, and higher-multipole deformations ({beta}{sub 2}, {beta}{sub 3}, {beta}{sub 4}) with cold ''compact'' orientations {theta}{sup c} of decay products. The calculated {sup <span class="hlt">14</span>}<span class="hlt">C</span> cluster decay half-life times are found to be in nice agreement with experimental data only for the case of higher-multipole deformations ({beta}{sub 2}-{beta}{sub 4}) and {theta}{sup c} orientations of cold elongated configurations. In other words, compared to our earlier study of clusters heavier than {sup <span class="hlt">14</span>}<span class="hlt">C</span>, where the inclusion of {beta}{sub 2} alone, with ''optimum'' orientations, was found to be enough to give the best comparison with data, here for {sup <span class="hlt">14</span>}<span class="hlt">C</span> cluster decay the inclusion of higher-multipole deformations (up to hexadecapole), together with {theta}{sup c} orientations, is found to be essential on the basis of the PCM. Interestingly, whereas both the penetration probability and assault frequency work simply as scaling factors, the preformation probability is strongly influenced by the order of multipole deformations and orientations of nuclei. The possible role of Q value and angular-momentum effects are also considered in reference to {sup <span class="hlt">14</span>}<span class="hlt">C</span> cluster radioactivity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6717639','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6717639"><span id="translatedtitle">Substrate metabolism in isolated rat jejunal epithelium. Analysis using /sup <span class="hlt">14</span>/<span class="hlt">C</span>-radioisotopes</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mallet, R.T.</p> <p>1986-01-01</p> <p>The jejunal epithelium absorbs nutrients from the intestinal lumen and is therefore the initial site for metabolism of these compounds. The purpose of this investigation is to analyze substrate metabolism in a preparation of jejunal epithelium relatively free of other tissues. Novel radioisotopic labelling techniques allow quantitation of substrate metabolism in the TCA cycle, Embden-Meyerhof (glycolytic) pathway, and hexose monophosphate shunt. For example, ratios of /sup 14/CO/sub 2/ production from pairs of /sup <span class="hlt">14</span>/<span class="hlt">C</span>-pyruvate, and /sup <span class="hlt">14</span>/<span class="hlt">C</span>-succinate radioisotopes (CO/sub 2/ ratios) indicate the probability of TCA cycle intermediate efflux to generate compounds other than CO/sub 2/. With (2,3-/sup <span class="hlt">14</span>/<span class="hlt">C</span>)succinate as tracer, the ratio of /sup <span class="hlt">14</span>/<span class="hlt">C</span> in carbon 4 + 5 versus carbon 2 + 3 of citrate, the citrate labelling ratio, equals the probability of TCA intermediate flux to the acetyl CoA-derived portion of citrate versus flux to the oxaloacetate-derived portion. The principal metabolic substrates for the jejunal epithelium are glucose and glutamine. CO/sub 2/ ratios indicate that glutamine uptake and metabolism is partially Na/sup +/-independent, and is saturable, with a half-maximal rate at physiological plasma glutamine concentrations. Glucose metabolism in the jejunal epithelium proceeds almost entirely via the Embden-Meyerhof pathway. Conversion of substrates to multi-carbon products in this tissue allows partial conservation of reduced carbon for further utilization in other tissues. In summary, metabolic modeling based on /sup <span class="hlt">14</span>/<span class="hlt">C</span> labelling ratios is a potentially valuable technique for analysis of metabolic flux patterns in cell preparations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/22720588','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/22720588"><span id="translatedtitle">[Quantifying rice (Oryza sativa L.) photo-assimilated carbon input into soil organic carbon pools following continuous <span class="hlt">14</span><span class="hlt">C</span> labeling].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nie, San-An; Zhou, Ping; Ge, Ti-Da; Tong, Cheng-Li; Xiao, He-Ai; Wu, Jin-Shui; Zhang, Yang-Zhu</p> <p>2012-04-01</p> <p>The microcosm experiment was carried out to quantify the input and distribution of photo-assimilated C into soil C pools by using a <span class="hlt">14</span><span class="hlt">C</span> continuous labeling technique. Destructive samplings of rice (Oryza sativa) were conducted after labeling for 80 days. The allocation of <span class="hlt">14</span><span class="hlt">C</span>-labeled photosynthates in plants and soil C pools such as dissolved organic C (DOC) and microbial biomass C (MBC) in rice-planted soil were examined over the <span class="hlt">14</span><span class="hlt">C</span> labeling span. The amounts of rice shoot and root biomass C was ranged from 1.86 to 5.60 g x pot(-1), 0.46 to 0.78 g x pot(-1) in different tested paddy soils after labeling for 80 days, respectively. The amount of <span class="hlt">14</span><span class="hlt">C</span> in the soil organic C (<span class="hlt">14</span><span class="hlt">C</span>-SOC) was also dependent on the soils, ranged from 114.3 to 348.2 mg x kg(-1), accounting for 5.09% to 6.62% of the rice biomass <span class="hlt">14</span><span class="hlt">C</span>, respectively. The amounts of <span class="hlt">14</span><span class="hlt">C</span> in the dissolved organic C (<span class="hlt">14</span><span class="hlt">C</span>-DOC) and in the microbial biomass C(<span class="hlt">14</span><span class="hlt">C</span>-MBC), as proportions of <span class="hlt">14</span><span class="hlt">C</span>-SOC, were 2.21%-3.54% and 9.72% -17.2%, respectively. The <span class="hlt">14</span><span class="hlt">C</span>-DOC, <span class="hlt">14</span><span class="hlt">C</span>-MBC, and <span class="hlt">14</span><span class="hlt">C</span>-SOC as proportions of total DOC, MBC, and SOC, respectively, were 6.72% -14.64%, 1.70% -7.67%, and 0.73% -1.99%, respectively. Moreover, the distribution and transformation of root-derived C had a greater influence on the dynamics of DOC and MBC than on the dynamics of SOC. Further studies are required to ascertain the functional significance of soil microorganisms (such as C-sequestering bacteria and photosynthetic bacteria) in the paddy system. PMID:22720588</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.H43A1216M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.H43A1216M"><span id="translatedtitle">Pore water dating by 129I: What do <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratio, dissolved 4He concentration, δ37Cl and 129I/127I ratio suggest in the Mobara Gas field, Japan?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mahara, Y.; Ohta, T.; Tokunaga, T.</p> <p>2010-12-01</p> <p>Total 24-brine samples were collected from hot springs and the Mobara gas wells in the Southern Kanto Gas field, where is not only the major production area for dissolved natural gas in Japan but for iodine in the world. Isotopic ratios of 129I/127I and <span class="hlt">36</span><span class="hlt">Cl</span>/Cl, and noble gases concentration dissolved into pore water were measured for estimating residence time of brine. Iodine concentration in brines increases from 10 mg/L in the northern Kanto plain to more than 100 mg/L in the south edge of the gas field, and finally reaches 170 mg/L. In contrast, the isotopic ratio of 129I/127I decreases 5×10-13 in north to 1.7×10-13 in south. Both distributions were presumably controlled by the thickness of the Kazusa group as natural gas reservoirs. The average 129I/127I ratio was estimated to be 2.33 ± 0.11×10-13 at the Mobara area. Average ages of brines are estimated to be 42 Ma by using the initial 129I/127I ratio (1.5×10-12), if the origin of 129I were cosmogenic. On the other hand, we deduced 0.2 - 0.9 Ma as the residence time of brine from comparison with the secular equilibrium <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratio (6.46 ± 2.24×10-15) for the reservoir formation of Pleistocene. The concentration of 4He dissolved in pore water in the bored rock core suggests that residence time of brines vertically ranges 0.12 - 1.05 Ma and it is also harmonized with the formation age (of 0.45 - 2.5 Ma). Furthermore, δ37Cl (- 0.14±0.13 ~ + 0.45±0.07 ‰) in pore water were measured under the chloride concentration increasing 5000 mg/L to 17000 mg/L at the depth from 642 m to 1902 m below the ground surface. The simulating analyses of δ37Cl was conducted under the boundary conditions of washing out by freshwater at the depth of 600 m below the ground surface, chloride concentration gradient of 17000/500 (mg/L/m) and diffusion alone without advection flow during the past 0.12 Ma. The fractionation factor for 35Cl and 37Cl was 1.0012 (Desauliniers et al., 1986). The analyses indicated that the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6993094','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6993094"><span id="translatedtitle">Changes in the level of ( sup <span class="hlt">14</span> <span class="hlt">C</span>)indole-3-acetic acid and ( sup <span class="hlt">14</span> <span class="hlt">C</span>)indoleacetylaspartic acid during root formation in mung bean cuttings. [Vigna radiata</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Norcini, J.G.; Heuser, C.W. )</p> <p>1988-04-01</p> <p>Changes in the levels of ({sup <span class="hlt">14</span>}<span class="hlt">C</span>)indole-3-acetic acid (IAA) and ({sup <span class="hlt">14</span>}<span class="hlt">C</span>)indoleacetylaspartic acid (IAAsp) were examined during adventitious root formation in mung bean (Vigna radiata (L.) R. Wilcz. Berken) stem cuttings. IAAsp was identified by GC-MS as the primary conjugate in IAA-treated cuttings. During root formation in IAA-treated cuttings, the level of ({sup <span class="hlt">14</span>}<span class="hlt">C</span>)IAAsp increased rapidly the first day and then declined; ({sup <span class="hlt">14</span>}<span class="hlt">C</span>)IAA was rapidly metabolized and not detected after 12 hours.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.V53C2287B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.V53C2287B"><span id="translatedtitle">Tree-ring <span class="hlt">14</span><span class="hlt">C</span> and CO2 emissions at Mammoth Mountain and Yellowstone, USA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bergfeld, D.; McGeehin, J. P.; King, J.; Heasler, H.; Evans, W. C.</p> <p>2010-12-01</p> <p>A large pulse of magmatic CO2 began venting through soils on the flanks of Mammoth Mountain CA within months of a local seismic swarm in 1989. Previous workers have shown that the CO2 efflux rate was large enough to kill ~0.5 km2 of forest and cause substantial depletion of <span class="hlt">14</span><span class="hlt">C</span> in the wood of surviving trees at the edges of the kill zones. CO2 efflux at Mammoth Mountain continues to be well-studied, in part because of the obvious link between the seismic swarm and the onset of outgassing. A somewhat similar event apparently occurred a decade previously in the Yellowstone caldera, where we see a record of <span class="hlt">14</span><span class="hlt">C</span> depletion of 10-25% in a tree at Cooking Hillside in the Mud Volcano area. The <span class="hlt">14</span><span class="hlt">C</span> levels in tree core data show that CO2 emissions began to increase during a local seismic swarm in 1978. A huge drop in <span class="hlt">14</span><span class="hlt">C</span> in the 1979 growth ring suggests that CO2 emissions increased about 5-fold over values earlier in the decade. The emissions spike persisted into 1980 but at greatly reduced levels. This event at Mud Volcano occurred in a thermal area long known to emit CO2 gas and was associated with a substantial increase in surface heating and steam emission, in contrast to the case of Mammoth Mountain. However, the two events share some important similarities: increased CO2 emissions began within months of the onset of shallow (<7 km) seismic swarms, emissions peaked within 1-2 years later, and peak emissions are estimated at ~1000 tonnes of CO2 per day. Seismicity in both cases was likely driven by CO2-rich hydrous fluids; intrusion of magma into the shallow crust seems unlikely, particularly at Yellowstone where the youngest intra-caldera lavas are 70 ka. These similarities imply that, while each event has unique attributes, both are more likely variants on a process that may be fairly common in areas of magmatism. Additional tree coring at Mammoth Mountain will allow a direct comparison between <span class="hlt">14</span><span class="hlt">C</span> depletion and annual CO2 flux surveys. Ongoing tree-core <span class="hlt">14</span><span class="hlt">C</span> studies at</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1388337','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1388337"><span id="translatedtitle">Transformation of (sup<span class="hlt">14</span>)<span class="hlt">C</span>-Lignin-Labeled Cell Walls of Wheat by Syntrophococcus sucromutans, Eubacterium oxidoreducens, and Neocallimastix frontalis</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bernard-Vailhe, M. A.; Besle, J. M.; Dore, J.</p> <p>1995-01-01</p> <p>Wheat cell walls, saponified or not, labeled with [U-(sup<span class="hlt">14</span>)<span class="hlt">C</span>]phenylalanine or [O-methyl-(sup<span class="hlt">14</span>)<span class="hlt">C</span>]sinapate were fermented by Neocallimastix frontalis or Syntrophococcus sucromutans plus Eubacterium oxidoreducens or a mixed culture. Phenolics were less solubilized but more transformed by bacteria than by the fungus, and mineralization was slight. S. sucromutans O-demethylated [O-methyl-(sup<span class="hlt">14</span>)<span class="hlt">C</span>]syringyl lignins, yielding labeled acetate. PMID:16534916</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27387810','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27387810"><span id="translatedtitle">Modeling of irradiated graphite (<span class="hlt">14</span>)<span class="hlt">C</span> transfer through engineered barriers of a generic geological repository in crystalline rocks.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Poskas, Povilas; Grigaliuniene, Dalia; Narkuniene, Asta; Kilda, Raimondas; Justinavicius, Darius</p> <p>2016-11-01</p> <p>There are two RBMK-1500 type graphite moderated reactors at the Ignalina nuclear power plant in Lithuania, and they are under decommissioning now. The graphite cannot be disposed of in a near surface repository, because of large amounts of (<span class="hlt">14</span>)<span class="hlt">C</span>. Therefore, disposal of the graphite in a geological repository is a reasonable solution. This study presents evaluation of the (<span class="hlt">14</span>)<span class="hlt">C</span> transfer by the groundwater pathway into the geosphere from the irradiated graphite in a generic geological repository in crystalline rocks and demonstration of the role of the different components of the engineered barrier system by performing local sensitivity analysis. The speciation of the released (<span class="hlt">14</span>)<span class="hlt">C</span> into organic and inorganic compounds as well as the most recent information on (<span class="hlt">14</span>)<span class="hlt">C</span> source term was taken into account. Two alternatives were considered in the analysis: disposal of graphite in containers with encapsulant and without it. It was evaluated that the maximal fractional flux of inorganic (<span class="hlt">14</span>)<span class="hlt">C</span> into the geosphere can vary from 10(-11)y(-1) (for non-encapsulated graphite) to 10(-12)y(-1) (for encapsulated graphite) while of organic (<span class="hlt">14</span>)<span class="hlt">C</span> it was about 10(-3)y(-1) of its inventory. Such difference demonstrates that investigations on the (<span class="hlt">14</span>)<span class="hlt">C</span> inventory and chemical form in which it is released are especially important. The parameter with the highest influence on the maximal flux into the geosphere for inorganic (<span class="hlt">14</span>)<span class="hlt">C</span> transfer was the sorption coefficient in the backfill and for organic (<span class="hlt">14</span>)<span class="hlt">C</span> transfer - the backfill hydraulic conductivity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040112229&hterms=phenylalanine&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dphenylalanine','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040112229&hterms=phenylalanine&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dphenylalanine"><span id="translatedtitle">Utilization of [<span class="hlt">14</span><span class="hlt">C</span>]phenylalanine derived from arylphorin or free amino acid in Manduca sexta pharate adults</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wu, M.; Tischler, M. E.</p> <p>1995-01-01</p> <p>The role of arylphorin as a storage protein was studied using <span class="hlt">14</span><span class="hlt">C</span>-arylphorin. <span class="hlt">14</span><span class="hlt">C</span>-arylphorin was produced optimally by incubating one-half fat body from Manduca sexta fifth instar larvae at 22 degrees C for 24 h, in 1 ml of medium containing amino acids at 25% of their physiological concentration with [U-<span class="hlt">14</span><span class="hlt">C</span>]-phenylalanine (phe) provided initially without nonlabeled phenylalanine. Nonlabeled phe was provided after 1 h at 16% of its physiological concentration. The specific activity of <span class="hlt">14</span><span class="hlt">C</span>-arylphorin produced in vitro was 30 times greater than that generated in vivo. Injection of <span class="hlt">14</span><span class="hlt">C</span>-arylphorin into pharate adults was used to study the distribution of <span class="hlt">14</span><span class="hlt">C</span>-phe derived from this protein into 14CO2 and tissues for comparison with injection of free <span class="hlt">14</span><span class="hlt">C</span>-phe during the middle (days 6 to 12 pharate adult) and late (days 12 to 17 pharate adult) stages of adult development. Appearance of 14CO2 from <span class="hlt">14</span><span class="hlt">C</span>-arylphorin as compared to <span class="hlt">14</span><span class="hlt">C</span>-phenylalanine showed a slower time course during both the middle and late stages of development, in keeping with the time needed for degradation of the protein. In accord with faster phe turnover near the end of adult development, total 14CO2 production was greater and the retention of <span class="hlt">14</span><span class="hlt">C</span> in hemolymph and fat body was less compared to the middle stage of development regardless of whether <span class="hlt">14</span><span class="hlt">C</span>-arylphorin or <span class="hlt">14</span><span class="hlt">C</span>-phe was injected. In the middle stage of development, the appearance of <span class="hlt">14</span><span class="hlt">C</span> in the cuticle and head parts was greater, whereas incorporation into abdomen and thorax was less than during the late stage of development. Since the pattern of <span class="hlt">14</span><span class="hlt">C</span> distribution from <span class="hlt">14</span><span class="hlt">C</span>-arylphorin and <span class="hlt">14</span><span class="hlt">C</span>-phe was similar, one major function of arylphorin must be as a storage protein replenishing the supply of free amino acids used for synthesis of adult tissues. These results also suggest a limited contribution of M. sexta arylphorin to formation of the cuticle subsequent to day-6 pharate adult.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19909730','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19909730"><span id="translatedtitle">Remarkable increase in <span class="hlt">14</span><span class="hlt">C</span>-acetate uptake in an epilepsy model rat brain induced by lithium-pilocarpine.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hosoi, Rie; Kitano, Daisuke; Momosaki, Sotaro; Kuse, Kenji; Gee, Antony; Inoue, Osamu</p> <p>2010-01-22</p> <p>The present study demonstrates changes in rat brain glial metabolism during the acute phase of epilepsy. Status epilepticus (SE) was induced using the lithium-pilocarpine model. Glial metabolism was measured with (<span class="hlt">14</span>)<span class="hlt">C</span>-acetate. Local cerebral blood flow and glucose metabolism were also measured using (<span class="hlt">14</span>)<span class="hlt">C</span>-N-isopropyl-p-iodoamphetamine (IMP) and (<span class="hlt">14</span>)<span class="hlt">C</span>-2-deoxyglucose (2DG), respectively. At the initiation of the seizure, (<span class="hlt">14</span>)<span class="hlt">C</span>-acetate uptake did not change significantly. However, a marked increase was observed 2 h after the pilocarpine injection in all brain regions studied. The increase of brain uptake was transient, and the maximum enhancement was seen at 2 h after the pilocarpine injection. The increase of (<span class="hlt">14</span>)<span class="hlt">C</span>-acetate uptake was almost to the same degree in all regions, whereas (<span class="hlt">14</span>)<span class="hlt">C</span>-IMP and (<span class="hlt">14</span>)<span class="hlt">C</span>-2DG uptakes showed a heterogeneous increase. In the case of (<span class="hlt">14</span>)<span class="hlt">C</span>-IMP, the highest increase was observed in the thalamus (280%), and a moderate increase (120 to 150%) was seen in the orbital cortex, cingulate cortex and pyriform cortex. (<span class="hlt">14</span>)<span class="hlt">C</span>-2DG uptake increased by 130 to 240% in most regions of the brain, however, an increase of only 40 and 20% was observed in the cerebellum and pons-medulla, respectively. These results demonstrated that glial energy metabolism was markedly enhanced during a prolonged seizure. To our knowledge, this study is the first observation showing large and widespread glial metabolic increases in the rat brain during status epilepticus.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/2303914','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/2303914"><span id="translatedtitle">The metabolism of [<span class="hlt">14</span><span class="hlt">C</span>]beta-carotene and the presence of other carotenoids in rats and monkeys.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Krinsky, N I; Mathews-Roth, M M; Welankiwar, S; Sehgal, P K; Lausen, N C; Russett, M</p> <p>1990-01-01</p> <p>The metabolism of beta-carotene has been studied in both rats and Rhesus monkeys, following the oral administration of [<span class="hlt">14</span><span class="hlt">C</span>]beta-carotene in olive oil supplemented with 1 mg/mL alpha-tocopherol. In the rats, peak serum accumulation of [<span class="hlt">14</span><span class="hlt">C</span>]retinol occurred 4 h after a single oral dose, but we were not able to detect [<span class="hlt">14</span><span class="hlt">C</span>]beta-carotene in rat sera at any time up to 72 h after dosing. Small amounts of [<span class="hlt">14</span><span class="hlt">C</span>]beta-carotene were found in the livers, although 88-94% of the recovered radioactivity was localized in the retinol fraction after saponification. Although radioactivity was also found in fractions other than beta-carotene and retinol, the amounts were too small to allow characterization. In the monkeys, peak accumulation of [<span class="hlt">14</span><span class="hlt">C</span>]retinol in serum occurred between 8 and 24 h after supplementation. Some [<span class="hlt">14</span><span class="hlt">C</span>]beta-carotene was also present. Most of the absorbed radioactivity was stored in the liver as [<span class="hlt">14</span><span class="hlt">C</span>]retinol, although 2-8% was present as [<span class="hlt">14</span><span class="hlt">C</span>]beta-carotene. Other organs also contained [<span class="hlt">14</span><span class="hlt">C</span>]beta-carotene, confirming the ability of the monkey to absorb intact beta-carotene. In addition, monkey livers and other organs were found to contain lutein, zeaxanthin, alpha-cryptoxanthin, beta-cryptoxanthin and beta-carotene, presumably arising from dietary sources. PMID:2303914</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24909078','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24909078"><span id="translatedtitle">Biosynthesis of steroidal alkaloids in Solanaceae plants: incorporation of 3β-hydroxycholest-5-en-<span class="hlt">26</span>-<span class="hlt">al</span> into tomatine with tomato seedlings.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ohyama, Kiyoshi; Okawa, Akiko; Fujimoto, Yoshinori</p> <p>2014-08-01</p> <p>The C-26 amino group of tomatine, a representative Solanaceae steroidal alkaloid, is introduced in an early step of its biosynthesis from cholesterol. We recently proposed a transamination mechanism for the C-26 amination as opposed to the previously proposed mechanism involving a nitrogen nucleophilic displacement. In the present study, a deuterium labeled C-26 aldehyde, (24,24,27,27,27-(2)H5)-3β-hydroxycholest-5-en-<span class="hlt">26</span>-<span class="hlt">al</span>, was synthesized and fed to a tomato (Solanum lycopersicum) seedling. LC-MS analysis of the biosynthesized tomatine indicated that the labeled aldehyde was incorporated into tomatine. The finding strongly supports the intermediacy of the aldehyde and the transamination mechanism during C-26 amination.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA.....9292C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA.....9292C"><span id="translatedtitle">B and Mg isotopic variations in Leoville mrs-06 type B1 cai:origin of 10Be and <span class="hlt">26</span><span class="hlt">Al</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chaussidon, M.; Robert, F.; Russel, S. S.; Gounelle, M.; Ash, R. D.</p> <p>2003-04-01</p> <p>The finding [1-3] in Ca-Al-rich refractory inclusions (CAI) of primitive chondrites of traces of the in situ decay of radioactive 10Be (half-life 1.5Myr) indicates that irradiation of the protosolar nebula by the young Sun in its T-Tauri phase has produced significant amounts of the Li-Be-B elements. This irradiation may have produced also some or all of the short-lived <span class="hlt">26</span><span class="hlt">Al</span> (half-life 0.7Myr) and 41Ca (half-life 0.1Myr) previously detected in CAIs. To constrain the origin of 10Be and 10Al it is important to look for coupled variations in the 10Be/9Be and <span class="hlt">26</span><span class="hlt">Al</span>/27Al ratios in CAIs and to understand the processes responsible for these variations (e.g. variations in the fluences of irradiation, secondary perturbations of the CAIs, ...) We have thus studied the Li and B isotopic compositions and the Be/Li and Be/B concentration ratios in one CAI (MRS-06) from the Leoville CV3 chondrite in which large variations of the Mg isotopic compositions showing both the in situ decay of <span class="hlt">26</span><span class="hlt">Al</span> and the secondary redistribution of Mg isotopes have been observed [4]. The results show large variations for the Li and B isotopic compositions (^7Li/^6Li ranging from 11.02±0.21 to 11.82±0.07, and 10B/11B ratios ranging from 0.2457±0.0053 to 0.2980±0.0085). The ^7Li/^6Li ratio tend to decrease towards the rim of the inclusion. The 10B/11B ratios are positively correlated with the ^9Be/11B ratios indicating the in situ decay of 10Be. However perturbations of the 10Be/B system are observed. They would correspond to an event which occurred approximately 2Myr after the formation of the CAI and the irradiation of the CAI precursors which is responsible for the 10Be observed in the core of the CAI. These perturbations seem compatible with those observed for the <span class="hlt">26</span><span class="hlt">Al</span>/Mg system but they might be due to an irradiation of the already-formed, isolated CAI which would have resulted in increased 10Be/^9Be ratios and low ^7Li/^6Li ratios in the margin of the CAI. [1] McKeegan K. D. et al. (2000</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/15001999','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/15001999"><span id="translatedtitle">The LLNL Accelerator Mass Spectrometry System for Biochemical <span class="hlt">14</span><span class="hlt">C</span>-Measurements</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ognibene, T J; Bench, G; Brown, T A; Vogel, J S</p> <p>2002-10-31</p> <p>We report on recent improvements made to our 1 MV accelerator mass spectrometry system that is dedicated to {sup <span class="hlt">14</span>}<span class="hlt">C</span> quantification of biochemical samples. Increased vacuum pumping capacity near the high voltage terminal has resulted in a 2-fold reduction of system backgrounds to 0.04 amol {sup <span class="hlt">14</span>}<span class="hlt">C</span>/mg carbon. Carbon ion transmission through the accelerator has also improved a few percent. We have also developed tritium measurement capability on this spectrometer. The {sup 3}H/{sup 1}H isotopic ratio of a milligram-sized processed tap water sample has been measured at 4 {+-} 1 x 10{sup -16} (430 {+-} 110 {micro}Bq/mg H). Measurement throughput for a typical biochemical {sup 3}H sample is estimated to be {approx}10 minutes/sample.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6038389','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6038389"><span id="translatedtitle">Behavior of sup <span class="hlt">14</span> <span class="hlt">C</span> aflatoxin M1 during camembert cheese making</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Fremy, J.M.; Roiland, J.C.; Gaymard, A. )</p> <p>1990-05-01</p> <p>Camembert cheeses are made from raw milk spiked with aflatoxin M1. Three aflatoxin M1 levels (7.5 micrograms/L, 3 micrograms/L, and 0.3 micrograms/L) are used. In curds 35.6, 47.1, and 57.7% of aflatoxin M1, respectively, are recovered, and in wheys 64.4, 52.9, and 42.3%, respectively, are recovered. During the first 15 days of storage, the aflatoxin M1 content of different cheeses decreases 25, 55, and 75%, respectively. A similar experiment is made with milk contaminated with {sup <span class="hlt">14</span>}<span class="hlt">C</span> labeled aflatoxin M1. The same results are obtained, except for the behavior of aflatoxin M1 in cheese; the same <span class="hlt">14</span><span class="hlt">C</span> activity is recovered during storage for 30 days.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70020892','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70020892"><span id="translatedtitle">Changes in<span class="hlt">14</span><span class="hlt">c</span> activity over time during vacuum distillation of carbon from rock pore water</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Davidson, G.R.; Yang, I.C.</p> <p>1999-01-01</p> <p>The radiocarbon activity of carbon collected by vacuum distillation from a single partially saturated tuff began to decline after approximately 60% of the water and carbon had been extracted. Disproportionate changes in <span class="hlt">14</span><span class="hlt">C</span> activity and ??13C during distillation rule out simple isotopic fractionation as a causative explanation. Additional phenomena such as matrix diffusion and ion exclusion in micropores may play a role in altering the isotopic value of extracted carbon, but neither can fully account for the observed changes. The most plausible explanation is that distillation recovers carbon from an adsorbed phase that is depleted in <span class="hlt">14</span><span class="hlt">C</span> relative to DIC in the bulk pore water. ?? 1999 by the Arizona Board of Regents on behalf of the University of Arizona.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.A32A..03L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.A32A..03L"><span id="translatedtitle">A low cost optical radiocarbon (<span class="hlt">14</span><span class="hlt">C</span>) sensor for greenhouse gas source attribution</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Long, D.; Fleisher, A. J.; Liu, Q.; Hodges, J. T.</p> <p>2015-12-01</p> <p>Radiocarbon (<span class="hlt">14</span><span class="hlt">C</span>) provides a convenient means for the attribution of atmospheric greenhouse gases between anthropogenic and biogenic sources. Unfortunately, routine measurements are costly and require extensive sample preparation to meet sensitivity goals only achievable at large accelerator mass spectrometer facilities. We describe an alternate approach in which a laser is used to selectively record the absorption signatures of the <span class="hlt">14</span><span class="hlt">C</span> isotope of CO2. The designed instrument will allow for bench-top measurements of 14CO2 at and below ambient levels (~1.2 parts-per-trillion). The use of a commercially available mid-infrared quantum cascade laser as the optical source greatly reduces the cost of the instrument over more complicated sources and should allow for routine inline measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10108530','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10108530"><span id="translatedtitle">{sup <span class="hlt">14</span>}<span class="hlt">C</span>-AMS quantification of biomolecular interactions using microbore and plate separations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Creek, M.R.; Frantz, C.E.; Fultz, E.; Haack, K.; Redwine, K.; Shen, N.; Turteltaub, K.W.; Vogel, J.S.</p> <p>1993-10-20</p> <p>AMS sensitivity arises from the direct counting of radioisotopes without interference from molecular isobars. No chemical or physical information other than a bulk isotope ratio is available from the usual AMS instrument. Chemical or biological significance of the isotope ratio depends on the definition of the sample prior to conversion to material used in the ion source. The authors use AMS to quantify biochemical interactions between labeled xenobiotics and their potential targets of toxicity. These potential target molecules are separated and defined by various types of plate and microbore separations, including thin layer chromatography (TLC), high performance liquid chromatography (HPLC) and gel electrophoresis (GE) in quantifying the binding of {sup <span class="hlt">14</span>}<span class="hlt">C</span>-labeled compounds to specific DNA and protein fragments. They discuss their methods of using these microbore and plate separations of biomolecules while controlling contamination from {sup <span class="hlt">14</span>}<span class="hlt">C</span> in laboratory equipment and give examples.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014MPLA...2950125D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014MPLA...2950125D"><span id="translatedtitle">Astrophysical S-factor of the radiative proton capture on <span class="hlt">14</span><span class="hlt">C</span> at low energies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dubovichenko, Sergey; Burtebaev, Nasurlla; Dzhazairov-Kakhramanov, Albert; Alimov, Dilshod</p> <p>2014-07-01</p> <p>The phase shift analysis for position location of the 2S1/2 resonance at 1.5 MeV was carried out on the basis of the known experimental measurements of the excitation functions of the p<span class="hlt">14</span><span class="hlt">C</span> elastic scattering at four angles from 90° to 165° and more than 100 energy values in the range from 600-800 keV to 2200-2400 keV. Also, the possibility to describe the available experimental data on the astrophysical S-factor for the proton capture reaction on <span class="hlt">14</span><span class="hlt">C</span> to the ground state (GS) of 15N at astrophysical energies was considered in the frame of modified potential cluster model (MPCM).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5098188','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5098188"><span id="translatedtitle">Detection of an azido-(/sup <span class="hlt">14</span>/<span class="hlt">C</span>)-atrazine labeled protein transferred to nitrocellulose paper</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ivey, S.; Metz, J.G.; Berg, S.P.</p> <p>1986-04-01</p> <p>An electrophoretically similar protein in spinach and maize can be covalently labeled with azido-(/sup <span class="hlt">14</span>/<span class="hlt">C</span>)-atrazine and separated by 10-18% gradient LDS-PAGE. The protein profile can be transferred to nitrocellulose paper (ncp) by western blotting. The ncp containing the protein profile is sliced into 2 mm slices and counted with liquid scintillation. The labeled protein migrates as a diffuse band with a Mr of 34 kD. This band migrates at a higher Mr (40 kD) under different gel conditions. The ncp dissolves in the organic scintillation cocktail thus providing a more sensitive and quantitative detection of the /sup <span class="hlt">14</span>/<span class="hlt">C</span>. This technique allows the simultaneous immunological and radiochemical identification of many electrophoretically separable proteins.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5561033','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5561033"><span id="translatedtitle">( sup <span class="hlt">14</span> <span class="hlt">C</span>)-Sucrose uptake by guard cell protoplasts of pisum sativum, argenteum mutant</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rohrig, K.; Raschke, K. )</p> <p>1991-05-01</p> <p>Guard cells rely on import for their supply with reduced carbon. The authors tested by silicone oil centrifugation the ability of guard cell protoplasts to accumulated ({sup <span class="hlt">14</span>}<span class="hlt">C</span>)-sucrose. Uptake rates were corrected after measurement of {sup <span class="hlt">14</span>}<span class="hlt">C</span>-sorbitol and {sup 3}H{sub 2}O spaces. Sucrose uptake followed biphasic kinetics, with a high-affinity component below 1 mM external sucrose (apparent K{sub m} 0.8 mM at 25C) and a low-affinity nonsaturable component above. Uptake depended on pH (optimum at pH 5.0). Variations in the concentrations of external KCl, CCCP, and valinomycin indicated that about one-half of the sucrose uptake rate could be related to an electrochemical gradient across the plasmalemma. Total uptake rates measured at 5 mM external sucrose seem to be sufficient to replenish emptied plastids with starch within a few hours.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=426143','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=426143"><span id="translatedtitle">Temperature and Oxygen Effects on <span class="hlt">14</span><span class="hlt">C</span>-Photosynthate Unloading and Accumulation in Developing Soybean Seeds</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Thorne, John H.</p> <p>1982-01-01</p> <p>The environmental sensitivity of the processes associated with the import of photosynthate by developing soybean seeds was investigated within intact fruit and with excised, immature embryos. Intact pods of field-grown (Glycine max [L.] Merr.) Amsoy 71 soybeans were subjected to localized regimes of 0, 21, or 100% O2 and 15, 25, or 35°C during pulsechase translocation experiments and, 2.5 hours later, the uptake and distribution of <span class="hlt">14</span><span class="hlt">C</span>-photosynthate among dissected fruit tissues determined. In other experiments, excised embryos were incubated in [<span class="hlt">14</span><span class="hlt">C</span>]sucrose solutions under various experimental conditions to separate the effects of these treatments on accumulation by the embryos from those which may operate on phloem unloading in the maternal seedcoat. Import of <span class="hlt">14</span><span class="hlt">C</span>-photosynthate by intact soybean fruit was both temperature- and O2-dependent. This dependency was shown to occur only within the seeds; import by the pod walls was essentially insensitive to fruit temperature or O2 treatments. The embryos of anaerobic fruit were completely unlabeled, regardless of fruit temperature. But under anaerobic in vitro incubation conditions, uptake of [<span class="hlt">14</span><span class="hlt">C</span>]sucrose in excised embryos was only 30% less than that in aerobic in vitro conditions. The data suggest that, within intact fruit, anoxia prevented sucrose efflux from the seed coat phloem and any subsequent uptake by the embryo. The demonstrated energy dependence of phloem unloading may reflect requirements for membrane integrity or energy metabolism in the companion cell-sieve element complex, consistent with a facilitated unloading process. Collectively, these data characterize the environmental sensitivity of photosynthate import in developing soybean fruit. They imply that environmental regulation of import may occur at both the embryo level and at the phloem terminals within the seed coat. PMID:16662182</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6137966','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6137966"><span id="translatedtitle">Goldenrod ball gall effects on Solidago altissima: /sup <span class="hlt">14</span>/<span class="hlt">C</span> translocation and growth. [Eurosta solidaginis</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>McCrea, K.D.; Abrahamson, W.G.; Weis, A.E.</p> <p>1985-12-01</p> <p>Individual leaves of S. altissima were labeled with carbon-14 introduced as CO/sub 2/. The /sup <span class="hlt">14</span>/<span class="hlt">C</span> was introduced into ramets that had ball galls caused by the fly Eurosta solidaginis and into ungalled control ramets; gall size (large vs. small) and point of introduction of the label (above vs. below the gall) were experimental factors. After 5 d the ramets were harvested and their component organs were assayed for /sup <span class="hlt">14</span>/<span class="hlt">C</span> using liquid scintillation. In addition, a field cohort of 359 galled and ungalled ramets was followed during the period of gall growth to determine the effect of the gall on stem height growth. Gall size and labeling position had no effect on the percent of /sup <span class="hlt">14</span>/<span class="hlt">C</span> translocated out of the labeled leaf but did affect the distribution of translocated /sup <span class="hlt">14</span>/<span class="hlt">C</span>. Translocation to underground organs was reduced when the label was introduced above the gall, the reduction being related to gall size. Large galls reduced translocation to the apical bud when the label was introduced below the gall, but small galls did not. Translocation to underground organs was not affected by the gall when the label was introduced below the gall and translocation to the apical bud was not affected by the gall when the label was introduced above the gall; these results indicate that the goldenrod ball gall is a nonmobilizing gall. The presence of a gall did not significantly affect final stem height but did slow the growth of ramets during the period of most rapid gall growth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3726336','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3726336"><span id="translatedtitle">Product inhibition of cellulases studied with <span class="hlt">14</span><span class="hlt">C</span>-labeled cellulose substrates</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2013-01-01</p> <p>Background As a green alternative for the production of transportation fuels, the enzymatic hydrolysis of lignocellulose and subsequent fermentation to ethanol are being intensively researched. To be economically feasible, the hydrolysis of lignocellulose must be conducted at a high concentration of solids, which results in high concentrations of hydrolysis end-products, cellobiose and glucose, making the relief of product inhibition of cellulases a major challenge in the process. However, little quantitative information on the product inhibition of individual cellulases acting on cellulose substrates is available because it is experimentally difficult to assess the hydrolysis of the heterogeneous polymeric substrate in the high background of added products. Results The cellobiose and glucose inhibition of thermostable cellulases from Acremonium thermophilum, Thermoascus aurantiacus, and Chaetomium thermophilum acting on uniformly <span class="hlt">14</span><span class="hlt">C</span>-labeled bacterial cellulose and its derivatives, <span class="hlt">14</span><span class="hlt">C</span>-bacterial microcrystalline cellulose and <span class="hlt">14</span><span class="hlt">C</span>-amorphous cellulose, was studied. Cellulases from Trichoderma reesei were used for comparison. The enzymes most sensitive to cellobiose inhibition were glycoside hydrolase (GH) family 7 cellobiohydrolases (CBHs), followed by family 6 CBHs and endoglucanases (EGs). The strength of glucose inhibition followed the same order. The product inhibition of all enzymes was relieved at higher temperatures. The inhibition strength measured for GH7 CBHs with low molecular-weight model substrates did not correlate with that measured with <span class="hlt">14</span><span class="hlt">C</span>-cellulose substrates. Conclusions GH7 CBHs are the primary targets for product inhibition of the synergistic hydrolysis of cellulose. The inhibition must be studied on cellulose substrates instead of on low molecular-weight model substrates when selecting enzymes for lignocellulose hydrolysis. The advantages of using higher temperatures are an increase in the catalytic efficiency of enzymes and the relief of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5799124','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5799124"><span id="translatedtitle">Release of ( sup <span class="hlt">14</span> <span class="hlt">C</span>)5-hydroxytryptamine from human platelets by red wine</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jarman, J.; Glover, V.; Sandler, M. )</p> <p>1991-01-01</p> <p>Red wine, at a final dilution of 1/50, caused released of ({sup <span class="hlt">14</span>}<span class="hlt">C</span>)5-hydroxytryptamine (5-HT) from preloaded platelets, an effect which was not observed with any white wines or beers tested. Since 5-HT, is probably released from body stores during migraine attacks and red wine is known to provoke migraine episodes in susceptible individuals, release of 5-HT, possibly from central stores, could represent a plausible mechanism for its mode of action.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5857944','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5857944"><span id="translatedtitle">Incorporation of UDP-( sup <span class="hlt">14</span> <span class="hlt">C</span>)glucose into xyloglucan by pea membranes</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gordon, R.; Maclachlan, G. )</p> <p>1989-09-01</p> <p>The water-insoluble 1,4-{beta}-linked products formed from UDP-({sup <span class="hlt">14</span>}<span class="hlt">C</span>)glucose by pea membranes were dissolved in hot dimethylsulfoxide/paraformaldehyde and fractionated on columns of controlled pore glass beads calibrated with dextran standards. The products eluted with a peak size close to 70 kilodaltons in dextran equivalents. Similar elution profiles were obtained for products formed in brief or extended incubations and at high or low substrate concentrations. Methylation analysis indicated that only a few ({sup <span class="hlt">14</span>}<span class="hlt">C</span>)glucose units had been added to an endogenous acceptor to form this product. In the presence of UDP-xylose at concentrations equal to or less than UDP-({sup <span class="hlt">14</span>}<span class="hlt">C</span>)glucose, incorporation from the latter was enhanced and the products elongated with time to a size range where the major components eluted between dextran 264 and 500 kilodaltons. Treatment with endo-1,4-{beta}-glucanase resulted in a mixture of oligosaccharides, including the xyloglucan subunit Glc{sub 4}Xyl{sub 3}, which were hydrolyzed further by mixed glycosidases to labeled glucose and isoprimeverose (xylosyl-1,6-{alpha}-D-glucose). In pulse-chase experiments, low molecular weight product formed from UDP-({sup <span class="hlt">14</span>}<span class="hlt">C</span>)glucose alone was clearly a precursor for high molecular weight products formed subsequently in the presence of both UDP-glucose and UDP-xylose. It is concluded that the 1,4-{beta}-transglucosylation activity detected in these tests was due to an enzyme that is required for biosynthesis of the backbone of xyloglucan.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7188081','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7188081"><span id="translatedtitle">Kernel abortion in maize. II. Distribution of /sup <span class="hlt">14</span>/<span class="hlt">C</span> among kernel carboydrates</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hanft, J.M.; Jones, R.J.</p> <p>1986-06-01</p> <p>This study was designed to compare the uptake and distribution of /sup <span class="hlt">14</span>/<span class="hlt">C</span> among fructose, glucose, sucrose, and starch in the cob, pedicel, and endosperm tissues of maize (Zea mays L.) kernels induced to abort by high temperature with those that develop normally. Kernels cultured in vitro at 309 and 35/sup 0/C were transferred to (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)sucrose media 10 days after pollination. Kernels cultured at 35/sup 0/C aborted prior to the onset of linear dry matter accumulation. Significant uptake into the cob, pedicel, and endosperm of radioactivity associated with the soluble and starch fractions of the tissues was detected after 24 hours in culture on atlageled media. After 8 days in culture on (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)sucrose media, 48 and 40% of the radioactivity associated with the cob carbohydrates was found in the reducing sugars at 30 and 35/sup 0/C, respectively. Of the total carbohydrates, a higher percentage of label was associated with sucrose and lower percentage with fructose and glucose in pedicel tissue of kernels cultured at 35/sup 0/C compared to kernels cultured at 30/sup 0/C. These results indicate that sucrose was not cleaved to fructose and glucose as rapidly during the unloading process in the pedicel of kernels induced to abort by high temperature. Kernels cultured at 35/sup 0/C had a much lower proportion of label associated with endosperm starch (29%) than did kernels cultured at 30/sup 0/C (89%). Kernels cultured at 35/sup 0/C had a correspondingly higher proportion of /sup <span class="hlt">14</span>/<span class="hlt">C</span> in endosperm fructose, glucose, and sucrose.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5639496','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5639496"><span id="translatedtitle">In vitro uptake of /sup <span class="hlt">14</span>/<span class="hlt">C</span>-praziquantel by cestodes, trematodes, and a nematode</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Andrews, P.; Thomas, H.; Weber, H.</p> <p>1980-12-01</p> <p>/sup <span class="hlt">14</span>/<span class="hlt">C</span>-praziquantel was rapidly taken up by Schistosoma mansoni, Fasciola hepatica, Hymenolepis nana, and isolated strobilocerci of Taenia taeniaeformis. Schistosoma mansoni lost praziquantel rapidly to drug-free medium. Chromatography of extracts prepared after incubation of S. mansoni and H. nana yielded no indication that praziquantel was metabolized. Autoradiography revealed a uniform distribution of praziquantel throughout the tissues of S. mansoni and H. nana. Uptake was considerably slower in the nematode Heterakis spumosa and apparently via the oral route.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1062002','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1062002"><span id="translatedtitle">Incorporation of UDP-[<span class="hlt">14</span><span class="hlt">C</span>]Glucose into Xyloglucan by Pea Membranes 1</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Gordon, Ruth; Maclachlan, Gordon</p> <p>1989-01-01</p> <p>The water-insoluble 1,4-β-linked products formed from UDP-[<span class="hlt">14</span><span class="hlt">C</span>]glucose by pea membranes were dissolved in hot dimethyl-sulfoxide/paraformaldehyde and fractionated on columns of controlled pore glass beads calibrated with dextran standards. The products eluted with a peak size close to 70 kilodaltons in dextran equivalents. Similar elution profiles were obtained for products formed in brief or extended incubations and at high or low substrate concentrations. Methylation analysis indicated that only a few [<span class="hlt">14</span><span class="hlt">C</span>]glucose units had been added to an endogenous acceptor to form this product. In the presence of UDP-xylose at concentrations equal to or less than UDP-[<span class="hlt">14</span><span class="hlt">C</span>]glucose, incorporation from the latter was enhanced and the products elongated with time to a size range where the major components eluted between dextran 264 and 500 kilodaltons. Treatment with endo-1,4-β-glucanase resulted in a mixture of oligosaccharides, including the xyloglucan subunit Glc4Xyl3, which were hydrolyzed further by mixed glycosidases to labeled glucose and isoprimeverose (xylosyl-1,6-α-d-glucose). In pulse-chase experiments, the low molecular weight product formed from UDP-[<span class="hlt">14</span><span class="hlt">C</span>]glucose alone was clearly a precursor for high molecular weight products formed subsequently in the presence of both UDP-glucose and UDP-xylose. It is concluded that the 1,4-β-transglucosylation activity detected in these tests was due to an enzyme that is required for biosynthesis of the backbone of xyloglucan. Images Figure 2 PMID:16667028</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5966624','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5966624"><span id="translatedtitle">Theoretical estimates of the rates of radioactive decay of radium isotopes by /sup <span class="hlt">14</span>/<span class="hlt">C</span> emission</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Shi, Y.; Swiatecki, W.J.</p> <p>1985-01-28</p> <p>The measured branching ratios for the decays of /sup 222,223,224/Ra by alpha or /sup <span class="hlt">14</span>/<span class="hlt">C</span> emissions can be accounted for within a factor of 10 in terms of the ratios of Gamow penetrabilities through potential-energy barriers consisting of a Coulomb repulsion, the nuclear proximity attraction, and an interpolation between the configuration of tangent fragments and the configuration of the parent nucleus.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014HESS...18.4951A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014HESS...18.4951A"><span id="translatedtitle">Using <span class="hlt">14</span><span class="hlt">C</span> and 3H to understand groundwater flow and recharge in an aquifer window</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Atkinson, A. P.; Cartwright, I.; Gilfedder, B. S.; Cendón, D. I.; Unland, N. P.; Hofmann, H.</p> <p>2014-12-01</p> <p>Knowledge of groundwater residence times and recharge locations is vital to the sustainable management of groundwater resources. Here we investigate groundwater residence times and patterns of recharge in the Gellibrand Valley, southeast Australia, where outcropping aquifer sediments of the Eastern View Formation form an "aquifer window" that may receive diffuse recharge from rainfall and recharge from the Gellibrand River. To determine recharge patterns and groundwater flow paths, environmental isotopes (3H, <span class="hlt">14</span><span class="hlt">C</span>, δ13C, δ18O, δ2H) are used in conjunction with groundwater geochemistry and continuous monitoring of groundwater elevation and electrical conductivity. The water table fluctuates by 0.9 to 3.7 m annually, implying recharge rates of 90 and 372 mm yr-1. However, residence times of shallow (11 to 29 m) groundwater determined by <span class="hlt">14</span><span class="hlt">C</span> are between 100 and 10 000 years, 3H activities are negligible in most of the groundwater, and groundwater electrical conductivity remains constant over the period of study. Deeper groundwater with older <span class="hlt">14</span><span class="hlt">C</span> ages has lower δ18O values than younger, shallower groundwater, which is consistent with it being derived from greater altitudes. The combined geochemistry data indicate that local recharge from precipitation within the valley occurs through the aquifer window, however much of the groundwater in the Gellibrand Valley predominantly originates from the regional recharge zone, the Barongarook High. The Gellibrand Valley is a regional discharge zone with upward head gradients that limits local recharge to the upper 10 m of the aquifer. Additionally, the groundwater head gradients adjacent to the Gellibrand River are generally upwards, implying that it does not recharge the surrounding groundwater and has limited bank storage. <span class="hlt">14</span><span class="hlt">C</span> ages and Cl concentrations are well correlated and Cl concentrations may be used to provide a first-order estimate of groundwater residence times. Progressively lower chloride concentrations from 10</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/6546684','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/6546684"><span id="translatedtitle">Biosynthesis of riboflavin. Enzymatic formation of the xylene moiety from [<span class="hlt">14</span><span class="hlt">C</span>]ribulose 5-phosphate.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nielsen, P; Neuberger, G; Floss, H G; Bacher, A</p> <p>1984-02-14</p> <p>We have studied the enzymatic formation of the xylene ring of riboflavin using cell extracts from the flavinogenic yeast Candida guilliermondii. 5-Amino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione or its 5'-phosphate could serve as substrates. In addition, a pentose phosphate or pentulose phosphate was required. Experiments with [<span class="hlt">14</span><span class="hlt">C</span>]ribulose 5-phosphate gave evidence for the incorporation of the ribulose carbon atoms except C-4 into the xylene ring of the vitamin. PMID:6546684</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21431117','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21431117"><span id="translatedtitle">A New {sup <span class="hlt">14</span>}<span class="hlt">C</span>-AMS Facility at UFF- Niteroi, Brazil</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gomes, P. R. S.; Macario, K. D.; Anjos, R. M.; Linares, R.; Carvalho, C.; Queiroz, E.</p> <p>2010-08-04</p> <p>We report a new Accelerator Mass Spectrometry facility at the Physics Institute of Fluminense Federal University in Brazil, the Nuclear Chronology Laboratory - LACRON. The sample preparation laboratory is ready to perform chemical treatment through graphitization and the acquisition of a Single Stage Accelerator Mass Spectrometry System is in progress. LACRON will be the first independent laboratory to perform the {sup <span class="hlt">14</span>}<span class="hlt">C</span>-AMS technique not only in Brazil but in Latin America.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/220894','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/220894"><span id="translatedtitle">Polymorphism of <span class="hlt">14</span><span class="hlt">C</span> vitamin D3 binding protein in cattle and water buffalo serum.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Masina, P; Ramunno, L; Iannelli, D</p> <p>1978-01-01</p> <p>Cattle and water buffalo sera labelled with vitamin D3[<span class="hlt">14</span><span class="hlt">C</span>] (300 and 480 individual samples respectively) were subjected to starch gel electrophoresis followed by autoradiography in an attempt to identify a possible polymorphism of the proteins capable of binding this vitamin. Three phenotypes controlled by two codominant autosomal alleles were identified in cattle while in water buffalo six phenotypes controlled by three codominant autosomal alleles were observed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5551986','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5551986"><span id="translatedtitle">In vitro covalent binding of 3-(/sup <span class="hlt">14</span>/<span class="hlt">C</span>)methylindole metabolites in goat tissues</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bray, T.M.; Carlson, J.R.; Nocerini, M.R.</p> <p>1984-05-01</p> <p>Covalent binding of 3-(/sup <span class="hlt">14</span>/<span class="hlt">C</span>)methylindole (3(/sup <span class="hlt">14</span>/<span class="hlt">C</span>)MI) in crude microsomal preparations of goat lung, liver, and kidney was measured to determine if a reactive intermediate was formed during the in vitro metabolism of 3-methylindole (3MI). The bound radioactivity was highest in lung compared to liver and kidney. The amount of bound radioactivity per nanomole of cytochrome P-450 was approximately 10 times higher in the lung compared to the liver. No detectable bound radioactivity was found when 3-(/sup 3/H)methyloxindole was used as the substrate. Cofactor requirements and the effects of inhibitors indicate that a mixed function oxidase (MFO) system is involved in formation of a reactive intermediate. Inhibitors and conjugating agents that are known to reduce the severity of 3MI-induced lung injury such as piperonyl butoxide (MFO inhibitor) and glutathione (conjugating agent) significantly decreased the in vitro binding of 3(/sup <span class="hlt">14</span>/<span class="hlt">C</span>)MI. The results indicate that a reactive intermediate is produced during the metabolism of 3MI by the MFO system. The organ specificity in binding suggests that covalent binding by lung microsomes may be related to the mechanism of 3MI-induced lung injury.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013NIMPB.294..266N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013NIMPB.294..266N"><span id="translatedtitle">An approach toward automatic graphitization of CO2 samples for AMS <span class="hlt">14</span><span class="hlt">C</span> measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nagasawa, Shigenobu; Kitagawa, Hiroyuki; Nakanishi, Toshimichi; Tanabe, Susumu; Hong, Wan</p> <p>2013-01-01</p> <p>To improve the throughput of sample preparation for AMS <span class="hlt">14</span><span class="hlt">C</span> measurements, we made improvements to a manually operated system for CO2 reduction at the Graduate School of Environmental Studies, Nagoya University. Most of the processes of the CO2 reduction procedure were automated, and a CO2 sample containing 0.3-1 mg carbon was credibly reduced to graphite within a few hours by hydrogen gas with catalytic iron powder in a 7.4 ml reactor consisting of a quartz reduction tube, a pressure transducer gauge and a cold finger trap equipped with a temperature-controllable trap device for trapping CO2 and H2O. The improved system has the potential to easily carry out graphitization of more than 100 CO2 samples per week. The <span class="hlt">14</span><span class="hlt">C</span> values of graphite produced from <span class="hlt">14</span><span class="hlt">C</span>-free CO2 (>0.3 mg C) were 0.0028 ± 0.0010 fraction modern carbon (FMC) on average (n = 8, 1std), which are almost the same as the black level of 1-MV HVEE Tandetron installed at the Korea Institute of Geoscience and Mineral Resources (KIGAM).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1176674','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1176674"><span id="translatedtitle">Incorporation of l-[<span class="hlt">14</span><span class="hlt">C</span>]leucine into egg proteins by liver slices from cod</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Plack, P. A.; Fraser, N. W.</p> <p>1971-01-01</p> <p>1. Liver slices from cod (Gadus morhua L.) were incubated with l-[<span class="hlt">14</span><span class="hlt">C</span>]leucine and the incorporation of label into total protein, precipitated with trichloroacetic acid, and into egg proteins, precipitated with an antibody after addition of carrier egg proteins, was measured. 2. Liver slices from immature male or female cod, and from male fish with developing testes, did not incorporate significant amounts of l-[<span class="hlt">14</span><span class="hlt">C</span>]leucine into egg proteins, whereas with slices from female cod with developing ovaries the rate of incorporation into egg proteins was 8% of the rate of incorporation into total protein. 3. Liver slices from immature male or female fish that had received an intramuscular injection of oestradiol benzoate (1mg/kg) 5–8 days previously incorporated l-[<span class="hlt">14</span><span class="hlt">C</span>]leucine into egg proteins at about 26% of the rate of incorporation into total protein. 4. Incorporation into total protein and into egg proteins was inhibited by puromycin, and 1.2 and 0.13μg of puromycin/mg of tissue protein, respectively, gave 50% inhibition. PMID:16742749</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26546766','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26546766"><span id="translatedtitle">Role of biotransformation, sorption and mineralization of (<span class="hlt">14</span>)<span class="hlt">C</span>-labelled sulfamethoxazole under different redox conditions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Alvarino, T; Nastold, P; Suarez, S; Omil, F; Corvini, P F X; Bouju, H</p> <p>2016-01-15</p> <p>(<span class="hlt">14</span>)<span class="hlt">C</span>-sulfamethoxazole biotransformation, sorption and mineralization was studied with heterotrophic and autotrophic biomass under aerobic and anoxic conditions, as well as with anaerobic biomass. The (<span class="hlt">14</span>)<span class="hlt">C</span>-radiolabelled residues distribution in the solid, liquid and gas phases was closely monitored along a total incubation time of 190 h. Biotransformation was the main removal mechanism, mineralization and sorption remaining below 5% in all the cases, although the presence of a carbon source exerted a positive effect on the mineralization rate by the aerobic heterotrophic bacteria. In fact, an influence of the type of primary substrate and the redox potential was observed in all cases on the biotransformation and mineralization rates, since an enhancement of the removal rate was observed when an external carbon source was used as a primary substrate under aerobic conditions, while a negligible effect was observed under nitrifying conditions. In the liquid phases collected from all assays, up to three additional peaks corresponding to (<span class="hlt">14</span>)<span class="hlt">C</span>-radiolabelled residues were detected. The highest concentration was observed under anaerobic conditions, where two radioactive metabolites were detected representing each around 15% of the total applied radioactivity after 180 h incubation. One of the metabolites detected under anoxic and anaerobic conditions, is probably resulting from ring cleavage of the isoxazole ring. PMID:26546766</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/8777311','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/8777311"><span id="translatedtitle">Microdose <span class="hlt">14</span><span class="hlt">C</span>-urea breath test in detection of Helicobacter pylori.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bielański, W; Konturek, S J; Dobrzańska, M J; Pytko-Polończyk, J; Sito, E; Marshall, B J</p> <p>1996-03-01</p> <p>Etiologic role for Helicobacter pylori (Hp) seems to be well established in gastric pathology. The high urease activity of Hp can be used to detect this bacterium by non-invasive urea breath tests (UBT). We validated the microdose version of the test in which 37 kBq <span class="hlt">14</span><span class="hlt">C</span>-urea is given orally in capsule. With the cut off value > 100 DPM as positive, UBT results correlated highly significant with combined results for invasive methods i.e. CLOtest + histology score. The reproducibility of the test was 100%. The results obtained for the breath test performed locally were almost identical with that read at remote laboratory. The data found for fasting and fed states of subjects agreed in 87%. When <span class="hlt">14</span><span class="hlt">C</span>-urea was confined in the mouth of both Hp positive and Hp negative patients UBT showed the presence of urease activity in the mouth cavity. <span class="hlt">14</span><span class="hlt">C</span>-urea capsule based breath test is highly reliable, safe, and reproducible for detection of Hp in the stomach. Results can be obtained within 15 min if a scintilation counter is nearby, or breath samples can be mailed to a testing laboratory for analysis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23493903','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23493903"><span id="translatedtitle">The fate of dermally applied [<span class="hlt">14</span><span class="hlt">C</span>]d-limonene in rats and humans.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Api, Anne Marie; Ritacco, Gretchen; Hawkins, David R</p> <p>2013-01-01</p> <p>The fate of dermally applied [(<span class="hlt">14</span>)<span class="hlt">C</span>]d-limonene was evaluated in humans and Long-Evans rats. In rats, 5 mg/kg body weight of [(<span class="hlt">14</span>)<span class="hlt">C</span>]d-limonene applied dermally to the shaved back under occlusion, resulted in the absorption of approximately 12% of the dose. The absorbed d-limonene was completely metabolized and excreted rapidly, primarily from the urine (80%) with a small fraction (20%) excreted in the feces. There was no long-term retention of the test material in body tissues. In humans, following dermal application of 12 mg of [(<span class="hlt">14</span>)<span class="hlt">C</span>]d-limonene in ethanol (1 mL) to the back under nonocclusive conditions (for 1 h after application to allow the material to dry, thereafter under occlusion), only 0.16% of the dose was absorbed and the radioactivity was recovered from the urine. Radioactivity in human feces was below the limit of detection. These results indicate that under conditions of simulated use of fragrances and cosmetics, d-limonene has a low potential for dermal absorption and tissue accumulation, and the d-limonene that is absorbed is rapidly excreted in the urine. Based upon these findings and the knowledge that d-limonene possesses a low-systemic toxicity profile, it is reasonable to conclude that dermal exposure to d-limonene from fragrance and cosmetic applications is highly unlikely to result in any clinically significant human toxicity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997NIMPB.123..159M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997NIMPB.123..159M"><span id="translatedtitle">A compact <span class="hlt">14</span><span class="hlt">C</span> Isotope Ratio Mass Spectrometer for biomedical applications</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mous, D. J. W.; Purser, K. H.; Fokker, W.; van den Broek, R.; Koopmans, R. B.</p> <p>1997-03-01</p> <p>During the last two decades the unparalleled sensitivity of accelerator mass spectrometry (AMS) has allowed major developments in many areas of geoscience and archeology. It is projected that in the near future a similar potential for AMS expansion is likely in the field of biomedical research leading, ultimately, to clinical applications. As an example of the growth of this new field, at the Lawrence Livermore National Laboratory Center for AMS the number of biomedical <span class="hlt">14</span><span class="hlt">C</span> measurements already represents a significant fraction of the total for all <span class="hlt">14</span><span class="hlt">C</span>. Widespread adoption of AMS in the biomedical field does require, however, the availability of instruments that are small in comparison with existing AMS systems and that will operate in a manner that is simple and user-friendly. To meet this demand, High Voltage Engineering Europa (HVEE) has developed a miniature, high-efficiency AMS instrument designed to provide for biomedical samples {<span class="hlt">14</span><span class="hlt">C</span>}/{12C} ratios with an accuracy better than 2% and with backgrounds limitations below 0.1 Modern. The current status of this program will be presented in the present paper.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/14456','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/14456"><span id="translatedtitle">Tips and traps in the <span class="hlt">14</span><span class="hlt">C</span> Bio-AMS preparation laboratory (WSam 7)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Buchholz, B A; Haack, K W; Stewart, P H; Vogel, J S</p> <p>1999-10-12</p> <p>Maintaining a contamination free sample preparation lab for biological <span class="hlt">14</span> <span class="hlt">C</span> AMS requires the same or more diligence as a radiocarbon dating prep lab. Isotope ratios of materials routinely range over 4-8 orders of magnitude in a single experiment, dosing solutions contain thousands of DPM and gels used to separate proteins possess <span class="hlt">14</span> <span class="hlt">C</span> ratios of 1pMC. Radiocarbon contamination is a legacy of earlier tracer work in most biological laboratories, even if they were never hot labs. Removable surface contamination can be found and monitored using swipes. Contamination can be found on any surface routinely touched: door knobs, light switches, drawer handles, water faucets. In general, all surfaces routinely touched need to be covered with paper, foil, or plastic that can be changed frequently. Shared air supplies can also present problems by distributing hot aerosols throughout a building. Aerosols can be monitored for <span class="hlt">14</span> <span class="hlt">C</span> content using graphitized coal or fullerene soot mixed with metal powder as an absorber. The monitors can be set out in work spaces for 1-2 weeks and measured by AMS with regular samples. Frequent air changes help minimize aerosol contamination in many cases. Cross contamination of samples can be minimized by using disposable plastic or glassware in the prep lab, isolating samples from the air when possible and using positive displacement pipetters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70022282','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70022282"><span id="translatedtitle">Pollen-based biomes for Beringia 18,000, 6000 and 0 <span class="hlt">14</span><span class="hlt">C</span> yr BP</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Edwards, M.E.; Anderson, P.M.; Brubaker, L.B.; Ager, T.A.; Andreev, A.A.; Bigelow, N.H.; Cwynar, L.C.; Eisner, Wendy R.; Harrison, S.P.; Hu, F.-S.; Jolly, D.; Lozhkin, A.V.; MacDonald, G.M.; Mock, C.J.; Ritchie, J.C.; Sher, A.V.; Spear, R.W.; Williams, J.W.; Yu, G.</p> <p>2000-01-01</p> <p>The objective biomization method developed by Prentice et al. (1996) for Europe was extended using modern pollen samples from Beringia and then applied to fossil pollen data to reconstruct palaeovegetation patterns at 6000 and 18,000 <span class="hlt">14</span><span class="hlt">C</span> yr BP. The predicted modern distribution of tundra, taiga and cool conifer forests in Alaska and north-western Canada generally corresponds well to actual vegetation patterns, although sites in regions characterized today by a mosaic of forest and tundra vegetation tend to be preferentially assigned to tundra. Siberian larch forests are delimited less well, probably due to the extreme under-representation of Larix in pollen spectra. The biome distribution across Beringia at 6000 <span class="hlt">14</span><span class="hlt">C</span> yr BP was broadly similar to today, with little change in the northern forest limit, except for a possible northward-advance in the Mackenzie delta region. The western forest limit in Alaska was probably east of its modern position. At 18,000 <span class="hlt">14</span><span class="hlt">C</span> yr BP the whole of Beringia was covered by tundra. However, the importance of the various plant functional types varied from site to site, supporting the idea that the vegetation cover was a mosaic of different tundra types.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25277257','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25277257"><span id="translatedtitle">The impact of biochar on the bioaccessibility of (<span class="hlt">14</span>)<span class="hlt">C</span>-phenanthrene in aged soil.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ogbonnaya, O U; Adebisi, O O; Semple, K T</p> <p>2014-11-01</p> <p>Biochar is a carbon rich product from the incomplete combustion of biomass and it has been shown to reduce bioavailability of organic contaminants through adsorption. This study investigated the influence of 0%, 1%, 5% and 10% of two different particle sized wood biochars (≤2 mm and 3-7 mm) on the bioaccessibility of (<span class="hlt">14</span>)<span class="hlt">C</span>-phenanthrene (10 mg kg(-1)) in aged soil. The extent of (<span class="hlt">14</span>)<span class="hlt">C</span>-phenanthrene mineralisation by phenanthrene-degrading Pseudomonas sp. inoculum was monitored over a 14 day period in respirometric assays and compared to hydroxypropyl-β-cyclodextrin (HPCD) aqueous extraction. Notably, biochar amendments showed significant reduction in extents of mineralisation and HPCD extraction. Linear correlations between HPCD extractability and the total amount mineralised revealed good correlations, with 2 mm biochar showing a best fit (r(2) = 0.97, slope = 1.11, intercept = 1.72). Biochar reduced HPCD extractability and bioaccessibility of (<span class="hlt">14</span>)<span class="hlt">C</span>-phenanthrene to microorganisms in a similar manner. Biochar can aid risk reduction to phenanthrene exposure to biota in soil and HPCD can serve as a useful tool to assess the extent of exposure in biochar-amended soils.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5450915','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5450915"><span id="translatedtitle">Na/sup +/-dependent transport of /sup <span class="hlt">14</span>/<span class="hlt">C</span>-L-lysine across bullfrog alveolar epithelium</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kim, K.J.; Crandall, E.D.</p> <p>1986-03-01</p> <p>Transepithelial transport of the basic amino acid L-lysine has been studied utilizing the isolated intact bullfrog lung mounted in the Ussing chamber. Lungs were excised from doubly pithed bullfrogs and sandwiched between two hemichambers. /sup <span class="hlt">14</span>/<span class="hlt">C</span>-(U)-L-lysine was added to the upstream reservoir of amphibian Ringer solution, while the tissue was short-circuited. Two lungs from the same animal were used simultaneously to determine the two opposite unidirectional fluxes. Downstream and upstream radioactivities were assayed and used to estimate the apparent permeability (P) of the labeled lysine. Results indicate that the apparent P of /sup <span class="hlt">14</span>/<span class="hlt">C</span>-L-lysine measured in the alveolar (M) to the pleural (S) direction is 19.06 (+- 2.84) x 10/sup -7/ cm/s and P in the S to M direction is 3.29 (+- 0.02) x 10/sup -7/ cm/s. When the 100 mM NaCl in the bath was replaced by 110 mM choline chloride, the flux of /sup <span class="hlt">14</span>/<span class="hlt">C</span>-L-lysine from the alveolar to the pleural side decreased to the same value as that in the opposite direction. The flux from the pleural to the alveolar direction in the absence of Na/sup +/ did not change. These results suggest that the alveolar epithelium exhibits Na/sup +/-dependent amino acid (L-lysine) transport in the M->S, but not in the S->M, direction.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17592856','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17592856"><span id="translatedtitle">Soil metabolism of a new herbicide, [<span class="hlt">14</span><span class="hlt">C</span>]Pyribenzoxim, under flooded conditions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chang, Hee-Ra; Koo, Suk-Jin; Kim, Kyun; Ro, Hee-Myong; Moon, Joon-Kwan; Kim, Yong-Hwa; Kim, Jeong-Han</p> <p>2007-07-25</p> <p>To elucidate the fate of a new pyrimidinyloxybenzoic herbicide, pyribenzoxim, a soil metabolism study was carried out with [<span class="hlt">14</span><span class="hlt">C</span>]pyribenzoxim applied to a sandy loam soil under flooded conditions. The material balance of applied radioactivity ranged from 96.4 to 104.4% and from 96.1 to 101.9% for nonsterile and sterile soils, respectively. The half-life of [<span class="hlt">14</span><span class="hlt">C</span>]pyribenzoxim was calculated to be approximately 1.3 and 9.4 days for nonsterile and sterile soils, respectively. The metabolites identified during the study were 2,6-bis(4,6-dimethoxypyrimidin-2-yloxy)benzoic acid (M1) and 2-hydroxy-6-(4,6-dimethoxypyrimidin-2-yloxy)benzoic acid (M2), resulting from the cleavage of the ester bond and subsequent hydrolysis. The nonextractable radioactivity levels increased to 37.8% for nonsterile conditions at 50 days after treatment and to 38.2% for sterile conditions at 60 days after treatment. Fractionation of the nonextractable soil residues indicated that bound radioactivity was associated mainly with humin fraction. No significant volatile products or [<span class="hlt">14</span><span class="hlt">C</span>]carbon dioxide was observed during the study. On the basis of these results, pyribenzoxim is considered to undergo rapid degradation in soil by microbial and chemical reactions, mainly hydrolysis, which limits its transfer to and accumulation in lower soil layers and groundwater. Therefore, the possibility of environmental contamination from the use of pyribenzoxim is expected to be very low.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1813924A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1813924A"><span id="translatedtitle">The <span class="hlt">14</span><span class="hlt">C</span> age of glacial North Atlantic surface waters: Greenland Interstadial Events 2-13</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Austin, William; Hibbert, Fiona; Bard, Edouard; Bryant, Charlotte</p> <p>2016-04-01</p> <p>We present an updated compilation of surface ocean (Globigerina bulloides) AMS <span class="hlt">14</span><span class="hlt">C</span> ages for Greenland Interstadials (GI) 2-13, spanning the interval 25,000 - 45,000 cal BP from the mid-latitude NE Atlantic Ocean. New data from two marine sediment cores located 83 km apart in the NE Atlantic are presented: MD95-2006 (Barra Fan; 57°01.82 N, 10°03.48 W; 2120m water depth) and MD04-2822 (Rockall Trough; 56°50.54 N, 11°22.96 W; 2344m water depth) as well as published data from core MD95-2042 (Iberian Margin; 37°45'N, 10°10'W, 3146 m water depth). Replicated sea surface temperature (SST) records show evidence for abrupt warming events; we correlate these directly to the D/O cycles of the Greenland (NGRIP) ice-core oxygen isotope record. We test the proposed synchronization of two of these records using three geochemically distinct tephra isochrones (NAAZ-1, Fugloyarbanki and NAAZ-2). Our data provide a potentially useful new surface ocean composite record of <span class="hlt">14</span><span class="hlt">C</span> age from the mid-latitude North Atlantic, suggesting broadly consistent interstadial <span class="hlt">14</span><span class="hlt">C</span> age data from all three records; and highlight the advantage of tuning mid-latitude SST records to Greenland (tested with tephra isochrones where possible) when constructing marine age-models through this time interval.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5442380','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5442380"><span id="translatedtitle">Measurement of local cerebral blood flow with (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)iodoantipyrine in the mouse</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jay, T.M.; Lucignani, G.; Crane, A.M.; Jehle, J.; Sokoloff, L.</p> <p>1988-02-01</p> <p>Local cerebral blood flow was measured in the mouse by means of the (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)iodoantipyrine method. This method has been previously used in the monkey, dog, cat, and rat, but its application to small mammals such as the mouse requires special attention to potential sources of error. The small size of the mouse brain requires special attention to the rapid removal and freezing of the brain to minimize effects of postmortem diffusion of tracer in the tissue. Because of the relatively low diameter/length ratios of the catheters needed for arterial sampling in small animals, substantial errors can occur in the determination of the time course of the (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)iodoantipyrine concentration in the arterial blood unless corrections for lag time and dead space washout in the catheter are properly applied. Local cerebral blood flow was measured in seven awake mice with appropriate care to minimize these sources of error. The values were found to vary from 48 ml/100 g/min in the corpus callosum to 198 ml/100 g/min in the inferior colliculus. The results demonstrate that the (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)iodoantipyrine method can be used to measure local cerebral blood flow in the mouse and that the values in that species are, in general, somewhat higher than those in the rat.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/936963','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/936963"><span id="translatedtitle">Methods for high precision <span class="hlt">14</span><span class="hlt">C</span> AMS measurement of atmospheric CO2 at LLNL</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Graven, H D; Guilderson, T P; Keeling, R F</p> <p>2006-10-18</p> <p>Development of {sup <span class="hlt">14</span>}<span class="hlt">C</span> analysis with precision better than 2{per_thousand} has the potential to expand the utility of {sup 14}CO{sub 2} measurements for carbon cycle investigations as atmospheric gradients currently approach traditional measurement precision of 2-5{per_thousand}. The AMS facility at the Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, produces high and stable beam currents that enable efficient acquisition times for large numbers of {sup <span class="hlt">14</span>}<span class="hlt">C</span> counts. One million {sup <span class="hlt">14</span>}<span class="hlt">C</span> atoms can be detected in approximately 25 minutes, suggesting that near 1{per_thousand} counting precision is economically feasible at LLNL. The overall uncertainty in measured values is ultimately determined by the variation between measured ratios in several sputtering periods of the same sample and by the reproducibility of replicate samples. Experiments on the collection of one million counts on replicate samples of CO{sub 2} extracted from a whole air cylinder show a standard deviation of 1.7{per_thousand} in 36 samples measured over several wheels. This precision may be limited by the reproducibility of Oxalic Acid I standard samples, which is considerably poorer. We outline the procedures for high-precision sample handling and analysis that have enabled reproducibility in the cylinder extraction samples at the <2{per_thousand} level and describe future directions to continue increasing measurement precision at LLNL.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6749103','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6749103"><span id="translatedtitle">Urea recycling from the renal pelvis in sheep: A study with ( sup <span class="hlt">14</span> <span class="hlt">C</span>)urea</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Cirio, A.; Boivin, R. )</p> <p>1990-05-01</p> <p>To test the hypothesis that urea can be recycled from the renal pelvis, (<span class="hlt">14</span><span class="hlt">C</span>)urea diluted in native urine (1 microCi/ml) was perfused (0.5 ml/min) into one of the pelvises of sheep fed either normal (NP) or low (LP)-protein diets. Blood samples were obtained from the ipsilateral renal vein and from the carotid artery throughout the perfusions. <span class="hlt">14</span><span class="hlt">C</span> activity determinations in urine and plasma demonstrated a flux of (<span class="hlt">14</span><span class="hlt">C</span>)urea from the pelvis to renal vein blood (40,000 in NP and 130,000 disintegrations/min in LP sheep, P less than 0.01). The corresponding flux of native urea was only 1.5 times higher in NP than in LP sheep (6.8 +/- 1.1 vs. 4.7 +/- 2.9 mumol/min, not significant) despite their 8 times higher urinary concentration of urea. The fraction of filtered urea that was reabsorbed in the pelvis was larger in LP sheep (7.5 +/- 3.7 vs. 1.9 +/- 0.7% in NP sheep, P less than 0.05). A fraction of urea is thus actually recycled from the renal pelvis in sheep, and this pelvic retention is enhanced in LP animals. The importance of this phenomenon in the nitrogen economy is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7192806','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7192806"><span id="translatedtitle">sup <span class="hlt">14</span> <span class="hlt">C</span>-urea breath test for the detection of Helicobacter pylori</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Veldhuyzen van Zanten, S.J.; Tytgat, K.M.; Hollingsworth, J.; Jalali, S.; Rshid, F.A.; Bowen, B.M.; Goldie, J.; Goodacre, R.L.; Riddell, R.H.; Hunt, R.H. )</p> <p>1990-04-01</p> <p>The high urease activity of Helicobacter pylori can be used to detect this bacterium by noninvasive breath tests. We have developed a {sup <span class="hlt">14</span>}<span class="hlt">C</span>-urea breath test which uses 5 microCi {sup <span class="hlt">14</span>}<span class="hlt">C</span> with 50 mg nonradioactive urea. Breath samples are collected at baseline and every 30 min for 2 h. Our study compared the outcome of the breath test to the results of histology and culture of endoscopically obtained gastric biopsies in 84 patients. The breath test discriminated well between the 50 positive patients and the 34 patients negative for Helicobacter pylori: the calculated sensitivity was 100%, specificity 88%, positive predictive value 93%, and negative predictive value 100%. Treatment with bismuth subsalicylate and/or ampicillin resulted in lower counts of exhaled {sup 14}CO{sub 2} which correlated with histological improvement in gastritis. The {sup <span class="hlt">14</span>}<span class="hlt">C</span>-urea breath test is a better gold standard for the detection of Helicobacter pylori than histology and/or culture.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6698760','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6698760"><span id="translatedtitle">Characterization of nonexchangeable radioactivity in L1210 cells incubated with ( sup <span class="hlt">14</span> <span class="hlt">C</span>)thiotepa: Labeling of phosphatidylethanolamine</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Egorin, M.J.; Snyder, S.W. )</p> <p>1990-07-01</p> <p>N,N',N''-Triethylenethiophosphoramide ((<span class="hlt">14</span><span class="hlt">C</span>)thiotepa) accumulation by L1210 cells is a biphasic process. A very rapid initial phase is followed by a much slower second phase that reflects accumulation of radioactivity in a form that is not lost or exchanged when cells are resuspended and incubated in drug-free medium for up to 8 h. In this study we attempted to characterize this nonexchangeable radioactivity. Nuclei (10(7)) isolated from L1210 cells and incubated with (<span class="hlt">14</span><span class="hlt">C</span>)thiotepa did not accumulate <span class="hlt">14</span><span class="hlt">C</span> during incubations of up to 5 h. Similarly, nuclei isolated from 10(7) L1210 cells that had been shown to accumulate nonexchangeable <span class="hlt">14</span><span class="hlt">C</span> after incubation with (<span class="hlt">14</span><span class="hlt">C</span>)thiotepa did not show an increase in nuclear-associated <span class="hlt">14</span><span class="hlt">C</span>. Eighty to 85% of nonexchangeable <span class="hlt">14</span><span class="hlt">C</span> in L1210 cells incubated with (<span class="hlt">14</span><span class="hlt">C</span>)thiotepa was soluble in ethanol or chloroform:methanol (2:1, v/v), and although most of this cell-associated nonexchangeable <span class="hlt">14</span><span class="hlt">C</span> was precipitated by trichloroacetic acid, subsequent treatment of that precipitate with methanol solubilized most of the <span class="hlt">14</span><span class="hlt">C</span> so that only 15 to 20% remained with the final precipitate. When chloroform:methanol-soluble nonexchangeable <span class="hlt">14</span><span class="hlt">C</span> was analyzed with thin-layer chromatography systems suitable for thiotepa or simple lipids, all radioactivity remained at the origin. In contrast, when analyzed with one- and two-dimensional thin-layer chromatographic systems suitable for complex lipids, all chloroform:methanol-soluble radioactivity was associated with a single lipid spot. This lipid cochromatographed with phosphatidylethanolamine, reacted with ninhydrin but not with 4-(p-nitrobenzyl)pyridine or the Dragendorff choline reagent, and was digested by phospholipases C and D, all of which lead to its identification as phosphatidylethanolamine.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24028017','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24028017"><span id="translatedtitle">[Quantifying soil autotrophic microbes-assimilated carbon input into soil organic carbon pools following continuous <span class="hlt">14</span><span class="hlt">C</span> labeling].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shi, Ran; Chen, Xiao-Juan; Wu, Xiao-Hong; Jian, Yan; Yuan, Hong-Zhao; Ge, Ti-Da; Sui, Fang-Gong; Tong, Cheng-Li; Wu, Jin-Shui</p> <p>2013-07-01</p> <p>Soil autotrophic microbe has been found numerous and widespread. However, roles of microbial autotrophic processes and the mechanisms of that in the soil carbon sequestration remain poorly understood. Here, we used soils incubated for 110 days in a closed, continuously labeled <span class="hlt">14</span><span class="hlt">C</span>-CO2 atmosphere to measure the amount of labeled C incorporated into the microbial biomass. The allocation of <span class="hlt">14</span><span class="hlt">C</span>-labeled assimilated carbon in variable soil C pools such as dissolved organic C (DOC) and microbial biomass C (MBC) were also examined over the <span class="hlt">14</span><span class="hlt">C</span> labeling span. The results showed that significant amounts of <span class="hlt">14</span><span class="hlt">C</span>-SOC were measured in paddy soils, which ranged from 69.06-133.81 mg x kg(-1), accounting for 0.58% to 0.92% of the total soil organic carbon (SOC). The amounts of <span class="hlt">14</span><span class="hlt">C</span> in the dissolved organic C (<span class="hlt">14</span><span class="hlt">C</span>-DOC) and in the microbial biomass C (<span class="hlt">14</span><span class="hlt">C</span>-MBC) were dependent on the soils, ranged from 2.54 to 8.10 mg x kg(-1), 19.50 to 49.16 mg x kg(-1), respectively. There was a significantly positive linear relationship between concentrations of <span class="hlt">14</span><span class="hlt">C</span>-SOC and <span class="hlt">14</span><span class="hlt">C</span>-MBC (R2 = 0.957**, P < 0.01). The <span class="hlt">14</span><span class="hlt">C</span>-DOC and <span class="hlt">14</span><span class="hlt">C</span>-MBC as proportions of total DOC, MBC, were 5.65%-24.91% and 4.23%-20.02%, respectively. Moreover, the distribution and transformation of microbes-assimilated-derived C had a greater influence on the dynamics of DOC and MBC than that on the dynamics of SOC. These data provide new insights into the importance of microorganisms in the fixation of atmospheric CO2 and of the potentially significant contributions made by microbial autotrophy to terrestrial C cycling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014DSRI...91...94P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014DSRI...91...94P"><span id="translatedtitle">Does the <span class="hlt">14</span><span class="hlt">C</span> method estimate net photosynthesis? II. Implications from cyclostat studies of marine phytoplankton</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pei, Shaofeng; Laws, Edward A.</p> <p>2014-09-01</p> <p>Two species of marine phytoplankton, Isochrysis galbana and Chlorella kessleri, were grown in a continuous culture system on a 12-h:12-h light:dark cycle of illumination under nitrate-limited growth conditions. At growth rates of ~1 d-1, production rates estimated from <span class="hlt">14</span><span class="hlt">C</span> uptake were not significantly different from production rates estimated from changes in particulate organic carbon (POC) and total organic carbon (TOC). At growth rates of ~0.35 d-1, however, production rates based on uptake of <span class="hlt">14</span><span class="hlt">C</span> significantly (p<0.05) overestimated production rates based on changes in POC and TOC in all cases for C. kessleri and after 24 h for I. galbana. The ratio of production based on <span class="hlt">14</span><span class="hlt">C</span> uptake to production based on changes in POC and TOC concentrations was in all cases higher after 24 h than after 12 h. The extent of overestimation after a 24-h incubation at ~0.35 d-1 was about 23 and 40% in the cases of I. galbana and C. kessleri, respectively. Dark respiration rates estimated from changes in <span class="hlt">14</span><span class="hlt">C</span> activity during the dark period were lower than the rates estimated from changes of POC and TOC concentrations during the 12 h of darkness because only about 73% of the carbon respired during the dark period had been fixed during the previous 12-h photoperiod. The fact that the <span class="hlt">14</span><span class="hlt">C</span> method tends to overestimate net carbon assimilation by a greater percentage at low growth rates than at high growth rates probably reflects the greater efficiency of intracellular recycling of respired CO2 at high growth rates. The fact that the extent of overestimation is greater when cells are grown on a light:dark cycle probably reflects the fact that not all carbon respired in the dark was fixed during the previous photoperiod and that intracellular recycling of respired CO2 during the photoperiod is inefficient during some phases of the synchronized growth that tends to be entrained by light:dark cycles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4681490','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4681490"><span id="translatedtitle">Metabolic disposition of the anti-cancer agent [<span class="hlt">14</span><span class="hlt">C</span>]laromustine in male rats</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Nassar, Ala F.; Wisnewski, Adam; King, Ivan</p> <p>2015-01-01</p> <p>Laromustine (VNP40101M, also known as Cloretazine) is a novel sulfonylhydrazine alkylating (anticancer) agent. This article describes the use of quantitative whole-body autoradiography (QWBA) and mass balance to study the tissue distribution, the excretion mass balance and pharmacokinetics after intravenous administration of [<span class="hlt">14</span><span class="hlt">C</span>]VNP40101M to rats. A single 10 mg/kg IV bolus dose of [<span class="hlt">14</span><span class="hlt">C</span>]VNP40101M was given to rats. The recovery of radioactivity from the Group 1 animals over a 7-day period was an average of 92.1% of the administered dose, which was accounted for in the excreta and carcass. Most of the radioactivity was eliminated within 48 h via urine (48%), with less excreted in feces (5%) and expired air accounted for (11%). The plasma half-life of [<span class="hlt">14</span><span class="hlt">C</span>]laromustine was approximately 62 min and the peak plasma concentration (Cmax) averaged 8.3 μg/mL The QWBA study indicated that the drug-derived radioactivity was widely distributed to tissues through 7 days post-dose after a single 10 mg/kg IV bolus dose of [<span class="hlt">14</span><span class="hlt">C</span>]VNP40101M to male pigmented Long–Evans rats. The maximum concentrations were observed at 0.5 or 1 h post-dose for majority tissues (28 of 42). The highest concentrations of radioactivity were found in the small intestine contents at 0.5 h (112.137 μg equiv/g), urinary bladder contents at 3 h (89.636 μg equiv/g) and probably reflect excretion of drug and metabolites. The highest concentrations in specific organs were found in the renal cortex at 1 h (28.582 μg equiv/g), small intestine at 3 h (16.946 μg equiv/g), Harderian gland at 3 h (12.332 μg equiv/g) and pancreas at 3 h (12.635 μg equiv/g). Concentrations in the cerebrum (1.978 μg equiv/g), cerebellum (2.109 μg equiv/g), medulla (1.797 μg equiv/g) and spinal cord (1.510 μg equiv/g) were maximal at 0.5 h post-dose and persisted for 7 days. The predicted total body and target organ exposures for humans given a single 100μCi IV dose of [<span class="hlt">14</span><span class="hlt">C</span>]VNP40101M were well within the medical guidelines</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/948849','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/948849"><span id="translatedtitle">Flux of carbon from <span class="hlt">14</span><span class="hlt">C</span>-enriched leaf litter throughout a forest soil mesocosm</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Froberg, Mats J.; Hanson, Paul J; Trumbore, Susan E.; Swanston, Christopher W.; Todd Jr, Donald E</p> <p>2009-01-01</p> <p>The role of DOC for the build-up of soil organic carbon pools is still not well known, but it is thought to play a role in the transport of carbon to a greater depth where it becomes more stable. The aim of this study was to elucidate within-year dynamics of carbon transport from litter to the O (Oe and Oa) and A horizons. Mesocosms with constructed soil profiles were used to study dynamics of C transport from <span class="hlt">14</span><span class="hlt">C</span>-enriched (about 1000 ) leaf litter to the Oe/Oa and A horizons as well as the mineralization of leaf litter. The mesocosms were placed in the field for 17 months during which time fluxes and <span class="hlt">14</span><span class="hlt">C</span> content of DOC and CO2 were measured. Changes in <span class="hlt">14</span><span class="hlt">C</span> in leaf litter and bulk soil C pools were also recorded. Significant simultaneous release and immobilization of DOC occurring in both the O and A horizons was hypothesized. Contrary to our hypothesis, DOC released from the labeled Oi horizon was not retained within the Oe/Oa layer. DOC originating in the unlabeled Oe/Oa layer was also released for transport. Extensive retention of DOC occurred in the A horizon. DOC leaching from A horizon consisted of a mix of DOC from different sources, with a main fraction originating in the A horizon and a smaller fraction leached from the overlaying horizons. The C and <span class="hlt">14</span><span class="hlt">C</span> budget for the litter layer also indicated a surprisingly large amount of carbon with ambient Δ<span class="hlt">14</span><span class="hlt">C</span>-signature to be respired from this layer. Data for this site also suggested significant contributions from throughfall to dissolved organic carbon (DOC) transport into and respiration from the litter layer. The results from this study showed that DOC retentionwas low in the O horizon and therefore not important for the O horizon carbon budget. In the A horizon DOC retention was extensive, but annual DOC input was small compared to C stocks and therefore not important for changes in soil C on an annual timescale.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..11.1710V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.1710V"><span id="translatedtitle">OSL versus <span class="hlt">14</span><span class="hlt">C</span> dating of sandy pedosediments as paleo-ecological archives in cultural landscapes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>van Mourik, J. M.</p> <p>2009-04-01</p> <p>Late glacial aeolian coversand dominates the surface geology of an extensive area in Northwest Europe. During prehistoric and early historic time, forest grazing, wood cutting and shifting cultivation gradually transformed natural forest into heath land. Subsequently the use of the heath for the production of organic manure during the period of plaggen agriculture (from early Middle Ages to the invention of chemical fertilizers around 1900 AD) resulted in the comeback of active sand drifting. Locally the coversand landscape transformed into a driftsand landscape with characteristic new landforms and soils. Important parts of soil archives in these cultural landscapes are fimic covers, records of a long period of agricultural history and polycyclic driftsand deposits, records of alternating instable and stable phases in landscape development. Based on pollen analysis of fimic covers and buried humic soil horizons in polycyclic driftsand sequences, a lot of paleoecological information is available to reconstruct the development of soils and landforms in cultural landscapes, but we need a correct chronological framework to correlate information of various sources and sites. Traditionally <span class="hlt">14</span><span class="hlt">C</span> dating was applied on humic horizons of buried soils and a <span class="hlt">14</span><span class="hlt">C</span> based chronological framework was designed to estimate the accumulation rate of fimic covers and to date stable and instable periods in polycyclic driftsand profiles. However, <span class="hlt">14</span><span class="hlt">C</span> dates of extracted SOM (soil organic matter) are not always reliable. Firstly, in studies of fimic antrosols arose disagreement between paleoecological and historical interpretators of the evolution of these antrosols. The results of soil micromorphology and <span class="hlt">14</span><span class="hlt">C</span> dating, applied on separated SOM fractions (humine, humic acids and fulvic acids) showed that SOM, present in fimic horizons, consists of a complex mix of compounds of different ages and sources. Secondly, <span class="hlt">14</span><span class="hlt">C</span> dates of buried humic soil horizons are not always reliable. In thin</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/967755','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/967755"><span id="translatedtitle">A Brief Review of the Application of <span class="hlt">14</span><span class="hlt">C</span> in Terrestrial Carbon Cycle Studies</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Guilderson, T; Mcfarlane, K</p> <p>2009-10-22</p> <p>An over-arching goal of the DOE TCP program is to understand the mechanistic controls over the fate, transport, and residence time of carbon in the terrestrial biosphere. Many of the modern process and modeling studies focus on seasonal to interannual variability. However, much of the carbon on the landscape and in soils is in separate reservoirs with turnover times that are multi-decadal to millennial. It is the controls on these longer term pools or reservoirs that is a critical unknown in the face of rising GHGs and climate change and uncertainties of the terrestrial biosphere as a future global sink or source of atmospheric CO{sub 2} [eg., Friedlingstein et al., 2006; Govindasamy et al., 2005; Thompson et al., 2004]. Radiocarbon measurements, in combination with other data, can provide insight into, and constraints on, terrestrial carbon cycling. Radiocarbon (t{sub 1/2} 5730yrs) is produced naturally in the stratosphere when secondary neutrons generated by cosmic rays collide with {sup 14}N atoms [Libby 1946; Arnold and Libby, 1949]. Upon formation, {sup <span class="hlt">14</span>}<span class="hlt">C</span> is rapidly oxidized to CO and then to CO{sub 2}, and is incorporated into the carbon cycle. Due to anthropogenic activities, the amount of {sup <span class="hlt">14</span>}<span class="hlt">C</span> in the atmosphere doubled in the mid/late 1950s and early 1960s from its preindustrial value of {sup <span class="hlt">14</span>}<span class="hlt">C</span>/{sup 12}C ratio of 1.18 x 10{sup -12} [eg., Nydal and Lovseth, 1983]. Following the atmospheric weapons test ban in 1963, the {sup <span class="hlt">14</span>}<span class="hlt">C</span>/{sup 12}C ratio, has decreased due to the net isotopic exchange between the ocean and terrestrial biosphere [eg., Levin and Hessheimer, 2000] and a dilution effect due to the burning of {sup <span class="hlt">14</span>}<span class="hlt">C</span>-free fossil fuel carbon, the 'Suess Effect' [Suess, 1955]. In the carbon cycle literature, radiocarbon measurements are generally reported as {Delta}{sup <span class="hlt">14</span>}<span class="hlt">C</span>, which includes a correction for mass dependent fractionation [Stuiver and Polach, 1977]. In the context of carbon cycle studies radiocarbon measurements can be used to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25464038','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25464038"><span id="translatedtitle">Tritium and <span class="hlt">14</span><span class="hlt">C</span> background levels in pristine aquatic systems and their potential sources of variability.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Eyrolle-Boyer, Frédérique; Claval, David; Cossonnet, Catherine; Zebracki, Mathilde; Gairoard, Stéphanie; Radakovitch, Olivier; Calmon, Philippe; Leclerc, Elisabeth</p> <p>2015-01-01</p> <p>Tritium and (<span class="hlt">14</span>)<span class="hlt">C</span> are currently the two main radionuclides discharged by nuclear industry. Tritium integrates into and closely follows the water cycle and, as shown recently the carbon cycle, as does (<span class="hlt">14</span>)<span class="hlt">C</span> (Eyrolle-Boyer et al., 2014a, b). As a result, these two elements persist in both terrestrial and aquatic environments according to the recycling rates of organic matter. Although on average the organically bound tritium (OBT) activity of sediments in pristine rivers does not significantly differ today (2007-2012) from the mean tritiated water (HTO) content on record for rainwater (2.4 ± 0.6 Bq/L and 1.6 ± 0.4 Bq/L, respectively), regional differences are expected depending on the biomass inventories affected by atmospheric global fallout from nuclear testing and the recycling rate of organic matter within watersheds. The results obtained between 2007 and 2012 for (<span class="hlt">14</span>)<span class="hlt">C</span> show that the levels varied between 94.5 ± 1.5 and 234 ± 2.7 Bq/kg of C for the sediments in French rivers and across a slightly higher range of 199 ± 1.3 to 238 ± 3.1 Bq/kg of C for fish. This variation is most probably due to preferential uptake of some organic carbon compounds by fish restraining (<span class="hlt">14</span>)<span class="hlt">C</span> dilution with refractory organic carbon and/or with old carbonates both depleted in (<span class="hlt">14</span>)<span class="hlt">C</span>. Overall, most of these ranges of values are below the mean baseline value for the terrestrial environment (232.0 ± 1.8 Bq/kg of C in 2012, Roussel-Debet, 2014a) in relation to dilution by the carbonates and/or fossil organic carbon present in aquatic systems. This emphasises yet again the value of establishing regional baseline value ranges for these two radionuclides in order to account for palaeoclimatic and lithological variations. Besides, our results obtained from sedimentary archive investigation have confirmed the delayed contamination of aquatic sediments by tritium from the past nuclear tests atmospheric fallout, as recently demonstrated from data chronicles (Eyrolle</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/20863727','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/20863727"><span id="translatedtitle">Measurements of the {sup 25}Mg({sup 11}B,{sup 12}C){sup 24}Na and {sup 25}Mg({sup 11}B,{sup 10}Be){sup <span class="hlt">26</span>}<span class="hlt">Al</span> proton transfer reactions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Faria, P. N. de; Lichtenthaeler, R.; Guimaraes, V.; Lepine-Szily, A.; Benjamim, E. A.; Lima, G. F.; Moro, A. M.</p> <p>2006-08-15</p> <p>Angular distributions for the {sup 11}B+{sup 25}Mg elastic scattering, {sup 25}Mg({sup 11}B,{sup 12}C){sup 24}Na proton pickup, and {sup 25}Mg({sup 11}B,{sup 10}Be){sup <span class="hlt">26</span>}<span class="hlt">Al</span> stripping reactions have been measured at E{sub {sup 11}B}=35 MeV. The angular distributions have been analyzed by the distorted-waves Born approximation calculations using the code fresco. The spectroscopic factors for the overlaps <{sup 25}Mg|{sup <span class="hlt">26</span>}<span class="hlt">Al</span>>,<{sup 25}Mg|{sup 24}Na> for the ground state and excited states of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> and {sup 24}Na have been obtained and compared to previous measurements and shell-model calculations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10129618','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10129618"><span id="translatedtitle">Proton production cross sections of {sup <span class="hlt">14</span>}<span class="hlt">C</span> from silicon and oxygen: Implications for cosmic-ray studies</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sisterson, J.M.; Jull, A.J.T.; Beverding, A.</p> <p>1993-12-31</p> <p>The production rates of {sup <span class="hlt">14</span>}<span class="hlt">C</span> from proton spallation of silicon, and oxygen have been measured over a wide range of energies from 31 to 450 MeV. {sup <span class="hlt">14</span>}<span class="hlt">C</span> was measured by accelerator mass spectrometry (AMS) after extraction of carbon from the samples by melting in a flow of oxygen.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16088336','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16088336"><span id="translatedtitle">The influence of Bacillus subtilis RB<span class="hlt">14</span>-<span class="hlt">C</span> on the development of Rhizoctonia solani and indigenous microorganisms in the soil.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Szczech, Magdalena; Shoda, Makoto</p> <p>2005-05-01</p> <p>The effect of soil inoculation with an antagonistic strain Bacillus subtilis RB<span class="hlt">14</span>-<span class="hlt">C</span> on the development of Rhizoctonia solani and changes occurring in soil and rhizosphere microbial communities were studied. RB<span class="hlt">14</span>-<span class="hlt">C</span> was added to the soil as a water suspension of the cells or as a broth culture. Application of cell suspensions to non-planted soil reduced the number of culturable bacteria. The density of R. solani and the number of filamentous fungi were not significantly affected by RB<span class="hlt">14</span>-<span class="hlt">C</span>. A similar effect was observed in the rhizosphere of tomato plants growns in bacterized soil. Broth cultures of RB<span class="hlt">14</span>-<span class="hlt">C</span> suppressed R. solani 1 d after inoculation, but after 3 d there was no difference in the pathogen density between soil amended with broth culture and control soil. In microcosm studies, cell suspensions of RB<span class="hlt">14</span>-<span class="hlt">C</span> also did not inhibit growth of R. solani on filters buried in soil. However, an inhibitory effect was obtained when a broth culture of the bacterium was used. The effect of RB<span class="hlt">14</span>-<span class="hlt">C</span> on fungal biomass was also estimated by measurement of ergosterol concentration in soil. It was found that ergosterol was mostly derived from R. solani and that there were no significant differences in its content between untreated soil and soil treated with RB<span class="hlt">14</span>-<span class="hlt">C</span>. The results suggest that suppression of Rhizoctonia damping-off by B. subtilis RB<span class="hlt">14</span>-<span class="hlt">C</span> probably is not related to the reduction of the pathogen population in the soil.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.192..166H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.192..166H"><span id="translatedtitle">Cross-checking groundwater age by 4He and <span class="hlt">14</span><span class="hlt">C</span> dating in a granite, Tono area, central Japan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hasegawa, Takuma; Nakata, Kotaro; Tomioka, Yuichi; Goto, Kazuyuki; Kashiwaya, Koki; Hama, Katsuhiro; Iwatsuki, Teruki; Kunimaru, Takanori; Takeda, Masaki</p> <p>2016-11-01</p> <p>Groundwater dating was performed simultaneously by the 4He and <span class="hlt">14</span><span class="hlt">C</span> methods in granite of the Tono area in central Japan. Groundwater was sampled at 30 packed-off sections of six 1000-m boreholes. 4He concentrations increased and <span class="hlt">14</span><span class="hlt">C</span> concentrations decreased along a groundwater flow path on a topographic gradient. 4He ages were calculated by using the in situ 4He production rate derived from the porosity, density, and U and Th content of the rock, neglecting external flux. <span class="hlt">14</span><span class="hlt">C</span> ages were calculated with a noncorrected model in which the initial <span class="hlt">14</span><span class="hlt">C</span> content was 100 percent of the modern radiocarbon level (Co = 100 pmC), a statistical model using the average <span class="hlt">14</span><span class="hlt">C</span> content of tritium-bearing samples (Co = 46.4 pmC), and a δ13C model based on the isotopic mass balance. Although the absolute <span class="hlt">14</span><span class="hlt">C</span> ages calculated by the models were different, the relative <span class="hlt">14</span><span class="hlt">C</span> ages were almost identical. The relative <span class="hlt">14</span><span class="hlt">C</span> ages were considered reliable because dissolved inorganic carbon has no significant geochemical reactions in granite. The relation between the 4He ages and the noncorrected <span class="hlt">14</span><span class="hlt">C</span> ages was [4He age] = 1.15 [<span class="hlt">14</span><span class="hlt">C</span> age] + 7200 (R2 = 0.81), except in the discharge area. The slope of this relation was equivalent to unity, which indicates that the 4He accumulation rate is confirmed by the relative <span class="hlt">14</span><span class="hlt">C</span> ages. Moreover, the accumulated 3He/4He ratio was equivalent to that derived from the 6Li(α,n)3H reaction in granite. These results show that the accumulated He is of crustal origin, produced in situ without external flux, except in the discharge area. The intercept value of 7200 a implies that the <span class="hlt">14</span><span class="hlt">C</span> concentrations were diluted due to geochemical reactions. Tritium-bearing samples supported this result. Simultaneous measurements make it feasible to estimate the accumulation rate of 4He and initial dilution of <span class="hlt">14</span><span class="hlt">C</span>, which cannot be done with a single method. Cross-checking groundwater dating has the potential to provide more reliable groundwater ages. The circulation time of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GGG....17..833G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GGG....17..833G"><span id="translatedtitle">A comparison of U/Th and rapid-screen <span class="hlt">14</span><span class="hlt">C</span> dates from Line Island fossil corals</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grothe, Pamela R.; Cobb, Kim M.; Bush, Shari L.; Cheng, Hai; Santos, Guaciara M.; Southon, John R.; Lawrence Edwards, R.; Deocampo, Daniel M.; Sayani, Hussein R.</p> <p>2016-03-01</p> <p>Time-consuming and expensive radiometric dating techniques limit the number of dates available to construct absolute chronologies for high-resolution paleoclimate reconstructions. A recently developed rapid-screen <span class="hlt">14</span><span class="hlt">C</span> dating technique reduces sample preparation time and per sample costs by 90%, but its accuracy has not yet been tested on shallow-water corals. In this study, we test the rapid-screen <span class="hlt">14</span><span class="hlt">C</span> dating technique on shallow-water corals by comparing 44 rapid-screen <span class="hlt">14</span><span class="hlt">C</span> dates to both high-precision <span class="hlt">14</span><span class="hlt">C</span> dates and U/Th dates from mid- to late-Holocene fossil corals collected from the central tropical Pacific (2-4°N, 157-160°W). Our results show that 42 rapid-screen <span class="hlt">14</span><span class="hlt">C</span> and U/Th dates agree within uncertainties, confirming closed-system behavior and ensuring chronological accuracy. However, two samples that grew ˜6500 years ago have calibrated <span class="hlt">14</span><span class="hlt">C</span> ages ˜1000 years younger than the corresponding U/Th ages, consistent with diagenetic alteration as indicated by the presence of 15-23% calcite. Mass balance calculations confirm that the observed dating discrepancies are consistent with <span class="hlt">14</span><span class="hlt">C</span> addition and U removal, both of which occur during diagenetic calcite recrystallization. Under the assumption that aragonite-to-calcite replacement is linear through time, we estimate the samples' true ages using the measured <span class="hlt">14</span><span class="hlt">C</span> and U/Th dates and percent calcite values. Results illustrate that the rapid-screen <span class="hlt">14</span><span class="hlt">C</span> dates of Holocene-aged fossil corals are accurate for samples with less than 2% calcite. Application of this rapid-screen <span class="hlt">14</span><span class="hlt">C</span> method to the fossil coral rubble fields from Kiritimati Island reveal significant chronological clustering of fossil coral across the landscape, with older ages farther from the water's edge.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1814001O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1814001O"><span id="translatedtitle">Source apportionment of carbonaceous aerosol in Sao Paulo using 13C and <span class="hlt">14</span><span class="hlt">C</span> measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Oyama, Beatriz; Andrade, Maria de Fatima; Holzinger, Rupert; Röckmann, Thomas; Meijer, Harro A. J.; Dusek, Ulrike</p> <p>2016-04-01</p> <p>The Metropolitan Area of Sao Paulo is affected by high aerosol concentrations, which contain a large fraction of organic material. Up to date, not much is known about the composition and origin of the organic aerosol in this city. We present the first source apportionment of the carbonaceous aerosol fraction in Sao Paulo, using stable (13C) and radioactive carbon isotopes (<span class="hlt">14</span><span class="hlt">C</span>). <span class="hlt">14</span><span class="hlt">C</span> provides a clear-cut distinction between fossil sources, which contain no <span class="hlt">14</span><span class="hlt">C</span>, and contemporary sources such as biofuels, biomass burning, or biogenic sources, which contain a typical contemporary <span class="hlt">14</span><span class="hlt">C</span>/12C ratio. 13C can be used to distinguish C3 plants, such as maize and sugarcane, from C4 plants. This can help to identify a possible impact of sugarcane field burning in the rural areas of Sao Paulo State on the aerosol carbon in the city. In the first part of the study, we compare two tunnel studies: Tunnel 1 is frequented only by light duty vehicles, which run mainly on mixtures of gasoline with ethanol (gasohol, 25% ethanol and 85% gasoline) or hydrated ethanol (5% water and 95% ethanol). Tunnel 2 contains a significant fraction of heavy-duty diesel vehicles, and therefore the fraction of biofuels in the average fleet is lower. Comparison of <span class="hlt">14</span><span class="hlt">C</span> in organic and elemental carbon (OC and EC) shows that in both tunnels there is no significant contribution of biofuels to EC. Combusting ethanol-gasoline fuels in a vehicle engine does apparently not result in significant EC formation from ethanol. Biofuels contribute around 45% to OC in Tunnel 1 an only 20% in Tunnel 2, reflecting a strong impact of diesel vehicles in Tunnel 2. In the second part of the study we conduct a source apportionment of ambient aerosol carbon collected in a field study during winter (July-August) 2012. Ambient EC has two main sources, vehicular emissions and biomass burning. We estimate a contribution of vehicular sources to EC of roughly 90% during weekdays and 80% during weekends, using the <span class="hlt">14</span><span class="hlt">C</span> values measured in</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6268333','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6268333"><span id="translatedtitle">Uptake of (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)deoxyglucose into brain of young rats with inherited hydrocephalus</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Richards, H.K.; Bucknall, R.M.; Jones, H.C.; Pickard, J.D.</p> <p>1989-02-01</p> <p>The effect of hydrocephalus on cerebral glucose utilization as reflected by deoxyglucose uptake has been examined in rats with inherited hydrocephalus at 10, 20, and 28 days after birth using a semiquantitative method. Injection of (<span class="hlt">14</span><span class="hlt">C</span>)deoxyglucose intraperitoneally was followed by freezing the brain, sectioning, and quantitative autoradiography of 10 brain regions. Brain (<span class="hlt">14</span><span class="hlt">C</span>) concentration, cortical thickness, and plasma glucose concentrations were measured. Maximal thinning of the cerebral cortex had already occurred by 10 days after birth, although obvious symptoms such as gait disturbance developed after 20 days. In control rats, the cerebral isotope concentration was lower and more homogeneous at 10 days than at 20 or 28 days, which may be a reflection of the use of metabolic substrates other than glucose in younger animals. In order to make comparisons between control and hydrocephalic groups, tissue isotope concentrations were normalized to cerebellar cortex which was not affected by the hydrocephalus at any age. In hydrocephalic rats at 10 and 20 days, the concentration of (<span class="hlt">14</span><span class="hlt">C</span>) was lower in all areas except the inferior colliculi and pons but the reduction was only significant in the sensory-motor cortex at 10 days and in the caudate nuclei at 20 days. By 28 days after birth, all areas except the cerebellum (six cortical regions, inferior colliculi, pons, and caudate) had significantly lower isotope concentrations in the hydrocephalic group. It is concluded that cerebral glucose metabolism is significantly reduced by 28 days after birth in H-Tx rats with congenital hydrocephalus and that less marked reductions occur prior to 28 days.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.B23C0460C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.B23C0460C"><span id="translatedtitle">Concentrations and <span class="hlt">14</span><span class="hlt">C</span> age of nonstructural carbon in California oaks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Czimczik, C. I.; Druffel-Rodriguez, K.; Trumbore, S. E.</p> <p>2008-12-01</p> <p>Plants store photosynthetic assimilates as nonstructural carbon (NSC), mainly glucose, fructose, sucrose, and starch. NSC fuels processes such as respiration and growth. Research suggests that NSC represents a significant fraction of a plant's annual C budget, but temporal dynamics of NSC are poorly understood. We used concentration and radiocarbon (<span class="hlt">14</span><span class="hlt">C</span>) measurements of NSC to investigate how temporal dynamics of NSC vary with life strategy and throughout a species' range. In Mediterranean environments, oaks have developed two strategies (evergreen and deciduous) to cope with drought. Within California, the uncertainty of annual winter rain increases from north to south. We compared two evergreen and deciduous species: Coastal and Interior live oak (Quercus agrifolia and wislizenii) and Valley and Blue oak (Q. lobata and douglasii). Samples (4 mm cores to 20 cm depth at dbh) were taken in 2008 before leaf-out and fall at five sites which represent an inland to coast temperature gradient from high to low summer temperatures as well as a north- south precipitation gradient. Sugars were isolated by shaking in methanol-water and quantified using a spectrometric micro-plate technique. Starch was isolated by boiling in ethanol followed by HCl digestion and quantified manometrically. <span class="hlt">14</span><span class="hlt">C</span> contents were measured by AMS. Preliminary findings indicate that in live oaks, winter sugar concentrations are constant throughout the tree and across sites, while <span class="hlt">14</span><span class="hlt">C</span> concentrations increase towards a tree's center. This suggests that the NSC pool oaks is not well mixed. Future work will elucidate whether plants can access these older NSC stores.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1929062','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1929062"><span id="translatedtitle">Longevity and growth of Acacia tortilis; insights from <span class="hlt">14</span><span class="hlt">C</span> content and anatomy of wood</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Andersen, Gidske L; Krzywinski, Knut</p> <p>2007-01-01</p> <p>Background Acacia tortilis is a keystone species across arid ecosystems in Africa and the Middle East. Yet, its life-history, longevity and growth are poorly known, and consequently ongoing changes in tree populations cannot be managed in an appropriate manner. In other arid areas parenchymatic bands marking growth zones in the wood have made dendrochronological studies possible. The possibilities for using pre- and post-bomb <span class="hlt">14</span><span class="hlt">C</span> content in wood samples along with the presence of narrow marginal parenchymatic bands in the wood is therefore tested to gain further insight into the age, growth and growth conditions of A. tortilis in the hyper-arid Eastern Desert of Egypt. Results Based on age scenarios and the Gompertz growth equation, the age of trees studied seems to be from 200 up to 650 years. Annual radial growth estimated from calibrated dates based on the post-bomb <span class="hlt">14</span><span class="hlt">C</span> content of samples is up to 2.4 mm, but varies both spatially and temporally. Parenchymatic bands are not formed regularly. The correlation in band pattern among trees is poor, both among and within sites. Conclusion The post-bomb <span class="hlt">14</span><span class="hlt">C</span> content of A. tortilis wood gives valuable information on tree growth and is required to assess the age scenario approach applied here. This approach indicates high longevities and slow growth of trees. Special management measures should therefore be taken at sites where the trend in tree population size is negative. The possibilities for dendrochronological studies based on A. tortilis from the Eastern Desert are poor. However, marginal parenchymatic bands can give insight into fine scale variation in growth conditions and the past management of trees. PMID:17573964</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/793636','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/793636"><span id="translatedtitle">Low-Charge State AMS for High Throughput <span class="hlt">14</span><span class="hlt">C</span> Quantification</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ognibene, T.J.; Roberts, M.L.; Southon, J.R.; Vogel, J.S.</p> <p>2000-06-16</p> <p>Accelerator mass spectrometry (AMS) quantifies attomole (10{sup -18}) amounts of {sup <span class="hlt">14</span>}<span class="hlt">C</span> in milligram sized samples. This sensitivity is used to trace nutrients, toxins and therapeutics in humans and animals at less than {micro}g/kg doses containing 1-100 nCi of {sup <span class="hlt">14</span>}<span class="hlt">C</span>. Widespread use of AMS in pharmaceutical development and biochemical science has been hampered by the size and expense of the typical spectrometer that has been developed for high precision radiocarbon dating. The precision of AMS can be relaxed for biochemical tracing, but sensitivity, accuracy and throughput are important properties that must be maintained in spectrometers designed for routine quantification. We are completing installation of a spectrometer that will maintain the high throughput of our primary spectrometer but which requires less than 20% of the floor space and of the cost. Sensitivity and throughput are kept high by using the LLNL intense cesium sputter ion source with solid graphitic samples. Resultant space-charge effects are minimized by careful modeling to find optimal ion transport in the spectrometer. A long charge-changing ''stripper gas'' volume removes molecular isobars at potentials of a few hundred kiloVolts, reducing the size of the accelerating component. Fast ion detectors count at high rates to keep a wide dynamic range for <span class="hlt">14</span> <span class="hlt">C</span> concentrations. Solid sample presentation eliminates the sample cross contamination that degrades accuracy and the effects of ''memory'' in the ion source. Automated processes are under development for conversion of liquid and solid biological samples to the preferred graphitic form for the ion source.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014HESSD..11.5953A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014HESSD..11.5953A"><span id="translatedtitle">Using <span class="hlt">14</span><span class="hlt">C</span> and 3H to understand groundwater flow and recharge in an aquifer window</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Atkinson, A. P.; Cartwright, I.; Gilfedder, B. S.; Cendón, D. I.; Unland, N. P.; Hofmann, H.</p> <p>2014-06-01</p> <p>Knowledge of groundwater residence times and recharge locations are vital to the sustainable management of groundwater resources. Here we investigate groundwater residence times and patterns of recharge in the Gellibrand Valley, southeast Australia, where outcropping aquifer sediments of the Eastern View Formation form an "aquifer window" that may receive diffuse recharge and recharge from the Gellibrand River. To determine recharge patterns and groundwater flowpaths, environmental isotopes (3H, <span class="hlt">14</span><span class="hlt">C</span>, δ13C, δ18O, δ2H) are used in conjunction with groundwater geochemistry and continuous monitoring of groundwater elevation and electrical conductivity. Despite the water table fluctuating by 0.9-3.7 m annually producing estimated recharge rates of 90 and 372 mm yr-1, residence times of shallow (11-29 m) groundwater determined by <span class="hlt">14</span><span class="hlt">C</span> ages are between 100 and 10 000 years. 3H activities are negligible in most of the groundwater and groundwater electrical conductivity in individual areas remains constant over the period of study. Although diffuse local recharge is evident, the depth to which it penetrates is limited to the upper 10 m of the aquifer. Rather, groundwater in the Gellibrand Valley predominantly originates from the regional recharge zone, the Barongarook High, and acts as a regional discharge zone where upward head gradients are maintained annually, limiting local recharge. Additionally, the Gellibrand River does not recharge the surrounding groundwater and has limited bank storage. <span class="hlt">14</span><span class="hlt">C</span> ages and Cl concentrations are well correlated and Cl concentrations may be used to provide a first-order estimate of groundwater residence times. Progressively lower chloride concentrations from 10 000 years BP to the present day are interpreted to indicate an increase in recharge rates on the Barongarook High.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/866404','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/866404"><span id="translatedtitle">Binding of mescaline with subcellular fractions upon incubation of brain cortex slices with [<span class="hlt">14</span><span class="hlt">C</span>] mescaline.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Datta, R K; Antopol, W; Ghosh, J J</p> <p>1977-01-01</p> <p>Incubation of brain cortex slices in the presence of glucose resulted in the permeation of about 65% of [<span class="hlt">14</span><span class="hlt">C</span>] mescaline into slices. Of this, about one-third radioactivity was bound with nuclei, mitochondria, microsomes, and ribosomes. Dialysis of subcellular fractions did not markedly reduce the amounts of radioactivity bound to the fractions. The permeation into slices and the binding of mescaline to subcellular fractions were fairly time-dependent, but were inhibited by the presence of potassium cyanide, or by the absence of glucose and by heating to 80 degrees C for 1 min.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21032666','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21032666"><span id="translatedtitle">Searching For A Suitable Gas Ion Source For <span class="hlt">14</span><span class="hlt">C</span> Accelerator Mass Spectrometry</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Reden, Karl von; Roberts, Mark; Han, Baoxi; Schneider, Robert; Wills, John</p> <p>2007-08-10</p> <p>This paper describes the challenges facing <span class="hlt">14</span><span class="hlt">C</span> Accelerator Mass Spectrometry (AMS) in the effort to directly analyze the combusted effluent of a chromatograph (or any other continuous source of sample material). An efficient, low-memory negative gas ion source would greatly simplify the task to make this a reality. We discuss our tests of a microwave ion source charge exchange canal combination, present an improved design, and hope to generate more interest in the negative ion source community to develop a direct-extraction negative carbon gas ion source for AMS.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6184053','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6184053"><span id="translatedtitle">A batch preparation method for graphite targets with low background for AMS [sup <span class="hlt">14</span>]<span class="hlt">C</span> measurements</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kitagawa, Hiroyuki International Research Center for Japanese Studies, Nishikyp-ku, Kyoto ); Masuzawa, Toshiyuki; Matsumoto, Eiji ); Makamura, Toshio )</p> <p>1993-01-01</p> <p>The authors have developed a method of graphitization from CO[sub 2] samples for accurate [sup <span class="hlt">14</span>]<span class="hlt">C</span> measurements by accelerator mass spectrometry. Their batch method, using a sealed Vycor tube, reduces the risk of contamination during graphitization and makes it possible to prepare many samples in a short time (typically 20 samples per day). They also describe details of the target-preparation method involving carbon isotopic fractionation during graphitization, yield of graphite from CO[sub 2], ion-beam intensity of the target, and background (or blank) level estimated using bituminous coal.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20189632','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20189632"><span id="translatedtitle">Transformation of (<span class="hlt">14</span>)<span class="hlt">C</span>-pyrimidynyloxybenzoic herbicide ZJ0273 in aerobic soils.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Haiyan, Wang; Zhiyang, Yu; Ling, Yue; Ailiang, Han; Yanfei, Zhang; Juying, Li; Qingfu, Ye; Zhengmin, Yang; Long, Lu</p> <p>2010-04-15</p> <p>A soil metabolism study of propyl 4-(2-(4,6-dimethoxypyrimidin-2-yloxy)benzylamino)benzoate (ZJ0273), a novel broad-spectrum herbicide, was carried out using (<span class="hlt">14</span>)<span class="hlt">C</span> labeled on two different rings, i.e., [pyrimidine-4,6-(<span class="hlt">14</span>)<span class="hlt">C</span>] ZJ0273 and [benzyl-U-(<span class="hlt">14</span>)<span class="hlt">C</span>] ZJ0273. Ultralow liquid scintillation counting and LC-MS/MS were used to identify the degradation intermediates and quantify their dynamics in aerobic soils. Four aromatic intermediates, 4-(2-(4,6-dimethoxypyrimidin-2-yloxy)benzylamino)benzoic acid (M1), 4-(2-(4,6-dimethoxypyrimidin-2-yloxy)benzamido)benzoic acid (M2), 2-(4,6-dimethoxypyrimidin-2-yloxy)benzoic acid (M3), and 4,6-dimethoxypyrimidin-2-ol (M4), were identified and their identity was further confirmed against authentic standards. Analysis of metabolites suggested two degradation pathways: (1) Upon loss of the propyl group, M1 was produced via hydrolysis of propyl 4-(2-(4,6-dimethoxypyrimidin-2-yloxy)benzylamino)benzoate after which the C-N bond between rings A and B was cleaved by oxidation and biochemical degradation to yield M3, which was further converted into M4 and finally mineralized to CO(2); and (2) the first step was the same as in pathway 1, but M1 first underwent a carbonylation to form M2. The C-N bond between rings A and B of M2 was cleaved by hydrolysis to yield M3. Dynamic changes in the four metabolites in aerobic soils were also investigated by HPLC coupled analysis of radioactivity of isolated peaks. After a 100-day incubation, 1.7-9.7% of applied (<span class="hlt">14</span>)<span class="hlt">C</span> was found as M1, 0.3-1.1% as M2, 14.5-20.9% as M3, and 3.7-6.7% as M4 in the soils, and pH appeared to be the most influential soil property affecting the formation and dissipation of these metabolites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/69528','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/69528"><span id="translatedtitle">{sup 223}Ra nuclear spectroscopy in {sup <span class="hlt">14</span>}<span class="hlt">C</span> cluster radioactivity</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hourany, E.; Berrier-Ronsin, G.; Elayi, A.; Hoffmann-Rothe, P.; Mueller, A.C.; Rosier, L.; Rotbard, G.; Renou, G.; Liebe, A.; Poenaru, D.N.</p> <p>1995-07-01</p> <p>The energy spectrum of {sup <span class="hlt">14</span>}<span class="hlt">C</span> ions emitted from {sup 223}Ra sources implanted at ISOLDE has been measured with the spectrometer SOLENO. The highest statistics (899 events) and the best energy resolution (90 keV) obtained so far in cluster decay allow a real spectroscopic study. Hindrance factors for transitions to the ground state and first excited state in {sup 209}Pb, and limits for the next three low-lying states, hae been determined. The data can be explained by a parent wave function containing mainly a {ital i}{sub 11/2} spherical component.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5802613','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5802613"><span id="translatedtitle">Excised barley root uptake of several /sup <span class="hlt">14</span>/<span class="hlt">C</span> labeled organic compounds</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>McFarlane, C.; Wickliff, C.</p> <p>1985-01-01</p> <p>Many organic pollutants potentially are available for uptake by plants and thus bioaccumulation and food contamination. One method of studying uptake is with excised roots, a technique extensively used with plant nutrients. A similar method was developed and used to evaluate uptake patterns of several /sup <span class="hlt">14</span>/<span class="hlt">C</span>-labeled organic chemicals. Uptake rate constants for the chemicals tested occurred in the following order: captan approx. phenol > aniline > ethanol approx. indole approx. trifluralin approx. propanil > 1,2,4-trichlorobenzene(TCB) > nitrobenzene approx. atrazine > bromacil > simazine > monuron.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/7213192','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/7213192"><span id="translatedtitle">[The auditory pathway in guinea pigs. A [<span class="hlt">14</span><span class="hlt">C</span>]2-deoxyglucose study (author's transl)].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Strutz, J; Beck, C; Schmidt, C L</p> <p>1981-01-01</p> <p>The auditory pathway of guinea pigs was labeled with [<span class="hlt">14</span><span class="hlt">C</span>]-deoxyglucose after mon- or binaural stimulation with farfield white noise in a sound-proof chamber. In the autoradiographs, all auditory nuclei were labeled. The highest metabolic effects were seen in the dorsal cochlear nucleus, the lateral superior olivary nucleus, and in the inferior colliculus. No selective labeling was observed in the auditory cortex. Monaural stimulation depressed the metabolic activity contralaterally in the ventral cochlear nucleus and ipsilaterally in the medial nucleus of the trapezoid body, the dorsomedial periolivary nucleus, and in the inferior colliculus. PMID:7213192</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.4187H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.4187H"><span id="translatedtitle">Accelerated degradation of <span class="hlt">14</span><span class="hlt">C</span>-atrazine in an atrazine adapted field soil from Belgium</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hamacher, Georg; Jablonowski, Nicolai David; Martinazzo, Rosane; Accinelli, Cesare; Köppchen, Stephan; Langen, Ulrike; Linden, Andreas; Krause, Martina; Burauel, Peter</p> <p>2010-05-01</p> <p>Atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] is one of the most widely used herbicides in the world. Atrazine is considered to be mobile in soil and has often been characterized as a rather recalcitrant compound in the environment. In the present study the accelerated atrazine degradation in an agriculturally used soil was examined. Soil samples were collected from a Belgian field which was used for corn-plantations and was regularly treated with atrazine during the last 30 years. The experiment was conducted under controlled laboratory conditions (GLP) using <span class="hlt">14</span><span class="hlt">C</span>-labelled and unlabelled atrazine in accordance to the reported field application dose of 1 mg kg-1. Triplicates of treated subsamples were incubated at 50% WHCmax and under slurry conditions (1:4 soil:solution ratio, using distilled water) in the dark at 20° C. Control samples were collected at an adjacent pear orchard where no atrazine or other triazine pesticides application was reported. After 92 days of incubation, the mineralized amount of atrazine reached 83% of the initially applied <span class="hlt">14</span><span class="hlt">C</span>-activity in the atrazine treated soil for the slurry setup. A maximum of atrazine mineralization was observed in the treated field soil between 6 and 7 days of incubation for both, 50% WHCmax and slurry setups. The total <span class="hlt">14</span><span class="hlt">C</span>-atrazine mineralization was equally high for 50% WHCmax in the atrazine treated soil. After an extended lag-phase in comparison to the treated soil the overall mineralizat