Science.gov

Sample records for 14c 26al 36cl

  1. Leaching of /sup 14/C and /sup 36/Cl from Hanford reactor graphite

    SciTech Connect

    Gray, W.J.; Morgan, W.C.

    1988-12-01

    The leach rates of /sup 14C/ and /sup 36Cl/ were measured on solid cylindrical samples of graphite prepared from a bar retrieved from one of the surplus Hanford production reactors. Static leach tests were conducted in deionized water and Hanford ground water at temperatures of 20/degree/C to 90/degree/C for 8 weeks. The graphite samples were completely submerged in the leachant, and the entire volume of leachant was changed and analyzed weekly. The leach rates of both /sup 14C/ and /sup 36Cl/ decreased with time and appeared to approach steady-state values that were independent of temperature in the case of /sup 36Cl/ but decreased with temperature in the case of /sup 14C/. Both radionuclides leached more slowly in Hanford ground water. The data are compared with previously measured and estimated leach rates. Implications of the data regarding possible rate-limiting mechanisms are also discussed. 4 refs., 18 figs., 4 tabs.

  2. 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.

  3. "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

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    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.

  5. 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

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

    2016-02-01

    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 ((26)Al and (36)Cl) and stable ((3)He and (21)Ne) nuclides in quartz, dolomite/calcite, sanidine, and diopside. The obtained results suggest that there is accordance in the values obtained by applying (26)Al, (36)Cl, and (21)Ne 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 (205)Pb derived from pp-neutrino and fast cosmic-ray muons, respectively, which is an important prerequisite for the LOREX experiment.

  6. 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

  7. 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.

  8. 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.

  9. 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

  10. Recent results of measurements of the {sup 14}N(n,p){sup 14}C, {sup 35}Cl(n,p){sup 35}S, {sup 36}Cl(n,p){sup 36}S, and {sup 36}Cl(n,{alpha}){sup 33}P reaction cross sections

    SciTech Connect

    Gledenov, Y.M.; Salatski, V.I.; Sedyshev, P.V.; Sedysheva, M.V.; Koehler, P.E.; Vesna, V.A.; Okunev, I.S.

    1995-02-05

    Experiments are reported for measuring the cross section of the {sup 14}N(n,p){sup 14}C reaction over the neutron energy range from thermal energy to 150 keV at the IBR-30 pulsed booster at JNR, Dubna and the WWR-M reactor at INR, Kiev. The reaction cross section values were found for the thermal energy and for the neutron energies of 24 keV, 54 keV, 144 keV. The {sup 36}Cl(n,p){sup 36}S cross section was measured for the neutron energies from thermal energy to approximately 800 keV at the neutron source of LANSCE, Los Alamos. The contributions of the {sup 36}Cl(n,p){sup 36}S and {sup 36}Cl(n,{alpha}){sup 33}P reactions to resonances at 0.9 keV and 1.3 keV were identified. Also, at the WWR-M reactor of PINR, Gatchina, preliminary measurements of the {sup 36}Cl(n,p){sup 36}S cross section at the thermal neutron energy were conducted. The {sup 35}Cl(n,p){sup 35}S reaction cross section was measured at the IBR-30 pulsed booster. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  11. 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.

  12. 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.

  13. 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.

  14. Problems of contamination in 36Cl studies

    NASA Astrophysics Data System (ADS)

    Bird, J. R.; Shahgholi, N.; Jenkinson, A.; Smith, A.; Fifield, L. K.; Ophel, T.; Allan, G.

    1990-12-01

    The joint ANSTO/ANU 36Cl program has now measured more than 700 samples from many different locations. During the course of this work, a variety of contamination problems have affected a small number of results which have provided valuable information on the effects of ion source cross-talk, sample preparation and storage procedures and sources of high- 36Cl material. A sample of Weeks Island halite is processed along with every batch of field samples and the observed ratio provides a clear distinction between normal batches and those subject to contamination. Over three years, the long-term average ratio of {36Cl}/{Cl} for normal halite samples is (1 ± 1) × 10 -15. The sample handling procedures developed during the course of this work provide a useful guide to the techniques that must be used to achieve the sensitivity limits which are potentially available using AMS.

  15. 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.

  16. An Alluvial Surface Chronology Based on Cosmogenic 36Cl Dating, Ajo Mountains (Organ Pipe Cactus National Monument), Southern Arizona

    NASA Astrophysics Data System (ADS)

    Liu, Beiling; Phillips, Fred M.; Pohl, Molly M.; Sharma, Pankaj

    1996-01-01

    A chronology of alluvial surfaces on piedmont slopes below the western Ajo Mountains, southern Arizona, has been obtained using cosmogenic 36Cl accumulation and AMS radiocarbon dating. The apparent 36Cl ages of individual boulders range from 520,000 to 13,000 yr, and the 14C ages of organic material in the two young terraces are 2750-2350 and 17,800 cal yr B.P. The sequence of 36Cl ages is consistent with the apparent stratigraphic order, but groupings of similar ages for different surfaces appear to result from repeated reworking of older surfaces associated with the deposition of younger ones. The youngest surface gave a distribution of 36Cl ages about 30,000 yr older than the 14C and soil ages; however, this distribution had 36Cl ages that overlapped with 36Cl ages from active channels and hillslopes. We attribute the older-than-expected exposure ages of sampled boulders to inheritance of 36Cl while residing near the surface during very slow erosion on the mountain front. Our results show that although cosmogenic nuclide accumulation can help establish chronologies for surfaces in piedmont settings, care must be used in evaluating the effects of complex exposure histories.

  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 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.

  19. 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.

    1987-12-31

    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 {sup 36}Cl/Cl ratio 0.5 m below the surface. The structure of the {sup 36}Cl bomb pulse at the other location was much more complex, and the 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.

  20. 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.

  1. {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.

  2. 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.

  3. 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

  4. Measuring astrophysically relevant 36Cl production cross sections

    NASA Astrophysics Data System (ADS)

    Anderson, Tyler; Skulski, Michael; Ostdiek, Karen; Lu, Wenting; Clark, Adam; Nelson, Austin; Beard, Mary; Collon, Philippe

    2016-09-01

    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 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 33S(α,p)36Cl cross section at various energies in the range of 0.70-2.42 MeV/A, and found them to be systematically under predicted by Hauser-Feshbach statistical model codes TALYS and NON-SMOKER, highlighting the need for more empirical data for these cross sections. Recent results of the re-measurement of the 33S(α,p)36Cl reaction, providing greater coverage of the same energy range as Bowers et al., will be presented. Future plans for measurement of other 36Cl producing reactions will also be discussed.

  5. 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

  6. Half life of /sup 26/Al

    SciTech Connect

    Norris, T.L.; Gancarz, A.J.; Rokop, D.J.; Thomas, K.W.

    1983-01-01

    The half-life of /sup 26/Al has been redetermined because of suggestions of an error in the accepted value based on its use in calculating /sup 21/Ne production rates from cosmic rays in meteorites. Two solutions of /sup 26/Al were analyzed for the specific radioactivity and mass spectrometric determination of the /sup 26/Al concentration. The half-life obtained for /sup 26/Al was 7.05 x 10/sup 5/ years +- 3.7% at the two sigma level. This is identical to the accepted value of 7.16 x 10/sup 5/ years and indicates that problems with the /sup 21/Ne production rate is not due to an erroneous half-life.

  7. 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

  8. On the Production of 36Cl by High-Energy Particles in Thin- and Thick- Target Experiments

    NASA Astrophysics Data System (ADS)

    Schiekel, Th.; Herpers, U.; Sudbrock, F.; Gloris, M.; Leya, I.; Michel, R.; Synal, H.-A.; Suter, M.

    1995-09-01

    Knowledge about the production of cosmogenic nuclides in meteorites, planetary surfaces and cosmic dust is elementary for various cosmophysical studies. Completely known it would contain information about the constancy and the spectral distribution of cosmic radiation and it would allow to decipher the irradiation history of matter under the condition of solar and galactic cosmic ray exposure. Cosmic ray particle interactions with matter can be described by a thin-target approach. In this case integral excitation functions for the main target elements have to be combined with depth dependent spectra of primary and secondary particles, see for instance [1]. On the other hand thick-target simulation experiments have been accomplished [2,3] from which production rates can be directly determined. Both approaches have been investigated and successfully validated for short- as well as for long-lived nuclides, e.g ^10Be and ^26Al [3]. Now extending our investigations on the nuclide ^36Cl irradiation experiments with initial proton energies ranging from 45 MeV up to 2600 MeV have been carried out using the "stacked-foil-technique". We have yet determined integral excitation functions for proton induced production of ^36Cl from the most relevant as well as for some minor target elements in meteorites (e.g. Ca, Ti, V, Mn, Fe, Ni, Co, Cu) providing necessary data for the thin-target approach. ^36Cl in the individual targets has been measured via the ultrasensitive accelerator mass spectrometry after a radiochemical separation. For a validation of the above mentioned model calculations based on the thin-target approach by Michel et al. [1], the depth dependent elemental production rates of ^36Cl from the main target elements have been measured in two artificial meteorites made out of gabbro and iron (radii 25 cm and 10 cm respectively) irradiated isotropically with 1,6 GeV protons [3,4]. The theoretical calculations agree reasonably well with our experimental results for the

  9. 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.

  10. Estimation of groundwater residence time using the 36Cl bomb pulse.

    PubMed

    Tosaki, Yuki; Tase, Norio; Sasa, Kimikazu; Takahashi, Tsutomu; Nagashima, Yasuo

    2011-01-01

    We propose a methodology for estimating the residence time of groundwater based on bomb-produced (36)Cl. Water samples were collected from 28 springs and 2 flowing wells located around Mt. Fuji, Central Japan. (36)Cl/Cl ratios in the water samples, determined by accelerator mass spectrometry (AMS), were between 43 × 10(-15) and 412 × 10(-15). A reference time series of the above-background (i.e., bomb-derived) (36)Cl concentration was constructed by linearly scaling the background-corrected Dye-3 data according to the estimated total bomb-produced (36)Cl fallout in the Mt. Fuji area. Assuming piston flow transport, estimates of residence time were obtained by comparing the measured bomb-derived (36)Cl concentrations in spring water with the reference curve. The distribution of (36)Cl-based residence times is basically consistent with that of tritium-based estimates calculated from data presented in previous studies, although the estimated residence times differ between the two tracers. This discrepancy may reflect chlorine recycling via vegetation or the relatively small change in fallout rate, approximately since 1975, which would give rise to large uncertainties in (36)Cl-based estimates of recharge for the period, approximately since 1975. Given the estimated ages for groundwater from flowing wells, dating based on a (36)Cl bomb pulse may be more reliable and sensitive for groundwater recharged before 1975, back as far as the mid-1950s.

  11. Application of 36Cl as a dating tool for modern groundwater

    NASA Astrophysics Data System (ADS)

    Tosaki, Yuki; Tase, Norio; Massmann, Gudrun; Nagashima, Yasuo; Seki, Riki; Takahashi, Tsutomu; Sasa, Kimikazu; Sueki, Keisuke; Matsuhiro, Takeshi; Miura, Taichi; Bessho, Kotaro; Matsumura, Hiroshi; He, Ming

    2007-06-01

    The 36Cl/Cl ratios of groundwater samples were measured by accelerator mass spectrometry (AMS) in order to investigate the potential use of 36Cl as a dating tool for modern groundwater. Groundwater samples were obtained from several piezometers in the Oderbruch in northeastern Germany. The shallow confined aquifer of the area is mainly recharged by the infiltration from the River Oder. From the results of measurements, the pre-bomb and the recent background 36Cl/Cl ratios in the basin of the Oder were estimated to be 7-9 × 10-14. The 36Cl fallout values estimated from the 36Cl/Cl ratios of the Oderbruch samples, which were dated by the 3H/3He method, show good agreement with Dye-3 ice core data. These results suggest that the distribution of 36Cl in groundwaters reflects the influence of the 36Cl bomb pulse. This, in turn, suggests that the distribution of 36Cl/Cl in modern groundwaters could reveal groundwater ages and flow systems in a region.

  12. 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

  13. 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.

  14. 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.

  15. Ultra-trace analysis of 36Cl by accelerator mass spectrometry: an interlaboratory study.

    PubMed

    Merchel, S; Bremser, W; Alfimov, V; Arnold, M; Aumaître, G; Benedetti, L; Bourlès, D L; Caffee, M; Fifield, L K; Finkel, R C; Freeman, S P H T; Martschini, M; Matsushi, Y; Rood, D H; Sasa, K; Steier, P; Takahashi, T; Tamari, M; Tims, S G; Tosaki, Y; Wilcken, K M; Xu, S

    2011-07-01

    A first international (36)Cl interlaboratory comparison has been initiated. Evaluation of the final results of the eight participating accelerator mass spectrometry (AMS) laboratories on three synthetic AgCl samples with (36)Cl/Cl ratios at the 10(-11), 10(-12), and 10(-13) level shows no difference in the sense of simple statistical significance. However, more detailed statistical analyses demonstrate certain interlaboratory bias and underestimation of uncertainties by some laboratories. Following subsequent remeasurement and reanalysis of the data from some AMS facilities, the round-robin data indicate that (36)Cl/Cl data from two individual AMS laboratories can differ by up to 17%. Thus, the demand for further work on harmonising the (36)Cl-system on a worldwide scale and enlarging the improvement of measurements is obvious.

  16. Interaction of (3)H(+) (as HTO) and (36)Cl(-) (as Na(36)Cl) with crushed granite and corresponding fracture infill material investigated in column experiments.

    PubMed

    Štamberg, K; Palágyi, Š; Videnská, K; Havlová, V

    The transport of (3)H(+) (as HTO) and (36)Cl(-) (as Na(36)Cl) was investigated in the dynamic system, i.e., in the columns filled with crushed pure granite and fracture infill of various grain sizes. The aim of column experiments was to determine important transport parameter, such as the retardation, respectively distribution coefficients, Peclet numbers and hydrodynamic dispersion coefficients. Furthermore, the research was focused to quantification of the effect of grain size on migration of studied radionuclides. The experimental breakthrough curves were fitted by a model based on the erfc-function, assuming a linear reversible equilibrium sorption/desorption isotherm, and the above mentioned transport parameters were determined. The results showed that influence of grain size on sorption of (3)H(+) and (36)Cl(-) was negligible. Retardation and distribution coefficients of both tracers converged to one and zero, respectively, in case of all fractions of crushed granite and infill material. Generally, the presumed ion exclusion of (36)Cl in anionic form was proved under given conditions, only very weak one seems to exist in a case of infill material. In principal, both radionuclides behaved as non-sorbing, conservative tracers. On the other hand, the influence of grain size on Peclet numbers value and on dispersion coefficient was observed for both crystalline materials, namely in agreement with theoretical suppositions that the values of Peclet numbers decrease with increasing grain size and values of dispersion coefficient increase.

  17. Bomb-test 36Cl measurements in Vostok snow (Antarctica) and the use of 36Cl as a dating tool for deep ice cores

    NASA Astrophysics Data System (ADS)

    Delmas, R. J.; Beer, J.; Synal, H.-A.; Muscheler, R.; Petit, J.-R.; Pourchet, M.

    2004-11-01

    A large pulse of atmospheric 36Cl generated by a limited number of nuclear tests peaked in the late 1950s to early 1960s. The corresponding enhanced 36Cl deposition is seen in various glaciological archives in the Northern Hemisphere. The profile of the bomb spike recorded in firn layers at Vostok Station, central East Antarctica, has been measured by employing accelerator mass spectrometry (AMS). The records obtained from two well-dated data sets collected in snow pits in 1997 and 1998 show a broad 36Cl peak, beginning as early as the 1940s and reaching its maximum in the 1960s. The signal is followed by a long-lasting tail up to the surface. This pattern is totally unexpected. We show that the results, unlike the Greenland data, can be explained by a mobility of HCl in the Antarctic firn. This experiment demonstrates the instability of gaseous Cl- deposits, a phenomenon which has important implications for the use of natural cosmogenic 36Cl radionuclides as a reliable dating tool for deep ice cores from low-accumulation areas. However, during glacial times, under favourable atmospheric chemistry conditions this dating method may still be applicable. Snow metamorphism and ventilation are assumed to be the two main physical processes responsible for the observed patterns.

  18. 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.

  19. Cosmogenic /sup 36/Cl production rates in meteorites and the lunar surface

    SciTech Connect

    Nishiizumi, K.; Kubik, P.W.; Elmore, D.; Reedy, R.C.; Arnold, J.R.

    1988-01-01

    Activity-versus-depth profiles of cosmic-ray-produced /sup 36/Cl were measured in metal from two cores each in the St. Severin and Jilin chondrites and in lunar core 15008. Production of /sup 36/Cl in these samples range from high-energy reactions with Fe and Ni to low-energy reactions with Ca and K and possibly neutron-capture reactions with /sup 35/Cl. The cross sections used in the Reedy-Arnold model for neutron-induced reactions were adjusted to get production rates that fit the measured /sup 36/Cl activities in St. Severin metal and in the lunar soil of core 15008. The /sup 36/Cl in metal from St. Severin has a fairly flat activity-versus-depth profile, unlike most other cosmogenic nuclides in bulk samples from St. Severin, which increase in concentration with depth. In metal from Jilin, a decrease in /sup 36/Cl was observed near its center. The length of Jilin's most recent cosmic-ray exposure was /approximately/0.5 My. Lunar core 15008 has an excess in /sup 36/Cl of about 4 dpm/kg near its surface that was produced by solar-proton-induced reactions. The calculated production rates are consistent with these measured trends in 15008. 39 refs., 4 figs., 3 tabs.

  20. Transplacental passage of 26Al from pregnant rats to fetuses and 26Al transfer through maternal milk to suckling rats

    NASA Astrophysics Data System (ADS)

    Yumoto, S.; Nagai, H.; Matsuzaki, H.; Kobayashi, T.; Tada, W.; Ohki, Y.; Kakimi, S.; Kobayashi, K.

    2000-10-01

    Aluminium (Al) is toxic to the growth of fetuses and sucklings. However, the incorporation of Al into fetuses and sucklings in the periods of gestation and lactation has not been well clarified because Al lacks a suitable isotope for a tracer experiment. In this study, we used 26Al (a radioisotope of Al with half-life of 716,000 yr) as a tracer, and measured 26Al incorporation into fetuses and sucklings by accelerator mass spectrometry (AMS). To investigate Al incorporation into fetuses through transplacental passage, 26Al ( 26AlCl 3) was subcutaneously injected into pregnant rats on day 15 of gestation. 26Al was also subcutaneoulsy injected into lactating rats from day 1 to day 20 postpartum. By day 20 of gestation, 0.2% of the 26Al injected into a pregnant rat had been transferred to the fetuses, and 26Al was detected in the brain and liver of the fetuses. On day 9 postpartum, high levels of 26Al were demonstrated in the brain, liver, kidneys and blood of suckling rats. It is concluded that 26Al subcutaneously injected into pregnant rats and/or lactating rats is incorporated into their offspring through transplacental passage and/or maternal milk.

  1. 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

  2. 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.

  3. 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.

  4. Radioactive 26Al from massive stars in the Galaxy.

    PubMed

    Diehl, Roland; Halloin, Hubert; Kretschmer, Karsten; Lichti, Giselher G; Schönfelder, Volker; Strong, Andrew W; von Kienlin, Andreas; Wang, Wei; Jean, Pierre; Knödlseder, Jürgen; Roques, Jean-Pierre; Weidenspointner, Georg; Schanne, Stephane; Hartmann, Dieter H; Winkler, Christoph; Wunderer, Cornelia

    2006-01-05

    Gamma-rays from radioactive 26Al (half-life approximately 7.2 x 10(5) years) provide a 'snapshot' view of continuing nucleosynthesis in the Galaxy. The Galaxy is relatively transparent to such gamma-rays, and emission has been found concentrated along its plane. This led to the conclusion that massive stars throughout the Galaxy dominate the production of 26Al. On the other hand, meteoritic data show evidence for locally produced 26Al, perhaps from spallation reactions in the protosolar disk. Furthermore, prominent gamma-ray emission from the Cygnus region suggests that a substantial fraction of Galactic 26Al could originate in localized star-forming regions. Here we report high spectral resolution measurements of 26Al emission at 1808.65 keV, which demonstrate that the 26Al source regions corotate with the Galaxy, supporting its Galaxy-wide origin. We determine a present-day equilibrium mass of 2.8 (+/- 0.8) solar masses of 26Al. We use this to determine that the frequency of core collapse (that is, type Ib/c and type II) supernovae is 1.9 (+/- 1.1) events per century.

  5. ^26Al Beam Production and its Application to Nuclear Astrophysics

    NASA Astrophysics Data System (ADS)

    Richard, Brad

    2012-10-01

    Presumably produced during the supernova stage of stellar evolution, ^26Al offers unique opportunities to better understand the processes of nucleosynthesis occurring in pre-SN phases of stellar evolution and within the Galactic disk. When decaying to ^26Mg, ^26Al emits a unique 1.8MeV gamma ray, detectable by satellite telescopes. The production and destruction pathways of ^26Al is a key portion of understanding the on-going stellar nucleosynthesis. In order to measure the cross-section of ^26Al(n, p) ^26Mg at the astrophysical relevant energies, an indirect method, called the Trojan Horse Method(THM), is utilized. The THM allows the study of neutron induced reactions at astrophysical energies via the d break-up. This method requires the three-body cross section for the ^26Al(d, p ^26Mg)H reaction to be measured at a beam of 60 MeV. This requires that the ^26Al secondary beam is produced by the MARS facility at Cyclotron institute of Texas A&M University from a primary ^26Mg beam (E 16MeV/u) impinging on a H2 target. ^26Al beam was then degraded to 2.25MeV/u energy by means of a Beryllium foil. The obtained results will be shown and discussed in details together with the features of the obtained intense and pure beam.

  6. Vertical groundwater flow estimated from the bomb pulse of 36Cl and tritiogenic 3He

    NASA Astrophysics Data System (ADS)

    Mahara, Y.; Ohta, T.

    2011-12-01

    The boring well was approximately excavated to 400 m depth from the ground surface on the tableland in the Central Shimokita Peninsula, Japan. Collecting pore-water, some fresh boring cores were sampled on the site during the excavation of borehole. Samples of groundwater were collected by using the sampling device with the water inflating packer system to protect various contaminations, after excavating the borehole. The atmospheric maximum concentration in bomb pulse in the northern hemisphere was reported to observe in 1955 for 36Cl and in 1963 for 3H, respectively. Since the half-life of 36Cl is much longer than 3H, the decay loss of 36Cl was negligible small for a short time until sampling groundwater in 2001 and 2003. On the other hand, the half-life of 3H is very short compared with that of 36Cl. Most of 3H was converted into the tritiogenic 3He in groundwater for the past 38 years after rainwater infiltrating toward the groundwater table. Profiles of dissolved 4He concentration, tritiogenic 3He and 36Cl/Cl ratio were observed in groundwater of the borehole. The total dissolved 4He concentration ranged from 5.8×10-8 at the ground surface to 7.5×10-8 ccSTP/g at the depth of 200 m below the ground surface and it was almost equilibrated with the atmospheric 4He in pore-water (Fig. 1). The bomb pulses of tritiogenic 3He and 36Cl were left from the depth of 101 m below the ground surface to the depth of 132 m, respectively (Figs. 2 and 3). There was a slight difference in the location between the bomb pulse of 36Cl and that of tritiogenic 3He. The downward flow velocity of groundwater were simply estimated to be 2.8 m/y from the marked position of bomb pulse in the profile of 36Cl/Cl ratio and to be 2.7 m/y from the position of the bomb pulse peak of tritiogenic 3He, separately. These two rough estimations were good agreed with each other. The estimation suggests that the vertical flow of groundwater on the tableland is approximated with the downward piston

  7. Nucleogenic 36Cl, 236U and 239Pu in uranium ores

    NASA Astrophysics Data System (ADS)

    Wilcken, K. M.; Fifield, L. K.; Barrows, T. T.; Tims, S. G.; Gladkis, L. G.

    2008-08-01

    The nucleogenic isotopes 36Cl, 236U and 239Pu are produced naturally in subsurface environments via neutron capture of thermal and epithermal neutrons. Concentrations are, however, very low and accelerator mass spectrometry (AMS) is required for quantitative measurements. A particular challenge is presented by the measurement of 236U/ 238U ratios down to the level of 10 -13 that is expected from rocks with low uranium concentration. Here, we present the AMS methodology that has been developed at the ANU for measuring 236U/ 238U ratios at this level. The more established methodologies for 36Cl and 239Pu measurements are also summarised. These capabilities are then used to characterize the 36Cl, 236U and 239Pu concentrations in a range of uranium ores. A simple model of the neutron production and capture processes in subsurface environments has been developed and is presented. It is shown that nucleogenic 36Cl, 236U and 239Pu can be used to determine both thermal and epithermal neutron fluxes in subsurface environments. Potential applications include uranium exploration and monitoring of the environmental impact of uranium mining.

  8. 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.

  9. Implications of halide leaching on 36Cl studies at Yucca Mountain, Nevada

    NASA Astrophysics Data System (ADS)

    Lu, Guoping; Sonnenthal, Eric L.; Bodvarsson, Gudmundur S.

    2003-12-01

    Chlorine 36 was generated from nuclear tests in the 1950s and 1960s and has been used to identify fast flow paths at Yucca Mountain, the proposed repository for high-level nuclear waste [, 1997, 1998]. Bomb pulse 36Cl, brought into the subsurface by infiltrating rainwater, presumably resides along fracture surfaces because of the extremely low rock matrix permeability. However, leaching a rock sample to extract this salt inevitably extracts pore water chloride (Cl) and rock matrix chloride, thereby making it difficult to obtain reproducible measurements or detect the specific bomb pulse signatures. Complexities introduced by these sources of older chloride include dilution of bomb pulse 36Cl/Cl ratios for samples from strata with a high Cl concentration, variations in measured ratios as a function of leaching time, rock chip size, and the differing effects of active leaching from those of passive leaching. This work provides both a conceptual model and a mathematical solution for the leaching processes and examines the role of sample leaching in the 36Cl studies of Yucca Mountain rocks. An analytical solution is derived for the diffusion of Cl and 36Cl in composite media (rock matrix and water) to accommodate variable diffusivity. This solution is subsequently used to develop a leaching model that takes into account bomb pulse signal, matrix pore water, and relatively hard to leach components (isolated fluid inclusion and mineral boundary salts). The model is then applied to samples from stratigraphic units at Yucca Mountain to obtain leachate concentrations from different setup methods (protocols), including duration, chip size, and gravitational settling of the water-rock mixture. The model results show that the probability of detecting a 36Cl/Cl bomb pulse signal is severely diminished under longer leaching times and smaller rock fragment sizes and that leaching times of 1 to 10 hours are most likely to be successful in detecting a bomb pulse signal. Bomb pulse

  10. 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...

  11. 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.

  12. 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.

  13. Depth dependence of soil carbonate accumulation based on cosmogenic 36Cl dating

    NASA Astrophysics Data System (ADS)

    Liu, Beiling; Phillips, Fred M.; Elmore, David; Sharma, Pankaj

    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 36Cl-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 36Cl-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.

  14. Cosmogenic 26Al/10Be surface production ratio in Greenland

    NASA Astrophysics Data System (ADS)

    Corbett, Lee B.; Bierman, Paul R.; Rood, Dylan H.; Caffee, Marc W.; Lifton, Nathaniel A.; Woodruff, Thomas E.

    2017-02-01

    The assumed value for the cosmogenic 26Al/10Be surface production rate ratio in quartz is an important parameter for studies investigating the burial or subaerial erosion of long-lived surfaces and sediments. Recent models and data suggest that the production ratio is spatially variable and may be greater than originally thought. Here we present measured 26Al/10Be ratios for 24 continuously exposed bedrock and boulder surfaces spanning 61-77°N in Greenland. Empirical measurements, such as ours, include nuclides produced predominately by neutron-induced spallation with percent-level contributions by muon interactions. The slope of a York regression line fit to our data is 7.3 ± 0.3 (1σ), suggesting that the 26Al/10Be surface production ratio exceeds the commonly used value of 6.75, at least in the Arctic. A higher 26Al/10Be production ratio has implications for multinuclide cosmogenic isotope studies because it results in greater modeled burial durations and erosion rates.

  15. 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.

  16. 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.

  17. 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.

  18. 26Al and 10Be Activities of Lodranites and Winona

    NASA Astrophysics Data System (ADS)

    Herzog, G. F.; Xue, S.; Klein, J.; Juenemann, D.; Middleton, R.

    1993-07-01

    Noble gas measurements by [1] indicate that four lodranites LEW 88280, Lodran (a fall), MAC 88177, and Yamato 791491 have the same cosmic ray exposure age of a few million years. The elevated ^22Ne/^21Ne ratios of these lodranites, from 1.22 to 1.28 [1], suggest that shielding was light and production rates appreciably lower than in average chondrites. Cosmic-ray irradiation in space for, say, 4 My would bring ^26Al and ^10Be to within 2% and 16% of their respective saturation values. Thus measurement of ^26Al may provide information about production rates and shielding and ^10Be about exposure age. We separated magnetically metal- and silicate-rich material from the four lodranites mentioned above and from Winona. The ^26Al and/or ^10Be activities (Table 1) were measured by accelerator mass spectrometry [2] with the statistical 1-sigma precision shown; the activities are thought to have an overall accuracy of 6-8%. Although the metal phases were etched with HF, they retained some silicate. To get a quantitative indication of the amounts of silicate present, the Mg concentrations in aliquots of the dissolved metal samples (Table 1) were measured by ICP/MS. The Mg, Al, Ca, Ti, Mn, and Fe contents of the silicate phases were determined by DCP emission spectrometry [3]. The measured activities in silicates from LEW 88280, Lodran, and Y 791491 resemble one another closely: The average ^26Al and ^10Be activities are 50.9 and 16.7 dpm/kg compared to estimated production rates of about 55 and 23 dpm/kg. These results lead to an exposure age of ~3.3 My, but do not indicate substantial lowering of production rates. The ^26Al and ^10Be contents of MAC 88177 are about half the values expected at saturation under normal shielding and are lower than those in the other three lodranites. These results are consistent with the very light shielding inferred from the exceptionally high ^22Ne/^21Ne ratio of 1.28, and perhaps with some lowering due to terrestrial age. Kirsten et al. [4

  19. 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.

  20. Estimation of thermal neutron fluences in the concrete of proton accelerator facilities from 36Cl production

    NASA Astrophysics Data System (ADS)

    Bessho, K.; Matsumura, H.; Miura, T.; Wang, Q.; Masumoto, K.; Hagura, H.; Nagashima, Y.; Seki, R.; Takahashi, T.; Sasa, K.; Sueki, K.; Matsuhiro, T.; Tosaki, Y.

    2007-06-01

    The thermal neutron fluence that poured into the shielding concrete of proton accelerator facilities was estimated from the in situ production of 36Cl. The thermal neutron fluences at concrete surfaces during 10-30 years of operation were in the range of 1012-1014 n/cm2. The maxima in thermal neutron fluences were observed at ≈5-15 cm in the depths analyzed for 36Cl/35Cl by AMS. These characteristics imply that thermalization of neutrons occurred inside the concrete. Compared to the several tens of MeV cyclotrons, secondary neutrons penetrate deeper into the concrete at the high-energy accelerators possessing acceleration energies of 400 MeV and 12 GeV. The attenuation length of neutrons reflects the energy spectra of secondary neutrons emitted by the nuclear reaction at the beam-loss points. Increasing the energy of secondary neutrons shifts the maximum in the thermal neutron fluences to deeper positions. The data obtained in this study will be useful for the radioactive waste management at accelerator facilities.

  1. The in vitro reduction of sodium [36Cl]chlorate in bovine ruminal fluid.

    PubMed

    Oliver, C E; Bauer, M L; Caton, J S; Anderson, R C; Smith, D J

    2007-08-01

    Sodium chlorate effectively reduces or eliminates gram-negative pathogenic bacteria in the gastrointestinal tracts of live cattle. Limitations to the in vivo efficacy of chlorate are its rapid absorption from the gastrointestinal tract and its presumed reduction to chloride within the gastrointestinal tract. We hypothesized that chlorate would be reduced via ruminal bacteria in a ruminal in vitro system and that the reduction of chlorate would be influenced by the dietary for-age:concentrate ratio; thus, 4 ruminally cannulated steers were fed 20 or 80% concentrate diets in a crossover design. Ruminal fluid was collected in 2 periods and dispensed into in vitro tubes containing sodium [36Cl]chlorate, which was sufficient for 100 or 300 mg/L final chlorate concentrations. The tubes were incubated for 0, 1, 4, 8, 16, or 24 h; autoclaved, control ruminal fluid, fortified with sodium [36Cl]chlorate, was incubated for 24 h. Chlorate remaining in each sample was measured by liquid scintillation counting after [36Cl]chloride was precipitated with silver nitrate. A preliminary study indicated that chlorite, a possible intermediate in the reduction of chlorate, had a half-life of approximately 4.5 min in freshly collected (live) ruminal fluid; chlorite was, therefore, not specifically measured in ruminal incubations. The chlorate dose did not affect in vitro DM digestion (P > or = 0.11), whereas in vitro DM digestibility was decreased (P < or = 0.05) by 80% forage content. By 24 h, 57.5 +/- 2.6% of the chlorate remained in 100-mg/L incubations, whereas 78.2 +/- 2.6% of the chlorate remained in the 300-mg/L incubations. When the data were expressed on a concentration basis (mg/L), diet had no effect (P > or = 0.18) on chlorate reduction; however, when chlorate reduction was expressed on a percentage basis, chlorate reduction tended to be greater (P > or = 0.09) at 8 and 16 h in the incubations containing the low-concentrate diet. Chlorate remaining in autoclaved controls at

  2. Measurement of low levels of 26Al from meteorite samples.

    PubMed

    Johnston, Peter N; Hult, Mikael; Altzitzoglo, Timotheos

    2002-01-01

    As part of an intercomparison to resolve discrepancies between accelerator mass spectrometry results and radiometric results, the 26Al activity in four meteorite samples was measured using ultra low-level gamma-ray spectrometry in the underground laboratory HADES. Although reference sources were used, extensive use was made of computer modelling to determine corrections for absorption, coincidence summing between gamma rays in the decays and annihilation radiation following positron emission. Directional correlation corrections were also taken into account. The limiting uncertainties in these measurements arose from counting statistics of 5-9%. Some computer modelling was undertaken to determine optimum geometry for this type of intercomparison involving gamma-ray spectrometry.

  3. (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.

  4. A new Holocene eruptive history of Erebus volcano, Antarctica using cosmogenic 3He and 36Cl

    NASA Astrophysics Data System (ADS)

    Parmelee, D. E.; Kyle, P. R.; Kurz, M. D.; Marrero, S.

    2013-12-01

    Unraveling the timing of a volcano's most recent eruptions is crucial to understanding its present and future behavior. In this study, we use cosmogenic 3He and 36Cl in mineral separates (clinopyroxene and anorthoclase, respectively) to date the 10 most recent lava flows on Erebus volcano. Erebus is a 2,170-km3 active stratovolcano on Ross Island, Antarctica that is known for its persistent anorthoclase phonolite lava lake and frequent Strombolian eruptions. Previous anorthoclase 40Ar/39Ar ages from the 10 flows [1, 2] suggest they were erupted at roughly regular intervals between 17 and 0 ka. However, the uncertainties on the Ar ages are large (up to 39 %), and the likelihood of excess 40Ar in melt inclusions may skew the Ar ages older than eruption ages. The new cosmogenic ages provide new insights into Erebus eruption chronology. We used two different models to scale production rates: the Lal/Stone model [3] and the new Sato/Lifton model [4]. We find ~20-25 % younger ages with the Sato/Lifton model, attributable to different treatment of atmospheric pressure effects, solar modulation effects, and muogenic production rates in each model. 3He and 36Cl exposure ages of the same 10 flows range from 4.5 × 0.1 to 9.7 × 0.2 ka (Lal/Stone) or 3.5 × 0.1 to 7.5 × 0.2 ka (Sato/Lifton), significantly different than the Ar ages, with a much shorter eruption period. Surprisingly, three of the flows have exposure ages older than their Ar ages, despite the exposure ages being considered minimum ages of eruption and the Ar ages maxima. Concordance of the 3He and 36Cl ages measured in the same samples strengthens the validity of our results and implies that the 3He and 36Cl production rates [5] are well-calibrated for high latitude, high altitude sites and that the methodologies are robust. Regardless of which scaling model is used, the results yield a new understanding of the current eruptive phase of Erebus, particularly in documenting the short timespan over which the

  5. 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.

  6. In-Situ Cosmogenic 36Cl Production Rate Calibration from Basaltic Flows of Mount Etna (Sicily, 38° N)

    NASA Astrophysics Data System (ADS)

    Schimmelpfennig, I.; Benedetti, L.; Pik, R.; Burnard, P.; Blard, P. H.; Bourles, D.

    2007-12-01

    One of the CRONUS-EU goals is to provide high quality calibration sites from independently dated surfaces. Several previous studies have been conducted on 36Cl production rate calibration (e.g. Stone et al. 1996, Phillips et al. 2001), which, however, used different protocols and yielded 36Cl production rates with up to 40% discrepancies. The objectives of this study are 1- to understand the source of these discrepancies and 2- to calibrate 36Cl production rates from its target elements Ca and K. As a first step we focused on testing the chemical protocol by performing a sequential 36Cl extraction experiment on whole rock grains and Ca-rich plagioclase from the same sample. The sample was collected at Mt. Etna on a pahoehoe flow, which has a K-Ar fossil exposure time of (10±3) kyr. Cosmogenic 3He was also precisely measured within cogenetic olivine phenocrysts of this sample (Blard et al. 2005) and yields an exposure time of (10.4±1.5) kyr. Both, total Cl and 36Cl concentrations from the first dissolution steps are high, 5800 ppm (whole rock) and 450 ppm (plagioclase) Cl, and 107 - 106 atoms 36Cl/g of rock dissolved. After about 20% dissolution of the plagioclase sample, Cl is almost completely removed (1-3ppm) and 36Cl concentrations reach a plateau value of 2*105 atoms/g of rock. Using the Stone et al. (1996) and Evans et al. (1997) 36Cl production rates for the target elements Ca and K, respectively, this plateau concentration yields an exposure age which is in excellent agreement with K-Ar dating and cosmogenic 3He ages. On the contrary, in the whole rock sample total Cl concentrations remain high (>330ppm) resulting in a considerable 36Cl production from capture of low-energy neutrons by 35Cl, an additional and still not well-constrained 36Cl production mechanism. The resulting exposure ages from the whole rock are 35-45% higher than the independent 3He ages. For 36Cl production rate calibration from Ca, we will use separated Ca-rich plagioclase from various

  7. Groundwater and surface water flow to the Merced River, Yosemite Valley, California: 36Cl and Cl- evidence

    NASA Astrophysics Data System (ADS)

    Shaw, Glenn D.; Conklin, Martha H.; Nimz, Gregory J.; Liu, Fengjing

    2014-03-01

    Our current understanding of water fluxes and flow paths within the mountain block is limited, and improved understanding is necessary to assess hydrology more accurately above the mountain front. Source waters and the processes controlling their mixing were characterized in the Merced River basin within Yosemite National Park, California, using 36Cl and Cl-, supported by 222Rn, δ18O, δD, and streamflow data. Streams, snow, groundwater, and springs were sampled seasonally from July 2004 to October 2007. Three source water end-members were identified: (i) near surface runoff of recent meltwater containing bomb-pulse 36Cl (36ClBP), (ii) shallow, evapotranspired groundwater, and (iii) groundwater containing Cl- derived through extended rock interaction. Both groundwater end-members mix in Yosemite Valley and then later discharge to the Merced River. Near surface runoff dominates all stream hydrographs during snowmelt, whereas the two groundwater end-members become significantly more important during base flow. Tributaries consist of mixtures of the shallow evapotranspired groundwater and near surface runoff, whereas the Merced River is composed of the mixture of all source water end-members. Snow is not an obvious end-member, and elevated 36ClBP in the near surface runoff suggests that 36ClBP was retained efficiently, and is being slowly released as meltwater interacts with the soil. The use of 36Cl as a natural tracer is important in revealing the processes controlling streamflow generation in large montane catchments and the results will be helpful in configuring and calibrating hydrologic models.

  8. In situ 14C depth profile of subsurface vein quartz samples from Macraes Flat New Zealand

    NASA Astrophysics Data System (ADS)

    Kim, K. J.; Lal, D.; Englert, P. A. J.; Southon, J.

    2007-06-01

    We present results of measurements of cosmogenic in situ 14C produced in a quartz vein from Macraes Flat, East Otago, New Zealand, where concentrations of in situ produced 10Be and 26Al were previously studied by Kim and Englert [Earth Planet. Sci. Lett. 223 (2004) 113]. 14C was extracted from the quartz samples up to depths of 400 g cm-2 using a low temperature wet extraction method [D. Lal, A.J.T. Jull, Nucl. Instr. and Meth. B 92 (1994) 291]. Based on the results for 10Be and 26Al, we expected that the 14C activity in the samples would be at saturation levels, in equilibrium with erosion. The surface exposure age of this site was found to be about 25 000 years using 10Be and 26Al at the surface, with a surface erosion rate of at least 10-3 cm/y [K.J. Kim, P.A.J. Englert, Earth Planet. Sci. Lett. 223 (2004) 113]. The measured 14C activities were compared with those expected from spallation of Si and O in quartz by energetic neutrons and fast muons, and from capture of negative muons in O in quartz [B. Heisinger, A.J.T. Jull, D. Lal, P. Kubik, S. Ivy-Ochs, K. Knie, E. Nolte, Earth Planet. Sci. Lett. 200 (2002) 357; B. Heisinger, D. Lal, A.J.T. Jull, P. Kubik, S. Ivy-Ochs, S. Neumaier, K. Knie, V. Lazarev, E. Nolte, Earth Planet. Sci. Lett. 200 (2002) 345]. Surprisingly, we found that the 14C activities were significantly greater than those expected, by factors of 2 3, especially in samples of depths <200 g cm-2. We suspect that the excess 14C probably resulted from capture of thermal neutrons in nitrogen present in the fluid inclusions in quartz. This study shows that great care has to be taken in measurements of in situ 14C in quartz, especially in samples exposed near sea level and greater depths, where rates of spallation produced 14C are low.

  9. Pharmacokinetics of ruminally dosed sodium [36Cl]chlorate in beef cattle.

    PubMed

    Oliver, C E; Craigmill, A L; Caton, J S; Anderson, R C; Smith, D J

    2007-08-01

    The recently recognized potential of sodium chlorate as a possible preharvest food safety tool for pathogen reduction in meat animals has spurred interest in the pharmacokinetics of intraruminally dosed chlorate. Six Loala cattle were assigned (one heifer and one steer per treatment) to one of three intraruminal doses of radiolabeled sodium [36Cl]chlorate (21, 42, or 63 mg/kg body weight) administered in four equal aliquots over a 24-h period. Blood and serum were collected (29 samples in 48 h). Total radioactive residues were measured and the radioactive moieties were speciated. Chlorate appeared rapidly in blood and serum after dosing. For animals administered a dose of 42 or 63 mg/kg, the half-life of absorption was estimated at 0.6-0.9 h. Serum chlorate concentrations progressively increased with aliquot administration until peaking at 6-21 parts per million at 26 h. Between aliquot administrations, serum chlorate levels typically peaked in 3.5 h or less. The half-life of chlorate elimination ranged between 6.9 and 11 h, depending on the dose. Ultimately, absorption of chlorate removes it from its desired site of action, the lower gastrointestinal tract, thereby reducing its efficacy. Further research is needed to develop a chlorate formulation that will allow passage to the lower gastrointestinal tract.

  10. Tissue distribution, elimination, and metabolism of dietary sodium [36Cl]chlorate in beef cattle.

    PubMed

    Smith, David J; Anderson, Robin C; Ellig, Dee A; Larsen, Gerald L

    2005-05-18

    Two steers (approximately 195 kg) were each dosed with 62.5 or 130.6 mg/kg body weight sodium [36Cl]chlorate for three consecutive days. All excreta were collected during the dosing and 8 h withdrawal periods. The apparent radiochlorine absorption was 62-68% of the total dose with the major excretory route being urine. Parent chlorate was 65-100% of the urinary radiochlorine; chloride was the only other radiochlorine species present. Similarly, residues in edible tissues were composed of chloride and chlorate with chloride being the major radiolabeled species present. Chlorate represented 28-57% of the total radioactive residues in skeletal muscle; in liver, kidney, and adipose tissues, chlorate ion represented a smaller percentage of the total residues. Chlorate residues in the low dose steer were 26 ppm in kidney, 14 ppm in skeletal muscle, 2.0 ppm in adipose tissue, and 0.7 ppm in liver. These data indicate that sodium chlorate may be a viable preharvest food safety tool for use by the cattle industry.

  11. 26Al incorporation into the tissues of suckling rats through maternal milk

    NASA Astrophysics Data System (ADS)

    Yumoto, S.; Nagai, H.; Kobayashi, K.; Tada, W.; Horikawa, T.; Matsuzaki, H.

    2004-08-01

    Aluminium (Al) is highly neurotoxic and inhibits prenatal and postnatal development of the brain in humans and experimental animals. However, Al incorporation into the brain of sucklings through maternal milk has not yet been well clarified because Al lacks a suitable isotope for radioactive tracer experiments. Using 26Al as a tracer, we measured 26Al incorporation into the brain of suckling rats by accelerator mass spectrometry. Lactating rats were subcutaneously injected with 26AlCl3 from day 1 to day 20 postpartum. Suckling rats were weaned from day 21 postpartum. From day 5 to day 20 postpartum, the 26Al levels measured in the brain, liver, kidneys and bone of suckling rats increased significantly. After weaning, the amounts of 26Al in the liver and kidneys decreased remarkably. However, the 26Al amount in the brain had diminished only slightly up to 140 days after weaning.

  12. Did 26Al and impact-induced heating differentiate Mercury?

    NASA Astrophysics Data System (ADS)

    Bhatia, G. K.; Sahijpal, S.

    2017-02-01

    Numerical models dealing with the planetary scale differentiation of Mercury are presented with the short-lived nuclide, 26Al, as the major heat source along with the impact-induced heating during the accretion of planets. These two heat sources are considered to have caused differentiation of Mars, a planet with size comparable to Mercury. The chronological records and the thermal modeling of Mars indicate an early differentiation during the initial 1 million years (Ma) of the formation of the solar system. We theorize that in case Mercury also accreted over an identical time scale, the two heat sources could have differentiated the planets. Although unlike Mars there is no chronological record of Mercury's differentiation, the proposed mechanism is worth investigation. We demonstrate distinct viable scenarios for a wide range of planetary compositions that could have produced the internal structure of Mercury as deduced by the MESSENGER mission, with a metallic iron (Fe-Ni-FeS) core of radius 2000 km and a silicate mantle thickness of 400 km. The initial compositions were derived from the enstatite and CB (Bencubbin) chondrites that were formed in the reducing environments of the early solar system. We have also considered distinct planetary accretion scenarios to understand their influence on thermal processing. The majority of our models would require impact-induced mantle stripping of Mercury by hit and run mechanism with a protoplanet subsequent to its differentiation in order to produce the right size of mantle. However, this can be avoided if we increase the Fe-Ni-FeS contents to 71% by weight. Finally, the models presented here can be used to understand the differentiation of Mercury-like exoplanets and the planetary embryos of Venus and Earth.

  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. 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.

  15. 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.

  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. 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.

  18. 26Al incorporation into the brain of rat fetuses through the placental barrier and subsequent metabolism in postnatal development

    NASA Astrophysics Data System (ADS)

    Yumoto, Sakae; Nagai, Hisao; Kakimi, Shigeo; Matsuzaki, Hiroyuki

    2010-04-01

    Aluminium (Al) inhibits prenatal and postnatal development of the brain. We used 26Al as a tracer, and measured 26Al incorporation into rat fetuses through the placental barrier by accelerator mass spectrometry (AMS). From day 15 to day 18 of gestation, 26AlCl 3 was subcutaneously injected into pregnant rats. Considerable amounts of 26Al were measured in the tissues of newborn rats immediately after birth. The amounts of 26Al in the liver and kidneys decreased rapidly during postnatal development. However, approximately 15% of 26Al incorporated into the brain of fetuses remained in the brain of adult rats 730 days after birth.

  19. 26Al-26Mg systematics in chondrules from Kaba and Yamato 980145 CV3 carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Nagashima, Kazuhide; Krot, Alexander N.; Komatsu, Mutsumi

    2017-03-01

    We report the mineralogy, petrography, and in situ measured 26Al-26Mg systematics in chondrules from the least metamorphosed CV3 (Vigarano-type) chondrites, Kaba and Yamato (Y) 980145. Two Y 980145 chondrules measured show no resolvable excesses in 26Mg (26Mg∗), a decay product of a short-lived (t1/2 ∼0.7 Ma) radionuclide 26Al. Plagioclase in one of the chondrules is replaced by nepheline, indicative of thermal metamorphism. The lack of 26Mg∗ in the Y 980145 chondrules is most likely due to disturbance of their 26Al-26Mg systematics during the metamorphism. Although Kaba experienced extensive metasomatic alteration (<300 °C), it largely avoided subsequent thermal metamorphism, and the 26Al-26Mg systematics of its chondrules appear to be undisturbed. All eight Kaba chondrules measured show 26Mg∗, corresponding to the initial 26Al/27Al ratios [(26Al/27Al)0] ranging from (2.9 ± 1.7) × 10-6 to (6.3 ± 2.7) × 10-6. If CV parent asteroid accreted rapidly after chondrule formation, the inferred (26Al/27Al)0 ratios in Kaba chondrules provide an upper limit on 26Al available in this asteroid at the time of its accretion. The estimated initial abundance of 26Al in the CV asteroid is too low to melt it and contradicts the existence of a molten core in this body suggested from the paleomagnetic records of Allende [Carporzen et al. (2011) Magnetic evidence for a partially differentiated carbonaceous chondrite parent body. Proc. Natl. Acad. Sci. USA108, 6386-6389] and Kaba [Gattacceca et al. (2013) More evidence for a partially differentiated CV parent body from the meteorite Kaba. Lunar Planet. Sci.44, abstract#1721].

  20. Effect of sodium [36Cl]chlorate dose on total radioactive residues and residues of parent chlorate in growing swine.

    PubMed

    Smith, D J; Anderson, R C; Huwe, J K

    2006-11-01

    An experimental chlorate-based product has been shown to be efficacious in eliminating economically important, Gram-negative human pathogens in the gastrointestinal tracts of food animals. Prior to the commercial marketing of such a product, the magnitude and chemical nature of residues remaining in edible tissues must be determined. Thus, the objective of this study was to determine the tissue distribution and elimination of sodium [36Cl]chlorate in orally dosed swine. Three sets of pigs, each consisting of a barrow and a gilt, were orally dosed with a total of 20, 40, or 60 mg of sodium [36Cl]chlorate per kg body weight via the drinking water. Urine and feces were collected throughout the 30 h study. Twenty-four hours after the last exposure to [36Cl]chlorate, each pig was harvested and both edible and inedible tissues were collected. Urine and tissue samples were analyzed for total radioactive residues and for chlorate metabolites. Elimination of radioactivity in urine averaged 81.6, 83.7, and 83.9% of the total dose for the low, medium, and high doses, respectively. Fecal elimination of radioactivity averaged 1.1% of the dosed radiochlorine across all doses. Parent chlorate always represented greater than 97.4% of the urinary radiochlorine with the remaining radiochlorine being excreted as chloride ion. Chlorate represented 39-77% of fecal radioactivity, depending upon dose. Chlorate concentrations in edible tissues ranged from 0.01 to 0.49 ppm, with residues in liver and skeletal muscle generally lower than those in kidney and adipose tissue. Chlorate residues were concentrated in thyroid tissues (7.7-25.4 ppm) relative to edible tissues. No evidence for the presence of chlorite was observed in excreta or in tissues. Results of this study suggest that further development of chlorate as a preharvest food safety tool in swine merits consideration.

  1. Dating of prehistoric caves sediments and flints using 10Be and 26Al in quartz from Tabun Cave (Israel): Progress report

    NASA Astrophysics Data System (ADS)

    Boaretto, E.; Berkovits, D.; Hass, M.; Hui, S. K.; Kaufman, A.; Paul, M.; Weiner, S.

    2000-10-01

    There is an important need to develop additional dating methods beyond the 14C limit and independent of thermoluminescence (TL) and electron spin resonance (ESR). We propose to apply the method of burial dating to prehistoric sites using the decay of in situ produced radioisotopes 10Be and 26Al. The Tabun Cave, Mt. Carmel (Israel) has a sedimentary sequence which represents the type section for about the last 800,000 years in the Levant. The sediments in the cave are mainly of aeolian origin and are rich in quartz. Flint tools are also found in the sediments. Sediment samples and flint tools were selected from the same layer. Physical and chemical procedures to extract 10Be and 26Al atoms from the quartz fraction of the sediments and from the flint samples were developed, while measuring the natural Al levels as a monitor of the atmospheric component of the cosmogenic nuclides. AMS measurements were performed at the 14UD Pelletron Koffler Accelerator Laboratory, Weizmann Institute, and sensitivities of the order of 1×10 -14, in isotopic abundances for both 10Be and 26Al respectively (corresponding to ˜5 × 10 5 atoms) were obtained. First, measurements of a number of Tabun Cave sediment samples and flints show that 10Be and 26Al analyses have the potential for dating prehistoric cave sediments, provided problems relating to the presence of relatively large amounts of stable Al can be solved, as well as obtaining a better understanding of the burial history of the flints prior to being brought into the cave.

  2. Reconstructing the paleoseismic history of the Priene-Sazli Fault using 36Cl cosmogenic nuclide dating method, Western Anatolia, Turkey

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    The 300-km wide West Anatolian Extensional Province is one of the regions of intense seismic activity in the world within the Alpine-Himalayan belt. Deformation pattern in the area is controlled by three major E-W trending graben systems of Gediz, Küçük Menderes and Büyük Menderes which have been formed as a result of roughly N-S extensional tectonic regime since the early Miocene. These graben systems show evidences of surface faulting during the Pleistocene-Holocene and are geomorphologically characterized by well-exposed limestone normal fault scarps with a relief of tens of meters and well-preserved slickenlines. Since limestones are resistant to weathering, the limestone scarps can efficiently record several past earthquakes. Cosmogenic 36Cl is the only element to identify and date the rupture events. Each rupture causes exposure of previously buried section of the scarp to the surface. Accordingly, due to being well enough exposed to cosmic rays, accumulation of 36Cl accelerates during period of quiescence. Thus, distribution of measured 36Cl concentrations can be applied to investigate periods of seismic activity and inactivity and also to calculate the vertical displacement along the fault plane in association with each rupture. In this study, we focus on the Priene-Sazli Fault, located on the most western part of Büyük Menderes graben. Along the active fault zone, well exposed archaeological sites (e.g. Priene) have been discovered, where destructive historical earthquakes have left evidence of ancient damages in the historical period and during the 20th century. The Priene-Sazli Fault caused the July 16, 1955 Söke-Balat earthquake (M=6.8) with fault-plane solution indicating of normal southeast downthrow along with subsidiary dextral motion. We collected 117 samples from four continuous strips on the Priene-Sazli Fault to measure 36Cl concentrations. We used a new Matlab code to identify the significant ruptures and their timing. Our preliminary

  3. 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

  4. 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

  5. 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

  6. Understanding groundwater fracture-flow and near surface soil throughflow mixing within a mountain catchment using 36Cl/Cl, Yosemite National Park, California.

    NASA Astrophysics Data System (ADS)

    Shaw, G. D.; Conklin, M. H.; Nimz, G. J.

    2008-12-01

    In high elevation montane basins, there are typically limited observations to characterize watersheds. In this study we successfully use 36Cl and Cl- to characterize groundwater and near-surface water contributions to the upper Merced River and it's tributaries from Happy Isles to El Portal. Water fluxes typically consist of a variety of surface, near-surface and groundwater flow paths, which are complicated by faulted, folded, and fractured terrain. Surface water, snow, groundwater, and springs were sampled seasonally from July 2004 to October 2007. Snow 36Cl/Cl ratios are 3-30 times lower than in the Merced River water, but 36Cl/Cl ratios in the river increase 3-7 times from baseflow to the snowmelt season. This observation can be explained by characterizing endmembers in the watershed, and by determining how these endmembers vary temporally. Three endmembers mix in the catchment, and they include near-surface water with Cl- concentrations of 0.09 mg/L and 36Cl/Cl of 9976x10-15, groundwater primarily in contact with granitic rock with Cl- of 0.39 mg/L and 36Cl/Cl of 10711x10-15, and groundwater primarily in contact with metasedimentary rock with Cl- of 32.7 mg/L and 36Cl/Cl of 71x10-15. Metamorphic- dominated groundwater and granitic-dominated groundwater are further characterized by Ca2+/Cl- ratios (granitic-dominated groundwater is greater than 5, and metamorphic-dominated groundwater is less than 1). As the season transitions from snowmelt to baseflow, Cl- and 36Cl/Cl in surface water becomes more characteristic of both granitic and metamorphic-dominated groundwater depending on location. Plotting 1/Cl- verses 36Cl/Cl elucidates mixing lines which indicate that both groundwater endmembers have undergone evapotranspiration, but only the metamorphic-dominated groundwater shows evidence of incorporating significant amounts of rock chloride. The near-surface water is the dominant endmember during the snowmelt season and has similar Cl- concentrations as snow (~0

  7. {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.

  8. Harvesting the Decay Energy of 26-Al to Drive Lightning Discharge and Chondrule Formation

    NASA Astrophysics Data System (ADS)

    Johansen, A.; Okuzumi, S.

    2017-02-01

    We demonstrate that positrons released in the decay of 26-Al cause large-scale charging of dense pebble regions. The charge separation is neutralized by lightning discharge and this can lead to the formation of chondrules.

  9. Cross-sections for 36Cl from Ti at E p=35-150 MeV: Applications to in-situ exposure dating

    NASA Astrophysics Data System (ADS)

    Fink, David; Vogt, Stephan; Hotchkis, Michael

    2000-10-01

    We have measured the low-energy yield of 36Cl from Ti for proton energies from 35 to 150 MeV. Thin Ti foil irradiations were performed at the Harvard University Cyclotron Laboratory and 36Cl concentrations were determined using the ANTARES AMS facility at ANSTO. Cross-sections ranged smoothly with energy from 0.32±0.05 mb at 35 MeV to 5.3±0.4 mb at 150 MeV. Results for E<110 MeV are new, while the upper region from 110 to 150 MeV agrees well with overlapping data from other studies. The in-situ production rate for 36Cl from Ti at the earth's surface and high latitude based on this excitation function and calculations of Masarik and Reedy (normalised to the mean measured yield of 36Cl from Ca) is estimated at ˜(13±3) atoms 36Cl (g Ti yr) -1. We thus conclude that in Ti-rich, Ca-poor rocks or in typical basalts, 36Cl yield from Ti can amount to ˜5-10% of total. This is similar to the contribution from slow muon capture on 40Ca and in some cases, from thermal neutron capture on native Cl.

  10. 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.

  11. Evidence for Widespread 26Al in the Solar Nebula and Constraints for Nebula Time Scales

    PubMed

    Russell; Srinivasan; Huss; Wasserburg; MacPherson

    1996-08-09

    A search was made for 26Mg (26Mg*) from the decay of 26Al (half-life = 0.73 million years) in Al-rich objects from unequilibrated ordinary chondrites. Two Ca-Al-rich inclusions (CAIs) and two Al-rich chondrules (not CAIs) were found that contained 26Al when they formed. Internal isochrons for the CAIs yielded an initial 26Al/27Al ratio [(26Al/27Al)0] of 5 x 10(-5), indistinguishable from most CAIs in carbonaceous chondrites. This result shows that CAIs with this level of 26Al are present throughout the classes of chondrites and strengthens the notion that 26Al was widespread in the early solar system. The two Al-rich chondrules have lower 26Mg*, corresponding to a (26Al/27Al)0 ratio of approximately 9 x 10(-6). Five other Al-rich chondrules contain no resolvable 26Mg*. If chondrules and CAIs formed from an isotopically homogeneous reservoir, then the chondrules with 26Al must have formed or been last altered approximately2 million years after CAIs formed; the 26Mg*-free chondrules formed >1 to 3 million years later still. Because 26Mg*-containing and 26Mg*-free chondrules are both found in Chainpur, which was not heated to more than approximately400°C, it follows that parent body metamorphism cannot explain the absence of 26Mg* in some of these chondrules. Rather, its absence indicates that the lifetime of the solar nebula over which CAIs and chondrules formed extended over approximately5 million years.

  12. {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.

  13. 14C Analysis via Intracavity Optogalvanic Spectroscopy

    PubMed Central

    Murnick, Daniel; Dogru, Ozgur; Ilkmen, Erhan

    2010-01-01

    A new ultra sensitive laser-based analytical technique, intracavity optogalvanic spectroscopy (ICOGS), allowing extremely high sensitivity for detection of 14C-labeled carbon dioxide has recently been demonstrated. Capable of replacing accelerator mass spectrometers (AMS) for many applications, the technique quantifies zeptomoles of 14C in sub micromole CO2 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 14C/12C ratios have been obtained with theoretical limits much lower. Using a 15 W 14CO2 laser, a linear calibration with samples from 5 × 10−15 to >1.5 × 10−12 in 14C/12C ratios, as determined by AMS, was demonstrated. Calibration becomes non linear over larger concentration ranges due to interactions between CO2 and buffer gas, laser saturation effects and changes in equilibration time constants. The instrument is small (table top), low maintenance and can be coupled to GC or LC input. The method can also be applied to detection of other trace entities. Possible applications include microdosing studies in drug development, individualized sub therapeutic tests of drug metabolism, carbon dating and real time monitoring of atmospheric radiocarbon. PMID:20448803

  14. 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.

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

    PubMed

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

    2015-06-15

    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 (26)Al ((26)Al→(26)Mg; 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 (26)Al abundance [((26)Al/(27)Al)0] exists only for the oldest known solids, calcium aluminum-rich inclusions (CAIs) - the so-called canonical value. We have determined the (26)Al/(27)Al 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 ((26)Al/(27)Al)0 of [Formula: see text] 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 (54)Cr/(52)Cr ratios, most inner solar system materials likely accreted from material containing a similar (26)Al/(27)Al ratio as the APB precursor at the time of CAI formation. To satisfy the abundant evidence for widespread planetesimal differentiation, the subcanonical (26)Al 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

    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.

  17. 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.

  18. 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.

  19. 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

  20. 14C analysis via intracavity optogalvanic spectroscopy

    NASA Astrophysics Data System (ADS)

    Murnick, Daniel; Dogru, Ozgur; Ilkmen, Erhan

    2010-04-01

    A new ultra sensitive laser-based analytical technique, intracavity optogalvanic spectroscopy (ICOGS), allowing extremely high sensitivity for detection of 14C-labeled carbon dioxide has recently been demonstrated. Capable of replacing accelerator mass spectrometers (AMS) for many applications, the technique quantifies zeptomoles of 14C in sub micromole CO 2 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 -1514C/ 12C ratios have been obtained with theoretical limits much lower. Using a 15 W 14CO 2 laser, a linear calibration with samples from 5 × 10 -15 to >1.5 × 10 -12 in 14C/ 12C ratios, as determined by AMS, was demonstrated. Calibration becomes non-linear over larger concentration ranges due to interactions between CO 2 and buffer gas, laser saturation effects and changes in equilibration time constants. The instrument is small (table top), low maintenance and can be coupled to GC or LC input. The method can also be applied to detection of other trace entities. Possible applications include microdosing studies in drug development, individualized sub-therapeutic tests of drug metabolism, carbon dating and real time monitoring of atmospheric radiocarbon.

  1. Deglacial 14C plateau suites recalibrated by Suigetsu atmospheric 14C record - Revised 14C reservoir ages from three ocean basins corroborate extreme surface water variations

    NASA Astrophysics Data System (ADS)

    Sarnthein, M.; Balmer, S.; Grootes, P. M.

    2013-12-01

    Radiocarbon (14C) reservoir/ventilation ages (Δ14C) provide unique insights into the dynamics of ocean water masses over LGM and deglacial times. The 14C plateau-tuning technique enables us to derive both an absolute chronology for marine sediment records and a high-resolution record of changing Δ14C values for deglacial surface and deep waters (Sarnthein et al., 2007; AGU Monogr. 173, 175). We designate as 14C plateau a sediment section in the age-depth profile with several almost constant planktic 14C ages - variation less than ×100 to ×300 yr - which form a plateau-shaped scatter band that extends over ~5 to 50 and up to 200 cm in sediment cores with sedimentation rates of >10 cm/ky. Previously, a suite of >15 plateau boundary ages were calibrated to a joint reference record of U/Th-dated 14C time series measured on coral samples, the Cariaco sediment record, and speleothems (Fairbanks et al., 2005, QSR 24; Hughen et al., 2006, QSR 25; Beck et al., 2001, Science 292). We now used the varve-counted atmospheric 14C record of Lake Suigetsu (Ramsey et al., 2012, Science 338, 370) to recalibrate the boundary ages and average ages of 14C plateaus and apply the amended plateau-tuning technique to a dozen Δ14C records from the Atlantic and Indo-Pacific. Main results are: (1) The Suigetsu atmospheric 14C record reflects all 14C plateaus, their internal structures and relative length previously identified, but implies a rise in the average plateau age by <200 14C yr during the LGM, >700 yr at its end, and <200 yr in the Bølling-Allerød. (2) Based on different 14C ages of coeval atmospheric and planktic 14C plateaus surface water Δ14C may have temporarily dropped to an equivalent of 200 yr in low-latitude stratified waters, such as off northwestern South America, and in turn reached values corresponding to an age difference of >2500 14C yr in stratified subpolar regions and upwelled waters such as in the South China Sea, values that differ significantly from a

  2. 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

  3. Phase Polymorphism, Molecular Motions and Structural Changes in [Cr(NH3)6](ClO4)3

    NASA Astrophysics Data System (ADS)

    Mikuli, Edward; Górska, Natalia; Wróbel, Stanisław; Ściesińskic, Jacek; Ściesińska, Ewa

    2007-04-01

    A phase transition in [Cr(NH3)6](ClO4)3 at Thc = 293.5 K (on heating) and Tcc = 293.0 K (on cooling) was determined by differential scanning calorimetry. The temperature dependences of the full width at half maximum of the bands connected with ρr(NH3)F1u and δd(ClO)E modes suggest that the discovered phase transition is not connected with drastic changes in the speed of reorientational motions of the NH3 ligands nor the ClO4 - anions. Temperature dependence of the FT-FIR spectra and the diffraction patterns show that the discovered phase transition is caused by a change in the crystal structure.

  4. {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.

  5. 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.

  6. Can cosmogenic nuclides (36Cl) unravel the timing of dislocation of tsunami blocks on Bonaire (Leeward Antilles)?

    NASA Astrophysics Data System (ADS)

    Engel, Max; Rixhon, Gilles; Brückner, Helmut; May, S. Matthias; Binnie, Steve; Dunai, Tibor J.

    2013-04-01

    On Bonaire (Leeward Antilles) and rocky coasts worldwide, high-energy wave events (tsunamis, storms) dislocate coarse-clast deposits (Engel and May, 2012). Using these onshore blocks and boulders to derive ages for the most powerful events on millennial scales is still a major challenge. We apply terrestrial cosmogenic nuclides (TCN), in particular 36Cl, in case of the largest blocks in order to directly date the transport event(s), i.e. the inferred tsunami(s). This dating method has hitherto been disregarded in the coastal environment, particularly in the context of block transport. The following characteristics of the blocks are fundamental for the success of the presented dating approach: (1) due to the lithology (aragonite, calcite), concentration measurements of 36Cl are performed; (2) only large and thick boulders and blocks (>50 t, >2 m thickness) for which tsunami transport was inferred (Engel and May, 2012) were sampled; (3) since the boulders stem from the edge of the coral reef platform, they had been exposed to cosmic radiation prior to the transport event(s) and had already accumulated a certain amount of TCN. To avoid this problem of inheritance, we only sampled the thickest clasts, and those having experienced a 180° overturn during transport; thus, having exposed a "blank" side to cosmic rays only since the event. The complete overturn is attested by the presence of inactive rock pools in upside-down position and bioerosive notches. Engel, M., and May, S. M.: Bonaire's boulder fields revisited: Evidence for Holocene tsunami impact on the Leeward Antilles, Quat. Sci. Rev., 54, 126-141, 2012.

  7. Effect of sodium [36Cl]chlorate dose on total radioactive residues and residues of parent chlorate in beef cattle.

    PubMed

    Smith, D J; Oliver, C E; Caton, J S; Anderson, R C

    2005-09-07

    The objectives of this study were to determine total radioactive residues and chlorate residues in edible tissues of cattle administered at three levels of sodium [36Cl]chlorate over a 24-h period and slaughtered after a 24-h withdrawal period. Three sets of cattle, each consisting of a heifer and a steer, were intraruminally dosed with a total of 21, 42, or 63 mg of sodium [36Cl]chlorate/kg of body weight. To simulate a 24-h exposure, equal aliquots of the respective doses were administered to each animal at 0, 8, 16, and 24 h. Urine and feces were collected in 12-h increments for the duration of the 48-h study. At 24 h after the last chlorate exposure, cattle were slaughtered and edible tissues were collected. Urine and tissue samples were analyzed for total radioactive residues and for metabolites. Elimination of radioactivity in urine and feces equaled 20, 33, and 48% of the total dose for the low, medium, and high doses, respectively. Chlorate and chloride were the only radioactive chlorine species present in urine; the fraction of chlorate present as a percentage of the total urine radioactivity decreased with time regardless of the dose. Chloride was the major radioactive residue present in edible tissues, comprising over 98% of the tissue radioactivity for all animals. Chlorate concentrations in edible tissues ranged from nondetectable to an average of 0.41 ppm in skeletal muscle of the high-dosed animals. No evidence for the presence of chlorite was observed in any tissue. Results of this study suggest that further development of chlorate as a preharvest food safety tool merits consideration.

  8. 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

  9. Distribution of 26Al in the CR chondrite chondrule-forming region of the protoplanetary disk

    NASA Astrophysics Data System (ADS)

    Schrader, Devin L.; Nagashima, Kazuhide; Krot, Alexander N.; Ogliore, Ryan C.; Yin, Qing-Zhu; Amelin, Yuri; Stirling, Claudine H.; Kaltenbach, Angela

    2017-03-01

    We report on the mineralogy, petrography, and in situ measured oxygen- and magnesium-isotope compositions of eight porphyritic chondrules (seven FeO-poor and one FeO-rich) from the Renazzo-like carbonaceous (CR) chondrites Graves Nunataks 95229, Grosvenor Mountains 03116, Pecora Escarpment 91082, and Queen Alexandra Range 99177, which experienced minor aqueous alteration and very mild thermal metamorphism. We find no evidence that these processes modified the oxygen- or Al-Mg isotope systematics of chondrules in these meteorites. Olivine, low-Ca pyroxene, and plagioclase within an individual chondrule have similar O-isotope compositions, suggesting crystallization from isotopically uniform melts. The only exceptions are relict grains in two of the chondrules; these grains are 16O-enriched relative to phenocrysts of the host chondrules. Only the FeO-rich chondrule shows a resolvable excesses of 26Mg, corresponding to an inferred initial 26Al/27Al ratio [(26Al/27Al)0] of (2.5 ± 1.6) × 10-6 (±2SE). Combining these results with the previously reported Al-Mg isotope systematics of CR chondrules (Nagashima et al., 2014, Geochem. J. 48, 561), 7 of 22 chondrules (32%) measured show resolvable excesses of 26Mg; the presence of excess 26Mg does not correlate with the FeO content of chondrule silicates. In contrast, virtually all chondrules in weakly metamorphosed (petrologic type 3.0-3.1) unequilibrated ordinary chondrites (UOCs), Ornans-like carbonaceous (CO) chondrites, and the ungrouped carbonaceous chondrite Acfer 094 show resolvable excesses of 26Mg. The inferred (26Al/27Al)0 in CR chondrules with resolvable excesses of 26Mg range from (1.0 ± 0.4) × 10-6 to (6.3 ± 0.9) × 10-6, which is typically lower than (26Al/27Al)0 in the majority of chondrules from UOCs, COs, and Acfer 094. Based on the inferred (26Al/27Al)0, three populations of CR chondrules are recognized; the population characterized by low (26Al/27Al)0 (<3 × 10-6) is dominant. There are no noticeable

  10. THE GALACTIC {sup 26}AL EMISSION MAP AS REVEALED BY INTEGRAL SPI

    SciTech Connect

    Bouchet, Laurent; Jourdain, Elisabeth; Roques, Jean-Pierre

    2015-03-10

    Diffuse emission is often challenging since it is undetectable by most instruments, which are generally dedicated to point-source studies. The {sup 26}Al emission is a good illustration: the only available {sup 26}Al map to date has been released, more than 15 yr ago, thanks to the COMPTEL instrument. However, at the present time, the SPI spectrometer aboard the International Gamma-Ray Astrophysics Laboratory mission offers a unique opportunity to enrich this first result. In this paper, 2 × 10{sup 8} s of data accumulated between 2003 and 2013 are used to perform a dedicated analysis, aiming to deeply investigate the spatial morphology of the {sup 26}Al emission. The data are first compared with several sky maps based on observations at various wavelengths to model the {sup 26}Al distribution throughout the Galaxy. For most of the distribution models, the inner Galaxy flux is compatible with a value of 3.3 × 10{sup −4} photons cm{sup −2} s{sup −1}, while the preferred template maps correspond to young stellar components such as core-collapse supernovae (SNe), Wolf–Rayet stars, and massive AGB stars. To get more details about this emission, an image reconstruction is performed using an algorithm based on the maximum-entropy method. In addition to the inner Galaxy emission, several excesses suggest that some sites of emission are linked to the spiral arm structure. Lastly, an estimation of the {sup 60}Fe line flux, assuming a spatial distribution similar to {sup 26}Al line emission, results in a {sup 60}Fe-to-{sup 26}Al ratio around 0.14, which agrees with the most recent studies and with the SN explosion model predictions.

  11. The Galactic 26Al Emission Map as Revealed by INTEGRAL SPI

    NASA Astrophysics Data System (ADS)

    Bouchet, Laurent; Jourdain, Elisabeth; Roques, Jean-Pierre

    2015-03-01

    Diffuse emission is often challenging since it is undetectable by most instruments, which are generally dedicated to point-source studies. The 26Al emission is a good illustration: the only available 26Al map to date has been released, more than 15 yr ago, thanks to the COMPTEL instrument. However, at the present time, the SPI spectrometer aboard the International Gamma-Ray Astrophysics Laboratory mission offers a unique opportunity to enrich this first result. In this paper, 2 × 108 s of data accumulated between 2003 and 2013 are used to perform a dedicated analysis, aiming to deeply investigate the spatial morphology of the 26Al emission. The data are first compared with several sky maps based on observations at various wavelengths to model the 26Al distribution throughout the Galaxy. For most of the distribution models, the inner Galaxy flux is compatible with a value of 3.3 × 10-4 photons cm-2 s-1, while the preferred template maps correspond to young stellar components such as core-collapse supernovae (SNe), Wolf-Rayet stars, and massive AGB stars. To get more details about this emission, an image reconstruction is performed using an algorithm based on the maximum-entropy method. In addition to the inner Galaxy emission, several excesses suggest that some sites of emission are linked to the spiral arm structure. Lastly, an estimation of the 60Fe line flux, assuming a spatial distribution similar to 26Al line emission, results in a 60Fe-to-26Al ratio around 0.14, which agrees with the most recent studies and with the SN explosion model predictions.

  12. Revisiting 26Al-26Mg systematics of plagioclase in H4 chondrites

    NASA Astrophysics Data System (ADS)

    Telus, M.; Huss, G. R.; Nagashima, K.; Ogliore, R. C.

    2014-06-01

    Zinner and Göpel found clear evidence for the former presence of 26Al in the H4 chondrites Ste. Marguerite and Forest Vale. They assumed that the 26Al-26Mg systematics of these chondrites date "metamorphic cooling of the H4 parent body." Plagioclase in these chondrites can have very high Al/Mg ratios and low Mg concentrations, making these ion probe analyses susceptible to ratio bias, which is inversely proportional to the number of counts of the denominator isotope (Ogliore et al.). Zinner and Göpel used the mean of the ratios to calculate the isotope ratios, which exacerbates this problem. We analyzed the Al/Mg ratios and Mg isotopic compositions of plagioclase grains in thin sections of Ste. Marguerite, Forest Vale, Beaver Creek, and Sena to evaluate the possible influence of ratio bias on the published initial 26Al/27Al ratios for these meteorites. We calculated the isotope ratios using total counts, a less biased method of calculating isotope ratios. The results from our analyses are consistent with those from Zinner and Göpel, indicating that ratio bias does not significantly affect 26Al-26Mg results for plagioclase in these chondrites. Ste. Marguerite has a clear isochron with an initial 26Al/27Al ratio indicating that it cooled to below 450 °C 5.2 ± 0.2 Myr after CAIs. The isochrons for Forest Vale and Beaver Creek also show clear evidence that 26Al was alive when they cooled, but the initial 26Al/27Al ratios are not well constrained. Sena does not show evidence that 26Al was alive when it cooled to below the Al-Mg closure temperature. Given that metallographic cooling rates for Ste. Marguerite, Forest Vale, and Beaver Creek are atypical (>5000 °C/Myr at 500 °C) compared with most H4s, including Sena, which have cooling rates of 10-50 °C/Myr at 500 °C (Scott et al.), we conclude that the Al-Mg systematics for Ste. Marguerite, Forest Vale, and Beaver Creek are the result of impact excavation of these chondrites and cooling at the surface of the

  13. 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/2011NIMPB.269.3171M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011NIMPB.269.3171M"><span>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://adsabs.harvard.edu/abs/2016GeCoA.192..279H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.192..279H"><span>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/2013M%26PSA..76.5085P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013M%26PSA..76.5085P"><span>Heterogeneity of Mg Isotopes and Variable ^<span class="hlt">26</span><span class="hlt">Al</span>/^27Al Ratio in FUN CAIs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Park, C.; Nagashima, K.; Hutcheon, I. D.; Wasserburg, G. J.; Papanastassiou, D. A.; Davis, A. M.; Huss, G. R.; Krot, A. N.</p> <p>2013-09-01</p> <p>We report high-precision Mg-isotope data of individual minerals from the Axtell 2271, BG82DH8, EK1-4-1, C1, TE, and CG14 FUN CAIs, which shows variations in both Mg-isotope ratio and ^<span class="hlt">26</span><span class="hlt">Al</span>/^27Al ratio.</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>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>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.osti.gov/scitech/biblio/5417245','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5417245"><span>Distribution of labeled products from (1-/sup <span class="hlt">14</span>/<span class="hlt">C</span>), (U-/sup <span class="hlt">14</span>/<span class="hlt">C</span>) and (16-/sup <span class="hlt">14</span>/<span class="hlt">C</span>)-palmitate in isolated rat hepatocytes and liver mitochondria</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Chatzidakis, C.; Otto, D.A.</p> <p>1986-05-01</p> <p>Fatty acids (FA) labeled in different carbon positions are used to study the distribution of labeled oxidation products. With rat hepatocytes (Hep) the authors observed significant differences in the distribution of label into products from (1-/sup <span class="hlt">14</span>/<span class="hlt">C</span>) and (U-/sup <span class="hlt">14</span>/<span class="hlt">C</span>)-palmitate (P). The total recovery of label in products (/sup 14/CO/sub 2/ + acid soluble fraction (ASF)) was identical between the two labeled FA. However, /sup 14/CO/sub 2/ production from (U-/sup <span class="hlt">14</span>/<span class="hlt">C</span>)-P was only 40% of that from (1-/sup <span class="hlt">14</span>/<span class="hlt">C</span>)-P. A recent report showed that approximately = 95% of succinate (Suc) utilized by Hep does not complete one full turn through the citric acid cycle. The authors observed that /sup 14/CO/sub 2/ evolution from (2,3-/sup <span class="hlt">14</span>/<span class="hlt">C</span>)-Suc was approximately = 9% of that from (1,4-/sup <span class="hlt">14</span>/<span class="hlt">C</span>)-Suc, indicating that the differences in label distribution between (1-/sup <span class="hlt">14</span>/<span class="hlt">C</span>) and (U-/sup <span class="hlt">14</span>/<span class="hlt">C</span>)-P are partially due to less /sup 14/CO/sub 2/ production from label in the even carbon positions of the FA with consequently more label remaining in the ASF. The /sup 14/CO/sub 2/ production from (16-/sup <span class="hlt">14</span>/<span class="hlt">C</span>)-P was only 4% of that from (1-/sup <span class="hlt">14</span>/<span class="hlt">C</span>)-P a value less than expected from the Suc experiments. Ketone bodies (KB) comprised 78% of total labeled products from (16-/sup <span class="hlt">14</span>/<span class="hlt">C</span>)-P as compared to 28% from (1-/sup <span class="hlt">14</span>/<span class="hlt">C</span>)-P and 41% from (U-/sup <span class="hlt">14</span>/<span class="hlt">C</span>)-P, giving support to the previously reported preferential use of the omega-C/sub 2/ unit for KB synthesis without entry into the acetyl-CoA pool. Studies with isolated rat liver mitochondria gave results similar to those with Hep, indicating minimal involvement of perioxisomal ..beta..-oxidation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17279768','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17279768"><span>Tissue residues, metabolism, and excretion of radiolabeled sodium chlorate (Na[<span class="hlt">36</span><span class="hlt">Cl</span>]O3) 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>Hakk, Heldur; Smith, David J; Shappell, Nancy W</p> <p>2007-03-07</p> <p>A novel preharvest technology that reduces certain pathogenic bacteria in the gastrointestinal tracts of food animals involves feeding an experimental sodium chlorate-containing product (ECP) to animals 24-72 h prior to slaughter. To determine the metabolism and disposition of the active ingredient in ECP, four male Sprague-Dawley (approximately 350 g) rats received a single oral dose of sodium [<span class="hlt">36</span><span class="hlt">Cl</span>]chlorate (3.0 mg/kg body weight). Urine, feces, and respired air were collected for 72 h. Radiochlorine absorption was 88-95% of the administered dose, and the major excretory route was the urine. Parent chlorate was the major species of radiochlorine present in urine at 6 h (approximately 98%) but declined sharply by 48 h (approximately 10%); chloride was the only other species of radiochlorine detected. Except for carcass remains (4.6% of dose), skin (3.2%), and gastrointestinal tract (1.3%), remaining tissues contained relatively low quantities of radioactivity, and >98% of radiochlorine remaining in the liver, kidney, and skeletal muscle was chloride. Chlorite instability was demonstrated in rat urine and bovine urine. The previously reported presence of chlorite in excreta of chlorate-dosed rats was shown to be an artifact of the analytical methods employed. Results from this study indicate that chlorate is rapidly absorbed and reduced to chloride, but not chlorite, in rats.</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('http://www.osti.gov/scitech/servlets/purl/277041','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/277041"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/6412727','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/6412727"><span>Pharmacokinetics of <span class="hlt">14</span><span class="hlt">C</span> CDP-choline.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dinsdale, J R; Griffiths, G K; Rowlands, C; Castelló, J; Ortiz, J A; Maddock, J; Aylward, M</p> <p>1983-01-01</p> <p>The absorption, metabolism and excretion of cytidine diphosphate choline (CDP-choline, citicoline, Somazina) were investigated in six adult healthy subjects after a single oral dose of 300 mg of the <span class="hlt">14</span><span class="hlt">C</span>-labelled compound. The compound was well tolerated by the subjects. Absorption was virtually complete with less than 1% of the dose being found in the faeces during the 5-day collection period. Two peaks were found in the plasma radioactivity time profile: the first at 1 h, and a second larger peak at 24 h post-dose. Elimination of the ingested dose occurred via respiratory CO2 and through urinary excretion; the former predominating, and both routes exhibited biphasic patterns characterized by an early phase followed by slower decline. It is postulated that in the healthy human subject CDP-choline is metabolized in the gut wall and in the liver; the products arising from the compound's extensive hepatic metabolism being subsequently available for diverse biosynthetic pathways, tissue metabolism, and excretion.</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>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/1997NIMPB.123..259K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997NIMPB.123..259K"><span>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('http://adsabs.harvard.edu/abs/2016GeCoA.176..295L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.176..295L"><span>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>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://pubs.er.usgs.gov/publication/70157344','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70157344"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/27791367','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27791367"><span>Distribution, Identification, and Quantification of Residues after Treatment of Ready-To-Eat Salami with (<span class="hlt">36</span>)<span class="hlt">Cl</span>-Labeled or Nonlabeled Chlorine Dioxide Gas.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Smith, David J; Giddings, J Michael; Herges, Grant R; Ernst, William</p> <p>2016-11-09</p> <p>When ready-to-eat salami was treated in a closed system with (<span class="hlt">36</span>)<span class="hlt">Cl</span>-labeled ClO2 (5.5 mg/100 g of salami), essentially all radioactivity was deposited onto the salami. Administered (<span class="hlt">36</span>)<span class="hlt">Cl</span>O2 was converted to (<span class="hlt">36</span>)<span class="hlt">Cl</span>-chloride ion (>97%), trace levels of chlorate (<2%), and detectable levels of chlorite. In residue studies conducted with nonlabeled ClO2, sodium perchlorate residues (LOQ, 4 ng/g) were not formed when reactions were protected from light. Sodium chlorate residues were present in control (39.2 ± 4.8 ng/g) and chlorine dioxide treated (128 ± 31.2 ng/g) salami. If sanitation occurred under conditions of illumination, detectable levels (3.7 ± 1.5 ng/g) of perchlorate were formed along with greater quantities of sodium chlorate (183.6 ± 75.4 ng/g). Collectively, these data suggest that ClO2 is chemically reduced by salami and that slow-release formulations might be appropriate for applications involving the sanitation of ready-to-eat meat products.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/126696','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/126696"><span>The use of groundwater tracers, including {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>, {delta}{sup 18}O, and {delta}{sup 2}JH, in the study fo the Magothy aquifer, Maryland</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bond, C.A.; Mignerey, A.C.; Helz, G.R.</p> <p>1995-12-01</p> <p>The recent conclusion of a study of groundwater from the Magothy Formation, Maryland allows for an examination of processes occurring in this aquifer system. Water samples were gathered from a wide area along flow paths estimated from hydrological parameters and analyzed for the major cations and anions, nutrients, and {sup 87}Sr/{sup 86}Sr ratios, in addition to {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>, {delta}{sup 18}O, and {delta}{sup 2}H. Also, three samples that contained anomalously high {sup <span class="hlt">36</span>}<span class="hlt">Cl</span>/Cl ratios were analyzed for {sup 3}H in an attempt to determine possible sources for those readings. A comparison of the results of this study to those of a previous study conducted by this group of the overlying Aquia Aquifer will also be given. The potential of inter-aquifer mixing between the two systems in some areas and of matching {sup <span class="hlt">36</span>}<span class="hlt">Cl</span> and Cl{sup -} values to sea level rise and fall will be discussed.</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>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://adsabs.harvard.edu/abs/2013EGUGA..15.3563Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.3563Z"><span>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('http://adsabs.harvard.edu/abs/1996LPI....27.1257S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996LPI....27.1257S"><span>New Evidence for <span class="hlt">26</span><span class="hlt">Al</span> in CAI and Chondrules from Type 3 Ordinary Chondrites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Srinivasan, G.; Russell, S. S.; MacPherson, G. J.; Huss, G. R.; Wasserburg, G. J.</p> <p>1996-03-01</p> <p>We have known since 1976 that 26A1 (tl/2 = 7.2 x 105 yrs) was alive in the early solar system, at a level of (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)o z 5 x 10-5 in calcium-aluminum inclusions (CAI). However, several outstanding questions remain. Little evidence for 26A1 has been found in other chondritic material, and none has been found in differentiated meteorites. These results might imply that 26A1 was heterogeneously distributed in the nebula or by mineralogic site in nebular dust, or they might reflect differences in time of formation. There are strict limitations on finding evidence of 26A1 in normal chondrules with bulk Al/Mg ~ 0.1, since even quenched, perfectly preserved, late-stage glasses would have low Al/Mg. Primary plagioclase crystals provide the only possibility, but these only crystallize rarely in melts within the compositional range of normal chondrules. Also, metamorphism can erase the evidence in high-AI/Mg phases. To address these issues, we have conducted a search for chondrules and CAI with high-Al/Mg phases suitable for ion-probe measurement in type 3 ordinary chondrites. Previous work has revealed evidence for <span class="hlt">26</span><span class="hlt">Al</span> in a plagioclase bearing, olivine-pyroxene class from Semarkona (LL3.0; (<span class="hlt">26</span><span class="hlt">Al</span>/27Al)o = 7.7+/-2.1 x 10-6)), a plagioclase-rich object from Bovedy (L3.7?; 2.5+/-1.2 x 10-7), in separated plagioclase from St. Marguerite (H4; 2.0+/-0.6 x 10-7), an isolated hibonite grain from Dhajala (H3.8; 8.4+0.5 x 10-6), and in Al2O3 and hibonite grains ((<span class="hlt">26</span><span class="hlt">Al</span>/27Al)o = 2-5 x 10-5; [GRH, unpublished]) from acid residues of Semarkona, Bishunpur (LL3.1), and Krymka (LL3.1). We have identified and measured Al-Mg isotope systematics in two CAI and seven chondrules from ordinary chondrites of low metamorphic grade and have found clear evidence for 26A1 in both CAI and in two chondrules.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21300663','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21300663"><span>{sup <span class="hlt">26</span>}<span class="hlt">Al</span> AND THE FORMATION OF THE SOLAR SYSTEM FROM A MOLECULAR CLOUD CONTAMINATED BY WOLF-RAYET WINDS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gaidos, Eric; Krot, Alexander N.; Williams, Jonathan P.; Raymond, Sean N. E-mail: sasha@higp.hawaii.edu E-mail: sean.raymond@colorado.edu</p> <p>2009-05-10</p> <p>In agreement with previous work, we show that the presence of the short-lived radionuclide (SLR) {sup <span class="hlt">26</span>}<span class="hlt">Al</span> in the early solar system was unlikely (less than 2% a priori probability) to be the result of direct introduction of supernova (SN) ejecta into the gaseous disk during the Class II stage of protosolar evolution. We also show that Bondi-Hoyle accretion of any contaminated residual gas from the Sun's natal star cluster contributed negligible {sup <span class="hlt">26</span>}<span class="hlt">Al</span> to the primordial solar system. Our calculations are consistent with the absence of the oxygen isotopic signature expected with any late introduction of SN ejecta into the protoplanetary disk. Instead, the presence of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> in the oldest solar system solids (calcium-aluminum-rich inclusions (CAIs)) and its apparent uniform distribution with the inferred canonical {sup <span class="hlt">26</span>}<span class="hlt">Al</span>/{sup 27}Al ratio of (4.5-5) x 10{sup -5} support the inheritance of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> from the Sun's parent giant molecular cloud. We propose that this radionuclide originated in a prior generation of massive stars that formed in the same molecular cloud and contaminated that cloud by Wolf-Rayet winds. We calculated the Galactic distribution of {sup <span class="hlt">26</span>}<span class="hlt">Al</span>/{sup 27}Al ratios that arise from such contamination using the established embedded cluster mass and stellar initial mass functions, published nucleosynthetic yields from the winds of massive stars, and by assuming rapid and uniform mixing into the cloud. Although our model predicts that the majority of stellar systems contain no {sup <span class="hlt">26</span>}<span class="hlt">Al</span> from massive stars, and that the a priori probability that the {sup <span class="hlt">26</span>}<span class="hlt">Al</span>/{sup 27}Al ratio will reach or exceed the canonical solar system value is only {approx}6%, the maximum in the distribution of nonzero values is close to the canonical {sup <span class="hlt">26</span>}<span class="hlt">Al</span>/{sup 27}Al ratio. We find that the Sun most likely formed 4-5 million years (Myr) after the massive stars that were the source of {sup <span class="hlt">26</span>}<span class="hlt">Al</span>. Furthermore, our model can explain the initial solar system</p> </li> <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><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('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>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> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25459713','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25459713"><span>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>2015-02-05</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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007JGRA..11210106W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007JGRA..11210106W"><span>Production of the cosmogenic isotopes 3H, 7Be, 10Be, and <span class="hlt">36</span><span class="hlt">Cl</span> in the Earth's atmosphere by solar and galactic cosmic rays</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Webber, W. R.; Higbie, P. R.; McCracken, K. G.</p> <p>2007-10-01</p> <p>In a follow-up study to the earlier work of Webber and Higbie (2003) on 10Be production in the Earth's atmosphere by cosmic rays, we have calculated the atmospheric production of the cosmogenic isotopes 3H, 7Be, 10Be, and <span class="hlt">36</span><span class="hlt">Cl</span> using the FLUKA Monte Carlo code. This new calculation of atmospheric yields of these isotopes is based on 107 vertically incident protons at each of 24 logarithmically spaced energies from 10 MeV to 10 GeV, 102 times the number used in the earlier calculation, along with the latest cross sections. This permits a study of the production due to solar cosmic rays as well as galactic cosmic rays at lower energies where isotope production is a very sensitive function of energy. Solar cosmic ray spectra are reevaluated for all of the major events occurring since 1956. In terms of yearly production of 10Be, only the February 1956 solar event makes a major contribution. For <span class="hlt">36</span><span class="hlt">Cl</span> these yearly SCR production contributions are 2-5 times larger depending on the solar cosmic ray energy spectra. We have determined the yearly production of 10Be, <span class="hlt">36</span><span class="hlt">Cl</span>, and other cosmogenic isotopes above 65° geomagnetic latitude for the time period 1940-2006 covering six solar 11-year (a) cycles. The average peak-to-peak 11-a amplitude of this yearly production is 1.77. The effects of latitudinal mixing alter these direct polar production values considerably, giving an average peak-to-peak 11-a amplitude of 1.48 for the global average production.</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>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/2015A%26A...578A.113K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015A%26A...578A.113K"><span><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/2013NIMPB.294..252G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013NIMPB.294..252G"><span>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> </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('http://adsabs.harvard.edu/abs/2004NIMPB.223..770Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004NIMPB.223..770Z"><span>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('https://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="https://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>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.; ...</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('https://www.osti.gov/scitech/biblio/5374374','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5374374"><span>/sup <span class="hlt">14</span>/<span class="hlt">C</span> distribution in the Atlantic Ocean</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Stuiver, M.</p> <p>1980-05-20</p> <p>The amount of /sup <span class="hlt">14</span>/<span class="hlt">C</span> produced by nuclear bomb testing that entered the Atlantic Ocean by late 1972 was 1.71 x 10/sup -8/ ..mu..mol/cm/sup 2/ of ocean surface area for the west Atlantic (36/sup 0/S-45/sup 0/N) and 1.18 x 10/sup -8/ ..mu..mol/cm/sup 2/ for the east Atlantic (50/sup 0/S-28/sup 0/N) Geochemical Ocean Sections Study stations. There are strong latitudinal differences in the integrated amount of bomb /sup <span class="hlt">14</span>/<span class="hlt">C</span> content in Atlantic waters. Bomb-produced /sup <span class="hlt">14</span>/<span class="hlt">C</span> is mostly encountered near the center of the large mid-latitude gyres, whereas the equatorial region has a lower /sup <span class="hlt">14</span>/<span class="hlt">C</span> inventory. The average ocean wide vertical distribution of bomb /sup <span class="hlt">14</span>/<span class="hlt">C</span> in the Atlantic can be explained by a vertical eddy diffusion coefficient of 4.0 cm/sup 2//s in the surface mixed layer plus thermocline gyre reservoirs. The average /sup <span class="hlt">14</span>/<span class="hlt">C</span> activity per unit area measured in the Atlantic yields an atmosphere-ocean CO/sub 2/ exchange rate of 23 mol/m/sup 2/ yr, which is equivalent with an atmospheric CO/sub 2/ residence time of 6.8 years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1185657','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1185657"><span>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="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bird, I F; Cornelius, M J; Keys, A J; Whittingham, C P</p> <p>1978-01-01</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>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.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><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('https://www.ncbi.nlm.nih.gov/pubmed/18617793','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18617793"><span>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('http://www.osti.gov/scitech/servlets/purl/835912','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/835912"><span>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://pubs.er.usgs.gov/publication/70024947','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70024947"><span>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/2016EGUGA..1814251Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1814251Y"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/23811127','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23811127"><span>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/2015GeCoA.159..126B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeCoA.159..126B"><span>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.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1198367','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1198367"><span>Metabolism of [1-<span class="hlt">14</span><span class="hlt">C</span>]glyoxylate, [1-<span class="hlt">14</span><span class="hlt">C</span>]-glycollate, [1-<span class="hlt">14</span><span class="hlt">C</span>]glycine and [2-<span class="hlt">14</span><span class="hlt">C</span>]-glycine by homogenates of kidney and liver tissue from hyperoxaluric and control subjects</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Dean, Betty M.; Watts, R. W. E.; Westwick, Wendy J.</p> <p>1967-01-01</p> <p>1. The metabolism of [1-<span class="hlt">14</span><span class="hlt">C</span>]glyoxylate to carbon dioxide, glycine, oxalate, serine, formate and glycollate was investigated in hyperoxaluric and control subjects' kidney and liver tissue in vitro. 2. Only glycine and carbon dioxide became significantly labelled with <span class="hlt">14</span><span class="hlt">C</span>, and this was less in the hyperoxaluric patients' kidney tissue than in the control tissue. 3. Liver did not show this difference. 4. The metabolism of [1-<span class="hlt">14</span><span class="hlt">C</span>]glycollate was also studied in the liver tissue; glyoxylate formation was demonstrated and the formation of 14CO2 from this substrate was likewise unimpaired in the hyperoxaluric patients' liver tissue in these experiments. 5. Glycine was not metabolized by human kidney, liver or blood cells under the conditions used. 6. These observations show that glyoxylate metabolism by the kidney is impaired in primary hyperoxaluria. PMID:5584012</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><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>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('http://adsabs.harvard.edu/abs/2013PhDT.......297L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhDT.......297L"><span>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>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('https://www.osti.gov/scitech/biblio/5163112','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5163112"><span>Transfer of 45Ca and <span class="hlt">36</span><span class="hlt">Cl</span> at the blood-nerve barrier of the sciatic nerve in rats fed low or high calcium diets</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wadhwani, K.C.; Murphy, V.A.; Rapoport, S.I. )</p> <p>1991-04-01</p> <p>Unidirectional fluxes of 45Ca, <span class="hlt">36</span><span class="hlt">Cl</span>, and of (3H)mannitol from blood into the sciatic nerve and cerebral cortex were determined from 5- and 15-min uptakes of these tracers after an intravenous (i.v.) bolus injection in awake rats. Rats were fed diets for 8 wk, that had either a low (0.01% wt/wt), normal (0.67%), or high (3%) Ca content. Plasma (Ca) was 32% less and 11% more in rats fed low (LOCA) and high Ca diets (HICA), respectively, than in rats fed a normal Ca diet (CONT). The mean permeability-surface area product (PA) of 45Ca at the blood-nerve barrier was about eightfold higher than at the blood-brain barrier in the same animals and did not differ significantly between groups (greater than 0.05). Mean PA ratios of 45Ca/<span class="hlt">36</span><span class="hlt">Cl</span> for the blood-nerve and blood-brain barriers in CONT rats, 0.52 {plus minus} 0.04 and 0.40 {plus minus} 0.02, respectively, were not significantly different from corresponding ratios in LOCA and HICA groups, and corresponded to the aqueous limiting diffusion ratio (0.45). The authors results show no evidence for concentration-dependent transport of Ca over a plasma (Ca) range of 0.8-1.4 mmol/liter at the blood-nerve barrier of the rat peripheral nerve, and suggest that Ca and Cl exchange slowly between nerve and blood via paracellular pathways.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017QSRv..162..128J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017QSRv..162..128J"><span>Sub-Antarctic glacier extensions in the Kerguelen region (49°S, Indian Ocean) over the past 24,000 years constrained by <span class="hlt">36</span><span class="hlt">Cl</span> moraine dating</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jomelli, Vincent; Mokadem, Fatima; Schimmelpfennig, Irene; Chapron, Emmanuel; Rinterknecht, Vincent; Favier, Vincent; Verfaillie, Deborah; Brunstein, Daniel; Legentil, Claude; Michel, Elisabeth; Swingedouw, Didier; Jaouen, Alain; Aumaitre, Georges; Bourlès, Didier L.; Keddadouche, Karim</p> <p>2017-04-01</p> <p>Similar to many other regions in the world, glaciers in the southern sub-polar regions are currently retreating. In the Kerguelen Islands (49°S, 69°E), the mass balance of the Cook Ice Cap (CIC), the largest ice cap in this region, experienced dramatic shrinking between 1960 and 2013 with retreat rates among the highest in the world. This observation needs to be evaluated in a long-term context. However, data on the past glacier extents are sparse in the sub-Antarctic regions. To investigate the deglaciation pattern since the Last Glacial Maximum (LGM) period, we present the first 13 cosmogenic <span class="hlt">36</span><span class="hlt">Cl</span> surface exposure ages from four sites in the Kerguelen Islands. The <span class="hlt">36</span><span class="hlt">Cl</span> ages from erratic and moraine boulders span from 24.4 ± 2.7 ka to 0.3 ± 0.1 ka. We combined these ages with existing glacio-marine radiocarbon ages and bathymetric data to document the temporal and spatial changes of the island's glacial history. Ice began to retreat on the main island before 24.4 ± 2.7 ka until around the time of the Antarctic Cold Reversal (ACR) period (∼14.5-12.9 ka), during which the Bontemps moraine was formed by the advance of a CIC outlet glacier. Deglaciation continued during the Holocene probably until 3 ka with evidence of minor advances during the last millennium. This chronology is in pace with major changes in δ18O in a recent West Antarctica ice core record, showing that Kerguelen Islands glaciers are particularly sensitive and relevant to document climate change in the southern polar regions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ApJ...809...31G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ApJ...809...31G"><span>Inferred Initial <span class="hlt">26</span><span class="hlt">Al</span>/27Al Ratios in Presolar Stardust Grains from Supernovae are Higher than Previously Estimated</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Groopman, Evan; Zinner, Ernst; Amari, Sachiko; Gyngard, Frank; Hoppe, Peter; Jadhav, Manavi; Lin, Yangting; Xu, Yuchen; Marhas, Kuljeet; Nittler, Larry R.</p> <p>2015-08-01</p> <p>We performed an in-depth exploration of the Al-Mg system for presolar graphite, SiC, and Si3N4 grains found to contain large excesses of 26Mg, indicative of the initial presence of live <span class="hlt">26</span><span class="hlt">Al</span>. Ninety of the more than 450 presolar grains processed in this study contain well-correlated {δ }26{Mg}{/}24{Mg} and 27Al/24Mg ratios, derived from Nano-scale Secondary Ion Mass Spectrometer depth profiles, whose isochron-like regression lines yield inferred initial {}<span class="hlt">26</span>{<span class="hlt">Al</span>}{/}27{Al} ratios that, on average, are ˜1.5-2 times larger than the ratios previously reported for the grains. The majority of presolar graphite and SiC grains are heavily affected by Al contamination, resulting in large negative {δ }26{Mg}{/}24{Mg} intercepts of the isochron lines. Al contamination is potentially due to etching of the grains’ surfaces and subsequent capture of dissolved Al during the acid dissolution of their meteorite host rocks. From the isochron fits, the magnitude of Al contamination was quantified for each grain. The amount of Al contamination on each grain was found to be random and independent of grain size, following a uniform distribution with an upper bound at 59% contamination. The Al contamination causes conventional whole-grain estimates to underpredict the initial {}<span class="hlt">26</span>{<span class="hlt">Al</span>}{/}27{Al} ratios. The presolar grains with the highest {}<span class="hlt">26</span>{<span class="hlt">Al</span>}{/}27{Al} ratios are from Type II supernovae whose isochron-derived initial {}<span class="hlt">26</span>{<span class="hlt">Al</span>}{/}27{Al} ratios greatly exceed those predicted in the He/C and He/N zones of SN models.</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('https://www.osti.gov/scitech/biblio/21484502','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21484502"><span>COLLATERAL EFFECTS ON SOLAR NEBULA OXYGEN ISOTOPES DUE TO INJECTION OF {sup <span class="hlt">26</span>}<span class="hlt">Al</span> BY A NEARBY SUPERNOVA</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ellinger, Carola I.; Young, Patrick A.; Desch, Steven J.</p> <p>2010-12-20</p> <p>Injection of material from a core-collapse supernova into the solar system's already-formed disk is one proposed mechanism for producing the short-lived radionuclides, such as {sup <span class="hlt">26</span>}<span class="hlt">Al</span> and {sup 41}Ca, inferred from isotopic studies of meteorites to have existed in the solar nebula. This hypothesis has recently been challenged on the basis that the injection of enough supernova material to match the meteoritic abundances of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> and {sup 41}Ca would produce large, measurable, and unobserved collateral effects on oxygen isotopes. Here we calculate again the shifts in oxygen isotopes due to the injection of supernova material in the solar nebula, using a variety of nucleosynthetic conditions of our own progenitor explosions. Unlike previous studies of this type, we also consider the effect of non-homogeneity in abundance distribution of the nucleosynthesis products after the explosion. We calculate the shifts in oxygen isotopes due to the injection of sufficient supernova material to produce the meteoritic abundances of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> and {sup 41}Ca, and analyze the predicted shifts in detail for compatibility with meteoritic data. We find that the range in possible isotopic shifts is considerable and sensitive to parameters such as progenitor mass and anisotropy of the explosion; however, a small number of compatible scenarios do exist. Because of the wide range of outcomes and the sensitivity of isotopic yields to assumed conditions, it is difficult to constrain the supernova that may have led to the injection of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> in the solar nebula. Conversely, we argue that the existence of viable counterexamples demonstrates that it is premature to use oxygen isotopes to rule out the injection of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> and {sup 41}Ca into the solar nebula protoplanetary disk by a nearby supernova.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70185314','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70185314"><span>Estimating <span class="hlt">14</span><span class="hlt">C</span> groundwater ages in a methanogenic aquifer</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Aravena, Ramon; Wassenaar, Leonard I; Plummer, L. Niel</p> <p>1995-01-01</p> <p>This paper addresses the problem of <span class="hlt">14</span><span class="hlt">C</span> age dating of groundwaters in a confined regional aquifer affected by methanogenesis. Increasing CH4 concentrations along the groundwater flow system and 13C and <span class="hlt">14</span><span class="hlt">C</span> isotopic data for dissolved inorganic carbon, dissolved organic carbon, and CH4 clearly show the effect of methanogenesis on groundwater chemistry. Inverse reaction path modeling using NETPATH indicates the predominant geochemical reactions controlling the chemical evolution of groundwater in the aquifer are incongruent dissolution of dolomite, ion exchange, methanogenesis, and oxidation of sedimentary organic matter. Modeling of groundwater <span class="hlt">14</span><span class="hlt">C</span> ages using NETPATH indicates that a significant part of groundwater in the Alliston aquifer is less than 13,000 years old; however, older groundwater in the range of 15,000–23,000 years is also present in the aquifer. This paper demonstrates that <span class="hlt">14</span><span class="hlt">C</span> ages calculated using NETPATH, incorporating the effects of methanogenesis on the carbon pools, provide reasonable groundwater ages that were not possible by other isotopic methods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21036066','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21036066"><span>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('https://www.osti.gov/scitech/biblio/5818632','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5818632"><span>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('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>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>... director or officer of the registrant or any of its parents or subsidiaries. (b) Employee benefit plan. For purposes of § 240.<span class="hlt">14</span><span class="hlt">c</span>-7, the term “employee benefit plan” means any purchase, savings, option, bonus..., trustees or officers. (c) Entity that exercises fiduciary powers. The term “entity that exercises...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5159662','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5159662"><span>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://pubs.er.usgs.gov/publication/70037122','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70037122"><span>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>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('https://www.osti.gov/scitech/biblio/6967766','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6967766"><span>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('https://www.osti.gov/scitech/biblio/21305099','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21305099"><span>EARLY SOLAR NEBULA CONDENSATES WITH CANONICAL, NOT SUPRACANONICAL, INITIAL {sup <span class="hlt">26</span>}<span class="hlt">Al</span>/{sup 27}Al RATIOS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>MacPherson, G. J.; Bullock, E. S.; Janney, P. E.; Wadhwa, M.; Kita, N. T.; Ushikubo, T.; Davis, A. M.; Krot, A. N.</p> <p>2010-03-10</p> <p>The short-lived radionuclide {sup <span class="hlt">26</span>}<span class="hlt">Al</span> existed throughout the solar nebula 4.57 Ga ago, and the initial abundance ratio ({sup <span class="hlt">26</span>}<span class="hlt">Al</span>/{sup 27}Al){sub 0}, as inferred from magnesium isotopic compositions of calcium-aluminum-rich inclusions (CAIs) in chondritic meteorites, has become a benchmark for understanding early solar system chronology. Internal mineral isochrons in most CAIs measured by secondary ion mass spectrometry (SIMS) give ({sup <span class="hlt">26</span>}<span class="hlt">Al</span>/{sup 27}Al){sub 0} {approx} (4-5) x 10{sup -5}, called 'canonical'. Some recent high-precision analyses of (1) bulk CAIs measured by multicollector inductively coupled plasma mass spectrometry (MC-ICPMS), (2) individual CAI minerals and their mixtures measured by laser-ablation MC-ICPMS, and (3) internal isochrons measured by multicollector (MC)-SIMS indicated a somewhat higher 'supracanonical' ({sup <span class="hlt">26</span>}<span class="hlt">Al</span>/{sup 27}Al){sub 0} ranging from (5.85 {+-} 0.05) x 10{sup -5} to >7 x 10{sup -5}. These measurements were done on coarse-grained Type B and Type A CAIs that probably formed by recrystallization and/or melting of fine-grained condensate precursors. Thus the supracanonical ratios might record an earlier event, the actual nebular condensation of the CAI precursors. We tested this idea by performing in situ high-precision magnesium isotope measurements of individual minerals in a fine-grained CAI whose structures and volatility-fractionated trace element abundances mark it as a primary solar nebula condensate. Such CAIs are ideal candidates for the fine-grained precursors to the coarse-grained CAIs, and thus should best preserve a supracanonical ratio. Yet, our measured internal isochron yields ({sup <span class="hlt">26</span>}<span class="hlt">Al</span>/{sup 27}Al){sub 0} = (5.27 {+-} 0.17) x 10{sup -5}. Thus our data do not support the existence of supracanonical ({sup <span class="hlt">26</span>}<span class="hlt">Al</span>/{sup 27}Al){sub 0} = (5.85-7) x 10{sup -5}. There may not have been a significant time interval between condensation of the CAI precursors and their subsequent melting into coarse-grained CAIs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6551412','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6551412"><span>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/2003GeCoA..67.4529S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003GeCoA..67.4529S"><span>Origin and history of waters associated with coalbed methane: 129I, <span class="hlt">36</span><span class="hlt">Cl</span>, and stable isotope results from the Fruitland Formation, CO and NM</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Snyder, Glen T.; Riese, Walter C."Rusty"; Franks, Stephen; Fehn, Udo; Pelzmann, William L.; Gorody, Anthony W.; Moran, Jean E.</p> <p>2003-12-01</p> <p>The Fruitland Formation of the San Juan Basin was deposited during the late Cretaceous and is associated with significant reservoirs of coalbed methane (CBM). The purpose of this study is to determine the origin and history of waters associated with the formation, using long-lived cosmogenic and stable isotope systems. Ratios of 129I/I and stable isotope values (δD and δ 18O) were determined in waters from close to 100 wells, <span class="hlt">36</span><span class="hlt">Cl</span>/Cl ratios for a subset of these samples. A significant group of samples has 129I/I ratios between 100 × 10 -15 and 200 × 10 -15, indicating minimum iodine ages close to 60 Ma. If these ages are corrected for the addition of fissiogenic 129I, they are compatible with the depositional age of the Fruitland Formation (Late Cretaceous). Several sets of waters are clearly present within the data. A group dominated by infiltration of recent surface waters is restricted to the uplifted basin margins, with a lateral extent of less than 5 km from outcrop, and is characterized by 129I/I ratios in excess of 1500 × 10 -15 and meteoric δD, δ 18O, and <span class="hlt">36</span><span class="hlt">Cl</span>/Cl signatures. The rest of the basin is characterized by several subsets of formation waters which have undergone variable degrees of iodine enrichment through diagenesis as well as variable degrees of dilution. The first subgroup is found in coals of relatively low vitrinite reflectance and moderate enrichment of iodine. This subgroup predominantly consists of entrapped pore fluids, although it may also contain waters which infiltrated the coals at the time of the Laramide uplift, between 25 and 30 Ma. A second subgroup consists of formation waters associated with coals of high vitrinite reflectance. Despite subsequent uplift, the high iodine concentrations and low 129I/I ratios of this subgroup, as well as a moderate depletion of deuterium relative to 18O, suggest that these waters were not significantly altered since the time when diagenetic reactions occurred in the deepest portion of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DNP.FE006C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DNP.FE006C"><span>Cluster Structure and 3-body decay in <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>Carpenter, Lisa; Bazin, D.; Mittig, W.; Ayyad, Y.; Beceiro Novo, S.; Bradt, J.; Ahn, T.; Kolata, J. J.; Becchetti, F. D.; Fritsch, A.</p> <p>2016-09-01</p> <p>Recent model calculations with most advanced methods for cluster states have shown the need of experimental data to probe the structure of light exotic nuclei, including those with α-clustering, such as <span class="hlt">14</span><span class="hlt">C</span>. The Prototype Active Target Time Projection Chamber (PAT-TPC) allows us to investigate these types of structures, giving access to the full excitation function with a single beam energy. This type of experiment measures resonances in <span class="hlt">14</span><span class="hlt">C</span> that can be compared to the models. With an improved Micromegas pad plane with a circular backgammon design we are able to investigate 3-body decays in addition to 2-body scattering. The measurements were carried out by resonant alpha-scattering on 10Be beam delivered by the TwinSol facility at the University of Notre Dame. This work is supported by the National Science Foundation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24493347','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24493347"><span>The behaviour of (<span class="hlt">14</span>)<span class="hlt">C</span> profiles in Helianthus seedlings.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Whittle, C M</p> <p>1971-06-01</p> <p>The log. (<span class="hlt">14</span>)<span class="hlt">C</span> activity/distance profile in the stems of Helianthus seedlings consists of two main parts: region 1, the linear advancing front and region 2, which is also linear but with a less steep slope. As the front passes down the stem, the slope of region 1 remains constant but the amplitude of the front becomes attenuated. The attenuation increases with temperature. The apparent velocity of the profile, which can be derived from the position of the front, is also temperature dependent. Small amounts of (<span class="hlt">14</span>)<span class="hlt">C</span> occur in the stem ahead of the profile; these amounts increase with a rise of temperature. Region 2 behaves differently: its slope decreases steadily with time but it is insensitive to temperature. The behaviour of this region is dependent on the movement of tracer into an immobile fraction as well as on the longitudinal movement of tracer in the translocation stream.</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>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/2007AGUFM.S43A1060S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.S43A1060S"><span>Large Earthquake Repeat on Normal Faults: Insights from dense in-situ <span class="hlt">36</span><span class="hlt">Cl</span> Exposure Dating of Limestone Fault Scarps, Central Apennines, 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.; Benedetti, L.; Manighetti, I.</p> <p>2007-12-01</p> <p>The only chance to learn how major earthquakes have repeated in the past on major active faults is to analyze their surface geological record, if any. We analyze such a record on 11 active normal faults to seek identifying, dating and measuring the large earthquake ruptures that have broken these faults in the last 10-20 kyrs, and determine how these major ruptures have followed in space and time on each fault and from one fault to another. As large earthquakes repeat on a normal fault, the fault plane is progressively exhumed and exposed at the free air, forming an escarpment at the surface. Provided that this escarpment is preserved from erosion, its surface holds the complete record of the successive ruptures (and possible aseismic slip) as they have broken the ground surface. We have started to analyze such a record on 11 neighboring, likely interacting active faults in the Fucino area, Central Italy, where seismic activity can be devastating (1915, M7 Avezzano earthquake, 30 000 casualties). Faults offset limestone rocks and form several hundred meters high cumulative escarpments, whose youngest parts (10-20 kyrs) are well preserved in the form of 10-20 m high, steep scarps running along the fault lengths (10-20 km). The Holocene seismic slip history of the faults can be recovered from base-to-top continuous in-situ <span class="hlt">36</span><span class="hlt">Cl</span> exposure dating of the limestone scarps (Benedetti et al. 2002, 2003; Palumbo et al. 2004). To reach that objective, we have sampled the faults in two different ways: two faults (Magnola and Roccapreturo) were sampled at several, regularly spaced sites along their length, so that to recover the earthquake slip variability in both space and time. Nine other faults (Fiamigniano, Campo-Felice, Velino, Tre- Monti, Trasacco, Parasano, San Sebastiano, Castel di Ieri, Roccacasale) were sampled at one single spot along their length, so that to examine the possible earthquake interactions within the entire fault system. Doing so, we have collected one</p> </li> <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>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://pubs.er.usgs.gov/publication/70030141','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70030141"><span>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> <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><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://adsabs.harvard.edu/abs/2015PhRvC..92b4624O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhRvC..92b4624O"><span>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> </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('https://www.osti.gov/scitech/biblio/5491023','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5491023"><span>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('https://www.osti.gov/scitech/biblio/21199603','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21199603"><span>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('https://www.osti.gov/scitech/biblio/21448880','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21448880"><span>{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('https://www.osti.gov/scitech/biblio/6082669','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6082669"><span>Amount and identity of (/sup <span class="hlt">14</span>/<span class="hlt">C</span>) residues in bluegills (Lepomis macrochirus) exposed to (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)triclopyr</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lickly, T.D.; Murphy, P.G.</p> <p>1987-01-01</p> <p>The level and identity of (/sup <span class="hlt">14</span>/<span class="hlt">C</span>) residues in bluegills (Lepomis macrochirus) exposed to 2.5 mg/L (/sup <span class="hlt">14</span>/<span class="hlt">C</span>) triclopyr (3,5,6-trichloro-2-pyridinyloxyacetic acid) have been determined. The highest level of radioactivity observed in the flesh of a fish at any time point (0.13 mg/kg, calculated as equivalent mg triclopyr/kg fish) was less than 5% of the fish exposure level of 2.5 mg/L, while the maximum level in the remainder (head, skin, and viscera) was about 95% (2.33 mg/kg) of the fish exposure level, indicating no concentrating effect. The principal components observed in the fish tissues were triclopyr, 3,5,6-trichloro-2-pyridinol, 2-methoxy-3,5,6-trichloropyridine and a conjugate. These components accounted for greater than 75% of all the residues observed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/452098','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/452098"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/6154443','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/6154443"><span>Influence of selected pesticides on the microbial degradation of <span class="hlt">14</span><span class="hlt">C</span>-triallate and <span class="hlt">14</span><span class="hlt">C</span>-diallate 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>Anderson, J P; Domsch, K H</p> <p>1980-01-01</p> <p>Degradation in soil of [allyl-2-<span class="hlt">14</span><span class="hlt">C</span>]triallate and [carbonyl-<span class="hlt">14</span><span class="hlt">C</span>]diallate herbicides, as affected by other selected pesticides, was studied in an incubation system that allowed recovery of 95 to 100% of added <span class="hlt">14</span><span class="hlt">C</span>. The amount and sequence of pesticide additions simulated field use in the protection of wheat (triallate) and sugar beets (diallate). Neither the rate nor the pattern of triallate degradation in soil was influenced by the following sequence of formulated pesticides: dinoseb acetate, (bentazon + dichlorprop + 2,4,5-T), 2,4-D, (chlorcholinchloride + cholinchloride), tridemorph, and thiophanate. Similarly, diallate degradation was unaffected by pyrazon, dimethoate, and thiophanate. The effect of azinphosmethyl was unclear. In contrast, chlorpyrifos reduced diallate degradation by approximately 14% relative to the occurring in the insecticide's absence. This effect was caused by chlorpyrifos and not its formulation components. Chlorpyrifos was also found to partially inhibit degradation of triallate in soil. Inhibition of neither herbicide was considered to be of ecological significance. Triallate, diallate, and thiophanate were applied at 1 microgram/g; all others were at 2 microgram/g.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5077992','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5077992"><span>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('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>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-2012-title17-vol3/pdf/CFR-2012-title17-vol3-sec240-14c-3.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title17-vol3/pdf/CFR-2012-title17-vol3-sec240-14c-3.pdf"><span>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=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-04-01</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-2014-title17-vol4/pdf/CFR-2014-title17-vol4-sec240-14c-3.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title17-vol4/pdf/CFR-2014-title17-vol4-sec240-14c-3.pdf"><span>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=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-04-01</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-2013-title17-vol3/pdf/CFR-2013-title17-vol3-sec240-14c-3.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title17-vol3/pdf/CFR-2013-title17-vol3-sec240-14c-3.pdf"><span>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=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-04-01</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.osti.gov/scitech/servlets/purl/7980','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/7980"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/23671077','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23671077"><span>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://adsabs.harvard.edu/abs/2015NIMPB.361..659D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NIMPB.361..659D"><span>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/2003EAEJA....11550N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA....11550N"><span><span class="hlt">14</span><span class="hlt">C</span> Concentrations in the Northern Atlantic and Nordic Seas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nadeau, M.-J.; Grootes, P. M.; Erlenkeuser, H.</p> <p>2003-04-01</p> <p>We report here more than 450 new Δ<span class="hlt">14</span><span class="hlt">C</span> results from water samples from the North Atlantic and the Nordic Seas measured at the Leibniz-Labor, Christian-Albrechts Universität, Kiel, using accelerator mass spectrometry. The water samples were collected during three cruises of the RV Meteor: M36 in 1996 (65 measurements, 6 stations), M39 in 1997 (217 measurements, 11 stations) and M50 in 2001 (189 measurements, 10 stations). These results are compared to those of previous sampling campaigns: GEOSECS (1972) and TTO (1981) and of samples obtained from previous cruises of the RV Meteor (M18 in 1991 and M30 in 1994) measured by decay counting at the Institut für Umweltphysik in Heidelberg. Several stations from the cruise M50 are located along the WOCE A02 line from the western entrance of the English Channel to the tip of Newfoundland/Grand Banks. This transect also analysed during the M30 (1994) campaign provides the evolution of the penetration of atmospheric bomb <span class="hlt">14</span><span class="hlt">C</span> into these waters over a seven year period. Other samples were taken in the Labrador Sea, and North and South of Iceland. Comparison with CFC measurements, for some of the stations, also provides an insight in the penetration of both tracers into the ocean.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.T13C4671J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.T13C4671J"><span>Seismic slip history of the Aterno-Sulmona fault system in central Apennines (Italy) using in situ produced <span class="hlt">36</span><span class="hlt">Cl</span> cosmic ray 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>Jim, T.; Benedetti, L. C.; Bruno, P.; Visini, F.; Aumaitre, G.; Bourles, D. L.</p> <p>2014-12-01</p> <p>Acquiring long records of past earthquakes on a large population of faults is a key step to understand how strain release along those fault systems varies spatially and temporally.In central Italy, NE-SW extension (~4 mm/yr) is accommodated on a wide normal fault system (50 x 100km). Benedetti et al. (2013) found that 7 of these faults, belonging to the Fucino fault system, have their seismic activity synchronized during short (less than 1 ka) paroxysmal phases of activity. <span class="hlt">36</span><span class="hlt">Cl</span> measurements and rare earth elements (REE) concentrations were used to reconstruct the seismic slip history of four major faults belonging to an adjacent 30-km-long fault system, the Aterno-Sulmona fault system, at the southeastward tip of the Paganica fault that ruptured during the 2009 L'Aquila earthquake.The preliminary results suggest that 3-7 seismic events have occurred on each fault over the last 11 ka (from NE to SW the Roccapreturo, the Castel di Ieri, the Roccacasale and the Pizzalto faults), with 50 cm to 2 m of associated slip per event. These events appear clustered within intense period of seismic activity lasting less than 1ka (2 to 4 seismic events) separated by 2 to 3 ka periods with no seismic events. The most recent recorded paroxysmal activity occurred about 2.5 ka ago with all four studied faults rupturing in more than 15 earthquakes over a period lasting less than 1ka. These results thus suggest that, as already observed on the Fucino fault system, the seismic activity of the Aterno-Sulmona fault system is also synchronized during short periods of paroxysmal seismic activity.When clustering periods are compared, the seismic activity of the Fucino and the Aterno-Sulmona fault system, are, however, apparently unsynchronized since the most recent clustering period for the Aterno-Sulmona system corresponds to a quiescent period for the Fucino fault system.</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>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/1996LPI....27..549H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996LPI....27..549H"><span>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('http://adsabs.harvard.edu/abs/2015GeCoA.158..245D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeCoA.158..245D"><span>Isotopic mass fractionation laws for magnesium and their effects on <span class="hlt">26</span><span class="hlt">Al</span>-26Mg systematics in solar system materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Davis, Andrew M.; Richter, Frank M.; Mendybaev, Ruslan A.; Janney, Philip E.; Wadhwa, Meenakshi; McKeegan, Kevin D.</p> <p>2015-06-01</p> <p>Magnesium isotope ratios are known to vary in solar system objects due to the effects of <span class="hlt">26</span><span class="hlt">Al</span> decay to 26Mg and mass-dependent fractionation, but anomalies of nucleosynthetic origin must also be considered. In order to infer the amount of enhancement of 26Mg/24Mg due to <span class="hlt">26</span><span class="hlt">Al</span> decay or to resolve small nucleogenetic anomalies, the exact relationship between 26Mg/24Mg and 25Mg/24Mg ratios due to mass-dependent fractionation, the mass-fractionation "law", must be accurately known so that the 25Mg/24Mg ratio can be used to correct the 26Mg/24Mg ratio for mass fractionation. Mass-dependent fractionation in mass spectrometers is reasonably well characterized, but not necessarily fully understood. It follows a simple power fractionation law, sometimes referred to as the "exponential law". In contrast, mass fractionation in nature, in particular that due to high temperature evaporation that likely caused the relatively large effects observed in calcium-, aluminum-rich inclusions (CAIs), is reasonably well understood, but mass-fractionation laws for magnesium have not been explored in detail. The magnesium isotopic compositions of CAI-like evaporation residues produced in a vacuum furnace indicate that the slope on a log 25Mg/24Mg vs. log 26Mg/24Mg plot is ∼0.5128, and different from those predicted by any of the commonly used mass-fractionation laws. Evaporation experiments on forsterite-rich bulk compositions give exactly the same slope, indicating that the measured mass-fractionation law for evaporation of magnesium is applicable to a wide range of bulk compositions. We discuss mass-fractionation laws and the implications of the measured fractionation behavior of magnesium isotopes for <span class="hlt">26</span><span class="hlt">Al</span>-26Mg chronology.</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>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> </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('http://adsabs.harvard.edu/abs/2015NIMPB.361..559T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NIMPB.361..559T"><span>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.ncbi.nlm.nih.gov/pubmed/26665189','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26665189"><span>[Measuring <span class="hlt">14</span><span class="hlt">C</span>-glucose and <span class="hlt">14</span><span class="hlt">C</span>-acetate oxidation in tumour cells and tumorous host organism].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hujber, Zoltán; Jeney, András; Oláh, Júlia; Szoboszlai, Norbert; Baranyai, Lajos; Környei, József; Petõvári, Gábor; Sebestyén, Anna</p> <p>2015-12-01</p> <p>Tumour cell metabolism can be influenced by alterations of the extracellular microenvironment and the tumour-promoting genetically changed mechanisms. There is increasing interest to introduce appropriate bioenergetic assays to describe the therapeutic effect and metabolic subtypes of tumours in clinical oncology. The analysis of <span class="hlt">14</span><span class="hlt">C</span>-glucose and <span class="hlt">14</span><span class="hlt">C</span>-acetate oxidation could be a suitable method to examine the metabolic/bioenergetic profiles of tumour cells and tumorous host organisms. The metabolic activity of tumour cells (in vitro cell lines, primary human lymphocytes and leukaemia cells) and the tumourous host organism were examined in vitro and in vivo by detecting the released CO2 levels derived from the radioactive carbon atom labelled energy substrates. We have found that the most cancer cells of solid tumours oxidised glucose more intensively than acetate. It was interesting that AML, CML and CLL cells isolated from blood preferred acetate as an energy substrate in vitro. Furthermore, based on our observations, tumours affected the glucose or acetate oxidation of the organism when applying bioenergetic substrates per os or iv. We provided the first data about the alterations in metabolic profiles of the tumour bearing organism in xenograft models. In summary, according to our results, comparison of the energy substrate oxidation can be an indicative method related to the metabolic profile analysis of tumour cells in vitro and tumorous host organism in vivo.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhRvC..94f5804A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvC..94f5804A"><span>Experimental study of the astrophysically important 23Na(α ,p )26Mg and 23Na(α ,n )<span class="hlt">26</span><span class="hlt">Al</span> reactions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Avila, M. L.; Rehm, K. E.; Almaraz-Calderon, S.; Ayangeakaa, A. D.; Dickerson, C.; Hoffman, C. R.; Jiang, C. L.; Kay, B. P.; Lai, J.; Nusair, O.; Pardo, R. C.; Santiago-Gonzalez, D.; Talwar, R.; Ugalde, C.</p> <p>2016-12-01</p> <p>The 23Na(α ,p )26Mg and 23Na(α ,n )<span class="hlt">26</span><span class="hlt">Al</span> reactions are important for our understanding of the <span class="hlt">26</span><span class="hlt">Al</span> abundance in massive stars. The aim of this work is to report on a direct and simultaneous measurement of these astrophysically important reactions using an active target system. The reactions were investigated in inverse kinematics using 4He as the active target gas in the detector. We measured the excitation functions in the energy range of about 2 to 6 MeV in the center of mass. We have found that the cross sections of the 23Na(α ,p )26Mg and the 23Na(α ,n )<span class="hlt">26</span><span class="hlt">Al</span> reactions are in good agreement with previous experiments and with statistical-model calculations. The astrophysical reaction rate of the 23Na(α ,n )<span class="hlt">26</span><span class="hlt">Al</span> reaction has been reevaluated and it was found to be larger than the recommended rate.</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>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('https://www.ncbi.nlm.nih.gov/pubmed/6628439','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/6628439"><span>A new metabolically trapped agent by brain monoamine oxidase: N-methyl labeled (<span class="hlt">14</span><span class="hlt">C</span>) N-methylphenylethylamine (<span class="hlt">14</span><span class="hlt">C</span>-MPEA).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Osamu, I</p> <p>1983-01-01</p> <p>A new type of metabolically trapped agent for measuring regional brain function was designed and evaluated. N-methylphenylethylamine (<span class="hlt">14</span><span class="hlt">C</span>-MPEA) was synthesized with trifluoroacetylphenylethylamine and <span class="hlt">14</span><span class="hlt">C</span>-methyl iodide. A high concentration of <span class="hlt">14</span><span class="hlt">C</span>-MPEA accumulated in mouse brain 1 min after injection, and radioactivities in the brain remained for a long period. By radiochemical analysis, it was found <span class="hlt">14</span><span class="hlt">C</span>-MPEA was metabolized in the brain to <span class="hlt">14</span><span class="hlt">C</span>-methylamine. <span class="hlt">14</span><span class="hlt">C</span>-methylamine was trapped by the blood-brain barrier because of its cationic charge at physiological pH. When the mouse was pretreated with a MAO inhibitor (pargyline hydrochloride 100 mg/kg IP) the radioactivity was rapidly excreted from the brain with a half-life of about 45 min. These results indicate that 11C-MPEA has potential for the measurement of brain MAO activity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6524602','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6524602"><span>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('https://www.osti.gov/scitech/biblio/6142673','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6142673"><span>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('https://www.osti.gov/scitech/biblio/5777403','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5777403"><span>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://adsabs.harvard.edu/abs/2015NIMPB.361..431M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NIMPB.361..431M"><span>Carbonates in leaching reactions in context of <span class="hlt">14</span><span class="hlt">C</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>Michalska, Danuta; Czernik, Justyna</p> <p>2015-10-01</p> <p>Lime mortars as a mixture of binder and aggregate may contain carbon of various origins. If the mortars are made of totally burnt lime, radiocarbon dating of binder yields the real age of building construction. The presence of carbonaceous aggregate has a significant influence on the <span class="hlt">14</span><span class="hlt">C</span> measurements results and depending on the type of aggregate and fraction they may cause overaging. Another problem, especially in case of hydraulic mortars that continue to be chemically active for a very long time, is the recrystallization usually connected with rejuvenation of the results but also, depending on local geological structures, with so called reservoir effect yielding apparent ages. An attempt in separating the binder from other carbonaceous components successfully was made for samples from Israel by Nawrocka-Michalska et al. (2007). The same preparation procedure, after taking into account the petrographic composition, was used for samples coming from Poland, Nawrocka et al. (2009). To verify the procedure used previously for non-hydraulic samples determination an experimental tests on carbonaceous mortars with crushed bricks from Novae in Bulgaria were made. Additionally, to identify different carbonaceous structures and their morphology, a cathodoluminescence and scanning electron microscope with electron dispersive spectrometer were applied. The crushed bricks and brick dust used in mortars production process have been interpreted as an alternative use to other pozzolanic materials. The reaction between lime and pozzolanic additives take place easily and affects the rate and course of carbonates decomposition in orthophosphric acid, during the samples pretreatment for dating. The composition of the Bulgarian samples together with influence of climate conditions on mortar carbonates do not allow for making straightforward conclusions in chronology context, but gives some new guidelines in terms of hydraulic mortars application for dating. This work has mainly</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9725486','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9725486"><span><span class="hlt">14</span><span class="hlt">C</span>-NaVP and <span class="hlt">14</span><span class="hlt">C</span>-PEV repeated dose study in rat. Pharmacokinetic study in rats after repeated oral administrations of <span class="hlt">14</span><span class="hlt">C</span>-valproic acid sodium salt and <span class="hlt">14</span><span class="hlt">C</span>-valproic acid pivaloyl oxymethyl ester.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bertolino, M; Acerbi, D; Canali, S; Giachetti, C; Poli, G; Ventura, P; Zanolo, G</p> <p>1998-01-01</p> <p>The absorption, excretion and tissue distribution of radioactivity after repeated oral equimolar doses of <span class="hlt">14</span><span class="hlt">C</span>-valproic acid sodium salt (NaVP) or <span class="hlt">14</span><span class="hlt">C</span>-valproic acid pivaloyl oxymethyl ester (PEV) was investigated in male rats treated once a day for 14 consecutive days. The 14th day plasma time-course of radioactivity after PEV administrations was characterised by a slow absorption rate with a delayed peak (tmax 2 h, Cmax 7.52 +/- 1.35 microg eq./ml), followed by a plateau lasting up to 8 h. After NaVP treatment, the main peak of radioactivity was observed 0.5 h after administration (Cmax 8.30 +/- 1.26 microg eq./ml) followed by a secondary peak due to biliary enterohepatic recycling. Starting from 4 h onwards, radioactivity levels after PEV treatment were higher than those after NaVP (AUCtau = 113.3 h.microg eq./ml after PEV vs 71.9 h.microg eq./ml after NaVP), but concentrations declined with similar terminal half-lives (52.8 h for PEV and 49.7 h for NaVP). Radioactivity recovered (0-432 h interval) in urine accounted for 79.3% (PEV) and 56.1% (NaVP) while, in faeces accounted for 9.1% (PEV) and 26.1% (NaVP) of total administered dose (14 days). The difference is attributable to a higher excretion of radioactivity in the bile for NaVP. The missing fraction in the total radioactivity balance is probably excreted in expired air, as observed in single dose studies. Radioactivity excreted in bile (0-8 h interval of the last 14th day) accounted for 5.1% (NaVP) and 0.23% (PEV) of the total administered dose (14 days). A possible explanation of this difference may be a different metabolism pattern for the two compounds. The negligible biliary excretion observed after PEV administration is probably due to an inhibition of the glucuronation of valproic acid (or other metabolites) caused by the pivalic acid. Due to the presence of the enterohepatic recycle, the radioactivity levels in intestine, 0.5 and 2 h after administration, were higher after NaVP administration</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=151303&keyword=nurse&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=78690222&CFTOKEN=56075857','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=151303&keyword=nurse&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=78690222&CFTOKEN=56075857"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/10552735','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10552735"><span>Metabolism of [(1)(4)C]prometryn 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>Maynard, M S; Brumback, D; Itterly, W; Capps, T; Rose, R</p> <p>1999-09-01</p> <p>[(1)(4)C]Prometryn, 2, 4-bis(isopropylamino)-6-(methylthio)-s-triazine, was orally administered to male and female rats at approximately 0.5 and 500 mg/kg; daily urine and feces were collected. After 3 or 7 days rats were sacrificed, and blood and selected tissues were isolated. The urine and feces extracts were characterized for metabolite similarity as well as for metabolite identification. Over 30 metabolites were observed, and of these, 28 were identified mostly by mass spectrometry and/or cochromatography with available reference standards. The metabolism of prometryn was shown to occur by N-demethylation, S-oxidation, S-S dimerization, OH substitution for NH(2) and SCH(3), and conjugation with glutathione or glucuronic acid. Rat liver microsomal incubations of prometryn were conducted and compared to the in vivo metabolism. Both in vivo and in vitro phase I metabolisms of prometryn were similar, with S-oxidation and N-dealkylation predominating. The involvement of cytochrome P-450 and flavin-containing monooxidase in the in vitro metabolism of prometryn was investigated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013NIMPB.294..328L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013NIMPB.294..328L"><span>Carbonate as sputter target material for rapid <span class="hlt">14</span><span class="hlt">C</span> AMS</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Longworth, Brett E.; Robinson, Laura F.; Roberts, Mark L.; Beaupre, Steven R.; Burke, Andrea; Jenkins, William J.</p> <p>2013-01-01</p> <p>This paper describes a technique for measuring the <span class="hlt">14</span><span class="hlt">C</span> content of carbonate samples by producing C- ions directly in the negative ion sputter source of an accelerator mass spectrometer (AMS) system. This direct analysis of carbonate material eliminates the time and expense of graphite preparation. Powdered carbonate is mixed with titanium powder, loaded into a target cartridge, and compressed. Beam currents for optimally-sized carbonate targets (0.09-0.15 mg C) are typically 10-20% of those produced by optimally-sized graphite targets (0.5-1 mg C). Modern (>0.8 Fm) samples run by this method have standard deviations of 0.009 Fm or less, and near-modern samples run as unknowns agree with values from traditional hydrolysis/graphite to better than 2%. Targets with as little as 0.06 mg carbonate produce useable ion currents and results, albeit with increased error and larger blank. In its current state, direct sputtering is best applied to problems where a large number of analyses with lower precision are required. These applications could include age surveys of deep-sea corals for determination of historic population dynamics, to identify samples that would benefit from high precision analysis, and for growth rate studies of organisms forming carbonate skeletons.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1161970','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1161970"><span>Quantitative measurement of the L-type pentose phosphate cycle with [2-<span class="hlt">14</span><span class="hlt">C</span>]glucose and [5-<span class="hlt">14</span><span class="hlt">C</span>]glucose in isolated hepatocytes.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Longenecker, J P; Williams, J F</p> <p>1980-01-01</p> <p>1. Investigations of the mechanism of the non-oxidative segment of the pentose phosphate cycle in isolatd hepatocytes by prediction-labelling studies following the metabolism of [2-<span class="hlt">14</span><span class="hlt">C</span>]-, [5-<span class="hlt">14</span><span class="hlt">C</span>]- and [4,5,6-<span class="hlt">14</span><span class="hlt">C</span>]glucose are reported. The <span class="hlt">14</span><span class="hlt">C</span> distribution patterns in glucose 6-phosphate show that the reactions of the L-type pentose pathway in hepatocytes. 2. Estimates of the quantitative contribution of the L-type pentose cycle are the exclusive form of the pentose cycle to glucose metabolism have been made. The contribution of the L-type pentose cycle to the metabolism of glucose lies between 22 and 30% in isolated hepatocytes. 3. The distribution of <span class="hlt">14</span><span class="hlt">C</span> in the carbon atoms of glucose 6-phosphate following the metabolism of [4,5,6-<span class="hlt">14</span><span class="hlt">C</span>]- and [2-<span class="hlt">14</span><span class="hlt">C</span>]glucose indicate that gluconeogenesis from triose phosphate and non-oxidative formation of pentose 5-phosphate do not contribute significantly to randomization of <span class="hlt">14</span><span class="hlt">C</span> in isolated hepatocytes. The transaldolase exchange reaction between fructose 6-phosphate and glyceraldehyde 3-phosphate is very active in these cells. PMID:7470039</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5965636','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5965636"><span>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/2007NIMPB.259..600F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007NIMPB.259..600F"><span>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.osti.gov/scitech/biblio/22167129','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22167129"><span>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('https://www.osti.gov/scitech/biblio/5508610','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5508610"><span>(<span class="hlt">14</span><span class="hlt">C</span>)deoxyglucose uptake and imaging in malignant melanoma</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kern, K.A. )</p> <p>1991-06-01</p> <p>Since malignant tumors utilize more glucose than normal tissues, tumor uptake and autoradiographic imaging studies using the <span class="hlt">14</span><span class="hlt">C</span>-labeled glucose analog 2-deoxyglucose (DG) provide a useful preclinical system to determine if similar human tumors will image in vivo with positron emission tomography (PET) using 18F-labeled DG (FDG-PET). We studied B16 murine melanomas of increasing metastatic potential (F1, low; BL-6, intermediate; F10, high) as a feasibility study to determine the potential for human melanoma imaging using FDG-PET. Male C57BL-6 mice (50 g) were implanted sc with 1-mm3 fragments of B16 melanomas. Fourteen days later mice were injected ip with 1.25 muCi of {sup 14}CDG. Sixty minutes later tumor (T) and gastrocnemius muscle (M) were harvested, solubilized, and counted for {sup 14}CDG dpm/mg to estimate glucose utilization. Autoradiographic imaging was carried out similarly, using 2.0 muCi or {sup 14}CDG with 30-day exposure of T and M tissue sections (20 microns thick) to x-ray film. The uptake of {sup 14}CDG (expressed as dpm/mg; % injected dose/g; and tumor-to-muscle uptake ratios) was 6 to 10 times higher in tumors than in muscle tissue (P less than 0.001). All three melanoma cell lines imaged successfully with {sup 14}CDG autoradiography. Tumor uptake of {sup 14}CDG did not correlate with increasing metastatic potential. The experimental B16 murine melanomas F1, BL-6, and F10 extract glucose at higher rates than muscle tissue, a property necessary for successful PET imaging of cutaneous melanoma. The lack of correlation between glucose extraction and metastatic potential suggests that the demands for glucose during tumor growth and metastasis are not related. This is the first laboratory study to predict that human malignant melanoma will image with FDG-PET.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1086732','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1086732"><span>Translocation of Indole-3-acetic Acid-1′-<span class="hlt">14</span><span class="hlt">C</span> and Tryptophan-1-<span class="hlt">14</span><span class="hlt">C</span> in Seedlings of Phaseolus coccineus L. and Zea mays 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>Whitehouse, R. L.; Zalik, Saul</p> <p>1967-01-01</p> <p>Indole-3-acetic acid-1′-<span class="hlt">14</span><span class="hlt">C</span> (IAA-<span class="hlt">14</span><span class="hlt">C</span>) and tryptophan-1-<span class="hlt">14</span><span class="hlt">C</span> injected in small amounts into cotyledons of Phaseolus coccineus L. seedlings were found to be translocated acropetally into the epicotyls and young shoots. Similarly IAA-<span class="hlt">14</span><span class="hlt">C</span> was translocated acropetally into coleoptiles of Zea mays following injection into the endosperms. Labeled metabolites of the injected compounds were also extractable from shoot tissue. However, evidence that IAA-<span class="hlt">14</span><span class="hlt">C</span> itself was translocated acropetally was obtained by collection in agar blocks applied to cut surfaces of coleoptiles of injected seedlings. The acropetal translocation in Phaseolus was shown not to occur in the transpiration stream but in living tissue. Cotyledons of Phaseolus coccineus and Phaseolus vulgaris contain extensive vascular tissue. Tryptophan-<span class="hlt">14</span><span class="hlt">C</span> was not actively translocated through excised segments of Phaseolus coccineus epicotyl and Zea mays coleoptile when supplied from donor agar blocks in concentrations as high as 100 μm. The small amount of tryptophan-<span class="hlt">14</span><span class="hlt">C</span> which did reach receiver blocks when high concentrations were used may be accounted for by passive diffusion through the fluid-filled xylem vessels. Translocation of a non-toxic dye, Light Green SF Yellowish, through xylem vessels was found to occur when supplied from donor blocks placed acropetally or basipetally. Metabolism of the supplied tryptophan-<span class="hlt">14</span><span class="hlt">C</span> by the tissue segments was shown to occur during the 3 to 6 hour translocation experiments. IAA-<span class="hlt">14</span><span class="hlt">C</span> was transported in a strictly basipetal manner in both tissues. Only 1 labeled compound with an RF value of IAA was found in receiver blocks. Composition of a simple green safelight suitable for work in plant physiology is described. Images PMID:16656664</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>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> </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('https://www.ncbi.nlm.nih.gov/pubmed/19224038','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19224038"><span>The use of multiple probe molecules for the study of the acid-base properties of aluminium hydroxyfluoride having the hexagonal tungsten bronze structure: FTIR and [<span class="hlt">36</span><span class="hlt">Cl</span>] radiotracer studies.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dambournet, Damien; Leclerc, Hervé; Vimont, Alexandre; Lavalley, Jean-Claude; Nickkho-Amiry, Mahmood; Daturi, Marco; Winfield, John M</p> <p>2009-03-07</p> <p>The combination of several probe molecules has enabled the construction of a detailed picture of the surface of aluminium hydroxyl fluoride, AlF(2.6)(OH)(0.4), which has the hexagonal tungsten bronze (HTB) structure. Using pyridine as a probe leads to features at 1628 cm(-1), ascribed to very strong Lewis acid sites, and at 1620-1623 cm(-1), which is the result of several different types of Lewis sites. This heterogeneity is indicated also from CO adsorption at 100 K; the presence of five different types of Lewis site is deduced and is suggested to arise from the hydroxylated environment. Brønsted acid sites of medium strength are indicated by adsorption of lutidine and CO. Adsorption of lutidine occurs at OH groups, which are exposed at the surface and CO reveals that these OH groups have a single environment that can be correlated with their specific location inside the bulk, assuming that the surface OH group may reflect the bulk OH periodicity. A correlation between the data obtained from CO and pyridine molecules has been established using co-adsorption experiments, which also highlight the inductive effect produced by pyridine. Adsorption of the strong Brønsted acid, anhydrous hydrogen chloride, detected by monitoring the beta(-) emission of [(<span class="hlt">36</span>)<span class="hlt">Cl</span>]-HCl at the surface, indicates that surface hydroxyl groups can behave also as a Brønsted base and that H(2)O-HCl interactions, either within the hexagonal channels or at the surface are possible. Finally, the formation of strongly bound H(<span class="hlt">36</span>)<span class="hlt">Cl</span> as a result of the room temperature dehydrochlorination of [(<span class="hlt">36</span>)<span class="hlt">Cl</span>]-labelled tert-butyl chloride provides additional evidence that HTB-AlF(2.6)(OH)(0.4) can behave as a Lewis acid.</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>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('https://www.ncbi.nlm.nih.gov/pubmed/18308434','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18308434"><span><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.ncbi.nlm.nih.gov/pubmed/18283056','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18283056"><span>Low-level occupational <span class="hlt">14</span><span class="hlt">C</span> contamination--results from a pilot study.</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; Leide-Svegborn, Sigrid; Mattsson, Sören</p> <p>2008-01-01</p> <p>This paper presents a pilot study in which specific activities of <span class="hlt">14</span><span class="hlt">C</span> in hair and urine from 11 radiation workers handling <span class="hlt">14</span><span class="hlt">C</span>-containing substances have been measured using accelerator mass spectrometry. Varying degrees of contamination were revealed: up to 63% excess in hair and 400% excess in urine. Although the <span class="hlt">14</span><span class="hlt">C</span> excess reported in this study would result in low effective doses, it would be of interest to monitor the situation at other workplaces with potentially higher risks of contamination. Simultaneous measurements of <span class="hlt">14</span><span class="hlt">C</span> in hair and urine with additional random measurements of <span class="hlt">14</span><span class="hlt">C</span> in faeces and exhaled air could provide a means of improving dose estimates for workers handling different types of <span class="hlt">14</span><span class="hlt">C</span>-containing substances.</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>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://pubs.er.usgs.gov/publication/70094758','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70094758"><span>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/2001QuRes..55..235C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001QuRes..55..235C"><span>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://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Clapp, Erik M.; Bierman, Paul R.; Nichols, Kyle K.; Pavich, Milan; Caffee, Marc</p> <p>2001-03-01</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/2017PalOc..32..123L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PalOc..32..123L"><span>Bulk sediment <span class="hlt">14</span><span class="hlt">C</span> dating in an estuarine environment: How accurate can it be?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lougheed, Bryan C.; Obrochta, Stephen P.; Lenz, Conny; Mellström, Anette; Metcalfe, Brett; Muscheler, Raimund; Reinholdsson, Maja; Snowball, Ian; Zillén, Lovisa</p> <p>2017-02-01</p> <p>Due to a lack of marine macrofossils in many sediment cores from the estuarine Baltic Sea, researchers are often forced to carry out <span class="hlt">14</span><span class="hlt">C</span> determinations on bulk sediment samples. However, ambiguity surrounding the carbon source pathways that contribute to bulk sediment formation introduces a large uncertainty into <span class="hlt">14</span><span class="hlt">C</span> geochronologies based on such samples, and such uncertainty may not have been fully considered in previous Baltic Sea studies. We quantify this uncertainty by analyzing bulk sediment <span class="hlt">14</span><span class="hlt">C</span> determinations carried out on densely spaced intervals in independently dated late-Holocene sediment sequences from two central Baltic Sea cores. Our results show a difference of 600 <span class="hlt">14</span><span class="hlt">C</span> yr in median bulk sediment reservoir age, or R(t)bulk, between the two core locations ( 1200 <span class="hlt">14</span><span class="hlt">C</span> yr for one core, 620 <span class="hlt">14</span><span class="hlt">C</span> yr for the other), indicating large spatial variation. Furthermore, we also find large downcore (i.e., temporal) R(t)bulk variation of at least 200 <span class="hlt">14</span><span class="hlt">C</span> yr for both cores. We also find a difference of 585 <span class="hlt">14</span><span class="hlt">C</span> yr between two samples taken from the same core depth. We propose that studies using bulk sediment <span class="hlt">14</span><span class="hlt">C</span> dating in large brackish water bodies should take such spatiotemporal variation in R(t)bulk into account when assessing uncertainties, thus leading to a larger, but more accurate, calibrated age range.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990PhRvC..42..495H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990PhRvC..42..495H"><span>Possible cluster preformation in the <span class="hlt">14</span><span class="hlt">C</span> decay of 223Ra</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</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 <span class="hlt">14</span><span class="hlt">C</span> fine structure has shown that the branching ratio to 209Pb ground state is quite different from the one predicted by the various models of cluster emission. Assuming that the <span class="hlt">14</span><span class="hlt">C</span> is preformed in the 223Ra nucleus, we have calculated the hindrance factor F<span class="hlt">14</span><span class="hlt">C</span> of the three <span class="hlt">14</span><span class="hlt">C</span> branches to 209Pb states with a barrier penetrability approximated by a square-well Coulomb potential. The F<span class="hlt">14</span><span class="hlt">C</span>=3.9 and 4.6 values found for the <span class="hlt">14</span><span class="hlt">C</span> transitions to the two excited states at 779 keV (Iπ=11/2+) and 1423 keV (Iπ=15/2-), respectively, reveal that the cluster formation amplitudes in both transitions are close to those of the 222Ra and 224Ra <span class="hlt">14</span><span class="hlt">C</span> decays. Such values could be the result of ||nlj> shell-model components common to both the wave functions of the octupole deformed 223Ra nucleus and of the two first excited states of 209Pb spherical nucleus. The high hindrance factor F<span class="hlt">14</span><span class="hlt">C</span>=583 of the <span class="hlt">14</span><span class="hlt">C</span> branch to the 209Pb ground state (Iπ=9/2+) could reveal the absence of ||1g9/2> shell-model component in the 223Ra wave function.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/203607','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/203607"><span>Microbially-mediated fate of {sup <span class="hlt">14</span>}<span class="hlt">C</span>-pyrene in soil organic matter</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Guthroe, E.A.; Pfaender, F.K.</p> <p>1995-12-31</p> <p>Polycyclic aromatic hydrocarbons (PAH) are ubiquitous environmental contaminants that result from both natural and anthropogenic combustion processes. Several microbial processes are known to influence the fate of PAH in soil. Their effect on PAH structure and mobility can affect the potential health risk exposure to humans and indigenous organisms in soil. Microbial metabolism of PAHs can result in the accumulation of more polar by-products or the formation of by-products that may be further metabolized or mineralized by other microorganisms. A third possible fate is the incorporation of PAHs into soil organic matter via various sorption/binding processes. Experiments were conducted to determine the extent of {sup <span class="hlt">14</span>}<span class="hlt">C</span>-pyrene associations with soil organic matter (SOM) in adapted and non-adapted soils. Changes in microbial respiration (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 in aerated soil systems treated individually with 100 mg/kg [4,5,9,10-{sup <span class="hlt">14</span>}<span class="hlt">C</span>] pyrene over time. Mass balances were generated based on V products in water extracts, CO{sub 2} efflux. SOM, {sup <span class="hlt">14</span>}<span class="hlt">C</span>-volatiles, and residual soil. The {sup <span class="hlt">14</span>}<span class="hlt">C</span> products in SOM were further fractionated into humic acids (HA), fulvic acids (FA), and humin. The presence of an adapted, microbial community enhances {sup <span class="hlt">14</span>}<span class="hlt">C</span>-pyrene mineralization and increases the {sup <span class="hlt">14</span>}<span class="hlt">C</span> product accumulation in water extracts and fulvic acids (FA).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001RScI...72..822W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001RScI...72..822W"><span>Study of the 27Al(n,2n)<span class="hlt">26</span><span class="hlt">Al</span> reaction and its potential for ion-temperature measurements (abstract)</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.; Chuvaev, S. V.; Filatenkov, A. A.; Ikeda, Y.; Kutschera, W.; Vonach, H.</p> <p>2001-01-01</p> <p>A detailed measurement of the 27Al(n,2n)<span class="hlt">26</span><span class="hlt">Al</span> reaction cross sections was performed in the near-threshold region (Eth=13.54 MeV), and its possible applicability for ion temperature measurements was investigated. The production of the long-lived radionuclide <span class="hlt">26</span><span class="hlt">Al</span> (t1/2=7.2×105 a) is of considerable interest to the fusion reactor program. Particularly long-lived radionuclides may lead to a significant long-term waste-disposal. Al-containing materials and Si carbide are candidate materials for fusion-reactor systems. The Al(n,2n) reaction and the two step process 28Si(n,np+d)27Al(n,2n) are the dominating processes for the formation of <span class="hlt">26</span><span class="hlt">Al</span> in a fusion reactor.1 The 27Al(n,2n)<span class="hlt">26</span><span class="hlt">Al</span> reaction is expected to vary strongly with neutron energy above threshold. An accurate description of the excitation function is necessary to estimate the production of <span class="hlt">26</span><span class="hlt">Al</span> in a typical D-T fusion environment. From the existing data on cross sections it was not possible to produce an unambiguous excitation function. We started therefore a project to determine this excitation function more accurately. It has been pointed out by Smither and Greenwood2 that the 27Al(n,2n)<span class="hlt">26</span><span class="hlt">Al</span> reaction can be used as a monitor to determine the ion temperature in a D-T fusion plasma. This method makes use of the neutron energy distribution as a sensitive function of the plasma ion temperature. The temperature sensitivity is most pronounced if the excitation function is strongly nonlinear and if the threshold falls within the energy region of the emitted neutrons: For the 27Al(n,2n)<span class="hlt">26</span><span class="hlt">Al</span> reaction the threshold lies at 13.54 MeV and the (n,2n) reaction is expected to a strongly varying function of the neutron energy near threshold. Al samples were irradiated with 14 MeV neutrons generated via the T(d,n)4He reaction at three different laboratories under different conditions. The produced <span class="hlt">26</span><span class="hlt">Al</span> was measured using the extremely sensitive method of accelerator mass spectrometry (AMS). <span class="hlt">26</span><span class="hlt">Al</span>/27Al isotope ratios as low as</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>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('https://www.ncbi.nlm.nih.gov/pubmed/24284990','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24284990"><span>Evaluation of the (<span class="hlt">14</span>)<span class="hlt">C</span>-urea breath test using indigenously produced (<span class="hlt">14</span>)<span class="hlt">C</span>-urea capsules and a modified technique for trapping exhaled breath: a pilot study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tiwari, Bijaynath P; Nistala, Srinivas; Patil, Sanjay P; Kalgutkar, Deepak P; Jaychandran, Narath; Chander, Harish; Basu, Sandip</p> <p>2014-03-01</p> <p>The carbon urea breath test ((<span class="hlt">14</span>)<span class="hlt">C</span>-UBT) is a noninvasive technique used to detect Helicobacter pylori infection in patients presenting with dyspeptic symptoms. The present study was undertaken to determine the efficacy of indigenously produced (<span class="hlt">14</span>)<span class="hlt">C</span>-UBT capsules by the Board of Radiation and Isotope Technology, India. Thirty consecutive patients with dyspeptic symptoms were included in the study. After ingestion of capsules, breath samples were collected in a CO2-trapping solution to which a scintillation cocktail was added. After 24 h, the whole sample was counted in a liquid scintillation counter along with a standard of (<span class="hlt">14</span>)<span class="hlt">C</span>. The number of disintegrations of (<span class="hlt">14</span>)<span class="hlt">C</span> per minute in the breath sample was calculated. The results were compared with histopathological reports. Of 30 patients, 19 were positive and 11 were negative on (<span class="hlt">14</span>)<span class="hlt">C</span>-UBT. Histopathological reports confirmed 27 cases as positive and three as negative for H. pylori. Thus, the results of (<span class="hlt">14</span>)<span class="hlt">C</span>-UBT were concordant with histopathological results in 22/30 (73.3%) cases. Considering histopathology as the gold standard, the sensitivity, specificity, and positive predictive value of (<span class="hlt">14</span>)<span class="hlt">C</span>-UBT using indigenously produced capsules were found to be 70.33, 100, and 100%, respectively. On critical analysis of the discordant results, we observed that six patients had undergone H. pylori eradication therapy exactly 4 weeks before the test. When these six patients were excluded from the analysis, the sensitivity, specificity, and positive predictive value were found to be 90.05, 100, and 100%, respectively, which compared well with the values obtained using the standard procedure. The study demonstrates adequate efficacy of the indigenous methodology in newly diagnosed symptomatic patients with acid peptic disorders. The analyses of the results indicate that the test should be preferably employed after the recommended period of 1 month following completion of eradication therapy.</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>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('https://www.osti.gov/scitech/biblio/21254838','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21254838"><span>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('https://www.gpo.gov/fdsys/pkg/CFR-2010-title17-vol3/pdf/CFR-2010-title17-vol3-sec240-14c-4.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title17-vol3/pdf/CFR-2010-title17-vol3-sec240-14c-4.pdf"><span>17 CFR 240.<span class="hlt">14</span><span class="hlt">c</span>-4 - Presentation of information in information statement.</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>... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Presentation of information in... Section <span class="hlt">14</span>(<span class="hlt">c</span>) § 240.<span class="hlt">14</span><span class="hlt">c</span>-4 Presentation of information in information statement. (a) The information... type except that to the extent necessary for convenient presentation, financial statements and...</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>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>... 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... Availability of Proxy Materials, annual report to security holders or information statement, as applicable. (d... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Annual report to be...</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-7.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title17-vol3/pdf/CFR-2010-title17-vol3-sec240-14c-7.pdf"><span>17 CFR 240.<span class="hlt">14</span><span class="hlt">c</span>-7 - Providing copies of material for certain beneficial owners.</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>... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Providing copies of material for certain beneficial owners. 240.<span class="hlt">14</span><span class="hlt">c</span>-7 Section 240.<span class="hlt">14</span><span class="hlt">c</span>-7 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED) GENERAL RULES AND REGULATIONS, SECURITIES EXCHANGE ACT OF...</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-2.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title17-vol3/pdf/CFR-2010-title17-vol3-sec240-14c-2.pdf"><span>17 CFR 240.<span class="hlt">14</span><span class="hlt">c</span>-2 - Distribution of information statement.</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>... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Distribution of information statement. 240.<span class="hlt">14</span><span class="hlt">c</span>-2 Section 240.<span class="hlt">14</span><span class="hlt">c</span>-2 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED) GENERAL RULES AND REGULATIONS, SECURITIES EXCHANGE ACT OF 1934 Rules and Regulations Under...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=315047','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=315047"><span><span class="hlt">14</span><span class="hlt">C</span> Incorporation into the Fatty Acids and Aliphatic Hydrocarbons of Sarcina lutea</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Tornabene, T. G.; Oró, J.</p> <p>1967-01-01</p> <p>An initial investigation into the mechanism of hydrocarbon biosynthesis in Sarcina lutea was performed by measuring the amounts of <span class="hlt">14</span><span class="hlt">C</span> incorporated into the hydrocarbons and fatty acids by use of a combination gas chromatograph and high-temperature gas-flow ionization apparatus. Uniformly labeled l-isoleucine-<span class="hlt">14</span><span class="hlt">C</span> was predominantly incorporated into the anteiso-branched chains. Palmitate-16-<span class="hlt">14</span><span class="hlt">C</span> gave evidence that a direct correlation may exist between the nonpolar end of the palmitate and the biosynthesis of hydrocarbons and carotenoids. The label from palmitate-1-<span class="hlt">14</span><span class="hlt">C</span> was incorporated into the various hydrocarbon groups as a compound, derived from the polar end of the palmitate, consisting of more than two carbon atoms. Palmitate-16-<span class="hlt">14</span><span class="hlt">C</span> and -1-<span class="hlt">14</span><span class="hlt">C</span> gave no detectable evidence that transformed products were incorporated into other fatty acids. Sodium acetate-2-<span class="hlt">14</span><span class="hlt">C</span> and uniformly labeled l-leucine-<span class="hlt">14</span><span class="hlt">C</span> gave evidence of a nonspecific incorporation into both the aliphatic hydrocarbons and fatty acids of Sarcina lutea. PMID:6039358</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://adsabs.harvard.edu/abs/2012GeCoA..77..415B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012GeCoA..77..415B"><span><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><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('https://www.osti.gov/scitech/biblio/6880284','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6880284"><span>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/25288281','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25288281"><span>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="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yin, Jinhui; Yang, Xue; Zheng, Yonggang</p> <p>2014-10-07</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>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990JCHyd...5..133K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990JCHyd...5..133K"><span>An approximate calculation of advective gas-phase transport of <span class="hlt">14</span><span class="hlt">C</span> at Yucca Mountain, Nevada</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Knapp, R. B.</p> <p>1990-01-01</p> <p>A quasilinear partial differential equation, which describes gas-phase transport of a <span class="hlt">14</span><span class="hlt">C</span> kinematic wave through a porous medium, is derived, its sensitivity to system variables is analyzed and it is applied to one possible release scenarion at the porposed Yucca Mountain, Nevada high-level radioactive waste repository. Advection, isotope exchange between CO 2 in a flowing gas phase and HCO 3- in a static aqueous phase, and radioactive decay are incorporated. The governing equation is solved analytically by the method of characteristics. The mass fraction of <span class="hlt">14</span><span class="hlt">C</span> in the gas phase,X 14g, is controlled by radioactive decay. The relatively long half-line of <span class="hlt">14</span><span class="hlt">C</span>, about 5720 years, and the relatively shallow proposed burial depth of the radioactive waste, about 350m, requires significant retardation of the <span class="hlt">14</span><span class="hlt">C</span> wave velocity for significant reduction in X 14g. <span class="hlt">14</span><span class="hlt">C</span> wave velocity is most sensitive to temperature and pH which control the distribution of total carbon between gas and liquid phase; the greater the partitioning of carbon into the liquid phase, the greater the retardation of the <span class="hlt">14</span><span class="hlt">C</span> wave velocity and the greater the ultimate reduction in X 14g from initial conditions. Partitioning of total carbon into the liquid phase is greatest at low temperatures, < 100° C, and high pH values, > 8. Increasing water saturation also tends to retard <span class="hlt">14</span><span class="hlt">C</span> wave velocity but to a lesser extent. The governing equation has been applied using conditions that may possibly occur at the proposed Yucca Mountain repository. Calculations indicate that the <span class="hlt">14</span><span class="hlt">C</span> wave takes about 5900 years to reach the surface with a X 14g equal to 25 ppm. Diffusion and dispersion are not of major importance for these conditions. These calculations are approximate due to the number of assumptions involved. Discharge of <span class="hlt">14</span><span class="hlt">C</span> into the gas before the selected time would accelerate wave arrival and increase the amount of <span class="hlt">14</span><span class="hlt">C</span> reaching the surface.</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>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('https://www.ncbi.nlm.nih.gov/pubmed/28100493','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28100493"><span>Large <span class="hlt">14</span><span class="hlt">C</span> excursion in 5480 BC indicates an abnormal sun in the mid-Holocene.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Miyake, Fusa; Jull, A J Timothy; Panyushkina, Irina P; Wacker, Lukas; Salzer, Matthew; Baisan, Christopher H; Lange, Todd; Cruz, Richard; Masuda, Kimiaki; Nakamura, Toshio</p> <p>2017-01-31</p> <p>Radiocarbon content in tree rings can be an excellent proxy of the past incoming cosmic ray intensities to Earth. Although such past cosmic ray variations have been studied by measurements of (<span class="hlt">14</span>)<span class="hlt">C</span> contents in tree rings with ≥10-y time resolution for the Holocene, there are few annual (<span class="hlt">14</span>)<span class="hlt">C</span> data. There is a little understanding about annual (<span class="hlt">14</span>)<span class="hlt">C</span> variations in the past, with the exception of a few periods including the AD 774-775 (<span class="hlt">14</span>)<span class="hlt">C</span> excursion where annual measurements have been performed. Here, we report the result of (<span class="hlt">14</span>)<span class="hlt">C</span> measurements using the bristlecone pine tree rings for the period from 5490 BC to 5411 BC with 1- to 2-y resolution, and a finding of an extraordinarily large (<span class="hlt">14</span>)<span class="hlt">C</span> increase (20‰) from 5481 BC to 5471 BC (the 5480 BC event). The (<span class="hlt">14</span>)<span class="hlt">C</span> increase rate of this event is much larger than that of the normal grand solar minima. We propose the possible causes of this event are an unknown phase of grand solar minimum, or a combination of successive solar proton events and a normal grand solar minimum.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PNAS..114..881M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PNAS..114..881M"><span>Large <span class="hlt">14</span><span class="hlt">C</span> excursion in 5480 BC indicates an abnormal sun in the mid-Holocene</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Miyake, Fusa; Jull, A. J. Timothy; Panyushkina, Irina P.; Wacker, Lukas; Salzer, Matthew; Baisan, Christopher H.; Lange, Todd; Cruz, Richard; Masuda, Kimiaki; Nakamura, Toshio</p> <p>2017-01-01</p> <p>Radiocarbon content in tree rings can be an excellent proxy of the past incoming cosmic ray intensities to Earth. Although such past cosmic ray variations have been studied by measurements of <span class="hlt">14</span><span class="hlt">C</span> contents in tree rings with ≥10-y time resolution for the Holocene, there are few annual <span class="hlt">14</span><span class="hlt">C</span> data. There is a little understanding about annual <span class="hlt">14</span><span class="hlt">C</span> variations in the past, with the exception of a few periods including the AD 774‑775 <span class="hlt">14</span><span class="hlt">C</span> excursion where annual measurements have been performed. Here, we report the result of <span class="hlt">14</span><span class="hlt">C</span> measurements using the bristlecone pine tree rings for the period from 5490 BC to 5411 BC with 1- to 2-y resolution, and a finding of an extraordinarily large <span class="hlt">14</span><span class="hlt">C</span> increase (20‰) from 5481 BC to 5471 BC (the 5480 BC event). The <span class="hlt">14</span><span class="hlt">C</span> increase rate of this event is much larger than that of the normal grand solar minima. We propose the possible causes of this event are an unknown phase of grand solar minimum, or a combination of successive solar proton events and a normal grand solar minimum.</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>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://adsabs.harvard.edu/abs/2001AIPC..576..394M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AIPC..576..394M"><span>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.osti.gov/scitech/biblio/5186780','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5186780"><span>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/2015AGUFM.V31G..09C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.V31G..09C"><span>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.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=396159','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=396159"><span>Metabolism of <span class="hlt">14</span><span class="hlt">C</span>-Maltose in Avena fatua Seeds During Germination 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>Chen, Shepley S. C.; Varner, J. E.</p> <p>1969-01-01</p> <p>Non-dormant and dormant seeds of Avena fatua metabolize <span class="hlt">14</span><span class="hlt">C</span>-maltose in different ways: in non-dormant seeds, <span class="hlt">14</span><span class="hlt">C</span>-maltose administered to the endosperm is readily converted to sucrose in the scutellum and translocated to the embryo; in dormant seeds, little sucrose is synthesized from <span class="hlt">14</span><span class="hlt">C</span>-maltose, and maltose and glucose tend to accumulate in the endosperm. It is suggested that biosynthesis of sucrose is essential for effective transport of the endosperm reserve to the embryonic axis in germinating seeds. PMID:16657130</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27450755','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27450755"><span>Mineralisation of (<span class="hlt">14</span>)<span class="hlt">C</span>-labelled polystyrene plastics by Penicillium variabile after ozonation pre-treatment.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tian, Lili; Kolvenbach, Boris; Corvini, Nora; Wang, Songfeng; Tavanaie, Nasrin; Wang, Lianhong; Ma, Yini; Scheu, Stefan; Corvini, Philippe François-Xavier; Ji, Rong</p> <p>2016-07-19</p> <p>Large amounts of polystyrene (PS), one of the most widely used plastics in the world, end up in the environment through industrial discharge and littering, becoming one of the major components of plastic debris. Such plastics, especially the small-sized microplastics and nanoplastics, have received increasing concerns in terms of their potential environmental risks. Feasible approaches for the degradation of PS in waste materials and in the environment are highly desirable. Physicochemical pretreatments of PS may be applied to enhance biological degradation. In the present study, we synthesized (<span class="hlt">14</span>)<span class="hlt">C</span>-labelled PS polymers, either uniformly labelled on the ring ([U-ring-(<span class="hlt">14</span>)<span class="hlt">C</span>]-PS) or labelled at the β-carbon position of the alkyl chain ([β-(<span class="hlt">14</span>)<span class="hlt">C</span>]-PS), and investigated the mineralisation of the (<span class="hlt">14</span>)<span class="hlt">C</span>-PS polymers by the fungus Penicillium variabile CCF3219 as well as the effect of ozonation as a physico-chemical pre-treatment on the mineralisation by the fungi. Biodegradation of the (<span class="hlt">14</span>)<span class="hlt">C</span>-PS polymers was studied in liquid medium (pH 7.5, without additional carbon substrate) with P. variabile for 16 weeks. During the incubation time, (14)CO2 was captured to calculate the mineralisation of (<span class="hlt">14</span>)<span class="hlt">C</span>-PS and the remaining polymers were analysed by means of scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectrometry and gel-permeation chromatography (GPC). The results showed that the fungi mineralised both labelled polymers, and that the [U-ring-(<span class="hlt">14</span>)<span class="hlt">C</span>]-PS with a lower molecular weight led to a higher mineralisation rate. Ozonation pre-treatment strongly enhanced mineralisation of [β-(<span class="hlt">14</span>)<span class="hlt">C</span>]-PS. SEM analysis showed that the surface of the ozonated [β-(<span class="hlt">14</span>)<span class="hlt">C</span>]-PS became uneven and rough after the incubation, indicating an attack on the polymer by P. variabile. FT-IR analysis showed that ozonation generated carbonyl groups on the [β-(<span class="hlt">14</span>)<span class="hlt">C</span>]-PS and the amount of the carbonyl groups decreased after incubation of the [β-(<span class="hlt">14</span>)<span class="hlt">C</span>]-PS with P. variabile. GPC</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>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('https://www.ncbi.nlm.nih.gov/pubmed/26585641','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26585641"><span>Comparison of (<span class="hlt">14</span>)<span class="hlt">C</span> liquid scintillation counting at NIST and NRC Canada.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bergeron, Denis E; Galea, Raphael; Laureano-Pérez, Lizbeth; Zimmerman, Brian E</p> <p>2016-03-01</p> <p>An informal bilateral comparison of (<span class="hlt">14</span>)<span class="hlt">C</span> liquid scintillation (LS) counting at the National Research Council of Canada (NRC) and the National Institute of Standards and Technology (NIST) has been completed. Two solutions, one containing (<span class="hlt">14</span>)<span class="hlt">C</span>-labeled sodium benzoate and one containing (<span class="hlt">14</span>)<span class="hlt">C</span>-labeled n-hexadecane, were measured at both laboratories. Despite observed LS cocktail instabilities, the two laboratories achieved accord in their standardizations of both solutions. At the conclusion of the comparison, the beta spectrum used for efficiency calculations was identified as inadequate and the data were reanalyzed with different inputs, improving accord.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20863750','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20863750"><span>Measurement of {sup 25}Mg(p, {gamma}){sup <span class="hlt">26</span>}<span class="hlt">Al</span>{sup g} resonance strengths via accelerator mass spectrometry</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Arazi, A.; Niello, J. O. Fernandez; Faestermann, T.; Knie, K.; Korschinek, G.; Poutivtsev, M.; Rugel, G.; Richter, E.; Wallner, A.</p> <p>2006-08-15</p> <p>The strengths of resonances located at center-of-mass energies of E{sub c.m.}=189, 304, 374, and 418 keV for the {sup 25}Mg(p,{gamma}) reaction have been measured for the first time with an off-line method: Mg targets were firstly activated with protons at the resonance energies and the produced {sup <span class="hlt">26</span>}<span class="hlt">Al</span>{sup g} nuclei were counted by means of highly sensitive accelerator mass spectrometry (AMS). Thus, the production of {sup <span class="hlt">26</span>}<span class="hlt">Al</span> in its ground state is determined independently from the {gamma}-decay branching ratio. While the 304, 374, and 418 keV resonances show fair agreement with previous measurements, the 189 keV resonance yield a significantly less strength. In addition, an experimental upper limit for the E{sub c.m.}=92 keV resonance was determined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6240543','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6240543"><span>Distribution of /sup <span class="hlt">14</span>/<span class="hlt">C</span> after oral administration of (1-/sup <span class="hlt">14</span>/<span class="hlt">C</span>)linoleic acid in rats fed different levels of essential fatty acids</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Becker, W.</p> <p>1984-09-01</p> <p>Rats from an inbred Sprague-Dawley strain were fed semisynthetic diets with a low (0.3 energy percent (en %)), normal (3 en %) or high (10 en %) content of essential fatty acids (EFA) for at least three generations. Twenty-nine- to 33-day-old male rats were given a single intragastric dose of (1-<span class="hlt">14</span><span class="hlt">C</span>)linoleic acid in olive oil, and the respiratory CO2, urine and feces were collected for 46 hours (expt 1) or 20 hours (expt 2). The <span class="hlt">14</span><span class="hlt">C</span> activity in respiratory CO2, feces, urine and the carcass was determined in both experiments. In experiment 2 it was also measured in samples of the brown fat, liver, adrenals, white fat, skeletal muscles and brain. In both experiments the rats fed the low EFA diet retained significantly more <span class="hlt">14</span><span class="hlt">C</span> activity than the rats fed the normal or high EFA diets. In all groups the concentration of label was highest in the brown fat and the adrenals, but the above differences among the groups with respect to <span class="hlt">14</span><span class="hlt">C</span> retention were mainly observed in the liver, skeletal muscles and brain.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26492342','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26492342"><span>Impact of liming and drying municipal sewage sludge on the amount and availability of (<span class="hlt">14</span>)<span class="hlt">C</span>-acetyl sulfamethoxazole and (<span class="hlt">14</span>)<span class="hlt">C</span>-acetaminophen residues.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Geng, Chunnu; Bergheaud, Valérie; Garnier, Patricia; Zhu, Yong-Guan; Haudin, Claire-Sophie</p> <p>2016-01-01</p> <p>Acetyl Sulfamethoxazole (AC-SMX) and acetaminophen (ACM) can be found in municipal sewage sludge, and their content and availability may be influenced by sludge treatments, such as drying and liming. A sludge similarly centrifuged with/without a flocculant was spiked with (<span class="hlt">14</span>)<span class="hlt">C</span>-labelled AC-SMX or ACM. Then, it was either limed (20% CaO) or/and dried under different laboratory conditions (1 week at ambient temperature; and 48 h at 40 or 80 °C). The total amount and distribution of the (<span class="hlt">14</span>)<span class="hlt">C</span>-compounds among several chemical fractions, based on the sludge floc definition, were assessed at the end of the treatments. All the (<span class="hlt">14</span>)<span class="hlt">C</span>-activity brought initially was recovered in the limed and/or dried sludges for AC-SMX but only between 44.4 and 84.9% for ACM, with the highest rate obtained for the limed sludge. Drying at 80 °C or liming increased the percentage of the sludge total organic carbon recovered in the extracts containing soluble extracellular polymeric substances (S-EPS) and the percentage of the total (<span class="hlt">14</span>)<span class="hlt">C</span>-activity extracted simultaneously. The non-extractable residues represented only 3.9-11.6% of the total (<span class="hlt">14</span>)<span class="hlt">C</span>-activity measured in the treated sludges for AC-SMX and 16.9-21.8% for ACM. The presence of AC-SMX and ACM residues in the treated sludges, after liming and drying under different conditions, was shown using some (<span class="hlt">14</span>)<span class="hlt">C</span>-labelled molecules. At this time scale and according to the extraction method selected, most of the (<span class="hlt">14</span>)<span class="hlt">C</span>-residues remained soluble and easily extractable for both compounds. This result implies that certain precautions should be taken when storing sludges before being spread on the field. Sludge piles, particularly the limed sludge, should be protected from rain to limit the production of lixiviates, which may contain residues of AC-SMX and ACM.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22372379','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22372379"><span>Penetrative and dislodgeable residue characteristics of <span class="hlt">14</span><span class="hlt">C</span>-insecticides in apple fruit.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mota-Sanchez, David; Cregg, Bert; Hoffmann, Eric; Flore, James; Wise, John C</p> <p>2012-03-28</p> <p>Infinite- and finite-dose laboratory experiments were used to study the penetrative and dislodgeable residue characteristics of (<span class="hlt">14</span>)<span class="hlt">C</span>-insecticides in apple fruit. The differences in dislodgeable and penetrated residues of three radiolabeled insecticides ((<span class="hlt">14</span>)<span class="hlt">C</span>-thiamethoxam, (<span class="hlt">14</span>)<span class="hlt">C</span>-thiacloprid, and (<span class="hlt">14</span>)<span class="hlt">C</span>-indoxacarb), applied in aqueous solution with commercial formulations, were determined after water and methanol wash extractions. The rate of sorption and extent of penetration into the fruit cuticles and hypanthium of two apple cultivars were measured after 1, 6, and 24 h of treatment exposure, using radioactivity quantification methods. For all three compounds, 97% or more of the treatment solutions were found on the fruit surface as some form of non-sorbed residues. For indoxacarb, sorption into the epicuticle was rapid but desorption into the fruit hypanthium was delayed, indicative of a lipophilic penetration pathway. For the neonicotinoids, initial cuticular penetration was slower but with no such delay in desorption into the hypanthium.</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('https://www.osti.gov/scitech/biblio/6867649','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6867649"><span>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('http://adsabs.harvard.edu/abs/1994ZPhyA.349..311H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994ZPhyA.349..311H"><span><span class="hlt">14</span><span class="hlt">C</span> cluster emission: a tool for the study of nuclear structures</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hussonnois, M.; Ardisson, G.</p> <p>1994-09-01</p> <p>A brief survey of the<span class="hlt">14</span><span class="hlt">C</span> cluster emission of different radium isotopes will remind the first evidence for an odd-even effect in<span class="hlt">14</span><span class="hlt">C</span> radioactivity. The discovery at the I.P.N. Orsay, of a fine structure in the<span class="hlt">14</span><span class="hlt">C</span> emission of223Ra enhanced the development of this new investigation field. The qualitative interpretation of the favoured transitions to the first two excited states of the209Pb daughter nucleus offers a new possibility to better understand nuclear structures of heavy deformed nuclei. For instance, an accurate determination of the energy of the<span class="hlt">14</span><span class="hlt">C</span> clusters emitted by225Ac and221Fr must allow to improve our knowledge of ground state configurations of these nuclei.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1991PhRvC..43.2599H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1991PhRvC..43.2599H"><span>Search for a fine structure in the <span class="hlt">14</span><span class="hlt">C</span> decay of 222Ra</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hussonnois, M.; Le Du, J. F.; Brillard, L.; Dalmasso, J.; Ardisson, G.</p> <p>1991-06-01</p> <p>The <span class="hlt">14</span><span class="hlt">C</span> decay of 222Ra has been reinvestigated, using an 85 MBq activity 230U source radiochemically separated, a Si barrier detector, and a superconducting magnetic spectrometer. In a 16 days counting run, 210 <span class="hlt">14</span><span class="hlt">C</span> events were recorded. The <span class="hlt">14</span><span class="hlt">C</span> particles energy value 30.930+/-0.090 MeV was found and an upper limit b<=2×10-12 was estimated for the <span class="hlt">14</span><span class="hlt">C</span> branching ratio to the 208Pb first excited state; the branching-ratio value to the 208Pb ground state, thus equal to the total branching ratio, was found to be b=λc/λα=(2.31+/-0.31)×10-10.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMPP21B1798S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMPP21B1798S"><span>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('https://www.osti.gov/scitech/biblio/6648487','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6648487"><span>( 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://www.osti.gov/scitech/servlets/purl/972404','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/972404"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/19702837','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19702837"><span>Constraining carbon sources and growth rates of freshwater microbialites in Pavilion Lake using (<span class="hlt">14</span>)<span class="hlt">C</span> analysis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Brady, A L; Slater, G; Laval, B; Lim, D S</p> <p>2009-12-01</p> <p>This study determined the natural abundance isotopic compositions ((13)C, (<span class="hlt">14</span>)<span class="hlt">C</span>) of the primary carbon pools and microbial communities associated with modern freshwater microbialites located in Pavilion Lake, British Columbia, Canada. The Delta(<span class="hlt">14</span>)<span class="hlt">C</span> of dissolved inorganic carbon (DIC) was constant throughout the water column and consistent with a primarily atmospheric source. Observed depletions in DIC (<span class="hlt">14</span>)<span class="hlt">C</span> values compared with atmospheric CO(2) indicated effects due either to DIC residence time and/or inputs of (<span class="hlt">14</span>)<span class="hlt">C</span>-depleted groundwater. Mass balance comparisons of local and regional groundwater indicate that groundwater DIC could contribute a maximum of 9-13% of the DIC. (<span class="hlt">14</span>)<span class="hlt">C</span> analysis of microbial phospholipid fatty acids from microbialite communities had Delta(<span class="hlt">14</span>)<span class="hlt">C</span> values comparable with lake water DIC, demonstrating that lake water DIC was their primary carbon source. Microbialite carbonate was also primarily derived from DIC. However, some depletion in microbialite carbonate (<span class="hlt">14</span>)<span class="hlt">C</span> relative to lake water DIC occurred, due either to residence time or mixing with a (<span class="hlt">14</span>)<span class="hlt">C</span>-depleted carbon source. A detrital branch covered with microbialite growth was used to estimate a microbialite growth rate of 0.05 mm year(-1) for the past 1000 years, faster than previous estimates for this system. These results demonstrate that the microbialites are actively growing and that the primary carbon source for both microbial communities and recent carbonate is DIC originating from the atmosphere. While these data cannot conclusively differentiate between abiotic and biotic formation mechanisms, the evidence for minor inputs of groundwater-derived DIC is consistent with the previously hypothesized biological origin of the Pavilion Lake microbialites.</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>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>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('http://adsabs.harvard.edu/abs/2017GGG....18..142V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GGG....18..142V"><span>Short organic carbon turnover time and narrow <span class="hlt">14</span><span class="hlt">C</span> age spectra in early Holocene wetland paleosols</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vetter, Lael; Rosenheim, Brad E.; Fernandez, Alvaro; Törnqvist, Torbjörn E.</p> <p>2017-01-01</p> <p>Paleosols contain information about the rates of soil organic carbon turnover when the soil was actively forming. However, this temporal information is often difficult to interpret without tight stratigraphic control on the age of the paleosol. Here we apply ramped pyrolysis/oxidation (Ramped PyrOx) <span class="hlt">14</span><span class="hlt">C</span> analyses to evaluate age spectra of transgressive early Holocene paleosols from the Mississippi Delta in southeastern Louisiana, USA. We find <span class="hlt">14</span><span class="hlt">C</span> age spectra from soil organic matter (SOM) in both paleosols and overlying basal peats that represent variability in age that is close to, or only slightly greater than, analytical uncertainty of <span class="hlt">14</span><span class="hlt">C</span> measurements, despite different sources of carbon with likely disparate ages. Such age spectra have not previously been observed in the sedimentary record. Here they indicate vigorous soil carbon turnover prior to burial, which homogenized <span class="hlt">14</span><span class="hlt">C</span> ages within SOM across the entire thermochemical spectrum. The weighted bulk <span class="hlt">14</span><span class="hlt">C</span> ages from Ramped PyrOx of paleosols and overlying peats are identical within analytical and process-associated uncertainty, and corroborate <span class="hlt">14</span><span class="hlt">C</span> ages from charcoal fragments and plant macrofossils from the overlying peat. The youngest ages from Ramped PyrOx age spectra may also potentially be applied as chronometers for stratigraphic burial ages. Our results suggest rapid turnover (≪300 years) of carbon in these soils relative to input of allochthonous carbon, indicating that the <span class="hlt">14</span><span class="hlt">C</span> age of different soil components is decoupled from thermochemical stability and instead reflects vigorous turnover processes. The concurrence of paleosol and peat <span class="hlt">14</span><span class="hlt">C</span> ages also suggests that pedogenic processes were linked with the development of coastal marshes, and that the priming effect potentially masked the signal of allochthonous carbon inputs during sea level rise.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/1359552','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/1359552"><span>[<span class="hlt">14</span><span class="hlt">C</span>]deoxyglucose labelling of functional activity in the cephalopod central nervous system.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Novicki, A; Messenger, J B; Budelmann, B U; Terrell, M L; Kadekaro, M</p> <p>1992-07-22</p> <p>For the first time, the [<span class="hlt">14</span><span class="hlt">C</span>]deoxyglucose radioautographic technique has been successfully used to map physiological activity in cephalopod brains. In unilaterally blinded octopus and cuttlefish, the optic lobe of the deprived side showed a decreased uptake of the labelled tracer. This suggests that the uptake is related to functional activity. The potential of the [<span class="hlt">14</span><span class="hlt">C</span>]deoxyglucose technique as a powerful tool in studying the functional organization of cephalopod brains is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001EPJA...12..383G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001EPJA...12..383G"><span>New measurement of exotic decay of 225Ac by <span class="hlt">14</span><span class="hlt">C</span> emission</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guglielmetti, A.; Bonetti, R.; Ardisson, G.; Barci, V.; Giles, T.; Hussonnois, M.; Le Du, J. F.; Le Naour, C.; Mikheev, V. L.; Pasinetti, A. L.; Ravn, H. L.; Tretyakova, S. P.; Trubert, D.</p> <p></p> <p>The branching ratio of 225Ac decay by emission of <span class="hlt">14</span><span class="hlt">C</span> was remeasured under improved experimental conditions by using a radioactive source produced at the ISOLDE mass-separator at CERN and a nuclear track detector technique. The result, B = λ<span class="hlt">14</span><span class="hlt">C</span>/λα = (4.5+/-1.4)10-12, is consistent with the anomalously high value obtained in the 1993 experiment, thus confirming the importance of nuclear-structure effects in this exotic decay.</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>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/14708776','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14708776"><span>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/23626987','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23626987"><span>Biological and biomedical (<span class="hlt">14</span>)<span class="hlt">C</span>-accelerator mass spectrometry and graphitization of carbonaceous samples.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chung, Ill-Min; Kim, Seung-Hyun</p> <p>2013-06-21</p> <p>Accelerator mass spectrometry (AMS) is the ultimate technique for measuring rare isotopes in small samples. Biological and biomedical applications of (<span class="hlt">14</span>)<span class="hlt">C</span>-AMS (bio-(<span class="hlt">14</span>)<span class="hlt">C</span>-AMS) commenced in the early 1990s and are now widely used in many research fields including pharmacology, toxicology, food, and nutrition. For accurate, precise, and reproducible bio-(<span class="hlt">14</span>)<span class="hlt">C</span>-AMS analysis, the graphitization step in sample preparation is the most critical step. So, various sample preparation methods for a process called graphitization have been reported for specific applications. Catalytic graphitization using either a flame-sealed borosilicate tube or a septa-sealed vial is a popular sample preparation method for bio-(<span class="hlt">14</span>)<span class="hlt">C</span>-AMS. In this review, we introduce the AMS system, especially for bio-(<span class="hlt">14</span>)<span class="hlt">C</span>-AMS. In addition, we also review the graphitization method for bio-(<span class="hlt">14</span>)<span class="hlt">C</span>-AMS to promote further understanding and improvement of sample preparation for this technique. Examples of catalytic graphitization methods over the past two decades are described.</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>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.osti.gov/scitech/biblio/5643929','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5643929"><span>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>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('https://www.osti.gov/scitech/biblio/6787784','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6787784"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/19698709','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19698709"><span>Quantitative and regional measurement of retinal blood flow in rats using N-isopropyl-p-[<span class="hlt">14</span><span class="hlt">C</span>]-iodoamphetamine ([<span class="hlt">14</span><span class="hlt">C</span>]-IMP).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pouliot, Mylène; Deschênes, Micheline C; Hétu, Simon; Chemtob, Sylvain; Lesk, Mark R; Couture, Réjean; Vaucher, Elvire</p> <p>2009-12-01</p> <p>Quantitative and regional measurement of retinal blood flow in rodents is of prime interest for the investigation of regulatory mechanisms of ocular circulation in physiological and pathological conditions. In this study, a quantitative autoradiographic method using N-isopropyl-p-(<span class="hlt">14</span>)<span class="hlt">C</span>-iodoamphetamine ([(<span class="hlt">14</span>)<span class="hlt">C</span>]-IMP), a diffusible radioactive tracer, was evaluated for its ability to detect changes in retinal blood perfusion during hypercapnia. Findings were compared to cerebral blood flow values measured simultaneously. Hypercapnia was induced in awaken Wistar rats by inhalation of 5% or 8% CO(2) in medical air for 5 min. [(<span class="hlt">14</span>)<span class="hlt">C</span>]-IMP (100 microCi/kg) was injected in the femoral vein over a 30 s period and the rats were sacrificed 2 min later. Blood flow was calculated from whole-mount retinae and 20 microm thick brain sections in discrete regions of interest by quantitative autoradiography or from digested samples of retina and brain by liquid scintillation counting. Retinal blood flow values measured with quantitative and regional autoradiography were higher in the central (108 +/- 20 ml/100 g/min) than in peripheral (84 +/- 15 ml/100 g/min) retina. These values were within the same range as cortical blood flow values (97 +/- 4 ml/100 g/min). The retinal blood flow values obtained on whole-mount retinae were validated by the sampling method. Hypercapnia significantly increased overall blood flow in the retina (24-53%) with a maximal augmentation in the peripheral region and in the brain (22-142%). The changes were stronger in the brain compared to retina (p = 0.016). These results demonstrate that retinal blood flow can be quantified using [(<span class="hlt">14</span>)<span class="hlt">C</span>]-IMP and compared with cerebral blood flow. This technique is a powerful tool to study how retinal blood flow is regulated in different regions of the rat retina.</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/2015NIMPB.361..381L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NIMPB.361..381L"><span>Progress in automated extraction and purification of in situ <span class="hlt">14</span><span class="hlt">C</span> from quartz: Results from the Purdue in situ <span class="hlt">14</span><span class="hlt">C</span> laboratory</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lifton, Nathaniel; Goehring, Brent; Wilson, Jim; Kubley, Thomas; Caffee, Marc</p> <p>2015-10-01</p> <p>Current extraction methods for in situ <span class="hlt">14</span><span class="hlt">C</span> from quartz [e.g., Lifton et al., (2001), Pigati et al., (2010), Hippe et al., (2013)] are time-consuming and repetitive, making them an attractive target for automation. We report on the status of in situ <span class="hlt">14</span><span class="hlt">C</span> extraction and purification systems originally automated at the University of Arizona that have now been reconstructed and upgraded at the Purdue Rare Isotope Measurement Laboratory (PRIME Lab). The Purdue in situ <span class="hlt">14</span><span class="hlt">C</span> laboratory builds on the flow-through extraction system design of Pigati et al. (2010), automating most of the procedure by retrofitting existing valves with external servo-controlled actuators, regulating the pressure of research purity O2 inside the furnace tube via a PID-based pressure controller in concert with an inlet mass flow controller, and installing an automated liquid N2 distribution system, all driven by LabView® software. A separate system for cryogenic CO2 purification, dilution, and splitting is also fully automated, ensuring a highly repeatable process regardless of the operator. We present results from procedural blanks and an intercomparison material (CRONUS-A), as well as results of experiments to increase the amount of material used in extraction, from the standard 5 g to 10 g or above. Results thus far are quite promising with procedural blanks comparable to previous work and significant improvements in reproducibility for CRONUS-A measurements. The latter analyses also demonstrate the feasibility of quantitative extraction of in situ <span class="hlt">14</span><span class="hlt">C</span> from sample masses up to 10 g. Our lab is now analyzing unknowns routinely, but lowering overall blank levels is the focus of ongoing research.</p> </li> <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>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.osti.gov/scitech/biblio/6257823','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6257823"><span>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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000NIMPB.172..672P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000NIMPB.172..672P"><span>AMS measurements of <span class="hlt">14</span><span class="hlt">C</span> and 129I in seawater around radioactive waste dump sites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Povinec, P. P.; Oregioni, B.; Jull, A. J. T.; Kieser, W. E.; Zhao, X.-L.</p> <p>2000-10-01</p> <p>According to a recent IAEA compilation of inventories of radioactive wastes dumped in the world ocean, a total of 85 PBq of radioactive wastes were dumped, in the Atlantic (45 PBq), the Pacific (1.4 PBq) and the Arctic (38 PBq) Oceans and their marginal seas between 1946 and 1993, mostly in the form of low-level wastes. 3H, and <span class="hlt">14</span><span class="hlt">C</span> formed an important part of the beta-activity of these dumped wastes. Because of its long half-life, <span class="hlt">14</span><span class="hlt">C</span> will be the main constituent in possible leakages from the wastes in the future. On the other hand, <span class="hlt">14</span><span class="hlt">C</span> and 129I are important radioactive tracers which have been artificially introduced into the oceans. Small amounts of <span class="hlt">14</span><span class="hlt">C</span> and 129I can be easily measured by accelerator mass spectrometry (AMS) on mg-size samples of carbon and iodine extracted from 500 ml seawater samples. The high analytical sensitivity enables one therefore to find even trace amounts of <span class="hlt">14</span><span class="hlt">C</span> and 129I which could be released from radioactive wastes, and to compare the measured levels with the global distribution of these radionuclides. The IAEAs Marine Environment Laboratory (IAEA-MEL) has been engaged in an assessment program related to radioactive waste dumping in the oceans since 1992 and has participated in several expeditions to the Atlantic, Arctic, Indian and Pacific Oceans to sample seawater, biota and sediment for radiological assessment studies. In the present paper, we report on methods of <span class="hlt">14</span><span class="hlt">C</span> and 129I measurements in seawater by AMS and present data on the NE Atlantic, the Arctic and the NW Pacific Ocean dumping sites. A small increase of <span class="hlt">14</span><span class="hlt">C</span> was observed at the NE Atlantic dumping site.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFMPP43C..06M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFMPP43C..06M"><span>Intermediate water <span class="hlt">14</span><span class="hlt">C</span> evidence for the mechanism of deglacial CO2 increase</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marchitto, T. M.; Lehman, S. J.; Ortiz, J. D.; van Geen, A.</p> <p>2006-12-01</p> <p>Carbon sequestration in the ocean is widely considered to be the proximate cause of glacial CO2 lowering. The <span class="hlt">14</span><span class="hlt">C</span> activity of the atmosphere during the last glacial period appears to have been too high to be explained by increased cosmogenic production alone, implying that exchange of CO2 with the deep ocean must have been reduced. In other words, there must have been a relatively isolated deep ocean carbon reservoir. Likewise there was a sharp drop in atmospheric <span class="hlt">14</span><span class="hlt">C</span> activity coincident with the Termination I atmospheric CO2 increase, suggesting that the deep isolated reservoir, and therefore the carbon released from the ocean, was extremely depleted in <span class="hlt">14</span><span class="hlt">C</span>. Both the CO2 and <span class="hlt">14</span><span class="hlt">C</span> changes occurred in step with Antarctic warming, implicating the Southern Ocean as the main locus of carbon release. We therefore hypothesize that <span class="hlt">14</span><span class="hlt">C</span>-depleted waters should have spread to the intermediate/upper ocean via Antarctic Intermediate Water and Subantarctic Mode Water during the last deglaciation. We show that at ~700 m water depth off of southern Baja California, very <span class="hlt">14</span><span class="hlt">C</span>-depleted waters appeared in two stages during the last deglaciation, closely coincident with the atmospheric CO2 rise. The spectral reflectance record from our sediment core bears a remarkable resemblance to Greenland ice δ 18O, allowing us to assign calendar ages to our samples. Radiocarbon activity of paleo-waters is then calculated by age-correcting our benthic foraminiferal <span class="hlt">14</span><span class="hlt">C</span> measurements. During most of the 40,000 year record, intermediate water activity was ~100-200‰ lower than the atmosphere (like today), but during deglaciation this depletion increased to as much as 450‰. We suggest that this transient drop reflects the mixing of `old' carbon to the Southern Ocean surface, with spreading to the North Pacific via Antarctic Intermediate Water.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.2038K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.2038K"><span>Black carbon decomposition during 7 years and its transformation in soil estimated by <span class="hlt">14</span><span class="hlt">C</span> labeling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kuzyakov, Y.; Bogomolova, I.; Glaser, B.</p> <p>2012-04-01</p> <p>Incomplete combustion of organics (vegetation or fossil fuel) led to accumulation of charred products in soils. Such charred products, frequently called black carbon (BC), may act as an important long-term carbon (C) sink because its microbial decomposition and chemical transformation is very slow. There are no studies with direct estimations of BC decomposition rates and its transformation in soil. We produced BC by charring <span class="hlt">14</span><span class="hlt">C</span> labeled residues of perennial ryegrass and incubated this <span class="hlt">14</span><span class="hlt">C</span> labeled BC in a Haplic Luvisol or in loess. The decomposition rates of BC were estimated based on 14CO2 sampled 55 times during the 7-years incubation period. The decomposition rates of BC calculated based on <span class="hlt">14</span><span class="hlt">C</span> in CO2 were similar in soil and in loess and were about 10-5 d-1 (=10-3 % d-1). This corresponds to a decomposition of about 0.3% BC a-1 under optimal conditions. Considering about 10 times slower decomposition of BC under natural conditions, the mean residence time of BC is about 2000 years. Three years after the incubation start, we traced the BC transformation in soil by <span class="hlt">14</span><span class="hlt">C</span> incorporation into microbial biomass, DOC, PLFA, sugars, neutral lipids, glycolipids, sugars and benzene polycarboxylic acids. The most <span class="hlt">14</span><span class="hlt">C</span> (>80%) remained in benzene polycarboxylic acids confirming very high stability of BC. Incorporation of BC-<span class="hlt">14</span><span class="hlt">C</span> into microbial biomass, DOC and PLFA was less than 0.5%. We conclude that despite very high stability of BC and very slow process rates, the application of <span class="hlt">14</span><span class="hlt">C</span> labeling opens new ways for very sensitive tracing of BC transformation products in released CO2, microbial biomass, DOC, and SOM pools with various properties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.2126K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.2126K"><span>Decomposition and transformation of <span class="hlt">14</span><span class="hlt">C</span> labeled black carbon in soil</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kuzyakov, K.; Bogomolova, I.; Glaser, B.</p> <p>2012-04-01</p> <p>Incomplete combustion of organics (vegetation or fossil fuel) led to accumulation of charred products in soils. Such charred products, frequently called black carbon (BC), may act as an important long-term carbon (C) sink because its microbial decomposition and chemical transformation is very slow. There are no studies with direct estimations of BC decomposition rates and its transformation in soil. We produced BC by charring <span class="hlt">14</span><span class="hlt">C</span> labeled residues of perennial ryegrass and incubated this <span class="hlt">14</span><span class="hlt">C</span> labeled BC in a Haplic Luvisol or in loess. The decomposition rates of BC were estimated based on 14CO2 sampled 55 times during the 7-years incubation period. The decomposition rates of BC calculated based on <span class="hlt">14</span><span class="hlt">C</span> in CO2 were similar in soil and in loess and were about 10-5 d-1 (=10-3 % d-1). This corresponds to a decomposition of about 0.3% BC a-1 under optimal conditions. Considering about 10 times slower decomposition of BC under natural conditions, the mean residence time of BC is about 2000 years. Three years after the incubation start, we traced the BC transformation in soil by <span class="hlt">14</span><span class="hlt">C</span> incorporation into microbial biomass, DOC, PLFA, sugars, neutral lipids, glycolipids, sugars and benzene polycarboxylic acids. The most <span class="hlt">14</span><span class="hlt">C</span> (>80%) remained in benzene polycarboxylic acids confirming very high stability of BC. Incorporation of BC-<span class="hlt">14</span><span class="hlt">C</span> into microbial biomass, DOC and PLFA was less than 0.5%. We conclude that despite very high stability of BC and very slow process rates, the application of <span class="hlt">14</span><span class="hlt">C</span> labeling opens new ways for very sensitive tracing of BC transformation products in released CO2, microbial biomass, DOC, and SOM pools with various properties.</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>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>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://hdl.handle.net/2060/19850026782','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850026782"><span>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://www.ars.usda.gov/research/publications/publication/?seqNo115=235896','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=235896"><span>A Minute Dose of <span class="hlt">14</span><span class="hlt">C</span>-b-Carotene is Absorbed and Converted to Retinoids in Humans</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>We dosed 8 adults with <span class="hlt">14</span><span class="hlt">C</span>-all-trans [10,10',11,11'-<span class="hlt">14</span><span class="hlt">C</span>]-B-carotene (1.01 nmol) to quantify its absorption and metabolism. We used accelerator mass spectrometry (AMS) to measure <span class="hlt">14</span><span class="hlt">C</span> eliminated in feces over 14 days, in urine over 30 days, and that was retained in plasma over 166 days since dose. We...</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>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/19157836','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19157836"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/11432763','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11432763"><span>In vivo measurement of lipogenesis in ruminants using [1-(<span class="hlt">14</span>)<span class="hlt">C</span>]acetate.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Greathead, H M; Dawson, J M; Scollan, N D; Buttery, P J</p> <p>2001-07-01</p> <p>A method for the measurement of the rate of lipogenesis in ruminants using a continuous intravenous infusion of [1-(<span class="hlt">14</span>)<span class="hlt">C</span>]acetate and measuring the rate of [1-(<span class="hlt">14</span>)<span class="hlt">C</span>]acetate incorporation into adipose tissue lipid was evaluated. Subcutaneous adipose tissue samples obtained by biopsy over the course of a 6 h continuous intravenous infusion of [1-(<span class="hlt">14</span>)<span class="hlt">C</span>]acetate into a wether and a steer maintained in a 'metabolic steady state' demonstrated that the incorporation of [1-(<span class="hlt">14</span>)<span class="hlt">C</span>]acetate into subcutaneous adipose tissue lipid was linear for the duration of the infusion period. Subsequent measures of rates of [1-(<span class="hlt">14</span>)<span class="hlt">C</span>]acetate incorporation into adipose tissue lipid were made on adipose tissue samples taken at a single time point during the infusion period. The technique was used to measure rates of lipogenesis in the subcutaneous adipose tissue of fourteen Hereford x Friesian steers that had been fed a pelleted diet of dried grass at a range of metabolizable energy (ME) intakes from 1.1 x ME requirement for maintenance to ad libitum for 11 weeks. Rates of lipogenesis increased linearly with increasing ME intake. It was concluded that the method is an effective technique for measuring rates of lipogenesis in specific adipose tissue depots in vivo in ruminants.</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>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://adsabs.harvard.edu/abs/2012EGUGA..14.9514J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.9514J"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/26369226','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26369226"><span>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://adsabs.harvard.edu/abs/2016Ge%26Ae..56..858K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Ge%26Ae..56..858K"><span>Reconstructions of the <span class="hlt">14</span><span class="hlt">C</span> cosmogenic isotope content from natural archives after the last glacial termination</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kudryavtsev, I. V.; Volobuev, D. M.; Dergachev, V. A.; Nagovitsyn, Yu. A.; Ogurtsov, M. G.</p> <p>2016-12-01</p> <p>Data on the content of the <span class="hlt">14</span><span class="hlt">C</span> cosmogenic isotope in tree rings, which were obtained as a result of laboratory measurements, are often used when solar activity (SA) is reconstructed for previous epochs, in which direct observations are absent. However, these data contain information not only about SA variations but also about changes in the Earth climatic parameters, such as the global temperature and the CO2 content in the Earth's atmosphere. The effect of these variations on the <span class="hlt">14</span><span class="hlt">C</span> isotope content in different natural reservoirs after the last glacial termination to the middle of the Holocene is considered. The global temperature and the CO2 content increased on this time interval. In this case the <span class="hlt">14</span><span class="hlt">C</span> absolute content in the atmosphere increased on this time interval, even though the <span class="hlt">14</span><span class="hlt">C</span> to 12C isotope concentration ratio (as described by the Δ<span class="hlt">14</span><span class="hlt">C</span> parameter) decreased. These variations in the radiocarbon absolute content can be caused by its redistribution between natural reservoirs. It has been indicated that such a redistribution is possible only when the rate of carbon exchange between the ocean and atmosphere depends on temperature. The values of the corresponding temperature coefficient for the 17-10 ka BC time interval, which make it possible to describe the carbon redistribution between the ocean and atmosphere, have been obtained.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6240169','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6240169"><span>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('https://www.osti.gov/scitech/biblio/21192036','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21192036"><span>Measurement of {alpha} and neutron decay widths of excited states of {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>Haigh, P. J.; Ashwood, N. I.; Bloxham, T.; Curtis, N.; Freer, M.; McEwan, P.; Price, D.; Ziman, V.; Bohlen, H. G.; Kokalova, Tz.; Schulz, Ch.; Torabi, R.; Oertzen, W. von; Wheldon, C.; Catford, W.; Harlin, C.; Kalpakchieva, R.; Massey, T. N.</p> <p>2008-07-15</p> <p>The {sup 12}C({sup 16}O,{sup 14}O){sup <span class="hlt">14</span>}<span class="hlt">C</span> reaction was studied at a beam energy of 234 MeV. The {sup 14}O ejectile was detected by a Q3D spectrometer at forward angles. The energies and angles of the excited {sup <span class="hlt">14</span>}<span class="hlt">C</span> recoil break-up fragments were measured in coincidence with the {sup 14}O ejectile using a double sided silicon strip detector array at backward angles. A complete kinematic reconstruction of the reaction was performed to reconstruct the {sup <span class="hlt">14</span>}<span class="hlt">C</span>*{yields}{sup 10}Be+{alpha} and {sup <span class="hlt">14</span>}<span class="hlt">C</span>*{yields}{sup 13}C+n decay channels and the branching ratios and widths of these decays were calculated. Theoretical decay branches were calculated using barrier penetrability factors and were compared to the measured ratios to provide information on the spins, parities, and configurations of the states. Neutron emission was found to be favored for the 11.73, 12.96, 14.87, 16.72, and 18.6 MeV states. The 14.87, 18.6, and 21.4 MeV states were found to have a considerable width for {alpha}-decay and are candidates for the three bodied molecular cluster structure of {sup <span class="hlt">14</span>}<span class="hlt">C</span>.</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('https://www.osti.gov/scitech/biblio/6610884','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6610884"><span>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('http://adsabs.harvard.edu/abs/1999QuRes..52..159H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999QuRes..52..159H"><span>A 10,300 <span class="hlt">14</span><span class="hlt">C</span> yr Record of Climate and Vegetation Change from Haiti</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Higuera-Gundy, Antonia; Brenner, Mark; Hodell, David A.; Curtis, Jason H.; Leyden, Barbara W.; Binford, Michael W.</p> <p>1999-09-01</p> <p>Pleistocene and Holocene vegetation dynamics in the American tropics are inferred largely from pollen in continental lake sediments. Maritime influences may have moderated climate and vegetation changes on Caribbean islands. Stable isotope (δ18O) study of a 7.6-m core from Lake Miragoane, Haiti, provided a high-resolution record of changing evaporation/precipitation (E/P) since ∼10,300 <span class="hlt">14</span><span class="hlt">C</span> yr B.P. The Miragoane pollen record documents climate influences and human impacts on vegetation in Hispaniola. The δ18O and pollen data near the base of the core indicate cool, dry conditions before ∼10,000 <span class="hlt">14</span><span class="hlt">C</span> yr B.P. Lake Miragoane filled with water in the early Holocene as E/P declined and the freshwater aquifer rose. Despite increasing early Holocene moisture, shrubby, xeric vegetation persisted. Forest expanded ∼7000 <span class="hlt">14</span><span class="hlt">C</span> yr B.P. in response to greater effective moisture and warming. The middle Holocene (∼7000-3200 <span class="hlt">14</span><span class="hlt">C</span> yr B.P.) was characterized by high lake levels and greatest relative abundance of pollen from moist forest taxa. Climatic drying that began ∼3200 <span class="hlt">14</span><span class="hlt">C</span> yr B.P. may have driven some mesophilic animal species to extinction. The pollen record of the last millennium reflects pre-Columbian (Taino) and European deforestation. Long-term, Holocene vegetation trends in southern Haiti are comparable to trends from continental, lowland circum-Caribbean sites, suggesting a common response to regional climate change.</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>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://adsabs.harvard.edu/abs/2010AGUFMPP33B1687S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMPP33B1687S"><span>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.osti.gov/scitech/biblio/5642819','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5642819"><span>Differences in ( sup <span class="hlt">14</span> <span class="hlt">C</span>)glycerol utilization in normal and familial hypercholesterolemic fibroblasts</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Shireman, R.B.; Durieux, J. )</p> <p>1991-01-01</p> <p>It is known that cultured fibroblasts from familial hypercholesterolemia (FH) patients lack the normal cell receptor for low density lipoprotein (LDL) and that the absence of receptor-mediated transport of LDL cholesterol into these cells results in increased cellular synthesis of cholesterol. After 20 h perincubation in lipid-free medium, cultured FH fibroblasts incorporated significantly greater amounts of ({sup <span class="hlt">14</span>}<span class="hlt">C</span>)glycerol into cellular lipids than did normal fibroblasts. Relative to the control medium which contained only bovine serum albumin (BSA), preincubation with 5% fetal bovine serum or 50 micrograms LDL/ml decreased ({sup <span class="hlt">14</span>}<span class="hlt">C</span>)glycerol incorporation by both cell types. FH cells utilized more ({sup <span class="hlt">14</span>}<span class="hlt">C</span>)glycerol for phospholipid synthesis and less for triglyceride synthesis than normal cells. This study indicates that LDL may be important in the transport of glycerides, as well as cholesterol, to cells.</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>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('https://www.ncbi.nlm.nih.gov/pubmed/1217941','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/1217941"><span>[Fermentative degradation of 2-<span class="hlt">14</span><span class="hlt">C</span>-mannose with Leuconostoc mesenteroides (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>Ziegler, E; Dahmen, J</p> <p>1975-12-31</p> <p>Mannose-2-<span class="hlt">14</span><span class="hlt">C</span> has been fermented by Leuconostoc mesenteroides, CO2 ethanol and D-lactic acid were formed in a molar ratio of 1:1:1. A small amount of acetic acid was found as by-product. It could easily be isolated from the main products of the fermentation and it did not disturb further degradation procedures. The methyl-C-atom of ethanol, which was derived from C-2 of the mannose, had nearly the same specific radioactivity as mannose-2-<span class="hlt">14</span><span class="hlt">C</span>. All other C-atoms of the degradation products were only very slightly labeled. Their content of radioactivity was in any case lower than 3% of the specific radioactivity of the degraded mannose. This procedure is applicable for the degradation of <span class="hlt">14</span><span class="hlt">C</span>-labeled mannose.</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>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>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('https://www.ncbi.nlm.nih.gov/pubmed/16354793','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16354793"><span>UTP<span class="hlt">14</span><span class="hlt">c</span> is a recently acquired retrogene associated with spermatogenesis and fertility in man.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rohozinski, Jan; Lamb, Dolores J; Bishop, Colin E</p> <p>2006-04-01</p> <p>In the mouse, Utp14b is a retrogene transposed to an intron of Acsl3 (long-chain-fatty-acid coenzyme A ligase 3) on mouse chromosome 1. It represents a copy of Utp14a, a ubiquitously expressed, X-linked gene involved in 18S rRNA synthesis. The Utp14b is specifically expressed in male germ cells and, when mutated in the jsd (juvenile spermatogonial depletion) mouse, results in early spermatogenic arrest and male infertility. To understand the function and relevance of the orthologous human gene in testis pathology, we mapped transcripts and searched for mutations within the gene in infertile males. In humans, the strict ortholog of UTP14b has degenerated and is no longer functional. However, a second active retroposon, UTP<span class="hlt">14</span><span class="hlt">c</span>, is found within a widely expressed, putative glycosyl transferase-containing gene, GT8, on human chromosome 13. Unlike mouse Utp14b, which is only expressed in the male germ line, human UTP<span class="hlt">14</span><span class="hlt">c</span> is expressed in testis and ovary, which is consistent with having a gonad-specific function. To determine if UTP<span class="hlt">14</span><span class="hlt">c</span> is functionally equivalent to mouse Utp14b and essential to spermatogenesis in humans, we screened DNA from 234 nonobstructive, azoospermic/severely oligospermic males and 208 proven-fertile controls for mutations within UTP<span class="hlt">14</span><span class="hlt">c</span>. We identified a mutation in three unrelated patients that introduces an in-frame stop codon truncating the UTP<span class="hlt">14</span><span class="hlt">c</span> protein near the carboxyl terminus. These data indicate that UTP<span class="hlt">14</span><span class="hlt">c</span> may be functionally equivalent to mouse Utp14b and required for normal male fertility in humans. The novel evolution of retroposed UTP14 genes supports the hypothesis that retrogenes play an important role in evolution via regulation of male reproductive fitness.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25217486','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25217486"><span>Disposition and metabolic profiling of [(<span class="hlt">14</span>)<span class="hlt">C</span>]cerlapirdine using accelerator mass spectrometry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tse, Susanna; Leung, Louis; Raje, Sangeeta; Seymour, Mark; Shishikura, Yoko; Obach, R Scott</p> <p>2014-12-01</p> <p>Cerlapirdine (SAM-531, PF-05212365) is a selective, potent, full antagonist of the 5-hydroxytryptamine 6 (5-HT6) receptor. Cerlapirdine and other 5-HT6 receptor antagonists have been in clinical development for the symptomatic treatment of Alzheimer's disease. A human absorption, distribution, metabolism, and excretion study was conducted to gain further understanding of the metabolism and disposition of cerlapirdine. Because of the low amount of radioactivity administered, total (<span class="hlt">14</span>)<span class="hlt">C</span> content and metabolic profiles in plasma, urine, and feces were determined using accelerator mass spectrometry (AMS). After a single, oral 5-mg dose of [(<span class="hlt">14</span>)<span class="hlt">C</span>]cerlapirdine (177 nCi), recovery of total (<span class="hlt">14</span>)<span class="hlt">C</span> was almost complete, with feces being the major route of elimination of the administered dose, whereas urinary excretion played a lesser role. The extent of absorption was estimated to be at least 70%. Metabolite profiling in pooled plasma samples showed that unchanged cerlapirdine was the major drug-related component in circulation, representing 51% of total (<span class="hlt">14</span>)<span class="hlt">C</span> exposure in plasma. One metabolite (M1, desmethylcerlapirdine) was detected in plasma, and represented 9% of the total (<span class="hlt">14</span>)<span class="hlt">C</span> exposure. In vitro cytochrome P450 reaction phenotyping studies showed that M1 was formed primarily by CYP2C8 and CYP3A4. In pooled urine samples, three major drug-related peaks were detected, corresponding to cerlapirdine-N-oxide (M3), cerlapirdine, and desmethylcerlapirdine. In feces, cerlapirdine was the major (<span class="hlt">14</span>)<span class="hlt">C</span> component excreted, followed by desmethylcerlapirdine. The results of this study demonstrate that the use of the AMS technique enables comprehensive quantitative elucidation of the disposition and metabolic profiles of compounds administered at a low radioactive dose.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6617806','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6617806"><span>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>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/2648055','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/2648055"><span>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('http://adsabs.harvard.edu/abs/2016EGUGA..1817289P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1817289P"><span>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('https://www.osti.gov/scitech/biblio/5502689','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5502689"><span>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> <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>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('http://adsabs.harvard.edu/abs/2000NIMPB.172...95L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000NIMPB.172...95L"><span>AMS at ANTARES - The first 10 years</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lawson, E. M.; Elliott, G.; Fallon, J.; Fink, D.; Hotchkis, M. A. C.; Hua, Q.; Jacobsen, G. E.; Lee, P.; Smith, A. M.; Tuniz, C.; Zoppi, U.</p> <p>2000-10-01</p> <p>The status and capabilities of the ANTARES AMS facility after 10 years are reviewed. The common AMS radioisotopes, 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, are routinely analysed. A capability for the detection of 236U and other actinide isotopes has been developed. The measurement program includes support to Quaternary science projects at Australian universities and to ANSTO projects in global climate change and nuclear safeguards.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9635058','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9635058"><span>Effects of taurine and light on retinal GABA content and the efflux of <span class="hlt">14</span><span class="hlt">C</span>-GABA and <span class="hlt">14</span><span class="hlt">C</span>-aspartate from frog retina.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Haroutounian, J E; Petrosian, A M</p> <p>1998-01-01</p> <p>GABA content of isolated, dark adapted frog retina was found to be 3.15 +/- 0.28 mM. After 30 minutes of exposure to intense light (200 lx), retinal GABA levels increased about 70%. Interestingly, incubation of dark adapted retina for 30 minutes with medium containing 0.4 mM taurine also led to a 70% increase in GABA levels. Since the light-induced elevation in GABA content was reduced over 50% by a simultaneous injection of 0.02 mM strychinine, it is likely that the light-induced GABA change is partly mediated by the release of taurine from the retina seen after light exposure. However, incubation of isolated retina with medium containing increasing concentrations of taurine (1, 2 and 20 mM), caused a progressive rise in <span class="hlt">14</span><span class="hlt">C</span>-GABA efflux from retina that was preloaded with 2.2 microM GABA and exposed to dim light (0.05 lx). It was also shown that taurine (1 and 5 mM) dramatically reduced <span class="hlt">14</span><span class="hlt">C</span>-aspartate efflux from retina preloaded with radioactive aspartate and exposed to dim light conditions. By comparison, intense light stimulation (40 lx) reduced basal <span class="hlt">14</span><span class="hlt">C</span>-aspartate efflux while dark exposure increased <span class="hlt">14</span><span class="hlt">C</span>-aspartate loss from the isolated retina. We found that taurine depressed the b-wave signal of frog retina, with the maximum effect occurring at a concentration of 1 mM. Addition of strychnine (0.4 mM) reversed the taurine effect on the b-wave, indicating that taurine receptors must be present in the inner retina. By contrast, taurine (0.1-20 mM) had no effect on the P111 component of the ERG initiated by either aspartate or cobalt. However, taurine exerted a modest depressant activity on P111 initiated by glutamate. The significance of these data relative to the putative neurotransmitter function of taurine in the inner retina is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JSSCh.204..233D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JSSCh.204..233D"><span>Phase polymorphism of novel [Ru(NH3)6](ClO4)3—Comparison with [Ru(NH3)6](BF4)3. Part II</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dołęga, Diana; Mikuli, Edward; Górska, Natalia; Inaba, Akira; Hołderna-Natkaniec, Krystyna; Nitek, Wojciech</p> <p>2013-08-01</p> <p>[Ru(NH3)6](ClO4)3 undergoes two phase transitions at: TC1=290.3 K and TC2=74.8 K , thus exhibits three crystalline phases in the temperature range of 5-310 K. For the detected phase transitions, thermal effects were determined. Fourier transform far- and middle-infrared spectra (FT-FIR and FT-MIR), recorded at 8-350 K, suggest that reorientational motions of the NH3 ligands are very fast (τR≈10-12 s above TC1) and are significantly slowed down below TC2. X-ray single crystal diffraction (XRSCD) measurements revealed that in the high temperature phase (above TC1) the compound belongs to the cubic Fm3barm (No. 225) space group, whereas in the intermediate phase the unit cell parameter doubles and the space group is Ia3bar(No. 206). 1H NMR studies revealed that the following reorientational motions are liberated during heating: three-fold reorientation of NH3 ligands, three-fold reorientation of the entire [Ru(NH3)6]3+ cation, and isotropic reorientation of this cation. In the high temperature phase I the cations perform isotropic reorientations with the estimated activation energy equal to ca. 30.1 kJ mol-1. Comparison with adequate results obtained earlier for [Ru(NH3)6](BF4)3 and for other similar compounds was made and general regularities were drawn.</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/2017E%26PSL.457..271R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017E%26PSL.457..271R"><span>Inner gorges incision history: A proxy for deglaciation? Insights from Cosmic Ray Exposure dating (10Be and <span class="hlt">36</span><span class="hlt">Cl</span>) of river-polished surfaces (Tinée River, SW Alps, France)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rolland, Y.; Petit, C.; Saillard, M.; Braucher, R.; Bourlès, D.; Darnault, R.; Cassol, D.</p> <p>2017-01-01</p> <p>10Be and <span class="hlt">36</span><span class="hlt">Cl</span> Cosmic Ray Exposure (CRE) dating performed on river polished surfaces of river gorges in a mountain-to-sea river system in the French SW Alps highlights transient erosional events involving incision rates >10 mm a-1. These events took place during the last two major deglaciation phases following (1) the Last Glacial Maximum (LGM) at 16-14 ka, (2) the Younger Dryas at 8-11 ka, and during the warm and humid Holocene climatic optimum at 4-5 ka. These periods of high incision rates (3- > 30 mma-1) alternated with periods of low incision rates (<1 mm a-1), which probably correspond to a long-term equilibrium between incision and relative uplift. The Alpine river staircase shape profiles evidence local and transient responses that are ascribed to cumulate disequilibrium after the long-time-spanned glaciations. After each glaciation, rivers rush down to get closer to their equilibrium profile. Incision is amplified both by the sediment discharge due to the erosion of moraines and by landslides triggered by the glacier retreat.</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>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('https://www.ncbi.nlm.nih.gov/pubmed/26661153','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26661153"><span>Kinetic study of benzyl [1-<span class="hlt">14</span><span class="hlt">C</span>]acetate as a potential probe for astrocytic energy metabolism in the rat brain: Comparison with benzyl [2-<span class="hlt">14</span><span class="hlt">C</span>]acetate.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Okada, Maki; Yanamoto, Kazuhiko; Kagawa, Tomohiko; Yoshino, Keiko; Hosoi, Rie; Abe, Kohji; Zhang, Ming-Rong; Inoue, Osamu</p> <p>2016-02-01</p> <p>Brain uptake of [(<span class="hlt">14</span>)<span class="hlt">C</span>]acetate has been reported to be a useful marker of astrocytic energy metabolism. In addition to uptake values, the rate of radiolabeled acetate washout from the brain appears to reflect CO2 exhaustion and oxygen consumption in astrocytes. We measured the time-radioactivity curves of benzyl [1-(<span class="hlt">14</span>)<span class="hlt">C</span>]acetate ([1-(<span class="hlt">14</span>)<span class="hlt">C</span>]BA), a lipophilic probe of [1-(<span class="hlt">14</span>)<span class="hlt">C</span>]acetate, and compared it with that of benzyl [2-(<span class="hlt">14</span>)<span class="hlt">C</span>]acetate ([2-(<span class="hlt">14</span>)<span class="hlt">C</span>]BA) in rat brains. The highest brain uptake was observed immediately after injecting either [1-(<span class="hlt">14</span>)<span class="hlt">C</span>]BA or [2-(<span class="hlt">14</span>)<span class="hlt">C</span>]BA, and both subsequently disappeared from the brain in a single-exponential manner. Estimated [1-(<span class="hlt">14</span>)<span class="hlt">C</span>]BA washout rates in the cerebral cortex and cerebellum were higher than those of [2-(<span class="hlt">14</span>)<span class="hlt">C</span>]BA. These results suggested that [1-(<span class="hlt">14</span>)<span class="hlt">C</span>]BA could be a useful probe for estimating the astrocytic oxidative metabolism. The [1-(<span class="hlt">14</span>)<span class="hlt">C</span>]BA washout rate in the cerebral cortex of immature rats was lower than that of mature rats. An autoradiographic study showed that the washout rates of [1-(<span class="hlt">14</span>)<span class="hlt">C</span>]BA from the rat brains of a lithium-pilocarpine-induced status epilepticus model were not significantly different from the values in control rat brains except for the medial septal nucleus. These results implied that the enhancement of amino acid turnover rate rather than astrocytic oxidative metabolism was increased in status epilepticus.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5233266','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5233266"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/9674960','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9674960"><span>In vivo percutaneous absorption of [<span class="hlt">14</span><span class="hlt">C</span>]DEHP from [<span class="hlt">14</span><span class="hlt">C</span>]DEHP-plasticized polyvinyl chloride film in male Fischer 344 rats.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Deisinger, P J; Perry, L G; Guest, D</p> <p>1998-06-01</p> <p>These studies investigated the migration of di(2-ethylhexyl) phthalate (DEHP) contained as a plasticizer in polyvinyl chloride (PVC) from plastic film and its absorption through rat skin in iivo. Sheets of PVC film (15 cm2) plasticized with [<span class="hlt">14</span><span class="hlt">C</span>]DEHP were applied to the shaved backs of eight male rats in two separate experiments. For Study I, the PVC film was removed after 24 hr, the animals were rewrapped to prevent them from ingesting any residual DEHP at the exposure site, and urine and faeces were collected at regular intervals for 7 days. For Study II, the PVC film was removed after 24 hr, and the animals were immediately killed by CO2 inhalation. Urine and faeces were collected at 24 hr, and the exposure site was washed and rinsed to remove residual [<span class="hlt">14</span><span class="hlt">C</span>]DEHP. In both studies, the amounts of radioactivity transferred from the film were extremely small, amounting to 0.0643% (Study I) and 0.126% (Study II) of that applied. The transferred radioactivity was found to be in three separate fractions. Radioactivity readily removed from the skin (mean 75% of the transferred radioactivity), radioactivity remaining at the application site at sacrifice. and absorbed radioactivity, that is, that distributed systemically or eliminated. The mean absorption rates for DEHP, calculated from the sum of the quantities absorbed plus that present in the exposure site, were: Study I, 0.239, and Study II, 0.242 microg/cm2/hr.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/7163073','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/7163073"><span>Behavior of [[sup <span class="hlt">14</span>]<span class="hlt">C</span>]-4-nitrophenol and [[sup <span class="hlt">14</span>]<span class="hlt">C</span>]-3,4-dichloroaniline in lab sediment-water systems; 1: Metabolic fate and partitioning of radioactivity</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Heim, K.; Schuphan, I.; Schmidt, B. . Rheinisch-Westfaelische Technische Hochschule Aachen)</p> <p>1994-06-01</p> <p>Using a standard screening procedure, the fate of [[sup <span class="hlt">14</span>]<span class="hlt">C</span>]-4-nitrophenol and [[sup <span class="hlt">14</span>]<span class="hlt">C</span>]-3,4-dichloroaniline was studied in lab sediment-water systems; incubation intervals ranged from 4 h to 90 d. The sediments were collected from a creek, a pond, and a drainage ditch of a fruit-growing plantation, and were characterized. Both compounds and their transformation products were sorbed to the sediments in large quantities; radioactivity left in the water phase was below 11% after termination of the experiments. Besides minor amounts of [sup 14]CO[sub 2], 3,4-dichloroaniline was converted to predominantly nonextractable residues, presumably without preceding microbial transformation of the 3,4-dichloroaniline moiety. Two main end products were observed in the 4-nitrophenol experiments, namely nonextractable residues and [sup 14]CO[sub 2]. Data obtained from the sediment exhibiting highest microbial activity probably indicated a further mineralization of 4-nitrophenol-derived sediment-bound residues. On the whole, 4-nitrophenol presumably shows low persistence and accumulation in sediment-water systems, whereas due to its stability the toxicity of sediment-sorbed 3,4-dichloroaniline should be examined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27593710','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27593710"><span>Pharmacokinetics of (<span class="hlt">14</span>) <span class="hlt">C</span>-ortho-phenylphenol following intravenous administration in pigs.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nixon, Emma; Brooks, James D; Routh, Patricia A; Chittenden, Jason T; Baynes, Ronald E</p> <p>2017-04-01</p> <p>Workers in the USA are exposed to industrial formulations, which may be toxic. These formulations often contain preservatives or biocides such as ortho-phenylphenol (OPP). There are limited data describing OPP following intravenous administration to assess truly the clearance of this chemical in humans and other species. In vivo experiments were conducted in pigs to determine related pharmacokinetic parameters. (<span class="hlt">14</span>) <span class="hlt">C</span>-OPP was administered as an intravenous bolus dose. Blood, feces, urine and tissue samples were collected for analysis by liquid scintillation. Data were analyzed using non-compartmental and compartmental pharmacokinetic model approaches. These data fitted a three-compartment model and showed that the half-life of (<span class="hlt">14</span>) <span class="hlt">C</span>-OPP following the intravenous bolus in pigs was 46.26 ± 10.01 h. The kidneys play a crucial role in clearance of (<span class="hlt">14</span>) <span class="hlt">C</span>-OPP with a large percentage of the dose being found in the urine (70.3 ± 6.9% dose). Comparisons with other species suggest that (<span class="hlt">14</span>) <span class="hlt">C</span>-OPP clearance in pigs (2.48 ml h(-1)  kg(-1) ) is less than that in humans (18.87 ml h(-1)  kg(-1) ) and rats (35.51 ml h(-1)  kg(-1) ). Copyright © 2016 John Wiley & Sons, Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3768407','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3768407"><span>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/70017119','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70017119"><span>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://adsabs.harvard.edu/abs/2016ChPhC..40k1001T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ChPhC..40k1001T"><span>Cluster decay of the high-lying excited states in <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>Tian, Z. Y.; Ye, Y. L.; Li, Z. H.; Lin, C. J.; Li, Q. T.; Ge, Y. C.; Lou, J. L.; Jiang, W.; Li, J.; Yang, Z. H.; Feng, J.; Li, P. J.; Chen, J.; Liu, Q.; Zang, H. L.; Yang, B.; Zhang, Y.; Chen, Z. Q.; Liu, Y.; Sun, X. H.; Ma, J.; Jia, H. M.; Xu, X. X.; Yang, L.; Ma, N. R.; Sun, L. J.</p> <p>2016-11-01</p> <p>A cluster-transfer experiment of 9Be(9Be,<span class="hlt">14</span><span class="hlt">C</span> → α+10Be)α at an incident energy of 45 MeV was carried out in order to investigate the molecular structure in high-lying resonant states in <span class="hlt">14</span><span class="hlt">C</span>. This reaction is of extremely large Q-value, making it an excellent case to select the reaction mechanism and the final states in outgoing nuclei. The high-lying resonances in <span class="hlt">14</span><span class="hlt">C</span> are reconstructed for three sets of well discriminated final states in 10Be. The results confirm the previous decay measurements with clearly improved decay-channel selections and also show a new state at 23.5(1) MeV. The resonant states at 22.4(3) and 24.0(3) MeV decay primarily into the typical molecular states at about 6 MeV in 10Be, indicating a well developed cluster structure in these high-lying states in <span class="hlt">14</span><span class="hlt">C</span>. Further measurements of more states of this kind are suggested. Supported by the 973 Program of China (2013 CB834402) and National Natural Science Foundation of China (11275011, 11535004)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20015221','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20015221"><span>Ambiguous hydraulic heads and <span class="hlt">14</span><span class="hlt">C</span> activities in transient regional flow.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Schwartz, Franklin W; Sudicky, Edward A; McLaren, Robert G; Park, Young-Jin; Huber, Matthew; Apted, Mick</p> <p>2010-01-01</p> <p>A regional flow and transport model is used to explore the implications of significant variability in Pleistocene and Holocene climates on hydraulic heads and (<span class="hlt">14</span>)<span class="hlt">C</span> activity. Simulations involve a 39 km slice of the Death Valley Flow System through Yucca Mountain toward the Amargosa Desert. The long-time scale over which infiltration has changed (tens-of-thousands of years) is matched by the large physical extent of the flow system (many tens-of-kilometers). Estimated paleo-infiltration rates were estimated using a juniper pollen percentage that extends from the last interglacial (LIG) period (approximately 120 kyrbp) to present. Flow and (<span class="hlt">14</span>)<span class="hlt">C</span> transport simulations show that groundwater flow changes markedly as a function of paleoclimate. At the last glacial maximum (LGM, 21 kyrbp), the recharge to the flow system was about an order-of-magnitude higher than present, and water table was more than 100 m higher. With large basin time constants, flow is complicated because hydraulic heads at a given location reflect conditions of the past, but at another location the flow may reflect present conditions. This complexity is also manifested by processes that depend on flow, for example (<span class="hlt">14</span>)<span class="hlt">C</span> transport. Without a model that accounts for the historical transients in recharge for at least the last 20,000 years, there is no simple way to deconvolve the (<span class="hlt">14</span>)<span class="hlt">C</span> dates to explain patterns of flow.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25989260','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25989260"><span>Impact of activated carbon on the catabolism of (<span class="hlt">14</span>)<span class="hlt">C</span>-phenanthrene 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>Oyelami, Ayodeji O; Ogbonnaya, Uchenna; Muotoh, Chitom; Semple, Kirk T</p> <p>2015-06-01</p> <p>Activated carbon amendment to contaminated soil has been proposed as an alternative remediation strategy to the management of persistent organic pollutant in soils and sediments. The impact of varying concentrations (0%, 0.01%, 0.1% and 1.0%) of different types of AC on the development of phenanthrene catabolism in soil was investigated. Mineralisation of (<span class="hlt">14</span>)<span class="hlt">C</span>-phenanthrene was measured using respirometric assays. The increase in concentration of CB4, AQ5000 or CP1 in soil led to an increase in the length of the lag phases. Statistical analyses showed that the addition of increasing concentrations of AC to the soil significantly reduced (P < 0.05) the extent of (<span class="hlt">14</span>)<span class="hlt">C</span>-phenanthrene mineralisation. For example, for CB4-, AQ5000- and CP1-amended soils, the overall extent of (<span class="hlt">14</span>)<span class="hlt">C</span>-phenanthrene mineralisation reduced from 43.1% to 3.28%, 36.9% to 0.81% and 39.6% to 0.96%, respectively, after 120 days incubation. This study shows that the properties of AC, such as surface area, pore volume and particle size, are important factors in controlling the kinetics of (<span class="hlt">14</span>)<span class="hlt">C</span>-phenanthrene mineralisation in soil.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27602486','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27602486"><span>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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5512198','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5512198"><span>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('https://www.osti.gov/scitech/biblio/5731265','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5731265"><span>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://www.osti.gov/scitech/servlets/purl/757416','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/757416"><span><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('https://www.ncbi.nlm.nih.gov/pubmed/1140877','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/1140877"><span>[Analog computer analysis of radioactivity kinetics in man following oral administration of tilidine HCl-<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>Ringwelski, L</p> <p>1975-03-01</p> <p>Models for studying the absorption and elimination kinetics of <span class="hlt">14</span>-<span class="hlt">C</span> labelled DL-Ethyl-trans-2-dimethylamino-1-phenyl-cyclohex-3-ene-trans-1-carboxylate-hydrochloride (Tilidine - HCl, Valoron) are developed, based on the concentration vs. time of radioactivity in the plasma following a single oral administration in man. For this purpose, the average concentration values in the plasma of 3 healthy adults, as given by Vollmer and Poisson [12] were employed. 1. Two three-compartment-models were developed which simulate with sufficient accuracy the <span class="hlt">14</span>-<span class="hlt">C</span>-Valoron concentration curve in the plasma. 2. Computer analysis enables one to determine the distribution of <span class="hlt">14</span>-<span class="hlt">C</span>-Valoron among the intra- and extravasal compartments and the half life for absorption t1/2 equals 0.57 h, for transport from plasma into the extravasal compartment t1/2 equals 3.31 h, for resorption t1/2 equals 4.11 h, for elimination with feces t1/2 equals 29.5 h and for elimination in urine t1/2 equals 8.75 h. 3. The use of two different models allows one to draw conclusions concerning the participation of parenchymatous organs in storage and elimination. 4. The probable radioactivity curve is calculated for repeated oral application of <span class="hlt">14</span>-<span class="hlt">C</span>-Valoron in 8 hours intervals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JNuM..448..113L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JNuM..448..113L"><span>Characterization of <span class="hlt">14</span><span class="hlt">C</span> in neutron irradiated NBG-25 nuclear 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; Dunzik-Gougar, Mary Lou</p> <p>2014-05-01</p> <p>Recent studies suggest that the highest concentration of <span class="hlt">14</span><span class="hlt">C</span> contamination present in reactor-irradiated graphite exists on the surfaces and within near-surface layers. Surface-sensitive analysis techniques (XPS, ToF-SIMS, SEM/EDS and Raman) were employed to determine the chemical nature of <span class="hlt">14</span><span class="hlt">C</span> on irradiated NBG-25 (nuclear grade) graphite surfaces. Several <span class="hlt">14</span><span class="hlt">C</span> precursor species are identified on the surfaces of irradiated NBG-25; the quantities of these species decrease at sub-surface depths, which further suggests that <span class="hlt">14</span><span class="hlt">C</span> formation is predominantly a surface-concentrated phenomenon. The elevated presence of several surface oxide complexes on irradiated NBG-25 surfaces are attributed directly to neutron irradiation. Larger numbers of oxide bonds were found on irradiated NBG-25 surfaces (when compared to unirradiated samples) in the form of interlattice (e.g. ether) and dangling (e.g. carboxylate and ketone) bonds; the quantities of these bond types also decrease with increasing sub-surface depths.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5640341','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5640341"><span>A kinetic and microautoradiographic study of sup <span class="hlt">14</span> <span class="hlt">C</span>-sucrose translocation into developing wheat grains</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ning Wang; Fisher, D.B. )</p> <p>1991-05-01</p> <p>The kinetics of {sup <span class="hlt">14</span>}<span class="hlt">C</span>-photosynthate import by developing wheat grains was followed after pulse-labeling the flag leaf with {sup 14}CO{sub 2}. Samples were collected from four successive points along the transport pathway to and within the grain: exuding aphid stylets on the peduncle, exuding grain pedicels, the grain crease tissues, and the liquid contents of the endosperm cavity. In addition, microautoradiographs were prepared of the grain crease tissues during movement of the {sup <span class="hlt">14</span>}<span class="hlt">C</span> pulse into the grain. At all times, sucrose accounted for 93 to 97% of the total {sup <span class="hlt">14</span>}<span class="hlt">C</span> present at all four sampling sites. The main features of the {sup <span class="hlt">14</span>}<span class="hlt">C</span> kinetics could be accounted for by a simple compartmental model consisting of sucrose pools in series. Microautoradiographs of the crease tissues showed fairly uniform labeling of vascular parenchyma at all times, with a sharp gradient in labeling across the chalaza to the nucellus. Thus the principal resistance to post-phloem solute transport through the maternal tissues appears to be in the symplastic pathway across the chalaza.</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>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> </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('https://www.ncbi.nlm.nih.gov/pubmed/22717552','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22717552"><span>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.ncbi.nlm.nih.gov/pubmed/24805288','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24805288"><span>Pharmacokinetic analysis of <span class="hlt">14</span><span class="hlt">C</span>-ursodiol in newborn infants using accelerator mass spectrometry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gordi, Toufigh; Baillie, Rebecca; Vuong, Le T; Abidi, Saira; Dueker, Stephen; Vasquez, Herbert; Pegis, Priscilla; Hopper, Andrew O; Power, Gordon G; Blood, Arlin B</p> <p>2014-09-01</p> <p>Pharmacokinetic studies in the neonatal population are often limited by the small volume of blood that can be collected. The high sensitivity of (<span class="hlt">14</span>) <span class="hlt">C</span>-accelerator mass spectrometry (AMS) enables pharmacokinetic studies to be conducted with greatly reduced sample volumes. We demonstrated the utility of AMS in infants by studying the plasma pharmacokinetic behavior of nanogram doses of (<span class="hlt">14</span>) <span class="hlt">C</span>-ursodiol administered as a non-perturbing microdose or as a microtracer with therapeutic doses of non-labeled ursodiol in infants. Five non-cholestatic infants were administered 3 consecutive oral microdoses of (<span class="hlt">14</span>) <span class="hlt">C</span>-ursodiol: 8 ng (1.0 nCi), 26 ng (3.3 nCi), and 80 ng (10 nCi) 48 hours apart. Three additional infants with cholestasis were administered a single 80 ng (10.0 nCi) oral dose of (<span class="hlt">14</span>) <span class="hlt">C</span>-ursodiol together with a therapeutic dose of 40 mg/kg of non-labeled ursodiol. A pharmacokinetic model describing ursodiol concentrations was developed using nonlinear mixed-effects modeling. The pharmacokinetics of ursodiol in this pilot study were best described by a two-compartment model with first-order elimination. This study demonstrates the feasibility and utility of microdose and microtrace methodology in pediatric research.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://aem.asm.org/content/64/4/1560.abstract','USGSPUBS'); return false;" href="http://aem.asm.org/content/64/4/1560.abstract"><span>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, Paul M.; Landmeyer, James E.; Dinicola, Richard 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('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>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://adsabs.harvard.edu/abs/1991PhRvC..44.2884H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1991PhRvC..44.2884H"><span>Comment on ``Interpretation of the fine structure in the <span class="hlt">14</span><span class="hlt">C</span> radioactive decay of 223'</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hussonnois, M.; Le Du, J. F.; Brillard, L.; Ardisson, G.</p> <p>1991-12-01</p> <p>Priority of our interpretation of the fine structure in the <span class="hlt">14</span><span class="hlt">C</span> radioactive decay of 223Ra is asserted. It seems that the deformation parameter values, used in the framework of ARM to interpret properties of both 223Ra ground and excited states, partly allow for the qualitative interpretation of the experimental hindrance factors to the 209Pb states.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=106189','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=106189"><span>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://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bradley, Paul M.; Landmeyer, James E.; Dinicola, Richard S.</p> <p>1998-01-01</p> <p>Anaerobic oxidation of [1,2-<span class="hlt">14</span><span class="hlt">C</span>]dichloroethene to 14CO2 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. PMID:16349554</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GeCoA.105...14F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeCoA.105...14F"><span><span class="hlt">14</span><span class="hlt">C</span> and 13C characteristics of higher plant biomarkers in Washington margin surface sediments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Feng, Xiaojuan; Benitez-Nelson, Bryan C.; Montluçon, Daniel B.; Prahl, Fredrick G.; McNichol, Ann P.; Xu, Li; Repeta, Daniel J.; Eglinton, Timothy I.</p> <p>2013-03-01</p> <p>Plant wax lipids and lignin phenols are the two most common classes of molecular markers that are used to trace vascular plant-derived OM in the marine environment. However, their 13C and <span class="hlt">14</span><span class="hlt">C</span> compositions have not been directly compared, which can be used to constrain the flux and attenuation of terrestrial carbon in marine environment. In this study, we describe a revised method of isolating individual lignin phenols from complex sedimentary matrices for <span class="hlt">14</span><span class="hlt">C</span> analysis using high pressure liquid chromatography (HPLC) and compare this approach to a method utilizing preparative capillary gas chromatography (PCGC). We then examine in detail the 13C and <span class="hlt">14</span><span class="hlt">C</span> compositions of plant wax lipids and lignin phenols in sediments from the inner and mid shelf of the Washington margin that are influenced by discharge of the Columbia River. Plant wax lipids (including n-alkanes, n-alkanoic (fatty) acids, n-alkanols, and n-aldehydes) displayed significant variability in both δ13C (-28.3‰ to -37.5‰) and Δ<span class="hlt">14</span><span class="hlt">C</span> values (-204‰ to +2‰), suggesting varied inputs and/or continental storage and transport histories. In contrast, lignin phenols exhibited similar δ13C values (between -30‰ and -34‰) and a relatively narrow range of Δ<span class="hlt">14</span><span class="hlt">C</span> values (-45‰ to -150‰; HPLC-based measurement) that were similar to, or younger than, bulk OM (-195‰ to -137‰). Moreover, lignin phenol <span class="hlt">14</span><span class="hlt">C</span> age correlated with the degradation characteristics of this terrestrial biopolymer in that vanillyl phenols were on average ˜500 years older than syringyl and cinnamyl phenols that degrade faster in soils and sediments. The isotopic characteristics, abundance, and distribution of lignin phenols in sediments suggest that they serve as promising tracers of recently biosynthesized terrestrial OM during supply to, and dispersal within the marine environment. Lignin phenol <span class="hlt">14</span><span class="hlt">C</span> measurements may also provide useful constraints on the vascular plant end member in isotopic mixing models for carbon source</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008DSRII..55.2438P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008DSRII..55.2438P"><span><span class="hlt">14</span><span class="hlt">C</span> as a tracer of labile organic matter in Antarctic benthic food webs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Purinton, Brett L.; DeMaster, David J.; Thomas, Carrie J.; Smith, Craig R.</p> <p>2008-11-01</p> <p><span class="hlt">14</span><span class="hlt">C</span> measurements were made on surface plankton, particle-trap material, surface sediment, benthic invertebrate gut contents, and body tissue samples to assess the effectiveness of this radioisotope as a tracer of labile organic carbon in Antarctic benthic food webs. Samples were collected on five cruises to the West Antarctic Peninsula (WAP) shelf between November 1999 and March 2001 as part of the Food for Benthos on the ANtarctic Continental-Shelf (FOODBANCS) Project. The <span class="hlt">14</span><span class="hlt">C</span> contents of the body tissues from a variety of deposit feeders (-126±13 per mil) were substantially enriched relative to the surface sediment (-234±13 per mil) and statistically similar to the organic matter collected in plankton tows (-135±10 per mil), indicating that recently produced marine plankton are the primary source of nutrition for these deposit feeders on the West Antarctic shelf. Selective ingestion was the primary feeding strategy used by echiuran worms and certain holothurians (i.e. Peniagone vignoni) for incorporating labile organic carbon into their tissues as demonstrated by the large differences (105±13 per mil) between surface sediment and gut content <span class="hlt">14</span><span class="hlt">C</span> activities. In contrast, digestive and/or assimilatory selection was the predominant strategy used by an irregular urchin ( Amphipneustes lorioli) and several other holothurians ( Protelpidia murrayi, Bathyplotes fuscivinculum and the head-down conveyor belt feeder, Molpadia musculus), as demonstrated by large differences (42±7 per mil) between the <span class="hlt">14</span><span class="hlt">C</span> activities of their foregut or whole-gut organic contents and their body tissues. Despite large fluctuations in carbon export from the euphotic zone, benthic feeding strategies remained essentially constant over the 15-month sampling period. No seasonal variation was evident in either the <span class="hlt">14</span><span class="hlt">C</span> abundance of the deposit-feeder body tissues, or in the <span class="hlt">14</span><span class="hlt">C</span> abundance of their gut contents. The mean <span class="hlt">14</span><span class="hlt">C</span> abundance in the body tissues of the two sub-surface deposit feeders ( A</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21502794','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21502794"><span>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/servlets/purl/881059','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/881059"><span>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://adsabs.harvard.edu/abs/2012AGUFM.V23B2822T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.V23B2822T"><span>Towards 1‰ AMS <span class="hlt">14</span><span class="hlt">C</span> measurement precision at the Rafter Radiocarbon Laboratory</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Turnbull, J. C.; Baisden, T. T.; Zondervan, A.; Kaiser, J.; Brailsford, G.; Moss, R.</p> <p>2012-12-01</p> <p>The radiocarbon content of atmospheric CO2 (Δ14CO2) is an increasingly important tracer used to quantify the different sources of CO2 in the atmosphere. Due to the absence of <span class="hlt">14</span><span class="hlt">C</span> in fossil fuels, 14CO2 is perhaps the best way to quantify recently added fossil fuel CO2 in the atmosphere. The sea-air CO2 flux also has Δ<span class="hlt">14</span><span class="hlt">C</span> different from the atmosphere, so Δ14CO2 observations can be used to examine the one-way gross CO2 flux out of the oceans. Each one part per million (ppm) of fossil fuel CO2 added to the atmosphere decreases Δ14CO2 by about 2.6‰, and fossil fuel CO2 enhancements are typically in the range of a few ppm. The detection capability is therefore strongly influenced by the precision of <span class="hlt">14</span><span class="hlt">C</span> measurements. The World Meteorological Organization recommends a goal of 1‰ <span class="hlt">14</span><span class="hlt">C</span> precision, and Δ14CO2 measurements can currently be made to slightly better than 2‰ at several facilities. New Zealand has a long history of atmospheric Δ14CO2 measurements, starting in Wellington in 1955. Rafter lab recently obtained a new accelerator mass spectrometer (AMS) and developed a new graphitization system. A major focus emerging from the upgrade is the opportunity to expand the high precision atmospheric Δ14CO2 capability. Results from the first year of measurements indicate 1.3‰ repeatability on modern atmospheric CO2 in samples as small as one liter of whole air, a significant improvement over previously reported AMS <span class="hlt">14</span><span class="hlt">C</span> repeatability. We use new measurements from the long-term Baring Head Δ14CO2 record demonstrate the utility of this new high precision capability in interpreting atmospheric signals. We will report on development of graphitization procedures and AMS methodology which allow us to achieve this precision. Progress towards 1‰ precision will be discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.B31A0315C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.B31A0315C"><span>Assessment of <span class="hlt">14</span><span class="hlt">C</span> AMS dating of phytoliths as a new paleoenvironmental and archaeological tool</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Corbineau, R.; Alexandre, A. E.; Santos, G. M.; Reyerson, P. E.</p> <p>2011-12-01</p> <p><span class="hlt">14</span><span class="hlt">C</span> AMS analysis of occluded carbon in phytoliths (phytC) is a promising dating tool for palaeoenvironmental and archaeological studies. In order to assess the accuracy of this method, different tests were recently carried out on large phytolith concentrates of phytC samples extracted from soils and harvested plants, in association with blank samples of SiO2 powder to check the absence of carbon contamination during the treatments. Despite this precaution, <span class="hlt">14</span><span class="hlt">C</span> values from recent harvested plants were inexplicably old (2 - 8 ka years BP). Nevertheless, we noticed that many chemical extraction protocols that were used did not lead to samples totally free of organic matter. In order to tackle this problem, and as a first step, the efficiency of common extraction protocols from the literature were tested. Samples were analyzed by SEM/EDX in order to assess the purity of the siliceous material following extraction. As a result of these tests, a new extraction protocol combining acid digestion, oxidation and dry ashing to acquire pure samples of phytoliths from harvested plants is proposed. In a second step, modern and well dated archaeological materials (harvested plants grown within a FACE experiment and plant residues from a 17th century French mummy) were analyzed in <span class="hlt">14</span><span class="hlt">C</span>-AMS. Results should allow either to demonstrate the reliability of <span class="hlt">14</span><span class="hlt">C</span>-AMS analysis of phytolith occluded carbon as a dating tool or trigger further investigations of possible sources of old occluded carbon in phytoliths if the <span class="hlt">14</span><span class="hlt">C</span> ages are still older than expected.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/346826','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/346826"><span>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('https://www.osti.gov/scitech/biblio/655400','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/655400"><span>Fate and stability of nonextractable residues of [{sup <span class="hlt">14</span>}<span class="hlt">C</span>]PAH in contaminated soils under environmental stress conditions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Eschenbach, A.; Mahro, B.; Wienberg, R.</p> <p>1998-09-01</p> <p>It has been recognized during recent years that polycyclic aromatic hydrocarbons (PAH) may form nonextractable residues in soil and that this process may be stimulated by microbial activities. To use that process intentionally for soil bioremediation, one must ensure that the formed nonextractable PAH residues will not be released from the soil on the long run. The long-term stability of four different nonextractable [{sup <span class="hlt">14</span>}<span class="hlt">C</span>]PAH residues ([{sup <span class="hlt">14</span>}<span class="hlt">C</span>]naphthalene, [{sup <span class="hlt">14</span>}<span class="hlt">C</span>]anthracene, [{sup <span class="hlt">14</span>}<span class="hlt">C</span>]pyrene, and [{sup <span class="hlt">14</span>}<span class="hlt">C</span>]benzo[a]pyrene) was therefore monitored under different ecological stress conditions. It was found that a considerable fraction of the total [{sup <span class="hlt">14</span>}<span class="hlt">C</span>]PAH residues could be released as {sup 14}CO{sub 2} from the soil being partly due to a biogenic reduction of the nonextractable {sup <span class="hlt">14</span>}<span class="hlt">C</span> residue fraction. The turnover of this fraction was comparable to the natural turnover rate for humic substances. Neither the addition of humus-degrading microorganisms nor a mechanical stress treatment of the soil structure by freezing and thawing led to a mobilization of the nonextractable [{sup <span class="hlt">14</span>}<span class="hlt">C</span>]PAH residues. However, a significant mobilization of the nonextractable {sup <span class="hlt">14</span>}<span class="hlt">C</span> activity occurred when EDTA was added to the soil. The metal-organic soil complexes were destabilized by this complexing agent and released {sup <span class="hlt">14</span>}<span class="hlt">C</span> activity that was attached to colloidal or dissolved organic matter.</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>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('http://www.osti.gov/scitech/servlets/purl/10650','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10650"><span>Status of cross-section data for gas production from vanadium and {sup <span class="hlt">26</span>}<span class="hlt">AL</span> from silicon carbide in a D-T fusion reactor.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gomes, I. C.</p> <p>1998-08-11</p> <p>Current designs of fusion-reactor systems seek to use radiation-resistant, low-activation materials that support long service lifetimes and minimize radioactive-waste problems after decommissioning. Reliable assessment of fusion materials performance requires accurate neutron-reaction cross sections and radioactive-decay constants. The problem areas usually involve cross sections since decay parameters tend to be better known. The present study was motivated by two specific questions: (i) Why are the {sup 51}V(n,np){sup 50}Ti cross section values in the ENDF/B-VI library so large (a gas production issue)? (ii) How well known are the cross sections associated with producing 7.4 x 10{sup 5} y {sup <span class="hlt">26</span>}<span class="hlt">Al</span> in silicon carbide by the process {sup 28}Si(n,np+d){sup 27} Al(n,2n){sup <span class="hlt">26</span>}<span class="hlt">Al</span> (a long-lived radioactivity issue)? The energy range 14-15 MeV of the D-T fusion neutrons is emphasized. Cross-section error bars are needed so that uncertainties in the gas and radioactivity generated over the lifetime of a reactor can be estimated. We address this issue by comparing values obtained from prominent evaluated cross-section libraries. Small differences between independent evaluations indicate that a physical quantity is well known while the opposite signals a problem. Hydrogen from {sup 51}V(n,p){sup 51}Ti and helium from {sup 51}V(n,{alpha}){sup 48}Sc are also important sources of gas in vanadium, so they too were examined. We conclude that {sup 51}V(n,p){sup 51}Ti is adequately known but {sup 51}V(n,np+d){sup 50}Ti is not. The status for helium generation data is quite good. Due to recent experimental work, {sup 27}Al(n,2n){sup <span class="hlt">26</span>}<span class="hlt">Al</span> seems to be fairly well known. However, the situation for {sup 28}Si(n,np+d){sup 27}Al remains unsatisfactory.</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>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('https://www.ncbi.nlm.nih.gov/pubmed/10422252','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10422252"><span>A model for the formation and degradation of bound residues of the herbicide <span class="hlt">14</span><span class="hlt">C</span>-isoproturon 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>Reuter, S; Ilim, M; Munch, J C; Andreux, F; Scheunert, I</p> <p>1999-08-01</p> <p>The humic monomer catechol was reacted with <span class="hlt">14</span><span class="hlt">C</span>-isoproturon and some of its metabolites, including <span class="hlt">14</span><span class="hlt">C</span>-4-isopropylaniline, in aqueous solution under a stream of oxygen. Only in the case of <span class="hlt">14</span><span class="hlt">C</span>-4-isopropylaniline, incorporation in oligomers, in fulvic acid-like polymers, and in humic acid-like polymers was observed. The main oligomer was identified by mass spectrometry as 4,5-bis-(4-isopropylphenylamino)-3,5-cyclohexadiene-1,2-dione. Oligomers and polymers containing bound <span class="hlt">14</span><span class="hlt">C</span>-4-isopropylaniline were subjected to biodegradation studies in a loamy agricultural soil during 55 days by quantifying 14CO2 evolved. In all cases, significant mineralization rates could be determined, which, however, were much smaller than those of free <span class="hlt">14</span><span class="hlt">C</span>-4-isoproturon and free <span class="hlt">14</span><span class="hlt">C</span>-4-isopropylaniline in the same soil.</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>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('https://ntrs.nasa.gov/search.jsp?R=20040112229&hterms=Abdomen&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DAbdomen','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040112229&hterms=Abdomen&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DAbdomen"><span>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> </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('https://www.ncbi.nlm.nih.gov/pubmed/27387810','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27387810"><span>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://adsabs.harvard.edu/abs/2017Geomo.281...53D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017Geomo.281...53D"><span>Early to Late Pleistocene history of debris-flow fan evolution in western Death Valley (California) using 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>Dühnforth, Miriam; Densmore, Alexander L.; Ivy-Ochs, Susan; Allen, Philip; Kubik, Peter W.</p> <p>2017-03-01</p> <p>Debris-flow fans with depositional records over several 105 years may be useful archives for the understanding of fan construction by debris flows and post-depositional surface modification over long timescales. Reading these archives, however, requires that we establish the temporal and spatial pattern of debris-flow activity over time. We used a combination of geomorphic mapping of fan surface characteristics, digital topographic analysis, and cosmogenic radionuclide dating using 10Be and <span class="hlt">26</span><span class="hlt">Al</span> to study the evolution of the Warm Springs fan on the west side of southern Death Valley, California. The 10Be concentrations yield dates that vary from 989 ± 43 to 595 ± 17 ka on the proximal fan and between 369 ± 13 and 125 ± 5 ka on distal fan surfaces. The interpretation of these results as true depositional ages though is complicated by high inheritance with a minimum of 65 ka measured at the catchment outlet and of at least 125 ka at the distal fan. Results from the <span class="hlt">26</span><span class="hlt">Al</span> measurements suggest that most sample locations on the fan surfaces underwent simple exposure and were not affected by complex histories of burial and re-exposure. This implies that Warm Springs fan is a relatively stable landform that underwent several 105 years of fan aggradation before fan head incision caused abandonment of the proximal and central fan surfaces and deposition continued on a younger unit at the distal fan. We show that the primary depositional debris-flow morphology is eliminated over a time scale of less than 105 years, which prevents the delineation of individual debris flows as well as the precise reconstruction of lateral shifts in deposition as we find it on younger debris-flow fans. Secondary post-depositional processes control subsequent evolution of surface morphology with the dissection of planar surfaces while smoothing of convex-up interfluves between incised channels continues through time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5561033','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5561033"><span>( 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.osti.gov/scitech/biblio/6038389','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6038389"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/14500785','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14500785"><span>The origin of war: new <span class="hlt">14</span><span class="hlt">C</span> dates from ancient Mexico.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Flannery, Kent V; Marcus, Joyce</p> <p>2003-09-30</p> <p>New <span class="hlt">14</span><span class="hlt">C</span> dates from archaeological sites in Oaxaca, Mexico, support R. C. Kelly's observation that intervillage raiding may begin as soon as a region has segmentary societies. The oldest defensive palisade dates to 3260-3160 B.P. in conventional radiocarbon years, only a few centuries after village life was established. Over the next millennium raiding evolved into war, with residences and temples burned, captives killed, and populations moving to defensible hills. <span class="hlt">14</span><span class="hlt">C</span> dates are now available for the first use of hieroglyphic writing to record a captive's name, military victories leading to the consolidation of the Zapotec state, the first skull rack, and the building of a fortress in conquered territory.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18830702','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18830702"><span>The dynamic transfer of 3H and <span class="hlt">14</span><span class="hlt">C</span> in mammals: a proposed generic model.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Galeriu, D; Melintescu, A; Beresford, N A; Takeda, H; Crout, N M J</p> <p>2009-02-01</p> <p>Associated with the present debate regarding the potential revival of nuclear energy there is an increased interest in assessing the radiological risk to the public and also the environment. Tritium and (<span class="hlt">14</span>)<span class="hlt">C</span> are key radionuclides of interest in many circumstances (e.g. heavy water reactors, waste storage and fusion reactors). Because the stable analogues of these two radionuclides are integral to most biological compounds, their modelling should follow general principles from life sciences. In this paper, a model of the dynamics of (<span class="hlt">14</span>)<span class="hlt">C</span> and (3)H in mammals is proposed on the basis of metabolic understanding and of, as far as possible, readily available data (e.g. for organ composition and metabolism). The model is described together with validation tests (without calibration) for a range of farm animals. Despite simplifications, the model tests are encouraging for a range of animal types and products (tissues and milk), and further improvements are suggested.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5098188','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5098188"><span>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://pubs.er.usgs.gov/publication/70020892','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70020892"><span>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('https://www.osti.gov/scitech/biblio/5528528','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5528528"><span>Effect of chlorphentermine on incorporation of (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)choline in the rat lung phospholipids</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gonmori, K.; Morita, T.; Mehendale, H.M.</p> <p>1986-03-01</p> <p>The effect of chlorphentermine (CP) treatment (50 mg/kg/day, per os (po)) on the incorporation of (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)choline into rat lung phospholipid was studied. Total phospholipid content was increased 2.0-fold and 1.7-fold after seven and /sup 14/ days, respectively, compared with the pair-fed rats. The incorporation of (<span class="hlt">14</span><span class="hlt">C</span>)choline into phosphatidylcholine (PC) was significantly inhibited by either seven or 14 days of CP treatment. Nevertheless, the PC content was significantly increased by day 7 and stayed elevated at day 14 of CP treatment. Choline and phosphorylcholine contents were significantly decreased by the CP treatment. These results suggest that the higher accumulation of PC is due to inhibition of enzymes involved in the hydrolysis of phospholipids rather than to a stimulation of the phospholipid synthesis.</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>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://adsabs.harvard.edu/abs/2006QuRes..65..508P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006QuRes..65..508P"><span>Suitability of biogenic carbonate of Lithospermum fruits for <span class="hlt">14</span><span class="hlt">C</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>Pustovoytov, Konstantin; Riehl, Simone</p> <p>2006-05-01</p> <p>Lithospermum (Boraginaceae) belongs to a small group of plant taxa that accumulate biogenic carbonate in their fruits. In this genus, carbonate incrustations form in the cells of the epidermis and sclerenchyma of the pericarp. Fossil Lithospermum fruits (nutlets) with well-preserved calcified tissues commonly occur in Quaternary sediments and cultural layers. We tested the suitability of biogenic carbonate of Lithospermum fruits for radiocarbon dating using a total of 15 AMS measurement results from four modern and 11 fossil samples. The <span class="hlt">14</span><span class="hlt">C</span> data from modern samples suggest that Lithospermum utilises only atmospheric carbon to synthesise calcite in the nutlets. In general, the ages determined through <span class="hlt">14</span><span class="hlt">C</span> dating of fossil fruitscorresponded well with the absolute-age intervals for archaeological sites over the last 5000 yr. Biogenic carbonate of Lithospermum fruits, like that of Celtis, represents a new source of chronological information for late Quaternary studies.</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>{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('https://www.ncbi.nlm.nih.gov/pubmed/3930562','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/3930562"><span>Production of <span class="hlt">14</span><span class="hlt">C</span>-labeled gas in BACTEC Neisseria Differentiation kits by Neisseria cinerea.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Boyce, J M; Mitchell, E B; Knapp, J S; Buttke, T M</p> <p>1985-09-01</p> <p>Six strains of Neisseria cinerea were tested in BACTEC Neisseria Differentiation kits (Johnston Laboratories, Inc., Towson, Md.), and all yielded positive glucose growth indices and negative maltose and fructose growth indices. These results were similar to those achieved with Neisseria gonorrhoeae. However, most of the N. cinerea isolates tested yielded 3-h glucose growth indices that were lower than those obtained with gonococci. <span class="hlt">14</span><span class="hlt">C</span>-labeled gas was produced significantly faster (P less than 0.02) by N. gonorrhoeae than by N. cinerea. Additional studies suggested that the <span class="hlt">14</span><span class="hlt">C</span>-labeled gas produced by N. cinerea was carbon dioxide. N. cinerea strains were similar to Branhamella catarrhalis strains because both species failed to produce detectable acid from glucose, maltose, sucrose, fructose, and lactose in cysteine-tryptic agar media. However, in contrast to N. cinerea strains, B. catarrhalis strains did not metabolize glucose in BACTEC Neisseria Differentiation kits.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24128522','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24128522"><span>Biocomponent determination in vinegars with the help of <span class="hlt">14</span><span class="hlt">C</span> measured by liquid scintillation counting.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tudyka, Konrad; Pawlyta, Jacek</p> <p>2014-02-15</p> <p>This article presents a method of carbon extraction from vinegar used in preparation of liquid scintillation counting cocktails for measurements of low (<span class="hlt">14</span>)<span class="hlt">C</span> radioactivity. The presented method is relatively fast and can be used to produce liquid scintillation cocktails e.g., via benzene synthesis. In this work we present specific radiocarbon radioactivity determinations and based on them estimation of bio product content for five commercially available vinegars. All investigated vinegars are likely produced from plants in fermentation process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5639496','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5639496"><span>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.osti.gov/scitech/biblio/7188081','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/7188081"><span>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('https://www.osti.gov/scitech/biblio/5799124','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5799124"><span>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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AIPC.1351..357M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AIPC.1351..357M"><span>Internal Dosimetry of a Chylomicron-like Emulsion Labeled with <span class="hlt">14</span><span class="hlt">C</span>-CE in Humans</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marcato, Larissa A.; Carvalho, Diego V. S.; Hamada, Margarida M.; Vinagre, Carmen G.; Maranhão, Raul C.; de Mesquita, Carlos H.</p> <p>2011-08-01</p> <p>This paper estimates the value of the effective equivalent dose in humans due to intravenous injection of chylomicron-like emulsion radiolabeled with <span class="hlt">14</span><span class="hlt">C</span>-CE. A kinetic model for the chylomicron-like emulsion in human body was proposed. The removal parameters of chylomicron-like emulsion from the plasma were evaluated by compartimental analysis. Radiometric doses were calculated using AnaComp software and the MIRD formalism.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16003827','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16003827"><span>Spatial variability in <span class="hlt">14</span><span class="hlt">C</span>-herbicide degradation in surface and subsurface soils.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Charnay, Marie-Paule; Tuis, Sébastien; Coquet, Yves; Barriuso, Enrique</p> <p>2005-09-01</p> <p>The spatial variability in mineralization of atrazine, isoproturon and metamitron in soil and subsoil samples taken from a 135-ha catchment in north France was studied. Fifty-one samples from the top layer were taken to represent exhaustively the 31 agricultural fields and 21 soil types of the catchment. Sixteen additional samples were collected between depths of 0.7 and 10 m to represent the major geological materials encountered in the vadose zone of the catchment. All these samples were incubated with <span class="hlt">14</span><span class="hlt">C</span>-labelled atrazine under laboratory conditions at 28 degrees C. Fourteen selected surface samples which exhibited distinctly different behaviour for atrazine dissipation (including sorption and mineralization) were incubated with <span class="hlt">14</span><span class="hlt">C</span>-isoproturon and <span class="hlt">14</span><span class="hlt">C</span>-metamitron. Overall soil microbial activity and specific herbicide degradation activities were monitored during the incubations through measurements of total carbon dioxide and <span class="hlt">14</span><span class="hlt">C</span>-carbon dioxide respectively. At the end of the incubations, extractable and non-extractable (bound) residues remaining in soils were measured. Variability of herbicide dissipation half-life in soil surface samples was lower for atrazine and metamitron (CV < 12%) than for isoproturon (CV = 46%). The main contributor to the isoproturon dissipation variability was the variability of the extractable residues. For the other herbicides, spatial variability was mainly related to the variability of their mineralization. In all cases, herbicide mineralization half-lives showed higher variability than those of dissipation. Sorption or physicochemical soil properties could not explain atrazine and isoproturon degradation, whose main factors were probably directly related to the dynamics of the specific microbial degradation activity. In contrast, variability of metamitron degradation was significantly correlated to sorption coefficient (K(d)) through correlation with the sorptive soil components, organic matter and clay. Herbicide degradation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/7192806','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/7192806"><span>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> </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('https://www.ncbi.nlm.nih.gov/pubmed/7271380','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/7271380"><span>Whole-body localization of <span class="hlt">14</span><span class="hlt">C</span>-tocopheryl acetate in the rat following oral administration.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fand, I; McNally, W P</p> <p>1981-03-01</p> <p>The whole-body localization of dl-alpha-[3, 4-<span class="hlt">14</span><span class="hlt">C</span>2]-tocopheryl acetate was examined in the rat for intervals ranging between 12-96 hr following administration of a single oral dose. Quantitative evaluation of the macroautoradiograms revealed a rapid removal of <span class="hlt">14</span><span class="hlt">C</span>-vitamin E equivalents from the blood and gut and their accumulation in body tissues. When the densitometric data were expressed as dpm/mm2, the values for radioactivity uptake by the adrenal cortex were systematically the highest of all tissues examined for all time periods. At 12-96 hr after dosing, high activity was noted in spleen, bone marrow, liver, lymph nodes and fat; moderate activity was observed in myocardium, lung, gastric mucosa, pituitary, blood, hair follicles, Harder's gland and nasal mucosa; low values were found in brain, skeletal muscle and spinal cord. The nearly complete exclusion of radiovitamin E from the brain and its localization to the choroid plexus implied the operation of a blood-brain barrier. Labeled vitamin E uptake in brain, salivary glands and skeletal muscle was essentially linear and increased with time over 12-96 hr. For both early and late sacrifice periods, a differential pattern of <span class="hlt">14</span><span class="hlt">C</span>-radioactivity uptake was observed with the pituitary, where the pars nervosa exhibited 2.8 times greater activity than the pars distalis. The significance of the findings is discussed in relation to the suggested role of vitamin E in pituitary-adrenal functions, hemopoiesis and oral physiology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21698547','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21698547"><span>Transfer of <span class="hlt">14</span><span class="hlt">C</span>-photosynthate to the sporocarp of an ectomycorrhizal fungus Laccaria amethystina.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Teramoto, Munemasa; Wu, Bingyun; Hogetsu, Taizo</p> <p>2012-04-01</p> <p>Sporocarps of ectomycorrhizal fungi are strong carbon sinks for the source in host trees, but the details of carbon transfer from the host to the sporocarp are unknown. In this study, single seedlings of Japanese red pine (Pinus densiflora) colonised by Laccaria amethystina were grown on floral foam plates fitted in rhizoboxes, resulting in fruiting on the substrate. The seedlings were photosynthetically labelled with (14)CO(2); (<span class="hlt">14</span>)<span class="hlt">C</span>-labelled photosynthate transfer from leaves to sporocarps was then chased using a time-course autoradiography technique. (<span class="hlt">14</span>)<span class="hlt">C</span> was transferred to healthy, fresh sporocarps in a purple colour ranging from primordial to elongate sporocarps, but hardly to senesced ones that had faded to white or grey, or browned. This suggested that C is transferred only to physiologically active sporocarps. Two seedlings associated with a growing sporocarp were labelled again 7 and 16 days after the first labelling, respectively. (<span class="hlt">14</span>)<span class="hlt">C</span> accumulation in the sporocarps rose in a stepwise manner after the second labelling, indicating that sporocarps mainly used recently rather than previously photosynthesised C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5450915','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5450915"><span>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> <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>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('https://www.ncbi.nlm.nih.gov/pubmed/27038208','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27038208"><span>Enantioselective absorption and transformation of a novel chiral neonicotinoid [(<span class="hlt">14</span>)<span class="hlt">C</span>]-cycloxaprid 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>Wu, Chengchen; Huang, Lei; Tang, Shenghua; Li, Zhong; Ye, Qingfu</p> <p>2016-06-01</p> <p>Neonicotinoid pesticides caused hazardous effects on pollinators and aquatic ecosystem. The new developed chiral cis-neonicotinoid cycloxaprid(CYC) is a highly potent substitute for low toxicity to bees and high efficiency on target-insects, but little is known about the metabolic dynamics of racemic CYC and its 2 enantiomers(SR and RS) in animal models. In this study, chiral separation of (<span class="hlt">14</span>)<span class="hlt">C</span>-labeled racemic CYC was performed in high-performance liquid chromatography under optimal conditions. For the first time that the stereoselectivity of the chiral neonicotinoid insecticide CYC was exhibited in rats after single dose oral administration using (<span class="hlt">14</span>)<span class="hlt">C</span>-labeled isotope trace technique. Enantioselective behaviors of racemic CYC, SR and RS were observed in blood metabolism, tissue distribution and excretion. The major deposition of (<span class="hlt">14</span>)<span class="hlt">C</span> were found in liver, lung, kidney and heart. After 24 h, skin and fat showed a strong bioaccumulation effect, and total excreted urine and feces of CYC, SR and RS were 50.4%, 59.7% and 74.5%, respectively. Enantiomer RS had the fastest absorption and elimination rates, and it was least bioaccumulated in rats. The results provide scientific basis and practical techniques for environmental risk assessment of chiral pesticides, especially neonicotinoids.</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>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('https://www.osti.gov/scitech/biblio/6749103','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6749103"><span>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('https://www.osti.gov/scitech/biblio/5551986','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5551986"><span>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('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5372693','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5372693"><span>In vivo degradation of <span class="hlt">14</span><span class="hlt">C</span>-labeled porcine dermis biologic scaffold</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Carey, Lisa E.; Dearth, Christopher L.; Johnson, Scott A.; Londono, Ricardo; Medberry, Christopher J.; Daly, Kerry A.; Badylak, Stephen F.</p> <p>2017-01-01</p> <p>Biologic scaffold materials are used for repair and reconstruction of injured or missing tissues. Such materials are often composed of allogeneic or xenogeneic extracellular matrix (ECM) manufactured by decellularization of source tissue, such as dermis. Dermal ECM (D-ECM) has been observed to degrade and remodel in vivo more slowly than other biologic scaffold materials, such as small intestinal submucosa (SIS-ECM). Histologic examination is a common method for evaluating material degradation, but it lacks sensitivity and is subject to observer bias. Utilization of <span class="hlt">14</span><span class="hlt">C</span>-proline labeled ECM is a quantitative alternative for measuring degradation of ECM scaffolds. Using both methods, the amount of degradation of D-ECM and SIS-ECM was determined at 2, 4, and 24 weeks post-implantation in a rodent model. Results utilizing <span class="hlt">14</span><span class="hlt">C</span> liquid scintillation counting (LSC) analysis showed distinct differences in degradation at the three time points. D-ECM material in situ stayed the same at 76% remaining from 2 to 4 weeks post-implantation, and then decreased to 44% remaining at 24 weeks. In the same time period, implanted SIS-ECM material decreased from 72% to 13% to 0%. Visual examination of device degradation by histology overestimated degradation at 2 weeks and underestimated device degradation at 24 weeks, compared to the <span class="hlt">14</span><span class="hlt">C</span> method. PMID:24997479</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5442380','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5442380"><span>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('https://www.ncbi.nlm.nih.gov/pubmed/21083255','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21083255"><span>Accelerator mass spectrometry best practices for accuracy and precision in bioanalytical (<span class="hlt">14</span>)<span class="hlt">C</span> measurements.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Vogel, John S; Giacomo, Jason A; Schulze-König, Tim; Keck, Bradly D; Lohstroh, Peter; Dueker, Stephen</p> <p>2010-03-01</p> <p>Accelerator mass spectrometers have an energy acceleration and charge exchange between mass definition stages to destroy molecular isobars and allow single ion counting of long-lived isotopes such as (<span class="hlt">14</span>)<span class="hlt">C</span> (t½=5370 years.). 'Low' voltage accelerations to 200 kV allow laboratory-sized accelerator mass spectrometers instruments for bioanalytical quantitation of (<span class="hlt">14</span>)<span class="hlt">C</span> to 2-3% precision and accuracy in isolated biochemical fractions. After demonstrating this accuracy and precision for our new accelerator mass spectrometer, we discuss the critical aspects of maintaining quantitative accuracy from the defined biological fraction to the accelerator mass spectrometry quantitation. These aspects include sufficient sample mass for routine rapid sample preparation, isotope dilution to assure this mass, isolation of the carbon from other sample combustion gasses and use of high-efficiency biochemical separations. This review seeks to address a bioanalytical audience, who should know that high accuracy data of physiochemical processes within living human subjects are available, as long as a (<span class="hlt">14</span>)<span class="hlt">C</span> quantitation can be made indicative of the physiochemistry of interest.</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>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://pubs.er.usgs.gov/publication/70022282','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70022282"><span>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.osti.gov/scitech/biblio/948849','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/948849"><span>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/2014DSRI...91...94P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014DSRI...91...94P"><span>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('http://adsabs.harvard.edu/abs/2013EGUGA..15.7595B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.7595B"><span>Source and age of carbon in peatland surface waters: new insights from <span class="hlt">14</span><span class="hlt">C</span> analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Billett, Michael; Garnett, Mark; Dinsmore, Kerry; Leith, Fraser</p> <p>2013-04-01</p> <p>Peatlands are a significant source of carbon to the aquatic environment which is increasingly being recognised as an important flux pathway (both lateral and vertical) in total landscape carbon budgets. Determining the source and age of the carbon (in its various forms) is a key step to understanding the stability of peatland systems as well as the connectivity between the soil carbon pool and the freshwater environment. Novel analytical and sampling methods using molecular sieves have been developed for (1) within-stream, in situ sampling of CO2 in the field and (2) for the removal/separation of CO2 in the laboratory prior to <span class="hlt">14</span><span class="hlt">C</span> analysis of CH4. Here we present dual isotope (δ13C and <span class="hlt">14</span><span class="hlt">C</span>) data from freshwater systems in UK and Finnish peatlands to show that significant differences exist in the source and age of CO2, DOC (dissolved organic carbon) and POC (particulate organic carbon). Individual peatlands clearly differ in terms of their isotopic freshwater signature, suggesting that carbon cycling may be "tighter" in some systems compared to others. We have also measured the isotopic signature of different C species in peatland pipes, which appear to be able to tap carbon from different peat depths. This suggests that carbon cycling and transport within "piped-peatlands" may be more complex than previously thought. Some of our most recent work has focussed on the development of a method to measure the <span class="hlt">14</span><span class="hlt">C</span> component of CH4 in freshwaters. Initial results suggest that CH4 in peatland streams is significantly older than CO2 and derived from a much deeper source. We have also shown that the age (but not the source) of dissolved CO2 changes over the hydrological year in response to seasonal changes in discharge and temperature. Radiocarbon measurements in the peat-riparian-stream system suggest that a significant degree of connectivity exists in terms of C transport and cycling, although the degree of connectivity differs for individual C species. In summary, <span class="hlt">14</span><span class="hlt">C</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6698760','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6698760"><span>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>[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('https://www.ncbi.nlm.nih.gov/pubmed/25464038','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25464038"><span>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/servlets/purl/967755','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/967755"><span>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> </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('https://www.osti.gov/scitech/biblio/20863727','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20863727"><span>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>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/15110362','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15110362"><span>Measurement of depth distributions of (3)H and (<span class="hlt">14</span>)<span class="hlt">C</span> induced in concrete shielding of an electron accelerator facility.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Endo, Akira; Harada, Yasunori; Kawasaki, Katsuya; Kikuchi, Masamitsu</p> <p>2004-06-01</p> <p>The estimation of radioactivity induced in concrete shielding is important for the decommissioning of accelerator facilities. Concentrations of (3)H and (<span class="hlt">14</span>)<span class="hlt">C</span> in the concrete shielding of an electron linear accelerator were measured, and the depth distributions of (3)H and (<span class="hlt">14</span>)<span class="hlt">C</span> and gamma-ray emitters were discussed in relation to their formation reactions.</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>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('https://www.ncbi.nlm.nih.gov/pubmed/24497100','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24497100"><span>Lateral movement out of the sieve tubes and its effect on the (<span class="hlt">14</span>)<span class="hlt">C</span> translocation profile in Helianthus seedlings.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Whittle, C M</p> <p>1970-09-01</p> <p>The profile of (<span class="hlt">14</span>)<span class="hlt">C</span>, that is the plot of log (radioactivity) against distance, down the stem of Helianthus seedlings was studied over the course of the first hour after feeding (<span class="hlt">14</span>)<span class="hlt">C</span> to a leaf. These seedlings are shown to accumulate a large proportion of the total (<span class="hlt">14</span>)<span class="hlt">C</span> present in the stem in an ethanol insoluble form. The effect of this accumulation on the shape of the profile is considered. The steep advancing front is similar in shape and behaviour in Helianthus and in plants which show little accumulation of insoluble (<span class="hlt">14</span>)<span class="hlt">C</span> but the later part of the profile is different in the two groups. This difference would be expected if lateral movement of (<span class="hlt">14</span>)<span class="hlt">C</span> out of the translocation stream were mainly irreversible in these Helianthus plants but mainly reversible in plants of the other group.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFMPP32B0298W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFMPP32B0298W"><span>Changes in Atmospheric <span class="hlt">14</span><span class="hlt">C</span> Between 55 and 42 ky BP Recorded in a Stalagmite From Socotra Island, Indian Ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Weyhenmeyer, C. E.; Burns, S. J.; Fleitmann, D.; Kramers, J. D.; Matter, A.; Waber, H. N.; Reimer, P. J.</p> <p>2003-12-01</p> <p>A record of atmospheric radiocarbon (<span class="hlt">14</span><span class="hlt">C</span>) variations for a part of the last glacial period was obtained from a 1.7 m long stalagmite, M1-2, from Socotra Island in the Indian Ocean. The stalagmite radiocarbon values were corrected for <span class="hlt">14</span><span class="hlt">C</span>-free carbon added by water-rock interaction (dead carbon fraction), by using del 13C values of the calcite as a constraint. An age-depth model was developed from 25 high-precision U/Th measurements. The base of the stalagmite dates to 54.7 ky BP and it stopped growing around 42.2 ky BP. The difference between U/Th and <span class="hlt">14</span><span class="hlt">C</span> ages shows a smooth, steady increase from about 5,000 years at the base of the stalagmite to about 8,000 years at its top. Correspondingly, Delta <span class="hlt">14</span><span class="hlt">C</span> values increase from 500 per mil to about 1300 per mil, which indicates that concentrations of atmospheric <span class="hlt">14</span><span class="hlt">C</span> steadily increased between 55 and 42 yr BP. The record from Socotra Island does not show the large and rapid D<span class="hlt">14</span><span class="hlt">C</span> changes previously recorded in a stalagmite from the Bahamas (Beck et al, Science 2001). The D<span class="hlt">14</span><span class="hlt">C</span> values estimated from M1-2 are significantly higher than those estimated from a marine <span class="hlt">14</span><span class="hlt">C</span> record (foraminifera) from Cariaco Basin for the same time period (Hughen et al. in prep). In the latter, D<span class="hlt">14</span><span class="hlt">C</span> values decrease to near 0 at about 44 ky BP. The most likely reason for this discrepancy are the two different time scales used; the Cariaco Basin is matched to the GISP2 timescale, which is approximately 5000 years younger than indicated by the stalagmite U/Th chronology (Burns et al, Science 2003). When the Cariaco basin record is adjusted to the M1-2 timescale, the D<span class="hlt">14</span><span class="hlt">C</span> values for both datasets are similar.</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>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> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.5509D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.5509D"><span>Depth distribution of soil organic carbon fractions and AMS <span class="hlt">14</span><span class="hlt">C</span> concentrations at different landscape positions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dlugoß, V.; Fiener, P.; Schneider, K.</p> <p>2012-04-01</p> <p>On sloped arable land soil redistribution has a great impact on spatial patterns of soil organic carbon (SOC) stocks and on the lateral and vertical carbon fluxes between soil and atmosphere. While most studies focus on total SOC, the investigation of the impact of soil redistribution on SOC fractions and thus on different SOC quality can improve the knowledge about the processes controlling an erosion induced C sink or source. Some studies indicate that the labile SOC pool might be preferentially transported by water erosion, however others indicate that black carbon being considered as an inert pool is preferentially redistributed. Preferential erosion and/or deposition of specific SOC fractions must lead to a spatial differentiation of the SOC pool composition in areas prone to erosion. In this study we analysed differences in the depth distribution of particle-size SOC fractions and AMS <span class="hlt">14</span><span class="hlt">C</span> concentrations in relation to these fractions at different slope positions within an arable field in western Germany. Based on modelled soil redistribution, two soil profiles representing depositional, erosional and reference (with ignorable erosion or deposition) sites were analysed. Soil cores were taken to a maximum depth of 1.6 m and were divided into 0.05 m increments except for the actual tillage depth (0-0.15 m). For every second depth increment starting with the topsoil layer total SOC, particle-size SOC fractions and AMS <span class="hlt">14</span><span class="hlt">C</span> concentrations were determined. The fractionation scheme of Amelung et al. (1998) was applied resulting in three particulate organic carbon fractions (POC 1: 250 - 2000 µm, POC 2: 53-250 µm, POC 3: 20 -53 µm) and the remaining fine sized fraction (< 20 µm). Combining POC 1 and 2, which are often assumed to represent the labile carbon pool shows a decline of SOC in these fractions from reference to erosional to depositional sites. This indicates (i) a preferential detachment of these fractions at erosional sites, while (ii) the more</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..1511101Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..1511101Z"><span><span class="hlt">14</span><span class="hlt">C</span>-based Source Apportionment of Carbonaceous Aerosols in Switzerland for 2008 - 2012</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zotter, Peter; Ciobanu, Gabriela; Zhang, Yanlin; El-Haddad, Imad; Szidat, Sönke; Wacker, Lukas; Baltensperger, Urs; Prévôt, André</p> <p>2013-04-01</p> <p>Carbonaceous particles (total carbon, TC) are a major fraction of the fine aerosol and affect climate and human health. TC is classified into the sub-fractions elemental carbon (EC) and organic carbon (OC). EC originates only from fossil fuel combustion and biomass burning. OC can be emitted directly as primary organic aerosol from biogenic emissions, wood burning and fossil fuel combustion or can be formed in-situ in the atmosphere (secondary organic aerosol) (Szidat et al. 2006). Radiocarbon (<span class="hlt">14</span><span class="hlt">C</span>) analysis is a direct and quantitative tool for distinguishing fossil and non-fossil sources, since <span class="hlt">14</span><span class="hlt">C</span> in fossil fuels is completely depleted whereas other sources have a contemporary <span class="hlt">14</span><span class="hlt">C</span> level. This study presents source apportionment results from the winter season over a time period of 5 years (2007/2008-2011/2012) using <span class="hlt">14</span><span class="hlt">C</span> measurements on aerosol filters collected simultaneously at 16 air quality monitoring stations across Switzerland. For every year 5 winter smog episode days were selected from which filters from all stations were analyzed. To resolve a good spatial variability 11 stations north and 5 stations south of the Alps were selected. This <span class="hlt">14</span><span class="hlt">C</span> data set is unique around the world concerning the number of analyzed filters and the duration. The filter sampling was conducted using high volume samplers with PM10 inlets and a time resolution of 24h. Separation of OC and EC was carried out using the THEODORE system (Szidat et al. 2004) and a Sunset EC/OC analyzer (Zhang et al. 2012), respectively. The resulting CO2 was cryo-trapped and sealed in glass ampoules for <span class="hlt">14</span><span class="hlt">C</span> measurements, performed with the Mini Carbon Dating System MICADAS (Ruff et al. 2007) at the Swiss Federal Institute of Technology (ETH) Zürich. The results for non-fossil (NF) OC (5 year average) are 81% ± 10% for north and 85% ± 8% for south of the Alps. ECNF values range from 31% to 53% north and from 36% to 66% south of the Alps. Both, the OCNF and ECNF show higher values south of the Alps</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>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('https://www.osti.gov/scitech/biblio/6268333','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6268333"><span>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://www.osti.gov/scitech/servlets/purl/793636','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/793636"><span>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/2010EGUGA..12.4187H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.4187H"><span>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 mineralization of <span class="hlt">14</span><span class="hlt">C</span>-atrazine of 81% was observed in the atrazine untreated soil under slurry conditions. This observation might be due to a possible cross adaption of the microflora. These results could be attributed to an atrazine drift during application since the control samples were taken in an adjacent pear orchard with no atrazine application history. These results demonstrate an adaption of the microflora to mineralize atrazine rapidly. The formation of desorbable metabolites as well as the formation of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6184053','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6184053"><span>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.osti.gov/scitech/biblio/5802613','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5802613"><span>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('https://www.osti.gov/scitech/biblio/386957','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/386957"><span>Determination of the weak magnetism matrix element in {sup <span class="hlt">14</span>}<span class="hlt">C</span> beta decay</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zeuli, A.R.; Ahmad, I.; Coulter, K.P.; Greene, J.P.; Schiffer, J.P.; Freedman, S.J.; Fujikawa, B.K.; Mortara, J.L.</p> <p>1993-10-01</p> <p>Higher order beta decay matrix elements, such as weak magnetism, will introduce small departures (a shape factor) from the allowed beta decay electron energy spectrum. The value of the weak magnetism matrix element is predicted by the Conserved Vector Current (CVC) hypothesis and an experimental determination of the weak magnetism matrix element can be interpreted as a test of CVC. We have determined the weak magnetism matrix element from the {sup <span class="hlt">14</span>}<span class="hlt">C</span> shape factor, which was measured using an apparatus incorporating a high resolution solid state detector and a super conducting solenoid. The results of our measurement will be presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5702246','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5702246"><span>Accumulation and elimination of (9-/sup <span class="hlt">14</span>/<span class="hlt">C</span>)phenanthrene in the calico clam (Macrocallista maculata)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Solbakken, J.E.; Jeffrey, F.M.H.; Knap, A.H.; Palmork, K.H.</p> <p>1982-05-01</p> <p>The accumulation and elimination of radoactivity is studied after exposure of (9-/sup <span class="hlt">14</span>/<span class="hlt">C</span>) phenanthrene in various tissues in the calico clam (Macrocallista maculata). Results show that accumulation is highest in the lipid-rich hepatopancreas, and the elimination is very efficient compared to the horse mussel. The calico clam, which is a sand-dwelling organism, can easily come in contact with hydrocarbon contaminated sedments and might accumulate the hydrocarbons at different extents in various tissues. The efficient elimination, however, will prevent a lasting accumulation. (JMT)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21032666','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21032666"><span>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('https://www.osti.gov/scitech/biblio/5547981','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5547981"><span>Double labeling autoradiography. Cell kinetic studies with /sup 3/H- and /sup <span class="hlt">14</span>/<span class="hlt">C</span>-thymidine</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Schultze, B.</p> <p>1981-01-01</p> <p>Examples of the multiple applicability of the double labeling method with /sup 3/H- and /sup <span class="hlt">14</span>/<span class="hlt">C</span>-TdR are demonstrated. Double labeling with /sup 3/H- and /sup <span class="hlt">14</span>/<span class="hlt">C</span>-TdR makes it possible to determine the cycle and its phases with high precision by modifying the usual percent labeled mitoses method with a single injection of /sup 3/H-TdR. In addition, data is provided on the variances of the transit times through the cycle phases. For example, in the case of the jejunal crypt cells of the mouse, the transit times through successive cycle phases are uncorrelated. In the case of glial cells the double labeling method provides cell kinetic parameters despite the paucity of proliferating glial cells. In the adult untreated animal, glial cell mitoses are so rare that the percent labeled mitoses method can not be utilized. However, the S-phase duration can be measured by double labeling and the cycle time can be determined by the so-called method of labeled S phases. With the latter method the passage through the S phase of the /sup 3/H-TdR-labeled S phase cells can be registered by injecting /sup <span class="hlt">14</span>/<span class="hlt">C</span>-TdR at different time intervals following /sup 3/H-TdR application. In this way an S-phase duration of about 10 hr and a cycle time of about 20 hr was found for glial cells in the adult untreated mouse. An exchange of glial cells between the growth fraction and the nongrowth fraction has also been shown by double labeling. A quite different application of the double labeling method with 3H- and /sup <span class="hlt">14</span>/<span class="hlt">C</span>-TdR is the in vivo study of the cell cycle phase-specific effect of drugs used in chemotherapy of tumors. The effect of vincristine on these cells has been studied. Vincristine affects cells in S and G2 in such a manner that they are arrested during the next metaphase and subsequently become necrotic. It has no effect on G1 cells.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6639557','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6639557"><span>Atmospheric nuclear weapon test history as characterized by the deposition of sup <span class="hlt">14</span> <span class="hlt">C</span> in human teeth</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Nishizawa, K.; Togari, A.; Matsumoto, S.; Nagatsu, T. )</p> <p>1990-08-01</p> <p>The {sup <span class="hlt">14</span>}<span class="hlt">C</span> concentration in the collagen of human teeth was retrospectively investigated to determine whether its incorporation was related to atmospheric testing of nuclear weapons. Teeth were extracted for dental therapy from July 1987 to February 1988 from patients who were residents in Japan. Tooth collagen was extracted with HCl and converted to amorphous C by heating in a vacuum line. Specimens for {sup <span class="hlt">14</span>}<span class="hlt">C</span> analysis were prepared by mixing the amorphous C with silver powder. The {sup <span class="hlt">14</span>}<span class="hlt">C</span> concentration was measured by mass spectrometer. The {sup <span class="hlt">14</span>}<span class="hlt">C</span> concentration in tooth collagen rapidly increased in 1961 after the bomb tests, peaked around 1967-1968, and then gradually decreased. The collagen of human teeth maintains the {sup <span class="hlt">14</span>}<span class="hlt">C</span> concentration at the age of root completion for life. The results of this study indicate that the history of environmental contamination from atmospheric nuclear weapon's tests has been characterized by deposition of {sup <span class="hlt">14</span>}<span class="hlt">C</span> in the tooth collagen {sup <span class="hlt">14</span>}<span class="hlt">C</span> of human beings.</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/24875877','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24875877"><span>Effects of biochar and the geophagous earthworm Metaphire guillelmi on fate of (<span class="hlt">14</span>)<span class="hlt">C</span>-catechol in an agricultural soil.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shan, Jun; Wang, Yongfeng; Gu, Jianqiang; Zhou, Wenqiang; Ji, Rong; Yan, Xiaoyuan</p> <p>2014-07-01</p> <p>Both biochar and earthworms can exert influence on behaviors of soil-borne monomeric phenols in soil; however, little was known about the combined effects of biochar and earthworm activities on fate of these chemicals in soil. Using (<span class="hlt">14</span>)<span class="hlt">C</span>-catechol as a representative, the mineralization, transformation and residue distribution of phenolic humus monomer in soil amended with different amounts of biochar (0%, 0.05%, 0.5%, and 5%) without/with the geophagous earthworm Metaphire guillelmi were investigated. The results showed biochar at amendment rate <0.5% did not affect (<span class="hlt">14</span>)<span class="hlt">C</span>-catechol mineralization, whereas 5% biochar amendment significantly inhibited the mineralization. Earthworms did not affect the mineralization of (<span class="hlt">14</span>)<span class="hlt">C</span>-catechol in soil amended with <0.5% biochar, but significantly enhanced the mineralization in 5% biochar amended soil when they were present in soil for 9 d. When earthworms were removed from the soil, the mineralization of (<span class="hlt">14</span>)<span class="hlt">C</span>-catechol was significantly lower than that of in earthworm-free soil indicating that (<span class="hlt">14</span>)<span class="hlt">C</span>-catecholic residues were stabilized during their passage through earthworm gut. The assimilation of (<span class="hlt">14</span>)<span class="hlt">C</span> by earthworms was low (1.2%), and was significantly enhanced by biochar amendment, which was attributed to the release of biochar-associated (<span class="hlt">14</span>)<span class="hlt">C</span>-catecholic residues during gut passage of earthworm.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010NIMPB.268.1299S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010NIMPB.268.1299S"><span>Local variations in <span class="hlt">14</span><span class="hlt">C</span> - How is bomb-pulse dating of human tissues and cells affected?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stenström, Kristina; Skog, Göran; Nilsson, Carl Magnus; Hellborg, Ragnar; Svegborn, Sigrid Leide; Georgiadou, Elisavet; Mattsson, Sören</p> <p>2010-04-01</p> <p>Atmospheric nuclear weapons testing in the late 1950s and early 1960s almost doubled the amount of <span class="hlt">14</span><span class="hlt">C</span> in the atmosphere. The resulting <span class="hlt">14</span><span class="hlt">C</span> "bomb-pulse" has been shown to provide useful age information in e.g. forensic and environmental sciences, biology and the geosciences. The technique is also currently being used for retrospective cell dating in man, in order to provide insight into the rate of formation of new cells in the human body. Bomb-pulse dating relies on precise measurements of the declining <span class="hlt">14</span><span class="hlt">C</span> concentration in atmospheric CO 2 collected at clean-air sites. However, it is not always recognized that the calculations can be complicated in some cases by significant local variations in the specific activity of <span class="hlt">14</span><span class="hlt">C</span> in carbon in the air and foodstuff. This paper presents investigations of local <span class="hlt">14</span><span class="hlt">C</span> variations in the vicinities of nuclear installations and laboratories using <span class="hlt">14</span><span class="hlt">C</span>. Levels of <span class="hlt">14</span><span class="hlt">C</span> in workers using this radioisotope are also discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006QSRv...25.1073V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006QSRv...25.1073V"><span>The direct absorption method of <span class="hlt">14</span><span class="hlt">C</span> assay—historical perspective and future potential</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vita-Finzi, Claudio; Leaney, Fred</p> <p>2006-05-01</p> <p>Radiocarbon dating by liquid scintillation counting of 14CO 2 absorbed into an alkaline liquid was first developed for groundwater research. In the 1980s it was applied to molluscs, barnacles, corals and other carbonates, and yielded dependable results within a few hours, with standard errors of ˜10% for ages <14 000 yr, at about 1/200 the price of commercial <span class="hlt">14</span><span class="hlt">C</span> dates. Although its cost has risen fivefold, the first-order approach remains useful in coastal neotectonics, where numerous low-precision determinations are often more useful than a few high-precision dates. Direct absorption (DA) <span class="hlt">14</span><span class="hlt">C</span> dating has now been improved and extended to include wood and charcoal samples, and provides ages in a variety of environments with standard errors similar to those reported by conventional radiometric laboratories and for ages spanning the last 30 000 years. The unit cost for a 'state of the art' DA determination is close to 50% of that by benzene synthesis, but the method is favoured in many hydrological and archaeological applications because it is robust and rapid.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/15013828','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/15013828"><span>Highly Sensitive <span class="hlt">14</span><span class="hlt">C</span> and 3H Quantification of Biochemical Samples Using Accelerator Mass Spectrometry</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ognibene, T J; Vogel, J S</p> <p>2003-10-23</p> <p>Accelerator Mass Spectrometry (AMS) is an isotope ratio mass spectrometer that quantifies low levels of rare isotopes with half-lives between 10 and 10{sup 8} years. Typical sensitivities are 10{sup 6} atoms in a milligram-sized sample. AMS was originally developed for use in the geosciences as a tool to carbon date archaeological artifacts, but has applications in many fields. In the biosciences, the extreme sensitivity of AMS is used to trace nutrients, toxins and therapeutics in humans and animals using less than {micro}g/kg doses containing between 1-100 nCi of {sup <span class="hlt">14</span>}<span class="hlt">C</span>. This sensitivity is used to reduce sample size, reduce chemical exposures to environmental or physiological levels, reduce radiation exposures to subjects, and/or reduce radioactive (and ''mixed'') waste. Compared to decay counting, AMS provides for a much higher measurement throughput for low activity samples. For example, a milligram-sized sample containing 1 dpm of {sup <span class="hlt">14</span>}<span class="hlt">C</span> can be measured to 3% precision in several seconds. That same sample would require approximately 1 week of decay counting to obtain similar precision.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/14690387','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14690387"><span>Distribution of [(<span class="hlt">14</span>)<span class="hlt">C</span>]imidacloprid in sunflowers (Helianthus annuus L.) following seed treatment.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Laurent, François M; Rathahao, Estelle</p> <p>2003-12-31</p> <p>Imidacloprid, a neonicotinic insecticide, has been used as a seed dressing (Gaucho) to protect crops against soil and aerial insects. However, French beekeepers observed abnormal behavior of bees foraging on sunflowers and suspected a link between the imidacloprid seed treatment and the observed bee syndrome. This work studies the distribution of [(<span class="hlt">14</span>)<span class="hlt">C</span>-imidazolidin]imidacloprid (1 mg/seed) in three stages of Gaucho-treated sunflowers grown in an outdoor lysimeter. Plants absorbed <10% of [(<span class="hlt">14</span>)<span class="hlt">C</span>]imidacloprid spiked on seeds, and 75% of that absorbed radioactivity was found in cotyledons. Concentrations in the upper leaves were 20 times lower than in the first leaves. From the extracted radioactivity, imidacloprid accounted for 50% and metabolites for the other 50%. Four major metabolites can be detected, in variable concentrations, among which the hydroxy- and olefin-imidacloprid have toxicities equivalent to that of imidacloprid. In pollen, concentrations of imidacloprid were 13 ng x g(-1). Thus, imidacloprid residues from Gaucho seed treatment contaminated sunflower pollen, involving the translocation of imidacloprid within the plant.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=424073','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=424073"><span>Myocardial metabolism of free fatty acids. Studies with <span class="hlt">14</span><span class="hlt">C</span>-labeled substrates in humans.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wisneski, J A; Gertz, E W; Neese, R A; Mayr, M</p> <p>1987-01-01</p> <p>Free fatty acids are considered to be the major energy source for the myocardium. To investigate the metabolic fate of this substrate in humans, 24 subjects underwent coronary sinus and arterial catheterization. 13 subjects were healthy volunteers and 11 subjects had symptoms of ischemic heart disease. [1-<span class="hlt">14</span><span class="hlt">C</span>]oleate or [1-<span class="hlt">14</span><span class="hlt">C</span>]palmitate bound to albumin was infused at a constant rate of 25 microCi/h. Oxidation was determined by measuring the 14CO2 production. The data demonstrated that a high percentage (84 +/- 17%) of the palmitate and oleate extracted by the myocardium underwent rapid oxidation. A highly significant correlation was present between the arterial level and the amount oxidized (r = 0.82, P less than 0.001 for palmitate; r = 0.77, P less than 0.001 for oleate). The isotope extraction ratio was greater than the chemical extraction ratio. This difference of 6 +/- 2 nmol/ml of blood in the young normal subjects was significantly less than the 12 +/- 4 nmol/ml observed in the ischemic heart disease patients (P less than 0.001). PMID:3805273</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5384402','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5384402"><span>Effect of protein quality on /sup <span class="hlt">14</span>/<span class="hlt">C</span> glucose utilization in isolated rat mammary acini</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Masor, M.L.; Grundleger, M.L.; Jansen, G.R.</p> <p>1986-03-01</p> <p>Poor protein quality has a deleterious effect on lactation in rats. Dams consuming a 13% wheat gluten (WG) diet are unable to maintain litters. Glucose utilization in isolated mammary acini taken from dams at either day 20 of gestation (G20) or day 4 of lactation (L4) was examined in dams consuming 13% WG vs 13% casein-methionine (CM) diets from day of breeding. Dams consuming WG had significantly smaller inguinal-abdominal mammary glands than CM dams at both G20 and L4, and mammary glands of CM but not WG dams were larger at L4 than G20. Both average pup weight and pup daily gain were smaller in WG litters. Basal levels of /sup <span class="hlt">14</span>/<span class="hlt">C</span> glucose oxidation (GO) and /sup <span class="hlt">14</span>/<span class="hlt">C</span> glucose incorporation into lipid (GL) and lactose were examined. A large significant increase in GO and GL occurred in CM dams from G20 to L4 but not in WG dams. Both GO and GL were higher in CM dams on L4 but not at G20. The ratio of GO:GO+GL changed at parturition in CM but not WG dams. The normal changes in glucose utilization by mammary epithelial cells which occur at parturition were impaired by the WG diet.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5325064','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5325064"><span>Factors affecting the uptake of <span class="hlt">14</span><span class="hlt">C</span>-labeled organic chemicals by plants from soil</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Topp, E.; Scheunert, I.; Attar, A.; Korte, F.</p> <p>1986-04-01</p> <p>The uptake of /sup <span class="hlt">14</span>/<span class="hlt">C</span> from various /sup <span class="hlt">14</span>/<span class="hlt">C</span>-labeled organic chemicals from different chemical classes by barley and cress seedlings from soil was studied for 7 days in a closed aerated laboratory apparatus. Uptake by roots and by leaves via the air was determined separately. Although comparative long-term outdoor studies showed that an equilibrium is not reached within a short time period, plant concentration factors after 7 days could be correlated to some physicochemical and structural substance properties. Barley root concentration factors due to root uptake, expressed as concentration in roots divided by concentration in soil, gave a fairly good negative correlation to adsorption coefficients based on soil organic carbon. Barley root concentration factors, expressed as concentration in roots divided by concentration in soil liquid, gave a positive correlation to the n-octanol/water partition coefficients. Uptake of chemicals by barley leaves via air was strongly positively correlated to volatilization of chemicals from soil. Both root and foliar uptake by barley could be correlated well to the molecular weight of 14 chemicals. Uptake of chemicals by cress differed from that by barley, and correlations to physicochemical substance properties mostly were poor.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007QSRv...26..954T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007QSRv...26..954T"><span>AMS <span class="hlt">14</span><span class="hlt">C</span> chronology of the world's southernmost woolly mammoth ( Mammuthus primigenius Blum.)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Takahashi, Keiichi; Wei, Guangbiao; Uno, Hikaru; Yoneda, Minoru; Jin, Changzhu; Sun, Chengkai; Zhang, Sheng; Zhong, Bei</p> <p>2007-04-01</p> <p>The world's definite southernmost woolly mammoth record is a molar from Ji'nan (around 36°N), Shandong Province, China. AMS <span class="hlt">14</span><span class="hlt">C</span> dating of the specimen, gave a conventional <span class="hlt">14</span><span class="hlt">C</span> age of 33,150±250 BP. The period of 40-30 ka BP corresponds to the later phase of the Marine Oxygen Isotope Stage 3 (MIS 3a), recognized as the global interstadial of the last glacial period. However, it is known that the winter monsoon strengthened in Asia during the period 35-33 ka BP, and the age of the woolly mammoth specimen from Ji'nan corresponds to that age. The specimen suggests that this area became cold and dry in 33 ka BP, and grassland or open forest, suitable habitat for woolly mammoths, developed during this short time span. This age is similar to the age of the southernmost woolly mammoth record in Europe, therefore supporting a hypothesis by Porter and An [1995. Correlation between climate events in the North Atlantic and China during the last glaciation. Nature 375, 305-308] that an important component of Chinese palaeoclimates may be linked to changes in North Atlantic oceanic conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatSR...638381C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatSR...638381C"><span>Authentication of Chinese vintage liquors using bomb-pulse <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>Cheng, Peng; Zhou, Weijian; Burr, G. S.; Fu, Yunchong; Fan, Yukun; Wu, Shugang</p> <p>2016-12-01</p> <p>The older a bottle of Chinese vintage liquor is, the higher the price it commands. Driven by the potential for higher profits, some newly-founded distilleries openly sell liquor whose storage ages are exaggerated. In China, the market for vintage liquor has become fraught with uncertainty and a pressing need has arisen to establish an effective method to authenticate the age of vintage liquors. A radiocarbon (<span class="hlt">14</span><span class="hlt">C</span>) dating method is described here that can verify cellar-stored years of Chinese liquors distilled within the last fifty years. Two different flavored Chinese liquors produced in “the golden triangular region” in the Upper Yangtze River region in southwest China, with known cellar-stored years, were analyzed to benchmark the technique. Strong flavored liquors are found to be consistent with local atmospheric Δ<span class="hlt">14</span><span class="hlt">C</span> values. A small offset of 2–3 years between predicted vintage years of soy-sauce flavored liquors and strong flavored liquors is found to be associated with the fermentation cycle of certain varieties. The technique can measure cellar-stored years of a wide range of liquors including those with fundamentally different aromas. This demonstrates the strength of our method in identifying suspect Chinese vintage liquors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5138620','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5138620"><span>Authentication of Chinese vintage liquors using bomb-pulse <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>Cheng, Peng; Zhou, Weijian; Burr, G. S.; Fu, Yunchong; Fan, Yukun; Wu, Shugang</p> <p>2016-01-01</p> <p>The older a bottle of Chinese vintage liquor is, the higher the price it commands. Driven by the potential for higher profits, some newly-founded distilleries openly sell liquor whose storage ages are exaggerated. In China, the market for vintage liquor has become fraught with uncertainty and a pressing need has arisen to establish an effective method to authenticate the age of vintage liquors. A radiocarbon (<span class="hlt">14</span><span class="hlt">C</span>) dating method is described here that can verify cellar-stored years of Chinese liquors distilled within the last fifty years. Two different flavored Chinese liquors produced in “the golden triangular region” in the Upper Yangtze River region in southwest China, with known cellar-stored years, were analyzed to benchmark the technique. Strong flavored liquors are found to be consistent with local atmospheric Δ<span class="hlt">14</span><span class="hlt">C</span> values. A small offset of 2–3 years between predicted vintage years of soy-sauce flavored liquors and strong flavored liquors is found to be associated with the fermentation cycle of certain varieties. The technique can measure cellar-stored years of a wide range of liquors including those with fundamentally different aromas. This demonstrates the strength of our method in identifying suspect Chinese vintage liquors. PMID:27922117</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5092697','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5092697"><span>Photoperiodic control of soybean /sup <span class="hlt">14</span>/<span class="hlt">C</span>-assimilate partitioning during the seed filling period</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Morandi, E.N.</p> <p>1986-04-01</p> <p>Photoperiod not only controls the timing of flowering, but also affects later stages of seed development. To study its effect on assimilate partitioning, soybean plants were kept in short days (SD) or night interrupted (NI) during seed filling. The source-sink ratio was fixed to one leaflet-one pod per node. The node was girdle-isolated and its leaflet was pulse labelled with /sup 14/CO/sub 2/. SD plants partitioned more /sup <span class="hlt">14</span>/<span class="hlt">C</span> into seeds, while NI plants showed higher proportions in the petiole, stem and carpel. Seed growth rate and final seed dry weight were increased by 40% in SD. The sugar/starch ratio was increased in cotyledons and decreased in leaves of SD plants. In contrast, NI plants showed more /sup <span class="hlt">14</span>/<span class="hlt">C</span> incorporation into proteins. No changes were detected in carbon exchange ratio, dark respiration and total node dry weight. Thus, photoperiodic induced changes in carbohydrate and protein partitioning occurred without changes in the overall assimilatory process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/7007912','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/7007912"><span>Inhibition of loading of sup <span class="hlt">14</span> <span class="hlt">C</span> assimilate by p-chloromercuribenzenesulfonic acid. [Vicia faba L</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bourquin, S.; Bonnemain, J.L.; Delrot, S. )</p> <p>1990-01-01</p> <p>The apoplast of mature leaves excised from broadbean (Vicia faba L.) plants was infiltrated with 2 millimolar p-chloromercuribenzenesulfonic acid (PCMBS) via the transpiration stream, and the ability of the tissues to take up sugars was tested. An infiltration time of 75 minutes was sufficient of obtain a maximal (75%) inhibition of exogenous ({sup <span class="hlt">14</span>}<span class="hlt">C</span>)sucrose (1 millimolar) uptake. This infiltration affected neither CO{sub 2} assimilation nor the transmembrane potential difference of leaf cells but strongly inhibited phloem loading of endogenous ({sup <span class="hlt">14</span>}<span class="hlt">C</span>) assimilates. The study of the symplastic relations between the different cell types of the mature leaf showed that the density of the plasmodesmata is generally very low in comparison with other species investigated so far, particularly when considering the mesophyll/bundle sheath and the bundle sheath/phloem cells connections, as well as the connections of the transfer cell-sieve tube complex with the surrounding cells. These three successive barriers therefore strongly limit the possibilities of symplastic transit of the assimilates to the conducting cells. The comparison of the densities of plasmodesmata in an importing and an exporting leaf suggests that the maturation of the leaf is characterized by a marked symplastic isolation of the phloem, and, within the phloem itself, by the isolation of the conducting complex. As a consequence, these physiological and cytological data demonstrate the apoplastic nature of loading in the mature leaf of Vicia faba, this species undoubtedly presenting a typical model for apoplastic loading.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5925628','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5925628"><span>The disposition of /sup <span class="hlt">14</span>/<span class="hlt">C</span>-trimethyltin in the pregnant rat and fetus</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lipscomb, J.C.; Paule, M.G.; Slikker, W. Jr.</p> <p>1989-03-01</p> <p>Trimethyltin (TMT) is a potent neurotoxicant. For unknown reasons, age at exposure to TMT may dramatically influence the severity of TMT-induced neuropathology. We have demonstrated previously that radiolabel derived from (/sup <span class="hlt">14</span>/<span class="hlt">C</span>)-TMT given to pregnant dams on gestational day (GD) 17 is found in fetal brain and blood. The present study was designed to determine the distribution of radiolabel derived from (<span class="hlt">14</span><span class="hlt">C</span>)-TMT to brain and other tissue in fetuses from dams dosed on either GD 12 or 17 with 7.0 mg/kg TMT chloride. Radioactivity in GD 12 and GD 17 maternal whole blood peaked 1 hour after IP treatment. Whole blood elimination half-lives were 12-15 days. Peak radiolabel concentrations in GD 12 maternal and fetal brain were only 11-30% of those from GD 17 animals, however, peak fetal brain concentrations of radiolabel were not different from their respective maternal brain concentrations. Radiolabel concentrations in liver, kidney, and adrenal of GD 17 dams were higher than those in corresponding GD 12 tissues. Combined urinary and fecal elimination of radiolabel for two weeks after dosing accounted for 31 and 22% of the GD 12 and 17 doses, respectively. It appears that gestational age influences the distribution and elimination of TMT in the rat.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhRvC..95b1303L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhRvC..95b1303L"><span>Selective decay from a candidate of the σ -bond linear-chain state in <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>Li, J.; Ye, Y. L.; Li, Z. H.; Lin, C. J.; Li, Q. T.; Ge, Y. C.; Lou, J. L.; Tian, Z. Y.; Jiang, W.; Yang, Z. H.; Feng, J.; Li, P. J.; Chen, J.; Liu, Q.; Zang, H. L.; Yang, B.; Zhang, Y.; Chen, Z. Q.; Liu, Y.; Sun, X. H.; Ma, J.; Jia, H. M.; Xu, X. X.; Yang, L.; Ma, N. R.; Sun, L. J.</p> <p>2017-02-01</p> <p>A cluster-transfer experiment 9Be(9Be,*14C→α +10Be)4He was carried out using an incident beam energy of 45 MeV. This reaction channel has a large Q value that favors populating the high-lying states in <span class="hlt">14</span><span class="hlt">C</span> and separating various reaction channels. A number of resonant states are reconstructed from the forward-emitting 10Be+α fragments with respect to three sets of well-discriminated final states in 10Be, most of which agree with the previous observations. A state at 22.5(1) MeV in <span class="hlt">14</span><span class="hlt">C</span> is found to decay predominantly into the states around 6 MeV in 10Be daughter nucleus, in line with the unique property of the predicted band head of the σ -bond linear-chain molecular states. A new state at 23.5(1) MeV is identified which decays strongly into the first excited state of 10Be.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19572555','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19572555"><span>Gas chromatograph-combustion system for <span class="hlt">14</span><span class="hlt">C</span>-accelerator mass spectrometry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>McIntyre, Cameron P; Sylva, Sean P; Roberts, Mark L</p> <p>2009-08-01</p> <p>A gas chromatograph-combustion (GC-C) system is described for the introduction of samples as CO(2) gas into a (<span class="hlt">14</span>)<span class="hlt">C</span> accelerator mass spectrometry (AMS) system with a microwave-plasma gas ion source. Samples are injected into a gas chromatograph fitted with a megabore capillary column that uses H(2) as the carrier gas. The gas stream from the outlet of the column is mixed with O(2) and Ar gas and passed through a combustion furnace where the H(2) carrier gas and separated components are quantitatively oxidized to CO(2) and H(2)O. Water vapor is removed using a heated nafion dryer. The Ar carries the CO(2) to the ion source. The system is able to separate and oxidize up to 10 microg of compound and transfer the products from 7.6 mL/min of H(2) carrier gas into 0.2-1.0 mL/min of Ar carrier gas. Chromatographic performance and isotopic fidelity satisfy the requirements of the (<span class="hlt">14</span>)<span class="hlt">C</span>-AMS system for natural abundance measurements. The system is a significant technical advance for GC-AMS and may be capable of providing an increase in sensitivity for other analytical systems such as an isotope-ratio-monitoring GC/MS.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24419777','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24419777"><span>Phyllotactic transitions in the vascular system of Populus deltoides bartr. as determined by (<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>Larson, P R</p> <p>1977-01-01</p> <p>Populus deltoides seedlings progress through 2/5, 3/8, and 5/13 orders of phyllotaxis in attaining Plastochron Index 16 (PI 16). The manner in which the vascular system was reoriented during these phyllotactic transitions was determined by anatomical analysis of serial microsections, whereas the positions of the transitions were determined by (<span class="hlt">14</span>)<span class="hlt">C</span> labeling. The midvein at the tip of leaves representing plants of different PI and leaves of different Leaf Plastochron Index (LPI) was fed (14)CO2 photosynthetically, and primordia LPI 0 through LPI-9 were dissected from the buds and analyzed for (<span class="hlt">14</span>)<span class="hlt">C</span>. By combining the labeling data with the anatomical observations it was possible to reconstruct the vascular system of a plant of PI 16 and to locate the phyllotactic transitions. Both the anatomical and the labeling data showed a high degree of reproducibility among plants suggesting that the phyllotactic pattern to which the vascular system conforms may be programmed in the plant and transmitted acropetally through the developing leaves and procambial strands. The origin of new primordia and the concepts of orthostichy, ontogenetic helix, and Fibonacci sequence are discussed as they apply to the vascular system of P. deltoides.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/2104478','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/2104478"><span>Pharmacokinetics and autoradiography of [3H] or [<span class="hlt">14</span><span class="hlt">C</span>]stepholidine.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Z D; Zhou, C M; Jin, G Z; Zhang, X; Yang, L</p> <p>1990-07-01</p> <p>After iv [3H]stepholidine (SPD) 12 MBq/kg, the concentration-time curve in rats was found to be a two-compartment open model. The distribution phase T1/2 alpha = 3.6 min, the elimination phase T1/2 beta = 168 min. The absorbed radioactivities of [3H] SPD in 15-30 min were 80-87%. The amounts of [3H]SPD bound to plasma protein, liver and kidney homogenates were estimated to be 37, 31, and 30%, respectively. During 3 d after ip [3H]SPD 50 MBq/kg, 56% of the radioactivity was excreted in urine and 5% in feces, thus, it suggested that [3H]SPD was mainly excreted by kidneys. After iv a single dose of [<span class="hlt">14</span><span class="hlt">C</span>]SPD in mice, the whole-body autoradiography showed that [<span class="hlt">14</span><span class="hlt">C</span>]SPD was rapidly distributed among various tissues. High radioactivities were found in kidneys, liver, brain, salivary glands, Harder's glands, heart blood and muscle at 2 min and intensively localized in kidneys and stomach mucosa at 30 min. The radioactivities in these tissues disappeared 4 and 8 h later, while that in intestine could not be detected 24 h later.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27922117','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27922117"><span>Authentication of Chinese vintage liquors using bomb-pulse (<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>Cheng, Peng; Zhou, Weijian; Burr, G S; Fu, Yunchong; Fan, Yukun; Wu, Shugang</p> <p>2016-12-06</p> <p>The older a bottle of Chinese vintage liquor is, the higher the price it commands. Driven by the potential for higher profits, some newly-founded distilleries openly sell liquor whose storage ages are exaggerated. In China, the market for vintage liquor has become fraught with uncertainty and a pressing need has arisen to establish an effective method to authenticate the age of vintage liquors. A radiocarbon ((<span class="hlt">14</span>)<span class="hlt">C</span>) dating method is described here that can verify cellar-stored years of Chinese liquors distilled within the last fifty years. Two different flavored Chinese liquors produced in "the golden triangular region" in the Upper Yangtze River region in southwest China, with known cellar-stored years, were analyzed to benchmark the technique. Strong flavored liquors are found to be consistent with local atmospheric Δ(<span class="hlt">14</span>)<span class="hlt">C</span> values. A small offset of 2-3 years between predicted vintage years of soy-sauce flavored liquors and strong flavored liquors is found to be associated with the fermentation cycle of certain varieties. The technique can measure cellar-stored years of a wide range of liquors including those with fundamentally different aromas. This demonstrates the strength of our method in identifying suspect Chinese vintage liquors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/5982486','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/5982486"><span>Tracing bomb /sup <span class="hlt">14</span>/<span class="hlt">C</span> in the atmosphere 1962--1980</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Nydal, R.; Loevseth, K.</p> <p>1983-04-20</p> <p>When the ever greater series of nuclear tests were exposed to the atmosphere at higher northern latitudes during 1961 and 1962, an attempt was made at this laboratory to trace the distribution of bomb-produced /sup <span class="hlt">14</span>/<span class="hlt">C</span> down to lower latitudes and into the ocean surface. Several ground level stations were established for this purpose in the early 1960's, from Spitsbergen (78 /sup 0/N) to Madagascar (21 /sup 0/S). Measurements were also gradually extended to the ocean surface. The tropospheric measurements which partly have been performed during the last 18 years have proved to be important for testing exchange models for industrial CO/sub 2/ in the atmosphere and more generally for studying the carbon cycle in nature. The present paper includes tables of all the atmospheric /sup <span class="hlt">14</span>/<span class="hlt">C</span> data measured at this laboratory during 18 years. Several graphs are also included and a description of sampling locations and contamination problems. The paper is an answer to those who want to use the data in their own modeling research.</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://adsabs.harvard.edu/abs/1995QuRes..43..249S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995QuRes..43..249S"><span>AMS <span class="hlt">14</span><span class="hlt">C</span> Dates for Extinct Lemurs from Caves in the Ankarana Massif, Northern Madagascar</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Simons, Elwyn L.; Burney, David A.; Chatrath, Prithijit S.; Godfrey, Laurie R.; Jungers, William L.; Rakotosamimanana, Berthe</p> <p>1995-03-01</p> <p>An extensive late Quaternary fauna, including many extinct giant lemurs, has been collected recently in a 110+-km system of caves in the Ankarana Massif of northern Madagascar. AMS <span class="hlt">14</span><span class="hlt">C</span> dates for the acid-insoluble (collagen/gelatin) fraction of bones of the giant lemur Megaladapis (26,150 ± 400 and 12,760 ± 70 yr B.P.) confirm its presence in the area during the late Pleistocene and provide the first Pleistocene <span class="hlt">14</span> <span class="hlt">C</span> ages from bones of the extinct megafauna of the island. The first date from bones of the recently described extinct Babakotia radofilai (4400 ± 60 yr B.P.) shows that it was present in northern Madagascar in mid-Holocene times. A comparative