WorldWideScience

Sample records for c-13 isotopic studies

  1. Yield and enrichment studies of C-13 isotope by multi-photon dissociation of Freon-22 at low temperatures

    Indian Academy of Sciences (India)

    Manoj Kumar; Anant Deshpande; Chintan Gupta; A K Nath

    2003-06-01

    Multi-photon dissociation of Freon-22 (CF2HCl) at low temperatures has been carried out to separate the C-13 isotope using a TEA CO2 laser. Yield and enrichment of C-13 isotope in the product C2F4 are studied at 9(22) laser line as a function of temperature (-50°C to 30°C). It is observed that at a given fluence when the temperature is lowered the yield decreases and the enrichment factor of C-13 increases. Room temperature irradiation of CF2HCl towards the blue edge of C-13 absorption (i.e. at 9(20) laser line) gives low yield of the product (C2F4) at a fluence, which produces the desired enrichment factor of 100. An increase in fluence gives very high yield of C2F4 but the enrichment factor is very low. Irradiating CF2HCl at a temperature of -10°C enhances the enrichment factor to 100 and the yield obtained is comparable to that towards the red edge of C-13 absorption (i.e. at 9(26) laser line). At a given enrichment factor higher enrichment efficiency is achieved when CF2HCl is irradiated at lower temperature.

  2. C-13 isotopic studies of the surface catalysed reactions of methane

    International Nuclear Information System (INIS)

    The ability of methane to methylate aromatic compounds, which are considered to be models for coal, is being studied. Related to this reaction, but at higher temperatures, is the direct formation of benzene from methane in the presence of these catalysts. Controversy exists in the literature on the former reaction, and 13C isotope studies are being used to resolve the question. The interest in this reaction arises because the utilisation of methane, in the form of natural gas, in place of hydrogen for direct coal liquefaction would have major economic advantage. For this reason Isotope studies in this area have contributed significantly to an understanding of the methylation reactions. The paper describes experiments utilising methane13C, which show that methylation of aromatics such as naphthalene by the methane13C is catalysed by microporous, Cu-exchanged SAPO-5, at elevated pressures (6.8 MPa) and temperatures around 400 degree C. The mass spectrometric analysis and n.m.r. study of the isotopic composition of the products of the methylation reaction demonstrate unequivocally that methane provides the additional carbon atom for the methylated products. Thermodynamic calculations predict that the reaction is favourable at high methane pressures under these experimental conditions. The mechanism as suggested by the isotope study is discussed. The catalysts which show activity for the activation of methane for direct methylation of organic compounds, such as naphthalene, toluene, phenol and pyrene, are substituted aluminophosphate molecular sieves, EIAPO-5 (where El=Pb, Cu, Ni and Si) and a number of metal substituted zeolites. Our earlier tritium studies had shown that these catalysts will activate alkanes, at least as far as isotope hydrogen exchange reactions are concerned

  3. Studies of palaeovegetation changes in the Central Amazon by carbon isotopes (12C, 13C, 14C) of soil organic matter

    International Nuclear Information System (INIS)

    The paper presents carbon isotope data δ13C and 14C on soil organic matter collected along an ecosystem transect in southern Amazon state, north-central Amazon region, that includes three distinct vegetation communities: savannah (Campos de Humaita), a savannah-forest transition and forest (Manaus). The study sites are located along road BR 319. Botanical identification and 13C analysis of modern vegetation in the savannah and forest sites indicate that most of the vegetation is C3 plants, although a few C4 plants are present at Campos de Humaita. The 13C and 14C data for soil organic matter in the Humaita region show that significant vegetation changes have occurred in the past, probably associated with climatic changes. During the early Holocene, forest vegetation extended throughout the study region, including areas occupied today by savannah vegetation. Savannah vegetation expanded at least 2 km into the modern forest ecotone during the middle Holocene, suggesting drier conditions. The last approximately 1000 years appear to indicate a recent expansion of forest vegetation, reflecting a return to a more moist climate. The study illustrates that the transition area between forest and savannah vegetation is quite sensitive to climatic changes, and this region should be the focus of more extensive research related to past climate and vegetation dynamics in the Amazon region. (author)

  4. Study of the fusion reaction 13C+13C

    International Nuclear Information System (INIS)

    The fusion reaction 13C+13C has been studied, it must allow, by comparisons with the system 12C+13C already studied to determine how the presence of a supplementary nucleon in the interaction nuclei of the entrance channel affects the energy dependence of the reaction cross section. The reaction 13C+13C has been studied for incident energies E(CM)=3.05 - 6.88 MeV and no resonant structure seems to appear in the coulombian energies. The reaction products are identified by the energy of their gamma transition using a germanium detector situated at zero degree with respect to the incident beam at approximately 1 cm from the target

  5. The dynamic of the contact between Humaita fields and the natural forest of south Amazonas through the isotopic study (12 C, 13 C and 14 C) of the soil organic matter

    International Nuclear Information System (INIS)

    This paper presents isotopic data (12 C, 13 C and 14 C) of five soil profiles from the southern region of State of Amazonas, where is located the Campos de Humaita (savannah) vegetation community, surrounded by the tropical forest. The objective is to supply information about probable palaeoclimatic and palaeovegetation changes occurred in the tropical region for the last 10,000 years. Stable carbon isotopes of the soil organic matter (SOM) were used for the characterization of the expansion/regression process of the ecosystem equilibrium, and the radiocarbon dating of the SOM to establish the chronology. (author). 24 refs., 3 tabs

  6. Natural abundance of N-15 and C-13 in fish tissues and the use of stable isotopes as dietary protein tracers in rainbow trout and gilthead sea bream

    OpenAIRE

    Beltran, M; Fernandez-borras, J.; Medale, Francoise; Perez-sanchez, J.; Kaushik, Sadasivam; Blasco, J.

    2009-01-01

    For developing efficient diets, two sets of experiments examined whether the use and allocation of dietary protein can be traced by labelling with stable isotopes (N-15 and C-13) in two culture fish (Oncorhynchus mykiss and Sparus aurata). In the first experiment, natural abundance and tissue distribution of these isotopes were determined, by measuring the delta C-13 and delta N-15 values by isotopic ratio mass spectrometry, in fingerlings (14-17 g) adapted to diets differing in the percentag...

  7. The Titan 14N/ 15N and 12C/ 13C isotopic ratios in HCN from Cassini/CIRS

    Science.gov (United States)

    Vinatier, Sandrine; Bézard, Bruno; Nixon, Conor A.

    2007-11-01

    We report the detection of H 13CN and HC 15N in mid-infrared spectra recorded by the Composite Infrared Spectrometer (CIRS) aboard Cassini, along with the determination of the 12C/ 13C and 14N/ 15N isotopic ratios. We analyzed two sets of limb spectra recorded near 13-15° S (Tb flyby) and 83° N (T4 flyby) at 0.5 cm -1 resolution. The spectral range 1210-1310 cm -1 was used to retrieve the temperature profile in the range 145-490 km at 13° S and 165-300 km at 83° N. These two temperature profiles were then incorporated in the atmospheric model to retrieve the abundance profile of H 12C 14N, H 13CN and HC 15N from their bands at 713, 706 and 711 cm -1, respectively. The HCN abundance profile was retrieved in the range 90-460 km at 15° S and 165-305 km at 83° N. There is no evidence for vertical variations of the isotopic ratios. Constraining the isotopic abundance profiles to be proportional to the HCN one, we find C12/C13=89-18+22 at 15° S, and 68-12+16 at 83° N, two values that are statistically consistent. A combination of these results yields a 12C/ 13C value equal to 75±12. This global result, as well as the 15° S one, envelop the value in Titan's methane ( 82.3±1) [Niemann, H.B., and 17 colleagues, 2005. Nature 438, 779-784] measured at 10° S and is slightly lower than the terrestrial inorganic standard value (89). The 14N/ 15N isotopic ratio is found equal to 56-13+16 at 15° S and 56-9+10 at 83° N. Combining the two values yields 14N/ 15N = 56 ± 8, which corresponds to an enrichment in 15N of about 4.9 compared with the terrestrial ratio. These results agree with the values obtained from previous ground-based millimeter observations [Hidayat, T., Marten, A., Bézard, B., Gautier, D., Owen, T., Matthews, H.E., Paubert, G., 1997. Icarus 126, 170-182; Marten, A., Hidayat, T., Biraud, Y., Moreno, R., 2002. Icarus 158, 532-544]. The 15N/ 14N ratio found in HCN is ˜3 times higher than in N 2 [Niemann, H.B., and 17 colleagues, 2005. Nature 438, 779

  8. An isotope approach based on C-13 pulse-chase labelling vs. the root trenching method to separate heterotrophic and autotrophic respiration in cultivated peatlands

    Energy Technology Data Exchange (ETDEWEB)

    Biasi, C.; Pitkamaki, A. S.; Tavi, N. M.; Koponen, H. T.; Martikainen, P. J. [Univ.of Eastern Finland, Kuopio (Finland). Dept. of Environmental Science], e-mail: christina.biasi@uef.fi

    2012-11-01

    We tested an isotope method based on C-13 pulse-chase labelling for determining the fractional contribution of soil microbial respiration to overall soil respiration in an organic soil (cutaway peatland, eastern Finland), cultivated with the bioenergy crop, reed canary grass. The plants were exposed to CO{sub 2}-13 for five hours and the label was thereafter determined in CO{sub 2} derived from the soil-root system. A two-pool isotope mixing model was used to separate sources of respiration. The isotopic approach showed that a minimum of 50% of the total CO{sub 2} originated from soil-microbial respiration. Even though the method uses undisturbed soil-plant systems, it has limitations concerning the experimental determination of the true isotopic signal of all components contributing to autotrophic respiration. A trenching experiment which was comparatively conducted resulted in a 71% fractional contribution of soil-microbial respiration. This value was likely overestimated. Further studies are needed to evaluate critically the output from these two partitioning approaches. (orig.)

  9. In vivo determination of very-low-density lipoprotein-apolipoprotein B100 secretion rates in humans with a low dose of L-[1-C-13]valine and isotope ratio mass spectrometry

    NARCIS (Netherlands)

    de Sain-van der Velden, MGM; Rabelink, TJ; Gadellaa, MM; Elzinga, H; Reijngoud, DJ; Kuipers, F; Stellaard, F

    1998-01-01

    The aim of the present study was to determine the rate of very-low-density lipoprotein (VLDL)-apolipoprotein (apo) B100 secretion in humans with a minimized amount of L-[1-C-13]valine infusion in combination with the use of gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) an

  10. 12C/13C and H/D vapor pressure isotope effects of fluoroform: intermolecular interactions in liquid fluoroform

    International Nuclear Information System (INIS)

    A precision cryostat of the Bigeleisen-Brooks-Ribnikar-Ishida (BBIR) type with associated vacuum systems has been constructed and the appropriate temperature/pressure measurement and control systems designed and implemented. Various improvements in the cryostat design were incorporated in order to facilitate the assembly and repair processes. A major design change involved the incorporation of a digital stand alone computer to control cryostat operations. This apparatus was used to measure the 12C/13C and H/D Vapor Pressure Isotope Effects of Fluoroform. Analysis of the measured VPIE results, in light of existing experimental data and theories, has demonstrated the need of a temperature dependent liquid force field, specifically a temperature-dependent interaction force constant between the C-H stretching motion and translational motion in the direction of the figure axis of CHF3. This result is consistent with the observed spectroscopic data and vibrational and configurational models of fluoroform dimers. The intermolecular interaction is believed to be a weak hydrogen-bond in nature

  11. Maximization of yield of C-13 isotope by multiphoton dissociation of Freon-22 using high average power TEA CO2 laser

    Indian Academy of Sciences (India)

    Manoj Kumar; Anant Deshpande; Chintan Gupta; A K Biswas; A K Nath

    2002-12-01

    Selective multi-photon dissociation (MPD) of Freon-22 (CF2HCl) molecules has been carried out using a TEA CO2 laser at various CO2 laser lines (9(20)-9(26)) in order to maximize the yield of C-13 isotope in the product (C2F4) at an enrichment factor of 100. The effects of laser pulse tail due to the presence of N2 in the laser mixture on the enrichment factor and yield of C-13 are investigated. It is found that the addition of a small amount of N2 is possible in the laser mixture without a significant drop in the yield at desired enrichment factor. Addition of a small amount of N2 improves the laser efficiency considerably. At a given pulse energy, a slight change in the near field intensity distribution of a laser severely affects the selectivity of C-13 isotope. The computed far-field intensity distributions of the measured near-field intensities show marked spatial variation in the focal spots that leads to a drop in selectivity. For macroscopic production of C-13 isotope a simple and novel multi-pass cavity has been designed and tested to focus the energy repeatedly keeping the optimum fluence constant at each focal spot.

  12. Study for the charge symmetric systems, 12C+13N and 12C+13C with the orthogonalized coupled-reaction-channel method

    International Nuclear Information System (INIS)

    The charge-symmetric scattering systems, 12C+13N and 12C+13C have been investigated by using the orthogonalized coupled-reaction-channel (OCRC) method with the basis functions of the elastic, inelastic and transfer channels defined by the single-particle states, 1p1/2, 2s1/2, 1d5/2 and 1d3/2 of the valence nucleon in 13N or 13C. The data of the elastic scattering of 13N on 12C measured by Lienard et al. have been explained consistently with the data of the elastic and inelastic scattering of the 12C+13C system. The CRC effects both on the above systems are very strong, although those on the 12C+13N system are fairly weaker than the 12C+13C system. The role of the highly excited single-particle states 1d3/2 is particularly important in the formation of a specific CRC scheme, i.e., the formation of the covalent molecules due to the hybridization caused by the mixing of the different parity single-particle states. The fusion cross sections of the 12C+13C system at energies below the Coulomb barrier are strongly enhanced as a result of the strong CRC effects as compared with those of the 12C+12C system, while in 12C+13N system the enhancement of the sub-barrier fusion has not been observed. The above absorption mechanism for the 12C+13C system explains the lack of the molecular-resonance phenomena observed in the 12C+12C system. We check the effects of the dipole (E1) transition of the valence nucleon in 13N (and also in 13C) due to the core-core Coulomb interaction in the scattering at sub-barrier energies. The effects are not appreciable. (author)

  13. Variablility of stable isotope signatures (delta C-13 and delta N-15) in two spider crab populations (Maja brachydactyla) in Western Europe

    OpenAIRE

    Bodin, N.; Le Loc'H, François; Hily, C.; Caisey, X.; Latrouite, D.; Le Guellec, A. M.

    2007-01-01

    The ontogenic variations of nitrogen and carbon stable isotopic signatures (delta N-15 and delta C-13) were investigated in two spider crab (Maja brachydactyla) populations inhabiting in different biotopes of Western Europe. The Iroise Sea population is localized in Western Brittany and characterized by a seasonal migration occurring on a large bathymetric and habitat gradient while the Seine Bay population, in the Eastern English Channel, remains in a more homogeneous environment during its ...

  14. New guidelines for delta C-13 measurements

    NARCIS (Netherlands)

    Coplen, TB; Brand, WA; Gehre, M; Groning, M; Meijer, HAJ; Toman, B; Verkouteren, RM; Coplen, Tyler B.; Brand, Willi A.; Gröning, Manfred

    2006-01-01

    Consistency of delta C-13 measurements can be improved 39-47% by anchoring the delta C-13 scale with two isotopic reference materials differing substantially in C-13/C-12. It is recommended that delta C-13 values of both organic and inorganic materials be measured and expressed relative to VPDB (Vie

  15. Determination of low isotopic enrichment of L-[1-C-13]valine by gas chromatography combustion isotope ratio mass spectrometry : a robust method for measuring protein fractional synthetic rates in vivo

    NARCIS (Netherlands)

    Reijngoud, DJ; Hellstern, G; Elzinga, H; de Sain-van der Velden, MG; Okken, A; Stellaard, F

    1998-01-01

    A method was developed for measuring protein fractional synthetic rates using the N-methoxycarbonylmethyl ester (MCM) derivative of L-[1-C-13]valine and on-line gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). The derivatization procedure can be performed rapidly and GC sep

  16. C-14 dating and C-13/C-12 isotopic ratio in soils covered by natural vegetation of cerrado-floresta ecosystem at Humaita (AM)/Brazil

    International Nuclear Information System (INIS)

    The most recent evidences show that in the Amazon region significant climatic changes occurred in the Quaternary, with emphasis to the dry periods during the Pleistocene and increased precipitation in the Holocene. In this region are found areas with characteristics of cerrado, surrounded by tropical rain forest. The evaluations of soil, vegetation and climate interactions for the formation of these areas are important. Carbon isotopes (12 C, 13 C, 14 C) have been applied in soil organic matter (SOM) of Humaita region, southern Amazon, to evaluate changes in vegetation communities during the Holocene. Isotopic composition of SOM in the deeper part of the soil profiles, shows that probably in the early Holocene the forest has been in the area today occupied by the cerrado vegetation. The results of SOM in the shallow part of soil profiles characterize perfectly the three types of actual vegetation communities. (author)

  17. Study on Modern Plant C-13 in Western China and Its Significance

    Institute of Scientific and Technical Information of China (English)

    张成君; 陈发虎; 金明

    2003-01-01

    Organic carbon isotopic composition (δ 13 C) is one of the important proxies in paleoenvironment studies. In this paper modern plant δ 13C in the arid areas of China and Tibetan Plateau is studied. It is found that most terrestrial plant species in western China are C3 plants with δ 13C values ranging from -32.6‰ to -23.2‰ and only few species are C4 plants with δ 13C values from - 16.8‰ to - 13.3‰. The δ 13C is closely related to precipitation ( or humidity), i. e., light δ 13C is related to high precipitation (or humid climate), while heavy δ 13C to low precipitation (or dry climate), but there is almost no relation between plant δ 13Cand temperature. Submerged plants have δ 13C values ranging from -22.0‰ to - 12.7‰, like C4 plants, while merged plants have δ 13C values ranging from -28. 1‰ to -24.5‰, like C3plants. It can then be concluded that organic δ 13C variations in terrestrial sediments such as loess and soil in western China can indicate precipitation changes, but those in lake sediments can reflect organic sources and the productivity of different types of aquatic plants.

  18. The circumstellar shell of the post-AGB star HD 56126 the $^{12}C ^{12}C \\/ ^{12}C ^{13}C$isotope ratio and $^{12}C ^{16}O$ column density

    CERN Document Server

    Bakker, E J; Lambert, Eric J. Bakker & David L.

    1998-01-01

    We have made the first detection of circumstellar absorption lines of the 12C13C (Phillips) system 1-0 band and the 12C16O first-overtone 2-0 band in the spectrum of the post-AGB star HD56126 (IRAS07134+1005). The rotational temperatures are lower for molecules with a higher permanent dipole moment. Derived relative column densities ratios are 12C12C/12C13C=36+-13, 12C16O/(12C12C+12C13C)=606+-230, and 12C16O/(12C14N+13C14N)=475+-175. The isotopic exchange reaction for 12C12C is too slow to significantly alter the 12C12C/12C13C ratio and the 12C12C to 12C13C ratio a good measure of half the carbon isotope ratio: 12C/13C=2 X 12C12C/12C13C=72+-26. A fit of the 12C12C excitation model of van Dishoeck & Black (1982) to the relative population distribution of 12C12C yields n sigma / I = 3.3 +- 1.0 X 1e-14. At r=1e16cm this translates in n=1.7e7cm-3 and dM/dt=2.5e-4Msol/year.

  19. The Circumstellar Shell of the Post-Asymptotic Giant Branch Star HD 56126: 12C12C/12C13C Isotope Ratio and 12C16O Column Density

    Science.gov (United States)

    Bakker, Eric J.; Lambert, David L.

    1998-11-01

    We have made the first detection of circumstellar absorption lines of the 12C13C A 1Πu-X 1Σ+g (Phillips) system 1-0 band and the 12C16O X 1Σ+ first-overtone 2-0 band in the spectrum of the post-AGB star HD 56126 (IRAS 07134+1005). All current detections of circumstellar molecular absorption lines toward HD 56126 (12C2, 12C13C, 12C14N, 13C14N, and 12C16O) yield the same heliocentric velocity of VCSE = 77.6 +/- 0.4 km s-1. The 12C2, 12C13C, and 12C16O lines give rotational temperatures and integrated column densities of Trot = 328 +/- 37 K, log Nint = 15.34 +/- 0.10 cm-2, Trot = 256 +/- 30 K, log Nint = 13.79 +/- 0.12 cm-2, and Trot = 51 +/- 37 K, log Nint = 18.12 +/- 0.13 cm-2, respectively. The rotational temperatures are lower for molecules with a higher permanent dipole moment. Derived relative column densities ratios are 12C2/12C13C = 36 +/- 13 and 12C16O/(12C2 + 12C13C) = 606 +/- 230. Combined with data from a previous paper, we find relative column densities of 12C16O/(12C14N + 13C14N) = 475 +/- 175 and 12C14N/13C14N = 38 +/- 2. Under chemical equilibrium conditions, 12C13C is formed twice as easily as 12C2. The isotopic exchange reaction for 12C2 is too slow to significantly alter the 12C2/12C13C ratio, and the 12C2 to 12C13C ratio is a good measure of half the carbon isotope ratio: 12C/13C = 2 × 12C2/12C13C = 72 +/- 26. This is in agreement with our prediction that the isotopic exchange reaction for 12C14N is efficient and our observation in Paper III of 12C14N/13C14N = 38 +/- 2. A fit of the C2 excitation model of van Dishoeck & Black to the relative population distribution of C2 yields nc σ/I = 3.3 +/- 1.0 × 10-14. At r ~= 1016 cm, this translates into nc = 1.7 × 107 cm-3 and Ṁ~=2.5×10-4 M⊙ yr-1.

  20. Gastric emptying of a solid meal starts during meal ingestion : Combined study using C-13-octanoic acid breath test and Doppler ultrasonography - Absence of a lag phase in C-13-octanoic acid breath test

    NARCIS (Netherlands)

    Minderhoud, IM; Mundt, MW; Roelofs, JMM; Samsom, M

    2004-01-01

    Scintigraphy and the C-13-octanoic acid breath test are both applied to assess gastric emptying. Using the C-13-octanoic acid breath test, excretion curves show C-13 excretion immediately after ingestion of a solid egg meal, in contrast with scintigraphy where gastric emptying is observed after a la

  1. Study of α-monosubstituted methyl acetates by C-13 and H-1 Nuclear Magnetic resonance

    International Nuclear Information System (INIS)

    The substituents effects on the methylene and carbonyl carbons chemical shifts of some α-monosubstituted methyl acetates Z-CH2-COOMe(Z=H,Cl,Br,I,OME,SMe,NMe2 and Me) is studied. Some data of Carbon 13 NMr in the light of the substituents empirical and electronic effects are shown. Solvent and concentration effects on the hydrogen-1 chemical shifts of methyl acetate, bromoacetate and Iodoacetate were interpreted in the light of the Cα-C(O)-bond rotational isomerism. (M.J.C.)

  2. The simultaneous biosynthesis and uptake of amino acids by Lactococcus lactis studied by C-13-labeling experiments

    DEFF Research Database (Denmark)

    Jensen, N.B.S.; Christensen, B.; Nielsen, Jette;

    2002-01-01

    Uniformly C-13 labeled glucose was fed to a lactic acid bacterium growing on a defined medium supplemented with all proteinogenic amino acids except glutamate. Aspartate stemming from the protein pool and from the extracellular medium was enriched with C-13 disclosing a substantial de novo biosyn...

  3. Radiation Oxidation Mechanisms in Polyolefins Studied by C-13 Isotopic Labeling

    International Nuclear Information System (INIS)

    Control of oxidative degradation is a critical consideration in most applications involving polymers and radiation. In radiation crosslinking or sterilization, or in the use of polymers in radiation environments (such as nuclear plants), the objective is to minimize degradation as much as possible. In other applications, a controlled, partial degradation is desired to alter processing properties, or to enhance adhesion or solubility. To gain more understanding of the complex processes of radiation oxidation, samples of one important commercial polyolefin, polypropylene, were synthesized in which the three different carbon atoms along the chain were selectively labeled with carbon-13. These samples were subjected to radiation under inert and air atmospheres, and to post-irradiation thermal exposure in air at various temperatures. Analysis of macromolecular radiation-oxidation products was carried out using 13C NMR and FTIR. Time-dependent plots of oxidation products have been obtained from the NMR measurements, including the post-irradiation oxidation of a sample held at room temperature in air that has been monitored for 2 years. Analysis of volatile oxidation products (CO, CO2, and small organic molecules) was accomplished with gas chromatography / mass spectroscopy. The position of the 13C labels in the degradation products, have been traced back to their positions of origin on the macromolecule, providing insights into the chemical reaction mechanisms through which the products were formed. The major solid-phase products include peroxides and alcohols, both formed at tertiary carbon sites along the chain. Other products include methyl ketones, acids, esters, peresters, and hemiketals formed from reaction at the tertiary carbon, together with in-chain ketones and esters from reaction at the secondary chain carbon. No evidence is found of macromolecular products arising from reactions at the methyl side chain. Significant temperature-dependent differences are apparent; for example much higher yields of chain-end methyl ketones, which are the indicator product of chain scission, are generated for both elevated temperature irradiation and for post-irradiation treatment at elevated temperatures. CO and CO2 originate primarily from the secondary chain position, with lesser amounts coming from the methyl side-chain, and a small amount from the tertiary chain carbon. Organic volatiles are remarkably specific in their position of origin within the macromolecule, and their structures reflect the oxidative chain cleavage steps through which they form

  4. Stable isotopes (C-13/C-12 and N-15/N-14) in settling organic matter of the northwestern Mediterranean Sea: biogeochemical implications

    OpenAIRE

    Kerherve, P.; Minagawa, M.; Heussner, S.; Monaco, A.

    2001-01-01

    Dans le cadre de l’expérience ‘High Frequency Flux’ (HFF, programme MATER), des pièges à particules ont été déployés sur la pente continentale au large de Marseille pendant deux mois (16 mars–2 mai 1997) afin de mesurer avec une fréquence d’échantillonnage élevée les flux descendants de particules. Des analyses isotopiques combinées du carbone (13C/12C ou δ13C) et de l’azote (15N/14N ou δ15N) ont été effectuées sur les échantillons comportant suffisamment de matériel. Ces deux isotopes stable...

  5. Study of the production yields of 18F, 11C, 13N and 15O positron emitters from plasma-laser proton sources at ELI-Beamlines for labeling of PET radiopharmaceuticals

    Science.gov (United States)

    Amato, Ernesto; Italiano, Antonio; Margarone, Daniele; Pagano, Benedetta; Baldari, Sergio; Korn, Georg

    2016-03-01

    The development of novel compact PET radionuclide production systems is of great interest to promote the diffusion of PET diagnostics, especially in view of the continuous development of microfluidics labeling approaches. We studied the feasibility to produce clinically-relevant amounts of PET isotopes by means of laser-accelerated proton sources such that expected at the ELI-Beamlines facility. 18F, 11C, 13N and 15O production yields were calculated through the TALYS software, by taking into account the broad proton spectra expected. With the hypothesized proton fluencies, clinically-relevant amounts of radionuclides can be obtained, suitable to prepare single doses of 18F-, 11C- and 13N-labeled radiopharmaceuticals exploiting fast and efficient microfluidic labeling systems.

  6. Topological Constraints on Chain-Folding Structure of Semicrystalline Polymer as Studied by 13C-13C Double Quantum NMR

    Science.gov (United States)

    Hong, Youlee; Miyoshi, Toshikazu

    Chain-folding process is a prominent feature of long polymer chains during crystallization. Over the last half century, much effort has been paid to reveal the chain trajectory. Even though various chain-folding models as well as theories of crystallization at molecule levels have been proposed, they could be not reconciled due to the limited experimental evidences. Recent development of double quantum NMR with selective isotope labeling identified the chain-trajectory of 13C labeled isotactic poly(1-butene). The systematic experiments covered a wide range of parameters, i.e. kinetics, concentration, and molecular weight (Mw) . It was demonstrated that i) adjacent re-entry site was invariant as a function of crystallization temperature (Tc) , concentration, andMw, ii) long-range order of adjacent re-entry sequence is independence of kinetics at a given concentration while it decreased with increasing the polymer concentration at a given Tc due to the increased interruption between the chains, and iii) high Mw chains led to the multilayer folded structures in single crystals, but the melt state induced the identical short adjacent sequences of long and short polymer over a wide range of Tc due to the entanglements. The behaviors indicated that the topological restriction plays significant roles in the chain-folding process rather than the kinetics. The proposed framework to control the chain-folding structure presents a new perspective into the chain organization by either the intra- or inter-chain interaction. National Science Foundation Grants DMR-1105829 and 1408855.

  7. Stable isotopes (delta C-13, delta N-15) and modelling as tools to estimate the trophic ecology of cultivated oysters in two contrasting environments

    OpenAIRE

    Leal, J.; Dubois, Stanislas; Orvain, Francis; Galois, Robert; Blin, J; Ropert, Michel; Bataille, M; OURRY, A.; Lefebvre, S.

    2008-01-01

    Food sources for cultivated marine bivalves generally are not well identified, although they are essential for a better understanding of coastal ecosystems and for the sustainability of shellfish farming activities. In addition to phytoplankton, other organic matter sources (OMS), such as microphytobenthos and detritus (of terrestrial or marine origins), can contribute significantly to the growth of marine bivalves. The aim of this study was to identify the potential food sources and to estim...

  8. Fusion cross section of 12C+13C at sub-barrier energies

    Science.gov (United States)

    Zhang, N. T.; Tang, X. D.; Chen, H.; Chesneanu, D.; Straticiuc, M.; Trache, L.; Burducea, I.; Li, K. A.; Li, Y. J.; Ghita, D. G.; Margineanu, R.; Pantelica, A.; Gomoiu, C.

    2016-02-01

    In the recent work at Notre Dame, correlations between three carbon isotope fusion systems have been studied and it is found that the fusion cross sections of 12C+13Cand 13C+13C provide an upper limit on the fusion cross section of the astrophysically important 12C+12C reaction.The aim of this work is to continue such research by measuring the fusion cross section of the 12C+13C reaction to lower energies. In this experiment, the off-line activity measurement was performed in the ultra-low background laboratory 12C+13C and the fusion cross section for has been determined in the energy range of Ec.m. =2.5-6.8 MeV. Comparison between this work and several models is also presented.

  9. The C-12/C-13 Ratio as a Chemistry Indicator

    Science.gov (United States)

    Wirstroem, Eva; Geppert, Wolf; Persson, Carina; Charnley, Steven

    2011-01-01

    Isotopic ratios of elements are considered powerful tools, e.g. in tracing the origin of solar system body materials, or the degree of nucleosynthesis processing throughout the Galaxy. In interstellar molecules, some isotopic ratios like H/D and C-12/C-13 can also be used as indicators of their chemical origin. Isotope fractionation in gas-phase chemical reactions and gas-dust interaction makes observations of the ratio between C-12 and C-13 isotopologues suitable to distinguish between different formation scenarios. We will present observations of the C-12/C-13 ratio in methanol and formaldehyde towards a sample of embedded, massive young stellar objects. In relation to this we also present results from theoretical modeling showing the usefulness of the C-12/C-13 ratio as a chemistry indicator.

  10. Stable isotope studies

    Energy Technology Data Exchange (ETDEWEB)

    Ishida, T.

    1992-01-01

    The research has been in four general areas: (1) correlation of isotope effects with molecular forces and molecular structures, (2) correlation of zero-point energy and its isotope effects with molecular structure and molecular forces, (3) vapor pressure isotope effects, and (4) fractionation of stable isotopes. 73 refs, 38 figs, 29 tabs.

  11. Stable isotope studies

    International Nuclear Information System (INIS)

    The research has been in four general areas: (1) correlation of isotope effects with molecular forces and molecular structures, (2) correlation of zero-point energy and its isotope effects with molecular structure and molecular forces, (3) vapor pressure isotope effects, and (4) fractionation of stable isotopes. 73 refs, 38 figs, 29 tabs

  12. The relationship between delta C-13 of organic matter and (CO2(aq)) in ocean surface water - Data from the JGOFS site in the northeast Atlantic Ocean and a model. [Joint Global Ocean Flux Study

    Science.gov (United States)

    Rau, G. H.; Takahashi, T.; Des Marais, D. J.; Repeta, D. J.; Martin, J. H.

    1992-01-01

    Consistent with the hypothesis that plankton delta C-14 and (CO2(aq)) are inversely related, increases in both sinking and suspended particulate organic matter (POM) delta C-13 detected by the Joint Global Ocean Flux Study (JGOFS) were highly negatively correlated with mixed-layer (CO2(aq)). A model of plant delta C-13 by Farquhar et al. (1982) is adapted to show that under a constant phytoplankton demand for CO2 an inverse nonlinear suspended POM delta C-13 response to ambient (CO2(aq)) is expected. Differences between predicted and observed suspended POM delta C-13 vs. (CO2(aq)) trends and among observed relationships can be reconciled if biological CO2 demand is allowed to vary.

  13. Spatio-temporal isotopic signatures (delta C-13 and delta N-15) reveal that two sympatric West African mullet species do not feed on the same basal production sources

    OpenAIRE

    Le Loc'H, François; Durand, Jean-Dominique; Diop, K.; Panfili, Jacques

    2015-01-01

    Potential trophic competition between two sympatric mullet species, Mugil cephalus and Mugil curema, was explored in the hypersaline estuary of the Saloum Delta (Senegal) using C-13 and N-15 composition of muscle tissues. Between species, N-15 compositions were similar, suggesting a similar trophic level, while the difference in C-13 compositions indicated that these species did not feed from exactly the same basal production sources or at least not in the same proportions. This result provid...

  14. Isotopic study of Karst water

    International Nuclear Information System (INIS)

    Measurement of the isotopic composition of water formed part of an extended investigation of the water drainage system in the Slovenian Karst. These studies were planned to complement geological and speleological investigations which are already being performed in this area, with the knowledge of the mechanism of changes in the isotopic composition of water in the natural environment on some smaller locations, Planina cave near Postojna where the vertical percolation of meteoric water through the karstified carbonate ceiling was studied and the water catchment areas of some small rivers, Ljubljanica, Rizana and Idrijca. Mass spectrometric investigations of the isotopic composition of some elements (18O, D, 13C and T) in water and in dissolved carbonates, as well as the isotopic composition of 18O and 13C in cave carbonates were performed. The results allow to conclude that the waters in karst aquifers in spite of producing the homogenisation to a great extent, qualitative determination of the retention time and of the prevailing sources for some springs and surface and underground water flows is nevertheless possible. The isotopic composition of 18O in water and of 18O and 13C in dissolved carbonates depends on climatic conditions and on denudation processes. The investigation of cave carbonates revealed that they have different isotopic compositions of 18O and 13C because of different locations and also different ages

  15. Isotope ratio mass spectrometry in oceanic studies

    International Nuclear Information System (INIS)

    Isotope ratio mass spectrometry (IRMS) is an important and well established method in many scientific fields as analytical chemistry (isotope dilution MS), physical chemistry, nuclear sciences and technology, environmental, agricultural, geological isotope dating, archaeometric, cosmic, bioavailability and nutrition studies, food authentication and adulteration control, elucidation of chemical reaction mechanism, isotope effect studies on chemical reactions and isotope enrichment/separation processes. This paper is aimed to provide a brief summary of IRMS contribution to sea and oceanic studies

  16. Lithium isotopic separation: preliminary studies

    International Nuclear Information System (INIS)

    In order to get the separation of natural isotopes of lithium by electrolytic amalgamation, an electrolytic cell with a confined mercury cathode was used to obtain data for the design of a separation stage. The initial work was followed by the design of a moving mercury cathode electrolytic cell and three experiments with six batches stages were performed for the determination of the elementary separation factor. The value obtained, 1.053, was ill agreement: with the specialized literature. It was verified in all experiments that the lithium - 6 isotope concentrated in the amalgam phase and that the lithium - 7 isotope concentrated in the aqueous phase. A stainless-steel cathode for the decomposition of the lithium amalgam and the selective desamalgamation were also studied. In view of the results obtained, a five stages continuous scheme was proposed. (author)

  17. Radiogenic age and isotopic studies

    International Nuclear Information System (INIS)

    This is one of an annual collection of reports presenting data from the Geochronology Section of the Continental Geoscience Division of the Geological Survey of Canada (GSC). The main purpose of this collection is to make geochronological and other radiogenic isotope data produced by the section available promptly to the geological community. Reports make full presentation of the data, relate these to field settings and make comparatively short interpretations. Other geochronological and isotope data produced in the laboratory but published in outside journals or separate GSC publications are summarized at the end of this report. Report 5 contains 24 papers from most regions of Canada, but particularly from British Columbia. The Geochronology Laboratory has, over the years, provided substantial U-Pb dating for the Cordilleran Division of the Geological Survey of Canada in Vancouver, and the results of a number of these studies are presented this year. A compilation of K-Ar ages is given. (figs., tabs., refs.)

  18. Radiogenic age and isotopic studies

    International Nuclear Information System (INIS)

    This is one of an annual collection of reports presenting data from the Geochronology Section of the Continental Geoscience Division of the Geological Survey of Canada (GSC). The main purpose of this collection is to make geochronological and other radiogenic isotope data produced by the section available promptly to the geological community. Reports make full presentation of the data, relate these to field settings and make comparatively short interpretations. Other geochronological and isotope data produced in the laboratory but published in outside journals or separate GSC publications are summarized at the end of this report. Reports in this issue give U-Pb zircon ages for rocks in Newfoundland, Yukon Territory, Manitoba, Ontario, and the Northwest Territories; present a compilation of K-Ar ages; and discuss Precambrian activity in New Brunswick, the geochronology of rock from the Northwest Territories, and reconnaissance Nd studies of rocks from the Northwest Territories. (figs., tabs., refs.)

  19. A study of 0 transverse polarization transfer in (p, n) reactions from 12C, 13C and 40Ca at 80 and 50 MeV

    International Nuclear Information System (INIS)

    Transverse-polarization-transfer coefficients DNN for the (p, n) reaction at θ=0 have been measured on 12C, 13C and 40Ca targets at Ep=80 MeV and the 12C and 13C targets at Ep=50 MeV. As for the 12C and 13C(p, n) reactions, DNN for the transitions corresponding to the Gamow-Teller type and the Fermi and Gamow-Teller mixed type are compared to distorted-wave Born-approximation calculations. Observed DNN values are reproduced reasonably well by the calculations employing either the effective interactions M3Y or the M3Ym in which VTτ and Vστ are modified. A value for R2=[σGT(0 )/σF(0 )][B(F)/B(GT)] is deduced by using only the DNN data from the 13C(p, n) reaction, and is roughly consistent with R=[1]/[55]Ep, empirically determined from the cross-section data at 0 . As for the 40Ca(p, n) reaction, the observed value for the giant-dipole-resonance region is DNN=0.23±0.05, indicating that the spinflip and non-spinflip resonances are unresolved. Utilizing information from higher-energy DNN data, the transition-strength ratio f of non-spinflip to spinflip and DNN(SF) pertinent to spinflip transitions have been deduced empirically for the giant-dipole-resonance region. Obtained f and DNN(SF) values are 1.4±0.4 and -0.25±0.10, respectively, and are roughly consistent with the RPA calculations. ((orig.))

  20. Radio-isotopic myocardial study

    International Nuclear Information System (INIS)

    The non invasive study of the myocardium with radio-isotopes is effected either with radio-elements labeling on recently infarcted myocardium, such as PYP Tc 99m, or after I.V. injection of Tl 201 extracted by normal myocardium or after I.V. injection of radio-element which study the myocardial metabolism. The fixation of PYP Tc 99m, bordering that of calcium, appears 24 hours after the onset of the myocardial infarction; then it reduces and disappears a week later; its persistency gives evidence of an evolution to ventricular anevrism. The relatively low sensitivity and specificity of this test should induce to reserve if for precise cases. 201 Tl realizes a map of the myocardial flow because this radio-isotope reflects with damping the variations of coronary flow. The scintigraphy is made either after stress test or after I.V. injection of dipyridamole, and the sensitivity and specificity of the test is better than electrocardiographic exercise stress test. The predictive value of the test for a patient highly depends of the prevalence of the coronary disease for this patient; however the results of Tl scintigraphy are far from an ideal test; quantitative or semi-quantitative analysis of the image compared to the analogical image seems to improve sensitivity for detection of coronary disease. After myocardial infarction, its best use is to detect a left anterior descending stenosis after posterior or inferior infarction. Among the possible radio-elements of myocardial metabolism, scintigraphy with fatty acids opens interesting prospects for the study of the myocardial clearance of the radio-isotope, that reflects the global or regional myocardial metabolism

  1. Stellar Origins of C-13 and N-15-Enriched Presolar SiC Grains

    Science.gov (United States)

    Liu, Nan; Nittler, Larry R.; Alexander, Conel M. O’D.; Wang, Jianhua; Pignatari, Marco; Jose, Jordi; Nguyen, Ann

    2016-01-01

    Extreme excesses of 13 C ( C (12 C/ 13 CSiC 20) in rare presolar SiClar SiC grains have been considered diagnostic of an origin in classical novae [1], though an origin in core-collapse supernovae (CCSNe) has also been proposed [2]. We report multi-element isotopic data for 19 13 C- and 15 N-enriched presolar SiC grains(12 C/13 C<16 and 14 N/ 15 N<150) from an acid resistant residue of the Murchison meteorite. These grains are enriched in 13 C and15 N, but with quite diverse Si isotopic signatures. Four grains with isotopic signatures. Four grains with isotopic signatures. Four grains with isotopic signatures. Four grains with isotopic signatures.

  2. Studies on sulphur isotope variations in nature

    International Nuclear Information System (INIS)

    The variations of sulphur isotopes in natural compounds (and of oxygen isotopes in sulphates) provide a powerful method of investigation in various fields of earth sciences such as hydrology, geochemistry, geothermal exploration, volcanology, oceanography, sedimentology, ore formation, environmental sciences and others, although probably the method is not equally mature in all these fields, because of the inherent complexity and, sometimes, insufficient basic data. To review the current situation, and to identify trends of research and application of sulphur isotopes, the International Atomic Energy Agency held an Advisory Group Meeting on the Hydrology and Geochemistry of Sulphur Isotopes, which took place in Vienna at the IAEA Headquarters from 17 to 20 June 1985. Most of the papers presented at the meeting are included in this publication under the following titles: Isotopic composition of dissolved oceanic sulphate; Sulphur isotopes in the water of Lake Neusiedl, Austria; Relationships between the sulphur and oxygen isotope composition of dissolved sulphate; Sulphur and sulphate-oxygen isotopes in New Zealand geothermal systems and volcanic discharges; Isotopic composition and origin of sulphur compounds in groundwaters and brines in the Po Valley (northern Italy); Two case studies on the origin of aqueous sulphate in deep crystalline rocks; Sulphur and oxygen isotopic compositions of groundwater - and sabkha - sulphate in the Middle East; Radiolytic oxidation of sulphides and geochemical behaviour of sulphur isotopes in uranium deposits; On bias in 34S/32S data obtained using SO2 gas in mass spectrometry; Sulphur isotope analyses of trace sulphide and sulphate in various materials using Kiba reagent. Refs, figs and tabs

  3. Radiogenic age and isotopic studies

    International Nuclear Information System (INIS)

    This is one of an annual collection of reports presenting data from the Geochronology Section of the Continental Geoscience Division of the Geological Survey of Canada (GSC). The main purpose of this collection is to make geochronological and other radiogenic isotope data produced by the section available promptly to the geological community. Reports make full presentation of the data, relate these to field settings and make comparatively short interpretations. Other geochronological and isotope data produced in the laboratory but published in outside journals or separate GSC publications are summarized at the end of this report. Reports in this issue cover methods for Rb-Sr and Sm-Nd isotopic analyses; 40Ar-39Ar ages for the New Quebec Crater and for basaltic rocks; U-Pb ages for a differentiated mafic sill in the Ogilvie Mountains, plutonic rocks in the Contwoyto-Nose Lakes are, zircons from the Anton Complex, the Clinton-Colden gabbro-anorthosite intrusion, the Himag plutonic suite, the Campbell granite, the Central Gneiss Belt, Silurian granites, a metarhyolite, plagiogranite and gabbro, and the Wage shear zone; Rb-Sr ages for granitic rocks; K-Ar and Rb-Sr geochronology of granites; a compilation of K-Ar ages; ages of archean and proterozoic mylonites and pre-Misi granitoid domes; and reconnaissance geochronology of Baffin Island

  4. Metabolic studies in man using stable isotopes

    International Nuclear Information System (INIS)

    In this project, stable isotope compounds and stable isotope pharmaceuticals were used (with emphasis on the application of 15N) to study several aspects of nitrogen metabolism in man. Of the many methods available, the 15N stable isotope tracer technique holds a special position because the methodology for application and nitrogen isotope analysis is proven and reliable. Valid routine methods using 15N analysis by emission spectrometry have been demonstrated. Several methods for the preparation of biological material were developed during our participation in the Coordinated Research Programme. In these studies, direct procedures (i.e. use of diluted urine as a samples without chemical preparation) or rapid isolation methods were favoured. Within the scope of the Analytical Quality Control Service (AQCS) enriched stable isotope reference materials for medical and biological studies were prepared and are now available through the International Atomic Energy Agency. The materials are of special importance as the increasing application of stable isotopes as tracers in medical, biological and agricultural studies has focused interest on reliable measurements of biological material of different origin. 24 refs

  5. A C13-norisoprenoid gentiobioside from quince fruit.

    Science.gov (United States)

    Winterhalter, P; Harmsen, S; Trani, F

    1991-01-01

    The beta-D-gentiobioside [beta-D-glucopyranosyl(1----6)-beta-D-glucopyranoside] of 3-hydroxy-beta-ionol has been isolated and characterized in quince (Cydonia oblonga) fruit through spectral and chemical studies. Model experiments carried out with this new natural compound revealed its important role as precursor of a number of C13-norisoprenoid flavour compounds of quince essential oil. PMID:1367795

  6. Study of neutron-deficient Sn isotopes

    International Nuclear Information System (INIS)

    The formation of neutron deficient nuclei by heavy ion reactions is investigated. The experimental technique is presented, and the results obtained concerning Sn et In isotopes reported: first excited states of 106Sn, high spin states in 107Sn and 107In; Yrast levels of 106Sn, 107Sn, 108Sn; study of neutron deficient Sn and In isotopes formed by the desintegration of the compound nucleus 112Xe. All these results are discussed

  7. Enrichment of Gadolinium isotope: column chromatography study

    International Nuclear Information System (INIS)

    Naturally occurring Gadolinium consists of 7 stable isotopes. 152Gd, 154 Gd, 155Gd 156Gd, 157Gd, 158Gd and 160Gd of which abundance ratios are 0.20, 2.18, 14.80, 20.47, 15.65, 24.84 and 21.86% respectively. Gd has the highest cross section for the capture of thermal neutrons of any element due to the high cross section of 157Gd (254,000 barn) and 155Gd (60,900 barn). All the remaining isotopes are having lower values (1.4-735 barn). Gd is used as a burnable poison in nuclear fuel, but the use of 155/157Gd would create an even more effective burnable poison. Gd isotope separation by displacement chromatography was performed in cation exchange resin. Column experiments were performed using 3 jacketed glass columns in series (10 mm dia and 1m length) packed with Dowex 50X8 of bed height of 90 cm. Initially the bed was converted to Cu2+ form. Then 50 cm Gd3+ band was formed using Gd (NO3)3 solution. The band was displaced using (NH4)4-EDTA +NH4NO3 ) solution. The sample was eluted after different migration length of Gd band. The mass spectrometric analysis using TIMS and ICP-MS was performed to measure the enrichment of Gd isotope and the results are found to be encouraging. In the case of natural Gd, the 157/160Gd ratio was found to be 0.7396. The isotopic ratio in the front end was gone down to 0.7077 and in the rear end the value was gone up to 0.7446 which indicates that the front end band is enriched with heavier isotope and rear end is enriched with lighter isotope. Further computational and experimental studies are underway

  8. Isotopic studies in soil and plant nutrition

    International Nuclear Information System (INIS)

    One of the most important peaceful applications of isotopes is in research for the enhancement of our understanding for increased crop production and better management of resources with higher economic efficiency and environmental safety. Nuclear techniques helped in generating useful information on such aspects as use-efficiency of fertilizer nutrients, quantifying their losses from soil and their biological transformations. Such information was, hitherto, obtained indirectly by conventional methods. Radio and stable isotopes have also been successfully employed for getting information in such diverse fields as soil erosion, turnover of soil organic matter, pesticide retention in soil ground water recharge etc. The property of 137Cs adhering tightly to certain exchange surface in soil and its chemically inert nature has made it a useful tool for soil erosion studies. In this paper, applications of isotopes in the research and other such studies as degradation, movement and retention of pesticides, movement of nitrate in soil, biological and ammoniacal nitrogen fixation in soil is discussed

  9. Carbon isotope techniques

    International Nuclear Information System (INIS)

    This book is a hands-on introduction to using carbon isotope tracers in experimental biology and ecology. It is a bench-top reference with protocols for the study of plants, animals, and soils. The 11C, 12C, 13C, and 14C carbon isotopes are considered and standard techniques are described by established authors. The compilation includes the following features: specific, well-established, user-oriented techniques; carbon cycles in plants, animals, soils, air, and water; isotopes in ecological research; examples and sample calculations

  10. The 12C/13C ratio in stellar atmospheres. VI. Five luminous cool stars

    International Nuclear Information System (INIS)

    The isotopic abundance ratio, 12C/13C, is derived from the CO vibration rotation lines at 1.6 and 2.3 μ for five cool luminous stars by a simple curve-of-growth technique. A new analysis of CN lines at 8000 A is also described for α Sco and α Ori. Results derived independently from CO and CN are in agreement. Final results are 12C/13C=7 +- 2(α Ori), 12 +- 3(α Sco), 7 +- 3(β Peg), 25 +- 7(chi Cyg), 17 +- 4(α Her), and 7 +- 1.5(α Boo). The α Boo analysis provides a check on the CO curve-of-growth technique; the 12C/13C ratio from the 2.3 μ CO lines is in good agreement with the previously determined ratio from CN and CH lines

  11. Ab initio studies of the kinetic isotope effect of the CH4 + OH atmospheric reaction

    Science.gov (United States)

    Lasaga, Antonio C.; Gibbs, G. V.

    1991-07-01

    High level ab initio calculations have been carried out on the C-13 - C-12 kinetic isotope effect of the CH4 + OH reaction in the atmosphere. The results agree quite well with both the absolute value of the isotope effect and the temperature dependence of the effect, based on new experimental data. The calculated kinetic isotope effect supports a bigger effect of biomass burning on the methane global budget.

  12. Radiochemical studies of neutron deficient actinide isotopes

    International Nuclear Information System (INIS)

    The production of neutron deficient actinide isotopes in heavy ion reactions was studied using alpha, gamma, x-ray, and spontaneous fission detection systems. A new isotope of berkelium, 242Bk, was produced with a cross-section of approximately 10 μb in reactions of boron on uranium and nitrogen on thorium. It decays by electron capture with a half-life of 7.0 +- 1.3 minutes. The alpha-branching ratio for this isotope is less than 1% and the spontaneous fission ratio is less than 0.03%. Studies of (Heavy Ion, pxn) and (Heavy Ion, αxn) transfer reactions in comparison with (Heavy ion, xn) compound nucleus reactions revealed transfer reaction cross-sections equal to or greater than the compound nucleus yields. The data show that in some cases the yield of an isotope produced via a (H.I.,pxn) or (H.I.,αxn) reaction may be higher than its production via an xn compound nucleus reaction. These results have dire consequences for proponents of the ''Z1 + Z2 = Z/sub 1+2/'' philosophy. It is no longer acceptable to assume that (H.I.,pxn) and (H.I.,αxn) product yields are of no consequence when studying compound nucleus reactions. No evidence for spontaneous fission decay of 228Pu, 230Pu, 232Cm, or 238Cf was observed indicating that strictly empirical extrapolations of spontaneous fission half-life data is inadequate for predictions of half-lives for unknown neutron deficient actinide isotopes

  13. Radiochemical studies of neutron deficient actinide isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Williams, K.E.

    1978-04-01

    The production of neutron deficient actinide isotopes in heavy ion reactions was studied using alpha, gamma, x-ray, and spontaneous fission detection systems. A new isotope of berkelium, /sup 242/Bk, was produced with a cross-section of approximately 10 ..mu..b in reactions of boron on uranium and nitrogen on thorium. It decays by electron capture with a half-life of 7.0 +- 1.3 minutes. The alpha-branching ratio for this isotope is less than 1% and the spontaneous fission ratio is less than 0.03%. Studies of (Heavy Ion, pxn) and (Heavy Ion, ..cap alpha..xn) transfer reactions in comparison with (Heavy ion, xn) compound nucleus reactions revealed transfer reaction cross-sections equal to or greater than the compound nucleus yields. The data show that in some cases the yield of an isotope produced via a (H.I.,pxn) or (H.I.,..cap alpha..xn) reaction may be higher than its production via an xn compound nucleus reaction. These results have dire consequences for proponents of the ''Z/sub 1/ + Z/sub 2/ = Z/sub 1+2/'' philosophy. It is no longer acceptable to assume that (H.I.,pxn) and (H.I.,..cap alpha..xn) product yields are of no consequence when studying compound nucleus reactions. No evidence for spontaneous fission decay of /sup 228/Pu, /sup 230/Pu, /sup 232/Cm, or /sup 238/Cf was observed indicating that strictly empirical extrapolations of spontaneous fission half-life data is inadequate for predictions of half-lives for unknown neutron deficient actinide isotopes.

  14. Particulate organic matter delta C-13 variations across the Drake Passage

    Science.gov (United States)

    Rau, G. H.; Takahashi, T.; Des Marais, D. J.; Sullivan, C. W.

    1991-01-01

    Particulate organic matter (POM) was sampled during two cruise transects across the Drake Passage during March 1986 to investigate the unusual C-13 depletion in high-latitude Southern Ocean plankton. This POM delta C-13 transition from -23.2 o/oo at 53.3 deg S to values as low as -30.3 o/oo at above 62 deg S does not track previously reported abrupt changes in water chemistry and plankton species composition associated with the Polar Front Zone. The north-south isotopic trend is not accompanied by significant changes in POM carbon or nitrogen concentrations, or in POM C/N. Differences in plankton standing crop or biochemistry (e.g. lipid content) do not appear responsible for the isotopic trends observed. The latitudinal change in POM delta C-13 is highly correlated with water temperature and with the calculated concentration of CO2 (aq) at equilibrium with atmospheric CO2. These observations are consistent with the hypothesis that CO2 (aq) significantly influences POM delta C-13 in ocean surface waters.

  15. Human nutritional studies using stable isotopes

    International Nuclear Information System (INIS)

    Methods using stable isotopes in nutritional studies are very useful for assessing the dynamic movement and availability of nutrients. This report introduces the doubly labeled water (DLW) method and the indicator amino acid oxidation (IAAO) method. The DLW method uses H218O and 2H2O to precisely assess the total energy expenditure during free-living conditions. The IAAO method uses L-[1-13C]-phenylalanine to assess the availability of amino acids. The application of stable isotopes in human studies makes it possible to conduct nutritional studies in pregnant and lactating women, young infants, children, and adults of all ages because of its safety and low burden compared with previous methods. (author)

  16. Isotope studies on soil and fertilizer nitrogen

    International Nuclear Information System (INIS)

    Reductions in isotope cost in the 1960s and equipment innovations, have extended compared to 1940, the research of soil and plant scientists so that 15N is now an indispensable tool when working with N. Leadership of FAO/IAEA coordinated research programmes and the Nitrogen Laboratory of the Tennessee Valley Authority helped greatly in bringing about this expanded usage. Recognized isotope effects are of insufficient magnitude to invalidate tracer measurements of field crop uptake in the treatment year if enrichment of 0.3 at.% excess 15N or greater is employed. Thus, use of 15N depleted tracer with potential of 0.366% 15N differential from the standard isotope ratio of N in air is feasible. Its manufacture has allowed further economy in the isotope tag and ultimate treatment of field-scale plots. Interest in Δ15N measurements for predicting the NO-3 contaminant source in surface and ground waters has depreciated. Variations in natural isotope ratio of soil N commonly exceed the differences in Δ15N values of the presumed source materials. 15N provides the only correct measure of fertilizer N utilization efficiency. The field study examples of irrigated maize demonstrate that little or no fertilizer N is likely to escape the root zone where the rate applied does not exceed that required for maximum yield; also, that light and frequent irrigations afford higher yields than heavier, less frequent irrigations. Delaying fertilizer N applications until the crop is well established affords not only higher yields, but greater residual fertilizer N for future crops. Measured effective root activity for absorbing NO-3 has been invaluable in estimating fertilizer requirements of a crop in relation to residual mineral N in soil at planting and projecting the depth at which the NO-3 becomes an environmental hazard. The tag likewise is indispensable in determining symbiotic N fixation

  17. From application of isotope enriched mercury in environmental studies to fractionation of mercury isotopes

    International Nuclear Information System (INIS)

    Full text: This overview on using isotope enriched Hg in environmental studies summarizes results from a whole ecosystem experiment to illustrate aspects of sample preparation and instrumental requirements. Building on our experience in working with isotope-enriched material, our group recently progressed to using multicollector ICPMS for ultra precise isotope ratio determinations, revealing variations in natural Hg isotope ratios. Fractionation is triggered by mass dependent (e.g. reduction and volatilization) and mass independent processes (e.g. photochemical reactions). The presentation will give examples of both mechanisms and discuss Hg isotope fingerprinting as a tool for tracking sources of Hg in the environment. (author)

  18. Environmental isotopes study of precipitation in Syria

    International Nuclear Information System (INIS)

    The rain waters from a network covering 9 meteorological stations distributed in the western part of Syria was studied using environmental isotope techniques. the study shows that the precipitations falling over this part of the country are characterized by a high deuterium excess (d= +19%.) comparing with the global meteoric water (d= +10%.). Meanwhile, the deuterium excess is found to be lower than the estimated one given for the Eastern Mediterranean region (d= +22%.)> The altitude effect is shown up by a progressive depletion of heavy stable isotopes of about 0.23%. and 1.65%. per 100 meters for δ O18 and δ H2, respectively. The spatial distribution pattern of tritium contents shows a gradual build up with the increasing distance from the coast. (author). 5 refs. 6 figs

  19. Preliminary isotope studies in Poyang Lake

    International Nuclear Information System (INIS)

    Poyang Lake is the largest fresh water lake in China, and the largest wetland protection area in Asia. The lake serves as the largest buffer for the Yangtze River as well. In order to make better understanding of the water dynamics, water balance, water chemistry, and the relations between lake, rivers and groundwater, isotope investigation has been carried out systematically for one and a half hydrological years. The paper reports the preliminary results of the study. (author)

  20. C-13 NMR spectra of natural products part 5 - naphthopyrandiones and naphthofurandiones

    International Nuclear Information System (INIS)

    The synthesis of biologically active naphthoquinones using C-13 NMR is studied. The chemical procedure and aspect of carbon chemical shift used to distinguish between ortho and para quinones is described. (M.J.C.)

  1. Isotopic fingerprints in surficial waters : Stable isotope methods applied in hydrogeological studies

    OpenAIRE

    Kortelainen, Nina

    2007-01-01

    The driving force behind this study has been the need to develop and apply methods for investigating the hydrogeochemical processes of significance to water management and artificial groundwater recharge. Isotope partitioning of elements in the course of physicochemical processes produces isotopic variations to their natural reservoirs. Tracer property of the stable isotope abundances of oxygen, hydrogen and carbon has been applied to investigate hydrogeological processes in Finland. The work...

  2. NMR studies of isotopically labeled RNA

    Energy Technology Data Exchange (ETDEWEB)

    Pardi, A. [Univ. of Colorado, Boulder, CO (United States)

    1994-12-01

    In summary, the ability to generate NMR quantities of {sup 15}N and {sup 13}C-labeled RNAs has led to the development of heteronuclear multi-dimensional NMR techniques for simplifying the resonance assignment and structure determination of RNAs. These methods for synthesizing isotopically labeled RNAs are only several years old, and thus there are still relatively few applications of heteronuclear multi-dimensional NMR techniques to RNA. However, given the critical role that RNAs play in cellular function, one can expect to see an increasing number of NMR structural studies of biologically active RNAs.

  3. Isotope pattern deconvolution as rising tool for isotope tracer studies in environmental research

    Science.gov (United States)

    Irrgeher, Johanna; Zitek, Andreas; Prohaska, Thomas

    2014-05-01

    During the last decade stable isotope tracers have emerged as versatile tool in ecological research. Besides 'intrinsic' isotope tracers caused by the natural variation of isotopes, the intentional introduction of 'extrinsic' enriched stable isotope tracers into biological systems has gained significant interest. Hereby the induced change in the natural isotopic composition of an element allows amongst others for studying the fate and fluxes of metals, trace elements and species in organisms or provides an intrinsic marker or tag of particular biological samples. Due to the shoreless potential of this methodology, the number of publications dealing with applications of isotope (double) spikes as tracers to address research questions in 'real world systems' is constantly increasing. However, some isotope systems like the natural Sr isotopic system, although potentially very powerful for this type of application, are still rarely used, mainly because their adequate measurement/determination poses major analytical challenges; as e.g. Sr is available in significant amounts in natural samples. In addition, biological systems underlie complex processes such as metabolism, adsorption/desorption or oxidation/reduction. As a consequence, classic evaluation approaches such as the isotope dilution mass spectrometry equation are often not applicable because of the unknown amount of tracer finally present in the sample. Isotope pattern deconvolution (IPD), based on multiple linear regression, serves as simplified alternative data processing strategy to double spike isotope dilution calculations. The outstanding advantage of this mathematical tool lies in the possibility of deconvolving the isotope pattern in a spiked sample without knowing the quantities of enriched isotope tracer being incorporated into the natural sample matrix as well as the degree of impurities and species-interconversion (e.g. from sample preparation). Here, the potential of IPD for environmental tracer

  4. Applications of isotope differentiation for metabolic studies with di-(2-ethylhexyl) phthalate

    International Nuclear Information System (INIS)

    The pervasiveness of the plasticizer di-(2-ethylhexyl) phthalate (DEHP) in the environment and especially in the laboratory results in a background that may cause severe interference with analytical studies. Animal-to-animal variability in the distribution of DEHP metabolites in excreta normally makes it necessary to use large groups of animals when different treatments are compared. Finally, radioactive tracers are usually considered undesirable for metabolic studies involving human subjects. All of these problems can be overcome through the use of multiple isotopic labels, especially 12C/13C/14C. Examples are given involving rats and monkeys, and applicability to humans is discussed. The principles involved are not limited to any particular class of test compounds. In rats, the competing pathways for metabolism of phthalate esters produce a different distribution of metabolites from a small intravenous dose of DEHP than from a large oral dose

  5. Ethane's 12C/13C Ratio in Titan: Implications for Methane Replenishment

    Science.gov (United States)

    Jennings, Donald E.; Nixon, C. A.; Romani, P. N.; Bjoraker, G. L.; Sada, P. V.; Lunsford, A. W.; Boyle, R. J.; Hesman, B. E.; McCabe, G. H.

    2009-01-01

    As the .main destination of carbon in the destruction of methane in the atmosphere of Titan, ethane provides information about the carbon isotopic composition of the reservoir from which methane is replenished. If the amount of methane entering the atmosphere is presently equal to the amount converted to ethane, the 12C/13C ratio in ethane should be close to the ratio in the reservoir. We have measured the 12C/13C ratio in ethane both with Cassini CIRS(exp 1) and from the ground and find that it is very close to the telluric standard and outer planet values (89), consistent with a primordial origin for the methane reservoir. The lower 12C/13C ratio measured for methane by Huygens GCMS (82.3) can be explained if the conversion of CH4 to CH3 (and C2H6) favors 12C over 13C with a carbon kinetic isotope effect of 1.08. The time required for the atmospheric methane to reach equilibrium, i.e., for replenishment to equal destruction, is approximately 5 methane atmospheric lifetimes.

  6. Isotope hydrology studies of water resources (Tabas area case study)

    International Nuclear Information System (INIS)

    Tabas Town with a surface area of 55,000 km2 is located in north-east of Yazd City in the east of Iran. It is situated in western slopes of eastern heights of the country, on sediments of fourth era, on the edge of Kavir-e-Namak Desert. The study area falls between 56 deg. to 57 deg. 45' eastern longitudes and 32 deg. 15' to 34 deg. 15' northern latitude. The project aims at providing water for washing carbons, cooling systems and potable water purposes in Tabas carbon power plant. Investigating the origin, age and nature of different water resources and relationships between these resources is the main objective of conducting isotope studies in Tabas area. This will help in providing required water in the area. Determining under-investigation water resources, taking samples and isotope and chemical analysis of samples form methodology of present research. 18O and D stable environmental isotopes and T and 14C radioisotopes as well as results of chemical analysis of samples taken from different water resources have been used in studies. First stage of studies consists of sample-taking from 34 springs, 13 wells and 8 Qanats during both wet and dry seasons. Isotope and chemical analyses have been also made on taken samples. Main results achieved could be summarized as: 1) recharge centers of water resources are found in some parts beyond the study area; 2) regarding stable environmental isotopes tests results, recharge centers of water resources within the study area are mainly located in heights over 2,700 m; and 3) isotope and chemical tests results indicate a slight effect of evaporation on increasing salts contents of water resources in the area, whereas the increasing rate mainly depend on the rate of dissolving salts in evaporative and desert rocks on the course of groundwater flows. (author)

  7. Study of groundwater recharge in Rechna Doab using isotope techniques

    International Nuclear Information System (INIS)

    Isotopic studies were performed in the Rechna Doab area to understand the recharge mechanism, investigate the relative contributions from various sources such as rainfall, rivers and canal system and to estimate the turn over times and replenishment rate of groundwater. The isotopic data suggest that the groundwater in the project area can be divided into different zones each having its own characteristic isotopic composition. The enriched isotopic values show rain recharge and depleted isotopic values are associated with river/canal system while the intermediate isotopic values show a mixing of two or more sources of water. The major contribution, however, comes from canal system. The isotopic data suggest that there is no quick movement of groundwater in the area. 18 figs. (author)

  8. Isotopic hydrological studies of the northwest Sahara

    International Nuclear Information System (INIS)

    The study deals mainly with the paleovalley of the Saoura Wadi and includes an examination of the isotopic composition of the aquifers, the precipitations, and the surface system (18O/16O, D/H). The collection of samples from every precipitation at Beni Abbes on the present middle course of the Saoura provides a mean] of determining the 180 content of the heaviest rain storms which could feed the reservoirs, and of assessing the weighted mean isotopic composition of this contribution. The isotopic composition of the Saoura Wadi is studied at different stations along the course of the Wadi. In this way the influence of evaporation on the river waters can be estimated from the south side of the Sahara Atlas mountains where the floods originate to the endorheic basin of the Sebkha-al-Melah, the present limit of the Saoura Wadi where the water evaporates. This is particularly evident in the case of variations in oxygen-18 and deuterium content. On the middle course of the Wadi, the loss through evaporation is partially compensated by a contribution from aquifers whose existence was brought to light by continuous comparative study of the iso- topic composition of the Wadi waters and the Great Western Erg waters. The other regional reservoirs connected with the Saoura valley (those of the Hamada du Guir and of the Ougarta mountains) have also had their 180 content determined. Comparison of the results of these determinations with the present mean value for rainfall provides the basis for a discussion of the problem of how and when they are supplied. The Saoura paleovalley is also a line along which the so-called ''Continental intercalary'' reservoir emerges; this is a water body found at various depths throughout the north Sahara. Samplings made at the available water points in this aquifer, both in the Saoura valley and throughout the western Sahara, can be used for making a specific study of the western part of this reservoir. The data obtained are compared with

  9. Isotopes in soil-plant nutrition studies

    International Nuclear Information System (INIS)

    Radioisotopes have greatly facilitated investigating the characteristics of plant nutrients in the soil, in measuring soil moisture, in studying the uptake of nutrients by plants and in devising efficient methods of fertilizer application, and are now being widely used in soil-plant nutrition research. A recent international symposium on the use of radioisotopes in soil-plant nutrition studies showed the varied ways in which isotopes can contribute to agricultural production by helping to investigate soil characteristics and soil-plant relationships. The symposium, jointly sponsored by the International Atomic Energy Agency and the Food and Agriculture Organization of the United Nations, was held in Bombay from 26 February to 2 March 1962, at the invitation of the Government of India

  10. Transport of C-13-labelled linoleic and C-13-labelled caprylic acid in rat plasma after administration of specific structured triacylglycerols

    DEFF Research Database (Denmark)

    Vistisen, Bodil; Høy, Carl-Erik

    2004-01-01

    transport of dietary C-13-labelled fatty acids in rat plasma to compare the chylomicron fatty acid metabolism after administration of specific structured, long chain and medium chain triacylglycerols. Rats were fed ML*M, M*LM*, L*L*L* or M*M*M* (L=linoleic acid, 18:2n-6, M=caprylic acid, 8:0, * = C-13......The lymphatic transport of structured triacylglycerol consisting of medium and long chain fatty acids in rats has been investigated in several studies, but the following metabolism of the absorbed fatty acids carried in chylomicrons is less elucidated. In the present study we determined the......-labelled fatty acid) by gavage. A maximum transport of 0.5% of the administered C-13-labelled 18:2n-6 was observed in 1mL rat plasma both after administration of L*L*L* and ML*M, while approximately 0.04% of the administered C-13-labelled 8:0 was detected in 1mL plasma following administration of M*M*M* or...

  11. Studies of enzyme mechanism using isotopic probes

    International Nuclear Information System (INIS)

    The isotope partitioning studies of the Ascaris suum NAD-malic enzyme reaction were examined with five transitory complexes including E:NAD, E:NAD:Mg, E:malate, E:Mg:malate, and E:NAD:malate. Three productive complexes, E:NAD, E:NAD:Mg, and E:Mg:malate, were obtained, suggesting a steady-state random mechanism. Data for trapping with E:14C-NAD indicate a rapid equilibrium addition of Mg2+ prior to the addition of malate. Trapping with 14C-malate could only be obtained from the E:Mg2+:14C-malate complex, while no trapping from E:14C-malate was obtained under feasible experimental conditions. The equations for the isotope partitioning studies varying two substrates in the chase solution in an ordered terreactant reaction were derived, allowing a determination of the relative rates of substrate dissociation to the catalytic reaction for each of the productive transitory complexes. NAD and malate are released from the central complex at an identical rate, equal to the catalytic rate. The release of NAD from E:NAD and E:NAD:Mg complexes is 2- to 4-fold and 5- to 9-fold V/sub max//E/sub t/, respectively. The release of malate from the E:Mg:malate complex is 0.1- to 0.3-fold of V/sub max//E/sub t/. The individual rate constants for association and dissociation of the substrates, NAD and malate have been estimated

  12. Studies of enzyme mechanism using isotopic probes

    Energy Technology Data Exchange (ETDEWEB)

    Chen, C.

    1987-01-01

    The isotope partitioning studies of the Ascaris suum NAD-malic enzyme reaction were examined with five transitory complexes including E:NAD, E:NAD:Mg, E:malate, E:Mg:malate, and E:NAD:malate. Three productive complexes, E:NAD, E:NAD:Mg, and E:Mg:malate, were obtained, suggesting a steady-state random mechanism. Data for trapping with E:/sup 14/C-NAD indicate a rapid equilibrium addition of Mg/sup 2 +/ prior to the addition of malate. Trapping with /sup 14/C-malate could only be obtained from the E:Mg/sup 2 +/:/sup 14/C-malate complex, while no trapping from E:/sup 14/C-malate was obtained under feasible experimental conditions. The equations for the isotope partitioning studies varying two substrates in the chase solution in an ordered terreactant reaction were derived, allowing a determination of the relative rates of substrate dissociation to the catalytic reaction for each of the productive transitory complexes. NAD and malate are released from the central complex at an identical rate, equal to the catalytic rate. The release of NAD from E:NAD and E:NAD:Mg complexes is 2- to 4-fold and 5- to 9-fold V/sub max//E/sub t/, respectively. The release of malate from the E:Mg:malate complex is 0.1- to 0.3-fold of V/sub max//E/sub t/. The individual rate constants for association and dissociation of the substrates, NAD and malate have been estimated.

  13. Substitution effect in nuclear magnetic resonance of C-13: α methoxicyclohexanones

    International Nuclear Information System (INIS)

    Eletronic and steric interactions between the carbonyl and methoxyl groups in α-methoxicyclohexanones by H-1 and C-13 nuclear magnetic resonance spectroscopy (n.m.r) is studied. Interpretation of H-1 n.m.r measurements based on the carbonyl group anisotropy is made. The asigment of spectral lines to specific nuclear by Lanthanide Shift Reagent Experiments is confirmed. Interpretation of C-13 n.m.r. spectra with respect to molecular effects and emphirical relationships associated with the substituent was analysed. The C-13 chemical shift asignment by comparison with results of partially (SFORD) and fully decompled spectra and also by relating the measured chemical shift with values cited in the literature for similar compounds are made. A qualitative study using I.R. spectroscopy in attempt to evaluate the predominance of one the conformers of the studied compounds in solutions of n-hexan and chloroform is made. (M.J.C.)

  14. Hydrogeological and isotopic studies for selected springs in Sinai Peninsula

    International Nuclear Information System (INIS)

    This paper deals with the hydrogeology and isotopic composition of water samples collected from selected spring in sinai (e.g. Algudierate, Alqusiema, qidis and Isram) in order to identify their genesis, their interaction with the host rocks and mixing trend. Results of isotopic composition have indicated the similarity in the hydrogeologic situation of Ain qidis and Ain-al-gudierate, while Ain Isram has shown a marked difference in its stable isotope and this could be due to evaporation effect. The isotopic and hydrochemical constituents of the studied springs reflect eater of a meteoric origin with a possible contamination from surficial materials (evaporates) and deeper aquifers. 6 figs., 2 tabs

  15. Hydrological study of the Lima aquifer (Peru) using isotope techniques

    International Nuclear Information System (INIS)

    The Lima aquifer study using hydrochemical and isotopic techniques, has enabled the evaluation of surface water which flows into the basin from the Rivers Rimac, Chillon and Lurin, and to determine various parameters about the functioning of the different aquifers which produce water for human consumption to the city of Lima. The results obtained in this study, show that the isotopic content of the waters that supply the rivers of the mountain range (and contribute to the recharge of the aquifers) varies significantly. This difference in isotopic contents of the rivers is due to differences in altitude of each basin (isotopic gradient of altitude) and permits the localization of areas that contribute to the flow through the three rivers, and from this point to the indirect recharge of the aquifers. The origin of groundwater in the city of Lima is connected to the bank filtration of the rivers Rimac and Chillon. However, the difference in the isotopic content of these two types of water has enabled the identification of seven sectors whose their isotopic characteristics are different, which in turn reflect the different mixtures or different processes that affect groundwater. Comparison of the isotopic content of surface water with groundwater, shows that the surface water is isotopically lighter, which could be explained by the probable presence of seasonal variations in the isotopic content of surface waters as well as the aquifer recharge. (author). 5 refs, 18 figs, 3 tabs

  16. Stable isotope methods in biological and ecological studies of arthropods

    NARCIS (Netherlands)

    Hood-Nowotny, R.C.; Knols, B.G.J.

    2007-01-01

    This is an eclectic review and analysis of contemporary and promising stable isotope methodologies to study the biology and ecology of arthropods. It is augmented with literature from other disciplines, indicative of the potential for knowledge transfer. It is demonstrated that stable isotopes can b

  17. Boron isotope method for study of seawater intrusion

    Institute of Scientific and Technical Information of China (English)

    肖应凯; 尹德忠; 刘卫国; 王庆忠; 魏海珍

    2001-01-01

    A distinct difference in boron isotopes between seawater and terrestrial water is emphasized by δ11B values reported for seawater and groundwater, with an average of 38.8‰ and in the range of -8.9‰ to 9.8‰, respectively. The isotopic composition of boron in groundwater can be used to quantify seawater intrusion and identify intrusion types, e.g. seawater or brine intrusions with different chemical and isotopic characteristics, by using the relation of δ11B and chloride concentration. The feasibility of utilizing boron isotope in groundwater for studying seawater intrusion in Laizhou Bay Region, China, is reported in this study, which shows that boron isotope is a useful and excellent tool for the study of seawater intrusion.

  18. Study of isotopic exchange reactors (1961)

    International Nuclear Information System (INIS)

    A study is made of the general case of the theory of first-order isotopic chemical exchange between a gaseous and a liquid phase in a reactor, starting from fundamental reaction kinetics data, and without making any limiting hypothesis concerning the value of the separation factor. The cases of counter-current reactors and of co-current reactors are considered successively. The general deuterium conservation equation requires the definition of the quotient of the reactor; the performances of this reactor are characterised by its overall efficiency. The idea of the ratio is introduced because it represents a convenient intermediary in the calculations. The search for an additive value for reactors in series leads logically to the defining of an exchange capacity, and a total efficiency, or number of theoretical reactors. This method of expressing the performances of a reactor is more general than the efficiency due to Murphee which only has a physical significance in the particular case of homogeneous liquid reactors. The relationships between these various quantities are established, and the representation due to Mc Cabe and Thiele is generalized. The reactor performances are linked to the first - order reaction kinetics by the transfer number. The relationships are given for a certain number of concrete cases. Finally the application of these calculations is given, together with the approximations necessary in the case where, because of the presence of several components in each phase, the exchange reaction no longer obeys a single kinetic law. (authors)

  19. Hydrochemical and isotope study of Lake Titicaca

    International Nuclear Information System (INIS)

    The chemical and isotopic compositions of Lake Titicaca and its inflow waters (precipitation, tributaries, groundwater) were determined with the aim of establishing the lake chemical and isotope balance. The three main regions of the lake, i.e. the Lago Mayor, the eastern and the western basins of Lago Menor, connected in cascade, show significant chemical and isotopic differences. Chloride and sodium balance indicates that an average of about 92% of the inflow water evaporates, and the remaining 8 % is lost through Rio Desaguadero and infiltration. The balance of each basin is also obtained, including the inter-basin fluxes. The stable isotope balance in not possible because no data are available on the mean atmospheric vapour isotopic composition. However, this was tentatively computed using the fluxes obtained from chemistry. The vapour δ-values are slightly more negative than those of rainfall. Tritium, noble gases and chloro-fluoro-carbons in vertical profiles show that the lake is vertically well mixed and there is no water segregation at depth. (author)

  20. Simulation of interaction of circular clusters C7, C12, C13 with nanographene

    International Nuclear Information System (INIS)

    Interaction of circular carbon clusters C7, C12 and C13 with graphene consisting of 272 atoms has been studied by computer simulation based on the Monte Carlo method. The mutual arrangement of the cluster atoms and graphene and their cohesive energy before and after their interaction have been investigated. (author)

  1. Modification of the Varian XL-100 NMR spectrometer for submilligram natural abundance C-13 analyses

    Science.gov (United States)

    Wilson, D. M.; Olsen, R. W.; Burlingame, A. L.

    1974-01-01

    Quadrature detection modifications and a microcell arrangement are described for the Varian XL-100 NMR spectrometer which routinely improve sensitivity in C-13 Fourier transform sample-limited studies by a factor of 4 to 5. The power requirement of the RF pulse amplifier is relaxed by a factor of 4. Previously attainable resolution is not affected.

  2. Isotopic approach to the provenance study of artifacts

    International Nuclear Information System (INIS)

    Isotopic abundance ratios, which are proved to be generally constant, are known to vary, for certain elements, from one place to another. Light elements, such as hydrogen, lithium, boron, carbon, nitrogen, oxygen and sulfur, show measurable variations of their isotope ratios due to isotopic fractionation which takes place during geochemical or biochemical processes. Isotope ratios of strontium and lead vary due to the decay of long-lived radioactive nuclides 87Rb and 238U-235U-232Th, respectively. Such isotopic anomalies can be applicable to provenance studies of archaeological objects. Thus, 13C/12C, 18O/16O, or 87Sr/86Sr were used to examine the authenticity of Greek marble statues. Also, lead isotope ratios have been used since mid-1960s extensively for provenance studies of glasses and bronzes of different civilizations. As an example, the author presents a series of his own works on lead isotope ratios applied to ancient Japanese bronzes, which are summarized as follows. 1) It was generally observed that lead isotope ratios reflect difference in culture to which bronzes belong. 2) Mirrors in the Western Han period (206 B.C. - A.D.8) are clearly distinguished by lead isotope ratios from those made after the mid-Eastern Han period (ca.A.D.150 - 300). 3) Korean mirrors and weapons excavated from the Yayoi sites contain lead of easily recognizable Mississippi Valley type. 4) Bronze objects made in Japan (imitative Han style mirrors, Dotaku, imitative weapons, arrowheads etc.) in the Yayoi and Kofun periods are classified by lead isotope ratios in the following order: the Korean mirror type to the Western Han mirror type in the Yayoi period and the mid- to post- Han mirror type in the Kofun period. 5) Indigenous Japanese lead seems to have been used after the mid-7th century. (J.P.N.)

  3. Fundamental studies on kinetic isotope effect (KIE) of hydrogen isotope fractionation in natural gas systems

    Science.gov (United States)

    Ni, Y.; Ma, Q.; Ellis, G.S.; Dai, J.; Katz, B.; Zhang, S.; Tang, Y.

    2011-01-01

    Based on quantum chemistry calculations for normal octane homolytic cracking, a kinetic hydrogen isotope fractionation model for methane, ethane, and propane formation is proposed. The activation energy differences between D-substitute and non-substituted methane, ethane, and propane are 318.6, 281.7, and 280.2cal/mol, respectively. In order to determine the effect of the entropy contribution for hydrogen isotopic substitution, a transition state for ethane bond rupture was determined based on density function theory (DFT) calculations. The kinetic isotope effect (KIE) associated with bond rupture in D and H substituted ethane results in a frequency factor ratio of 1.07. Based on the proposed mathematical model of hydrogen isotope fractionation, one can potentially quantify natural gas thermal maturity from measured hydrogen isotope values. Calculated gas maturity values determined by the proposed mathematical model using ??D values in ethane from several basins in the world are in close agreement with similar predictions based on the ??13C composition of ethane. However, gas maturity values calculated from field data of methane and propane using both hydrogen and carbon kinetic isotopic models do not agree as closely. It is possible that ??D values in methane may be affected by microbial mixing and that propane values might be more susceptible to hydrogen exchange with water or to analytical errors. Although the model used in this study is quite preliminary, the results demonstrate that kinetic isotope fractionation effects in hydrogen may be useful in quantitative models of natural gas generation, and that ??D values in ethane might be more suitable for modeling than comparable values in methane and propane. ?? 2011 Elsevier Ltd.

  4. Embryotoxicity of stable isotopes and use of stable isotopes in studies of teratogenetic mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Spielmann, H.; Nau, H.

    1986-07-01

    Experiments on teratogenic effects of stable isotopes from our own and other laboratories are evaluated. In the first series of investigations, the enrichment of the stable isotope /sup 13/C derived from U-/sup 13/C-glucose was studied in mouse embryos at various stages of development, including limb buds in organ culture. Preimplantation mouse embryos incubated in vitro in /sup 13/C-enriched medium for 48 hours showed normal development during subsequent differentiation in vitro and also in vivo after embryo transfer to faster mothers. These embryos were 15% to 20% enriched in /sup 13/C. Administration of U-13-C-glucose to pregnant mice during organogenesis led to an increase of the absolute /sup 13/C content of the embryo for several days after the end of isotope administration, whereas the enrichment in maternal tissue decreased. No alterations of embryonic development were detected due to stable isotope enrichment. Development of cultured mouse limb buds was unaffected by incubation with 82 mol% U-/sup 13/C-glucose as judged from morphologic and biochemical criteria. The second part of the article describes the value of deuterium-labeled drugs as probes into the mechanism of activation of teratogenic metabolites. A comparison of the pharmacokinetics as well as the teratogenicity between cyclophosphamide and some specific deuterium-labeled analogues showed that the isotope effect observed can be related to a particular metabolic pathway crucial for teratogenic activation by this drug.

  5. Preliminary isotope studies of Poyang Lake, China

    International Nuclear Information System (INIS)

    Poyang Lake is the largest fresh water lake in China, and the largest wetland protection area in Asia. The lake serves as the largest buffer for the Yangtze River as well. In order to make better understanding of the water dynamics, water balance, water chemistry, and the relations between lake, rivers and groundwater, isotope investigation has been carried out systematically for one and a half hydrological years. The paper will report the preliminary results from this program. (author)

  6. Preliminary study: isotopic safeguards techniques (IST). LMFBR fuel cycles

    International Nuclear Information System (INIS)

    This memorandum presents the preliminary results of the effort to investigate the applicability of isotope correlation techniques (ICT), formulated for the LWR system, to the LMFBR fuel cycle. The detailed isotopic compositional changes with burnup developed for the CRBR was utilized as the reference case. This differs from the usual LMFBR design studies in that the core uranium is natural uranium rather than depleted. Nevertheless, the general isotopic behavior should not differ significantly and does allow an initial insight into the expected behavior of isotopic correlations for the LMFBR power systems such as: the U.K. PFR and reprocessing plant; the French Phenix and Superphenix; and the US reference conceptual design studies (CDS) of homogeneous and heterogeneous LMFBR systems as they are developed

  7. Molecular modelling guided experimental study for isotopic enrichment of Gadolinium

    International Nuclear Information System (INIS)

    Molecular modelling and experimental studies were performed to predict the feasibility of Gd isotope separation using crown ether grafted resin. BP and B3LYP functional - based DFT calculations foretell the complexation stability order of Gd3+ ion as DCH18C6>B15C5>DB18C6 as observed in the experiment. The calculated isotopic separation factor shows that DB18C6 is the promising candidate. Hence, CMPS grafted DB18C6 resin was chosen for the isotope separation of Gd. The adsorption capacity of the resin for Gd3+ ion was found to be 1mg/g. The separation coefficients (ε ×103) were found to be 6.3, 3.4, 9.7 and 11.1 for the isotopic pair of 155/158, 157/158, 155/160 and 157/160 respectively and shows promise for future study. (author)

  8. Isotope study in geothermal fields in Java Island

    International Nuclear Information System (INIS)

    Study in two geothermal fields, Dieng and Kamojang, in Java island by utilizing isotope technique has been carried out. Isotopic data of wells, springs and other geothermal manifestations providing informations on the recharge area of precipitation contributed to geothermal resources, flow paths and origin of geothermal fluids. The data of oxygen shift has also provided information on the characteristic the fields. (author). 8 refs, 5 figs, 3 tabs

  9. Rapid Stable Isotope Turnover of Larval Fish in a Lake Superior Coastal Wetland: Implications for Diet and Life History Studies

    Science.gov (United States)

    Trophic linkages of larval fish in Lake Superior coastal wetlands, rivers and embayments can be identified using naturally occurring differences in the stable isotope ratios of nitrogen (15N:14N, ?15N) and carbon (13C:12C, ?13C). We sampled pelagic fish larvae weekly during sprin...

  10. Proceedings of the study of environmental change using isotope techniques

    International Nuclear Information System (INIS)

    Global warming is acknowledged as a major crisis facing society today, principally due to anticipated impacts on the environment, and availability and distribution of water resources. Scientific understanding of recent human-induced climate change, as well as evaluation of potential mitigation strategies, is progressively being developed through studies of atmospheric greenhouse gases and modern water energy carbon cycling processes. These efforts have been advanced through study of past global climate changes to understand mechanisms that play a role in determining natural climate fluctuations observed in ice cores, lake and sea sediments, corals, paleo-groundwater, cave deposits, tree rings, and other archives. Predictive models incorporating natural and human-induced climate change processes contribute to a better appreciation for the sensitivity of climate to specific anthropogenic perturbations. Increasingly, isotopes are being integrated in climate change studies. For example, isotope methodologies offer substantial improvements in the ability to label the origin and fate of greenhouse gases, and for studying the water and carbon cycle response to past climate changes, a high priority area for action identified by the Intergovernmental Panel on Climate Change (IPCC). Isotopes are also widely used as diagnostic variables for validation of models aimed at providing a prognosis of future environmental conditions. The International Atomic Energy Agency (IAEA) has long supported research and development of isotope applications for climate studies. The joint IAEA/WMO Global Network for Isotopes in Precipitation managed by the IAEA has for the last four decades provided the basic isotope data necessary for integrating stable oxygen and hydrogen isotopes in climate models. The IAEA has also sponsored co-ordinated research projects on Isotope Variations of Carbon Dioxide and other Trace Gases in the Atmosphere and Isotope-Aided Studies of Atmospheric Carbon Dioxide

  11. Stable isotope studies: Progress report, March 1985--August 1987

    International Nuclear Information System (INIS)

    Studies have been carried out in the following areas: Stable Isotope Fractionation (1) Effects of chemical poisons and surface modifiers on polycrystalline platinum electrode surfaces have been investigated with a goal to develop a new form of heterogeneous catalyst for the hydrogen isotope exchange between dihydrogen and water. (2) A new nitrogen-15 fractionation process has been developed, based on the isotope exchange between liquid N2O3-N2O4 mixture and their vapor phase at a subambient temperature and a raised pressure. (3) A closed chemical recycle process has been developed for use in connection with the refluxer in the Nitrox-type nitrogen-15 plant. Isotope Effects (1) The vapor pressure isotope effect (VPIE) study of liquid fluoromethanes have been completed. (2) The VPIE study of solid and liquid ammonia has been completed. (3) A theoretical foundation of the additivity for the vibrational zero-point energy (ZPE) has been developed. Studies of Liquid Ammonia. With an aim to study intermolecular interaction (and the inversion phenomenon, in particular) in liquid ammonia, and to further investigate various ammonia solutions, a molecular dynamics (MD) study has been initiated. An MD program has been completed, and force field functions have been developed for an ensemble of non-rigid ammonia molecules. 107 refs., 41 figs., 10 tabs

  12. Recoveries of rat lymph FA after administration of specific structured C-13-TAG

    DEFF Research Database (Denmark)

    Vistisen, Bodil; Mu, Huiling; Høy, Carl-Erik

    2003-01-01

    intragastrically administered L*L*L*, M*M*M*, ML*M, and ML*L* (where * = C-13-labeled FA) in rats. Lymph lipids were separated into lipid classes and analyzed by GC combustion isotope ratio MS. The recoveries of lymph TAG 18:2n-6 8 h after administration of L*L*L*, ML*M, and ML*L* were 38.6, 48.4, and 49.......1%, respectively, whereas after 24 h the recoveries were approximately 50% in all experimental groups. The exogenous contribution to lymph TAG 18:2n-6 was approximately 80 and 60% at maximum absorption of the specific structured TAG and L*L*L*, respectively, 3-6 h after administration. The tendency toward more...

  13. Recoveries of rat lymph FA after administration of specific structured C-13-TAG

    DEFF Research Database (Denmark)

    Vistisen, Bodil; Mu, Huiling; Høy, Carl-Erik

    2003-01-01

    intragastrically administered L*L*L*, M*M*M*, ML*M, and ML*L* (where * = C-13-labeled FA) in rats. Lymph lipids were separated into lipid classes and analyzed by GC combustion isotope ratio MS. The recoveries of lymph TAG 18:2n-6 8 h after administration of L*L*L*, ML*M, and ML*L* were 38.6, 48.4, and 49.......1%, respectively, whereas after 24 h the recoveries were approximately 50% in all experimental groups. The exogenous contribution to lymph TAG 18:2n-6 was approximately 80 and 60% at maximum absorption of the specific structured TAG and L*L*L*, respectively, 3-6 h after administration. The tendency toward more...... low stimulation of chylomicron formation. These results demonstrate tendencies toward faster lymphatic recovery of long-chain FA after administration of specific structured TAG compared with long-chain TAG....

  14. Hyperpolarized C-13 MRS Cardiac Metabolism Studies in Pigs

    DEFF Research Database (Denmark)

    Giovannetti, G.; Hartwig, V.; Frijia, F.;

    2012-01-01

    from Ohm’s law, the magnetic field patterns and sample-induced resistances were calculated using a numerical finite-difference time-domain algorithm. After the numerical simulation of both coils, the results are presented as SNR-versus-depth profiles using experimental SNR extracted from the [1-13C...

  15. Carbon Isotope Biogeochemistry of Methane from Anoxic Sediments

    Science.gov (United States)

    Blair, Neal E.

    1993-01-01

    The isotopic composition of naturally occurring methane was used to constrain the tropospheric budget of that radiatively active gas. Numerous studies have shown that the isotopic composition is not constant, even for a specific source, and may vary temporally and spatially. The objective was to develop a process-level model that reproduced the seasonal variations in the C-13/C-12 composition of methane observed at the coastal site, Cape Lookout Bight, NC. Details of the mass balance are provided. Experiments and models designed to determine what factors incluence C-13/C-12 ratio of dissolved CO2 are reported. All the factors described were combined in a model that faithfully reproduces the seasonal C-13/C-12 variations observed at Cape Lookout. The model is described.

  16. Study of He isotopes with AMD + Hartree-Fock

    International Nuclear Information System (INIS)

    We study He isotopes with AMD and AMD + Hartree-Fock, putting stress on the study of 8He. In this paper we represent a single nucleon with the superposition of two Gaussian wave packets. Furthermore we propose a new method to calculate single particle levels, including unoccupied levels. By using the merit of the AMD that it is free from any model assumptions, we study whether deformation and/or clustering exist in any of He isotopes. We investigate the influence of changing the strength of the LS force on He isotopes. We see that the structure of 8He, especially its deformation, is largely dependent on the LS force strength, while that of 6He is not. We study the pairing excitation mechanism by using the wave function projected onto the eigenstate of the angular momentum. (author)

  17. Nitrogen and Oxygen Isotopic Studies of the Marine Nitrogen Cycle

    Science.gov (United States)

    Casciotti, Karen L.

    2016-01-01

    The marine nitrogen cycle is a complex web of microbially mediated reactions that control the inventory, distribution, and speciation of nitrogen in the marine environment. Because nitrogen is a major nutrient that is required by all life, its availability can control biological productivity and ecosystem structure in both surface and deep-ocean communities. Stable isotopes of nitrogen and oxygen in nitrate and nitrite have provided new insights into the rates and distributions of marine nitrogen cycle processes, especially when analyzed in combination with numerical simulations of ocean circulation and biogeochemistry. This review highlights the insights gained from dual-isotope studies applied at regional to global scales and their incorporation into oceanic biogeochemical models. These studies represent significant new advances in the use of isotopic measurements to understand the modern nitrogen cycle, with implications for the study of past ocean productivity, oxygenation, and nutrient status.

  18. Stable Isotopes in Study of Water Balance of Lake Neusiedl, Austria. Investigation of the Reliability of the Stable Isotope Method

    International Nuclear Information System (INIS)

    The isotopic composition of a lake depends on its water balance. Therefore the balance equations of stable isotopes provide information for evaluating the water balance. However, the use of the expensive isotope method is justified only if the errors in the calculated parameters remain within reasonable limits. This problem is discussed and it is shown that the main source of error is that of the isotope content of the moisture evaporating from the lake. Errors in the isotope content of the lake water and its variation with time are also important. Stable isotope measurements have been used to study the water balance of Lake Neusiedl near Vienna. Since 1965 the isotope content of rain, river water, groundwater, and lake water have been determined. To calculate the isotope content of water evaporating from the lake, the isotope content of water vapour above the lake must be known. For this purpose water vapour has been collected continuously with a special sampler since March 1968. This investigation shows that even where all isotope data are determined with good accuracy, it can be difficult to determine the evaporation rate of a lake with an accuracy better than 50%. (author)

  19. Isotope and hydrogeochemical studies of southern Jiangxi geothermal systems, China

    International Nuclear Information System (INIS)

    Southern Jiangxi is a geothermally active region, especially in Hengjing area. According to the work plan of IAEA Regional Collaboration in the Development of Geothermal Energy Resources and Environment Management through Isotope Techniques in East Asia and the Pacific (RAS-8-075), field investigation was carried out in Hengjing, southern Jiangxi Province, to demonstrate the use of isotope and geochemical techniques in low to medium temperature geothermal system. During the field investigation, 19 samples were taken from cold springs, hot springs and surface water in the area to determine their hydrochemical and gas compositions, hydrogen, oxygen, carbon and helium isotopes. The results of the study have shown that the geothermal waters in the studying region are of the same characteristics with the local meteoric water in oxygen and hydrogen isotope composition, indicating the geothermal waters are mainly derived from the local precipitation, while the gas composition and carbon and helium isotopes reveal that some gases in the geothermal waters have mantle origin. (author)

  20. Isotope techniques in the study of environmental change

    International Nuclear Information System (INIS)

    The International Atomic Energy Agency, among its efforts to promote the wider use of isotope techniques in hydrology and related environmental disciplines, organized an International Symposium on Applications of Isotope Techniques in Studying Past and Current Environmental Changes in the Hydrosphere and the Atmosphere, held in 1993 in Vienna. The broad scientific interest and abundant participation in the symposium, as well as the rapid progress seen in this field since then, encouraged the IAEA to organize a second symposium of this kind. It was held from 14 to 18 April 1997 in Vienna and brought together 177 scientists representing 46 Member States, UNESCO, FAO, WMO, the World Climate Research Programme (WCRP) and the International Geosphere-Biosphere Programme (IGBP). The symposium was structured in five sessions of oral presentations, a poster session and a round table discussion that focused on trends and future requirements in isotope hydrology and on applications in climate and environmental research. The major themes covered by the presentations included the use of isotopic tracers in studies of atmospheric and hydrospheric changes and of the human impact on water and the environment. Special emphasis was placed on isotopic archives of climatic and environmental change. Some contributions addressed new technical approaches

  1. Stable isotopes in plant nutrition, soil fertility and environmental studies

    International Nuclear Information System (INIS)

    The individual contributions in these proceedings are indexed separately. Main topics covered include the measurement of biological nitrogen fixation, studies of soil organic matter, investigations of nutrient uptake and use by plants, studies of plant metabolism and new methodologies in the analysis of stable isotopes. Refs, figs and tabs

  2. Rubidium-strontium and uranium-lead isotopic age studies

    International Nuclear Information System (INIS)

    The results of five Rb-Sr isotopic age studies predominantly on whole-rock samples, and six U-Pb studies on zircon monazite concentrates are presented. Descriptions of the geological problems and interpretations of the measured ages are included. Laboratory age determination methods and techniques are described or referenced

  3. Isotope analytics for the evaluation of the feeding influence on the isotope ratio in beef samples

    International Nuclear Information System (INIS)

    Information about the origin of food and associated production systems has a high significance for food control. An extremely promising approach to obtain such information is the determination of isotope ratios of different elements. In this study the correlation of the isotope ratios C-13/C-12, N-15/N-14, Mg-25/Mg-24, and Sr-87/Sr-86 in bovine samples (milk and urine) and the corresponding isotope ratios in feed was investigated. It was shown that in the bovine samples all four isotope ratios correlate with the isotope composition of the feed. The isotope ratios of strontium and magnesium have the advantage that they directly reflect the isotope ratios of the ingested feed since there is no isotope fractionation in the bovine organism which is in contrast to the case of carbon and nitrogen isotope ratios. From the present feeding study it is evident, that a feed change leads to a significant change in the delta C-13 values in milk and urine within 10 days already. For the deltaN-15 values the feed change was only visible in the bovine urine after 49 days. Investigations of cows from two different regions (Berlin/Germany and Goestling/Austria) kept at different feeding regimes revealed no differences in the N-15/N-14 and Mg-26/Mg-24 isotope ratios. The strongest correlation between the isotope ratio of the bovine samples and the kind of ingested feed was observed for the carbon isotope ratio. With this ratio even smallest differences in the feed composition were traceable in the bovine samples. Since different regions usually coincide with different feeding regimes, carbon isotope ratios can be used to distinguish bovine samples from different regions if the delta C-13 values of the ingested feed are different. Furthermore, the determination of strontium isotope ratios revealed significant differences between bovine and feed samples of Berlin and Goestling due to the different geologic realities. Hence the carbon and strontium isotope ratios allow the best

  4. Groundwater surface water interaction study using natural isotopes tracer

    Science.gov (United States)

    Yoon, Yoon Yeol; Kim, Yong Chul; Cho, Soo Young; Lee, Kil Yong

    2015-04-01

    Tritium and stable isotopes are a component of the water molecule, they are the most conservative tracer for groundwater study. And also, radon is natural radioactive nuclide and well dissolved in groundwater. Therefore, these isotopes are used natural tracer for the study of surface water and groundwater interaction of water curtain greenhouse area. The study area used groundwater as a water curtain for warming tool of greenhouse during the winter, and is associated with issues of groundwater shortage while being subject to groundwater-river water interaction. During the winter time, these interactions were studied by using Rn-222, stable isotopes and H-3. These interaction was monitored in multi depth well and linear direction well of groundwater flow. And dam effect was also compared. Samples were collected monthly from October 2013 to April 2014. Radon and tritium were analyzed using Quantulus low background liquid scintillation counter and stable isotopes were analyzed using an IRIS (Isotope Ratio Infrared Spectroscopy ; L2120-i, Picarro). During the winter time, radon concentration was varied from 0.07 Bq/L to 8.9 Bq/L and different interaction was showed between dam. Surface water intrusion was severe at February and restored April when greenhouse warming was ended. The stable isotope results showed different trend with depth and ranged from -9.16 ‰ to -7.24 ‰ for δ 18O value, while the δD value was ranged from -57.86 ‰ to -50.98 ‰. The groundwater age as dated by H-3 was ranged 0.23 Bq/L - 0.59 Bq/L with an average value of 0.37 Bq/L.

  5. Structure of potassium isotopes studied with collinear laser spectroscopy

    CERN Document Server

    AUTHOR|(CDS)2082445

    By exploring the structure of different nuclei, one can learn about the interaction between the nucleons, their building blocks. In this field of research, there is a strong interplay between experiment and theory. In particular, theory has a crucial role in the interpretation of the experimental results, while new experimental results provide testing ground and directions for theorists. In the light- and mid-mass regions of the nuclear chart, the shell model is very successful and widely used for calculations of the ground- as well as excited- states properties. It is based on associated larger energy gaps between single particle energy levels for isotopes with certain proton (Z) and neutron (N) numbers, which are called "magic numbers". It was believed that these numbers (8, 20, 28, ...) are preserved for all nuclei throughout the nuclear chart. However, during the last decades studies of the isotopes with an unbalanced number of protons and neutrons revealed that in these isotopes the shell gaps could chan...

  6. Stable isotope study of Lake Turkana, East Africa

    International Nuclear Information System (INIS)

    The water level of Lake Turkana, East Africa, has fluctuated widely since measurements began in the late 1880s. Lake level has ranged from 15 meters above to 5 meters below the 1968 datum over the last 105 years. This study was initiated to compare the historic record of lake level for Lake Turkana to several records of the isotopic composition of carbonates found in the lake sediments. The ubiquitous presence of inorganic carbonates in Lake Turkana sediments, both spatially and temporally, allows for an evaluation of the use of the isotopic composition of carbonates as a proxy for paleo-lake level. (author)

  7. Relativistic Mean Field Study of the Z = 117 Isotopic Chain

    International Nuclear Information System (INIS)

    The properties of the Z = 117 isotopic chain are studied within the framework of the axially deformed relativistic mean field theory (RMFT) in the blocked BCS approximation. The ground-state properties, such as binging energies, deformations as well as the possible α decay energies and lifetimes are calculated with the parameter set of NL-Z2 and compared with results from the finite range droplet model. The analysis by RMFT shows that the isotopes in the range of mass number A = 291 ∼ 300 exhibit higher stability, which suggests that they may be promising nuclei to be hopefully synthesized in the lab among the nuclei Z = 117. (nuclear physics)

  8. Relativistic mean field study of the Z=117 isotopic chain

    International Nuclear Information System (INIS)

    The properties of the Z=117 isotopic chain are studied within the framework of the axially deformed relativistic mean field theory (RMFT) in the blocked BCS approximation. The ground-state properties, such as binding energies, deformations as well as the possible α decay energies and lifetimes are calculated with the parameter set of NL-Z2 and compared with results from the finite range droplet model. The analysis by RMFT shows that the isotopes in the range of mass number A=291-300 exhibit higher stability, which suggests that they may be promising nuclei to be hopefully synthesized in the lab among the nuclei Z-117. (authors)

  9. Applications of C and N stable isotopes to ecological and environmental studies in seagrass ecosystems

    OpenAIRE

    Lepoint, Gilles; Dauby, Patrick; Gobert, Sylvie

    2004-01-01

    Stable isotopes of carbon and nitrogen are increasingly used in marine ecosystems, for ecological and environmental studies. Here, we examine some applications of stable isotopes as ecological integrators or tracers in seagrass ecosystem studies. We focus on both the use of natural isotope abundance as food web integrators or environmental tracers and on the use of stable isotopes as experimental tools. As ecosystem integrators, stable isotopes have helped to elucidate the general structure o...

  10. Laserspectroscopic study of the optical isotope shift and hyperfine structure of stable and radioactive isotopes

    International Nuclear Information System (INIS)

    The isotope shift and hyperfine structure of the CaI resonance line (4s21Ssub(o) - 4s4p 1P1; lambda = 422.7 nm) has been studied in all the calcium isotopes between 40Ca and 48Ca, including the short-lived isotope 47Ca (tsub(1/2) = 4.54 d). Resonance fluorescence was observed in a well-collimated atomic beam of calcium exited by a narrowband tunable continuous wave dye laser. The aim of the experiment was to determine the changes of the mean square radius of the nuclear charge distribution an the nuclear moments of the unstable calcium nuclei. The results are discussed in terms of the information they give about the nuclear structure in calcium, and various theoretical models, including the droplet model, are illustrated. It is shown that to a first approximation the behaviour of the mean square radii is accounted for by quadrupole deformations. The droplet model, which has shown itself capable of describing average nuclear properties in many cases, is not be able to reproduce the mean square radii of the calcium nuclei. (orig.)

  11. The Enriched Background Isotope Study (EBIS)

    Energy Technology Data Exchange (ETDEWEB)

    Hanson, Paul J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Trumbore, Susan [Univ. of California, Irvine, CA (United States); Swanston, Chris [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Torn, Margaret [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Jastrow, Julie [Argonne National Lab. (ANL), Argonne, IL (United States); Parton, William A [Colorado State Univ., Fort Collins, CO (United States); Century Ecosystems, Inc. (United States); Post, Wilfred M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Froberg, Mats J [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Hainsworth, Laura J [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kleber, Markus [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kramer, Christiane [Univ. of California, Irvine, CA (United States); Matamala-Paradeda, Roser [Argonne National Lab. (ANL), Argonne, IL (United States); Garten, Jr, Charles T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2007-02-05

    A unique, large release of radiocarbon occurred near the Oak Ridge Reservation (ORR), Oak Ridge, TN in July/August 1999. Measurements of 14C in tree ring cellulose throughout the ORR area demonstrate that the 1999 release was unprecedented in its uptake by vegetation. We are taking advantage of the whole-ecosystem isotopic label generated by this release to address five outstanding issues in the terrestrial carbon cycle: (1) partitioning of soil respiration between autotrophic and heterotrophic sources, and quantification of that partitioning seasonally and inter-annually, (2) partitioning of heterotrophic respiration sources between above-ground litter decomposition and below-ground root detritus decomposition, (3) identification of pathways leading from leaf and root detritus to long-term stabilization of soil organic matter, including the role of soil fauna, (4) the role of dissolved organic carbon (DOC) transport in distributing carbon within the soil profile, and, (5) the longevity and turnover time of fine roots. The first four issues are being addressed through a reciprocal litter transplant experiment set up at four sites on the ORR encompassing two soil types and two levels of 14C exposure in 1999. The fifth issue, longevity and turnover of fine roots, is being addressed by tracing the radiocarbon label through the fine root pool over time. With a combination of incubation, soil surface chamber and soil CO2 profiles, and continuous measurements of soil temperature and moisture controls, we are tracking changes in soil respiration partitioning over several years. The nature and source of organic matter pools that reside in soils for years to decades are being tracked with differently labeled root and surface litter, and experiments to exclude soil fauna have been initiated to elucidate their role in vertical transport. Periodic sampling of soils and soil solutions and the use of inert tracers, allow us to investigate the chemical nature and form of DOC and

  12. 紫杉醇C13边链的合成%Synthesis of paclitaxel C13 side chain

    Institute of Scientific and Technical Information of China (English)

    赵亚婷; 彭久合; 高瑞昶; 张广明

    2006-01-01

    目的:合成紫杉醇C13边链.方法:反式肉桂酸(1)经单过氧化硫酸氢钾复盐氧化,得到消旋环氧酸(2),化合物2经R-α-苯乙胺拆分、碱化制得钾盐(4),4与叠氮钠的反应产物经酸化得到叠氮酸(5),化合物5用4 mol/L的HCl/MeOH溶液酯化得到叠氮酸甲酯(6),化合物6在含水(15%)四氢呋喃中经Zn/NH4Cl还原、苯甲酰化得到2S-羟基-3S-N-(苯甲酰基)-苯丙酸甲酯(8),化合物8在吡啶中与甲磺酰氯反应即得紫杉醇G13侧链(9).结果:首次以反式肉桂酸(1)为原料制备了紫杉醇C13边链(4S-反式)4,5-二氢-2,4-二苯基-1,3-噁唑-5-甲酸甲酯(9).结论:此方法原料易得,反应条件温和并且成本低,易于生产化生产.

  13. Isotope-aided studies of residue/biota interactions

    International Nuclear Information System (INIS)

    Current trends in population, demands per capita and land use imply a continuing need and growing use of agrochemicals, especially in developing countries. Studies of the nature, magnitude and persistence of agrochemical residues that find their way into food, the environment and non-target organisms are now an internationally recognized prerequisite for acceptable use. Isotope techniques play a vital role in these studies, as conventional tracers and as monitoring tools for both intended effects and non-intended side effects. They often provide the only effective technique for the detection and characterization of 'bound' residues in soils or plants, which would not be included in conventional chemical analysis based on solvent extraction. Isotope techniques, like all others, have their limitations and certain pitfalls exist. The latter are largely due to an inadequate understanding of the isotope behaviour or biochemistry of the system being studied. It is important to recognize the possibility of effective isotope exchange reactions, whether studying radioisotopically labelled pesticides or 15N-labelled fertilizers. Extensive literature now exists on the fate of agrochemical residues. This indicates that all agrochemical residues tend to undergo chemical modification, biodegradation, dispersion, etc., but some halogenated ring structures appear to be relatively intractable. When considering the significance of known residues it is important to distinguish between acute toxicological effects indicated in the laboratory and the longer term effects on field populations of both 'target' and 'non-target' organisms. The phenomena of pest resistance to pesticides have important implications in this context. (author)

  14. Gas cleaning with hot char beds studied by stable isotopes

    DEFF Research Database (Denmark)

    Egsgaard, Helge; Ahrenfeldt, Jesper; Ambus, Per; Schaumburg, K.; Henriksen, Ulrik Birk

    2014-01-01

    The chemistry taking place in a high temperature char bed used for binding aromatic tar compounds has been studied in detail. 13C labelled tar compounds were used to trace the incorporation into the char bed using isotope ratio mass spectrometry (IRMS) and GC-MS. Furthermore, compounds labelled...

  15. Carbon and nitrogen biogeochemistry in the ocean: A study using stable isotope natural abundance

    Science.gov (United States)

    Rau, G. H.; Desmarais, David J.

    1985-01-01

    Determining the biogeochemical pathways traveled by carbon and nitrogen in the ocean is fundamental to the understanding of how the ocean participates in the cycling of these elements within the biosphere. Because biological production, metabolism, and respiration can significantly alter the natural abundance of C-13 and N-15, these abundances can provide important information about the nature of these biological processes and their variability in the marine environment. The research initially seeks to characterize the spatial and temporal patterns of stable isotope abundances in organic matter, and to relate these abundances to C and N biogeochemical processes within selected areas of the northeastern Pacific Ocean.

  16. Plant root water extraction studies using stable isotopes

    International Nuclear Information System (INIS)

    While stable isotopes of water have been used to study water movement through the environment, they generally have not been used to examine shorter, more transient events, e.g., rainfall of <25 mm. With the development of robust methods that use isotope ratio infrared spectrometry, evaluating samples has become faster and simpler, allowing more soil and plant samples to be collected and analyzed. Using larger sampling rates can therefore increase the resolution of changes in stable isotopes within an ecosystem, and allows for a better understanding of how quickly rainwater that enters the soil by infiltration is transpired by a plant via root-water uptake. Quantifying rainwater uptake by plants is essential to increase crop production in rainfed agriculture. Thus the objective of this study was to measure the time required by a plant to transpire water from a source of water with a different isotopic signature than the water that the plant was irrigated. To this end, cotton (Gossypium hirsutum (L.)) plants were grown in a greenhouse and the time required for the enriched water added the soil to show up in the meristematic petioles of cotton leaves was measured. The initial divergence from the irrigation water signature occurred as quickly as 4 hours. The water from the sampled petioles then reached equilibrium with the new source water within 12 hours

  17. Studies on separation of boron isotopes by ion exchange

    International Nuclear Information System (INIS)

    Studies have been carried out for the enrichment of boron isotopes by the ion exchange method using various anion exchange resins available. The elementary separation factors and heights equivalent of theoretical plate were measured at different concentrations and flow rates. A number of experiments were performed to study the displacement of borate band on ion exchange columns. The problem of CO2 evolution during displacement was also studied and a solution was found. (author). 9 refs

  18. Investigations of isotopic composition of foodstuff - basic study and applications

    International Nuclear Information System (INIS)

    Study of food isotopic composition play actually an important role in food authenticity and origin control. In Institute of Nuclear Chemistry and technology the subject of study has been investigated for many years. In last time our work is concentrated on the implementation new methods for selected food and improves of our proficiency in laboratory work. The examples of our study results are presented. (author)

  19. Partitioning of ocean and land uptake of CO2 as inferred by delta C-13 measurements from the NOAA Climate Monitoring and Diagnostics Laboratory Global Air Sampling Network

    Science.gov (United States)

    Ciais, Philippe; Tans, Pieter P.; White, James W. C.; Trolier, Michael; Francey, Roger J.; Berry, Joe A.; Randall, David R.; Sellers, Piers J.; Collatz, James G.; Schimel, David S.

    1995-01-01

    Using delta C-13 measurements in atmospheric CO2 from a cooperative global air sampling network, we determined the partitioning of the net uptake of CO2 between ocean and land as a function of latitude and time. The majority of delta C-13 measurements were made at the Institute of Arctic and Alpine Research (INSTAAR) of the University of Colorado. We perform an inverse deconvolution of both CO2 and delta C-13 observations, using a two-dimensional model of atmospheric transport. Also, the discrimination against C-13 by plant photosynthesis, as a function of latitude and time, is calculated from global runs of the simple biosphere (SiB) model. Uncertainty due to the longitudinal structure of the data, which is not represented by the model, is studied through a bootstrap analysis by adding and omitting measurement sites. The resulting error estimates for our inferred sources and sinks are of the order of 1 GTC (1 GTC = 10(exp 15) gC). Such error bars do not reflect potential systematic errors arising from our estimates of the isotopic disequilibria between the atmosphere and the oceans and biosphere, which are estimated in a separate sensitivity analysis. With respect to global totals for 1992 we found that 3.2 GTC of carbon dissolved into the ocean and that 1.5 GTC were sequestered by land ecosystems. Northern hemisphere ocean gyres north of 15 deg N absorbed 2.7 GTC. The equatorial oceans between 10 deg S and 10 deg N were a net source to the atmosphere of 0.9 GTC. We obtained a sink of 1.6 GTC in southern ocean gyres south of 20 deg S, although the deconvolution is poorly constrained by sparse data coverage at high southern latitudes. The seasonal uptake of CO2 in the northern gyres appears to be correlated with a bloom of phytoplankton in surface waters. On land, northern temperate and boreal ecosystems between 35 deg N and 65 deg N were found to be a major sink of CO2 in 1992, as large as 3.5 GTC. Northern tropical ecosystems (equator-30 deg N) appear to be a net

  20. 26 CFR 31.3306(c)(13)-1 - Services of student nurse or hospital intern.

    Science.gov (United States)

    2010-04-01

    ... 26 Internal Revenue 15 2010-04-01 2010-04-01 false Services of student nurse or hospital intern. 31.3306(c)(13)-1 Section 31.3306(c)(13)-1 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF...) § 31.3306(c)(13)-1 Services of student nurse or hospital intern. (a) Services performed as a...

  1. 40 CFR 721.6505 - Polymers of C13C15 oxoalcohol ethoxolates.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Polymers of C13C15 oxoalcohol... Specific Chemical Substances § 721.6505 Polymers of C13C15 oxoalcohol ethoxolates. (a) Chemical substance... polymers of C13C15 oxoalcohol ethoxolates (PMNs P-96-950/951) are subject to reporting under this...

  2. An isotope study of hot springs in Nagano Prefecture

    International Nuclear Information System (INIS)

    The water samples from 28 hotsprings and mineral springs in Nagano Prefecture were examined for their stable isotope ratios of hydrogen, oxygen, carbon and sulfur. The spring water of Kashio was highly saline and rich in heavy isotopes of oxygen and hydrogen. This spring water seems to be the mixture of deep brine and local surface water. The extrapolation of the linear relationship indicated that the deep brine was both isotopically and chemically very similar to the deep brine suggested for the springs at Arima, Takarazuka and Ishibotoke. A yet unknown common origin may be warranted among these postulated brines. The hot springs in Matsushiro are a Na-Ca-Cl type with high content of carbonate. Their hydrogen and oxygen isotope ratios were higher than the local surface water. From the data, these hot springs seemed to be the mixture of fossil sea water and the water of meteoric origin. The water samples from the other hot springs studied were of simple meteoric origin, belonging to the green tuff type water. (J.P.N.)

  3. Isotopic hydrological studies carried out on the Karst water system

    International Nuclear Information System (INIS)

    The isotopic composition and temperature of many karst springs in the area of Trieste (Italy) have been measured for about three and a half years. During the same period the isotopic composition of precipitation has also been systematically studied. The isotopic composition of springs generally shows variations which are markedly shifted in time with respect to those of precipitation. In most of the springs the heavy isotope contents of winter samples are the highest of the whole year. On the contrary, summer samples normally show quite negative δ-values, the most negative of which often refer to the last summer months. The data obtained are explained in terms of variable mixing of waters from two main reservoirs. The less negative reservoir (in terms of δ) is recharged by ''local'' meteoric waters falling on the westernmost section of the karst area whose mean elevation is about 400 m a.s.l. The most negative reservoir is probably recharged by meteoric waters falling on the Slovenian section of the karst, whose mean elevation is about 800-900 m a.s.l. At least in the case of some of the northernmost karst springs, it is likely that a third water system, basically fed by the Isonzo river, flowing north of the karst area, could interfere with the previously mentioned reservoirs, partially controlling the outflow of some springs. 6 figs

  4. Venous obstruction in permanent pacemaker patients: an isotopic study

    International Nuclear Information System (INIS)

    Isotope venography was used to study the venous circulation proximal to the superior vena cava in two groups of pacemaker patients, one with a single endocavitary electrode and the other with multiple pacing catheters. A control group of patients without pacemakers was also studied. Numerous abnormalities were found, especially in the group with multiple electrodes. These findings suggest that venous obstruction is a common complication of endocardial pacing

  5. Venous obstruction in permanent pacemaker patients: an isotopic study

    Energy Technology Data Exchange (ETDEWEB)

    Pauletti, M.; Di Ricco, G.; Solfanelli, S.; Marini, C.; Contini, C.; Giuntini, C.

    1981-01-01

    Isotope venography was used to study the venous circulation proximal to the superior vena cava in two groups of pacemaker patients, one with a single endocavitary electrode and the other with multiple pacing catheters. A control group of patients without pacemakers was also studied. Numerous abnormalities were found, especially in the group with multiple electrodes. These findings suggest that venous obstruction is a common complication of endocardial pacing.

  6. Measurements to assess atmospheric methane and its sources (destinations) on the basis of carbon (14C,13C) and hydrogen (D) isotopes. Kohlenstoff-( sup 14 C, sup 13 C)- und Wasserstoff-(D)-Isotopenmessungen an atmosphaerischem Methan und seinen Quellen (Senken)

    Energy Technology Data Exchange (ETDEWEB)

    Levin, I.; Bergamaschi, P.; Boesinger, R.; Doerr, H.; Junghans, C.; Katruff, L.; Muennich, K.O. (Heidelberg Univ. (Germany, F.R.). Inst. fuer Umweltphysik); Bonani, G. (Eidgenoessische Technische Hochschule, Zurich (Switzerland). Inst. fuer Mittelenergiephysik)

    1989-01-01

    It is the aim of this study to investigate the spatial and temporal variations in the concentration and isotopia of atmospheric methane as well as of its sources and destinations on the European continent. The results thus obtained are planned to be used in connection with the attempts made to draw up an overall balance of methane in the atmosphere. A survey is given of the measuring methods and values determined. (orig./KW).

  7. Application of stable isotopes in environmental studies and food authentication

    International Nuclear Information System (INIS)

    Environmental isotopes of light elements (hydrogen, carbon, nitrogen, oxygen, sulphur, chlorine), are used as modern, specific and reliable technique for studies of global element cycles, hydrology and, recently, more and more for pollution monitoring. Some of them, like tritium (3H) and radioactive carbon (14C) are radioactive, while others are stable (2H, 13C, 15 N, 18O, 34S and 37Cl). After the identification and quantification of pollution, it is of interest to characterize the sources and determine whether the pollution is locally derived or has been transported over long distances. Surface sources of pollution can be designated as natural, industrial, agricultural or domestic. Environmental isotope methods are a powerful tool to follow contributions from different sources, appreciate the effects of efforts to limit the diffusion of a pollutant and identify the isotopic fingerprints of pollutants. Atmospheric sulphur compounds e.g. SO2 and SO42- originate from coal combustion, volcano eruption or are produced by sea microorganisms. Measurements of 34S/32S in the samples are a useful way to distinguish among the sources. Intensive researches concerning analyses of sulphur isotope ratio in coal and different combustion streams (gases, desulphurization product) are going on. Isotopic ratio 34S/32S can be considered as a natural marker for the pollution origin study. Among other hydrological and chemical methods, tritium analysis and methods based on measurement of isotopic ratio of 2H/1H, 34S/32S and 18O/16O in SO42- ions are used for monitoring and prognosis of the ground water quality in the vicinity of Belchatow lignite mine. This is the biggest Polish open mouth mine and with a new proposed expansion (the Szczercow field) will be in operation for the next 50 years. INCT carries on periodical monitoring of ground water in that industrial region. Natural products such as wine, spirits, fruit juices, flavours, oils, and honey are prime targets for fraudulent

  8. Isotope techniques in lake water studies

    International Nuclear Information System (INIS)

    Freshwater lakes are among the most easily exploitable freshwater resources. Lakes are also recognized as major sedimentological features in which stored material can be used to study recent climate and pollution evolution. To adequately preserve these important landscape features, and to use them as climatic archives, an improved understanding of processes controlling their hydrologic and bio-geochemical environments if necessary. This article briefly describes the IAEA activities related to the study of lakes in such areas as lake budget, lake dynamics, water contamination, and paleolimnological investigations

  9. Sulfur and oxygen isotope studies of sulfate reduction

    Science.gov (United States)

    Farquhar, J.; Canfield, D. E.; Bao, H.; Masterson, A.; Johnston, D. T.; Wing, B. A.

    2007-12-01

    I will discuss insights into sulfur and oxygen isotope fractionations of dissimilatory sulfate reduction and specifically insight provided by experiments with natural populations of sulfate-reducing bacteria from Faellestrand, Denmark. The experiments yielded relatively large magnitude sulfur isotope fractionations for dissimilatory sulfate reduction (up to approximately 45 ‰ for 34S/32S), with higher δ18O accompanying higher δ34S, similar to that observed in previous studies. The seawater used in the experiments was spiked by addition of 17O-labelled water and the 17O content of residual sulfate was found to depend on the fraction of sulfate reduced in the experiments. The 17O data provides evidence for recycling of sulfur from metabolic intermediates and for an 18O/16O fractionation of ~25-30 ‰ for dissimilatory sulfate reduction, a magnitude that is consistent with isotopic exchange between a sulfite species and cell water. The molar ratio of oxygen exchange to sulfate reduction was found to be about 2.5. Using recent models of sulfur isotope fractionations we find that our combined sulfur and oxygen isotopic data places constraints on the proportion of sulfate recycled to the medium (78-96 %), the proportion of sulfur intermediate sulfite that was recycled by way of APS to sulfate and released back to the external sulfate pool (~70%) and also that a fraction of the sulfur intermediates between sulfite and sulfide were recycled to sulfate. These parameters can be constrained because of the independent information provided by δ18O, δ34S, 17O labels, and Δ33S.

  10. Utility of radioactive isotope studies in hypersplenism

    International Nuclear Information System (INIS)

    51Cr labelled blood cells were used to estimate red blood cell (RBC) half-life and to judge splenic sequestration in thirty cases of splenomegaly which satisfied routine haematological criteria for hypersplenism. Out of the thirteen cases showing shortened RBC half-life, eleven showed splenic sequestration thus establishing an excellent correlation between these parameters. In over 50% cases, however, radioisotopic studies did not substantiate the diagnosis of hypersplenism. (M.G.B.)

  11. Tracing gas accretion in the Galactic center using isotopic ratios

    CERN Document Server

    Riquelme, D; Martin-Pintado, J; Mauersberger, R; Martin, S; Bronfman, L

    2010-01-01

    Ams: We study the 12C/13C isotopic ratio in the disk of the central molecular zone and in the halo to trace gas accretion toward the Galactic center region in the Milky Way. Methods: Using the IRAM 30m telescope, we observe the J=1-0 rotational transition of HCO+, HCN, HNC and their 13C isotopic substitutions in order to measure the 12C/13C isotopic ratio. We observe 9 positions selected throughout the Galactic center region, including clouds at high latitude; locations where the X1 and X2 orbits associated with the barred potential are expected to intersect; and typical Galactic center molecular clouds. Results: We find a systematically higher 12C/13C isotopic ratio (>40) toward the halo and the X1 orbits than for the Galactic center molecular clouds (20-25). Our results point out to molecular gas which has undergone a different degree of nuclear processing than that observed in the gas towards the inner Galactic center region. Conclusions: The high isotopic ratios are consistent with the accretion of the ga...

  12. Stable isotope composition of atmospheric carbon monoxide. A modelling study

    International Nuclear Information System (INIS)

    This study aims at an improved understanding of the stable carbon and oxygen isotope composition of the carbon monoxide (CO) in the global atmosphere by means of numerical simulations. At first, a new kinetic chemistry tagging technique for the most complete parameterisation of isotope effects has been introduced into the Modular Earth Submodel System (MESSy) framework. Incorporated into the ECHAM/MESSy Atmospheric Chemistry (EMAC) general circulation model, an explicit treatment of the isotope effects on the global scale is now possible. The expanded model system has been applied to simulate the chemical system containing up to five isotopologues of all carbon- and oxygen-bearing species, which ultimately determine the δ13C, δ18O and Δ17O isotopic signatures of atmospheric CO. As model input, a new stable isotope-inclusive emission inventory for the relevant trace gases has been compiled. The uncertainties of the emission estimates and of the resulting simulated mixing and isotope ratios have been analysed. The simulated CO mixing and stable isotope ratios have been compared to in-situ measurements from ground-based observatories and from the civil-aircraft-mounted CARIBIC-1 measurement platform. The systematically underestimated 13CO/12CO ratios of earlier, simplified modelling studies can now be partly explained. The EMAC simulations do not support the inferences of those studies, which suggest for CO a reduced input of the highly depleted in 13C methane oxidation source. In particular, a high average yield of 0.94 CO per reacted methane (CH4) molecule is simulated in the troposphere, to a large extent due to the competition between the deposition and convective transport processes affecting the CH4 to CO reaction chain intermediates. None of the other factors, assumed or disregarded in previous studies, however hypothesised to have the potential in enriching tropospheric CO in 13C, were found significant when explicitly simulated. The inaccurate surface

  13. Nuclear transformations studies in selenium isotopes

    International Nuclear Information System (INIS)

    A compilation is made with regard to the chemical effects produced by nuclear transformations, such as the chemical effects of the beta decay and the chemical effects of the reaction (n,γ) in selenium radioisotopes. As a particular case the chemical effect of the isomeric transition of sup(81m)Se(VI) in potassium selenate crystals marked with radioactive selenium is studied experimentally and the method of adsorption in activated carbon is applied for the analytical separation of the traces of the nuclear isomer tetravalent sup(81b)Se(IV) of one fraction which contains the mixture of the selenium radioisotopes. (author)

  14. Isotopic studies of the aquiferous of Lima

    International Nuclear Information System (INIS)

    Filtrations from Rimac and Blanco rivers and Graton Tunnel (on the Rimac basin, 80 km from Lima city and 2500 m sea level) were studied using artificial tracers and superficial tracers and superficial water analysis. Graton tunnel has a 3 -5 m3/s volume. Domestic and industrial demand of Lima (7 millions inhabitants) is 22 m3/s . Preliminary results suggest that Graton tunnel filtrations do not originate on Rimac or Blanco rivers, but in regions at 4600 m sea level. Detected tritium suggests that water filtrated in Graton tunnel is modern. (authors) 10 refs., 2 figs

  15. Carbon Isotopic Fractionation During Formation of Macromolecular Organic Grain Coatings via FTT Reactions

    Science.gov (United States)

    Nuth, J. A.; Johnson, N. M.; Elsila-Cook, J.; Kopstein, M.

    2011-01-01

    Observations of carbon isotopic fractionation of various organic compounds found in meteorites may provide useful diagnostic information concerning the environments and mechanisms that were responsible for their formation. Unfortunately, carbon has only two stable isotopes, making interpretation of such observations quite problematic. Chemical reactions can increase or decrease the C-13/C-12 ratio by various amounts, but the final ratio will depend on the total reaction pathway followed from the source carbon to the final product, a path not readily discernable after 4.5 billion years. In 1970 Libby showed that the C-13/C-12 ratios of terrestrial and meteoritic carbon were similar by comparing carbon from the Murchison meteorite to that of terrestrial sediments. More recent studies have shown that the C-13/C-12 ratio of the Earth and meteorites may be considerably enriched in C-13 compared to the ratio observed in the solar wind [2], possibly suggesting that carbon produced via ion-molecule reactions in cold dark clouds could be an important source of terrestrial and meteoritic carbon. However, meteoritic carbon has been subjected to parent body processing that could have resulted in significant changes to the C-13/C-12 ratio originally present while significant variation has been observed in the C-13/C-12 ratio of the same molecule extracted from different terrestrial sources. Again we must conclude that understanding the ratio found in meteorites may be difficult.

  16. Fluid inclusion stable isotopes and clumped isotopes thermometry study of Eastern Mediterranean paleoclimate

    Science.gov (United States)

    Matthews, A.; Bar-Matthews, M.; Affek, H. P.; Ayalon, A.; Vonhof, H. B.; Zaarur, S.; Burstyn, Y.

    2012-04-01

    Fluid inclusion (FI) stable isotopes and clumped isotopes thermometry provide powerful tools for reconstructing paleoclimates using speleothems. Clumped isotopes thermometry is a unique tool for paleotemperature determination using the mass 47 anomaly (Δ47), but its application to speleothems is complicated by the occurrence of a kinetic isotope effect (KIE) that accompanies CO2 degassing during carbonate precipitation1. Experimental studies involving the surface precipitation of synthetic calcite2 provide a Δ47 thermometer calibration that takes KIE into account and allows its direct application to speleothems. Complementary, the δDw and δ18Ow values of speleothem FI provide an important proxy for cave water-rainfall paleo-hydrological conditions, together with the data required for construction of the meteoric water line (MWL) relationship. Until recently the main studied parameter is δDw, and the reliability of FI δ18Ow has been questioned because of the possibility of post-depositional isotope exchange with the surrounding calcite. When speleothem calcite δ18Occ is measured, Δ47 temperatures allow δ18Ow to be independently calculated using the calcite-water fractionation relationship. Methods for FI analysis using crushing in a helium stream, TC/EA and continuous flow mass spectrometry (Amsterdam system3) enable both δDw and δ18Ow to be determined, thus allowing measured δ18Ow values to be compared with those calculated from Δ47 temperatures and δ18Occ. We apply these methodologies to paleoclimate study in the Eastern Mediterranean (EM) region during the last 150 ky: in the Soreq Cave from the glacial stage 6 to the last interglacial stage 5e and the last glacial maximum (LGM) to the Holocene, and to the Alpine karst system of the Hermon mountain range (MS) cave4 during the last interglacial and brief warm intervals during the last glacial. Soreq Cave Δ47 data show temperature minima at the termination of stage 6 and the LGM, but the LGM

  17. Deep groundwater study in South Syria, using environmental isotopes

    International Nuclear Information System (INIS)

    Environmental isotopes accompanied by hydrochemical analysis techniques, have been carried out in this study in order to achieve a preliminary evaluation of deep groundwater aquifer of upper Cretaceous, covering the area of Qalamon in the north to the border with Jordan in the south. Deep groundwater in the study area has low salinity with average (500 mg.1-1), varying from 200 mg.1-1 in recharge areas to 2000 mg.1-1 on the rims of Palmyrides range. Hydrochemical facies are generally bicarbonates calcium magnesium, vary in the south to bicarbonates calcium-sodium. Water temperature varies from 15 to 60 Centigrade with regional gradient increasing 3.5 Centigrade per 100 m downward, it is possible to relate it to vertical water movement in accordance with deep fault zones. In addition to possible local variations, particularly in the south on the Jordanian border. Results of stable isotopes of oxygen 18 and deuterium and δ18O/δ2H ratio show that there is complete separation in isotopic content between the group of south in the border with Jordan from the second group in Damascus and Qalamon areas. First group indicate to partial evaporation and lower altitude in recharge areas. Whereas the second group is mixed particularly in western part. Points setting in δ18O/δ2H ratio is mainly attributed to variations in altitude in recharge areas. Hence, δ18O/δ2H ratio shows that most groundwater points are clustered between Global Meteoric Water Line and Mediterranean line. Recharge of this water may represent mixing of the two sources as the distance from recharge areas increase, while most points in Damascus Basin, Anti Lebanon, Qalamon and northern parts of Yarmouk are associated with significant recent recharge through its relation with the Local Meteoric Water Line. Most depleted stable isotopes values have been encountered in the southern part of Damascus depression with overall increase in these isotopes and decrease of C-14 radioactivity beginning from Damascus

  18. Applications of C and N stable isotopes to ecological and environmental studies in seagrass ecosystems.

    Science.gov (United States)

    Lepoint, Gilles; Dauby, Patrick; Gobert, Sylvie

    2004-12-01

    Stable isotopes of carbon and nitrogen are increasingly used in marine ecosystems, for ecological and environmental studies. Here, we examine some applications of stable isotopes as ecological integrators or tracers in seagrass ecosystem studies. We focus on both the use of natural isotope abundance as food web integrators or environmental tracers and on the use of stable isotopes as experimental tools. As ecosystem integrators, stable isotopes have helped to elucidate the general structure of trophic webs in temperate, Mediterranean and tropical seagrass ecosystems. As environmental tracers, stable isotopes have proven their utility in sewage impact measuring and mapping. However, to make such environmental studies more comprehensible, future works on understanding of basic reasons for variations of N and C stable isotopes in seagrasses should be encouraged. At least, as experimental tracers, stable isotopes allow the study of many aspects of N and C cycles at the scale of a plant or at the scale of the seagrass ecosystem. PMID:15556172

  19. Applications of C and N stable isotopes to ecological and environmental studies in seagrass ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Lepoint, Gilles [Centre MARE, Laboratoire d' Oceanologie, Institut de Chimie, B6, Universite de Liege, B-4000 Liege (Belgium)]. E-mail: g.lepoint@ulg.ac.be; Dauby, Patrick [Centre MARE, Laboratoire d' Oceanologie, Institut de Chimie, B6, Universite de Liege, B-4000 Liege (Belgium); Institut Royal des Sciences Naturelles de Belgique, rue Vautier, B1000 Brussels (Belgium); Gobert, Sylvie [Centre MARE, Laboratoire d' Oceanologie, Institut de Chimie, B6, Universite de Liege, B-4000 Liege (Belgium)

    2004-12-01

    Stable isotopes of carbon and nitrogen are increasingly used in marine ecosystems, for ecological and environmental studies. Here, we examine some applications of stable isotopes as ecological integrators or tracers in seagrass ecosystem studies. We focus on both the use of natural isotope abundance as food web integrators or environmental tracers and on the use of stable isotopes as experimental tools. As ecosystem integrators, stable isotopes have helped to elucidate the general structure of trophic webs in temperate, Mediterranean and tropical seagrass ecosystems. As environmental tracers, stable isotopes have proven their utility in sewage impact measuring and mapping. However, to make such environmental studies more comprehensible, future works on understanding of basic reasons for variations of N and C stable isotopes in seagrasses should be encouraged. At least, as experimental tracers, stable isotopes allow the study of many aspects of N and C cycles at the scale of a plant or at the scale of the seagrass ecosystem.

  20. Isotope ratio in stellar atmospheres and nucleosynthesis

    International Nuclear Information System (INIS)

    The determination of isotopic ratios in stellar atmospheres is studied. The isotopic shift of atomic and molecular lines of different species of a certain element is examined. CH and MgH lines are observed in order to obtain the 12C: 13C and 24Mg: 25Mg: 26Mg isotpic ratios. The formation of lines in stellar atmospheres is computed and the resulting synthetic spectra are employed to determine the isotopic abundances. The results obtained for the isotopic ratios are compared to predictions of nucleosynthesis theories. Finally, the concept of primary and secondary element is discussed, and these definitions are applied to the observed variations in the abundance of elements as a function of metallicity. (author)

  1. Isotopic study of waterlogging and salinization in Peshawar valley

    International Nuclear Information System (INIS)

    A detailed account of the application of isotope and geochemical techniques in the study of waterlogging and selenization of agricultural lands in Peshawar valley area is presented. Precipitation samples, surface / groundwater samples and aqueous sulphate were analysed for tritium and stable isotope ratios of hydrogen, oxygen and sulphur. The data show that the artesian aquifer is recharged by the precipitation at high mountain whereas local precipitation and irrigation canal waters are mainly responsible for the recharge and waterlogging in the unconfined aquifer. In some parts of the valley, upward leakage from artesian water is found to cause waterlogging. The valley area contains water recharged after 1953. The chemical quality of the shallow groundwater is quite poor as compared to that of deep groundwater. 18 figs. (author)

  2. Australis: AMS for ultra sensitive trace element and isotopic studies

    Energy Technology Data Exchange (ETDEWEB)

    Sie, S.H.; Suter, G.F. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), North Ryde, NSW (Australia). Div. of Exploration Geoscience

    1993-12-31

    The accelerator mass spectrometer (AMS) at the CSIRO HIAF laboratory is being upgraded to enable in-situ measurements of ultratraces and isotopic-ratios in mineralogical applications. The upgraded system will include a microbeam Cs ion source which is designed to produce better than 50 micrometre diameter Cs beam to enable analyses of monomineralic grains. The Cs primary beam will be mass analysed in order to minimize contamination of the sample. The detection system will be upgraded to enable analyses of elements up to U, at 2 MV terminal voltage for charge states 4 and 5. The system will be known as AUSTRALIS: A.M.S. for Ultra Sensitive TRAce eLement and Isotopic Studies. An overview of the system and the anticipated applications in minerals exploration and mining research are presented. 4 refs., 1 fig.

  3. Theoretical study on isotope separation of an ytterbium atomic beam by laser deflection

    International Nuclear Information System (INIS)

    Isotope separation by laser deflecting an atomic beam is analyzed theoretically. Interacting with a tilted one-dimensional optical molasses, an ytterbium atomic beam is split into multi-beams with different isotopes like 172Yb,173Yb, and 174Yb. By using the numerical calculation, the dependences of the splitting angle on the molasses laser intensity and detuning are studied, and the optimal parameters for the isotope separation are also investigated. Furthermore, the isotope separation efficiency and purity are estimated. Finally a new scheme for the efficient isotope separation is proposed. These findings will give a guideline for simply obtaining pure isotopes of various elements. (atomic and molecular physics)

  4. Isotope study of the Oruro-Caracollo basin (Bolivia)

    International Nuclear Information System (INIS)

    The isotope study was carried out on the Oruro-Caracollo fluvio-lacustrine basin on the Bolivian altiplano (mean altitude 3700 m a.s.l.) 250 km south of La Paz near the town of Oruro and its famous tin, silver and antimony mines. On interpretation, the distributions of natural isotopes (18O, 2H, 3H and 14C) revealed the presence of three different water types: (1) water from the surface aquifer through the alluvial cones at the foot of the Cordillera Oriental to the east; (2) thermal waters on the edges of the sedimentary basin which have little effect on the aquifers studied; (3) and deep circulation water through the Tertiary volcanic basement rock (San Jose mines). It was demonstrated that flooding on the Oruro plateau plays no part in recharge and is totally lost to evaporation. On the basis of 14C activity, a general direction of flow from northeast to southeast was deduced, with an estimated rate of flow of 1 m/a. The isotope data suggest that there is a hydrological division in the basement of the basin between the Kala Kaja and Challapampita well fields; it is also suggested that there is a line or fault running northeast to southeast in Kala Kaja along which water of deep origin rises. (author). 6 refs, 6 figs, 3 tabs

  5. Secondary isotope effects in studies using radiolabelled folate tracers

    International Nuclear Information System (INIS)

    During studies on the whole body metabolism of radioactive folate tracers it has been observed that some forms of isotopically labelled folate are biologically distinguishable from the unlabelled carrier molecules by an as yet unidentified secondary isotope effect. Folates excreted in the urine of rats dosed previously with mixtures of 14C- and 3H-labelled folate derivatives are apparently 3H enriched due to the enhanced absorption of 3H-folate from the intestine, confirmed by studies with everted sac preparations of rat jejunum in which it was found that the 3H-labelled folate in the mixture was transported from the mucosal into the serosal compartment at a faster rate than both the 14C-labelled folate and the unlabelled carrier. Secondary isotope effects were also observed on ion-exchange chromatography, 3H-labelled folates with 3H at the C-9 position eluting fractionally earlier than the corresponding unlabelled or 2-14C folate from DEAE-cellulose. (U.K.)

  6. Molecular dynamics study of hydrogen isotopes migration in amorphous silica

    International Nuclear Information System (INIS)

    Full text of publication follows: Fused silica is a material of interest due to its increasing number of applications in many different technology fields. In thermonuclear fusion it is a key component in a number of diagnostics of the Safety and Control Systems of the ITER machine as well as in the final focusing optics of lasers for NIF. Materials properties of interest (optical absorption, radioluminescence, mechanical properties, oe) are closely related to the presence of defects. These defects can be generated directly by irradiation or by the presence of impurities in the material. Hydrogen is an ubiquitous impurity in this material and, moreover in a fusion reactor environment this material will be exposed to energetic hydrogen isotopes. Hydrogen isotopes will be deposited also on the surface of the fused silica components coming from the reaction chamber. On the other hand, some experimental results show that radiation damage can be different depending on hydrogen content, indicating that a detailed knowledge of the hydrogen role in fused silica should be fully understood. In this work we present molecular dynamics simulations to study the effects of different hydrogen isotopes in this material and their interaction with defects. The interatomic potential developed by Feuston and Garofallini has been used in these studies. The diffusion coefficients and mechanisms of H mobility in fused silica has been calculated and compared with those existing in the literature. (authors)

  7. Molecular dynamics study of hydrogen isotopes migration in amorphous silica

    International Nuclear Information System (INIS)

    Fused silica is a material of interest due to its increasing number of applications in many different technology fields. In thermonuclear fusion it is a key component in a number of diagnostics of the Safety and Control Systems of the ITER machine as well as in the final focusing optics of lasers for NIF. Materials properties of interest (optical absorption, radioluminescence, mechanical properties, ...) are closely related to the presence of defects. These defects can be generated directly by irradiation or by the presence of impurities in the material. Hydrogen is an ubiquitous impurity in this material and, moreover in a fusion reactor environment this material will be exposed to energetic hydrogen isotopes. Hydrogen isotopes will be deposited also on the surface of the fused silica components coming from the reaction chamber. On the other hand, some experimental results show that radiation damage can be different depending on hydrogen content, indicating that a detailed knowledge of the hydrogen role in fused silica should be fully understood. In this work we present molecular dynamics simulations to study the effects of different hydrogen isotopes in this material and their interaction with the defects. The interatomic potential developed by Feuston and Garofallini will be used in these studies. The diffusion coefficients and mechanisms of H mobility in fused silica will be calculated and compared with those existing in the literature. (author)

  8. Isotopic Biogeochemistry

    Science.gov (United States)

    Hayes, J. M.

    1985-01-01

    An overview is provided of the biogeochemical research. The funding, productivity, personnel and facilities are reviewed. Some of the technical areas covered are: carbon isotopic records; isotopic studies of banded iron formations; isotope effects in microbial systems; studies of organic compounds in ancient sediments; and development in isotopic geochemistry and analysis.

  9. Interstellar CN and CH+ in Diffuse Molecular Clouds: 12C/13C Ratios and CN Excitation

    CERN Document Server

    Ritchey, A M; Lambert, D L

    2010-01-01

    We present very high signal-to-noise ratio absorption-line observations of CN and CH+ along 13 lines of sight through diffuse molecular clouds. The data are examined to extract precise isotopologic ratios of 12CN/13CN and 12CH+/13CH+ in order to assess predictions of diffuse cloud chemistry. Our results on 12CH+/13CH+ confirm that this ratio does not deviate from the ambient 12C/13C ratio in local interstellar clouds, as expected if the formation of CH+ involves nonthermal processes. We find that 12CN/13CN, however, can be significantly fractionated away from the ambient value. The dispersion in our sample of 12CN/13CN ratios is similar to that found in recent surveys of 12CO/13CO. For sight lines where both ratios have been determined, the 12CN/13CN ratios are generally fractionated in the opposite sense compared to 12CO/13CO. Chemical fractionation in CO results from competition between selective photodissociation and isotopic charge exchange. An inverse relationship between 12CN/13CN and 12CO/13CO follows ...

  10. Water isotopes and the Eocene. A tectonic sensitivity study

    Science.gov (United States)

    Legrande, A. N.; Roberts, C. D.; Tripati, A.; Schmidt, G. A.

    2009-04-01

    The early Eocene (54 Million years ago) is one of the warmest periods in the last 65 Million years. Its climate is postulated to have been the result of enhanced greenhouse gas concentration, with CO2 roughly 4 times pre-industrial and methane 7 times pre-industrial concentrations. One interesting feature of this period to emerge recently is the intermittent presence of fossilized Azolla, a type of freshwater fern, in the Arctic Ocean. Synchronous (within dating error) with this appearance were major changes in the restriction of the Arctic Ocean and the other global oceans. We investigate this time period using the Goddard Institute for Space Studies ModelE-R, a fully coupled atmosphere-ocean general circulation model that incorporates water isotopes throughout the hydrologic cycle, making it an ideal model to test hypotheses of past climate change and to compare to paleoclimate proxy data. We assess the impact of tectonic variability by using minimal and maximal levels of restriction for the Arctic Ocean seaways. We find that the modulation of connectivity of these basins dramatically alters global salinity distribution, leading to large changes in ocean circulation. Greater restriction of the Arctic Basin is associated with fresh and relatively warmer conditions. The same mechanisms responsible for this redistribution of salt also change the global distribution of water isotopes, and can alias (water isotope) proxy climate signals of warmth.

  11. Target and PADC Track Detectors for Rare Isotope Studies

    Directory of Open Access Journals (Sweden)

    J. Bermudez

    2011-01-01

    Full Text Available A higher yield of rare isotope production methods, for example, isotope separation on-line (ISOL, is expected to be developed for the EURISOL facility. In this paper as a part of the ongoing project, high power-target assembly and passive detector inclusion are given. Theoretical calculations of several configurations were done using Monte Carlo code FLUKA aimed to produce 1015 fiss/s on LEU-Cx target. The proposed radioactive ion beam (RIB production relies on a high-power (4 MW multibody target; a complete target design is given. Additionally we explore the possibility to employ PADC passive detector as a complementary system for RIB characterization, since these already demonstrated their importance in nuclear interactions phenomenology. In fact, information and recording rare and complex reaction product or short-lived isotope detection is obtained in an integral form through latent track formation. Some technical details on track formation and PADC detector etching conditions complete this study.

  12. Total flash evaporation studies for uranium isotope ratio measurements

    International Nuclear Information System (INIS)

    Accurate isotopic ratio measurements on uranium samples are essential for nuclear material accounting, enrichment programs and for geochemical research applications. Thermal ionization mass spectrometry is widely followed for these measurements. Conventional measurement technique involving Faraday Cups demands larger samples and fractionation correction for the measured data when accurate data are required. Total evaporation or total flash evaporation technique (TFE) is reported to circumvent these difficulties. The technique consists of heating the sample to exhaustion while simultaneously acquiring intensities of all the isotopes at respective cups and then computing the isotope ratios from the summed up intensities. A brief account of literature on this technique is given in a recent paper. TFE studies were conducted by us on NBS -uranium standard solution (SRMU-010) and on a depleted uranium sample solution with an objective to explore the possibility of using a relatively small quantities in the range 300-350 ng, compared to 2 μg of uranium generally required for routine measurements using Faraday Cups. The methodology followed and the results obtained are presented in this paper

  13. Theoretical study of cluster radioactivity in Re isotopes

    International Nuclear Information System (INIS)

    Cluster radioactivity or exotic decay is the emission of an entity as a cluster of nucleons with mass number heavier than that of an alpha particle and lighter than that of the lightest fission fragment, without being accompanied by neutron emission. The purpose of the present work is to investigate the probable cluster decays of different proton-rich and neutron-rich isotopes of Re (Z=75) using a fission model approach. Phenomenological fission model is used for the study. The half lives for various types of decay of different Re isotopes are calculated considering the interacting potential as the effective liquid drop one, which is the sum of Coulomb and surface potentials. All possible combinations of parent and cluster for which the Q-value is positive have been considered and found that the probable decay modes in proton-rich isotopes are proton, alpha, 8Be, 12C, and 16O emissions since the half lives for these decays are found to be well within the measurable range (T1/2 30s). The paper shows the plots of calculated half lives and Q values for alpha and probable cluster emissions from neutron-deficient Re isotopes against neutron number of daughter nuclei. It is found that plots for alpha, 8Be, 12C, and 16O decays are similar and appear as mirror reflections. The plots for 8Be, 12C and 16O decays indicate the shell closure at or near N= 82, which is a magic number. This confirms the role of neutron magicity in cluster radioactivity. It is also evident that cluster emissions slow down with increasing neutron number

  14. Applied isotope hydrogeology - a case study in northern Switzerland

    International Nuclear Information System (INIS)

    In 1980, Nagra, the Swiss National Cooperative for the Storage of Radioactive Waste, began a comprehensive field investigation programme to assess the feasibility and safety of a repository for the final disposal of high-level radioactive waste in northern Switzerland. An understanding of the deep groundwater flow regime is needed to predict flow paths, travel times and dilution effects of groundwater moving from a repository location to the biosphere. To asses the flow field, regional and local hydrodynamic models have been prepared. Validation of the hydrodynamic models with the results of the hydrogeochemical investigations will be attempted. The isotopic investigations presented in this report will probably be the most important contribution to this validation. The hydrogeochemical programme started in 1981 with the collection of waters from about 140 springs and wells of different aquifers in northern Switzerland and adjacent areas. Detailed hydrochemical and isotopic analyses have been carried out on these samples. About 60 waters from the Nagra deep boreholes were also sampled and analysed, of which some 40 gave useful results. Additional geochemical and isotopic data on rock material are also available from these boreholes. A literature study yielded complementary hydrochemical data, both from points sampled during the regional programme and from additional points. The purpose of this report is to present all the isotope data collected within the Nagra programme in northern Switzerland. The report also includes the first comprehensive synthesis and interpretation of these data. It is anticipated that special aspects of the data interpretation will be discussed elsewhere in the reviewed scientific literature. (author) figs., tabs., 231 refs

  15. Experimental study on hydrogen isotopes storage on titanium bed

    International Nuclear Information System (INIS)

    As known, the Cernavoda Nuclear Power Plant, equipped with a Canadian reactor of CANDU type, is the most powerful tritium source from Europe. On long term, due to a 6.1016 Bq/year release rate, Cernavoda area will be increasingly contaminated by tritium. Also, the continuous contamination of heavy water from the reactor, induces a diminution of moderation capacity. Therefore, one considers that the use of heavy water with an activity higher than 40 Ci/kg in the moderator and 2 Ci/kg in the cooling fluid is improper. For these reasons, we have developed a detritiation technology, based on catalytic isotopic exchange and cryogenic distillation. Tritium will be removed from the tritiated heavy water, so it occurs the necessity of tritium storing in a special vessel that can provide a high level of protection and safety for environment and personnel. Several metals were tested as storage beds for hydrogen isotopes. One of the reference materials used for storing the hydrogen isotopes is uranium, a material with a great storage capacity, but unfortunately it is a radioactive metal and also can react with the impurities from storage gas. Other metals and alloys as ZrCo, Ti, FeTi are also adequate as storage beds at normal temperature. The paper presents studies about the reaction between hydrogen and titanium used as storage bed for the hydrogen isotopes resulted after the detritiation of tritiated heavy water. The experiments that were made use protium and mixture of deuterium and protium at different storing parameters as process gas. (authors)

  16. Isotopic Analysis of Fingernails as a USGS Open House Demonstration of the Use of Stable Isotopes in Foodweb Studies

    Science.gov (United States)

    Silva, S. R.; Kendall, C.; Young, M. B.; Choy, D.

    2011-12-01

    The USGS Isotope Tracers Project uses stable isotopes and tritium to add a unique dimension of chemical information to a wide range of environmental investigations. The use and application of isotopes is usually an unfamiliar and even esoteric topic to the general public. Therefore during three USGS open house events, as a public outreach effort, we demonstrated the use of stable isotopes by analyzing nitrogen and carbon isotopes from very small fragments of fingernail from willing participants. We titled the exhibit "You Are What You Eat". The results from all participants were plotted on a graph indicating the general influence of different food groups on the composition of body tissues as represented by fingernails. All participants were assigned a number and no personal-identification information was collected. A subset of participants provided us with an estimate of the number of days a week various foods were eaten and if they were vegetarians, vegans or non-vegetarians. Volunteers from our research group were on hand to explain and discuss fundamental concepts such as how foods attain their isotopic composition, the difference between C3 and C4 plants, the effects of assimilation, trophic enrichment, and the various uses of stable isotopes in environmental studies. The results of the fingernail analyses showed the variation of the range of isotopic compositions among about 400 people at each event, the distinct influence of C4 plants (mainly corn and cane sugar) on our carbon isotopic composition, and the isotopic differences between vegetarians and non vegetarians among other details (http://wwwrcamnl.wr.usgs.gov/isoig/projects/fingernails/). A poll of visitors attending the open house event in 2006 indicated that "You Are What You Eat" was among the most popular exhibits. Following the first two open house events we were contacted by a group of researchers from Brazil who had completed a very similar study. Our collaboration resulted in a publication in

  17. A systematic study of Zr and Sn isotopes in the Relativistic Mean Field theory

    OpenAIRE

    Geng, L. S.; Toki, H.; Meng, J.

    2003-01-01

    The ground-state properties of Zr and Sn isotopes are studied within the relativistic mean field theory. Zr and Sn isotopes have received tremendous attention due to various reasons, including the predicted giant halos in the neutron-rich Zr isotopes, the unique feature of being robustly spherical in the region of $^{100}$Sn $\\sim$ $^{132}$Sn and the particular interest of Sn isotopes to nuclear astrophysics. Furthermore, four (semi-) magic neutron numbers, 40, 50, 82 and 126, make these two ...

  18. Applications of stable isotopes to study plant-animal relationships in terrestrial ecosystems

    Institute of Scientific and Technical Information of China (English)

    WANG Jianzhu; LIN Guanghui; HUANG Jianhui; HAN Xingguo

    2004-01-01

    As natural tracers, stable isotopes have been extensively used in plant physiological, ecological and environmental research. Recently, animal physiological ecologists have also applied stable isotope techniques to study plant- animal relationships. The isotopic compositions of animal body generally reflect and integrate their diets over a time period ranging from hours to years to the lifetime of an individual. When animal living habitat changes or animals move to a new environment, the animal isotopic compositions will shift accordingly. Thus, stable isotope signatures of an animal can truly reflect its food sources, habitat, distribution and movement patterns during a given time period. Moreover, by analyzing animal-tissue isotopic compositions at different temporal scales, we can improve our understanding of animal adaptation to environmental changes. Stable isotope technique also provides an ideal tool to study animal foodweb relationship and community structure because of isotopic fractionation during the processes of nutrient assimilation by animals. Stable isotope technique can continuously measure animal trophic position in a foodweb, which can eventually reveal the predator-prey relationship and its role in determining matter balance and energy flow in the entire ecosystem. Stable isotope technique has been one of the most important and efficient tools in studying plant-animal relationship. In this paper, we first review recent advances in the application of stable isotope techniques to plant-animal relationship research then evaluate their advantages and disadvantages, and finally discuss some future directions associated with stable isotope applications to plant-animal relationship research.

  19. Microscopic study of neutron-rich dysprosium isotopes

    International Nuclear Information System (INIS)

    Microscopic studies in heavy nuclei are very scarce due to large valence spaces involved. This computational problem can be avoided by means of the use of symmetry-based models. Ground-state, γ and β bands, and their B(E2) transition strengths in 160-168Dy isotopes, are studied in the framework of the pseudo-SU(3) model which includes the preserving symmetry Q . Q term and the symmetry-breaking Nilsson and pairing terms, systematically parametrized. Additionally, three rotor-like terms are considered, whose free parameters, fixed for all members of the chain, are used to fine tune the moment of inertia of rotational bands and the band head of γ and β bands. The model succesfully describes in a systematic way rotational features in these nuclei and allows to extrapolate toward the midshell nucleus 170Dy. The results presented show that it is possible to study a full chain of isotopes or isotones in the region with the present model. (orig.)

  20. Microscopic study of neutron-rich dysprosium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Vargas, Carlos E. [Universidad Veracruzana, Facultad de Fisica e Inteligencia Artificial, Xalapa (Mexico); Universidad Nacional Autonoma de Mexico, Facultad de Ciencias, Apartado Postal 70-542, Mexico D.F. (Mexico); Velazquez, Victor [Universidad Nacional Autonoma de Mexico, Facultad de Ciencias, Apartado Postal 70-542, Mexico D.F. (Mexico); Lerma, Sergio [Universidad Veracruzana, Facultad de Fisica e Inteligencia Artificial, Xalapa (Mexico)

    2013-01-15

    Microscopic studies in heavy nuclei are very scarce due to large valence spaces involved. This computational problem can be avoided by means of the use of symmetry-based models. Ground-state, {gamma} and {beta} bands, and their B(E2) transition strengths in {sup 160-168}Dy isotopes, are studied in the framework of the pseudo-SU(3) model which includes the preserving symmetry Q . Q term and the symmetry-breaking Nilsson and pairing terms, systematically parametrized. Additionally, three rotor-like terms are considered, whose free parameters, fixed for all members of the chain, are used to fine tune the moment of inertia of rotational bands and the band head of {gamma} and {beta} bands. The model succesfully describes in a systematic way rotational features in these nuclei and allows to extrapolate toward the midshell nucleus {sup 170}Dy. The results presented show that it is possible to study a full chain of isotopes or isotones in the region with the present model. (orig.)

  1. Microscopic study of neutron-rich Dysprosium isotopes

    CERN Document Server

    Vargas, Carlos E; Lerma, Sergio; 10.1140/epja/i2013-13004-1

    2013-01-01

    Microscopic studies in heavy nuclei are very scarce due to large valence spaces involved. This computational problem can be avoided by means of the use of symmetry based models. Ground-state, gamma and beta-bands, and their B(E2) transition strengths in 160-168Dy isotopes, are studied in the framework of the pseudo-SU(3) model which includes the preserving symmetry Q.Q term and the symmetry-breaking Nilsson and pairing terms, systematically parametrized. Additionally, three rotor-like terms are considered whose free parameters, fixed for all members of the chain are used to fine tune the moment of inertia of rotational bands and the band-head of gamma and beta-bands. The model succesfully describes in a systematic way rotational features in these nuclei and allows to extrapolate toward the midshell nucleus 170Dy. The results presented show that it is possible to study full chain of isotopes or isotones in the region with the present model.

  2. 26 CFR 1.501(c)(13)-1 - Cemetery companies and crematoria.

    Science.gov (United States)

    2010-04-01

    ... 26 Internal Revenue 7 2010-04-01 2010-04-01 true Cemetery companies and crematoria. 1.501(c)(13)-1...) INCOME TAX (CONTINUED) INCOME TAXES (CONTINUED) Exempt Organizations § 1.501(c)(13)-1 Cemetery companies and crematoria. (a) Nonprofit mutual cemetery companies. A nonprofit cemetery company may be...

  3. Isotopic constraints on the origin of meteoritic organic matter

    Science.gov (United States)

    Kerridge, J. F.

    1991-01-01

    Salient features of the isotopic distribution of H, C and N in the organic material found in carbonaceous meteorites are noted. Most organic fractions are strongly enriched in D with respect to the D/H ratio characteristic of H2 in the protosolar system; substantial variations in C-13/C-12 ratio are found among different molecular species, with oxidised species tending to be C-13 enriched relative to reduced species; some homologous series reveal systematic decrease in C-13/C-12 with increasing C number; considerable variation in N-15/N-14 ratio is observed within organic matter, though no systematic pattern to its distribution has yet emerged; no interelement correlations have been observed between isotope enrichments for the different biogenic elements. The isotopic complexity echoes the molecular diversity observed in meteoritic organic matter and suggests that the organic matter was formed by multiple processes and/or from multiple sources. However, existence of a few systematic patterns points towards survival of isotopic signatures characteristic of one or more specific processes. The widespread D enrichment implies either survival of many species of interstellar molecule or synthesis from a reservoir containing a significant interstellar component. Several of the questions raised above can be addressed by more detailed determination of the distribution of the H, C and N isotopes among different well-characterized molecular fractions. Thus, the present study is aimed at discovering whether the different amino acids have comparable D enrichments, which would imply local synthesis from a D-enriched reservoir, or very viable D enrichments, which would imply survival of some interstellar amino acids. The same approach is also being applied to polycyclic aromatic hydrocarbons. Because the analytical technique employed (secondary ion mass spectrometry) can acquire data for all three isotopic systems from each molecular fraction, any presently obscured interelement

  4. Isotope hydrology studies on water resources in western Rajasthan

    International Nuclear Information System (INIS)

    Environmental isotope studies in the Jalore and Barmer areas show that deep groundwaters have depleted 2H and 18O compared to the present day precipitation and have negligible tritium. Radiocarbon levels indicate groundwater ages ranging from 2400 to 7400 BP. Shallow groundwaters, on the other hand, show bomb tritium indicating some component of modern recharge. Studies on the effect of the Indira Gandhi canal on groundwater environment helped in differentiating the areas waterlogged by canal seepage and those affected by return flow of irrigation. A study on the buried channel of the legendary Saraswati river in Jaisalmer district indicates shallow waters are old with 14C content of 54.9 pMC to 58.8 pMC (uncorrected ages: 4950 to 4400 BP) with a velocity of about 20 m/a. (author). 15 refs., 7 figs., 2 tabs

  5. Isotope studies on dynamics and sedimentation in Lake Naini, India

    International Nuclear Information System (INIS)

    Understanding hydrodynamics of a water body like a lake is a prerequisite for planning and managing its use. In the present study, isotope techniques are employed to study the dynamics and sedimentation pattern of Lake Naini, in India. From the study a few observations are made: (i) the Lake is a warm monomictic one; (ii) the presence of a centrally submerged ridge in the Lake plays a vital role in the intermixing of the Lake's two sub-basins; (iii) the Lake-Groundwater system is a flow-through type and (iv) the Lake is not shallowing at a rate reported by earlier investigators and has different depositional zones with constant/varying sedimentation rates. A Tritium and Water Balance Model is developed to estimate the water retention time of the Lake and also the groundwater residence time between precipitation and input to the Lake. (author)

  6. Concrete under sulphate attack: an isotope study on sulphur sources.

    Science.gov (United States)

    Mittermayr, Florian; Bauer, Christoph; Klammer, Dietmar; Böttcher, Michael E; Leis, Albrecht; Escher, Peter; Dietzel, Martin

    2012-01-01

    The formation of secondary sulphate minerals such as thaumasite, ettringite and gypsum is a process causing severe damage to concrete constructions. A major key to understand the complex reactions, involving concrete deterioration is to decipher the cause of its appearance, including the sources of the involved elements. In the present study, sulphate attack on the concrete of two Austrian tunnels is investigated. The distribution of stable sulphur isotopes is successfully applied to decipher the source(s) of sulphur in the deteriorating sulphate-bearing minerals. Interestingly, δ(34)S values of sulphate in local groundwater and in the deteriorating minerals are mostly in the range from+14 to+27 ‰. These δ(34)S values match the isotope patterns of regional Permian and Triassic marine evaporites. Soot relicts from steam- and diesel-driven trains found in one of the tunnels show δ(34)S values from-3 to+5 ‰, and are therefore assumed to be of minor importance for sulphate attack on the concretes. In areas of pyrite-containing sedimentary rocks, the δ(34)S values of sulphate from damaged concrete range between-1 and+11 ‰. The latter range reflects the impact of sulphide oxidation on local groundwater sulphate. PMID:22321257

  7. Delayed Particle Study of Neutron Rich Lithium Isotopes

    CERN Multimedia

    Marechal, F; Perrot, F

    2002-01-01

    We propose to make a systematic complete coincidence study of $\\beta$-delayed particles from the decay of neutron-rich lithium isotopes. The lithium isotopes with A=9,10,11 have proven to contain a vast information on nuclear structure and especially on the formation of halo nuclei. A mapping of the $\\beta$-strength at high energies in the daughter nucleus will make possible a detailed test of our understanding of their structure. An essential step is the comparison of $\\beta$-strength patterns in $^{11}$Li and the core nucleus $^{9}$Li, another is the full characterization of the break-up processes following the $\\beta$-decay. To enable such a measurement of the full decay process we will use a highly segmented detection system where energy and emission angles of both charged and neutral particles are detected in coincidence and with high efficiency and accuracy. We ask for a total of 30 shifts (21 shifts for $^{11}$Li, 9 shifts $^{9}$Li adding 5 shifts for setting up with stable beam) using a Ta-foil target...

  8. Chemical and environmental isotope study of precipitation in Syria

    International Nuclear Information System (INIS)

    The rain waters from a network covering 9 meteorological stations distributed mainly in the western part of Syria have been investigated using chemical and environmental isotope techniques during a period of 5 months from December 1989 to April 1990. The chemistry of rain waters falling over the mountainous stations shows a low solute concentration (16-55 mg/L) comparing with those falling over the coastal and anterior stations (36-150 mg/L). The study shows also that the rain water are generally characterized by a high deuterium excess (d = 19 per mille) comparing with that of the global meteoric waters (d = 10 per mille). Mean while, the estimated deuterium excess is found to be lower than that given for the eastern Mediterranean meteoric water (d = 22 per mille). The altitude effect is shown up by a depletion of heavy stable isotopes of about -0.23 per mille and -1.65 per mille per 100 meters for δoxygen-18 and δdeuterium, respectively. The spatial distribution pattern of tritium contents shows a gradual build up with the increasing distance from the Syrian coast. The weighted mean tritium content in rain waters falling over the country is estimated to be around 9.5 TU during the period of observation. (author). 22 refs, 9 figs, 2 tabs

  9. Experimental study on stable isotopic fractionation of evaporating water under varying temperature

    Institute of Scientific and Technical Information of China (English)

    Hai-ying HU; Wei-min BAO; Tao WANG; Si-min QU

    2009-01-01

    The variation of stable isotope ratios in natural waters provides valuable information that can be used to trace water movement. Evaporation plays a crucial role in determining the variation of stable isotopes. In this paper, several evaporation experiments were conducted in order to study the stable isotopic fractionation mechanism of water and analyze the influence of different temperatures on evaporation fractionation. Three group experiments of water evaporation under different temperatures and initial isotopic values were carried out. The results show that fractionation factors of hydrogen and oxygen may increase with temperature, and the average enrichment degree of hydrogen isotope D is 3.432 times that of oxygen isotope 18O. The results also show that the isotopic composition of the initial water has little influence on water evaporation fractionation, which is mainly affected by the state variables in the evaporation process, such as temperature. This research provides experimental data for further understanding the evaporation fractionation mechanism.

  10. Carbon isotopic fractionation in heterotrophic microbial metabolism

    Science.gov (United States)

    Blair, N.; Leu, A.; Munoz, E.; Olsen, J.; Kwong, E.; Des Marais, D.

    1985-01-01

    Differences in the natural-abundance carbon stable isotopic compositions between products from aerobic cultures of Escherichia coli K-12 were measured. Respired CO2 was 3.4 percent depleted in C-13 relative to the glucose used as the carbon source, whereas the acetate was 12.3 percent enriched in C-13. The acetate C-13 enrichment was solely in the carboxyl group. Even though the total cellular carbon was only 0.6 percent depleted in C-13, intracellular components exhibited a significant isotopic heterogeneity. The protein and lipid fractions were -1.1 and -2.7 percent, respectively. Aspartic and glutamic acids were -1.6 and +2.7 percent, respectively, yet citrate was isotopically identical to the glucose. Probable sites of carbon isotopic fractionation include the enzyme, phosphotransacetylase, and the Krebs cycle.

  11. Isotope studies of dolomite formation under sedimentary conditions

    Science.gov (United States)

    Clayton, R.N.; Jones, B.F.

    1968-01-01

    Measurements of stable isotope abundances of the carbonate portion of the sediment in Deep Springs Lake, California, indicate the presence of at least three phases: a magnesian calcite, a primary sedimentary dolomite, and a detrital dolomite. The former two have isotopic compositions consistent with precipitation at isotopic equilibrium from waters of the lake area. The measured isotopic fractionation factor between sedimentary dolomite and its interstitial water is 1.0351, which is outside the range possible for calcite-water. This indicates that the dolomite has formed by direct crystallization from solution and not from a caloite precursor without further isotope exchange. Isotopic and X-ray evidence does not support the contention of Peterson et al. (1966) that Deep Springs Lake dolomite crystals grow by means of a calcite-like surface layer. ?? 1968.

  12. Isotopic exchange in ion-molecule reactions: interstellar implications

    International Nuclear Information System (INIS)

    The results of a study of the rates of isotopic exchange in several positive ion/molecule reactions are outlined. The data were obtained over the temperature range 90 - 550 K using a SIFT apparatus. Reversible reactions of the kind: 13C+ + 12CO reversible 12C+ + 13CO were studied and the rate coefficients were determined. Other similar reactions studied were those between HCO+ and CO in which the carbon and oxygen were variously isotopically labelled. Differences between the rate coefficients were apparent at the lower temperatures which, it is suggested, contribute to the observed enhanced concentrations of the rarer isotopes in interstellar CO and HCO+. Isotopic exchange in the reactions of CH+, CH2+ and CH3+ with HD and D2 and in the reactions of CD+, CD2+ and CD3+ with HD and H2 has also been studied and these data are briefly discussed. (Auth.)

  13. Isotope labeling for NMR studies of macromolecular structure and interactions

    Energy Technology Data Exchange (ETDEWEB)

    Wright, P.E. [Scripps Research Institute, La Jolla, CA (United States)

    1994-12-01

    Implementation of biosynthetic methods for uniform or specific isotope labeling of proteins, coupled with the recent development of powerful heteronuclear multidimensional NMR methods, has led to a dramatic increase in the size and complexity of macromolecular systems that are now amenable to NMR structural analysis. In recent years, a new technology has emerged that combines uniform {sup 13}C, {sup 15}N labeling with heteronuclear multidimensional NMR methods to allow NMR structural studies of systems approaching 25 to 30 kDa in molecular weight. In addition, with the introduction of specific {sup 13}C and {sup 15}N labels into ligands, meaningful NMR studies of complexes of even higher molecular weight have become feasible. These advances usher in a new era in which the earlier, rather stringent molecular weight limitations have been greatly surpassed and NMR can begin to address many central biological problems that involve macromolecular structure, dynamics, and interactions.

  14. NMR study of the isotopically engineered Ge single crystals

    International Nuclear Information System (INIS)

    We report on the first NMR study of 73Ge nuclear spin decoherence in germanium single crystals with different abundance of the 73Ge isotope. Hahn echo decays are well fit by a superposition of two exponentials. The deviation from the single exponential is more pronounced in the more spin-diluted sample, causing long-lived echoes. We show that the decay of these echoes becomes slower with the reduction of 73Ge abundance and is therefore caused by dipole-dipole interaction, reflecting the fundamental decoherence process in the spin system. The fast decay at the beginning of the relaxation process is shown to be mainly caused by the quadrupole interaction. Our experimental findings are supported by the calculations of Hahn echo decays in the germanium crystals under study. Quite good agreement between the theory and experiment is demonstrated.

  15. Isotope Fractionation Studies in Prestellar Cores: The Case of Nitrogen

    Science.gov (United States)

    Milam, Stefanie N.; Charnley, Steven B.

    2011-01-01

    Isotopically fractionated material is found in many solar system objects, including meteorites and comets. It is considered, in some cases, to trace interstellar material that was incorporated into the solar system without undergoing significant processing, thus preserving the fractionation. In interstellar molecular clouds, ion-molecule chemistry continually cycles nitrogen between the two main reservoirs - N and N2 - leading to only minor N-15 enrichments. Charnley and Rodgers showed that depletion of CO removes oxygen from the gas and weakens this cycle such that significant N-15 fractionation can occur for N2 and other N-bearing species in such cores. Observations are being conducted at millimeter and submillimeter wavelengths employing various facilities in order to both spatially and spectrally, resolve emission from these cores. A preliminary study to obtain the N-14/N-15 ratio in nitriles (HCN and HNC) was conducted at the Arizona Radio Observatory's 12m telescope on Kitt Peak, AZ. Spectra were obtained at high resolution (0.08 km/s) in order to resolve dynamic properties of each source as well as to resolve hyperfine structure present in certain isotopologues. This study included four dark cloud cores, observed to have varying levels of molecular depletion: L1521E, L1498, L1544, and L1521F. Previous studies of the N-14/N-15 ratio towards LI544 were obtained with N2H+ and NIH3, yielding ratios of 446 and >700, respectively. The discrepancy observed in these two measurements suggests a strong chemical dependence on the fractionation of nitrogen. Ratios (C,N, and D) obtained from isotopologues for a particular molecule are likely tracing the same chemical heritage and are directly comparable within a given source. Results and comparisons between the protostellar evolutionary state and isomer isotope fractionation as well as between other N-bearing species will be presented.

  16. Iron-Isotopic Fractionation Studies Using Multiple Collector Inductively Coupled Plasma Mass Spectrometry

    Science.gov (United States)

    Anbar, A. D.; Zhang, C.; Barling, J.; Roe, J. E.; Nealson, K. H.

    1999-01-01

    The importance of Fe biogeochemistry has stimulated interest in Fe isotope fractionation. Recent studies using thermal ionization mass spectrometry (TIMS) and a "double spike" demonstrate the existence of biogenic Fe isotope effects. Here, we assess the utility of multiple-collector inductively-coupled plasma mass spectrometry(MC-ICP-MS) with a desolvating sample introduction system for Fe isotope studies, and present data on Fe biominerals produced by a thermophilic bacterium. Additional information is contained in the original extended abstract.

  17. Isotopic studies relative to the Oklo natural fission reactors

    International Nuclear Information System (INIS)

    It has been clearly demonstrated that natural fission reactors operated about 2 109 years ago, in rich uranium one deposits of the Oklo mine in the Republique of Gabon. Six reactions zones have been identified in which approximately six tons of 235U were consumed and the same amount of fission products deposited in the ground. These fission products, their filiation isotopes and nuclei formed from neutron captures are precious tracers, which now can be analysed on well localized samples, to obtain informations on the stability in soil of such elements and data on the nuclear parameters and characteristics of the nuclear reactors. The studies which have been developed at Saclay concern several aspects of this phenomenon: the migrations of fission products, the age of the nuclear reaction, the date of the uranium deposit and the temperature of the reaction zones during the operation of the reactors

  18. Decay studies of neutron deficient rare earth isotopes with OASIS

    Energy Technology Data Exchange (ETDEWEB)

    Gilat, J.; Nitschke, J.M.; Wilmarth, P.A.; Vierinen, K.; Firestone, R.B.

    1987-09-01

    We report results on the decay of /sup 124/Pr, /sup 124,125/Ce, /sup 124,125/La, /sup 134-136/Eu, /sup 134-136/Sm, /sup 134-136/Pm, /sup 144/Ho, /sup 141,142,144/Dy, /sup 140,141,142,144/Tb, /sup 140-142/Gd, and /sup 140-142/Eu, produced by /sup 92/Mo(H.I.,xpyn) reactions at the Berkeley SuperHILAC, and studied with the OASIS on-line mass separator facility. Half-lives, delayed proton branching ratios, ..gamma..-ray energies and intensities, partial decay schemes and several J/sup ..pi../ assignments are presented. Level systematics of the even mass Nd and Sm isotopes and of the nu h/sub 11/2/ - nu s/sub 1/2/ isomers for N = 77 are discussed.

  19. Isotopes to Study the coastal aquifer plain, Cap Bon, Tunisia

    International Nuclear Information System (INIS)

    The study area is located in the northeastern part of Tunisia about 60 km south of the Tunis city. It is bounded by the Gulf of Haematite in the East, Djebel Sidi Aberahmane in the West, The town of Nabeul in the south and the area of the town Kelibia in the north. The landscape is a coastal plain slightly sloping (3%) towards the sea. The groundwater of the Oriental coast aquifer system occurs mainly at two levels, a shallow aquifer up to depths of about 50 m whose reservoir is consisted by sediments of the Plio quaternary and a deep aquifer between about 150 and 400 m located in the sand stone formations of Miocene of the anticline of Djebel Sidi Abderrahmene. The climate of the region is semi-arid to sub-humid and of Mediterranean type. There are no perennial rivers in this region; but intense storms occasionally cause surface runoff, which is discharged by the oueds. The study is related to a technical cooperation project with the International Atomic Energy Agency, Vienna, Austria, aimed at the use of isotope techniques to study the seawater intrusion into the coastal aquifers of Cap Bon in Tunisia. In this regard, a better understanding of the recharge and flow regime as well as the origin or salinity of the groundwater was required. To reach this goal, isotope and geochemical investigations were carried out. Water samples were taken from wells, boreholes from deep and shallow aquifer of the Oriental coastal aquifer located between Beni Khiar in the south and Kelibia in the north. The samples were analysed for their chemical and isotopic compositions (18O, 2H, 3H, 13C, 14C, 34S). In the following, the results of these analyses are presented and discussed in terms of the recharge and flow regime of the groundwater and the origin and evolution of its salinity. The results of geochemical and isotopic studies have shown that the groundwater is very eterogeneous and suggest the aquifer is replenished by recent water coming from direct infiltration from rain. At

  20. Decay studies of neutron deficient rare earth isotopes with OASIS

    International Nuclear Information System (INIS)

    We report results on the decay of 124Pr, /sup 124,125/Ce, /sup 124,125/La, /sup 134-136/Eu, /sup 134-136/Sm, /sup 134-136/Pm, 144Ho, /sup 141,142,144/Dy, /sup 140,141,142,144/Tb, /sup 140-142/Gd, and /sup 140-142/Eu, produced by 92Mo(H.I.,xpyn) reactions at the Berkeley SuperHILAC, and studied with the OASIS on-line mass separator facility. Half-lives, delayed proton branching ratios, γ-ray energies and intensities, partial decay schemes and several J/sup π/ assignments are presented. Level systematics of the even mass Nd and Sm isotopes and of the nu h/sub 11/2/ - nu s/sub 1/2/ isomers for N = 77 are discussed

  1. Pb Isotope Study of Some Nonferrous Metallic Deposits in China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Based on Pb-Pb isochron data of more than 40 Precambrian polymetallic deposits, the authors consider that there are four mineralization periods for the Precambrian copper deposits in China, and the major copper deposits were formed at about 1800 Ma; there are three mineralization periods for gold deposits formed from Archaean to Proterozoic. By studying hundreds of lead isotope data from some Mesozoic continental subvolcanic Cu and Ag polymetallic deposits and fine-disseminated gold deposits, the authors found that the calculation based on the lead single-stage evolution model or two-stage evolution model cannot give the true ore-forming ages but can provide more information about mineralization and material sources of the deposits.

  2. Isotope study in the Alpine karst region of Rawil (Switzerland)

    International Nuclear Information System (INIS)

    An isotope study in the karst of the high Alps in Switzerland is described. From 1973 to 1978 discharge, 3H, delta18O, conductivity and temperature were measured in representative springs. The springs are influenced by snowmelt in late spring and summer, by rain in late summer and autumn, and in the winter period, when infiltration stops, by reservoir water. Since tritium in precipitation in the last years scattered irregularly in time and space, the residence time of winter baseflow (2-4 years) could not be determined very precisely. The pronounced difference in delta18O between several springs allowed us to estimate the difference in mean altitude of their recharge areas. (orig.)

  3. Reservoir souring and sulphur isotopes: A case study

    International Nuclear Information System (INIS)

    Reservoir souring is one of the main problems that can occur during the exploitation of a given oil field. H2S sources must be recognized in order to solve or mitigate their pernicious effects. Causes include microbial sulfate to sulfur reduction (BSR). thermochemical sulfate to sulfur reduction (TSR), thermal hydrolysis, hydrolysis of metal sulfides and desorption of H2S from formation sediments. References in this matter include Hunt(1996), Krouse and Grinenko (1988), Krouse (1977), Ligthelm, et al.(1991), Machel (1987,2001), Machel, et al. (1995), Machel and Foght (2000), Orr(1977), Thode(1981), Worden et al. (1995a,b). A research survey in a soured oil field was carried about to determine the origin of H2S using, in a first step, sulfur isotopes in the produced gas. We present here the data and information of this case study. Some details are still confidential, so our maps have only Gauss-Krueger coordinates (author)

  4. Groundwater salinity study in the Mekong Delta using isotope techniques

    International Nuclear Information System (INIS)

    Environmental isotopes D, 18O and chemical composition were used for study of recharge and salinization of groundwater in the are located between Bassac and Mekong Rivers. The results showed that: (a) Pleistocene aquifers are recharged through flood plains and outcrops located at the same altitude. The sanility of groundwater in these aquifers is mostly due to dissolution of the aquifer material, (b) Pliocene and Miocene aquifers receive recharge through outcrops located at the higher altitude on the northeast extension of the Delta and Cambodia. The salinity of groundwater in the coastal region of the aquifer is attributable to sea water intrusion. There appears to be significant retention of sea water in the coastal sediment during intrusion. (Author)

  5. Selected applications of isotopes in studies of ocean climate

    International Nuclear Information System (INIS)

    Full text: We present and discuss applications of isotope and other tracer data (3H, 3 He, Ne and 18O) to studies of ocean climate. Specifically, we address the variability of deep water formation the Greenland Sea, the variability in Arctic Ocean freshwater components, and the addition of glacial meltwater to the shelves around Antarctica. Changes in deep water formation rates in the Greenland Sea (ca. 80% from 0.5 to 0.1 Sv) were determined using a time series of tritium/3 He data. Reduction of the fraction of meteoric water along a section across the Eurasian Basin of the Arctic Ocean occupied in 1991 and 1996 were derived from δ18O and salinity measurements. Ne and δ18O data were used to calculate fractions of glacial meltwater (ca. 4 per mille) in plumes of ice shelf water flowing out from underneath the Ross Ice Shelf. (author)

  6. Petrologic and oxygen isotopic study of ALH 85085-like chondrites

    Science.gov (United States)

    Prinz, M.; Weisberg, M. K.; Clayton, R. N.; Mayeda, T. K.; Ebihara, M.

    1994-07-01

    Four meteorites (PAT 91546, PCA 91328, PCA 91452, PCA 91467) petrologically similar to ALH 85085 chondrite have now been found. Previous studies of ALH 85085 showed it be a new kind of CR-related microchondrule-bearing chondrite, although one called it a sub-chondrite. The purpose of this study is to learn more about ALH 85085-like meteorites and their relationship to CR and CR-related (LEW 85332, Acfer 182, Bencubbin) chondrites. The methods used included petrology, INA bulk chemical analysis (PAT 91546, PCA 91467), and O isotopic analyses of the whole rocks and separated chondrules and dark inclusions (DIs) from PAT 91546. Since microchondrules and fragments are approximately 20 microns it was necessary to analyze composite samples for O; one was of approximately 100 chondrules, and another was of 5 DIs. Petrologically, the four meteorites are similar to ALH 85085, and there is no basis for determining if all of them, or any combinations, are paired. Mineralogically, olivine and pyroxene are highly magnesian FeNi metal generally has 3-10% Ni, and has a positive Ni-Co correlation similar to that in CR and CR-related chondrites. Refractory inclusions are similar in size to the chondrules and have the following assemblages: (1) hibonite-perovskite, (2) melilite-fassaite-forsterite, (3) grossite (Ca-dialuminate)-melilite-perovskite, (4) spinel-melilite, and (5) spinel-pyroxene aggregates. Chemically, INA analyses indicate that PAT 91546 and PCA 91467 are generally similar to ALH 85085. Oxygen isotopic analyses of the four whole-rock compositions fall along the CR mixing line as does ALH 85085; they are also close to LEW 85332, Acfer 182, and Bencubbin. This supports the concept that these are all CR-related chondrites. Even stronger support is found in the compositions of the chondrules and DIs in PAT 91546, which also plot on or near the CR line.

  7. USE OF STABLE ISOTOPES IN ENVIRONMENTAL AND FORENSIC GEOCHEMISTRY STUDIES

    Science.gov (United States)

    Stable carbon and hydrogen isotopes have been used for many decades in the petroleum industry, but the development of combined gas chromatography-isotope ratio mass spectrometry (GCIRMS) has led to a virtual explosion in application of this technique not only in petroleum explora...

  8. Systematic AMD+GCM Study of Structure of Carbon Isotopes

    International Nuclear Information System (INIS)

    The structure of low-lying states of the carbon isotopes is investigated using the extended version of the Antisymmetrized Molecular Dynamics (AMD) Multi-Slater Determinant model. We can reproduce reasonably well many experimental data for carbon isotopes 12C-22C. A special approach is adopted for 15C to better describe the tail of the wave function

  9. Isotopic study of water origin in salt mines in Poland

    International Nuclear Information System (INIS)

    The most important results of isotopic analyses carried out so far in salt mines in Wieliczka, Bochnia, Klodawa, Wapno and Inowroclaw are presented. Discussion of these results for individual leakages proofs that isotopic methods are fully useful in determining of the origin of water appearing in salt mines. (author)

  10. Isotope analytics for the evaluation of the feeding influence on the isotope ratio in beef samples; Isotopenanalytik zur Bestimmung des Einflusses der Ernaehrung auf die Isotopenzusammensetzung in Rinderproben

    Energy Technology Data Exchange (ETDEWEB)

    Herwig, Nadine

    2010-11-17

    Information about the origin of food and associated production systems has a high significance for food control. An extremely promising approach to obtain such information is the determination of isotope ratios of different elements. In this study the correlation of the isotope ratios C-13/C-12, N-15/N-14, Mg-25/Mg-24, and Sr-87/Sr-86 in bovine samples (milk and urine) and the corresponding isotope ratios in feed was investigated. It was shown that in the bovine samples all four isotope ratios correlate with the isotope composition of the feed. The isotope ratios of strontium and magnesium have the advantage that they directly reflect the isotope ratios of the ingested feed since there is no isotope fractionation in the bovine organism which is in contrast to the case of carbon and nitrogen isotope ratios. From the present feeding study it is evident, that a feed change leads to a significant change in the delta C-13 values in milk and urine within 10 days already. For the deltaN-15 values the feed change was only visible in the bovine urine after 49 days. Investigations of cows from two different regions (Berlin/Germany and Goestling/Austria) kept at different feeding regimes revealed no differences in the N-15/N-14 and Mg-26/Mg-24 isotope ratios. The strongest correlation between the isotope ratio of the bovine samples and the kind of ingested feed was observed for the carbon isotope ratio. With this ratio even smallest differences in the feed composition were traceable in the bovine samples. Since different regions usually coincide with different feeding regimes, carbon isotope ratios can be used to distinguish bovine samples from different regions if the delta C-13 values of the ingested feed are different. Furthermore, the determination of strontium isotope ratios revealed significant differences between bovine and feed samples of Berlin and Goestling due to the different geologic realities. Hence the carbon and strontium isotope ratios allow the best

  11. The application of uranium isotopes to the study of sandstone type uranium deposits

    International Nuclear Information System (INIS)

    Based on the study of composition of uranium isotopes in deposits No.512, the composition distribution of uranium isotope for the uranium deposits of sandstone type are discussed. According to the distribution of uranium isotope samples in different oxidation-reduction zones, the region A should be named as the region of geochemical conflict. The distribution of uranium isotope composition is not only can be used to predict the location of uranium ore body, but also can be used to study the rolling of the roll during the process of the ore body formation. (authors)

  12. The rare gases isotopes used in geophysical studies

    International Nuclear Information System (INIS)

    Rare gas isotopes are largely used in many studies regarding the different aspects of the geophysical and geochemical processes happening at geological and cosmological time scale. In the Herculane Spa area (southwestern part of Romania) there is a long and deep fissure following the Cerna river canyon as well as many transversal fissures. The geothermal water sources (springs), always accompanied by large amounts of gases, are met where these fissures cross. The presence of granite rocks at the surface is another remarkable characteristic of this area. Between 1980-1990 a series of measurements were made especially regarding the helium concentration in the gases released from these geothermal sources. Nitrogen and methane are the main components of released gases, and high helium and radon concentrations were also found. The composition of the gases was determined by using a Dempster mass spectrometer, and the radon from gases (together with the rate of exhalation from the ground) was determined by gamma spectrometry. The argon isotopes were analyzed by means of quadrupole mass spectrometer (AMP-4). Near transversal fissures, the radon exhalation rates have higher values compared to the other measurements in this area. The ratio 4 He/20 Ne > 400 is a very good indicator of the fact that these gases are pure (they do not contain atmospheric air) and they come from depth. The ratios 4 He/40 Ar and 40 Ar/36 Ar suggest that the helium in these sources may have a not negligible part of primordial helium arising from the earth mantle. Still, only the ratio 3 He/4 He can make difference. A table is given containing the ratios 4 He/20 Ne, 4 He/N2, 4 He/40 Ar, 40 Ar/N2, 40 Ar/36 Ar and 38 Ar/36 Ar as measured in four places from Cerna and Mehadica Valleys. (authors)

  13. Applications of stable isotopes in environmental studies at the University of Liege

    OpenAIRE

    Sturaro, Nicolas; Borges, Alberto; Das, Krishna; Dauby, Patrick; Gobert, Sylvie; Mascart, Thibaud; Michel, Loïc; Remy, François; Lepoint, Gilles

    2015-01-01

    Measurement and use of stable isotope ratios have a long history at the University of Liege (Belgium). Since at least 30 years, applications of stable isotopes in marine ecosystems have been developed within the Laboratory of Oceanology and, more recently, within the Chemical Oceanography Unit. In the Laboratory of Oceanology, one research axis is the measurement of stable isotope composition (C, N, S) in organic matter to delineate trophic web structure and to study animal diet, their trophi...

  14. Study on atmospheric hydrogen enrichment by cryopump method and isotope separation by gas chromatography

    International Nuclear Information System (INIS)

    To obtain the information of source of atmospheric hydrogen tritium an analysis of tritium isotopes is thought to be effective. So an atmospheric hydrogen enrichment apparatus and a cryogenic gas chromatographic column were made. Experiments were carried out to study the performance of cryopump to enrich atmospheric hydrogen and the column to separate hydrogen isotopes that obtained by cryopump method. The cryopump was able to process about 1000 1 atmosphere and the column was able to separate hydrogen isotopes with good resolution. (author)

  15. Isotopic studies of fresh-saline groundwaters, Outokumpu, Finland

    International Nuclear Information System (INIS)

    relationships, could persist close to the surface, and that the zone A - zone B transition is the result of progressive dilution of the saline waters by influx of modern meteoric fresh water at the surface. The 87Sr/86Sr of the zone B water is uniform at ∼0.724 and is not affected by local extreme variations in the lithology and 87Sr/86Sr of the host rocks. The composition of the water thus is clearly not influenced by local water-rock interaction; the water has been well mixed subsequent to obtaining its dissolved load, possibly derived from interaction with plagioclase-rich assemblages. The zone C saline waters have still lower 87Sr/86Sr ratios (≤0.723). The combined data suggest that the zone C waters have evolved by interaction with Ca- and Mg-bearing minerals with low Rb/Sr ratios. The oxygen and hydrogen isotopic results imply the involvement of clay minerals. The data support previous work which has shown that 87Sr/86Sr measurements on groundwaters are of great value in studying mixing phenomena and determining the origin of dissolved material

  16. Surface Nb-ALLOYING on 0.4C-13Cr Stainless Steel: Microstructure and Tribological Behavior

    Science.gov (United States)

    Yu, Shengwang; You, Kai; Liu, Xiaozhen; Zhang, Yihui; Wang, Zhenxia; Liu, Xiaoping

    2016-02-01

    0.4C-13Cr stainless steel was alloyed with niobium using double glow plasma surface alloying and tribological properties of Nb-alloyed steel such as hardness, friction and wear were measured. Effects of the alloying temperature on microstructure and the tribological behavior of the alloyed steel were investigated compared with untreated steel. Formation mechanisms of Nb-alloyed layers and increased wear resistance were also studied. The result shows that after surface Nb-alloying treatment, the 0.4C-13Cr steel exhibits a diffusion adhesion at the alloyed layer/substrate interface and improved tribological property. The friction coefficient of Nb-alloyed steel is decreased by about 0.3-0.45 and the wear rate after Nb-alloying is only 2-5% of untreated steel.

  17. Histidine side-chain dynamics and protonation monitored by C-13 CPMG NMR relaxation dispersion

    DEFF Research Database (Denmark)

    Hass, M. A. S.; Yilmaz, A.; Christensen, Hans Erik Mølager;

    2009-01-01

    The use of C-13 NMR relaxation dispersion experiments to monitor micro-millisecond fluctuations in the protonation states of histidine residues in proteins is investigated. To illustrate the approach, measurements on three specifically C-13 labeled histidine residues in plastocyanin (PCu) from...... Anabaena variabilis (A.v.) are presented. Significant Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion is observed for C-13(epsilon 1) nuclei in the histidine imidazole rings of A.v. PCu. The chemical shift changes obtained from the CPMG dispersion data are in good agreement with those obtained from...... states or other kinds of conformational changes of histidine side chains or their environment. Advantages and shortcomings of using the C-13(epsilon 1) dispersion experiments in combination with chemical shift titration experiments to obtain information on exchange dynamics of the histidine side chains...

  18. Isotopic studies of Yucca Mountain soil fluids and carbonate pedogenesis

    International Nuclear Information System (INIS)

    Secondary carbonates occurring within the soils, faults, and subsurface fractures of Yucca Mountain contain some of the best available records of paleoclimate and palehydrology for the potential radioactive waste repository site. This article discusses conceptual and analytical advances being made with regard to the interpretation of stable isotope data from pedogenic carbonates, specifically related to the 13C content of soil CO2, CaCO3, precipitation mechanisms, and isotopic fractionations between parent fluids and precipitating carbonates. The 13C content of soil carbon dioxide from Yucca Mountain and vicinity shows most of the usual patterns expected in such contexts: Decreasing 13C content with depth decreasing 13C with altitude and reduced 13C during spring. These patterns exist within the domain of a noisy data set; soil and vegetational heterogeneities, weather, and other factors apparently contribute to isotopic variability in the system. Several soil calcification mechanisms appear to be important, involving characteristic physical and chemical environments and isotopic fractionations. When CO2 loss from thin soil solutions is an important driving factor, carbonates may contain excess heavy isotopes, compared to equilibrium precipitation with soil fluids. When root calcification serves as a proton generator for plant absorption of soil nutrients, heavy isotope deficiencies are likely. Successive cycles of dissolution and reprecipitation mix and redistribute pedogenic carbonates, and tend to isotopically homogenize and equilibrate pedogenic carbonates with soil fluids

  19. Water stable isotopes: application to the water cycle and climate variations study

    International Nuclear Information System (INIS)

    The stable isotopic composition of water (H216, HDO, H218, H217) is a promising tracer of the present day water cycle and past climates. While the isotopic composition recorded in polar ice core have long been used to reconstruct past temperatures, however, what controls the isotopic composition of the tropical precipitation is more complex. The goal of this thesis is thus to better understand the processes that affect the isotopic composition of tropical precipitation and atmospheric water, more particularly in the tropics. Since most of the tropical precipitation arises from atmospheric convection, and most isotopic archives are on land, we focus more particularly on the impact of convective and land surface processes. In turn, what can be learned about convection and land surface processes using isotopic measurements? Can they help constrain their representation in models? At the inter-annual to climate change scale, what information about the tropical climate variability is recorded in isotopic signals observed in archives? First, we investigate the influence of convection on water stable isotopes. We use both (1) numerical modeling, with a hierarchy of models (single column model, two-dimensional model of squall lines, general circulation model) and (2) data analysis, using isotopic data from rain collected in the Sahel during the African Monsoon Multidisciplinary Analysis campaign, at the event and intra-event scales. These studies highlight the strong impact of convection on the precipitation composition, and stress the importance of rain evaporation and convective or meso-scale subsidence in controlling the rain isotopic composition. Convection also plays an important role on isotopic profiles in the upper troposphere-lower stratosphere. Second, we study what information about climatic variability is recorded by water stable isotopes in precipitation. We analyze simulations of present day and past climates with LMDZ, and evaluate to what extent isotopic

  20. Nuclear structure studies of rare francium isotopes using Collinear Resonance Ionization Spectroscopy (CRIS)

    CERN Document Server

    AUTHOR|(CDS)2084441

    It was known for many years that nuclei possessing certain numbers of protons (Z) and neutrons (N), called the magic numbers (8,20,28,50,82,126...), exhibit characteristic behavior and are in general more stable than their neighboring isotopes. As the capabilities of producing isotopes with more extreme values of Z and N increased, it was realized that those spherical nuclei only represent a small fraction of the total number of isotopes and that most isotopes are deformed. In order to study exotic isotopes and their deformation, it was necessary to develop new experimental techniques that would be powerful enough to be able to cope with very small production yields, but precise enough to measure the nuclear properties (such as radii and moments) with relatively small uncertainties. One technique that can measure nuclear properties of scarcely produced isotopes is in-source resonant ionization, but this technique does not allow for sufficient precision to deduce nuclear quadrupole moments. Furthermore, this t...

  1. The use of stable isotope tracers in the study of zinc and selenium nutrition in infants

    International Nuclear Information System (INIS)

    Two population groups potentially at risk of trace element deficiencies, pregnant women and infants (espe--cially pre-term infants) cannot be studied with in vivo radioactivity for trace elements nutrition. Another approach under development is the use of in vivo stable isotope tracers. A sample of the element in which a minor stable isotope is greatly enriched is administered and the element traced by observation of altered isotope ratios in blood (and its fractions), feces and urine. The altered isotope ratio can be observed by mass spectrometry or nuclear activation methods, with the latter being less susceptible to contamination by the normal element. With these techniques, gastrointestinal absorption of the isotopes can be determined. Calculations and experiments show that the most promising elements for stable isotope tracing with nuclear detection are Zn and Se, which play important roles in infant nutrition. (author)

  2. Structure of Li, Be And B isotopes studied with quantum molecular dynamic model

    International Nuclear Information System (INIS)

    Quantum molecular dynamics (QMD) is applied to study the ground state properties of Li, Be and B isotopes. The model Hamiltonian includes both two-and three-body density dependent interactions, a Coulomb term, and a momentum dependent Pauli potential. With parameters which guarantee the infinite nuclear matter properties, the QMD model can only reproduce the binding energies for Be and B isotopes. The experimental root mean square radii of the Li, Be and B isotopes are not sufficiently reproduced by these parameters. It is shown, however, that the binding energies and root mean square radii of these isotopes can simultaneously be reproduced in the lower density limit of the potential parameters

  3. Estimating Niche Width Using Stable Isotopes in the Face of Habitat Variability: A Modelling Case Study in the Marine Environment

    OpenAIRE

    David O Cummings; Jerome Buhl; Lee, Raymond W.; Stephen J Simpson; Sebastian P Holmes

    2012-01-01

    Distributions of stable isotopes have been used to infer an organism's trophic niche width, the 'isotopic niche', and examine resource partitioning. Spatial variation in the isotopic composition of prey may however confound the interpretation of isotopic signatures especially when foragers exploit resources across numerous locations. In this study the isotopic compositions from marine assemblages are modelled to determine the role of variation in the signature of prey items and the effect of ...

  4. Coordinated Isotopic and TEM Studies of Presolar Graphites from Murchison

    Science.gov (United States)

    Croat, T. K.; Stadermann, F. J.; Zinner, E.; Bernatowicz, T. J.

    2004-03-01

    TEM and NanoSIMS investigations of the same presolar Murchison KFC graphites revealed high Zr, Mo, and Ru content in refractory carbides within the graphites. Along with isotopically light carbon, these suggest a low-metallicity AGB source.

  5. Isotopic study of some fossil and actual hydrothermal systems

    International Nuclear Information System (INIS)

    Oxygen and hydrogen isotopic compositions of rocks from the INAG no 1 drillhole provide evidence of a fossil hydrothermal system in the Ceyssat region of the Massif Central. Oxygen isotope temperatures for the mineral paragenesis are about 2750C and the water is of marine origin. Measurements have also been made of delta13C values of dissolved carbon and gaseous CO2 from several hot springs in the Pyrenees and Massif Central. The carbon isotopic composition of the total systems have been calculated from the gas-liquid ratios at the emergence sites and these results are discussed in terms of the origin of the carbon. Most of the hydrothermal carbon is of deep origin. The observed variations in isotopic compositions may be explained by the behavior of the fluids during their ascent to the surface

  6. Triple Isotope Water Analyzer for Extraplanetary Studies Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Los Gatos Research (LGR) proposes to employ Off-Axis ICOS to develop triple-isotope water analyzers for lunar and other extraplanetary exploration. This instrument...

  7. Triple Isotope Water Analyzer for Extraplanetary Studies Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In this Small Business Innovative Research (SBIR) effort, Los Gatos Research (LGR) proposes to develop a miniature, high-resolution, low power, triple-isotope water...

  8. Fundamental studies in isotope chemistry. Progress report, 1 October 1980-1 August 1981

    International Nuclear Information System (INIS)

    The current program, as in the past, utilizes theoretical advances made specifically with respect to isotope chemistry in the study of the structure of matter. Experimental investigation using isotope effects provides a unique tool for the determination of the mean square force on an atom in a molecule and how it is affected by intermolecular forces. We have completed the systematic study of the isotope chemistry of hydrogen. Studies have been made of the isotopic reduced partition function ratio, (s/s')f, of thirty-nine diatomic and nineteen polyatomic hydrides. It encompasses compounds of hydrogen with every element in each row and each column of the periodic table. This progress report also includes a description of our final design for sampling a cryogenic liquid. Such a sampler is necessary if we are to realize the full potential of the isotopic fractionation method to study the mean square forces and torques in polyatomic liquids

  9. Estimation on soil erosion dynamics using stable isotope ratios of soil organic matter

    Science.gov (United States)

    Jakab, Gergely; Zacháry, Dóra; Szalai, Zoltán; Ringer, Marianna; Szabó, Judit

    2016-04-01

    Stable isotopes are a powerful and widely used tool for tracing biogeochemical processes across the ecosystem. Measuring the stable carbon, oxygen and hydrogen isotope composition of CO2 and H2O compounds and organic matter is useful for examining the soil, plant and atmospheric carbon and water pools as they isotopic composition is altered during vegetation-soil-atmosphere exchange processes (e.g., evapotranspiration, carbon assimilation and respiration). Stable carbon and nitrogen isotopes can serve as a tracer for C and N input by plants into the soil, C turnover and soil organic matter studies. In addition, coupling of isotopic tracers with molecular biology approaches and biomarkers can lead to a better understanding of the soil ecosystem processes. This study aims to estimate soil erosion deposition and redistribution processes at catena scale on the basis of stable isotope results. Soil samples were taken from the total depth of the solum along two catenas on an intensively tilled arable Cambisol. Highest δC13 values were found on the most eroded spots, while on the deposition areas significant differences were measured among the sedimented layers. The lowest δC13 value was in the buried horizon at around 120 cm depth. From this horizon δC13 values slightly increased in both upward and downward directions. However the total organic carbon concentration was highly fluctuated in the deposited profiles and have not reached its maximum in this horizon isotope results suggest that this horizon could have been the original soil surface prior to the main erosion events. In this way the use of stable isotope changes in space can provide additional information on soil redistribution due to tillage erosion. National Hungarian Research Found K100180, G. Jakab was supported by the János Bolyai fellowship of the HAS.

  10. Use of micrometeorological techniques to study the isotopic exchange in ecosystems

    Science.gov (United States)

    Santos, E.; Wagner-Riddle, C.; Brown, S. E.; Stropes, K.

    2015-12-01

    The combination of micrometeorological techniques with high frequency concentration measurements of stable isotopes are a powerful tool to study the temporal dynamics of isotope signatures at the ecosystem level. The objective of this study was to study the isotopic composition of the net CO2 exchange (NEE) above and with corn and tall grass canopies. Profiles of stable isotopes of CO2 (12C-CO2, 13C-CO2 and 18O-CO2) were measured using tunable diode laser trace gas analyzers and multiport sampling systems in corn (12C-CO2 and 13C-CO2, only) and tall grass canopies. These measurements were combined with the flux gradient method and Lagrangian dispersion analysis to estimate the isotopic signatures of the net CO2 flux. The use of a gradient of a concentration threshold to screen half hourly period improved the estimates of flux signatures by the isotope flux ratio approach. The Langrangian dispersion analysis and the isotope flux ratio method estimates showed good agreement above the corn canopy, indicating that the former method can be a viable alternative to study the isotopic exchange within plant canopies. The 13CO2 composition of NEE showed a downward trend near the end of the growing season, which may be related to a reduction of autotrophic respiration in the soil.

  11. Contribution of stable isotopes to the study of pharmacokinetics of magnesium salts

    International Nuclear Information System (INIS)

    The use of stable isotopes as labels is becoming an attractive tool for the study of magnesium behavior in humans. It has been used two stable isotopes of magnesium, 25Mg and 26Mg, to measure the absolute bioavailability of a pharmaceutical form of magnesium. (N.C.)

  12. Stable isotope studies. Progress report, August 1, 1974--July 31, 1975

    International Nuclear Information System (INIS)

    Progress is reported in the following studies: selective two-step laser-induced photodissociation, unimolecular processes induced by multiple-photon absorption, and vibrational energy transfer processes involving isotopic species of sulfur dioxide. These laser-induced chemical reactions can possibly be applied to isotope separation

  13. Advisory group meeting on stable isotope labelled compounds in biomedical studies

    International Nuclear Information System (INIS)

    The programme of the meeting was restricted to topics involving applications of stable isotopes of the lighter elements (H, C, N, O). The current status of stable isotope techniques and applications in nutritional and biomedical studies, the applicability of these techniques in developing countries and the IAEA's future programmes on this topic were discussed

  14. On depth profiling of hydrogen and helium isotopes and its application to ion-implantation studies

    International Nuclear Information System (INIS)

    The thesis is divided into two parts, the first being a general review of the experimental methods for depth profiling of light isotopes, where ion beams are used. In the second part, studies of ion implantation of hydrogen and helium isotopes, applying the techniques discussed in the first part, are described. The paper summarizes recent experimental results and discusses recent developments. (Auth.)

  15. Carbon and oxygen isotope study of carbonates from highly shocked clasts of the polymict breccia of the Haughton Crater (Canada)

    Science.gov (United States)

    Agrinier, P.; Martinez, I.; Javoy, M.; Schaerer, U.

    1992-01-01

    It is known that the release of volatiles on impact is an important controlling factor in cratering processes in carbonate terranes and in the mobility of chemical elements. In order to assess the nature and the role of carbon- and oxygen-bearing volatiles during impact-induced metamorphism of sedimentary rocks, the C-13/C-12 and O-18/O-16 ratios and carbonate contents were determined for 30 shocked clasts from the Haughton Crater polymict breccia as well as for some unshocked carbonates from the sedimentary cover adjacent to the crater. Shock-induced CO2 loss during decarbonation of calcite is known to be a function of peak pressure and ambient partial pressure of the volatile species. In our clast samples, shocked from 20 to 60 GPa, we expect about 20 to 100 percent CO2 loss and preferential depletion in C-13 and O-18 in the residual carbonate. Rayleigh model (progressive loss of CO2) and batch model (single-step loss of CO2) curves for this depletion are shown. The magnitudes of the C-13 and O-18 depletions increase with the increase of the CO2 loss. In addition, the isotopic depletions should be correlated with an enrichment in CaO and MgO in the residual solid.

  16. Isotopic studies of Yucca Mountain soil fluids and carbonate pedogenesis

    International Nuclear Information System (INIS)

    Secondary carbonates occurring within the soils, faults, and subsurface fractures of Yucca Mountain contain some of the best available records of paleoclimate and paleohydrology for the potential radioactive waste repository site. This article discusses conceptual and analytical advances being made with regard to the interpretation of stable isotope data from pedogenic carbonates, specifically related to the 13C content of soil CO2, CaCO3 precipitation mechanisms, and isotopic fractionations between parent fluids and precipitating carbonates. The 13C content of soil carbon dioxide from Yucca Mountain and vicinity shows most of the usual patterns expected in such contexts: decreasing 13C content with depth (due mainly to increased importance of respired CO2), decreasing 13C with altitude (partially due to relatively more C-3 vegetation), and reduced 13C during spring (due again to higher rates of respiration, and reduced gas permeability of wet soils). These patterns exist within the domain of a noisy data set; soil and vegetational heterogeneities, weather, and other factors apparently contribute to isotopic variability in the system. Several soil calcification mechanisms appear to be important, involving characteristic physical and chemical environments and isotopic fractionations. When CO2 loss from thin soil solutions is an important driving factor, carbonates may contain excess heavy isotopes, compared to equilibrium precipitation with soil fluids. When root calcification serves as a proton generator for plant absorption of soil nutrients, heavy isotope deficiencies are likely. Successive cycles of dissolution and reprecipitation mix and redistribute pedogenic carbonates, and tend to isotopically homogenize and equilibrate pedogenic carbonates with soil fluids

  17. Groundwater pollution studies in Lahore urban area - isotope hydrochemical approach

    International Nuclear Information System (INIS)

    Present study was undertaken to assess the levels and sources of groundwater pollution in Lahore aquifer. Water samples collected on periodical basis from existing hand pumps, tube wells and drains were analyzed for chemical constituents (Na, K, Ca, Mg, Fe, Cl, HCO/sub 3/, CO/sub 3/, NO/sub 3/, SO/sub 4/). Selected samples were analyzed for isotopic composition (C/sup 13/, N/sup 15/) and Coliform bacteria also. The data show that quality of groundwater has significantly deteriorated at most of the locations and concentrations of several parameters are higher than WHO criteria of good quality drinking water. An increase in nitrate concentrations especially in shallow groundwater (10 to 188 mg/l) was noted. Highly enriched delta N/sup 15/ values of high nitrate water samples (+10.3 to +25.1%) indicate that nitrates are derived from domestic wastes thrown into sewage drains. Penetration of polluted water from sewerage drains was also confirmed on the basis of delta C/sup 13/ and Fecal Coliform data (0-26 coliform/100 ml of sample). (author)

  18. Feasibility study of medical isotope production at Sandia National Laboratories

    International Nuclear Information System (INIS)

    In late 1994, Sandia National Laboratories in Albuquerque, New Mexico, (SNL/NM), was instructed by the Department of Energy (DOE) Isotope Production and Distribution Program (IPDP) to examine the feasibility of producing medically useful radioisotopes using the Annular Core Research Reactor (ACRR) and the Hot Cell Facility (HCF). Los Alamos National Laboratory (LANL) would be expected to supply the targets to be irradiated in the ACRR. The intent of DOE would be to provide a capability to satisfy the North American health care system demand for 99Mo, the parent of 99mTc, in the event of an interruption in the current Canadian supply. 99mTc is used in 70 to 80% of all nuclear medicine procedures in the US. The goal of the SNL/NM study effort is to determine the physical plant capability, infrastructure, and staffing necessary to meet the North American need for 99Mo and to identify and examine all issues with potential for environmental impact

  19. Isotope studies to assess water development in mining dump sites

    International Nuclear Information System (INIS)

    After the ending of the lignite exploitation open mining pits with dump sites of heterogeneous mixture of Tertiary and Quaternary sediments were flooded by groundwater and river water inflow forming partially acidic (pH about 2 to 3) mining lakes with high sulphate (>3000 mg/L) and iron content (>500 mg/L) (Friese et al., 1998). The renewing of the groundwater system in mining areas is a very complicated process. The knowledge of the whole as well as of parts of that process is important for the future water management and for land use. Acidification of surface and groundwater based on pyrite oxidation dominates water quality development of the groundwater and of the flooded pits. The different sulphur compounds and the distribution of sulphur sources (pyrite, sulphate, sulphide) can easily controlled by the sulphur and oxygen isotope analyses. Our studies are focused on an acidic mine lake ML 111 in the Lusatian Lignite District and on the Cospuden lignite mine south of Leipzig

  20. Feasibility study of medical isotope production at Sandia National Laboratories

    Energy Technology Data Exchange (ETDEWEB)

    Massey, C.D.; Miller, D.L.; Carson, S.D. [Sandia National Labs., Albuquerque, NM (United States). Environmental Regulatory Assessment Dept.] [and others

    1995-12-01

    In late 1994, Sandia National Laboratories in Albuquerque, New Mexico, (SNL/NM), was instructed by the Department of Energy (DOE) Isotope Production and Distribution Program (IPDP) to examine the feasibility of producing medically useful radioisotopes using the Annular Core Research Reactor (ACRR) and the Hot Cell Facility (HCF). Los Alamos National Laboratory (LANL) would be expected to supply the targets to be irradiated in the ACRR. The intent of DOE would be to provide a capability to satisfy the North American health care system demand for {sup 99}Mo, the parent of {sup 99m}Tc, in the event of an interruption in the current Canadian supply. {sup 99m}Tc is used in 70 to 80% of all nuclear medicine procedures in the US. The goal of the SNL/NM study effort is to determine the physical plant capability, infrastructure, and staffing necessary to meet the North American need for {sup 99}Mo and to identify and examine all issues with potential for environmental impact.

  1. NMR studies of two spliced leader RNAs using isotope labeling

    Energy Technology Data Exchange (ETDEWEB)

    Lapham, J.; Crothers, D.M. [Yale Univ., New Haven, CT (United States)

    1994-12-01

    Spliced leader RNAs are a class of RNA molecules (<200 nts) involved in the trans splicing of messenger RNA found in trypanosomes, nematodes, and other lower eukaryotes. The spliced leader RNA from the trypanosome Leptomonas Collosoma exists in two alternate structural forms with similar thermal stabilities. The 54 nucleotides on the 5{prime} end of the SL molecule is structurally independent from the 3{prime} half of the RNA, and displays the two structural forms. Furthermore, the favored of the two structures was shown to contain anomalous nuclease sensitivity and thermal stability features, which suggests that there may be tertiary interactions between the splice site and other nucleotides in the 5{prime} end. Multidimensional NMR studies are underway to elucidate the structural elements present in the SL RNAs that give rise to their physical properties. Two spliced leader sequences have been studied. The first, the 54 nucleotides on the 5{prime} end of the L. Collosoma sequence, was selected because of earlier studies in our laboratory. The second sequence is the 5{prime} end of the trypanosome Crithidia Fasciculata, which was chosen because of its greater sequence homology to other SL sequences. Given the complexity of the NMR spectra for RNA molecules of this size, we have incorporated {sup 15}N/{sup 13}C-labeled nucleotides into the RNA. One of the techniques we have developed to simplify the spectra of these RNA molecules is isotope labeling of specific regions of the RNA. This has been especially helpful in assigning the secondary structure of molecules that may be able to adopt multiple conformations. Using this technique one can examine a part of the molecule without spectral interference from the unlabeled portion. We hope this approach will promote an avenue for studying the structure of larger RNAs in their native surroundings.

  2. Stable isotope ratio measurements in atmospheric sulfate studies

    International Nuclear Information System (INIS)

    The isotopic composition of atmospheric sulfate has been determined by a number of workers and the results interpreted in terms of contributing sources and mechanisms of origin. A correlation between the 18O enrichment of atmospheric water and airborne particulate sulfate has been observed. Laboratory preparations of sulfate made from sulfur dioxide by two sets of sequential reactions, hydrolysis followed by oxidation and oxidation followed by hydrolysis, yielded products of distinguishable oxygen-isotope composition. Oxygen isotopic analysis of simultaneously collected field samples of ambient sulfate, sulfur dioxide, and water vapor indicated seasonal trends for all of the major constituents of atmospheric sulfation processes. Some isotopic data were also obtained on precipitation and precipitation sulfates. Field results suggest that ambient sulfates collected in the area of Argonne correpond more closely in oxygen isotope composition to a sulfate molecule containing two oxygens originating from sulfur dioxide, one oxygen from air and one oxygen from condensed-phased atmospheric water, SO/sub s/O/sub s/O/sub cw/O2-/sub a/, than to the molecule SO/sub s/O/sub s/O/sub wv/O2/sub a/ in which one oxygen originates from vapor-phase atmospheric water

  3. Stable isotope ratio measurements in atmospheric sulphate studies

    International Nuclear Information System (INIS)

    The isotopic composition of atmospheric sulphate has been determined by a number of workers and the results interpreted in terms of contributing sources and mechanisms of origin. A correlation between the 18O enrichment of atmospheric water airborne particulate sulphate has been observed. Laboratory preparations of sulphate made from sulphur dioxide by two sets of sequential reactions, (1) hydrolysis followed by oxidation and (2) oxidation followed by hydrolysis, yielded products of distinguishable oxygen-isotope composition. Oxygen isotopic analysis of simultaneously collected field samples of ambient sulphate, sulphur dioxide, and water vapour indicated seasonal trends for all of the major constituents of atmospheric sulphation processes. Some isotopic data were also obtained on precipitation and precipitation sulphates. Field results suggest that ambient sulphates collected in the area of Argonne correspond more closely in oxygen isotope composition to a sulphate molecule containing two oxygens originating from sulphur dioxide, one oxygen from air and one oxygen from condensed-phase atmospheric water than to the molecule in which one oxygen originates from vapourphase atmospheric water. (author)

  4. Sr isotopic tracer study of the Samail ophiolite, Oman

    International Nuclear Information System (INIS)

    We have measured Rb and Sr concentrations and Sr isotopic compositions in 41 whole-rock samples and 12 mineral separates from units of the Samail ophiolite, including peridotite, gabbro, plagiogranite diabase dikes, and gabbro and websterite dikes within the metamorphic peridotite. Ten samples of cummulate gabbro from the Wadir Kadir section and nine samples from the Wadi Khafifah section have mean 87Sr/86Sr ratios and standard deviations of 0.70314 +- 0.00030 and 0.70306 +- 0.00034, respectively. The dispersion in Sr isotopic composition may reflect real heterogeneities in the magma source region. The average Sr isotopic composition of cumulate gabbro falls in the range of isotopic compositions of modern midocean ridge basalt. The 87Sr/86Sr ratios of noncumulate gabbro, plagiogranite, and diabase dikes range from 0.7034 to 0.7047, 0.7038 to 0.7046, and 0.7037 to 0.7061, respectively. These higher 87Sr/86Sr ratios are due to alteration of initial magmatic compositions by hydrothermal exchange with seawater. Mineral separates from dikes that cut harzburgite tectonite have Sr isotopic compositions which agree with that of cumulate gabbro. These data indicate that the cumulate gabbro and the different dikes were derived from partial melting of source regions that had similar long-term histories and chemical compositions

  5. Budding yeast cDNA sequencing project: S03036-24_C13 [Budding yeast cDNA sequencing project

    Lifescience Database Archive (English)

    Full Text Available S03036-24_C 13 - - - Show S03036-24_C 13 Seqid S03036-24_C 13 Link to SGD - Link to dbEST - Link to ... UC SC ... Genome Browser - Sequenc e >S03036-24_C 13.phd NNN ... NNNNNNNNNNNNNNANNNNNNNNTGNNGGNNNNNTNNNNNN ANTTGNTATC GAC TTNNTTCC NNNNGAGANNNNNNTGGANAANGANGAGNNNNNGNANAC ... TTNNGANAAANANNC NNANGGTGAGAGCC AGATCC NNNNNNGC GGATTGNGAGC AAATC G TTAAG ... TTC AGGTC AAGTAAAAATTGATTTC NAAAAC TAATTTC TC TTATAC NANNNTTT ...

  6. Application of carbon and oxygen stable isotopes to the study of Brazilian precambrian

    International Nuclear Information System (INIS)

    Samples of carbonated rocks of precambrian age are studied. The stable carbon and oxygen isotopes are applied to the study of terrestrial materials considering the variations of some element isotopic composition in function of the environment of sedimentation. The isotopic analysis was done using mass spectrometers. The analytical results and the description of region geology of the site of each sample are presented. The isotopic data are interpreted aiming to the environment of sedimentation. New techniques for better improvement of carbon and oxygen ratios, are proposed, such as: to use the analysis of surface trend and the isotopic logging in mapping of surface and subsurface. A new method for approximated determination of the ages of precambrian carbonated rocks, considering the limitations of their new technique, is also presented. (M.C.K.)

  7. Study of hyperfine anomaly in 9,11Be isotopes

    International Nuclear Information System (INIS)

    The study of the hyperfine anomaly of neutron rich nuclei, in particular, neutron halo nuclei, can give a very specific and unique way to measure their neutron distribution and confirm a halo structure. The hyperfine structure anomaly in Be+ ions is calculated with a realistic electronic wave function, obtained as a solution of the Dirac equation. In the calculations, the Coulomb potential modified by the charge distribution of the clustered nucleus and three electrons in the configuration 1s22s is used. The nuclear wave function for the 11Be nucleus is obtained in the core + nucleon model, and that for the 9Be nucleus is calculated in the three-cluster (α+α + n) model. The aim of this study is to test whether the hyperfine structure anomaly reflects an extended spatial structure of '11Be. The results of the calculations are listed. εBW is the hyperfine anomaly in the Bohr-Weisskopf effect and δ is the charge structure correction, μ is the calculated magnetic moment, and μexp is the experimental value of the magnetic moment, Q and Qexp are the calculated and measured values of the quadrupole moment. The results for 9Be are obtained with two different three-body wave functions (WF1 and WF2) showing the sensitivity of the calculations to the input parameters. The value of εBW is sensitive to the weights of the states in the nuclear ground state wave function. The total hyperfine anomaly value εεBW +δ in 11Be differs from that in 9Be by 25%. This gives a measure of the accuracy of the hyperfine anomaly measurements needed to study the neutron distribution in the Be isotopes. (authors)

  8. Isotope pattern deconvolution as a tool to study iron metabolism in plants

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Castrillon, Jose A.; Moldovan, Mariella; Garcia Alonso, J.I. [University of Oviedo, Department of Physical and Analytical Chemistry, Oviedo (Spain); Lucena, Juan J.; Garcia-Tome, Maria L.; Hernandez-Apaolaza, Lourdes [Autonoma University of Madrid, Department of Agricultural Chemistry, Madrid (Spain)

    2008-01-15

    Isotope pattern deconvolution is a mathematical technique for isolating distinct isotope signatures from mixtures of natural abundance and enriched tracers. In iron metabolism studies measurement of all four isotopes of the element by high-resolution multicollector or collision cell ICP-MS allows the determination of the tracer/tracee ratio with simultaneous internal mass bias correction and lower uncertainties. This technique was applied here for the first time to study iron uptake by cucumber plants using {sup 57}Fe-enriched iron chelates of the o,o and o,p isomers of ethylenediaminedi(o-hydroxyphenylacetic) acid (EDDHA) and ethylenediamine tetraacetic acid (EDTA). Samples of root, stem, leaves, and xylem sap, after exposure of the cucumber plants to the mentioned {sup 57}Fe chelates, were collected, dried, and digested using nitric acid. The isotopic composition of iron in the samples was measured by ICP-MS using a high-resolution multicollector instrument. Mass bias correction was computed using both a natural abundance iron standard and by internal correction using isotope pattern deconvolution. It was observed that, for plants with low {sup 57}Fe enrichment, isotope pattern deconvolution provided lower tracer/tracee ratio uncertainties than the traditional method applying external mass bias correction. The total amount of the element in the plants was determined by isotope dilution analysis, using a collision cell quadrupole ICP-MS instrument, after addition of {sup 57}Fe or natural abundance Fe in a known amount which depended on the isotopic composition of the sample. (orig.)

  9. C-13 NMR spectroscopy of plasma reduces interference of hypertriglyceridemia in the H-1 NMR detection of malignancy; Application in patients with breast lesions

    Energy Technology Data Exchange (ETDEWEB)

    Fossell, E.T.; Hall, F.M. (Beth Israel Hospital and Harvard Medical School, Charles E. Dana Research Institute, Boston (USA). Department of Radiology); McDonagh, J. (Beth Israel Hospital and Harvard Medical School, Charles E. Dana Research Institute, Boston (USA). Department of Pathology)

    1991-05-01

    The authors have previously described the application of water-suppressed proton nuclear magnetic resonance (H-1 NMR) spectroscopy of plasma for detection of malignancy. Subsequently, hypertriglyceridemia has been identified as a source of false positive results. Here is described a confirmatory, adjunctive technique -analysis of the carbon-13 (C-13) NMR spectrum of plasma- which also identifies the presence of malignancy but is not sensitive to the plasma triglyceride level. Blinded plasma samples from 480 normal donors and 208 patients scheduled for breast biopsy were analyzed by water-suppressed H-1 and C-13 NMR spectroscopy. Triglyceride levels were also measured. Among the normal donors, there were 38 individuals with hypertriglyceridemia of whom 18 had results consistent with malignancy by H-1 NMR spectroscopy. However, the C-13 technique reduced the apparent H-1 false positive rate from 7.0 to 0.6 percent. Similarly, in the breast biopsy cohort, C-13 reduced the false positive rate from 2.8 to 0.9 percent. Furthermore, the accuracy of the combined H-1/C-13 test in this blinded study was greater than 96 percent in 208 patients studied. (author). 27 refs.; 5 figs.; 4 tabs.

  10. Isotope correlation studies relative to high enrichment test reactor fuels

    International Nuclear Information System (INIS)

    Several correlations of fission product isotopic ratios with atom percent fission and neutron flux, for highly enriched 235U fuel irradiated in two different water moderated thermal reactors, have been evaluated. In general, excellent correlations were indicated for samples irradiated in the same neutron spectrum; however, significant differences in the correlations were noted with the change in neutron spectrum. For highly enriched 235U fuel, the correlation of the isotopic ratio 143Nd/145+146Nd with atom percent fission has wider applicability than the other fission product isotopic ratio evaluated. The 137Cs/135Cs atom ratio shows promise for correlation with neutron flux. Correlations involving heavy element ratios are very sensitive to the neutron spectrum

  11. Experimental stand for studies of hydrogen isotopes permeation

    International Nuclear Information System (INIS)

    As a result of the high probability of hydrogen isotope permeation through materials used in high-temperature reactor operations, the interaction of hydrogen isotopes with metallic structural materials proposed to be used for fusion reactor designing is of great importance for safety considerations. Determining the parameters of the interaction between hydrogen isotopes and different materials, is therefore essential to accurately calculate recycling, outgassing, loading, permeation and hydrogen embrittlement. The permeation tests were made in collaboration with IFIN Bucuresti inside of a special glove-box to avail their radioactive protection expertise. This investigation programme is ongoing. In this paper we describe the permeation stand facility and the preliminary tests carried out to date. (authors)

  12. Carbon isotopic studies of organic matter in Precambrian rocks.

    Science.gov (United States)

    Oehler, D. Z.; Schopf, J. W.; Kvenvolden, K. A.

    1972-01-01

    A survey has been undertaken of the carbon composition of the total organic fraction of a suite of Precambrian sediments to detect isotopic trends possibly correlative with early evolutionary events. Early Precambrian cherts of the Fig Tree and upper and middle Onverwacht groups of South Africa were examined for this purpose. Reduced carbon in these cherts was found to be isotopically similar to photosynthetically produced organic matter of younger geological age. Reduced carbon in lower Onverwacht cherts was found to be anomalously heavy; it is suggested that this discontinuity may reflect a major event in biological evolution.

  13. Design study of fuel circulating system using Pd-alloy membrane isotope separation method

    International Nuclear Information System (INIS)

    Design study on the fuel circulating system (FCS) for a tokamak experimental fusion reactor (JXFR) has been carried out to establish the system concept, to plan the development program, and to evaluate the feasibility of diffusion system. The FCS consists of main vacuum system, fuel gas refiners, isotope separators, fuel feeders, and auxiliary systems. In the system design, Pd-alloy membrane permeation method is adopted for fuel refining and isotope separating. All impurities are effectively removed and hydrogen isotopes are sufficiently separated by Pd-alloy membrane. The isotope separation system consists of 1st (47 separators) and 2nd (46 separators) cascades for removing protium and separating deuterium, respectively. In the FCS, while cryogenic distillation method appears to be practicable, Pd-alloy membrane diffusion method is attractive for isotope separation and refining of fuel gas. The choice will have to be based on reliability, economic, and safety analyses

  14. Depletion of 13C in lignin and its implications for stable carbon isotope studies

    International Nuclear Information System (INIS)

    Stable carbon isotope compositions of organic matter are now widely used to trace carbon flow in ecosystems, and have been instrumental in shaping current perceptions of the importance of terrestrial vegetation to estuarine and coastal marine environments. A general assumption in these and other studies relying on carbon isotope compositions for source identification of organic matter has been that the major biochemical components of plant tissues are isotopically invariant. We report here large differences between the carbon isotope compositions of the polysaccharide and lignin components of a variety of vascular plants, including the salt-marsh grass Spartina alterniflora, and demonstrate that the carbon isotope composition of Spartina detritus gradually changes during biogeochemical processing as polysaccharides are preferentially removed, leaving a material that is relatively enriched in lignin-derived carbon and depleted in 13C. (author)

  15. Experimental Study of Silicon Isotope Dynamic Fractionation and Its Application in Geology

    Institute of Scientific and Technical Information of China (English)

    李延河; 丁悌平; 等

    1995-01-01

    Silicon shows no vatiation in its chemical valence in nature and exists mainly in the form of silicon-oxygen tetrahedra,so very small silicon isotope thermodynamic frac-tionation occurs and the resultant silicon isotope variation is limited.Dynamic fraction-ation of Si isotopes during precipitation of SiO2 from a solution is a main factor leading to substantial variations in silicon isotopes in nature. In this experimental study,we determined the dynamic fractionation factor αfor silicon isotopes during precipitation of SiO2 from the solution.And in combination of α, a theoretical explanation is pre-sented of the considerably low &30Si values of black smokers on modern seafloor ,Archean banded magnetite-quartzite and clay minerals of weathering origin ,and of clearly high &30Si values of siliceous rocks in shallow -sea carbonate platforms.

  16. Stable-isotope studies. Progress report, March 1, 1980-August 25, 1982

    International Nuclear Information System (INIS)

    Investigations during the past two-and-a half year priod have been directed toward the following three areas: (1) studies of vapor pressure isotope effects (fluoroform, methyl fluoride, methylene difluorides, ammonia); (2) studies on the fractionation of nitrogen isotope systems; and (3) theory of isotope effect. Studies on the fractionation of nitrogen isotope fractionaton systems involved two fronts. One is a study of 15N-production by means of a countercurrent isotope exchange in a packed column between a gas phase, which is a mixture of various NO/sub x/, and a liquid phase, which is mainly N2O3 and N2O4. The second deals with a concept of closed reflux cycle for the Nitrox and/or the NO/N2O3-process. In the theoretical field, studies of isotopic reduced partition function ratio has led to revelations of interesting correlations between molecular structures, molecular forces, and the isotope effects. The investigations for this period are summarized and a more thorough discussion is presented for each ongoing research

  17. C-13 NMR characterization of humic materials isolated by an MIBK partitioning procedure

    International Nuclear Information System (INIS)

    The organic matter from a peat and a stream sediment was fractionated into fulvic acid, humic acid, and humin using a previously reported MIBK (methylisobutyl ketone) partitioning procedure. The bulk stream sediment was collected from the north fork of Clear Creek, Gilpin County, Colorado. The north fork of Clear Creek has its headwaters in the bogs located on Guanella Pass, Gilpin County, Colorado. The peat sample was collected from a boggy soil, classified as a Cryohemist, on Guanella Pass. This work presents the solution state C-13 NMR spectra of humic materials isolated by a unique variation of the traditional method for extracting humus from a soil or peat and finds them typical of humic and fulvic acids. The C-13 NMR spectrum of the humin-humic acid, obtained by disaggregating humin through an extension of this method shows it to be very similar to the C-13 NMR spectrum of the corresponding humic acid recorded under identical conditions. (Auth.)

  18. Stable Isotope Studies of Crop Carbon and Water Relations: A Review

    Institute of Scientific and Technical Information of China (English)

    ZHANG Cong-zhi; ZHANG Jia-bao; ZHAO Bing-zi; ZHANG Hui; HUANG Ping

    2009-01-01

    Crop carbon and water relations research is important in the studies of water saving agriculture,breeding program,and energy and material cycles in soil plant atmosphere continuum (SPAC).The purpose of this paper is to review the current state of knowledge on stable isotopes of carbon,oxygen,and hydrogen in the research of crop carbon and water relations,such as carbon isotope discrimination (△13C) during carbon fixation process by photosynthesis,application of △13C in crop water use efficiency (WUE) and breeding programs,oxygen isotope enrichment during leaf water transpiration,CO2 fixation by photosynthesis and release by respiration,application of hydrogen isotope composition (δD) and oxygen isotope composition (δ18O) for determination of water source used by a crop,stable isotope coupling Keeling plot for investigating the carbon and water flux in ecosystem,energy and material cycle in SPAC and correlative integrative models on stable isotope.These aspects contain most of the stable isotope researches on crop carbon and water relations which have been widely explored internationally while less referred in China.Based on the reviewed literatures,some needs for future research are suggested.

  19. Contribution of stable isotopes to the study of pharmacokinetics of magnesium salts; Apport des isotopes stables a l'etude de la pharmacocinetique de sels de magnesium

    Energy Technology Data Exchange (ETDEWEB)

    Benech, H

    1999-05-28

    The use of stable isotopes as labels is becoming an attractive tool for the study of magnesium behavior in humans. It has been used two stable isotopes of magnesium, {sup 25}Mg and {sup 26}Mg, to measure the absolute bioavailability of a pharmaceutical form of magnesium. (N.C.)

  20. High flux isotope reactor cold source preconceptual design study report

    International Nuclear Information System (INIS)

    In February 1995, the deputy director of Oak Ridge National Laboratory (ORNL) formed a group to examine the need for upgrades to the High Flux Isotope Reactor (HFIR) system in light of the cancellation of the Advanced Neutron Source Project. One of the major findings of this study was that there was an immediate need for the installation of a cold neutron source facility in the HFIR complex. The anticipated cold source will consist of a cryogenic LH2 moderator plug, a cryogenic pump system, a refrigerator that uses helium gas as a refrigerant, a heat exchanger to interface the refrigerant with the hydrogen loop, liquid hydrogen transfer lines, a gas handling system that includes vacuum lines, and an instrumentation and control system to provide constant system status monitoring and to maintain system stability. The scope of this project includes the development, design, safety analysis, procurement/fabrication, testing, and installation of all of the components necessary to produce a working cold source within an existing HFIR beam tube. This project will also include those activities necessary to transport the cold neutron beam to the front face of the present HFIR beam room. The cold source project has been divided into four phases: (1) preconceptual, (2) conceptual design and research and development (R and D), (3) detailed design and procurement, and (4) installation and operation. This report marks the conclusion of the preconceptual phase and establishes the concept feasibility. The information presented includes the project scope, the preliminary design requirements, the preliminary cost and schedule, the preliminary performance data, and an outline of the various plans for completing the project

  1. Development of a Laser Probe for Argon Isotope Studies.

    Science.gov (United States)

    McConville, Paul

    Available from UMI in association with The British Library. The first objective of this study was to develop a laser outgassing facility for argon isotope studies. Apart from the laser and construction of the laser sample port, existing vacuum and mass spectrometer systems were used. Laser performance and optimum operating conditions were investigated. The second objective was test and evaluate the laser extraction technique by studies of simple geological samples. Previous laser ^{40} Ar-^{39}Ar dating studies by other workers had not systematically established the basis or characteristics of the method. Results from laser and complementary stepped heating studies of the ^{40}Ar-^ {39}Ar dating standard hornblende, hb3gr; a phlogopite sample from the Palabora (Phalaborwa) Complex; and biotites in a thin section of the Hamlet Bjerg granite from East Greenland, verified that: (1) Laser extraction reproduced within experimental error the stepped heating ^{40}Ar-^ {39}Ar and K-Ar ages of simple samples. (2) The precision of the technique i.e. the amount of sample required to give reliable ages, was limited in the present experiments largely by the level of the blanks and backgrounds to 10-100 ug samples. (3) Sample outgassing appeared to be limited to the order of 10 um outside the physical size of the laser pit, consistent with other estimates of the spatial definition in the literature. This could be understood by thermal diffusion and the length of the laser pulse. (4) The efficiency of the laser pulse in melting and outgassing mineral samples was shown to be dependent on silicate latent heats and mineral absorption at the laser wavelength. In addition, the ^{40} Ar-^{39}Ar age of the geologically significant Palabora Complex was determined as (2053 +/- 5) Ma. Excess argon led to a discrepancy between the laser and stepped heating ages of biotite and muscovite, (405 +/- 5) Ma, and laser ages of feldspars (510 +/- 20) Ma in the Hamlet Bjerg granite. This illustrated

  2. Environmental isotope studies of marine coastal pollution in Pakistan

    International Nuclear Information System (INIS)

    The International Atomic Energy Agency (the Agency), Vienna launched a five year (duration: 1998 - 2002) Joint Project on 'Better Management of the Environment and Industrial Growth Through Isotopes and Radiation Technology (RAS/97/030) in co-operation with the RCA (Regional Co-operative Agreement) office-Vienna, and UNDP (United Nations Development Programme). The Marine Sub-project entitled 'Management of Marine Coastal Environment and its Pollution (RAS/8/083)' is a key component of this joint project. Pakistan has significantly contributed in the marine sub-project by demonstrating the potential use of environmental isotope techniques such as stable isotope ratios of oxygen-18 in water molecules, carbon-13 in total dissolved inorganic carbon (TDIC), carbon-13 in total dissolved inorganic carbon as well as marine plant (leaves and tree rings), nitrogen-15 in marine plants and animal shells, and sulfur-34 in aqueous sulfate for tracking the transport of pollutants in marine coastal environment. This paper/poster highlights the innovative use of these environmental stable isotope techniques in relation to conventional physiochemical techniques for tracking fate and behaviour of land based domestic / industrial pollution inventory in the marine coastal environment of Pakistan

  3. Hydrologic and isotopic study of the Quito aquifer

    International Nuclear Information System (INIS)

    The dynamics of the Quito basin and surrounding area aquifers were determined through the use of stable and radioactive isotopes, and the monitoring of the freatic levels and of the bacteriological and physico-chemical quality of the water. A conceptual hydrodynamic model of the Quito aquifer was also proposed in order to establish in the future a sustainable management system

  4. Pb isotopic geochemical study on the crustal structure of Tongbaishan

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Pb isotopic composition of the Tongbai complex, distributed in the Tongbaishan to the west of the Dabieshan, ranges between the Dabie core complex and the Dabie ultral-high pressure (UHP) metamorphic complex, the latter having more radiogenic Pb isotopic composition than the former. Granites from the Jigongshan pluton, which intruded mainly into the Tongbai complex, are distinct from the Tongbai complex but similar to the Dabie core complex in Pb isotopic composition, showing that the magma of the Jigongshan granites was derived from the partial melting of the Dabie core complex. According to Pb isotopic compositional variation model in the vertical crustal section and magma source from the Jigongshan pluton, it is suggested that the Tongbai complex was an upper rock serial of the Dabie core complex, which is beneath the Dabie UHP metamorphic complex in the crustal structure of the Tongbai-Dabie orogenic belt. The Tongbai complex was not well preserved in the Dabie area due to the high exhumed crustal section. However, the crustal section in the Tongbai area was exhumed less than that in the Dabie area, and the deep crust in the Tongbai area still contains the basement composition similar to the Dabie core complex. Therefore, the crustal basements from the Dabie to Tongbai areas are united. The present distribution of the basement blocks in different locations of the Tongbai-Dabie orogenic belt reflects different exposure of the crustal section.

  5. Growth of adlayers studied by fluorination of isotopically engineered graphene

    Czech Academy of Sciences Publication Activity Database

    Ek Weis, Johan; da Costa, Sara; Frank, Otakar; Kalbáč, Martin

    2014-01-01

    Roč. 251, č. 12 (2014), s. 2505-2508. ISSN 0370-1972 R&D Projects: GA MŠk LH13022 Institutional support: RVO:61388955 Keywords : chemical vapor deposition * graphene * isotope labeling Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.489, year: 2014

  6. Heating Isotopically Labeled Bernal Stacked Graphene: A Raman Spectroscopy Study

    Czech Academy of Sciences Publication Activity Database

    Ek Weis, Johan; da Costa, Sara; Frank, Otakar; Kalbáč, Martin

    2014-01-01

    Roč. 5, č. 3 (2014), s. 549-554. ISSN 1948-7185 R&D Projects: GA MŠk LL1301 Institutional support: RVO:61388955 Keywords : Bernal * graphene * isotopic labeling Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 7.458, year: 2014

  7. The use of stable isotopes and hydrogeochemical studies to characterize water resources in the semi-arid Sokoto Basin, Nigeria

    International Nuclear Information System (INIS)

    The Sokoto hydrological basin in Northwestern Nigeria belongs to a larger geographic unit, the Iullemmeden Basin in West Africa covering an estimated area of 700,000 Km2. It is a semi-arid region with mean annual rainfall (over a period of 90 years) ranging from 350mm at Kalmalo in the extreme north and 670mm (at Sokoto). The potential evapotranspiration at Sokoto is calculated to about 2,500mm/a, thus exceeding precipitation by as much as a factor of 5. The aim of this study is to characterize water resources in the basin and investigate the risk of pollution. This is to aid the planning and management of water resources in the semi-arid areas of northwestern Nigeria to meet the demands of the growing population. In order to achieve the aim of the present study more than 190 samples were taken from dugwells and tubewells, boreholes, lake as well as rivers Rima and Sokoto in four major sampling campaigns in the Federal Ministry of Water Resources (Nigeria) under the joint RAF/08/22 project with the International Atomic and Energy Agency, Vienna (Austria) and three fieldwork in the University of Ilorin (Nigeria) in collaboration with Technical University, Darmstadt (Germany). As a reference to groundwater 10 rainwater samples were collected from 3 different stations (Goronyo, Wurno and Sokoto) for isotope analyses. Physical parameters like temperature, pH, electrical conductivity (EC), dissolved oxygen and alkalinity were measured in the field using potable meters and 'AquaMerck' titration kits. Main chemical components and the environmental isotopes H-2, H-3, C-13, C-14 and O-18 have been analyzed. Stable isotopes ratios are expressed as delta in per mil relative to VSMOW (Vienna Standard Mean Ocean Water). The isotope precision of measurement based on VSMOW is ±0.15 per mille for 18O and ±1 per mille for 2H. Results of field analysis of the water samples have shown a pH range of 5.5 - 8.3; electrical conductivity of 45 -1, 155 μS/cm and total dissolved solids

  8. Cobwebs of Ophiuchus. I. Strands of (C-13)O - the mass distribution

    International Nuclear Information System (INIS)

    A 4.5 deg x 6.5 deg area of the Rho Ophiuchus molecular complex has been mapped in J = 1-0 (C-13)O with a 2.4 arcmin beam. The spatial distribution of (C-13)O, the distribution of clumps according to size, mass, density, and kinetic temperature are described. The distribution of material in the cloud is compared with the magnetic field distribution and with a shocked cloud model. Evidence supporting the role of shock in the cloud is found in the cloud morphology. 48 references

  9. Study of neutron deficient iridium isotopes by using laser spectroscopy

    International Nuclear Information System (INIS)

    Resonance ionization spectroscopy was performed on neutron deficient iridium isotopes 182-189Ir, 186Irm and stable isotopes 191,193Ir. Hyperfine spectra were recorded from the optical transition at 351,7 nm between the 5d76s24F9/2 ground state and the 5d76s6p 6F11/2 excited state. Radioactive iridium isotopes were obtained from β+/EC decay of radioactive mercury nuclei deposited on a graphite substrate. The radioactive mercury nuclei were produced at the ISOLDE facility at CERN through spallation reactions, by bombarding a molten lead target with the 1 GeV proton beam delivered by the PS-Booster. Magnetic dipole moments and spectroscopic quadrupole moments were extracted from the hyperfine spectra. The mean square charge radius variations, as deduced from the measured isotopic shift, show a sharp change between 187Ir and 186Irg, accompanied by a sudden increase in deformation: from β2 ∼ 0,16 to β2 > 0, 2. These results were analysed in the framework of an axial rotor plus one or two quasiparticles. The wave functions of the osmium and platinum cores which are used in order to describe the iridium nuclei were calculated from the HF+BCS method with the Skyrme SIII effective interaction. The cores were constrained to take the deformation parameters extracted from the isotopic shift measurements. One shows then that this sudden deformation change corresponds also to a change in the proton state that describes the odd nuclei ground state or that participates in the coupling with the neutron in odd-odd nuclei. This state is identified with the π3/2+[402] orbital for the smaller deformations nuclei and with the π1/2-[541] orbital stemming from the h9/2 subshell for bigger deformations nuclei. (author)

  10. Study of the stability of the gallium isotopes beyond the N = 50 neutron shell closure

    CERN Multimedia

    We propose to study the stability of the nuclear structure beyond N = 50 and Z = 28 with beams of neutron-rich gallium isotopes at the CRIS experiment at ISOLDE. The study of their hyperne structure and isotope shift will provide spins, magnetic dipole moments, electric quadrupole moments and changes in the mean-square charge radii. The $\\beta$-decay of $^{80}$Ga will be unambiguously measured using the technique of Laser Assisted Nuclear Decay Spectroscopy (LANDS). The half-lives of the very neutron-rich isotopes with N > 54 will be measured for their impact on the astrophysical ${r}$-process.

  11. International conference on isotopes in environmental studies - Aquatic Forum 2004. Book of extended synopses

    International Nuclear Information System (INIS)

    The International Conference on Isotopes in Environmental Studies: AQUATIC FORUM 2004, organized by the International Atomic Energy Agency (IAEA) was held in Monte-Carlo, Monaco, 25-29 October 2004. The principal objective of the Conference was to review recent achievements in the use of isotopic techniques to study marine and terrestrial environmental processes, transport of contaminants in the aquatic environment, climate change, computer modelling of environmental processes, present state of the art of isotopic techniques, data validation and syntheses, and the development of geographical information systems. This publication contains the extended synopses of presentations at the Conference

  12. Dynamic isotope power system (DIPS) applications study. Volume I. Summary. Final report

    International Nuclear Information System (INIS)

    The Nuclear Integrated Multimission Spacecraft (NIMS) is designed for communications, surveillance, navigation and meteorelogical missions. This study assesses th attributes of the Dynamic Isotope Power System (DIPS) for this spacecraft. These attributes include cost, system and mission compatibility, and survivability

  13. Dynamics of the Caspian Sea: Preliminary results of isotope studies

    International Nuclear Information System (INIS)

    The water level of the Caspian Sea, the world's largest inland water body, rose by approximately 2 m within the last 20 years. To explore the potential of isotope techniques for studying the water balance and dynamics of the Caspian Sea and aspects related to the recent sea level rise, two research-training cruises were carried out in September 1995 and 1996 within the framework of an IAEA technical co-operation project. The paper presents a preliminary evaluation of the results obtained so far. By correlating sea level fluctuations and freshwater inflow variations observed in previous studies, it has been found that changes of the sea level are caused by changes in the water budget, mainly in the river input. The water of the Caspian Sea is enriched in oxygen-18 with respect to the total inflow (rivers plus precipitation) by about 9 per mille. The vertical distribution of δ18O observed in the southern and central basins of the Caspian Sea indicates that the main water body of the sea (between 200 m and 800 m depth) is enriched in oxygen-18 with respect to the surface layer by approximately 0.3 per mille. This enrichment suggests that water at depth most probably represents the previous low level stand of the Caspian Sea (1950-1977) and that the total inflow exceeded the evaporation by about 10% during the recent sea level rise. Vertical temperature and salinity gradients observed during the 1995 and 1996 expeditions suggest that deep water exchange in the central and southern basins of the Caspian Sea cannot be triggered by cooling of surface water alone but also requires an increase of salinity. The presence of bomb tritium and tritiogenic helium-3 in the deep water of the central and southern basins points to rather intense vertical water exchange in both basins. The water ages calculated from tritium and helium-3 increase from shallow to deep water in both basins; near the bottom, a maximum model age of some 20 to 25 years was. (author) obtained

  14. The importance of having different isotopes in NMR/NQR studies

    International Nuclear Information System (INIS)

    One of the powers of Nuclear Magnetic Resonance (NMR) as a spectroscopic tool arises from the fact that each stable element of the periodic table (except for Ar and Tc) has at least one isotope that possesses a nuclear magnetic dipole moment and hence can be employed in a NMR experiment. For the benefit of the researcher, 36 elements have even several magnetic isotopes, e.g. H, Li, B, N, Cl, K, Cu, Xe, Ba. Furthermore, there are 62 elements which possess at least one isotope having a nuclear quadrupole moment and thus, in addition to NMR, allow Nuclear Quadrupole Resonance (NQR) experiments. Given this rich supply of isotopes, no wonder that chemical compounds with different isotopes of the same element, for instance H2O and D2O, play an important role in NMR studies. Well known are the structural investigations in liquids by NMR (high-resolution NMR) where, e.g., hydrogen is replaced by deuterium if a certain bond is of special interest. The hydrogen bond studies in ferroelectrics using also deuterium substitution are a typical example from solid-state physics. In our review, we will present less known but representative examples where the NMR study of two isotopes of the same element yields important information on very different characteristic features of the compound (structure, dynamics etc.). We will discuss the following examples: i) Determination of the type of molecular movements of a transient Xe molecule in the gas phase (by using the Xe isotopes 129 Xe and 131 Xe); ii) Classical nature of the isotope effect of the Li diffusion coefficient in Li metal (7 Li and 6 Li in solid Li); iii) Magnetic and electric origin of spin-lattice relaxation and other quantities in cuprate superconductors 63 Cu and 65 Cu); iv) Isotope shift of the temperature of the opening of the spin gap in the superconductor YBa2Cu4O8 (16 O and 18 O exchanged samples). (author)

  15. Fluid inclusion and stable isotope studies of hydrothermal vein deposits, Schwarzwald, Germany

    OpenAIRE

    Baatartsogt, Baldorj

    2006-01-01

    An integrated fluid inclusion and stable isotope study has been carried out on hydrothermal veins from the Schwarzwald district. More than 400 individual samples from 110 Variscan and post-Variscan deposits covering a large area of 120 by 40 km were studied by microthermometry, Raman spectroscopy, stable isotope analysis of minerals and fluid inclusions. The most straightforward method for the determination of paleofluid signatures is the direct extraction of fluid inclusion water from hy...

  16. Stable isotope study in geothermal fields in Kamojang and Dieng, Java Island

    International Nuclear Information System (INIS)

    A survey of the stable isotope composition of geothermal sources was initiated at several geothermal fields on the island of Java during 1988-1990. A further study was carried out in two geothermal fields, Kamojang and Dieng, which was approximately 400 km apart. The study was intended to provide an isotope database to monitor geothermal evolution resulting from exploitation and to identify the recharge area of the geothermal system. 1 fig

  17. Adulteration of honey : relation between microscopic analysis and delta C-13 measurements

    NARCIS (Netherlands)

    Kerkvliet, JD; Meijer, HAJ

    2000-01-01

    Upon routine microscopic analysis of some honey samples, parenchyma cells, single rings of ring vessels and epidermal cells are found. These cells originate from the sugar cane stem. We investigated whether there was a relation between these plant fragments and the delta C-13 value of honey. 17 hone

  18. Probing the possibility of a 12C13C abundance gradient from observations of interstellar CH+

    International Nuclear Information System (INIS)

    I have performed high signal-to-noise (SN /equals/ 300 to 500) observations of interstellar CH/sup /plus// at Lick Observatory and at CTIO of the reddened, early-type stars HD 183143, HD 24432, and HD 157038 in an effort to probe the existence of a 12C13C abundance gradient in our Galaxy

  19. Stereoselective synthesis of the C1–C13 segment of dolabelide B

    OpenAIRE

    Keck, Gary E.; McLaws, Mark D.

    2005-01-01

    The efficient construction of the C1–C13 segment of dolabelide B is described. A key element of the synthesis entails BITIP catalyzed asymmetric methallylation to establish the C7 stereocenter, which was then used to direct the stereoselective installation of the C9 and C11 centers through Evans reduction and 1,5-anti aldol condensation, respectively.

  20. Metabolic network analysis of Penicillium chrysogenum using C-13-labeled glucose

    DEFF Research Database (Denmark)

    Christensen, Bjarke; Nielsen, Jens

    2000-01-01

    Using C-13-labeled glucose fed to a penicillin-overproducing strain of Penicillium chrysogenum, the intracellular fluxes were quantified, and the presence of two new pathways, not previously described in this organism, is suggested. Thus, glycine was synthesized not only by serine hydroxymethyltr...

  1. Impact of transamination reactions and protein turnover on labeling dynamics in C-13-labeling experiments

    DEFF Research Database (Denmark)

    Grotkjær, Thomas; Åkesson, M.; Christensen, Bjarke;

    2004-01-01

    A dynamic model describing carbon atom transitions in the central metabolism of Saccharomyces cerevisiae is used to investigate the influence of transamination reactions and protein turnover on the transient behavior of C-13-labeling chemostat experiments. The simulations performed suggest that c...

  2. Isotope labeling strategies for NMR studies of RNA

    International Nuclear Information System (INIS)

    The known biological functions of RNA have expanded in recent years and now include gene regulation, maintenance of sub-cellular structure, and catalysis, in addition to propagation of genetic information. As for proteins, RNA function is tightly correlated with structure. Unlike proteins, structural information for larger, biologically functional RNAs is relatively limited. NMR signal degeneracy, relaxation problems, and a paucity of long-range 1H-1H dipolar contacts have limited the utility of traditional NMR approaches. Selective isotope labeling, including nucleotide-specific and segmental labeling strategies, may provide the best opportunities for obtaining structural information by NMR. Here we review methods that have been developed for preparing and purifying isotopically labeled RNAs, as well as NMR strategies that have been employed for signal assignment and structure determination.

  3. Study of polonium isotopes ground state properties by simultaneous atomic- and nuclear-spectroscopy

    CERN Multimedia

    Koester, U H; Kalaninova, Z; Imai, N

    2007-01-01

    We propose to systematically study the ground state properties of neutron deficient $^{192-200}$Po isotopes by means of in-source laser spectroscopy using the ISOLDE laser ion source coupled with nuclear spectroscopy at the detection setup as successfully done before by this collaboration with neutron deficient lead isotopes. The study of the change in mean square charge radii along the polonium isotope chain will give an insight into shape coexistence above the mid-shell N = 104 and above the closed shell Z = 82. The hyperfine structure of the odd isotopes will also allow determination of the nuclear spin and the magnetic moment of the ground state and of any identifiable isomer state. For this study, a standard UC$_{x}$ target with the ISOLDE RILIS is required for 38 shifts.

  4. Application of environmental isotopes in studies of biodegradation of organic contaminants in groundwater

    International Nuclear Information System (INIS)

    Groundwater contamination by organic contaminants is of major concern for implementing efficient water management strategies in aquifers used for domestic and industrial uses. Monitored natural attenuation (MNA) has been chosen as a method to manage groundwater contamination at many sites. Biodegradation is usually the main process limiting the spreading of dissolved contaminants and protocols are required to assess biodegradation. Successful implementation of monitored natural attenuation (MNA) requires a monitoring strategy that does not only demonstrate diminishing contaminant concentrations but also provides insight into the processes responsible for contaminant attenuation. Analysis of compound-specific isotope ratios is a new approach to gain such process-specific information. During microbial and chemical transformations, the reaction rate is often faster for molecules with light isotopes compared to molecules with heavy isotopes. This leads to a characteristic pattern of isotope ratios of reactants and transformation products. Stable isotope ratios can provide information on predominant biodegradation pathways in two ways: A degradation pathway may be identified based on an enrichment of heavy isotopes in the reactant as the reaction proceeds. Or, an intermediate of a degradation pathway can have a distinct isotopic composition, which makes it possible to distinguish it from other sources of the compound. Most of the isotope research has concentrated on BTEX (benzene, toluene, ethylbenzene and xylenes) and chlorinated compounds, the two more important groups of compounds commonly found in groundwater. Several studies have been carried out under laboratory conditions (microcosm experiments) to evaluate carbon isotope fractionation during aerobic and anaerobic biodegradation of organic contaminants. These studies have shown the occurrence of large carbon isotope fractionation for biodegradation of chlorinated compounds such as cis-1,2-dichloroethene (cis

  5. A study on structural evolution of 142-164Nd isotopes

    International Nuclear Information System (INIS)

    Constrained Hartree-Fock-Bogoliubov theory with SLy5 Skyrme force has been applied for even-even 142-164Nd isotopes to investigate the structural evolution of Nd isotopic chain. In this work, ground-state energies and charge radii of Nd isotopes have been carried out as in good agreement with the experimental data. The systematic investigation of ground-state shape evolution between spherical U(5) and axially deformed SU(3) for 142-164Nd has been studied by using potential energy curves

  6. Theoretical study of the isotope effects on the detachment thresholds of Si$^-$

    OpenAIRE

    Carette, T.; Godefroid, M

    2013-01-01

    The isotope effects in Si$^-$ bound levels are studied using the multi-configuration Hartree-Fock ab initio approach. Large scale calculations are carried out for the $3p^3\\ ^4S^o,\\, ^2D^o$ and $^2P^o$ multiplets of Si$^-$ and the $3p^2\\ ^3P$ multiplet of Si. We predict an anomalous isotope shift on the electron affinity, dominated by the specific mass shift, with a value of $IS(^e\\!\\!A)= -0.66(6)$ m$^{-1}$ for the ($30-28$) isotope pair. We also report hyperfine structure parameters for the ...

  7. Infrared study of isotopic exchange during methanation over supported rhodium catalysts: an inverse spillover effect

    International Nuclear Information System (INIS)

    Infrared spectroscopy has been employed to study the reduction of carbon dioxide on supported catalyst films. The investigation included isotopic labeling using D2 as the reduction gas. Isotopic exchange was observed for both CO2/D2 and CH4/D2 mixtures. The mechanism of this isotopic exchange involves migration of hydrogen from the support to the Rh sites, an ''inverse spillover effect''. A key intermediate in the dissociation of CO2 on the supported Rh films was a carbonyl hydride species. 21 refs., 2 figs

  8. Stable isotope studies of nephrite deposits from Fengtien, Taiwan

    Energy Technology Data Exchange (ETDEWEB)

    Yui, Tzenfu; Yeh, Hsuehwen (Univ. of Hawaii, Honolulu (USA)); Lee, Chihming Wang (National Taiwan Univ. Taipei (Taiwan))

    1988-03-01

    Metasomatic nephrite deposits (i.e., rodingites) occur between serpentinites and muscovite-quartz schist in the Fengtien area, eastern Taiwan. The {delta}{sup 18}O values of nephrite range from +4.5 to +5.3{per thousand} and the {delta}D values, from {minus}33 to {minus}68{per thousand}. The narrow range in the {delta}{sup 18}O values and wide variation in the {delta}D values indicate low water/rock ratios and multiple origins of the ambient H{sub 2}O during nephrite formation. The ultimate sources of the ambient H{sub 2}O are largely sea water for the early nephrite and meteoric water for the late nephrite. The temperature of nephrite formation is 320-420{degree}C: the estimated O-isotopic fractionation between nephrite (tremolite) and serpentine (antigorite) is 1.0 {plus minus} 0.2{per thousand} in this temperature range. Diopsidefels and epidotite are two other kinds of rodingite in the deposits. The {delta}{sup 18}O values of diopside from diopsidefels range from +3.7 to +4.5{per thousand}, the {delta}D values of clinozoisite from epidotite range from {minus}31 to {minus}34{per thousand} and the {delta}{sup 18}O value of one clinozoisite analyzed is +3.9{per thousand}. These data suggest that most diopsidefels formed in isotopic equilibrium with nephrite and that clinozoisite was not in isotopic equilibrium with either nephrite of diopsidefels. O-isotope compositions of both nephrite and diopsidefels cannot give conclusive evidence of their parental rocks. Circumstantial evidence, however, implies that the nephrite is derived from serpentinite whereas diopsidefels formed from unaltered ultramafic rocks.

  9. Multi-scale study of the isotope effect in ISTTOK

    Science.gov (United States)

    Liu, B.; Silva, C.; Figueiredo, H.; Pedrosa, M. A.; van Milligen, B. Ph.; Pereira, T.; Losada, U.; Hidalgo, C.

    2016-05-01

    The isotope effect, namely the isotope dependence of plasma confinement, is still one of the principal scientific conundrums facing the magnetic fusion community. We have investigated the impact of isotope mass on multi-scale mechanisms, including the characterization of radial correlation lengths (\\boldsymbol{L}{r} ) and long-range correlations (LRC) of plasma fluctuations using multi-array Langmuir probe system, in hydrogen (H) and deuterium (D) plasmas in the ISTTOK tokamak. We found that when changing plasma composition from the H dominated to D dominated, the LRC amplitude increased markedly (10–30%) and the \\boldsymbol{L}{r} increased slightly (~10%). The particle confinement also improved by about 50%. The changes of LRC and \\boldsymbol{L}{r} are congruent with previous findings in the TEXTOR tokamak (Xu et al 2013 Phys. Rev. Lett. 110 265005). In addition, using biorthogonal decomposition, both geodesic acoustic modes and very low frequency (<5 kHz) coherent modes were found to be contributing to LRC.

  10. Stable isotope variations in benthic primary producers along the Bosphorus (Turkey): A preliminary study

    International Nuclear Information System (INIS)

    Highlights: • Nitrogen pollution along the Bosphorus Strait was investigated. • C and N isotopic and elemental analyses on benthic primary producers were performed. • δ15N decreased, while δ13C and N% increased from north to south along the Strait. • Ulva lactuca was more useful than epiphytes as indicator of nitrogen pollution. • Preliminary isotopic analyses on resident organisms are useful monitoring tools. - Abstract: The Bosphorus Strait is a dynamic and complex system. Recent evidences showed nitrogen and heavy metal concentrations to follow opposite patterns across the Strait, suggesting a complex spatial organisation of the anthropogenic disturbance in this system. Here, we provide isotopic information on the origin and transportation of dissolved nitrogen along the Bosphorus. C and N isotopic and elemental analyses were performed on specimens of Ulva lactuca and associated epiphytes sampled in five locations across the Strait. Variations in C and N isotopic signatures were observed in U. lactuca, pointing to a decrease in the availability of anthropogenic organic dissolved nitrogen along a north-south direction. Conversely, epiphytes did not show isotopic or elemental patterns across the Strait. These results suggest that preliminary stable isotope surveys in extended costal systems basing on U. lactuca can represent a valuable tool to focus meaningful targets and hypotheses for pollution studies in the Mediterranean region

  11. Contribution to optimisation of Environmental Isotopes tracing in Hydrogeology. Case study of Madagascar

    International Nuclear Information System (INIS)

    The aim of this work is to suggest some improvements on the theory of interpretation and on the methodological approach for the optimum use of environmental isotopes tracing applied to hydrogeological investigation. A review of the theory of environmental isotopes used in hydrogeology has been made. The main constraints have been highlighted and led to some comments and proposals of improvement, in particular with regard to the continental effect on stable isotopes, to the seasonal variation of groundwater 14C content, and to the appropriate model for fractured crystalline aquifers. A literature survey on ten specific scientific papers, dealing with isotopic hydrology in miscellaneous types of aquifers and catchments, allowed to draw a synthesis of the hydrogeological, geochemical and isotopic constraints. A proposal of optimum methodological approach, taking into account the above mentioned constraints, have been inferred. The results of an on-going hydrogeological investigation carried out in the Southern crystalline basement and coastal sedimentary aquifers of Madagascar highlights an unusual methodological approach based on the lack of initial basic hydrogeological data. Besides, it shows to what extent the experience of the above mentioned research works can apply in the specific case of the complex aquifers of Madagascar. The lessons gained from this study contribute to enrich the synthesis of environmental isotopes constraints in hydrogeology and lead to a more realistic methodological approach proposal wich is likely to better make profitable the isotope hydrology technology

  12. Neutron-rich polonium isotopes studied with in-source laser spectroscopy

    CERN Document Server

    Dexters, Wim; Cocolios, T E

    This work studies the unknown region of neutron rich polonium isotopes. The polonium isotopes, with Z=84, lie above the magic lead nuclei (Z=82). The motivation for this research can mainly be found in these lead nuclei. When looking at the changes in the mean square charge radii beyond the N=126 shell gap, a kink is observed. This kink is also found in the radon (Z=86) and radium (Z=88) isotopes. The observed effect cannot be reproduced with our current models. The polonium isotopes yield more information on the kink and they are also able to link the known charge radii in lead isotopes to those in radon and radium. Additionally, the nuclear moments of the odd-neutron isotope $^{211}$Po are investigated. This nucleus has two protons and one neutron more than the doubly magic nucleus $^{208}$Pb. Nuclear moments of isotopes close to this doubly magic nucleus are good tests for the theoretic models. Besides pushing the models to their limits, the nuclear moments of $^{211}$Po also yield new information on the f...

  13. Isotopic and hydrochemical study of the effect of tannery effluents on groundwater quality in Kasur area

    International Nuclear Information System (INIS)

    Isotopic and conventional techniques were employed to study groundwater recharge mechanism, and the effect of tannery effluents on the quality of groundwater in Kasur area. Water samples were collected from hand pumps, deep wells and pond water. The physico-chemical parameters were measured in the field and stable isotopes of H/sup 2/ and O/sup 18/ were analysed by using GD-150 gas source isotope ratio mass spectrometer. Depleted isotopic contents of delta H/sup 2/ and delta O/sup 18/ characterize canal recharge, enriched isotopic values are associated with rain recharge and intermediate values show the mixing of water from different sources. The shallow groundwater has depleted isotopic values and is being recharged by the canal. However, isotopic signature of shallow groundwater in the surroundings of the pond has been modified by the seepage of the pond water. The deuterium excess values are low showing the effect of evaporated pond water and these values increase as the distance from the pond increases. Electrical conductivity values and chloride contents decrease along the depth. The deep groundwater that can be termed as the native groundwater is being recharged by rains at piedmont area/bedrock outcrops. Results indicate that the quality of shallow groundwater has been deteriorated in the vicinity of stagnant pond water but quality of deep groundwater is good. Chromium is absent in groundwater, its penetration is limited up to a maximum depth of 10 meters. (author)

  14. Fundamental studies in isotope chemistry. Progress report, 1 August 1982-1 August 1983

    International Nuclear Information System (INIS)

    Interest in a search for superheavy elements present in nature as a remnant of the big bang or through continuous production by cosmic rays has prompted us to study the isotope chemistry of superheavy elements. Calculations of the fractionation factors of superheavy elements of masses 10, 100, 1000, and in the form of isotopes of hydrogen, carbon, selenium and uranium against the light naturally occurring isotope of the element show that the superheavy isotope, even of infinite mass, will not be sufficiently fractionated in single stage natural processes to obscure its chemistry. Calculations have been made of the elementary separation factors of superheavy isotopes of carbon and oxygen by fractional distillation of CO at 800K. The fractionation factors are discussed in terms of a model for liquid CO in good agreement with experimental data on 13C16O and 12C18O. Calculations for very heavy isotopic forms of CO reveal for the first time the coupling effect between translation and internal vibration in the liquid. It is shown that a 1ow temperature distillation plant, such as the Los Alamos COLA plant, has a significant potential for enrichment of superheavy isotopes of carbon. The maximum enrichment factor is 1055

  15. Lead isotope ratios as a tracer for lead contamination sources: A lake Andong case study

    Directory of Open Access Journals (Sweden)

    Kim Y. H

    2013-04-01

    Full Text Available The objective of this study was to evaluate stable Pb isotope signatures as a tracer for Pb contamination in Lake Andong. For Pb isotope analysis, we collected water and sediment from Lake Andong, particles in the air, soils, and stream water, mine tailings, sludge and wastewater from zinc smelting around lake Andong watershed. The results showed that Pb isotope ratios (206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb for zinc concentrate were 18.809 ± 0.322, 15.650 ± 0.062, and 38.728 ± 0.421, respectively. In wastewater, isotopic ratio values (206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb were 17.363 ± 0.133, 15.550 ± 0.025, and 37.217 ± 0.092, respectively. Additionally, isotopic ratio values (206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb for sludge were 17.515 ± 0.155, 15.537 ± 0.018, and 37.357 ± 0.173, respectively. These values were similar to those in zinc and lead concentrate originated from Canada and South America. In contrast, Pb isotope ratios of soil, tailings and sediment from Lake Andong were similar to those of Korean ore. Atmospheric particles showed different patterns of Pb isotope ratios from sediments, soils, and zinc smelting and this needs further investigation in order to identify atmospheric Pb sources.

  16. A hydrogen gas-water equilibration method produces accurate and precise stable hydrogen isotope ratio measurements in nutrition studies

    Science.gov (United States)

    Stable hydrogen isotope methodology is used in nutrition studies to measure growth, breast milk intake, and energy requirement. Isotope ratio MS is the best instrumentation to measure the stable hydrogen isotope ratios in physiological fluids. Conventional methods to convert physiological fluids to ...

  17. Experimental Study of Abiotic Organic Synthesis at High Temperature and Pressure Conditions: Carbon Isotope and Mineral Surface Characterizations

    Science.gov (United States)

    Fu, Qi; Socki, R. A.; Niles, P. B.

    2010-01-01

    Abiotic organic synthesis processes have been proposed as potential mechanisms for methane generation in subseafloor hydrothermal systems on Earth, and on other planets. To better understand the detailed reaction pathways and carbon isotope fractionations in this process under a wide range of physical and chemical conditions, hydrothermal experiments at high temperature (750 C) and pressure (0.55 GPa) were performed using piston cylinder apparatus. Formic acid was used as the source of CO2 and H2, and magnetite was the mineral catalyst. The chemical and carbon isotopic compositions of dissolved organic products were determined by GC-C-MS-IRMS, while organic intermediaries on the mineral catalyst were characterized by Pyrolysis-GC-MS. Among experimental products, dissolved CO2 was the dominant carbon species with a relative abundance of 88 mol%. Dissolved CH4 and C2H6 were also identified with a mole ratio of CH4 over C2H6 of 15:1. No dissolved CO was detected in the experiment, which might be attributable to the loss of H2 through the Au capsule used in the experiments at high temperature and pressure conditions and corresponding conversion of CO to CO2 by the water-gas shift reaction. Carbon isotope results showed that the 13C values of CH4 and C2H6 were -50.3% and -39.3% (V-PDB), respectively. CO2 derived from decarboxylation of formic acid had a (sigma)C-13 value of -19.2%, which was 3.2% heavier than its source, formic acid. The (sigma)C-13 difference between CO2 and CH4 was 31.1%, which was higher than the value of 9.4% calculated from theoretical isotopic equilibrium predictions at experimental conditions, suggesting the presence of a kinetic isotope effect. This number was also higher than the values (4.6 to 27.1%) observed in similar experiments previously performed at 400 C and 50 MPa with longer reaction times. CH4 is 11.0% less enriched in C-13 than C2H6. Alcohols were observed as carbon compounds on magnetite surfaces by Pyrolysis-GC-MS, which confirms

  18. A stable isotope study of three deposits in the Alligator Rivers Uranium Field, N.T

    International Nuclear Information System (INIS)

    Three major uranium deposits of the Alligator Rivers Uranium Field (Jabiluka One and Two, Koongarra, and Ranger 1), which occur in the Lower Proterozoic Cahill Formation have been isotopically examined. This study is so far the most extensive stable isotope investigation of minerals associated with uranium mineralisation in the Pine Creek Geosyncline. The data obtained relate to (1) the evolution of the Geosyncline, from approximately 2500 m.y. to younger geological periods, (2) the onset of bacterial sulphate reduction as a major process, and (3) the evolution of seawater sulphate sulphur isotope compositions to 34S enriched values, shown from at least the Cambrian onwards. The isotope data have been obtained from sulphides, carbonates and organic matter (identified as graphite in the areas studied), from both ore-zones and adjacent sediments

  19. Studies of geothermal background and isotopic geochemistry of thermal waters in Jiangxi Province

    International Nuclear Information System (INIS)

    The terrestrial heat flow measurement, isotope and geochemical techniques have been systematically applied to the geothermal systems in Jiangxi Province. Results show that the thermal waters in the study area all belong to the low-medium temperature convective geothermal system, which essentially differs from high temperature geothermal systems with deep magmatic heat sources. It has been proven that the isotope and geochemical techniques are very useful and effective in geothermal exploration. (13 refs., 14 tabs., 8 figs.)

  20. The use of stable isotopes for studies on the physiology of plants

    International Nuclear Information System (INIS)

    The use of the stable isotopes 15N, 18O, 13C for studies on the physiology of plants especially of plants grown under natural environment conditions is reviewed. Analysis of isotopic discrimination give estimates of the various patterns of carbon and nitrogen nutrition and of the rate of water circulation. The method can also be used for paleoclimatology and for the detection of frauds in food products

  1. Environmental isotope study of the deep groundwaters in northern Switzerland

    International Nuclear Information System (INIS)

    The paper presents a combined interpretation of the results of isotope and hydrochemical analyses of deep groundwaters, especially as encountered in the six Nagra deep boreholes in northern Switzerland. In the investigated area, several regional aquifers exist in the normal stratified sedimentary cover, as also in the deposits of the permo-carboniferous trench and in the rocks of the crystalline basement. The different groundwaters can be characterized by their chemical composition and stable isotope (2H and 18O) contents. The results of 14C and 13C analyses, as far as they can be corrected for chemical reactions and isotope exchange processes within the aquifer, can be used to give information on the ranges of residence times, whereas young groundwater components can be detected by 3H analyses. The process of interpretation is going on and the final synthesis work has not yet been completed; however, the state of the current picture concerning the deep groundwaters in northern Switzerland can be characterized as follows: The groundwaters within the sedimentary aquifers of the Lower Freshwater Molasse (USM) and Malm, the Keuper and the Upper Muschelkalk have evolved almost separately. For the USM/Malm groundwater different indications suggest a gradual mixing process going on between a low-mineralized younger groundwater component and a highly mineralized former formation water. The groundwater in the Keuper aquifer as sampled at the Riniken borehole seems to have evolved almost with no contact with near-surface components. The groundwaters of the aquifer of the Upper Muschelkalk show a wide variety of mixing processes with near-surface groundwaters, depending on the local geological situation (e.g. outcrops, tectonic events) and the induced pattern of the hydrodynamic flow-systems. In contrast, interformational mixing influences are found in the groundwaters within the deeper sedimentary aquifers of the Buntsandstein and the Upper Permian and the underlying

  2. Chemical and environmental isotopes study of precipitation in Syria

    International Nuclear Information System (INIS)

    Chemical and isotopic compositions of monthly precipitation were monitored at 12 stations distributed over the entire region in Syria for a period of 4 years from December 1999 to April 2003. Amount of precipitation and mean air temperature of rain monthly were also recorded. The conductivity of rain waters varies between 35 μ/cm in the mountainous stations and 336 μ/cm at Deir Az-Zor station. Excepted Tartous station, the mean value of Cl in the rainfall in all station is 3.8 mg/l. The seasonal variations in δ18O are smaller at west stations than to the east stations due to low seasonal temperature variations. All stations are characterized by water lines with slopes significantly lower than GMWL, except Bloudan, suggesting the influence of local factors on the isotopic composition of the precipitation. d-excess values decrease from 19% in the western part to 13% in the eastern part of Syria, indicating the influence of the precipitation generated by the air masses coming from the Mediterranean Sea over Syria. A reliable altitude effect represent by depletion of heavy stable isotopes of about -0.21, and -1.47, per 100 m elevation of 18O and δ2H, respectively. Monthly tritium activity and seasonal variations pattern are low in the west stations than at the east stations. The weighted mean tritium values are between 3 to 9 TU during 2000-2003, and it is increasing with distance from the Syrian coast by 1 TU /100 Km. (author)

  3. Molecular modeling study of lithium isotopic separation by crown-ethers in ethanol

    International Nuclear Information System (INIS)

    The isotopic separation of lithium ion isotopes is studied at the CEA in Pierrelatte using a liquid chromatography technique. Exchange systems are composed by crown-ethers grafted on silica (12C4, 15C5, B15C5, DB15C5, 18C6, B18C6). Lithium is introduced as a salt melted in ethanol. This work concerns the theoretical study of lithium isotopic exchange reactions with those systems. After a brief presentation of isotope separation techniques and isotopic effects (Chap.I), we describe the methods of theoretical chemistry used in this work (Chap. II). In chapter III, we test AM1 and PM3 semi-empirical methods for the treatment of Li+ /crown-ether species. Then, we calculate isotopic separation factors via ab initio and semi-empirical calculations for the exchange reactions in vacuum. The different crown-ethers are considered with and without graftings arms. Studies of exchange reactions in ethanol are presented in chapter IV. First, each species of the reaction are solvated by a few ethanol molecules. Isotopic separation factors calculated show a large effect of the solvent on the exchange reaction. The effect of the grafting arm has been investigated using hybrid quantum mechanics/molecular mechanics (QM/MM) molecular dynamics for species with the 12C4. Trajectories have been generated successively with 7Li and 6Li. Atomic velocity autocorrelation functions have allowed the access to vibrational frequencies necessary to calculate isotopic separation factors. The last chapter is devoted to methodological developments made during this Ph.D. We propose an approach to treat long range electrostatic interactions in hybrid QM/MM method, relying on a lattice summation technique. (author)

  4. Isotope studies on the comparative efficiency of nitrogenous sources

    International Nuclear Information System (INIS)

    In a growth chamber experiment with 15N-labelled potassium nitrate, ammonium sulphate and urea at 75 and 150kg nitrogen/ha and ammonium nitrate at 150kg nitrogen/ha, nitrogen application produced significant responses of dry matter yield and total nitrogen uptake by shoot and root of barley in chernozemic dark brown Elstow silt loam and deep black Hoey clay soil. Total nitrogen removal per pot and isotope-derived criteria, viz. percentage nitrogen derived from fertilizer, 'A' value and percentage fertilizer nitrogen utilization, indicated that potassium nitrate was the most efficient and urea the least

  5. Zinc absorption study using an enriched stable isotope (70Zn)

    International Nuclear Information System (INIS)

    A weaning food from fermented soybean was prepared for increasing the bioavailability of zinc. The zinc absorption was compared with that of a weaning food from non-fermented soybean and normal staple food. A stable isotope tracer technique (70Zn) and neutron activation were used for determining the absorption of zinc. Nine children aged 7 to 18 months were tested. Zinc bioavailability of weaning food from fermented soybean is higher than that of normal weaning food. The weight increment and zinc nutrition of children having weaning food from fermented soybean are improved by this diet. 5 tabs

  6. Preliminary isotopic study of Lake Asal system (Republic of Djibouti)

    International Nuclear Information System (INIS)

    The saline Lake Asal at 155 m below sea level in the Afar Rift (Republic of Djibouti) is fed mainly by sea water. In spite of the intense evaporation (about 3 m annually), the 18O and deuterium enrichments of the lake water are relatively low, because of the reduced activity of water as a consequence of the high salt content. Isotopic balance of the lake, as well as lithium and sulphate balances, support the hypothesis of leakages from the lake of about 15 to 20% of the inflow. (author)

  7. Isotope effects on chemical shifts in the study of intramolecular hydrogen bonds

    DEFF Research Database (Denmark)

    Hansen, Poul Erik

    2015-01-01

    The paper deals with the use of isotope effects on chemical shifts in characterizing intramolecular hydrogen bonds. Both so-called resonance-assisted (RAHB) and non-RAHB systems are treated. The importance of RAHB will be discussed. Another very important issue is the borderline between “static......” and tautomeric systems. Isotope effects on chemical shifts are particularly useful in such studies. All kinds of intramolecular hydrogen bonded systems will be treated, typical hydrogen bond donors: OH, NH, SH and NH+, typical acceptors C=O, C=N, C=S C=N−. The paper will be deal with both secondary...... and primary isotope effects on chemical shifts. These two types of isotope effects monitor the same hydrogen bond, but from different angles...

  8. Stable isotope labeling of protein by Kluyveromyces lactis for NMR study

    Energy Technology Data Exchange (ETDEWEB)

    Sugiki, Toshihiko [Japan Biological Informatics Consortium (JBiC) (Japan); Shimada, Ichio, E-mail: shimada@iw-nmr.f.u-tokyo.ac.jp; Takahashi, Hideo [Biomedicinal Information Research Center (BIRC), National Institute of Advanced Industrial Science and Technology (AIST) (Japan)], E-mail: hid.takahashi@aist.go.jp

    2008-11-15

    Stable isotope labeling for proteins of interest is an important technique in structural analyses of proteins by NMR spectroscopy. Escherichia coli is one of the most useful protein expression systems for stable isotope labeling because of its high-level protein expression and low costs for isotope-labeling. However, for the expression of proteins with numerous disulfide-bonds and/or post-translational modifications, E. coli systems are not necessarily appropriate. Instead, eukaryotic cells, such as yeast Pichia pastoris, have great potential for successful production of these proteins. The hemiascomycete yeast Kluyveromyces lactis is superior to the methylotrophic yeast P. pastoris in some respects: simple and rapid transformation, good reproducibility of protein expression induction and easy scale-up of culture. In the present study, we established a protein expression system using K. lactis, which enabled the preparation of labeled proteins using glucose and ammonium chloride as a stable isotope source.

  9. Stable isotope labeling of protein by Kluyveromyces lactis for NMR study

    International Nuclear Information System (INIS)

    Stable isotope labeling for proteins of interest is an important technique in structural analyses of proteins by NMR spectroscopy. Escherichia coli is one of the most useful protein expression systems for stable isotope labeling because of its high-level protein expression and low costs for isotope-labeling. However, for the expression of proteins with numerous disulfide-bonds and/or post-translational modifications, E. coli systems are not necessarily appropriate. Instead, eukaryotic cells, such as yeast Pichia pastoris, have great potential for successful production of these proteins. The hemiascomycete yeast Kluyveromyces lactis is superior to the methylotrophic yeast P. pastoris in some respects: simple and rapid transformation, good reproducibility of protein expression induction and easy scale-up of culture. In the present study, we established a protein expression system using K. lactis, which enabled the preparation of labeled proteins using glucose and ammonium chloride as a stable isotope source

  10. A study on zinc isotope fractionation in a benzo crown resin/acetone system

    International Nuclear Information System (INIS)

    Zinc isotope fractionation has been studied in different cavities of crown ether resins that were synthesized in porous silica beads. Displacement chromatography was performed, as a breakthrough manner, in glass columns by feeding in a zinc chloride solution. From the mass analysis of effluents, the heavier isotopes of zinc were enriched at the beginning of the zinc adsorption band. The front maximum enrichment (1.0168), separation coefficient (8.1 x 10-4), and smaller HETP (0.205 cm) for the isotopic pair 68Zn/64Zn were obtained with the use of the benzo-15-crown-5 resin. Zinc isotope fractionation was obviously affected by the cavity size of the crown ethers. (author)

  11. Study of isotopic selectivity in laser resonance ionization of lutetium atom

    International Nuclear Information System (INIS)

    Using numerical simulation method in terms of rate equation approximation, laser-induced isotopic selectivity of the scheme of resonance ionization: 5d6s22D3/2(573.655 nm)→5d6s6p 4F3/2 (642.518 nm)→6s6p24P1/2(643.548 nm)→Autoionization state was studied. The function of isotopic selectivity on laser wavelength was calculated for the parameters matching real experimental conditions by this method. The results calculated were well met with the experimental. The dependences of laser-induced isotopic selectivity on the laser parameters, such as wavelength, bandwidth and intensity, were discussed in view of the interaction of linearly polarized light with lutetium atom. The approaches that isotopic ratio were accurately determined by laser resonance ionization mass spectrometry in the case of certain laser parameters were presented. This theoretical method may be also used to study the isotopic selectivity of other elements and select the scheme of resonance ionization of laser isotope separation

  12. Oxygen isotope effects in the manganates and cuprates studied by electron paramagnetic resonance

    International Nuclear Information System (INIS)

    We present the results of the oxygen isotope effect study in colossal magnetoresistive manganate La1-xCaxMnO3+y using electron paramagnetic resonance (EPR). We observed strong isotope effects on EPR intensity and linewidth which can be explained by a model where a bottlenecked spin relaxation takes place from the exchange-coupled constituent Mn4+ ions via the Mn3+ Jahn-Teller ions to the lattice. For x = 0.2 the ferromagnetic exchange energy J exhibits a 16O/18O oxygen isotope effect of ∝-10%. The observed isotope effects suggest the presence of Jahn-Teller polarons in these materials. We also report the results of the similar study in cuprate superconductors La2-xSrxCuO4. Experiments showed large oxygen isotope effect on EPR linewidth. It was found that isotope effect is strong in samples with small Sr doping and decreases with Sr concentration increase. These results provide the first microscopic evidence for the polaronic charge carriers in the cuprate superconductors. (orig.)

  13. The Hemlo gold deposit, Ontario: a geochemical and isotopic study

    International Nuclear Information System (INIS)

    The Hemlo deposit, near Marathon, Ontario, is one of the largest gold deposits in North America. It is stratiform within Archean metamorphosed volcano-sedimentary rocks. The main ore zone is composed of pyritic, sericitic schist, and massive barite. This is the first report of stratiform barite in the Archean of North America, but other occurrences have since been found west of Hemlo. The mineralization is substantially enriched in Au, Mo, Sb, Hg, Tl and V and lacks carbonate. Because of metamorphism and deformation of the body its genesis is uncertain. 87Sr/86Sr of 0.7017 for barite from the deposit is similar to that of the sedimentary barite west of Hemlo and to initial ratios of contemporaneous volcanic rocks. At the base of the main ore zone, barite with delta34S of +8 to +12 per mille was deposited with approx. 0 per mille pyrite. Upward, both barite and pyrite get isotopically lighter, with minimum values for pyrite, to -17.5 per mille, in non-baritic schist forming the upper part of the ore zone. In drill section, Au grades correlate with the isotopic composition of pyrite. This, and the association of fractionated sulphide with sulphate, suggests that Au, pyrite and barite were deposited contemporaneously. The results are discussed. (author)

  14. Chemical and environmental isotope study of precipitation in Syria

    International Nuclear Information System (INIS)

    Waters from a network of rainfall collection covering mine meteorological stations distributed mainly in the western part of Syria have been assayed using chemical and environmental isotope techniques for a period of 5 months from Dec. 1989 to Apr. 1990. The chemistry of rain waters falling over the mountainous stations shows a low solute concentration (20-105 mg 1-1) compared with those falling over the coastal and anterior stations (50-210 mg 1-1). The rain waters was generally characterized by a high deuterium excess (d=19%) compared with that of typical global meteoric waters (d=10%). The estimated deuterium excess is lower than that for the eastern Mediterranean meteoric waters (d=22%). The altitude effect is shown up by a depletion of heavy stable isotopes of about - 0.23% and -1.65% per 100 m elevation of δ 18O and δD, respectively. The spatial distribution pattern of tritium contents shows a gradual build up with increasing distance from the Syrian coast. The weighted mean tritium content in rain waters falling over the country is estimated to amount to 9.5 tritium units (TU) during the period of observation. (author)

  15. Environmental isotopes used in a hydrogeological study of Northeastern Brazil

    International Nuclear Information System (INIS)

    With the exception of the coastal strip the Brazilian Northeastern region is notoriously characterized by deficient water resources, as a consequence of a low and irregular precipitation, high evaporation and evapotranspiration rates and soils with low infiltration capacity. For a better understanding of the hydrological problems, isotope techniques have been used in this area since 1969. A report is made on the data on environmental isotopes (D, 18O, T and 14C) obtained for the region so far, especially from the eastern part comprising the states of Ceara, Rio Grande do Norte, Paraiba and Pernambuco, For the crystalline area, the data available indicate that the conditions for recharge are such that the infiltrating water does not undergo significant previous evaporation; the turnover times estimated from T concentration are between 10 and 100 years. For the Potiguar sedimentary basin, the water in the main aquifer, the Acu sandstone, shows very low 14C content age of more than 30 000 years, and the deuterium concentration and 18O suggested some changes in the climate in the region. (author)

  16. Studies of isotopic hydrology in Latin America 2006

    International Nuclear Information System (INIS)

    Policies for the exploitation of groundwater as a complement to surface water resources are frequently based on short term planning and may not be sustainable over time. The objective of sustainable groundwater management is to use groundwater in conjunction with surface waters in such a way that a state of equilibrium is reached in terms of both quantity and quality of water. This type of management allows these underground resources to be preserved for future generations. Conventional and isotope techniques allow information to be obtained on the most important hydrogeological parameters such as identification and evaluation of recharge and discharge area and rates, the available volume of groundwater to be estimated, hydrological interconnections between aquifers and surface waters, direction and velocity of groundwater flows, etc., which allow mathematical flow models to be established and validated. Mathematical models are indispensable tools for sustainable water resource management. The objective of the IAEA technical cooperation project RLA/8/031 was to contribute to improve the hydrogeological understanding of the aquifers through the use of isotopic and conventional techniques, with the final aim of improving groundwater resource management in several countries in Latin America. The present paper briefly summarizes the technical results obtained during the four years of the regional project

  17. Mercury species transformations in marine and biological systems studied by isotope dilution mass spectrometry and stable isotope tracers

    OpenAIRE

    Lambertsson, Lars

    2005-01-01

    This thesis focuses on the implementation of species-specific isotope dilution (SSID) methodology and stable isotope tracers to determine mercury species occurrence and transformation processes in-situ and during sample treatment. Isotope enriched tracers of methyl-, ethyl- and inorganic mercury were synthesised and applied in different combinations to marine and biological samples. Experimental results were obtained using gas chromatography-inductively coupled plasma-mass spectrometry (GC-IC...

  18. Chemical vs. biotechnological synthesis of C13-apocarotenoids: current methods, applications and perspectives.

    Science.gov (United States)

    Cataldo, Vicente F; López, Javiera; Cárcamo, Martín; Agosin, Eduardo

    2016-07-01

    Apocarotenoids are natural compounds derived from the oxidative cleavage of carotenoids. Particularly, C13-apocarotenoids are volatile compounds that contribute to the aromas of different flowers and fruits and are highly valued by the Flavor and Fragrance industry. So far, the chemical synthesis of these terpenoids has dominated the industry. Nonetheless, the increasing consumer demand for more natural and sustainable processes raises an interesting opportunity for bio-production alternatives. In this regard, enzymatic biocatalysis and metabolically engineered microorganisms emerge as attractive biotechnological options. The present review summarizes promising bioengineering approaches with regard to chemical production methods for the synthesis of two families of C13-apocarotenoids: ionones/dihydroionones and damascones/damascenone. We discuss each method and its applicability, with a thorough comparative analysis for ionones, focusing on the production process, regulatory aspects, and sustainability. PMID:27154347

  19. Study of Neutron-Deficient $^{202-205}$Fr Isotopes with Collinear Resonance Ionization Spectroscopy

    CERN Document Server

    De Schepper, Stijn; Cocolios, Thomas; Budincevic, Ivan

    The scope of this master’s thesis is the study of neutron-deficient $^{202−205}$Fr isotopes. These isotopes are inside the neutron-deficient lead region, a region that has shown evidence of shape coexistence. For this thesis, this discussion is limited to the phenomenon where a low lying excited state has a different shape than the ground state. Shape coexistence is caused by intruder states. These are single-particle Shell Model states that are perturbed in energy due to the interaction with a deformed core. In the neutron-deficient lead region the main proton intruder orbit is the 3s$_{1/2}$orbit. When going towards more neutron-deficient isotopes, deformation increases. The $\\pi3s_{1/2}$orbit will rise in energy and will eventually become the ground state in odd- A bismuth (Z=83) isotopes. It is also observed in odd-A astatine (Z=85) isotopes, already in less neutron-deficient nuclei. The same phenomenon is expected to be present francium (Z=87) isotopes already at $^{199}$Fr. Although it is currently ...

  20. The study of the deuterium isotopic fractionation through the cell membrane of the plant

    International Nuclear Information System (INIS)

    The purpose of this study is to prove that there is a water deuterium isotope fractionation when the water passes through the cell membrane. The carrots (Daucus carota) were grown in vitro in a Murashige and Skoog mineral-salt medium and have been exposed to a water solution with a uniform isotopic content. After seven days the cell culture was filtered and the cell water was vacuum extracted. The water from aqueous solution and the cell water were analyzed for hydrogen by isotope ratio mass spectrometry. The procedure was repeated for 14 and 21 day old cell cultures. The measurements have revealed a water deuterium isotopic fractionation between extra-cellular water and cellular water. The deuterium content was found to be higher within the cells by 10o/oo for non-embryonic cells and 13 o/oo for the embryonic cells. This fractionation is a non-evaporative fractionation between intracellular and extra-cellular water and it represents a new step in the overall fractionation of deuterium water in the plants. The existence of such isotopic fractionation through the cell membrane implies that the relationship between the deuterium content of cellulose nitrate in plant and meteoric water should be revised. Also, this finding is of interest for understanding the balance and dynamics of the hydrogen isotopes in the environment. (authors)

  1. Study of variations of stable isotopes in precipitation: case of Antananarivo

    International Nuclear Information System (INIS)

    The isotopic signature of precipitation is the input signal in any study of hydrological cycle. The scientific objective of this work is to better understand the isotopic variations in precipitation and identify their processes. We used the network of measurement GNIP (Global Network of Isotopes in Precipitation) in which data is acquired by the International Atomic Energy Agency through isotope hydrology laboratory at INSTN-Madagascar. Analyzes stable isotopes (18O and 2H), were performed at a monthly time step. We were able to confirm the relative importance of different mechanisms governing the isotopic composition of precipitation. The spatial distribution of abundance ratios of Antananarivo rain is in fact dictated by the temperature which follow indirectly from the effects of altitude and seasonal variations. At the monthly scale, local meteoric water line δ2H versus δ18O shows the specificity of Antananarivo (deuterium excess of 17.5‰ ). Additionally, seasonal variations in precipitation is related to the temperature such that in summer (d=15‰) and winter (d=18‰)

  2. Carbon isotopic studies of individual lipids in organisms from the Nansha sea area, China

    Institute of Scientific and Technical Information of China (English)

    DUAN; Yi; SONG; Jinming; ZHANG; Hui

    2004-01-01

    Carbon isotopes of individual lipids in typical organisms from the Nansha sea area were measured by the GC-IRMS analytical technique. δ13C values of saturated fatty acids in different organisms examined are from -25.6‰ to -29.7‰ with the average values ranging from -26.4‰ to -28.2‰ and the variance range of 1.8‰ between different organisms is also observed.Unsaturated fatty acids have heavy carbon isotopic compositions and the mean differences of 2.9‰-6.8‰ compared to the same carbon number saturated fatty acids. δ13C values of n-alkanes range from -27.5‰ to -29.7‰ and their mean values, ranging from -28.6‰ to -28.9‰, are very close in different organisms. The mean difference in δ13C between the saturated fatty acids and n-alkanes is only 1.5‰, indicating that they have similar biosynthetic pathways. The carbon isotopic variations between the different carbon-number lipids are mostly within ±2.0‰, reflecting that they experienced a biosynthetic process of the carbon chain elongation. At the same time, the carbon isotopic genetic relationships between the biological and sedimentary lipids are established by comparative studies of carbon isotopic compositions of individual lipids in organisms and sediments from the Nansha sea area, which provides scientific basis for carbon isotopic applied research of individual lipids.

  3. Study of the Photon Strength Functions for Gadolinium Isotopes with the DANCE Array

    International Nuclear Information System (INIS)

    The gadolinium isotopes are interesting for reactor applications as well as for medicine and astrophysics. The gadolinium isotopes have some of the largest neutron capture cross sections. As a consequence they are used in the control rod in reactor fuel assembly. From the basic science point of view, there are seven stable isotopes of gadolinium with varying degrees of deformation. Therefore they provide a good testing ground for the study of deformation dependent structure such as the scissors mode. Decay gamma rays following neutron capture on Gd isotopes are detected by the DANCE array, which is located at flight path 14 at the Lujan Neutron Scattering Center at Los Alamos National Laboratory. The high segmentation and close packing of the detector array enable gamma-ray multiplicity measurements. The calorimetric properties of the DANCE array coupled with the neutron time-of-flight technique enables one to gate on a specific resonance of a specific isotope in the time-of-flight spectrum and obtain the summed energy spectrum for that isotope. The singles gamma-ray spectrum for each multiplicity can be separated by their DANCE cluster multiplicity. Various photon strength function models are used for comparison with experimentally measured DANCE data and provide insight for understanding the statistical decay properties of deformed nuclei.

  4. Laser Spectroscopy Study on the Neutron-Rich and Neutron-Deficient Te Isotopes

    CERN Multimedia

    2002-01-01

    We propose to perform laser spectroscopy measurements on the Te isotopes. This will give access to fundamental properties of the ground and rather long-lived isomeric states such as the change in the mean square charge radius ($\\delta\\langle$r$^2_c\\rangle$) and the nuclear moments. For these medium-mass isotopes, at this moment the optical resolution obtained with RILIS is not high enough to perform isotope shift measurements. Thus we will use the COMPLIS experimental setup which allows Resonant Ionization Spectroscopy (RIS) on laser desorbed atoms. The 5p$^{4}$ $^{3}$P$_{2} \\rightarrow$ 5p$^{3}$ 6s $^{3}$S$_{1}$ and 5p$^{4}$ $^{3}$P$_{2} \\rightarrow$ 5p$^{3}$ 6s $^{5}$S$_{2}$ optical transitions have been used to perform, on the stable Te isotopes, the tests required by the INTC committee. For this purpose stable-ion sources have been built and Te isotopes have been delivered as stable beams by the injector coupled to the COMPLIS setup. ISOLDE offers the opportunity for studying the Te isotope series over a ...

  5. Hydrogen isotope variability in prairie wetland systems: implications for studies of migratory connectivity.

    Science.gov (United States)

    Bortolotti, Lauren E; Clark, Robert G; Wassenaar, Leonard I

    2013-01-01

    Hydrogen isotopes (delta2H) are often used to infer the origins of migratory animals based on the strong correlation between deuterium content of tissues and long-term patterns of precipitation. However, the extreme flood and drought dynamics of surface waters in prairie wetland systems could mask these expected correlations. We investigated H isotopic variability in an aquatic food web associated with Tree Swallows (Tachycineta bicolor) that rely heavily on wetland-derived aerial insects for food. We evaluated isotopic turnover and incorporation of environmental water into tissue, processes that could affect H isotopic composition. Wetland water and aquatic invertebrates showed intra- and interannual H isotopic variation mainly related to evaporation and the amount and timing of precipitation. Snails showed rapid turnover of tissue deuterium and a large contribution of environmental water to their tissues. Swallow feather deuterium (delta2Hf) was variable but did not clearly follow changes in any of the food web compartments measured. Instead, isotopic variability may have been driven by shifts in the type or relative amounts of grey consumed and types of wetlands used. Nevertheless, despite relatively high variance in delta2Hf, the majority of birds fell within the predicted range of delta2Hf for the study area, revealing that significant trophic averaging occurred. However, both (presumed) diet shifts and variable hydrological conditions have the potential to greatly increase variance that must be considered when assigning origins of migratory animals based on delta2H. PMID:23495640

  6. Isotope study of the groundwater of the Apodi Plateau

    International Nuclear Information System (INIS)

    Full text: The environmental isotopes oxygen-18 and deuterium, excellent natural tracers in hydrology, are used to characterize the groundwater stored in the Sedimentary Apodi Basin. They are originating from the Acu Sandstone Formation and from the limestone of the Jandaira Formation. These waters assist the needs from agricultural industry implanted on the top of the Apodi Plateau, responsible for the export of tropical horticulture products. This turns these waters a strategic reserve for the economic and social development of the area, and detailed knowledge of their storage and recharge conditions is necessary in order to maintain a sustainable exploration and an appropriate rational administration. With the objective of understanding the recharge mechanism and the interaction between the two aquifers, hydro chemical parameters, pH, and electric conductivity and isotopes oxygen-18 and deuterium were measured. Samples were collected in two periods, being one during the dry (set/09) and the other one at the beginning of the rainy period (jan/10). Values of δ18 (in per mil) range from -3.5 to -2.0 in the Jandaira limestone waters, whereas they have an average of only -4.5 in Acu sandstone. Thus Jandaira values indicate the presence of recent waters and the values below - 4.0 in Acu waters indicate the presence of paleowaters, waters that should be considered as strategic reserve. The relationships between the two isotopes measured in the dry and rainy periods are described respectively by the equations δD = 4.0δO18 - 10.5 and δD = 5.3δO18 - 1.3. Comparing them to the classical World Meteoric Water Line (δD = 8δO18 + 10, we identify that especially in the dry period evaporation and/or limestone dissolution play an important role. Electric conductivities of Jandaira waters range from 1000 to 3000μS/cm; waters from Acu sandstone are of lower salinity with a mean value of 500μS/cm. The relationship between the parameters oxygen-18, deuterium and electric

  7. The effect of site-specific isotopic substitutions on transport coefficients of liquid methanol

    International Nuclear Information System (INIS)

    A new approach is suggested for studying the nature of molecular transport in simple liquids, which makes use of site-specific isotopic substitutions. Its application represents the first systematic experimental study of a theoretically predicted correlation between transport coefficients in liquids and molecular moments of inertia. For this purpose, we have determined the viscosities and self-diffusion coefficients at 25 degree C of normal methanol and seven isotopically labeled methanol species: CH3OD, CD3OH, CD3OD, CH2DOH, CHD2OH, CHD2OD, and 13CH3OH. Except for 12C/13C substitution, the observed isotope effects are significantly larger than predicted by a square root of mass dependence, but are well correlated with the square roots of the moments of inertia. The results give strong evidence that translation--rotation coupling influences the transport processes in methanol, thus confirming earlier interpretations of isotope effects upon the transport in water

  8. Study on influencing factors for hydrogen isotopic exchange

    International Nuclear Information System (INIS)

    Background: Hydrogen-water catalytic exchange reaction offers an approach to hydrogen isotope separation, which can be applied in heavy water detritiation. Purpose: To optimize the operating condition for hydrogen-water catalytic exchange reaction, we analysed the influence of different factors on the transfer coefficient. Methods: In detail, the isotope exchange experiments of H-D system were carried out in a self-designed catalytic bed loaded with hydrophobic catalyst and hydrophilic packing with certain volume ratio. The experiments showed the changes of both the transfer coefficient and the pressure drop of column with the changing of the operational temperatures (29℃, 45℃, 60℃ and 75℃), the ratios of gas to liquid (0.58, 1.17, 2.65, 3.54) and the deuterium concentrations (5.05×10-3, 1.0144×10-2, 2.01×10-2). Results: Results showed that 45℃ is the optimal temperature for operating. The transfer coefficient increases with the increasing of the ratio of gas to liquid in the ranges of 0.58 to 1.17 and 2.65 to 3.56, while decreases with the deuterium concentration increases from 5.05×10-3 to 2.01×10-2. The pressure drop of column increases with increasing of gas flow rate. Conclusions: The experiment proves that the ratio of gas to liquid, the reaction temperature and the deuterium concentration are all important factors, which influence the transfer coefficient of deuterium obviously. The optimal operating condition for hydrogen-water catalytic exchange reaction are as follows: the temperature is 45℃, the ratio of gas to liquid is 3.56, and the deuterium concentration is 2.01×10-2. (authors)

  9. Stable isotope studies. Annual progress report, March 1, 1981-February 28, 1982

    International Nuclear Information System (INIS)

    Our studies during the year consisted of cryogenic measurements of vapor pressure isotope effects (VPIE) in CHF3, CH2F2, CH3F, and ammonia, interpretations of the results of the VPIE studies of CHF3 and CH3F by means of ab initio molecular orbital calculations and vibrational analyses, studies of nitrogen isotope fractionation by an exchange between nitric oxide and the liquid phase consisting of N2O3 and N2O4 under elevated pressures, an exploration of the concept of closed refluxer system for the Nitrox process for separating 15N using a Fe(II)/Fe(III) system as reducing agent for nitric acid and the electrolysis for regeneration of Fe(II), and a theoretical study of approximation of the zero-point energy and its isotopic differences developed on the basis of Lanczos' tau-method

  10. Study on nuclear structures of Te isotopes beyond N = 82 shell closure

    Science.gov (United States)

    Lee, Pilsoo; Lee, Chun Sik; Moon, Chang-Bum; Eurica Ribf-87 Collaboration Collaboration

    2016-03-01

    Tellurium which has two valence protons above the Z = 50 proton shell closure is well known for collective behavior in low-lying states. Therefore, Te isotopes are known to be a good test ground for studying nuclear collective modes but also the effect of neutron-proton interaction on the shell evolution with variation of neutron numbers owing to the valence protons above Z = 50 . For this reason Te isotopes always attract our attention, however, most available spectroscopic nuclear data of Te isotopes remains below N = 82 , and experimental data is severely limited above N = 82 . Meanwhile, recent study of 138Te by means of β- γ spectroscopy with fission fragments of 238U has provided us with new clues on excited states in 138Te, and the new experimental result has proposed new excited states that were unexpected in the previous theoretical studies. This study aims at understanding structural evolution in Te isotopes above N = 82 with respect to below N = 82 including the new data set available today. In this presentation we discuss the nuclear structures and effective interactions in Te isotopes above N = 82 based on the nuclear shell model and interacting boson approximations.

  11. Importance of the Lu-Hf isotopic system in studies of planetary chronology and chemical evolution

    Science.gov (United States)

    Patchett, P. J.

    1983-01-01

    The Lu-176-Hf-176 isotope method and its applications in earth sciences are discussed with regard to planetary-evolution studies. From new data on basalts from oceanic islands, Hf-176/Hf-177 and Nd-143/Nd-144 are found to display a single linear isotopic variation in the suboceanic mantle, whereas considerable divergences occur in Hf-176/Hf-177-Sr-87/Sr-86 and Nd-143/Nd-144-Sr87/Sr-86 diagrams. With the acquisition of further Hf-Sr-Nd isotopic data, these discordant Sr-87/Sr-86 relationships may allow a distinction between processes such as mantle metasomatism, influence of sea-water altered material in the magma source, or recycling of sediments into the mantle. The best quality Hf isotope data are obtained from granitoid or zircons, and are most suitable for studying ancient terrestrial Hf isotopic variations. Lu-Hf is shown to be a viable method for dating ancient terrestrial and extraterrestrial samples, but is unlikely to find wide application in pure chronological studies because it offers little advantage over existing methods.

  12. Design study of fuel circulating system using Pd alloy membrane isotope separation method

    International Nuclear Information System (INIS)

    It is expected that the method of permeating through Pd-alloy membrances is effective for isotope separation and the refining of fuel gas. In this paper, the design study of the Fuel Circulating System (FCS) using Pb-alloy membranes is described. The study is mainly focused on the main vacuum, fuel gas refining, isotope separating, and tritium containment systems. In the fuel gas refining system, impurities are effectively removed by using Pd-alloy membranes. For the isotope separation system, the diffusion method through Pd-alloy membranes was adopted. From the standpoint of the safety and economy, a three-stage tritium containment system was adopted to control tritium release to the environment as low as possible. The principal conclusion drawn from the design study was as follows. In the FCS, while cryogenic distillation method appears to be practicable, Pd-alloy membrane method is attractive for isotope separation and the refining of fuel gas. For a large amount of tritium inventory, handling and control technologies should be completed by the experimental evaluation and development of the components and materials used for the FCS. A three-stage containment system was adopted to control tritium release to environment as low as possible. Consideration to prevent tritium escape will be necessary for fuel gas refiners and isotope separators. (Kato, T.)

  13. Environmental isotope and hydrochemical study of the shallow and deep groundwater in the Azraq Basin, Jordan

    International Nuclear Information System (INIS)

    Since the country depends mostly on ground water resources especially for domestic water supply, investigation and management of the limited water resources takes importance and priority on governmental level as well as for the decision makers in the water Authority of Jordan. Azraq basin took importance in the whole water policy of the country, since the ground water abstraction for different water uses influences the natural environment of the Azraq Oasis. One of the aims of the study is to define the origin and source of recharge of AWSA water supply well field and the interrelationship between the Azraq depression and the situation in northern Azraq basin. Also quantitative and qualitative identification of the interrelationship between the upper and the deep aquifers become necessary. Many springs and wells in the Azraq area have been sampled for isotope analyses during the past 30 years by independent projects. The isotope analyses for the present project have been carried out by the Isotope Laboratory of the Water Authority of Jordan. This is existed within the frame work of the IAEA Regional Technical Cooperation Project entitled ''Isotope Hydrology in the Middle East''. Some hydrological and hydrogeological data from the Water Resources Studies Department of the Water Authority of Jordan have been used in the interpretation and evaluation. The overall evaluation of the environmental isotope data for both upper and deep aquifer systems in Azraq basin is presented in this study. (author). 7 refs, 18 figs, 3 tabs

  14. Study on plutonium isotopic analysis in environmental samples

    International Nuclear Information System (INIS)

    A method for determination of plutonium isotope ratio in environmental samples was investigated in our laboratory. Plutonium was separated with complex matrix and purified by using TEVA extraction chromatography resin, and determined by MC-ICP-MS. The elution of Pu from TEVA column was tested. Plutonium could be eluted from TEVA column effectively by 0.025mol·l-1 H2C2O4-0.15mol·l-1HNO3 or 10-2 mol·l-1 ascorbic acid- 0.2 mol·l-1HNO3. For one TEVA column, the decontamination factors of main environmental matrix , such as Na, K, Ca, Al, Fe, Mg, were between 104-105, and the concentration of total cation ions in the final elution was less than 10 μg·g-1, which could be determined by MC-ICP-MS directly. The decontamination of U, Th and Am was also examined, DFU/Pu=1.97x103, DFTh/Pu=7.19 x 104, DFAm/Pu=1.52x104 were obtained. The chemical recovery of plutonium during the whole process was ∼ 30%. Because of the tailing of 238U and the formation of 238UH+ while the determination of plutonium isotope by MS, it was not enough for the decontamination of uranium by using one TEVA column. A UTEVA column was needed before the solution loading in the TEVA resin. The decontamination factor of uranium could reach 1.33x106. The detection limit of Pu by MC-ICP-MS was about 2.5 fg·ml-1. The influence of U on the determination of plutonium isotope ratio was also examined. For the solution containing less than 1 ng·g-1 uranium, Aridus sample introduction system was adopted to improve the sensitivity. Meinhard PFA nebulizer was used for solutions of high uranium concentration (1- 500 ng·g-1). The results show that, the 238UH+/U+ is about 8.9x10-5 for the high content of uranium, and about 3.6x10-4 for the low content. According to the method mentioned above, two IAEA reference materials, IAEA-368 and SOIL-6 were analyzed. Purified Pu fractions were obtained by using UTEVA+TEVA extraction chromatography; 240Pu/239Pu were determined by MC-ICP-MS. The results were shown. Ocean

  15. Study on plutonium isotopic analysis in environmental samples

    International Nuclear Information System (INIS)

    A method for determination of plutonium isotope ratio in environmental samples was investigated in our laboratory. Plutonium was separated with complex matrix and purified by using TEVA extraction chromatography resin, and determined by MC-ICP-MS. The elution of Pu from TEVA column was tested. Plutonium could be eluted from TEVA column effectively by 0.025mol·l-1 H2C2O4-0.15mol·l-1HNO3 or 10-2 mol·l-1 ascorbic acid-0.2mol·l-1HNO3. For one TEVA column, the decontamination factors of main environmental matrix , such as Na, K, Ca, Al, Fe, Mg, were between 104-105, and the concentration of total cation ions in the final elution was less than 10 μg·g-1, which could be determined by MC-ICP-MS directly. The decontamination of U, Th and Am was also examined, DFU/Pu=1.97x103,DFTh/Pu=7.19x104,DFAm/Pu=1.52x104 were obtained. The chemical recovery of plutonium during the whole process was ∼30%. Because of the tailing of 238U and the formation of 238UH+ while the determination of plutonium isotope by MS, it was not enough for the decontamination of uranium by using one TEVA column. A UTEVA column was needed before the solution loading in the TEVA resin. The decontamination factor of uranium could reach 1.33x106. The detection limit of Pu by MC-ICP-MS was about 2.5 fg·ml-1. The influence of U on the determination of plutonium isotope ratio was also examined. For the solution containing less than 1 ng·g-1 uranium, Aridus sample introduction system was adopted to improve the sensitivity. Meinhard PFA nebulizer was used for solutions of high uranium concentration(1-500 ng·g-1). The results show that, the 238UH+/U+ is about 8.9x10-5 for the high content of uranium, and about 3.6x10-4 for the low content. According to the method mentioned above, two IAEA reference materials, IAEA-368 and SOIL-6 were analyzed. Purified Pu fractions were obtained by using UTEVA+TEVA extraction chromatography; 240Pu/239Pu were determined by MC-ICP-MS. The results were showed in table 1. Ocean

  16. Isotopes in environmental studies - Aquatic Forum 2004. Proceedings of an international conference. Unedited papers

    International Nuclear Information System (INIS)

    A better understanding of key processes in the aquatic environment, responsible for its future development and its protection, were at the forefront of the IAEA's International Conference on Isotopes in Environmental Studies - AQUATIC FORUM 2004 convened in Monaco from 25 to 29 October 2004, which was the most important gathering of the year of isotope environmental scientists. Over 320 experts from 60 IAEA Member States and 6 international organizations delivered 185 oral presentations in 6 plenary and 31 parallel sessions and made 130 poster presentations. The conference reviewed the present state of the art isotopic methods for investigation of the aquatic environment. The main conference subjects considered were: (i) behaviour, transport and distribution of isotopes in the aquatic environment; (ii) climate change studies using isotopic records in the marine environment; (iii) groundwater dynamics, modelling and management of freshwater sources; (iv) important global projects, such as WOCE, WOMARS, SHOTS, GEOTRACES; (v) joint IAEA-UNESCO submarine groundwater investigations in the Mediterranean Sea, the Southwest Atlantic and Pacific Oceans; (vi) new trends in radioecological investigations, concentrating on the protection of marine biota against radioactive contamination; (vii) transfers in analytical technologies from bulk analyses to particle and compound specific analyses of environmental samples; (viii) development of new isotopic techniques, such as AMS and ICPMS, and their successful applications in environmental studies; and many other exciting topics which were presented and discussed during the Conference. Four workshops were held simultaneously: - ATOMS-Med Workshop - development of a project proposal for oceanographic investigations in the Eastern Mediterranean. - El Nino - Research Co-ordination Meeting of the new IAEA Coordinated Research Project investigating climate change using isotopic records in the marine environment. - CELLAR Workshop

  17. The use of environmental isotopes on groundwater hydrology in the selected areas in Thailand

    International Nuclear Information System (INIS)

    A detailed environmental isotope investigation (using 0-18, H-2, H-3, C-14 and C-13 isotopes) has been carried out in a multi-layer aquifer system of the Chao-Phraya basin in Thailand. The main emphasis of the applied field research has been placed on the delineation of genesis of water and on studying the regional replenishment and flow characteristics of the groundwater in the lower Chao-Phraya basin (Bangkok Metropolitan Area). The results of isotope data gathered have been evaluated along with hydrochemical and basic hydrogeological data, to provide quantitative information on the replenishment characteristics of the groundwater and on the cause and processes involved in the increase of salinity being observed in the groundwater system of the Bangkok area. The report provides all the isotopic results and other relevant data together with interpretation and evaluation of the results. Refs, figs and tabs

  18. Progresses in the stable isotope studies of microbial processes associated with wetland methane production

    International Nuclear Information System (INIS)

    Methane emissions from wetlands play a key role in regulating global atmospheric methane concentration, so better understanding of microbial processes for the methane emission in wetlands is critical for developing process models and reducing uncertainty in global methane emission inventory. In this review, we describe basic microbial processes for wetland methane production and then demonstrate how stable isotope fractionation and stable isotope probing can be used to investigate the mechanisms underlying different methanogenic pathways and to quantify microbial species involved in wetland methane production. When applying stable isotope technique to calculate contributions of different pathways to the total methane production in various wetlands, the technical challenge is how to determine isotopic fractionation factors for the acetate derived methane production and carbon dioxide derived methane production. Although the application of stable isotope probing techniques to study the actual functions of different microbial organisms to methane production process is significantly superior to the traditional molecular biology method, the combination of these two technologies will be crucial for direct linking of the microbial community and functional structure with the corresponding metabolic functions, and provide new ideas for future studies. (authors)

  19. Strontium Isotope Study of Coal Untilization By-products Interacting with Environmental Waters

    Energy Technology Data Exchange (ETDEWEB)

    Spivak-Birndorf, Lev J; Stewart, Brian W; Capo, Rosemary C; Chapman, Elizabeth C; Schroeder, Karl T; Brubaker, Tonya M

    2011-09-01

    Sequential leaching experiments on coal utilization by-products (CUB) were coupled with chemical and strontium (Sr) isotopic analyses to better understand the influence of coal type and combustion processes on CUB properties and the release of elements during interaction with environmental waters during disposal. Class C fly ash tended to release the highest quantity of minor and trace elements—including alkaline earth elements, sodium, chromium, copper, manganese, lead, titanium, and zinc—during sequential extraction, with bottom ash yielding the lowest. Strontium isotope ratios ({sup 87}Sr/{sup 86}Sr) in bulk-CUB samples (total dissolution of CUB) are generally higher in class F ash than in class C ash. Bulk-CUB ratios appear to be controlled by the geologic source of the mineral matter in the feed coal, and by Sr added during desulfurization treatments. Leachates of the CUB generally have Sr isotope ratios that are different than the bulk value, demonstrating that Sr was not isotopically homogenized during combustion. Variations in the Sr isotopic composition of CUB leachates were correlated with mobility of several major and trace elements; the data suggest that arsenic and lead are held in phases that contain the more radiogenic (high-{sup 87}Sr/{sup 86}Sr) component. A changing Sr isotope ratio of CUB-interacting waters in a disposal environment could forecast the release of certain strongly bound elements of environmental concern. This study lays the groundwork for the application of Sr isotopes as an environmental tracer for CUB–water interaction.

  20. Isotopic and geochemical studies of fluid-rock interactions and the chemical evolution of the oceans

    Energy Technology Data Exchange (ETDEWEB)

    Derry, L.A.

    1989-01-01

    The isotopic compositions of Sr and Nd, and the abundances of rare earth elements (REE) are used to study various types of fluid-rock interactions in the Earth's crust. The isotopic compositions of Sr and Nd and REE patterns in marine chemical sediments of Precambrian age are used to estimate the relative importance of continental weathering versus submarine hydrothermal activity in determining the chemical mass balance of the Precambrian oceans. Major and trace element abundances and Sr and Nd isotopes are used to quantify the degree of interaction of a carbonatite fluid-magmatic system with felsic crust, and to constrain the isotopic characteristics of the mantle source region. The isotopic composition of Sr is reported from a well characterized sequence of Upper Proterozoic carbonates from Svalbard and east Greenland. A simple model of carbonate recycling and isotopic mass balance calculations illustrate that sedimentary recycling can have a strong influence on Sr in the oceans. REE patterns from Precambrian banded iron formations (BIFs) are very similar to modern metalliferous sediments, and imply that the overall REE pattern of Precambrian seawater was similar to today. The mantle-like {var epsilon}{sub Nd} values and positive Eu anomalies imply that the source of the REE in the BIFs was submarine hydrothermal activity. The implications of a large hydrothermal flux of reduced Fe on the redox controls of the Precambrian atmosphere are explored, and a testable hypothesis is developed. The mass balance of Eu in the oceans is affected by preferential scavenging at hydrothermal sites. Data from the Cherry Hill, CA mineralizing system imply a complex plumbing system and a long residence time for the water. Isotopic data from the Fen alkaline complex, Norway, define mixing trends between mantle derived magmas or magmatic fluids and old crust.

  1. Revisiting climate changes. Isotope studies open scientific windows to the past

    International Nuclear Information System (INIS)

    Earlier this year, scientists warned that 'an increasing body of observations gives a collective picture of a warming world and other changes in the climate system'. The conclusion came from the third assessment report of the Intergovernmental Panel on Climate Change (IPCC). Today, it is widely accepted that recent warning is largely a product of enhanced greenhouse gas concentrations in the atmosphere derived from post-industrial combustion of fossil fuels and biomass energy sources. However, great uncertainty remains regarding the causal relationships between specific parameters and climate phenomena, and regarding the impacts of climate change on the earth's water cycle. The science of climate change is dynamic. The IAEA contributes to studies via coordination of climate research, participation and support for international scientific programmes, and dissemination of isotope technology and applications. The third quadrennial scientific gathering on the use of isotopes for studying environmental change was held at the IAEA in Vienna 23-27 April 2001. The Conference - attended by 150 experts from 38 countries and seven international organizations - served as an important forum for presentation of results, discussion of ideas and concepts, establishment of international collaboration, and identification of avenues for future research. Selected highlights of issues discussed include: Isotopes are being used as validation tools for predicting impacts of deforestation of the Amazon Basin and for examining the past isotope signals of El Nino events; Isotope signatures in ice cores from low-latitude environments are showing similar temperature signals to polar ice cores,suggesting widespread (global) changes in the past; Isotopes are being used in the World Ocean Circulation Experiment to trace the movement, mixing and residence time of oceanic circulation patterns. Changes in ocean circulation are one of the most important factors controlling the variability of the

  2. Stable isotope studies of nicotine kinetics and bioavailability

    International Nuclear Information System (INIS)

    The stable isotope-labeled compound 3',3'-dideuteronicotine was used to investigate the disposition kinetics of nicotine in smokers, the systemic absorption of nicotine from cigarette smoke, and the bioavailability of nicotine ingested as oral capsules. Blood levels of labeled nicotine could be measured for 9 hours after a 30-minute intravenous infusion. Analysis of disposition kinetics in 10 healthy men revealed a multiexponential decline after the end of an infusion, with an elimination half-life averaging 203 minutes. This half-life was longer than that previously reported, indicating the presence of a shallow elimination phase. Plasma clearance averaged 14.6 ml/min/kg. The average intake of nicotine per cigarette was 2.29 mg. A cigarette smoke-monitoring system that directly measured particulate matter in smoke was evaluated in these subjects. Total particulate matter, number of puffs on the cigarette, total puff volume, and time of puffing correlated with the intake of nicotine from smoking. The oral bioavailability of nicotine averaged 44%. This bioavailability is higher than expected based on the systemic clearance of nicotine and suggests that there may be significant extrahepatic metabolism of nicotine

  3. Stable isotope study of thermal and other waters in Fiji

    International Nuclear Information System (INIS)

    The O-18/O-16, D/H ratios and chloride concentrations of 79 thermal spring, subsurface, and surface waters from the two main islands of Fiji have been measured to determine the origin of the thermal waters and the characteristics of the geothermal activity. The meteoric waters generally fall along the Meteoric Water Line with a slope of 8, and best fit a line of this slope with a delta D intercept of +13 per mill. The delta O-18/delta D ratios of the thermal waters indicate low magnitude subsurface temperatures and a negligible enrichment in O-18. In one coastal locality in which higher temperature conditions exist, up to 50% seawater is shown to be mixing within the system, probably at shallow depths. The isotopic characteristics of the thermal waters reflect those of the local meteoric water, indicating localised recharge and an essentially meteoric origin. The effects of prevailing wind conditions and topography of these islands cause a depletion of deuterium in both precipitation and surface meteoric water from windward to leeward coasts (auth)

  4. Isotopomer Spectral Analysis: Utilizing Nonlinear Models in Isotopic Flux Studies.

    Science.gov (United States)

    Kelleher, Joanne K; Nickol, Gary B

    2015-01-01

    We present the principles underlying the isotopomer spectral analysis (ISA) method for evaluating biosynthesis using stable isotopes. ISA addresses a classic conundrum encountered in the use of radioisotopes to estimate biosynthesis rates whereby the information available is insufficient to estimate biosynthesis. ISA overcomes this difficulty capitalizing on the additional information available from the mass isotopomer labeling profile of a polymer. ISA utilizes nonlinear regression to estimate the two unknown parameters of the model. A key parameter estimated by ISA represents the fractional contribution of the tracer to the precursor pool for the biosynthesis, D. By estimating D in cells synthesizing lipids, ISA quantifies the relative importance of two distinct pathways for flux of glutamine to lipid, reductive carboxylation, and glutaminolysis. ISA can also evaluate the competition between different metabolites, such as glucose and acetoacetate, as precursors for lipogenesis and thereby reveal regulatory properties of the biosynthesis pathway. The model is flexible and may be expanded to quantify sterol biosynthesis allowing tracer to enter the pathway at three different positions, acetyl CoA, acetoacetyl CoA, and mevalonate. The nonlinear properties of ISA provide a method of testing for the presence of gradients of precursor enrichment illustrated by in vivo sterol synthesis. A second ISA parameter provides the fraction of the polymer that is newly synthesized over the time course of the experiment. In summary, ISA is a flexible framework for developing models of polymerization biosynthesis providing insight into pools and pathway that are not easily quantified by other techniques. PMID:26358909

  5. Stable-isotope studies of groundwaters in southeastern New Mexico

    International Nuclear Information System (INIS)

    Oxygen-18/16 and deuterium/hydrogen ratio measurements have been made on groundwaters sampled according to specific field criteria applied during pump tests of the Rustler Formation in Nash Draw, a solution-subsidence valley west of the WIPP site in the northern Delaware Basin of southeastern New Mexico. Comparison of these data with similar measurements on other groundwaters from the northern Delaware Basin indicates two nonoverlapping populations of meteoric groundwaters. Most of the Rustler waters in Nash Draw and at the WIPP site and older waters from the eastern two-thirds of the Capitan Limestone constitute one population, while unconfined groundwaters originating as observable modern surface recharge to alluvium, the near-surface Rustler in southwestern Nash Draw, and the Capitan in the Guadalupe Mountains (Carlsbad Caverns) constitute the other. The isotopic distinction suggests that Rustler groundwater in most of Nash Draw and at the WIPP site is not receiving significant modern meteoric recharge. A likely explanation for this distinction is that meteoric recharge to most of the Rustler and Capitan took place in the geologic past under climatic conditions significantly different from the present. 25 refs., 4 figs., 2 tabs

  6. Isotope techniques in the study of the Guarani Aquifer

    International Nuclear Information System (INIS)

    The IAEA, through the Technical Cooperation Project (RLA8036), supports the application of isotope tools as part of a large international project which addresses a number of key questions in hydrolgeology and groundwater uses of the Guarani Aquifer. Groundwater constitutes around 95% of all the planet's fresh and liquid water. It is used by more than two billion people in the world and is considered as the greatest strategic reserve for the next decades. About 26% of the available freshwater in the world is in South America, and more than 50% of its population is supplied by groundwater. Low vulnerability to short climate variations places groundwater in a privileged position when societies' sustainability is evaluated. In spite of this importance, in many of our countries, groundwater resources have not received, nor receive, the attention deserved. During the last decade, the interest in South America about groundwater has grown but the few available management schemes operating in most countries are no longer adequate. As a result of a lack of adequate management schemes, ground pollution and inadequate well-head protection measures, some overexploitation (greater water extraction than the aquifer's potential) and pollution signs have been observed in some aquifers. If actions are not taken to ensure the preservation of these resources and correction measures are not adopted in critical areas, we will place at risk public and private water supply schemes, mainly in urban centres. The actions to be adopted will depend on the existing technical knowledge of the aquifers an on the countries' initiatives

  7. Isotope geochemistry and the study of habitability and life on other planets (Invited)

    Science.gov (United States)

    Eiler, J.

    2010-12-01

    The question of life on other planets might be solved by a remarkable discovery — a martian coquina, or perhaps a tentacle print on a distant landscape. But, until this happens, evidence for life and, more generally, habitability will use indirect geochemical arguments such as isotope thermometers and biomarkers (molecular, isotopic, and elemental fingerprints of biology)., Understanding this evidence will also demand a quantitative planetary history based on isotopic dating. Laboratory study of samples derived from Mars or other solar-system bodies will be a focus of geochemical investigations aimed at such assessments. Examples of how this will be done can be found in studies of the Precambrian geologic record and Martian meteorites. Debates regarding environmental conditions and biogenicity of minerals and organic matter are common in the study of such materials. These controversies derive from simple but refractory problems with the geochemical principles we employ: Indicators of metabolism can be mimicked by abiologic reactions; paleo-environmental proxies generally require an understanding of related geochemical cycles (e.g., the isotopic budget of water); and, though many organic molecules are unambiguous biomarkers, diagenesis can transform them into compounds that resemble products of abiogenic organic synthesis. If planetary sample return is to produce definitive geochemical constraints on habitability and biology, we will require either luck or a new class of geochemical tools that explicitly address these problems. The spatial distribution of rare isotopes within molecular structures, including ‘clumping’ and position-specific isotope effects, offer new geochemical tools that could provide such solutions. For example, even a simple molecule like acetic acid (C2H4O2) has more than 200 distinct isotopic configurations when spatial distribution of isotopes is considered, and the proportions of these could reflect formation temperature, the nature of

  8. Field ionization mass spectrometry (FIMS) applied to tracer studies and isotope dilution analysis

    International Nuclear Information System (INIS)

    The nonfragmenting nature of field ionization mass spectrometry makes it a preferred technique for the isotopic analysis of multilabeled organic compounds. The possibility of field ionization of nonvolatile thermolabile materials significantly extends the potential uses of this technique beyond those of conventional ionization methods. Multilabeled tracers may be studied in biological systems with a sensitivity comparable to that of radioactive tracers. Isotope dilution analysis may be performed reliably by this technique down to picogram levels. These techniques will be illustrated by a number of current studies using multilabeled metabolites and drugs. The scope and limitations of the methodology are discussed

  9. Study of short-lived tin isotopes with a laser ion source

    International Nuclear Information System (INIS)

    A chemically selective laser ion source based on resonance ionization of atoms in a hot cavity was applied for study of short-lived tin isotopes at the heavy ion accelerator UNILAC/GSI. Tin atoms were ionized by a three-step resonance laser excitation of an autoionizing state. Yields of fusion-produced 108Sn and 108In isotopes were compared with the plasma ion source FEBIAD-B3. The total efficiency of tin ionization was determined to be 8.5%, whilst the indium isobar ionization was suppressed by a factor of 12. An experimental run on study of decay properties of extremely neutron deficient isotopes 101-103Sn has been carried out

  10. A study of isotope ratio measurement by inductively coupled plasma mass spectrometry

    International Nuclear Information System (INIS)

    The measurement of isotopic ratios by inductively coupled plasma mass spectrometry (ICP-MS) has the benefits of ionising all metallic elements, simplifying sample preparation and reducing analysis time, when compared with thermal ionisation mass spectrometry (TIMS). However, the use of ICP-MS in isotopic ratio studies has been somewhat restricted by its failure to offer the precision and accuracy required by a variety of applications. The precision achievable by ICP-MS, typically 0.2 to 0.3% RSD, for isotopic ratios, has generally been regarded as being primarily limited by instrumental instability. An investigation of the sources of instrumental noise in ICP-MS has been undertaken, utilising noise spectral analysis as a diagnostic aid. Study of parametric variation upon noise production has identified the methods by which modulation of the ion signal occurs. Noise spectral analysis has allowed an understanding of the limitations imposed upon measurement precision by the various contributing noise sources to be established. (author)

  11. Isotope techniques in hydrological studies: application to Chacabuco-Polpaico basin

    International Nuclear Information System (INIS)

    A hydrogeological study was carried out in a small alluvial valley, 45 kms. north of Santiago, Chile. Although the main economical activity is the agriculture, the valley only has small seasonal rivers. The irrigation water comes from a near basin through a channel of about 100 kms. and from the ground water. The study include aspects like: pumping tests evaluations, well stratigraphy, potentiometric surface fluctuation, water chemistry, stable isotopes and water balances. Isotopes, oxygen-18 and deuterium were used to identify the origin of the ground water in different sections of the valley and the importance of the infiltration. Also experiences were made to evaluate the evaporation of a small damm, using isotopes and the classical water balance methods. (O.S.)

  12. Groundwater problems studies in the Thar desert, India, using isotope techniques

    International Nuclear Information System (INIS)

    In groundwater management, particularly in arid regions like western Rajasthan, it is important to know the presence of modern recharge and to estimate the recharge rate to avoid over-exploitation of the groundwater resource. Isotopes can help to identify modern recharge and to estimate recharge rate to the aquifer. If modern recharge is absent, groundwater dating using radiocarbon could help to identify old groundwater or paleowaters. A number of isotope studies carried out in arid zones (particularly in the Sahara) have shown that the deep groundwater is generally very old. From these studies it was concluded that episodic large scale recharge corresponding to humid phases or pluvials occurred in these arid areas. The paper reviews our experiences on the application of isotope techniques in understanding groundwater recharge process in and western Rajasthan

  13. Carbon monoxide isotope fractionation in the dust cloud Lynds 134

    International Nuclear Information System (INIS)

    Prior observations of isotopically substituted CO in Lynds 134 are used to discuss the spatial behavior of the [CO]/[13CO] abundance ratio as a function of visual extinction in the cloud. [CO]/[13CO] is determined from both LTE and non-LTE evaluations of the double ratio [13CO]/: C18O] by subsequent application of an assumed constant, terrestrial oxygen isotope ratio. It is found that [CO]/[13CO] is roughly terrestrial toward the central regions of L134 where A/sub ν/> or approx. =7 mag, and decreases in the cloud periphery where A/sub ν/ is lower. These results are in qualitative agreement with theoretical expectation for a low-temperature, chemically fractionated dark cloud, in which preferential 13CO enhancement is driven in low-extinction regions by the charge exchange 13C++12CO→12C+13CO. The impact of this result on previous studies of the carbon isotope ratio [12C]/[13C] in the sense interstellar medium is discussed

  14. Carbon abundances and isotope ratios in 70 bright M giants

    International Nuclear Information System (INIS)

    Approximate carbon abundances and 12C/13C isotope ratios are obtained for 70 M giant stars from intermediate-resolution spectrophotometry of the CO bands near 2.3 μm. A low mean carbon abundance ([C/H]=-0.64±0.29) is obtained, suggesting that standard mixing is insufficient to explain atmospheric abundances in M giants. HR 8795 appears to be exceptionally carbon deficient, and is worthy of further study as a possible weak G-band star descendant. (author)

  15. Study of the Lapindo mud burst origin in the 2007 - 2012 period using environmental isotopes

    International Nuclear Information System (INIS)

    Groundwater study around Lapindo mud burst, Sidoarjo, has been conducted from 2007 to 2012 using environmental isotopes. The objective of the study was to trace the groundwater origin through the isotopes variations. The study was conducted by collecting water samples annually from the center of the mud discharge and drilled wells around the area. For 14C analysis, the water and the mud need to be separated before collecting of the samples, however, samples for 18O and 2H isotopes analysis were directly put into 30 ml bottles. For comparison purposes, several samples were also collected from drilled wells owned by local ice factory at Porong about 1 km away from the center of mud burst. Stable isotopes 18O and 2H result shows that the variations of 8,33 ‰ to 12,49 ‰ for 18O and -8,9 ‰ to 1,8 ‰ for 2H. These variations indicated that the water around the center of the burst has interacted with magmatic process. Meanwhile, stable isotopes δ2H and δ18O variations of water samples collected from drilled wells indicated that the water is meteoric water. Another result found from this study was that water sample collected from Porong indicated similar origin with those collected from Pasuruan. The results of isotope 14C analysis in 2007 obtained that the age water at the center of the mud burst was found more than 40.000 years old and classified as connate water. From 2008 to 2012 period of sampling, the age has been dropped with variations from Modern to 20.000 years old which indicate the presence of groundwater or sea water contribution. (author)

  16. Valence neutrons' role in the collisions 13C+12C and 13C+13C

    International Nuclear Information System (INIS)

    The resonant behaviour is not limited to collisions between α-like nuclei: resonance structures have been observed in the direct channels for the 13C+12C and 13C+13C collisions; in the contrary, the resonances observed in the fusion channels are not so pronounced as in the 12C+12C case: the valence neutrons increase the number of reaction channels and the density of states in the states in the compound nuclei, the resonances are therefore 'washed out' and it is difficult to observe them experimentally

  17. C-13 relaxation time gradients in complexes of linear oligosaccharides and cyclodextrin

    International Nuclear Information System (INIS)

    A non-destructive method for sugar sequence determination is suggested using C-13 relaxation time gradients which are observable when the center of mass of the molecule is shifted by complexation with cyclodextrin. Quick and precise T1 measurements can be done in reasonable machine time because of the high solubility of simple methylated derivatives of cyclodextrin in water and because of the 1:1 host-guest ratio. A relaxation time gradient of more than 20% has been reported for a benzyl trisaccharide complex. (author)

  18. Experimental studies of the transfer phenomena of tritium in an isotope exchange column for tritium recovery

    International Nuclear Information System (INIS)

    In order to extract the tritium generated in the heavy water moderated power reactors we chosen the catalytic isotope exchange process in liquid phase combined with cryogenic distillation LPCE-CD. This paper presents the experimental studies of the catalytic isotope transfer of tritium. The catalytic isotope exchange process is realized in a column filled with successive layers of catalyst Pt/C/PTFE and B7 type ordered package of phosphorous bronze. The catalyst and the package are manufactured in our institute. The catalyst consists of 95.5 wt.% of PTFE, 4.1 wt. % of carbon and 0.40 wt. % of platinum and was in the form of Raschig rings with dimensions of 10 x 10 x 2 mm. The B7 type ordered package consists of a phosphorous bronze 4x1 wire mesh and the mesh dimension is 0.18 mm x 0.48 mm. The paper also presents the mathematical model which is used to evaluate the performance of this process. The mathematical model and the experimental data allowed the determination of two rate constants for isotope exchange process and for distillation process. By considering the values of these rate constants it is possible to improve the hydrophobic Pt catalyst and to design the H2/H2O isotopic exchange column package with this catalyst. (author)

  19. Study on determination of plutonium isotopes in soils from Lublin region (Poland)

    International Nuclear Information System (INIS)

    Plutonium isotopes were introduced to the environment mainly as a fallout from nuclear weapons tests carried out intensively in 1954 - 1963 and occasionally later. It was estimated that about 1.2·1016 Bq of 239,240Pu and about 8·10l4Bq of 238Pu was spread in the atmosphere. Another source of plutonium isotopes, which caused local contamination were liquid releases from nuclear facilities, fallout from nuclear-powered satellites burnt up in the atmosphere, accidents of airplanes carrying nuclear missiles or accidental releases such as from Chernobyl in 1986. The latter, which caused the most extensive contamination, especially in Europe, introduced to the atmosphere about 2·1014 Bq of 239,240Pu. Most of plutonium isotopes was spread in the stratosphere, from where it falls down continuously on the Earth surface. Region of Lublin (in eastern part of Poland) has not come yet within monitoring of soil contamination by alpha emitting isotopes like plutonium, while the large contaminations with Chernobyl originated radioisotopes were observed. In our Department we have taken up a study on determination of contamination level of soil by alpha emitting nuclides and, as a result of a cooperation with J. Stefan Institute in Ljubljana (Slovenia), we have developed methods for plutonium isotopes separation

  20. Crotonase-catalyzed β-elimination is concerted: A double isotope effect study

    International Nuclear Information System (INIS)

    Determining the sequence of bond cleavages, and consequently the nature of intermediates, in enzyme-catalyzed reactions is major goal of mechanistic enzymology. When significant primary isotope effects of V/K are observed for two different bond cleavages, both bonds may be broken in the same transition state or they can reflect two different transition states that are of nearly identical energy and consequently both are partially rate limiting. The observation of a solvent discrimination isotope effect determined from the relative incorporation of 2H from 50% D2O of 1.60±0.03, identical with the primary D(V/K), and the determination that the rate of exchange of the abstracted proton with solvent proceeds at less than 3% of the overall reaction rate also fail to provide evidence for a carbanion intermediate and are consistent with a concerted reaction. Identical primary D(V/K)s determined in H2O and D2O indicate that there is not a significant solvent isotope effect on C-O bond cleavage. The isotope ratios determined in these studies were performed by negative ion chemical ionization whole mass spectrometry of the pentafluorobenzyl esters, a new method whose validity is established by comparison with previously determined kinetic and equilibrium isotope effects

  1. Isotope effect studies of the pyruvate-dependent histidine decarboxylase from Lactobacillus 30a

    International Nuclear Information System (INIS)

    The decarboxylation of histidine by the pyruvate-dependent histidine decarboxylase of Lactobacillus 30 a shows a carbon isotope effect k12/k13 = 1.0334 +/- 0.0005 and a nitrogen isotope effect k14/k15 = 0.9799 +/- 0.0006 at pH 4.8, 370C. The carbon isotope effect is slightly increased by deuteriation of the substrate and slightly decreased in D2O. The observed nitrogen isotope effect indicates that the imine nitrogen in the substrate-Schiff base intermediate complex is ordinarily protonated, and the pH dependence of the carbon isotope effect indicates that both protonated and unprotonated forms of this intermediate are capable of undergoing decarboxylation. As with the pyridoxal 5'-phosphate dependent enzyme, Schiff base formation and decarboxylation are jointly rate-limiting, with the intermediate histidine-pyruvate Schiff base showing a decarboxylation/Schiff base hydrolysis ratio of 0.5-1.0 at pH 4.8. The decarboxylation transition state is more reactant-like for the pyruvate-dependent enzyme than for the pyridoxal 5'-phosphate dependent enzyme. These studies find no particular energetic or catalytic advantage to the use of pyridoxal 5'-phosphate over covalently bound pyruvate in catalysis of the decarboxylation of histidine

  2. Hydrogen and oxygen isotope studies of metamorphic fluid-rock interactions in the Dabie Mountains

    Institute of Scientific and Technical Information of China (English)

    傅斌; 郑永飞; 李一良; 肖益林; 龚冰

    1999-01-01

    Hydrogen and oxygen isotope studies were carried out on mineral separates from high to ultrahigh pressure metamorphic rocks at Huangzhen and Shuanghe in the eastern Dabie Mountains, East China. The δ 18O values of eelogites cover a wide range of-5‰ to+9‰, but the δD values of micas fall within a narrow range of -85‰ to -70‰. Both equilibrium and disequilibrium oxygen isotope fractionations were observed between quartz and the other minerals, with reversed fractionations between omphacite and garnet in some eclogite samples. The δ 18O values of -5‰ to -1‰ for some of the eclogites represent the oxygen isotope compositions of their protoliths which underwent meteoric water-rock interaction prior to plate subduction. The preservation of oxygen isotope heterogeneity in the eclogites implies a channelized flow of fluids during progressive metamorphism caused by rapid subduetion. Retrograde metamorphism has caused oxygen and hydrogen isotope disequilibria between some of the minerals, but the f

  3. Environmental isotope studies on groundwater from the crystalline bedrock in Finland

    International Nuclear Information System (INIS)

    Full text: Environmental isotope research on groundwater from crystalline bedrock in Finland is focused on: - investigations of coastal brackish and saline groundwater, - site investigations for nuclear waste disposal, and - a regional study of deep saline groundwater. Geochemical evolution of bedrock groundwater is evaluated on the basis of radioactive (3H, 14C) and stable (2H, 18O) isotope data, combined with chemical data, and topographic and tectonic implications of groundwater occurrence. In the coastal belt of Finland brackish and saline groundwater is trapped in fractures and shear zones, and exhibits distinct marine chemical and isotopic imprints. It represents relict seawater, mainly from the postglacial Litorina Sea phase. Inland, saline groundwater and brines occur in several diamond drill holes at depths of 300 to 1100 metres. The salinity of these waters is attributed predominantly to water-rock interaction. The uppermost water has meteoric oxygen-hydrogen isotopic compositions, whereas the most saline (Cl- some 20,000 mg/L) deep-seated groundwater plots above the global meteoric water line, like the Canadian Shield brines, indicating long residence time and low temperature equilibration with wall rocks. Geochemical and isotopic results from some localities demonstrate that the upper saline water cannot be attributed to simple mixing between fresh water and deep brines but that it was formed independently. (author)

  4. Isotopic study of water exchange between atmosphere and biosphere at Changa Manga site in Pakistan

    International Nuclear Information System (INIS)

    Study of water exchange between atmosphere and biosphere was initiated to understand the ties between these two spheres. Samples of leaves and stems of 23 woody plants along with soil from the surface and from the depth of 7 cm were collected from Changa Manga forest. Moisture content from these samples was extracted using the vacuum distillation method and analyzed for stable isotopes (/sup 18/O and /sup 2/H). Air moisture was also collected in the field. Isotopic data plotted long with the Local Meteoric Water Line (LMWL) indicates that /sup 18/O and /sup 2/H contents of moisture in the leaves of woody plants are higher than their respective stems. This behavior is due to the evaporative enrichment trend originating from the soil moisture in active root zone and also from the leaf surface. The stem samples did not show any significant variation in gamma /sup 18/O suggesting no significant evaporation from stems of big trees. Degree of enrichment of leave samples of woody plants indicated the species-specific effects in isotopes during transpiration. Pine and Eucalyptus leaves showed more variation in the isotopic contents as compared to other species. Temporal variations of /sup 18/O and /sup 2/H in the leaves indicated enriched isotopic values during hot and dry periods as compared to those during wet period (monsoon and winter rains) mainly due to higher transpiration rates at high temperature and low humidity. (orig./A.B.)

  5. Stable isotope studies. Annual progress report, March 1, 1980-February 28, 1981

    International Nuclear Information System (INIS)

    Vapor pressures of 12CHF3, 13CHF3, and 12CDF3 were measured between -147 and -600C. The normal isotope effect of deuterium with a positive slope and the inverse isotope effect of 13C with a negative slope in the plot of T 1n(P'/P) vs 1/T are simultaneously explanable only in terms of a blue-shift in the C-H stretching frequency upon condensation of fluoroform molecules. Vapor pressures of 12CH3F, 13CH3F, and 12CD3F were also measured between -141 and -600C. The deuterium effect is a normal isotope effect with a large positive slope. The 13C effect is an inverse isotope effect with a slightly positive slope. A nitrogen-15 exchange column based on the pressurized NO/N2O3 system was constructed. New refluxer designs were developed. Two FORTRAN programs have been written for studies of differential isotope effect

  6. Laboratory study of nitrate photolysis in Antarctic snow. II. Isotopic effects and wavelength dependence

    Energy Technology Data Exchange (ETDEWEB)

    Berhanu, Tesfaye A.; Erbland, Joseph; Savarino, Joël [Laboratoire de Glaciologie et Géophysique de l’Environnement, CNRS, F-38041 Grenoble (France); Univ. Grenoble Alpes, LGGE, F-38041 Grenoble (France); Meusinger, Carl; Johnson, Matthew S. [Copenhagen Center for Atmospheric Research (CCAR), Department of Chemistry, University of Copenhagen, Copenhagen (Denmark); Jost, Rémy [Laboratoire de Interdisciplinaire de Physique (LIPHY) Univ. de Grenoble, Grenoble (France); Bhattacharya, S. K. [Research Center for Environmental Changes, Academia Sinica, Nangang, Taipei 115, Taiwan (China)

    2014-06-28

    Atmospheric nitrate is preserved in Antarctic snow firn and ice. However, at low snow accumulation sites, post-depositional processes induced by sunlight obscure its interpretation. The goal of these studies (see also Paper I by Meusinger et al. [“Laboratory study of nitrate photolysis in Antarctic snow. I. Observed quantum yield, domain of photolysis, and secondary chemistry,” J. Chem. Phys. 140, 244305 (2014)]) is to characterize nitrate photochemistry and improve the interpretation of the nitrate ice core record. Naturally occurring stable isotopes in nitrate ({sup 15}N, {sup 17}O, and {sup 18}O) provide additional information concerning post-depositional processes. Here, we present results from studies of the wavelength-dependent isotope effects from photolysis of nitrate in a matrix of natural snow. Snow from Dome C, Antarctica was irradiated in selected wavelength regions using a Xe UV lamp and filters. The irradiated snow was sampled and analyzed for nitrate concentration and isotopic composition (δ{sup 15}N, δ{sup 18}O, and Δ{sup 17}O). From these measurements an average photolytic isotopic fractionation of {sup 15}ε = (−15 ± 1.2)‰ was found for broadband Xe lamp photolysis. These results are due in part to excitation of the intense absorption band of nitrate around 200 nm in addition to the weaker band centered at 305 nm followed by photodissociation. An experiment with a filter blocking wavelengths shorter than 320 nm, approximating the actinic flux spectrum at Dome C, yielded a photolytic isotopic fractionation of {sup 15}ε = (−47.9 ± 6.8)‰, in good agreement with fractionations determined by previous studies for the East Antarctic Plateau which range from −40 to −74.3‰. We describe a new semi-empirical zero point energy shift model used to derive the absorption cross sections of {sup 14}NO{sub 3}{sup −} and {sup 15}NO{sub 3}{sup −} in snow at a chosen temperature. The nitrogen isotopic fractionations obtained by applying

  7. Laboratory study of nitrate photolysis in Antarctic snow. II. Isotopic effects and wavelength dependence

    International Nuclear Information System (INIS)

    Atmospheric nitrate is preserved in Antarctic snow firn and ice. However, at low snow accumulation sites, post-depositional processes induced by sunlight obscure its interpretation. The goal of these studies (see also Paper I by Meusinger et al. [“Laboratory study of nitrate photolysis in Antarctic snow. I. Observed quantum yield, domain of photolysis, and secondary chemistry,” J. Chem. Phys. 140, 244305 (2014)]) is to characterize nitrate photochemistry and improve the interpretation of the nitrate ice core record. Naturally occurring stable isotopes in nitrate (15N, 17O, and 18O) provide additional information concerning post-depositional processes. Here, we present results from studies of the wavelength-dependent isotope effects from photolysis of nitrate in a matrix of natural snow. Snow from Dome C, Antarctica was irradiated in selected wavelength regions using a Xe UV lamp and filters. The irradiated snow was sampled and analyzed for nitrate concentration and isotopic composition (δ15N, δ18O, and Δ17O). From these measurements an average photolytic isotopic fractionation of 15ε = (−15 ± 1.2)‰ was found for broadband Xe lamp photolysis. These results are due in part to excitation of the intense absorption band of nitrate around 200 nm in addition to the weaker band centered at 305 nm followed by photodissociation. An experiment with a filter blocking wavelengths shorter than 320 nm, approximating the actinic flux spectrum at Dome C, yielded a photolytic isotopic fractionation of 15ε = (−47.9 ± 6.8)‰, in good agreement with fractionations determined by previous studies for the East Antarctic Plateau which range from −40 to −74.3‰. We describe a new semi-empirical zero point energy shift model used to derive the absorption cross sections of 14NO3− and 15NO3− in snow at a chosen temperature. The nitrogen isotopic fractionations obtained by applying this model under the experimental temperature as well as considering the shift in width

  8. Syntheses of C-13 and C-14-labeled versions of the investigational proteasome inhibitor MLN9708.

    Science.gov (United States)

    Plesescu, Mihaela; Elliott, Eric L; Li, Yuexian; Prakash, Shimoga R

    2013-01-01

    MLN9708 (ixazomib citrate) is an investigational, orally bioavailable proteasome inhibitor that is under development by Millennium in clinical studies in both hematologic and nonhematologic malignancies. The stable isotope-labeled MLN9708 was required for bio-analytical studies. [(13) C9 ]-MLN9708 (11) was synthesized in seven steps from the uniformly labeled [(13) C6 ]-1,4-dichlorobenzene (3) and [1-(13) C]-acetyl chloride. Because of the presence of two chlorine atoms and a boron atom, compound 6 was further reacted with [(13) C2 ]-glycine to provide an internal standard that is well separated from the parent compound during mass spectrometric analysis. The radiolabeled version was prepared to support metabolite profiling and whole body autoradiography studies in experimental animals. [(14) C]-MLN9708 (19) was synthesized in six steps from commercially available [(14) C]-barium carbonate. The key intermediate, [carboxyl-(14) C]-2,5-dichlorobenzoic acid (14), was prepared by selective lithiation of 1-bromo-2,5-dichlorobenzene (12) followed by carbonation with [(14) C]-barium carbonate. In preparation for a one-time human absorption, distribution, metabolism and excretion (ADME) study, the stability of [(14) C]-MLN9708 and its precursors were also evaluated. PMID:24285522

  9. Carbon-rich presolar grains from massive stars. Subsolar 12C/13C and 14N/15N ratios and the mystery of 15N

    CERN Document Server

    Pignatari, M; Hoppe, P; Jordan, C J; Gibson, B K; Trappitsch, R; Herwig, F; Fryer, C; Hirschi, R; Timmes, F X

    2015-01-01

    Carbon-rich grains with isotopic anomalies compared to the Sun are found in primitive meteorites. They were made by stars, and carry the original stellar nucleosynthesis signature. Silicon carbide grains of Type X and C, and low-density graphites condensed in the ejecta of core-collapse supernovae. We present a new set of models for the explosive He shell and compare them with the grains showing 12C/13C and 14N/15N ratios lower than solar. In the stellar progenitor H was ingested into the He shell and not fully destroyed before the explosion. Different explosion energies and H concentrations are considered. If the SN shock hits the He-shell region with some H still present, the models can reproduce the C and N isotopic signatures in C-rich grains. Hot-CNO cycle isotopic signatures are obtained, including a large production of 13C and 15N. The short-lived radionuclides 22Na and 26Al are increased by orders of magnitude. The production of radiogenic 22Ne from the decay of 22Na in the He shell might solve the pu...

  10. Isotopic Studies of O-O Bond Formation During Water Oxidation (SISGR)

    Energy Technology Data Exchange (ETDEWEB)

    Roth, Justine P.

    2015-03-03

    Isotopic Studies of O-O Bond Formation During Water Oxidation (SISGR) Research during the project period focused primarily on mechanisms of water oxidation by structurally defined transition metal complexes. Competitive oxygen isotope fractionation of water, mediated by oxidized precursors or reduced catalysts together with ceric, Ce(IV), ammonium nitrate in aqueous media, afforded oxygen-18 kinetic isotope effects (O-18 KIEs). Measurement, calculation, and interpretation of O-18 KIEs, described in the accompanying report has important ramifications for the production of electricity and solar hydrogen (as fuel). The catalysis division of BES has acknowledged that understanding mechanisms of transition metal catalyzed water oxidation has major ramifications, potentially leading to transformation of the global economy and natural environment in years to come. Yet, because of program restructuring and decreased availability of funds, it was recommended that the Solar Photochemistry sub-division of BES would be a more appropriate parent program for support of continued research.

  11. Study of 242‑248Cm isotopes in the projected shell model framework

    Science.gov (United States)

    Sadiq, Saiqa; Devi, Rani; Khosa, S. K.

    2016-04-01

    The projected shell model framework is employed to study the band spectra in 242‑248Cm isotopes. The present calculations reproduce the available experimental data on the yrast bands. Besides this, B(E2) transition probabilities of even-even Cm isotopes have also been calculated. The low spin states of yrast band are seen to arise purely from zero-quasi-particle (o-qp) intrinsic states whereas the high spin states have multi-quasi-particle structure. For the odd-neutron (odd-N) isotopes, the calculated results qualitatively reproduce the available data on ground and lowest excited state bands for 243,245Cm. However, for 247Cm the negative-parity ground state band is in reasonable agreement with the experimental data.

  12. An Experimental Study of Oxygen Isotope Fractionation in the Quartz—Wolframite—Water System

    Institute of Scientific and Technical Information of China (English)

    张理刚; 刘敬秀; 等

    1993-01-01

    Oxygen isotope fractionation was experimentally studied in the quartz-wolframite-water systemf rom 200 to 420℃.The starting wolframite was synthexized in aqueous solutions of Na2WOR·2H2O+FeCl2·4H2O or MnCl2·4H2O.The starting solutions range in salinity from 0 to 10 equivalent wt.% NaCl.Experiments were conducted in a gold-lined stainless steel autoclave,with filling degrees of about 50%.The results showed no significant difference in dquilibrium isotope fractionation between water and wolframite,ferberite and huebnerite at the same temperature(310℃).The equilibrium oxygen isotope fractionation factors of wolframite and water tend to be equal with increasing temperature above 370℃.but to increase significantly with decreasing temperature below 370℃.

  13. Application of stable isotopes to the NMR conformational study of peptides and membrane proteins

    International Nuclear Information System (INIS)

    The nuclear magnetic resonance spectral analysis of the lipid-peptide complexes generally necessitates isotopic enrichment, specifically or not, of the lipidic or peptidic partner. The isotope labelling depends on the membrane model and the associated NMR techniques: high resolution 1H NMR of peptides or proteins in the presence of per-deuterated phospholipidic micells, high resolution (micells) or ''solid'' type 2H NMR of the lipid partner, ''solid'' type NMR (15N, 13C) of the peptide partner in a bi-layer. Application examples are given: utilization of stable isotopes for NMR study of lipopeptide structure and dynamic, of folding-up and functional linking at the annexines membrane interface, and of phospholipid conformation and dynamics in the lipids-ions-peptides interactions. 3 figs

  14. A systematical study of neutron-rich Zr isotopes by the projected shell model

    International Nuclear Information System (INIS)

    To understand the structure of neutron-rich nuclei and to validate the existing theoretical model for the exotic mass region, we study systematically strongly-deformed, neutron-rich even-even and odd-mass Zr isotopes with neutron number 61-66. With the projected shell model, the known experimental data are reproduced and some low-lying side-bands are predicted. The influence of the high-jh11/2 neutron orbital and the g9/2 proton orbital on the structure properties is investigated. For even-even isotopes, the structure of multi-quasiparticle bands is analyzed and some properties of the yrast line are described in detail. For odd-neutron isotopes, the discussion is focused on the excited single-particle configurations. Our predictions may help future experiments with identification of band structures in the very neutron-rich nuclei.

  15. Lithium isotopic separation: preliminary studies; Separacao isotopica de litio: estudos preliminares

    Energy Technology Data Exchange (ETDEWEB)

    Macedo, Sandra Helena Goulart de

    1998-07-01

    In order to get the separation of natural isotopes of lithium by electrolytic amalgamation, an electrolytic cell with a confined mercury cathode was used to obtain data for the design of a separation stage. The initial work was followed by the design of a moving mercury cathode electrolytic cell and three experiments with six batches stages were performed for the determination of the elementary separation factor. The value obtained, 1.053, was ill agreement: with the specialized literature. It was verified in all experiments that the lithium - 6 isotope concentrated in the amalgam phase and that the lithium - 7 isotope concentrated in the aqueous phase. A stainless-steel cathode for the decomposition of the lithium amalgam and the selective desamalgamation were also studied. In view of the results obtained, a five stages continuous scheme was proposed. (author)

  16. Trace contaminants of agriculture, fisheries and food with particular reference to isotope studies

    International Nuclear Information System (INIS)

    Growing world population, industrilization and intensification of agricultural and fisheries practices have greatly increased the need during recent decades to protect the resources concerned, and the quality of food and agricultural environment. These trends have also resulted in a growing range of trace contaminants and excessive nutrient problems of agriculture and fisheries. Isotopic tracer and nuclear analytical techniques are powerful and often unique tools for the study and control of the problems, especially in relation to trace elements, nutrients and contaminants. In addition to the conventional use of radioactive and stable isotopes as tracers there appears to be considerable scope for the use of environmental or natural isotope ratio techniques and the use of labelled reagents and substrates as monitoring tools. Representative applications are described. (author)

  17. Isotopic studies of the late Archean plutonic rocks of the Wind River Range, Wyoming.

    Science.gov (United States)

    Stuckless, J.S.; Hedge, C.E.; Worl, R.G.; Simmons, K.R.; Nkomo, I.T.; Wenner, D.B.

    1985-01-01

    Two late Archaean intrusive events were documented in the Wind River Range by isotopic studies of the Rb-Sr and U-Th-Pb systems in whole-rock samples and the U-Pb systematics for zircon. An age of approx 2630(20) m.y. for the Louis Lake batholith and apparent ages of 2504(40) to 2575(50) m.y. for the Bear Ears pluton were obtained. Post-magmatic hydrothermal events approximately Tertiary in age, lowered delta 18O values and disturbed parent-daughter relationships in most of the isotopic systems investigated. The two intrusive units apparently were derived from different protoliths. Initial isotopic ratios and petrochemistry for the Louis Lake batholith are consistent with an early Archaean trondhjemitic to tonalitic source. The protolith for the Bear Ears pluton must have been subjected to high-grade metamorphism that caused loss of Rb and U prior to magma generation. -L.C.H.

  18. Studies on treatment methods of the safeguards swipe samples for uranium isotope ratio measurement

    International Nuclear Information System (INIS)

    In the environmental sampling and analyses for safeguards, an accurate isotope ratio of uranium at trace levels is required for detection of undeclared nuclear activities. Currently, swipe (smear) samples are being taken by IAEA from nuclear facilities. The amount of uranium collected on the cotton swipe is expected to be in the wide range including the order of nano-gram or less. In order to measure the isotope ratios by ICP-MS, we have studied sample preparation procedures for the trace amount of uranium. Elements causing spectroscopic and non-spectroscopic interferences in ICP-MS measurement were sufficiently removed by anion-exchange of hydrochloric acid media. The uranium contamination introduced throughout the process the sample preparation was below 10 pg uranium per sample. The applicability of the treatment process for uranium isotope measurement up to 100 pico-grams was proposed. (author)

  19. Water resources in the Sahel. Hydrogeological and hydrological studies in West Africa by isotopic techniques. Statement of accounts of studies carried out in the framework of the project RAF/8/012: Isotopic hydrology in Sahelian countries

    International Nuclear Information System (INIS)

    International Atomic Energy Agency (IAEA) supports various projects on isotopic applications for environmental studies. This document contains papers presented on the use of isotopic analysis for hydrological studies in Sahel region of Africa. All the papers in this document are in French with English title and abstract. Refs, figs and tabs

  20. Isotopic study of the aquifer in the Tulum and Ullum-Zonda Valleys, San Juan, Argentina

    International Nuclear Information System (INIS)

    An isotopic and hydrochemical study on groundwater from Ullum-Zonda and Tulum Valleys, San Juan province, Argentina, has been performed. Recharge areas and the different water types feeding the basin groundwater were determined. Gross isotopic differences among the San Juan river, originated in the high Cordillera de los Andes (δ18O = -16 per mille), rainwater over the surrounding hills (δ18O = -7 per mille) and the more positive local precipitation favoured this characterization. Also 14C content of twelve groundwater samples are presented. The interpretation of these results is discussed. (author). 9 refs, 3 figs, 2 tabs

  1. Study of solid-state isotopic exchange of hydrogen in L-alanine

    International Nuclear Information System (INIS)

    The solid-state isotopic exchange of L-Ala with the spillover tritium activated on Rh(Pd) supported catalysts and the reactivity of hydrogen at C(2) and C(3) carbon atoms of L-Ala were studied using tritium NMR. The activation energy of the catalyzed isotopic exchange was measured. Ab initio calculations of the reaction of hydrogen exchange in the alanine molecule with H3O+ ion were carried out. The mechanism and transition states of this reaction were proposed. 22 refs.; 4 figs.; 4 tabs

  2. Study of asymmetric fission yield behavior from neutron-deficient Hg isotope

    Energy Technology Data Exchange (ETDEWEB)

    Perkasa, Y. S. [Department of Physics, Sunan Gunung Djati State Islamic University Bandung, Jl. A.H Nasution No. 105 Cibiru, Bandung (Indonesia); Waris, A., E-mail: awaris@fi.itb.ac.id; Kurniadi, R., E-mail: awaris@fi.itb.ac.id; Su' ud, Z., E-mail: awaris@fi.itb.ac.id [Nuclear Physics and Biophysics Research Division, Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesa No. 10 Bandung 40132 (Indonesia)

    2014-09-30

    A study of asymmetric fission yield behavior from a neutron-deficient Hg isotope has been conducted. The fission yield calculation of the neutron-deficient Hg isotope using Brownian Metropolis shape had showed unusual result at decreasing energy. In this paper, this interesting feature will be validated by using nine degree of scission shapes parameterization from Brosa model that had been implemented in TALYS nuclear reaction code. This validation is intended to show agreement between both model and the experiment result. The expected result from these models considered to be different due to dynamical properties that implemented in both models.

  3. International Symposium on Isotopes in Hydrology, Marine Ecosystems, and Climate Change Studies. Presentations

    International Nuclear Information System (INIS)

    Human activities have had a far-reaching impact on the aquatic environments - both marine and freshwater systems. The protection of these systems against further deterioration and the promotion of sustainable use are vital. In order to deepen understanding about the main processes affecting the present situation, as well as possible developments in the future, further investigation is required. The oceans play a major role in climate change, for example, and ocean acidification by increased CO2 release is one major threat to the world's oceans. Isotope methods can play a critical role in identifying and quantifying key processes within aquatic environments. Addressing the problems of global water resources has become a matter of urgency. Water resources are subject to multiple pressures for various reasons, including increasing populations, climate change, rising food and energy costs, the global economic crisis and pollutant loading. Isotope hydrology provides the unique and critical tools required to address complex water problems and helps managers and policy makers understand the closely intertwined relationship between water resources and the various pressures affecting them, as well as the issue of sustainability. The symposium will be an important forum for the exchange of knowledge on the present state of marine and freshwater environments, use of isotopes in water resources investigations and management, and climate change studies. The meeting will involve leading scientists in the field of climate change and hydrology, as well as representatives from other United Nations bodies and international organizations that focus on climate change and other important environmental issues. TOPICS: The role of isotopes in understanding and modelling climate change, marine ecosystems and the water cycle; Carbon dioxide sequestration and related aspects of the carbon cycle, such as ocean acidification; Isotopes in groundwater flow modelling for large aquifers

  4. Utilization of Tritium and Carbon-14 in Studies of Isotope Effects

    International Nuclear Information System (INIS)

    The utility of tritium in organic research has been augmented by the development of a simple method for determining C14 and tritium in the same sample. The non-volatile, radioactive material, in a film that is 'infinitely thick' to tritium radiation, is counted in a windowless, gas-fiow proportional counter; the film is then re-counted when covered with a screen that stops all radiation from tritium but allows a fraction of that from C14 to pass. By introduction of one isotope at a point removed from the reaction centre, an isotope effect for the other can be determined from changes in the tritium-C14 ratio in the reactant and/or products as the reaction proceeds. Carriers of reactant, products or derivatives can be added at any point to facilitate isolation, because the analytical method depends primarily on the tritium-C14 ratio. Methods for utilizing the double-label technique will be illustrated by a study of isotope effects in the oxidation of the penultimate carbon of certain labelled polyols with Acetobacter suboxydans. Six D-mannitols position-labelled either with C14 or with tritium at C1, C2 or C3 were prepared. For these, isotope effects (k*/k) of 0.93, 0.23, and 0.71, respectively, were found with C14 at C2, tritium at C2, and tritium at C3; no detectable isotope effects were found for the remaining Dmannitols. In the oxidation of position-labelled D-glucitols, an isotope effect of 0.24 was found for tritium at C5; no detectable effect was found for either C14 or tritium at C1. The techniques are suitable for studying a variety of chemical and biological reactions. (author)

  5. Isotopes in Hydrology, Marine Ecosystems and Climate Change Studies. Vol. I. Proceedings of an International Symposium

    International Nuclear Information System (INIS)

    Humanity is facing many water related challenges, including access to safe water, pollution of continental and coastal waters and ocean acidification, as well as the growing impact of climate change on the hydrological cycle. Many countries are confronted by increasingly stressed water resources due to rapidly growing populations, increasing agricultural and energy production demands, industrial development, and pollution. The greatest issues of the 21st century, including competition for resources and possible related conflicts, may well focus on the role of water in food and energy security. For more than 50 years, the IAEA has played a key role in advancing and promoting the development and use of isotope techniques to address global environmental issues, such as water resources assessment and management, the study of marine ecosystems, and more recently the impact of climate change. This symposium was jointly organized by theWater Resources Programme and IAEA Environment Laboratories to commemorate the 50th anniversary of the establishment of the IAEA laboratory in the P rincipality of Monaco, and represented the 13th edition of the quadrennial symposium on isotope hydrology and water resources management, which has been regularly organized by the IAEA since 1963. The main objectives of the symposium were to review the state of the art in isotope hydrology, the use of isotopes in the study of climatic systems and in marine ecosystems and to outline recent developments in the application of isotope techniques, as well as to identify future trends and developments for research and applications. The contributions submitted by the authors are included in two volumes of proceedings with editorial corrections. These proceedings are intended to serve as an aid for those using isotopes for applied problems in hydrology as well as for the research community

  6. Isotope aided studies of atmospheric carbon dioxide and other greenhouse gases. Phase II

    International Nuclear Information System (INIS)

    The substantial increase in atmospheric greenhouse gas concentrations and their role in global warming have become major concerns of world governments. Application of isotope techniques to label sources and sinks of CO2 and other greenhouse gases has emerged as a potentially powerful method for reducing uncertainties in the global CO2 budgets and for tracing pathways and interaction of terrestrial, oceanic, and atmospheric pools of carbon. As with CO2 concentration measurements, meaningful integration of isotopes in global models requires careful attention to quality assurance, quality control and inter-comparability of measurements made by a number of networks and laboratories. To support improvements in isotope measurement capabilities, the IAEA began implementing Co-ordinated Research Projects (CRPs) in 1992. The first project, entitled Isotope Variations of Carbon Dioxide and other Trace Gases in the Atmosphere, was implemented from 1992 to 1994. A significant contribution was made towards a better understanding of the global carbon cycle and especially of the sources and sinks of carbon with data on the 14C and 13C content of atmospheric CO2, pointing to a better understanding of the problem of the 'missing sink' in the global carbon cycle. Important methodological developments in the field of high precision stable isotope mass spectrometry and improved data acquisition procedures emerged from work carried out within the framework of this programme. The development of pressurized gas standards and planning for an associated interlaboratory calibration were initiated. Due to the good progress and long standing nature of the required work a second CRP was initiated and implemented from 1996 to 1999. It was entitled Isotope aided Studies of Atmospheric Carbon Dioxide and Other Trace Gases - Phase II, to document the close relationship of both programmes. This publication provides an overview of the scientific outcomes of the studies conducted within Phase II of

  7. Isotopes in Hydrology, Marine Ecosystems and Climate Change Studies, Vol. 2. Proceedings of the International Symposium

    International Nuclear Information System (INIS)

    Humanity is facing many water related challenges, including access to safe water, pollution of continental and coastal waters and ocean acidification, as well as the growing impact of climate change on the hydrological cycle. Many countries are confronted by increasingly stressed water resources due to rapidly growing populations, increasing agricultural and energy production demands, industrial development, and pollution. The greatest issues of the 21st century, including competition for resources and possible related conflicts, may well focus on the role of water in food and energy security. For more than 50 years, the IAEA has played a key role in advancing and promoting the development and use of isotope techniques to address global environmental issues, such as water resources assessment and management, the study of marine ecosystems, and more recently the impact of climate change. This symposium was jointly organized by the Water Resources Programme and IAEA Environment Laboratories to commemorate the 50th anniversary of the establishment of the IAEA laboratory in the Principality of Monaco, and represented the 13th edition of the quadrennial symposium on isotope hydrology and water resources management, which has been regularly organized by the IAEA since 1963. The main objectives of the symposium were to review the state of the art in isotope hydrology, the use of isotopes in the study of climatic systems and in marine ecosystems and to outline recent developments in the application of isotope techniques, as well as to identify future trends and developments for research and applications. The contributions submitted by the authors are included in two volumes of proceedings with editorial corrections. These proceedings are intended to serve as an aid for those using isotopes for applied problems in hydrology as well as for the research community

  8. Kinetic and metabolic isotope effects in coral skeletal carbon isotopes: A re-evaluation using experimental coral bleaching as a case study

    Science.gov (United States)

    Schoepf, Verena; Levas, Stephen J.; Rodrigues, Lisa J.; McBride, Michael O.; Aschaffenburg, Matthew D.; Matsui, Yohei; Warner, Mark E.; Hughes, Adam D.; Grottoli, Andréa G.

    2014-12-01

    Coral skeletal δ13C can be a paleo-climate proxy for light levels (i.e., cloud cover and seasonality) and for photosynthesis to respiration (P/R) ratios. The usefulness of coral δ13C as a proxy depends on metabolic isotope effects (related to changes in photosynthesis) being the dominant influence on skeletal δ13C. However, it is also influenced by kinetic isotope effects (related to calcification rate) which can overpower metabolic isotope effects and thus compromise the use of coral skeletal δ13C as a proxy. Heikoop et al. (2000) proposed a simple data correction to remove kinetic isotope effects from coral skeletal δ13C, as well as an equation to calculate P/R ratios from coral isotopes. However, despite having been used by other researchers, the data correction has never been directly tested, and isotope-based P/R ratios have never been compared to P/R ratios measured using respirometry. Experimental coral bleaching represents a unique environmental scenario to test this because bleaching produces large physiological responses that influence both metabolic and kinetic isotope effects in corals. Here, we tested the δ13C correction and the P/R calculation using three Pacific and three Caribbean coral species from controlled temperature-induced bleaching experiments where both the stable isotopes and the physiological variables that cause isotopic fractionation (i.e., photosynthesis, respiration, and calcification) were simultaneously measured. We show for the first time that the data correction proposed by Heikoop et al. (2000) does not effectively remove kinetic effects in the coral species studied here, and did not improve the metabolic signal of bleached and non-bleached corals. In addition, isotope-based P/R ratios were in poor agreement with measured P/R ratios, even when the data correction was applied. This suggests that additional factors influence δ13C and δ18O, which are not accounted for by the data correction. We therefore recommend that the

  9. Oxygen isotopic composition of mammal bones as a new tool for studying ratios of paleoenvironmental water and paleoclimates

    International Nuclear Information System (INIS)

    The purpose of this study is to try to establish quantitative relationships between the average oxygen isotopic composition of local meteoric water, the oxygen isotopic composition of mammal body water and the oxygen isotopic composition of phosphate in mammal bones. These relationships, after calibration of the method on living specimens, would allow quantitative paleoclimatological research based on the measurement of delta18O(PO43-) of fossil mammal bones

  10. C-12/C-13 and O-16/O-18 ratios in the atmosphere of Venus from high-resolution 10-micron spectroscopy

    International Nuclear Information System (INIS)

    High-resolution observations of the thermal emission spectrum of Venus have been recorded in the 10.5-micron region, and these have led to the detection of several lines from the nu(3) - nu(1) bands of C-13O2 and C-12O-16O-18, as well as from the weak nu(3)+nu(2) - nu(1)+nu(2) band of C-12O2. The results obtained characterize the cloud top levels of Venus' atmosphere, at about 66 km; the derived ratios should be able to represent global values on Venus. These determinations are in agreement with in situ Pioneer Venus and Venera atmospheric composition measurements. It is demonstrated that important isotopic ratios are obtainable with ground-based spectroscopy. 26 references

  11. Isotopic study of mercury sources and transfer between a freshwater lake and adjacent forest food web

    International Nuclear Information System (INIS)

    Studies of monomethylmercury (MMHg) sources and biogeochemical pathways have been extensive in aquatic ecosystems, but limited in forest ecosystems. Increasing evidence suggests that there is significant mercury (Hg) exchange between aquatic and forest ecosystems. We use Hg stable isotope ratios (δ202Hg and Δ199Hg) to investigate the relative importance of MMHg sources and assess Hg transfer pathways between Douglas Lake and adjacent forests located at the University of Michigan Biological Station, USA. We characterize Hg isotopic compositions of basal resources and use linear regression of % MMHg versus δ202Hg and Δ199Hg to estimate Hg isotope values for inorganic mercury (IHg) and MMHg in the aquatic and adjacent forest food webs. In the aquatic ecosystem, we found that lake sediment represents a mixture of IHg pools deposited via watershed runoff and precipitation. The δ202Hg and Δ199Hg values estimated for IHg are consistent with other studies that measured forest floor in temperate forests. The Δ199Hg value estimated for MMHg in the aquatic food web indicates that MMHg is subjected to ~ 20% photochemical degradation prior to bioaccumulation. In the forest ecosystem, we found a significant negative relationship between total Hg and δ202Hg and Δ199Hg of soil collected at multiple distances from the lakeshore and lake sediment. This suggests that IHg input from watershed runoff provides an important Hg transfer pathway between the forest and aquatic ecosystems. We measured Δ199Hg values for high trophic level insects and compared these insects at multiple distances perpendicular to the lake shoreline. The Δ199Hg values correspond to the % canopy cover suggesting that forest MMHg is subjected to varying extents of photochemical degradation and the extent may be controlled by sunlight. Our study demonstrates that the use of Hg isotopes adds important new insight into the relative importance of MMHg sources and complex Hg transfer pathways across

  12. Isotopic study of mercury sources and transfer between a freshwater lake and adjacent forest food web

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Sae Yun, E-mail: saeyunk@umich.edu [Department of Earth and Environmental Sciences, University of Michigan, 1100 N. University Ave, Ann Arbor, MI 48109 (United States); Blum, Joel D. [Department of Earth and Environmental Sciences, University of Michigan, 1100 N. University Ave, Ann Arbor, MI 48109 (United States); Department of Ecology and Evolutionary Biology, University of Michigan, 830 N. University Ave, Ann Arbor, MI 48109 (United States); Nadelhoffer, Knute J. [Department of Ecology and Evolutionary Biology, University of Michigan, 830 N. University Ave, Ann Arbor, MI 48109 (United States); Timothy Dvonch, J. [Department of Environmental Health Sciences, University of Michigan, 1415 Washington Heights, Ann Arbor, MI 48109 (United States); Tsui, Martin Tsz-Ki [Department of Biology, University of North Carolina at Greensboro, 321 McIver Street, Greensboro, NC 27402 (United States)

    2015-11-01

    Studies of monomethylmercury (MMHg) sources and biogeochemical pathways have been extensive in aquatic ecosystems, but limited in forest ecosystems. Increasing evidence suggests that there is significant mercury (Hg) exchange between aquatic and forest ecosystems. We use Hg stable isotope ratios (δ{sup 202}Hg and Δ{sup 199}Hg) to investigate the relative importance of MMHg sources and assess Hg transfer pathways between Douglas Lake and adjacent forests located at the University of Michigan Biological Station, USA. We characterize Hg isotopic compositions of basal resources and use linear regression of % MMHg versus δ{sup 202}Hg and Δ{sup 199}Hg to estimate Hg isotope values for inorganic mercury (IHg) and MMHg in the aquatic and adjacent forest food webs. In the aquatic ecosystem, we found that lake sediment represents a mixture of IHg pools deposited via watershed runoff and precipitation. The δ{sup 202}Hg and Δ{sup 199}Hg values estimated for IHg are consistent with other studies that measured forest floor in temperate forests. The Δ{sup 199}Hg value estimated for MMHg in the aquatic food web indicates that MMHg is subjected to ~ 20% photochemical degradation prior to bioaccumulation. In the forest ecosystem, we found a significant negative relationship between total Hg and δ{sup 202}Hg and Δ{sup 199}Hg of soil collected at multiple distances from the lakeshore and lake sediment. This suggests that IHg input from watershed runoff provides an important Hg transfer pathway between the forest and aquatic ecosystems. We measured Δ{sup 199}Hg values for high trophic level insects and compared these insects at multiple distances perpendicular to the lake shoreline. The Δ{sup 199}Hg values correspond to the % canopy cover suggesting that forest MMHg is subjected to varying extents of photochemical degradation and the extent may be controlled by sunlight. Our study demonstrates that the use of Hg isotopes adds important new insight into the relative

  13. CNONa and 12C/13C in giants of 10 open clusters

    CERN Document Server

    Smiljanic, R; North, P; Barbuy, B; Charbonnel, C; Mowlavi, N

    2008-01-01

    Evolved low-mass stars with a large range in metallicity bear signatures of a non-standard mixing event in their surface abundances of Li, C, N, and in their 12C/13C ratio. A Na overabundance has also been reported in some giants of open clusters but remains debated. Recently, the cause of the extra-mixing has been attributed to thermohaline convection that should take place after the RGB bump for low mass stars and on the early-AGB for more massive objects. In order to track the occurrence of this process over a large mass range, we derive in a homogeneous way the abundances of C, N, O, and Na, as well as the 12C/13C ratio in a sample of 31 giants of 10 open clusters with turn-off masses from 1.7 to 3.1 Msun. A group of first ascent red giants with M/Msun $\\leq$ 2.5 exhibits smaller [N/C] ratios than those measured in clump giants of the same mass range, suggesting an additional increase of the [N/C] ratio after the first dredge-up. The sodium abundances corrected from NLTE are found to be about solar. [Na/F...

  14. A Study of the Molecular Cloud S64 with Multiple Lines of CO Isotopes

    Institute of Scientific and Technical Information of China (English)

    Lei Zhu; Yue-Fang Wu; Yue Wei

    2006-01-01

    We report on a study of the molecular cloud S64 with observations at millimeter wavelengths of multiple molecular lines of CO isotopes. A weak outflow is found, and its physical parameters are estimated. The departure of the core of S64 from the S64 HⅡ region indicates that there are still other star formation activities in that region.

  15. Study of isotopic desequilibrium of natural radioactive series in granitic environment: Pluton of El Berrocal (Toledo)

    International Nuclear Information System (INIS)

    This report summarizes the work funded by European Communities with contract '' The Berrocal project: characterization and validation of natural radionuclide migration processes under real conditions in a fissured granitic environment''. The author takes into account the following aspects in his study: isotope of natural radionuclides, sampling methods, analytic methodology and geological characteristics of the area

  16. Isotope Fractionation in Methane Reactions Studied by Gas Chromatography and Liquid Scintillation

    DEFF Research Database (Denmark)

    Andersen, Bertel Lohmann; Bidoglio, G.; Leip, A.;

    1997-01-01

    Determination of C-14-marked methane by gas chromatography and liquid scintillation counting is shown to be useful in studies of isotope effects. Data on the specific activity is used to separate the contributions of (CH4)-C-14, and (CH4)-C-12 to the gas-chromatographic peak area. As an application...

  17. Isotopic studies of beach rock carbonates from Konkan, central west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Kumar, B.; Rajamanickam, G.V.; Gujar, A.R.

    .7% (PDB) and delta sup(18)O signatures lie in a narrow range of +27.5 to +28.6% (SMOW), respectively. Isotopic data obtained in this study show that cementation of beach rock carbonates might have taken place in a shallow vadose zone. The large variations...

  18. You Are What You Eat: Mass spectrometry in paediatric kinetic studies using stable isotopes

    NARCIS (Netherlands)

    H. Schierbeek (Henk)

    2009-01-01

    textabstractAn overview will be presented about applications of stable isotopes in paediatric research. Mass spectrometry has proven to be an essential tool for unravelling kinetic studies in a large range of different research disciplines related to intestinal diseases, obesities, severe cerebral p

  19. Thin layer activation analysis of α induced reactions for surface wear studies in some natural isotopes

    International Nuclear Information System (INIS)

    The thin layer activation technique is widely used to study surface wear and erosion by employing medium energy, light charged particle accelerators in the micrometer range. In the present work, TLA technique has been explored using gamma spectroscopy for a large number of reactions in several isotopes, which may be of interest for the reactor technology

  20. Carbon, nitrogen, magnesium, silicon, and titanium isotopic compositions of single interstellar silicon carbide grains from the Murchison carbonaceous chondrite

    Science.gov (United States)

    Hoppe, Peter; Amari, Sachiko; Zinner, Ernst; Ireland, Trevor; Lewis, Roy S.

    1994-01-01

    Seven hundred and twenty SiC grains from the Murchison CM2 chondrite, ranging in size from 1 to 10 micrometers, were analyzed by ion microprobe mass spectrometry for their C-isotopic compositions. Subsets of the grains were also analyzed for N (450 grains), Si (183 grains), Mg (179 grains), and Ti (28 grains) isotopes. These results are compared with previous measurements on 41 larger SiC grains (up to 15 x 26 micrometers) from a different sample of Murchison analyzed by Virag et al. (1992) and Ireland, Zinner, & Amari (1991a). All grains of the present study are isotopically anomalous with C-12/C-13 ratios ranging from 0.022 to 28.4 x solar, N-14/N-15 ratios from 0.046 to 30 x solar, Si-29/Si-28 from 0.54 to 1.20 x solar, Si-30/Si-28 from 0.42 to 1.14 x solar, Ti-49/Ti-48 from 0.96 to 1.95 x solar, and Ti-50/Ti-48 from 0.94 to 1.39 x solar. Many grains have large Mg-26 excesses from the decay of Al-26 with inferred Al-26/Al-27 ratios ranging up to 0.61, or 12,200 x the ratio of 5 x 10(exp -5) inferred for the early solar system. Several groups can be distinguished among the SiC grains. Most of the grains have C-13 and N-14 excesses, and their Si isotopic compositions (mostly excesses in Si-29 and Si-30) plot close to a slope 1.34 line on a Delta Si-29/Si-28 versus Delta Si-30/Si-28 three-isotope plot. Grains with small C-12/C-13 ratios (less than 10) tend to have smaller or no N-14 excesses and high Al-26/Al-27 ratios (up to 0.01). Grains with C-12/C-13 greater than 150 fall into two groups: grains X have N-15 excesses and Si-29 and Si-30 deficits and the highest (0.1 to 0.6) Al-26/Al-27 ratios; grains Y have N-14 excesses and plot on a slope 0.35 line on a Si three-isotope plot. In addition, large SiC grains of the Virag et al. (1992) study fall into three-distinct clusters according to their C-, Si-, and Ti-isotopic compositions. The isotopic diversity of the grains and the clustering of their isotopic compositions imply distinct and multiple stellar sources

  1. Evaporation from the shallow Lake Massaciuccoli (Tuscany, Italy) studied using stable isotopes and evaporation pan data

    Science.gov (United States)

    Baneschi, I.; Gonfiantini, R.; Guidi, M.

    2009-04-01

    Oxygen and hydrogen isotope variations monitored in Lake Massaciuccoli (7 km2, 2 m deep, seasonally variable water level) during summer 2008, were compared with those observed in a Class A evaporation pan (diameter 120.6 cm, depth 25.4 cm) placed on the lake eastern shore. Air temperature, pressure, relative humidity, wind speed and direction, solar radiation, water temperature in the lake and the pan were also measured. The pluviometer indicated that no precipitation occurred during the study period. The pan was initially filled with groundwater up to the level of 19.2 cm (219 L), depleted in heavy isotopes with respect to tha lake water. Sodium chloride was added up to the concentration of 1 g×L-1, which is assumed do not affect significantly the evaporation rate till the water volume is reduced to less than 10 %. The Cl- concentration was used to provide an estimation of the evaporated water fraction, in addition to the micrometer measuring the water level variations. The pan water was sampled every 2-3 days and Cl- and stable isotopes determined. The set of stable isotope and evaporation data enabled us to compute the parameters governing the evaporation process and the isotopic exchanges with the atmospheric moisture, according to the procedure proposed by Gonfiantini (1986). The values were applied to test three working hypotheses of water balance of Lake Massaciuccoli: (i) surface inflow and outflow of liquid water are negligible and only evaporation is important; (ii) the inflow is negligible and outflow and evaporation are both significant; (iii) the three terms of balance are all important but the losses by evaporation and outflow exceed inflow (as the lake water level was decreasing). Water exchanges with groundwater are considered negligible. The best agreement between lake and pan data was obtained with the second hypothesis, for which the fraction of water removed by evaporation was estimated to be about 40 % ot he total water losses. This residual

  2. Application of stable isotopes (18O, D) to study the provenience of mineral waters from some locations of Romania

    International Nuclear Information System (INIS)

    The isotopic study (18O, D) of mineral waters from some locations (Bucovina, Covasna, Tusnad and Someseni) in Romania was carried out in a tentative to identify their origin. The investigations of waters from Bucovina, Covasna and Someseni (Springs No.1, 2, and 15) indicates the meteoric provenience, having the deuterium content of meteoric water, but shifted to higher 18O content. This 18O shift is the result of isotopic exchange of the water oxi gen with the rocks oxygen in its trajectory to discharge. The Spring No. 8 waters from Someseni Spa and Tusnad waters present the water isotopic content of mixed deep water with shallower meteoric water having heavier isotopic (D, 18O) content. The Spring No.3 waters from Someseni Spa present the springtime isotopic pulse, like a Becas brook, with water depletion in D and 18O isotopes proving pollution with surrounding snow water. (authors)

  3. An isotopic study of nitrate pollution of groundwater in Victoria, Australia

    International Nuclear Information System (INIS)

    Nitrate in groundwater can be a hard to human and animal health and contribute to the development of algal blooms and subsequent eutrophication of wetlands. Its presence is widespread throughout Australia and its levels overall appear to be increasing. A variety of sources of nitrate contamination of groundwater are known. These include nitrogen fixing plants, termites, animal wastes, industrial wastes, domestic wastes, sewage and fertilizers. In Victoria, nitrate-rich groundwaters have been reported from a number of localities, some of which include Colac, Nepean Peninsula, Shepparton, Deer Park, Benalla and Winchelsea. A multi-isotope method was developed to determine the probable source of pollution in these localities. Changes in the natural abundance ratio of the stable isotopes of nitrogen, 14N and 15N, and the differences in the isotopic ratios (15N/14N) of nitrate from various sources, form the basis of the N-isotope technique for source identification. Differences in the isotopic ratios of oxygen (18O/16O) and hydrogen (D/H) of polluted and unpolluted waters form the basis for the oxygen and hydrogen isotope technique to investigate pollution problems of groundwater. Sites which included clover, industrial wastes, animal and human wastes and fertilized sources, were selected after reviewing existing databases on nitrate concentration, earlier reports and access to a suitable network of bores for collecting reliable samples. The nitrate concentration ranged from less than 1 mg/L to in excess of 22.0 mg/L, whilst ammonium levels in most samples were less than 1 mg/L. The δ15N values of the various source types ranged from 8.8 to 19.0 per mill (pastures). The δ18O and δD data indicate seawater incursion in the coastal areas of the Nepean Peninsular. The results agree with published data on similar sources from elsewhere in the world, and indicate the potential use of this methodology in groundwater pollution studies in Australia

  4. Automated data extraction from in situ protein stable isotope probing studies

    Energy Technology Data Exchange (ETDEWEB)

    Slysz, Gordon W.; Steinke, Laurey A.; Ward, David M.; Klatt, Christian G.; Clauss, Therese RW; Purvine, Samuel O.; Payne, Samuel H.; Anderson, Gordon A.; Smith, Richard D.; Lipton, Mary S.

    2014-01-27

    Protein stable isotope probing (protein-SIP) has strong potential for revealing key metabolizing taxa in complex microbial communities. While most protein-SIP work to date has been performed under controlled laboratory conditions to allow extensive isotope labeling of the target organism, a key application will be in situ studies of microbial communities under conditions that result in small degrees of partial labeling. One hurdle restricting large scale in situ protein-SIP studies is the lack of algorithms and software for automated data processing of the massive data sets resulting from such studies. In response, we developed Stable Isotope Probing Protein Extraction Resources software (SIPPER) and applied it for large scale extraction and visualization of data from short term (3 h) protein-SIP experiments performed in situ on Yellowstone phototrophic bacterial mats. Several metrics incorporated into the software allow it to support exhaustive analysis of the complex composite isotopic envelope observed as a result of low amounts of partial label incorporation. SIPPER also enables the detection of labeled molecular species without the need for any prior identification.

  5. Bronze Age volcanic event recorded in stalagmites by combined isotope and trace element studies.

    Science.gov (United States)

    Siklósy, Zoltán; Demény, Attila; Vennemann, Torsten W; Pilet, Sebastien; Kramers, Jan; Leél-Ossy, Szabolcs; Bondár, Mária; Shen, Chuan-Chou; Hegner, Ernst

    2009-03-01

    Stable isotope analyses of speleothems (carbonate deposits formed in caves) have been widely used to reconstruct paleoenvironmental conditions. Recent improvements in geochemical techniques have enabled us to analyze climate-influenced deposits at high temporal resolution so that hitherto unrecognized environmental conditions may be identified. Stable H, C and O isotope analyses on carbonate and inclusion water have been combined with multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) age dating and laser-ablation ICP-MS trace element analyses on a stalagmite from southern Hungary. The study reveals significant changes in chemical and isotopic compositions of the speleothem between approx. 3800 and 3500 years BP ('Before Present') indicating coupled changes in the temperature and precipitation regime under which the speleothem formed. Stable isotopic and trace element correlations within this time period correlate with similar studies of stalagmites of comparable age from the Alpine-Mediterranean region. Our studies suggest that traces of deposition of volcanic dust, possibly related to the Thera eruption of Santorini (Greece) ca. 1650 BC (approximately 3650 BP), and environmental changes can be detected at a distance of several thousand kilometers. PMID:19219896

  6. Determination of recharge and evolutionary study in new wells at Berlin geothermal field using isotopes

    International Nuclear Information System (INIS)

    CEL have been made a preliminary study at Berlin geothermal field in order to estimate the recharge area. The results using isotopic data since 1996 to date shows an average altitude of 1350 masl. This value is in agreement with hydrological and geological studies, which correspond to an infiltration zone located around the Berlin-Tecapa complex. Isotopic composition from Laguna de Alegria (LA) located in the same complex and Rio Lempa located 12 km away from the field shows that there is not relation with the recharge of the Berlin geothermal field. Also, an evolutionary study of the geothermal wells shows three definite groups: new wells, production wells and reinjection wells. Isotopic composition in recently drilled wells is changing with time, showing more depleted values than production wells in which isotopic composition is seated in the range δ18O = -3.5 per mille to δ18O = -3.9 per mille and δD=-42 per mille to δD = -45 per mille. It suggest new wells still have a mixture of geothermal water and water introduced along the drilling. Reinjection wells seems to have not impact over production wells, at least with the available information. Monitoring is still on. (author)

  7. Shape coexistence in the lightest Tl isotopes studied by laser spectroscopy

    CERN Multimedia

    Herfurth, F; Antalic, S; Darby, I G; Venhart, M; Flanagan, K; Veselsky, M; Blaum, K; Radulov, D P; Beck, D; Kowalska, M; Schwarz, S; Chapman, R; Diriken, J V J; Lane, J; Rosenbusch, M

    This proposal aims at atomic spectroscopy studies of the very neutron-deficient isotopes $^{178-187}$Tl, at and far beyond the region of the neutron mid-shell at N=104, in which shape coexistence phenomena were investigated so far by particle and $\\gamma$-ray spectroscopy methods only. Our motivation for this proposal is as follows : \\\\\\\\ -These studies will provide direct data on magnetic dipole moment, spin, charge radii and deformations of these isotopes. The results will form a stringent test for our current understanding of the shape coexistence phenomena in the vicinity of the neutron mid-shell at N=104, where the relevant effects are expected to be the strongest (cf.shape staggering in the isotopes $^{181,183,185}$Hg). \\\\-The knowledge of the structure (configuration, spin, deformation) and whether one or two $\\beta$-decaying isomers are present in the parent isotopes $^{178,180,182}$Tl are crucial for understanding of the results of our recent studies of $\\beta$-delayed fission in the lightest thalli...

  8. Theoretical and isotope effect studies on cytochrome P-450 mediated aromatic oxidation

    International Nuclear Information System (INIS)

    Both theoretical and experimental approaches were used to probe the mechanism of cytochrome P-450 mediated aromatic oxidation. The theoretical studies used semiempirical molecular orbital calculations (MNDO) to model possible addition-rearrangement pathways and to clarify the role of epoxide intermediates during phenol formation. Both biradical and protonated cationic pathways leading to epoxides, ketones, and phenols were characterized for a series of substituted benzenes and naphthalene. The heats of formation and other thermodynamic properties of the geometry optimized products, intermediate, and transition states provided free energies of activation and allowed the calculation of kinetic isotope effects. The results of this study indicated that biradical pathways show little or no substituent effects and the order or reaction rates is epoxide > ketone > phenol. The cationic pathways show marked substituent effects and the order of reaction rates is reversed with phenol > ketone > epoxide. The experimental studies involved the measurement of isotope effects associated with the metabolism of a series of deuterated chlorobenzenes. Positive isotope effects were observed for the meta hydroxylation of 3,5-2H2-,2,4,6-2H3-, and 2H5-chlorobenzenes, whereas inverse isotope effects were measured for the ortho and para hydroxylation of 2,4,6-2H3-chlorobenzene

  9. Pb isotopic study on soils from Domizio-Flegreo Littoral area, Napoli, Italy

    Science.gov (United States)

    Grezzi, G.; Ayuso, R. A.; Lima, A.; Albanese, S.; de Vivo, B.

    2009-04-01

    The Domizio - Flegreo Littoral area, together with the Agro Aversano area, are part of a Site of National Interest for pollution assessment. This area is located along the north coastal zone of the Campania region (Italy) and has an extension of about 855 Km2. We analyzed soils for heavy metal content in order to study and discriminate the impact of natural and anthropogenic sources. We collected 292 soil surface samples (5-15 cm depth) and produced maps showing the distribution of heavy metals in the soils. On the basis of the geographic distribution of heavy metals, 9 soil profiles were also collected for detailed examination (1 meter from surface). From each soil profile, we collected 10 soil samples (1/10 cm) in the urban and suburban areas of the littoral area. Also, we collected 8 groundwater samples likely associated with the soils. Pb isotope compositions of these soils and waters help to constrain the impact of anthropogenic and natural components on the soil profiles. Possible anthropogenic end-members include pesticides used in the area. Lead isotope compositions of soils known to contain anomalously high values of heavy metals were measured in order to determine the sources of the Pb and, by inference, sources of other metals that are likely to share similar geochemical behaviour in the surface environment (e.g., As). Acid-leach compositions of the soils represent Pb that is adsorbed to mineral surfaces, whereas residue compositions may reflect bedrock. Labile Pb (acid-leach fractions) from the soils shows a range in compositions of 207Pb/206Pb = 0.8275 to 0.8486, and 208Pb/206Pb = 2.0488 to 2.0873. The isotope values vary and decrease with depth. The Pb isotope ratios obtained on groundwater samples range from about 207Pb/206Pb = 0.8516 to 0.8636, 208Pb/206Pb = 2.0706 to 2.1064. The Pb isotope ratios in the soil profiles and groundwater are generally consistent with multiple sources that include anthropogenic Pb. Surface soil samples from Giugliano

  10. Surfactant phosphatidylcholine metabolism in preterm infants studied with stable isotopes

    NARCIS (Netherlands)

    J.E.H. Bunt (Jan Erik)

    2000-01-01

    textabstractAIM OF THE STUDIES 1. To develop and use a novel method to study surfactant metabolism in preterm and older infants. (chapters 3 and 4). 2. To study endogenous surfactant synthesis in relation to prenatal glucocorticosteroids. (chapters 5 and 6). 3. To study the influence of surfactant t

  11. Surfactant phosphatidylcholine metabolism in preterm infants studied with stable isotopes

    OpenAIRE

    Bunt, Jan Erik

    2000-01-01

    textabstractAIM OF THE STUDIES 1. To develop and use a novel method to study surfactant metabolism in preterm and older infants. (chapters 3 and 4). 2. To study endogenous surfactant synthesis in relation to prenatal glucocorticosteroids. (chapters 5 and 6). 3. To study the influence of surfactant therapy on endogenous surfactant metabolism. (chapters 7 and 8). 4. To study surfactant composition and concentration after surfactant therapy. (chapter 8).

  12. Trophic relationships in a tropical stream food web assessed by stable isotope analysis

    OpenAIRE

    Coat, Sophie; Monti, Dominique; Bouchon, Claude; Lepoint, Gilles

    2009-01-01

    1. Stable isotope analysis, coupled with dietary data from the literature, was used to investigate trophic patterns of freshwater fauna in a tropical stream food web (Guadeloupe, French West Indies). 2. Primary producers (biofilm, algae and plant detritus of terrestrial origin) showed distinct delta C-13 signatures, which allowed for a powerful discrimination of carbon sources. Both autochthonous (C-13-enriched signatures) and allochthonous (C-13-depleted signatures) resources enter the food ...

  13. Effect of microtopography on isotopic composition of methane in porewater and efflux at a boreal peatland

    Energy Technology Data Exchange (ETDEWEB)

    Dorodnikov, M.; Wilmking, M. [Greifswald Univ. (Georgia). Inst. of Botany and Landscape Ecology; Marushchak, M.; Biasi, C. [Univ. of Eastern Finland, Kuopio (Finland). Dept. of Environmental Science, Bioteknia 2], E-mail: maxim.dorodnikov@uef.fi

    2013-09-01

    The application of stable isotopes is an approach to identify pathways of methanogenesis, methane (CH{sub 4}) oxidation and transport in peatlands. We measured the stable C isotopic characteristics ({delta}C-13) of CH{sub 4} in peat profiles below hummocks, lawns and hollows of a Finnish mire to study the patterns of CH{sub 4} turnover. Porewater CH{sub 4} concentrations ([CH{sub 4}]; at 0.5-2 m) increased with depth below all microforms. Emissions of CH{sub 4} from hummocks were the lowest, and increased with the increasing water-saturated zone, being {approx}10 times higher from hollows. Thus, the microtopography of the peatland did not affect the porewater [CH{sub 4}] in the water-saturated part of the peat profile, but the CH{sub 4} emissions were affected due to differences in the oxidative potential of the microforms. There was a decrease in {delta}C-13-CH{sub 4} with depth below all microforms indicating dominance of CO{sub 2}-reduction over acetate cleavage pathway of methanogenesis at deep peat layers. However, estimated potential portions of transported CH{sub 4} comprised 50%-70% of the {delta}C-13-CH{sub 4} enrichment on microforms at the 0.5-m depth, hereby masking the acetate cleavage pathway of methanogenesis. Stable C composition ({delta}C-13) of CH{sub 4} proved to be a suitable (but not sufficient) tool to differentiate between types of methanogenesis in continuously water-saturated layers below microforms of a peatland. Combined flux-based and multi-isotopic approaches are needed to better understand the CH{sub 4} turnover process. (orig.)

  14. Position-Specific and Clumped Stable Isotope Studies: Comparison of the Urey and Path-Integral Approaches for Carbon Dioxide, Nitrous Oxide, Methane, and Propane

    OpenAIRE

    Webb, Michael A.; Miller, Thomas F.

    2013-01-01

    We combine path-integral Monte Carlo methods with high-quality potential energy surfaces to compute equilibrium isotope effects in a variety of systems relevant to ‘clumped’ isotope analysis and isotope geochemistry, including CO_2, N_2O, methane, and propane. Through a systematic study of heavy-atom isotope-exchange reactions, we quantify and analyze errors that arise in the widely used Urey model for predicting equilibrium constants of isotope-exchange reactions using reduced partition func...

  15. Zinc homeostasis in man: studies using a new stable isotope-dilution technique

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, M.J.; Jones, D.A.; Edwards, R.H.T. (University Coll., London (UK). The Rayne Inst.); Swainbank, I.G.; Coleman, M.L. (Institute of Geological Sciences, London (UK))

    1984-03-01

    A new method has been developed for the study of zinc metabolism in man using the stable isotope /sup 67/Zn. The technique involves intravenous infusion of the isotope followed by measurements of the plasma and faecal enrichments over a period of days. A procedure for the analysis of Zn isotopes in plasma and faeces is described which requires the separation of Zn from other elements using the chelator dithizone before analysis by thermal-ionization mass spectrometry. The stable isotope technique has been used in conjunction with a metabolic balance study to obtain measurements of Zn absorption and gastrointestinal secretion in a normal subject. Preliminary measurements of the size of the exchangeable pool of Zn have been made as have estimates of the rates of plasma and whole-body Zn turnover. Following an increase in dietary Zn the body appeared to respond in two ways. The gastrointestinal secretion of Zn increased immediately, but only by a relatively small amount. The absorption of Zn initially increased in proportion to the increase in dietary levels but then decreased within 4 d by an amount sufficient to restore Zn balance.

  16. Use of environmental isotopes in hydrogeological studies in Kedah and Perlis, Malaysia

    International Nuclear Information System (INIS)

    A preliminary study of the isotope hydrology of the Kedah and Perlis area was undertaken under the RCA programme. This project is an attempt at elucidating the mechanism of recharge, origin, area of recharge and dating of groundwater system in the area. The results show that all groundwater samples in the area vary within a narrow range for 180 (-7.58 to -5.06%) while 2H ranges from -50.3 to -35.1%. The mean isotopic composition of precipitation collected at Alor Star meteorological station fall within the range of variation of the Kedah/Perlis groundwaters. In the southern part of the study site, the isotopic results indicate the occurence of two types of water; firstly the recharge is from the highlands where more negative 180 values and low tritium were observed and the second type is of local recharge where high tritium and less negative 180 values were observed. On the other hand, in the northern part of the basin the interpretation of stable isotopic results is quite difficult to be made at this stage. There was no correlation at all between tritium and 180 whatsoever. Results of the tritium assay show that some of the groundwater samples are pre-nuclear in age as indicated by low tritium content. Consequently, a Carbon-14 investigation was carried out from a few selected sites and their ages were found to be in the range of about 3000 to 5000 years. (author)

  17. Verification of strontium isotopes and its possible source in Indian basmati rice for geographical authentication study

    International Nuclear Information System (INIS)

    Due to globalization of food and agriculture product's market, there is increasing awareness of safety and authenticity of the food products. Consumers continuously demand the reassurance of origin and content of their foods. Hence safety and authenticity of food has been a growing analytical challenge. Basmati rice, the unique aromatic quality rice and a nature's gift to Indian sub-continent is produced and consumed on a large scale. Due to its profitable market as well as great demand overseas true Basmati rice market is facing unfair competition by unscrupulous producers for profit. Very few researches for geographical authentication are available for Indian basmati rice. Sr isotope composition of rice could be used as a geographical source indicator; however, little information is available on the possible source (lithogenic, biogenic, silicate, carbonate) of Sr in Rice or any other food stuff for tracing the geographical origin using Strontium isotopes as tracer. Hence in order to determine suitability of strontium isotopes as tracer and its possible source in rice for geographical authentication study, strontium isotope signature study of authentic Indian Basmati rice along with in situ soil and water of that region have been carried out

  18. Radiochemical neutron activation analysis of zinc for stable isotope tracer studies in human nutrition

    International Nuclear Information System (INIS)

    Stable isotopes are beginning to be used to study trace element nutrition in humans. As they do not expose subjects to radiation, they will be very useful for population groups that can not be studied with radioactive tracers (pregnant women and persons under the age of 18). The zinc stable isotope used in experiments was 70Zn whose abundance was increased from 0.62% to 66%. Blood, urine and feces samples were collected at various times after the administration of the tracer and the ratios of Zn-70/Zn-64 and Zn-70/Zn-68 were determined in the collected samples. Neutron Activation Analysis (NAA) was used to determine the Zn isotopes. As biological samples contain large quantites of Na, Cl, Br, K it was necessary to separate these in order to detect Zn isotopes. Pre and post-irradiation separations were done. Chelex-100 was used for former, Mn was precipitated as MnO2 and Cu was separated by dithizone extraction. The yields for pre and post-irradiation separations for 90 samples were 86+-16% and 70+-13% respectively. (author)

  19. Zinc homeostasis in man: studies using a new stable isotope-dilution technique

    International Nuclear Information System (INIS)

    A new method has been developed for the study of zinc metabolism in man using the stable isotope 67Zn. The technique involves intravenous infusion of the isotope followed by measurements of the plasma and faecal enrichments over a period of days. A procedure for the analysis of Zn isotopes in plasma and faeces is described which requires the separation of Zn from other elements using the chelator dithizone before analysis by thermal-ionization mass spectrometry. The stable isotope technique has been used in conjunction with a metabolic balance study to obtain measurements of Zn absorption and gastrointestinal secretion in a normal subject. Preliminary measurements of the size of the exchangeable pool of Zn have been made as have estimates of the rates of plasma and whole-body Zn turnover. Following an increase in dietary Zn the body appeared to respond in two ways. The gastrointestinal secretion of Zn increased immediately, but only by a relatively small amount. The absorption of Zn initially increased in proportion to the increase in dietary levels but then decreased within 4 d by an amount sufficient to restore Zn balance. (author)

  20. Neonatal Respiratory Diseases in the Newborn Infant: Novel Insights from Stable Isotope Tracer Studies.

    Science.gov (United States)

    Carnielli, Virgilio P; Giorgetti, Chiara; Simonato, Manuela; Vedovelli, Luca; Cogo, Paola

    2016-01-01

    Respiratory distress syndrome is a common problem in preterm infants and the etiology is multifactorial. Lung underdevelopment, lung hypoplasia, abnormal lung water metabolism, inflammation, and pulmonary surfactant deficiency or disfunction play a variable role in the pathogenesis of respiratory distress syndrome. High-quality exogenous surfactant replacement studies and studies on surfactant metabolism are available; however, the contribution of surfactant deficiency, alteration or dysfunction in selected neonatal lung conditions is not fully understood. In this article, we describe a series of studies made by applying stable isotope tracers to the study of surfactant metabolism and lung water. In a first set of studies, which we call 'endogenous studies', using stable isotope-labelled intravenous surfactant precursors, we showed the feasibility of measuring surfactant synthesis and kinetics in infants using several metabolic precursors including plasma glucose, plasma fatty acids and body water. In a second set of studies, named 'exogenous studies', using stable isotope-labelled phosphatidylcholine tracer given endotracheally, we could estimate surfactant disaturated phosphatidylcholine pool size and half-life. Very recent studies are focusing on lung water and on the endogenous biosynthesis of the surfactant-specific proteins. Information obtained from these studies in infants will help to better tailor exogenous surfactant treatment in neonatal lung diseases. PMID:27251153

  1. Isotope-aided studies of the bioavailability of iron from Myanmar diets

    International Nuclear Information System (INIS)

    Iron deficiency is an important nutritional problem in Myanmar. The preliminary studies in this paper are to be used as a feasibility study for an iron fortification programme in Myanmar. This programme is now in the planning stages. This paper contains summaries of information gathered from a dietary survey, isotope-aided studies of the bioavailability of iron from the daily diet, and a work plan for fortifying table salt with iron. 6 refs, 6 tabs

  2. Runoff components and mean residence times in water balance studies using environmental isotopes

    International Nuclear Information System (INIS)

    the subsurface reservoirs were derived from comparisons of the 3H and 2H or 18O input and output functions, the specific hydrological models and the model age distributions applied. Tr varies between 1.5 and 4 years in the studied areas, the results from stable-isotope and 3H data being in good agreement (Maloszewski, P., Rauert, W. Stichler, W., Herrmann, A., J. Hydrol. 66 (1983)). By introducing hydrological data, such as mean and minimum stream flow, it was possible to discriminate between two separate sub-reservoirs with different Tr values, i.e. 0.1-1 year and 4-7 years. The combination of hydrological and isotopical investigation methods enables a new insight into the water balances of the studied catchment areas. For example, the infiltration rates amount to about 50% of the precipitation depths, allowing for an evaporation loss of 25%. The subsurface storage volumes are of the order of 108 times the discharge, with Tr of 2.5 years. Assuming effective porosities of 20%, the calculated mean aquifer thickness is of the order of 10-15 times the precipitation depths. (author)

  3. Cryogenic distillation of CH4 for 12C/13C separation

    International Nuclear Information System (INIS)

    Tokyo Gas imports a large amount of LNG (Liquefied Natural Gas). LNG is - 163degC at atmospheric pressure and re-gasified by heat exchange with sea water for distribution. We have studied the effective utilization of this cold energy such as air separation and power generation. The cryogenic distillation is one of the next targets. A pilot plant of a reduced pressure and cryogenic fractional distillation process using methane for production of 13C at 50 % concentration has been built, and operated for two years. Two more distillation columns are now under starting-up operation. One is to enrich 13C more to 98 %. The other is to have 12C at 99.9 %. Liquid 13CH4 has a vapor pressure 0.3 % greater than that of 13CH4. Therefore fractional distillation would concentrate 12CH4, which is the heavier isotope in this system, in the liquid phase. The pilot plant, dealing with a mixture whose separation factor is close to unity, has to have a great height with many columns. And the process flows are very low compared with the boil-up in the columns. 9 columns for the methane-13 production can be divided into 3 groups in series. The other single column is for the methane-12 separation. These columns are packed with newly developed small wire packing. (author)

  4. Limnological controls on stable isotope records of late-holocene palaeoenvironment change in sw greenland: A paired lake study

    DEFF Research Database (Denmark)

    Olsen, Jesper; John Anderson, N.; Leng, M.J.

    2013-01-01

    Stable isotope records are increasingly being used in palaeoenvironmental studies of Arctic lakes. Here we compare stable isotope and elemental records (δ13C, δ15N, C/N) with high resolution XRF-derived geochemical and colour data from low Arctic lakes (SS1220 and SS85) in southwest Greenland. Lake...

  5. Complex isotope-hydrogeological studies of deep waters of the southern margin of the North German-Polish depression

    International Nuclear Information System (INIS)

    A well explored area within the North German-Polish depression, with a tectonically disturbed character in part, serves as an example to draw conclusions capable of being generalized on the genesis of Permian and Triassic deep waters be means of isotope-hydrogeological studies. The discussion includes 18O, D, 34S and carbon isotopes. (author)

  6. Hydrogeochemical and Isotopic Characteristics of Tufa Precipitating Wates: A Case Study of the River Krka (Slovenia)

    International Nuclear Information System (INIS)

    The geochemical and stable isotope composition of tufa precipitating water in the River Krka in the Slovenian karst area were studied. Surface water chemistry in the River Krka is controlled by groundwater interactions with carbonate rocks, soil CO2 and meteoric water in the aquifer. Major element chemistry of water is controlled by dissolution of dolomite and calcite. The aquifer is the main source of cations, since concentrations of Mg2+, Sr2+ and Ba2+ in water are highest at the spring. Ca2+ concentrations are slightly increasing due to the additional mixing of surface and groundwater downstream. Oxygen isotope composition of water indicates homogenization of meteoric water in the aquifer, while δ13C values of dissolved inorganic carbon in water are affected by biological activity in the soil. δ18O and δ13C of bulk tufa show that deposition of tufa precipitates in the River Krka is kinetically controlled resulting in enrichment with heavier isotopes. Calculated equilibrium temperature of tufa precipitation based on the oxygen isotope composition of water and tufa fit with measured water temperature when average δ18O values of water and tufa are considered. (author)

  7. Carbon allocation in plants and ecosystems - insights from stable isotope studies

    Science.gov (United States)

    Gessler, Arthur

    2014-05-01

    Trees are large global stores of carbon (C) that will be impacted by increased carbon dioxide levels and climate change. However, at present we cannot properly predict the carbon balance of forests in future as we lack knowledge on how plant physiological processes, the transfer of carbon within the plant, carbon storage, and remobilization in the plant tissues as well as the release of carbon from the roots to the soil interact with environmental drivers and ecosystem-scale processes. This paper will summarise how stable isotope techniques can give new insights in the fate of newly assimilated C in plants and ecosystems on time scales from hours to seasons and it will include studies either characterizing temporal and spatial variation in the natural abundance of carbon and oxygen isotopes or applying isotopically enriched tracers. It comprises the assessment of the mechanisms of C partitioning among specific metabolic pathways, between plant organs and into various ecosystem C pools with different residence times. Moreover stable isotopes are highly suitable tools to characterise the role of the phloem, which is the central long-distance conveyer distributing C from source to sinks and thus plays a central role in linking sites and structures of storage, growth and other metabolic activities. A deeper understanding of these processes and their interaction with environmental drivers is critical for predicting how trees and ecosystems will respond to coming global environmental changes, including increased temperature, altered precipitation, and elevated carbon dioxide concentrations.

  8. Study of μs isomers in neutron-rich indium and cadmium isotopes

    International Nuclear Information System (INIS)

    Microsecond isomers in In and Cd isotopes, in the mass range A=123 to 130, were investigated at the ILL reactor, Grenoble, through thermal-neutron induced fission reactions of Pu targets. The LOHENGRIN mass spectrometer has been used to select the recoiling fission fragments. The level schemes of the odd-even 123,125,127,129In and 125Cd, and new measurements of the microsecond half-lives of the odd-odd 126-130In are reported. However, the expected 8+ isomers in the even-even 126,128,130Cd isotopes were not observed. The comparisons between the experimental B(M2) strengths for In and Sn isotopes are discussed. A shell-model study of the heaviest In and Cd nuclei was performed using a realistic interaction derived from the CD-Bonn nucleon-nucleon potential. The calculation predicts values of the half-lives of the first 8+ states in 126,128Cd of about 10 ns, which could explain the non-observation of microsecond isomers. Comparison shows that the calculated levels of 130In and 129In are in good agreement with the experimental values, while some discrepancies occur for the lighter In isotopes. The collectivity of 126,128Cd is discussed in the framework of the shell model and in comparison with 204Hg. A theoretical prediction on 130Cd is reported

  9. Applications of compound-specific carbon isotope ratios in organic contaminant studies

    International Nuclear Information System (INIS)

    In this paper results are presented on the application of compound-specific isotope ratios measurements to assess biodegradation of chlorinated solvents, in particularly on microbial dechlorination of tetrachloroethene (PCE) and trichloroethene (TCE). Analytical aspects and isotope data from laboratory and field studies are discussed. The analytical tests showed that both headspace and SPME techniques provide accurate δ13C values with a similar precision for a wide range of chlorinated solvents. However, the SPME method is generally more sensitive. The microcosm experiments show that a significant isotopic fractionation occurs during dechlorination of PCE and TCE to ethene. The largest fractionation factors are observed in the steps DCE-VC and VC-Ethene. In general, the δ13C of each dechlorination product was always more negative than the δ13C of the corresponding precursor. In addition, the δ13C values of each compound increased with time. A similar pattern was observed for dechlorination of PCE at a field site. These results show that compound-specific carbon isotope ratios technology is a very sensitive tool for evaluation of natural attenuation of chlorinated solvents in groundwater. (author)

  10. Laser-mass spectrometric studies on measurement of isotopic ratios Sm and Nd

    International Nuclear Information System (INIS)

    Measurements of isotopic ratio is important in many areas of research such as nuclear technology, geochemistry etc. However, depending on the nature of application of such data, the required accuracy and precision will also vary. For instance, in geochemistry, with subnanogram foraminifera samples, one needs to measure the ratio to within a very small variation (± 50‰) compared to natural isotopic composition. Whereas, in the boron enrichment plant (20-90 atom %), the accuracy needed is about ± 1 atom %. In the former case, one needs to make measurements using an expensive instruments such as a magnetic sector mass spectrometer coupled with a suitable ionization method. For the latter application, one can use less expensive instruments such as, quadrupole mass filer (QMF) or time-of-flight mass spectrometer (TOF-MS) etc. In the present work the effect of pulse width of Nd-YAG laser on the measurement of isotopic ratio of Sm and Nd is studied using an in-house developed Laser Ionization Mass Spectrometer (LIMS) facility. The picosecond Cps) laser seems to provide better data compared to nanosecond (ns) laser. This LIMS method is a relatively simple method to measure the isotope ratios to within ± 1%. (author)

  11. A study of in-line plutonium isotopic analysis for gaseous plutonium hexafluoride

    International Nuclear Information System (INIS)

    In-line plutonium isotopic analysis of gaseous plutonium hexafluoride (PuF6) is very important for process control and special nuclear material accountability in any plutonium-isotope-separation process that requires a gaseous phase. Although much effort had been devoted to analyze arbitrary plutonium samples, no isotopic analysis had been done on gaseous PuF6 samples. We have initiated a study on the use of a high-resolution, gamma-ray spectroscopy technique to analyze gaseous plutonium hexafluoride. For the first time, PuF6 gas samples with pressures varying from 0.15 to 31 torr, which were directly fed into a gas cell from a process flow loop, were measured. The isotopic results of these measurements agree very well with those of mass spectrometry measurements of solid PuF4. The precision of a 10-min measurement of a 10-torr reactor-grade PuF6 is 1.5% for 238Pu, 0.22% for 239Pu, 0.87% for 240Pu, and 17.5% for 241Pu

  12. The use Pb- and Sr- isotopes for the study of Pacific Islander population

    International Nuclear Information System (INIS)

    Lead isotope measurements of dental enamel are regularly used as a means of determining information as to the source of the lead burden in modern human populations (Gulson and Wilson 1994). Lead ions have a considerable propensity to replace calcium ions in skeletal hard tissue; principally composed of hydroxy-apatite. The lead isotopic composition of teeth in adult humans has been shown to relate directly to the subject's exposure to the element at the time of eruption of their adult teeth and is unaffected by changes in the lead burden of an individual in latter life. In children, the analogous lead burden relates to the lead exposure of the mother during pregnancy and in the neo-natal period. Moreover due to its high crystallinity and density dental enamel does not undergo post-mortem recrystallization. This fact raised the exciting possibility that isotopic measurements of hard tissue could be used as a means of determining whether and individual is a migrant to a particular region. Despite a number of complications, briefly described, this paper presents the results of the ongoing study which uses measurements of Sr and Pb isotopes within dental enamel to determine the origin of Pacific Islander populations

  13. The use Pb- and Sr- isotopes for the study of Pacific Islander population

    Energy Technology Data Exchange (ETDEWEB)

    Budd, P.; Gulson, B.L.; Montgomery, J.; Rainbird, P.; Thomas, R.G.; Young, S. [New England Univ., Armidale, NSW (Australia)

    1997-12-31

    Lead isotope measurements of dental enamel are regularly used as a means of determining information as to the source of the lead burden in modern human populations (Gulson and Wilson 1994). Lead ions have a considerable propensity to replace calcium ions in skeletal hard tissue; principally composed of hydroxy-apatite. The lead isotopic composition of teeth in adult humans has been shown to relate directly to the subject`s exposure to the element at the time of eruption of their adult teeth and is unaffected by changes in the lead burden of an individual in latter life. In children, the analogous lead burden relates to the lead exposure of the mother during pregnancy and in the neo-natal period. Moreover due to its high crystallinity and density dental enamel does not undergo post-mortem recrystallization. This fact raised the exciting possibility that isotopic measurements of hard tissue could be used as a means of determining whether and individual is a migrant to a particular region. Despite a number of complications, briefly described, this paper presents the results of the ongoing study which uses measurements of Sr and Pb isotopes within dental enamel to determine the origin of Pacific Islander populations. Paper no. 72; Extended abstract. 4 refs.

  14. Isotopic variation in spring water and rain water of Sikkim: a case study

    International Nuclear Information System (INIS)

    Environmental stable isotopic signatures of surface water, rainwater and groundwater provide valuable information about interconnection between them. Stable isotopes of H (δ2H) and O (δ18O) have been widely employed by many researchers to understand rainwater, surface water and groundwater inter-connections. The Global Meteoric Water Line (GMWL, δD= 8 x δ18O+10) the locus of precipitation water over whole of the globe, established by Craig, used to tell about the environment of water. For the objective spring water (namely Dhalay Khola, Lower Changey and Bhulkey) were collected from the study area (Sikkim) during May 2013, March 2013 and August 2014. Rainwater sample were also collected with increasing altitude. These samples were analyzed for environmental isotopes (δ2H, δ18O) by a isotope ratio mass spectrometer (IsoPrime-100) using pyrolysis mode of elemental analyzer for deuterium and gas equilibration method for 18O. The precision (2 sigma) of (δ2H and δ18O are ±0.15 and ± 0.1‰ respectively

  15. Experimental study on storage of hydrogen isotopes on a titanium bed

    International Nuclear Information System (INIS)

    As known the Nuclear Power Plant Cernavoda, equipped with a Canadian reactor of CANDU type, is the most powerful tritium source from Europe. On long term, due to a 6 x 1016 Bq/year emission, Cernavoda area will be contaminated with an increasing tritium quantity. Also, the continuous contamination of heavy water from the reactor, induces a decline in the moderation's capacity. Hence one considers that it is improper the use of heavy water after 40 Ci/kg in the moderator and 2 Ci/kg in the cooling fluid. For these reasons, we have developed a detritiation technology, based on catalytic isotopic exchange and cryogenic distillation. Tritium will be removed from the tritiated heavy water, so it appears the necessity of storage of tritium in a special vessel that can provide a high level of protection and safety of environment and personal. There was tested several metals as storage beds for hydrogen isotopes. One of the reference materials used for storage of hydrogen isotopes is uranium, a material with a great storage capacity, but unfortunately it is a radioactive metal and also can react with the impurities from stored gas. Other metals and alloys as ZrCo, Ti, FeTi are also adequate as storage beds at normal temperature. The paper presents studies about the reaction between hydrogen and titanium used as storage bed for the hydrogen isotopes resulted after the detritiation of tritiated heavy water. The experiments that were made use hydrogen as process gas at different storage parameters. (authors)

  16. Study of Proton Magic Even-Even Isotopes and Giant Halos of Ca Isotopes with Relativistic Continuum Hartree-Bogoliubov Theory

    CERN Document Server

    Zhang, S Q; Toki, H; Tanihata, I; Zhou, S G

    2003-01-01

    We study the proton magic O, Ca, Ni, Zr, Sn, and Pb isotope chains from the proton drip line to the neutron drip line with the relativistic continuum Hartree-Bogoliubov (RCHB) theory. Particulary, we study in detail the properties of even-even Ca isotopes due to the appearance of giant halos in neutron rich Ca nuclei near the neutron drip line. The RCHB theory is able to reproduce the experimental binding energies $E_b$ and two neutron separation energies $S_{2n}$ very well. The predicted neutron drip line nuclei are $^{28}$O, $^{72}$Ca, $^{98}$Ni, $^{136}$Zr, $^{176}$Sn, and $^{266}$Pb, respectively. Halo and giant halo properties predicted in Ca isotopes with $A>60$ are investigated in detail from the analysis of two neutron separation energies, nucleon density distributions, single particle energy levels, the occupation probabilities of energy levels including continuum states. The spin-orbit splitting and the diffuseness of nuclear potential in these Ca isotopes are studied also. Furthermore, we study the...

  17. The carbon isotope study of biomarkers in the Maoming and the Jianghan tertiary oil shale

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In terms of the individual carbon isotope data of biomarkers present in the typical freshwater lake sediment (Maoming oil shale) and saline lake sediment lake (Jianghan oil shale) of China, this paper discusses their precursors and depositional environments of biomarkers in both sediment samples. Our studies showed that phytane and pristane of the Maoming oil shale were derived from the phytol side chain of chlorophyll a. By comparing the isotopic composition of 4-methyl sterane with that of sterane and hopane, it is suggested that 4-methyl sterane which has a higher abundance in the Maoming oil shale come from bacteria. The isotopic composition of biomarkers from the Jianghan rock sample (saline lake sediment ) is significantly different from that of the Maoming oil shale (freshwater lake sediment). Gammacerane was derived from haloprotozoan, with δ13C being about -25.8‰, just in consistency with the value reported in previous studies. The isotopic composition of phytane and pristane in the Jianghan rock is similar to that of sterane and 4-methyl sterane derived from phytoplanktons, illustrating their commonprecursors were algae. This paper reported for the first time the carbon isotope data of porphyrin obtained by GC-IRMS techniques. The approximate δ13C of C32DPEP and C31DPEP porphyrin from the Jianghan Basin indicated that the porphyrin was derived from chlorophyll. In the Maomingoil shale C32DPEP was enriched in 13C relative to C32etio and C31DPEP, implying that C32DPEP came from chlorophyll, and C32etio and C31DPEP are of other origins.

  18. Water uptake in woody riparian phreatophytes of the southwestern United States: a stable isotope study

    International Nuclear Information System (INIS)

    Alluvial forest associations are often dominated by woody phreatophytes, plants that are tightly linked to aquifers for water uptake. Anthropogenic hydrological alterations (e.g., water impoundment or diversion) are of clear importance to riparian ecosystem function. Because decreased frequency of flooding and depression of water tables may, in effect, sever riparian plants from their natural water sources, research was undertaken to determine water uptake patterns for the dominant native and introduced woody taxa of riparian plant communities of the southwestern United States. At floodplain study sites along the Bill Williams and lower Colorado Rivers (Arizona, USA), naturally occurring D and 18O were used to distinguish among potential water sources. Isotopic ratios from potential uptake locations were compared to water extracted from the dominant woody taxa of the study area (Populus fremontii, Salix gooddingii, and Tamarix ramosissima) to elucidate patterns of water absorption. Isotopic composition of water obtained from sapwood cores did not differ significantly from heartwood or branch water, suggesting that heartwood water exchange, stem capacitance, and phloem sap mixing may be inconsequential in actively transpiring Salix and Populus. There was evidence for close hydrologic linkage of river, ground, and soil water during the early part of the growing season. Surface soils exhibited D enrichment due to cumulative exposure to evaporation as the growing season progressed. Isotopic ratios of water extracted from Populus and Salix did not exhibit isotopic enrichment and were not significantly different from groundwater or saturated soil water sources, indicating a phreatophytic uptake pattern. Associations of isotopic ratios with water relations parameters indicated high levels of canopy evaporation and possible use of moisture from unsaturated alluvial soils in addition to groundwater in Tamarix. (author)

  19. Isotopic study of water exchange between atmosphere and biosphere at different sites in Pakistan

    International Nuclear Information System (INIS)

    Study of Isotopic behavior of water exchange between atmosphere and biosphere was initiated to understand the ties between these two spheres. This report presents the isotopic data of delta/sup 18/O and delta /sup 2/H in the water contents of leaves and stems in different plant species along with soil moisture. Non woody plants of wheat and grass along with soil from the surface and from the depth of 7 cm were collected during January 2005 to April 2005. Woody plants of many species were sampled from two sites near Islamabad and Lahore. Air moisture was also collected in the field. Moisture contents from these samples were extracted using the vacuum distillation method and analyzed for /sup 18/O and /sup 2/H Data depicts that the /sup 18/O and /sup 2/H of moisture in the leaves of non- woody and woody plants are much more enriched than their respective stems. This behavior is due to the evaporative enrichment trend originating from the soil moisture in the active root zone and also from the surface of the leaf. Degree of enrichment depends on the size of leaves, temperature, wind speed, stomatal resistance, soil chemistry and humidity. Significant evaporation effects in the moisture of grass stems are due to photosynthesis. Reflection of typical isotopic values of individual rain events is also observed in soil, plant water and atmospheric moisture, which can be used for studying water-use efficiency. Leaves of woody plants have relatively depleted/sup 18/O values during wet (monsoon) period mainly due to retardation of fractionation resulting from higher humidity. The stem samples do not show any significant variation in delta/sup 18/O indicating no evaporation from stems of big trees. Degree of enrichment of leave samples of woody plants also indicates the species- specific effects in oxygen and hydrogen isotopes during transpiration. Pine and Eucalyptus leaves show more variation in the isotopic contents as compared to other species. (author)

  20. Studies of osteoporosis in Croatia using isotope related techniques

    International Nuclear Information System (INIS)

    A short overview is presented of research activities concerning osteoporosis and trace element exposure monitoring carried out by the Institute for Medical Research and Occupational Health in Zagreb during the last forty years. The overview includes: cross-sectional and Prospective epidemiological studies in districts with habitually low and high calcium intake; clinical studies concerning peak bone mass and bone mineral density in Postmenopausal women; studies on trace element exposure monitoring. The collaborating institutions, agencies and relevant recent publications are quoted. A survey is given of relevant methods which were used in earlier studies as well as the techniques which will be used in the current IAEA project. A brief description of the work which will be undertaken (particularly during the first year) within the framework of the IAEA CRP is given. (author)

  1. Carbon-13 kinetic isotope effects in the decarbonylations of lactic acid containing 13C at the natural abundance level

    International Nuclear Information System (INIS)

    The 13C kinetic isotope fractionation in the decarbonylation of lactic acid of natural isotopic composition by sulfuric acid has been studied in the temperature range of 20-80 deg C. The 13C(1) isotope separation in the decarbonylation of lactic acid by concentrated sulfuric acid depends strongly on the temperature above 40 deg C. Below this temperature the 13C isotope effect in the decarbonylation of lactic acid by concentrated sulfuric acid is normal similarly as has been found in the decarbonylation of lactic [1-14C] acid. The experimental values of k(12C)/k(13C) ratios of isotopic rate constants for 12C and 13C are close to, but slightly higher than theoretical 13C-kinetic isotope effects calculated (neglecting tunneling) under the asumption that the C(1)-OH bond is broken in the rate-controlling step of the dehydration reaction. Dilution of concentrated sulfuric acid with water up to 1.4 molar (H2O)/(H2SO4) ratio caused the increase of the 13C isotope fractionation from 1.0273 found in concentrated sulfuric acid at 80.5 deg C to 1.0536±0.0008 (at 80.6 deg C). A discussion of the abnormally high temperature dependence of 14C and 13C isotope fractionation in this reaction and the discussion of the problem of relative 14C/13C kinetic isotope effects is given. (author) 18 refs.; 2 tabs

  2. Use of stable isotopes in developing countries: safe markers for nutrition regime study

    International Nuclear Information System (INIS)

    Possible use of stable radioisotopes in studies on nutrition and medicine problems that may be used in investigations of babies, children, pregnant women is shown. Attention is paid to behaviour of limited number of elements: hydrogen, carbon, nitrogen, oxygen. The IAEA plans implementation of a new coordinated research program on use of stable isotopes for studying nutrition problems and related diseases. The program emphasis will be placed on protein metabolism measurements and estimation of energy consumption in control population groups in developing countries

  3. You Are What You Eat: Mass spectrometry in paediatric kinetic studies using stable isotopes

    OpenAIRE

    Schierbeek, Henk

    2009-01-01

    textabstractAn overview will be presented about applications of stable isotopes in paediatric research. Mass spectrometry has proven to be an essential tool for unravelling kinetic studies in a large range of different research disciplines related to intestinal diseases, obesities, severe cerebral palsy, oxidative stress and foetal metabolism. Due to the diversity and complexity of the different metabolites involved in these studies, there is a high demand on sophisticated mass spectrometric ...

  4. Geochemical study of boron isotopes in the process of loess weathering

    Institute of Scientific and Technical Information of China (English)

    ZHAO; Zhiqi; (

    2003-01-01

    [1]Palmer, M. R., Swihart, G. H., Boron isotope geochemistry: An overview, in Rev. Mineral 33, Boron Mineralogy, Petrology and Geochemistry (eds. Grew, E. S., Anovitz, L. M.), Washington, D. C.: Mineral Soc. Am., 1996, 709-744.[2]Chaussidon, M., Albarède, F., Secular boron isotope variations in the continental crust: An ion microprobe study, Earth Planet Sci. Lett., 1992, 108: 229-241.[3]Spivack, A. J., Edmond, J. M., Boron isotope exchange between seawater and the oceanic crust, Geochim. Cosmochim. Acta, 1987, 51: 1033-1043.[4]Vengosh, A., Chivas, A. R., Mcculloch, M. T. et al., Boron isotope geochemistry of Australian salt lakes, Geochim. Cosmochim. Acta, 1991, 55: 2591-2606.[5]Xiao, Y. K., Sun, D. P., Wang, Y. H. et al., Boron isotopic compositions of brine, sediments and source water in Da Qaidam Lake, Qinghai, China, Geochim Cosmochim Acta, 1992,56: 1561-1568.[6]Mcmullen, C. C., Cragg, C. B., Thode, H. G., Absolute rations of 11B/10B in Searles Lake borax, Geochim. Cosmochim. Acta, 1961, 23: 147-150.[7]Palmer, M. R., Sturchio, N. C., The boron isotope systematics of the Yellowstone National Park (Wyoming) hydrothermal system: A reconnaissance, Geochim. Cosmochim. Acta, 1990, 54: 2811-2815.[8]Arndsson, S., Andrèsdèttir, A., Processes controlling the distribution of boron and chlorine in natural waters in Iceland, Geochim. Cosmochim. Acta, 1995, 59: 4125-4146.[9]Aggarwal, J. K., Palmer, M. R., Bullen, T. D. et al., The boron isotope systematics of Iceland geothermal waters: 1. Meteoric water charged systems, Geochim. Cosmochim. Acta, 2000, 64: 579-585.[10]Spivack, A. J., Palmer, M. R., Edmond, J. M., The sedimentary cycle of the boron isotopes, Geochim. Cosmochim. Acta, 1987, 51: 1939-1949.[11]Liu Yingjun, Cao Liming, Li Zhaolin et al., Element Geochemistry (in Chinese), Beijing: Science Press, 1984, 422-428.[12]Schwarcz, H. P., Agyei, E. K., Mcmullen, C. C., Boron isotopic fractionation during clay adsorption

  5. Studies of osteoporosis in Russia using isotope-related techniques

    International Nuclear Information System (INIS)

    The main aim of the present study was to estimate the age dependence of mineral density for the different body regions in healthy population of the Russian European area (Moscow and surroundings). Besides, bone mineral density (BMD) was to be analyzed by two ways: both in vivo and in vitro. In vivo studies were carried out using the method of DEXA (LUNAR DPX-L Densitometer) at the Central Institute of Traumatology and Orthopedics (Moscow) on volunteers randomly chosen. Autopsy material received from Forensic Department of Municipal Hospital (Obninsk) was used for in vitro NAA analysis. For August 31, 1996 bone mineral density was studied by DEXA on 94 healthy citizens of Moscow aged 15-55 (62 women and 32 men). Bone mineral density of femoral neck (right and left), spine (front view, L2-L4) and total body was measured in each studied person. All the examined people were also put questions by a doctor to fill in the appropriate questionnaire (an adapted version of WHO osteoporosis project questionnaire, case control study, July 15, 1993)

  6. Use of environmental isotopes to study the recharge mechanisms and arsenic pollution of Bangladesh groundwater

    International Nuclear Information System (INIS)

    aquifers with arsenic free water. But according to the study of BGS and DPHE, the large δ13C variations observed in Bangladesh groundwaters reflect derivation of the DIC from these multiple sources; such as soil zone CO2, oxidation of organic matter, potential oxidation of CH4, dissolution of minerals and in places mixing with seawater. It is concluded that depth itself is not the best criterion for considering a deep tube well to be arsenic-free now or in the future. The isotopic composition of the groundwater provides a robust criterion. As a consequence of challenging results from the previous study, BAEC has the on-going TC project entitled 'Isotope Techniques for Mitigating Arsenic Contamination in Groundwater (BGD/8/018)' approved by IAEA implemented in the year 2001-2002. The detailed field campaigns were accomplished during August (monsoon season) 2001 in the 8 nos. nested wells at the IDE site, Savar and during November (dry season) 2002 in the 16 nos. shallow and deep wells in Chandpur area. The water samples for environmental isotopic analyses of 2H, He-3H, 18O, 13C, 14C and 34S were taken

  7. Studies of Colossal Magnetoresistive Oxides with Radioactive Isotopes

    CERN Multimedia

    2002-01-01

    We propose to study Colossal Magnetoresistive (CMR) oxides with several nuclear techniques, which use radioactive elements at ISOLDE. Our aim is to provide local and element selective information on some of the doping mechanisms that rule electronic interactions and magneto- resistance, in a complementary way to the use of conventional characterisation techniques. Three main topics are proposed: \\\\ \\\\ a) Studies of local [charge and] structural modifications in antiferromagnetic LaMnO$_{3+\\delta}$ and La$_{1-x}$R$_{x}$MnO$_{3}$ with R=Ca and Cd, doped ferromagnetic systems with competing interactions: - research on the lattice site and electronic characterisation of the doping element. \\\\ \\\\ b) Studies of self doped La$_{x}$R$_{1-x}$MnO$_{3+\\delta}$ systems, with oxygen and cation non- stoichiometry: - learning the role of defects in the optimisation of magnetoresestive properties. \\\\ \\\\ c) Probing the disorder and quenched random field effects in the vicinity of the charge or orbital Ordered/Ferromagnetic p...

  8. hydrological study of the basin of Tunja using isotopics technical

    International Nuclear Information System (INIS)

    In the carried out study, it is analyzed the generalities in the first place on the city of Tunja, keeping in mind the aspects of Topography, Climate Population and the projection of this last one until the year 2020, and of equal it forms the demand of drinkable water for these same projections. Then it is the Superficial Hydrology of the area in study, keeping in mind the physiographic parameters of the basin, behavior pluviometrical graphic, flows and evapotranspiration, towards them to calculate this way the infiltration and power to end up determining the hydraulic balance of the area. In the concerning to Geology, this it was carried out on the base of the rising of stratigraphic columns made in having traveled by different roads and roads bordering to the study area; based on this columns it was carried out a geologic map with all the characteristics of the formations in the area

  9. Studies of osteoporosis in Russia using isotope-related techniques

    International Nuclear Information System (INIS)

    Here presented is the programme to study bone characteristics of healthy men and women aged 20-54 comprising the urban population of Moscow and nearby cities to define those of normal population. The study will also include patients with characteristics for early osteoporosis symptoms. The latter includes subjects who took part in the Chernobyl clean-up operation. DEXA (spine, femoral neck, whole body) and ultrasound (heel) will be used to examine those of the normal population group. To study osteoporosis patients the iliac crest biopsy samples will be taken for subsequent neutron activation analysis. Contents of major and trace elements in bone specimens (rib, iliac crest) and teeth (molar, premolar) will be estimated by neutron activation and X-ray fluorescent analysis in autopsy material of healthy accident victims depending on the age and sex. (author)

  10. Studies of osteoporosis in Singapore using isotopic related technique

    International Nuclear Information System (INIS)

    Osteoporosis is becoming increasingly common in Asia as the population ages. It has been projected that 50% of all hip fractures in the world will occur in Asia by the next century. Singapore is not exempted from this problem of global aging as figures show that there is a rising incidence of hip fractures in the country. So far, studies on bone density in Singapore have been reported only for the Chinese population. Apart from the bone density, it has been reported that femoral neck geometry, like the hip axis length, contributed independently to the risk of hip fracture. The hip axis length is defined as the length from the lateral bone edge below the greater trochanter through the femoral neck to the medial bone edge of the inner pelvic brim. A longer hip axis length was associated with an increased risk of hip fractures. Several studies have also shown some racial differences in hip axis length. The Study of Osteoporotic Fractures Research Group found that the mean hip axis length of Asian and black women were significantly shorter than that of white women. In a recent study, women of African origin were found to have smaller bone widths and a shorter hip axis length than Caucasians. The authors estimated that this racial difference could contribute to almost 25% decrease risk of hip fracture among blacks. Likewise, a shorter hip axis length in Japanese women compared to American women may explain the lower incidence of hip fractures among the Japanese population despite lower BMD values. The main objectives of this study were: a) To determine the age of peak bone density in each study group b) To quantify differences in bone density as functions of age and sex c) To determine any differences in bone density and hip axis length among Chinese, Malay and Indian population. This report presents the results of BMD measurement and the data analysis performed

  11. Comparative international studies of osteoporosis using isotope techniques

    International Nuclear Information System (INIS)

    Over three hundred volunteers were recruited through newspaper advertisements and other means to measure the BMD of the lumbar spine and femoral neck of normal healthy Canadians from the Toronto area. Trained scientists or medical personnel with respect to their medical history, lifestyle and habits carefully interviewed all these people. Persons with histories that will affect bone mineral status were excluded from the study. The resulting study population consisted of 200 persons. The data was used to determine the age or the range of ages at which peak BMD is attained in this normal population. The measurements were made using a DEX4 instrument made by Hologic Inc., Model 1000W. (author)

  12. Study of thermochemical sulfate reduction mechanism using compound specific sulfur isotope analysis

    Science.gov (United States)

    Meshoulam, Alexander; Ellis, Geoffrey S.; Said Ahmad, Ward; Deev, Andrei; Sessions, Alex L.; Tang, Yongchun; Adkins, Jess F.; Liu, Jinzhong; Gilhooly, William P.; Aizenshtat, Zeev; Amrani, Alon

    2016-09-01

    The sulfur isotopic fractionation associated with the formation of organic sulfur compounds (OSCs) during thermochemical sulfate reduction (TSR) was studied using gold-tube pyrolysis experiments to simulate TSR. The reactants used included n-hexadecane (n-C16) as a model organic compound with sulfate, sulfite, or elemental sulfur as the sulfur source. At the end of each experiment, the S-isotopic composition and concentration of remaining sulfate, H2S, benzothiophene, dibenzothiophene, and 2-phenylthiophene (PT) were measured. The observed S-isotopic fractionations between sulfate and BT, DBT, and H2S in experimental simulations of TSR correlate well with a multi-stage model of the overall TSR process. Large kinetic isotope fractionations occur during the first, uncatalyzed stage of TSR, 12.4‰ for H2S and as much as 22.2‰ for BT. The fractionations decrease as the H2S concentration increases and the reaction enters the second, catalyzed stage. Once all of the oxidizable hydrocarbons have been consumed, sulfate reduction ceases and equilibrium partitioning then dictates the fractionation between H2S and sulfate (∼17‰). Experiments involving sparingly soluble CaSO4 show that during the second catalytic phase of TSR the rate of sulfate reduction exceeds that of sulfate dissolution. In this case, there is no apparent isotopic fractionation between source sulfate and generated H2S, as all of the available sulfate is effectively reduced at all reaction times. When CaSO4 is replaced with fully soluble Na2SO4, sulfate dissolution is no longer rate limiting and significant S-isotopic fractionation is observed. This supports the notion that CaSO4 dissolution can lead to the apparent lack of fractionation between H2S and sulfate produced by TSR in nature. The S-isotopic composition of individual OSCs record information related to geochemical reactions that cannot be discerned from the δ34S values obtained from bulk phases such as H2S, oil, and sulfate minerals, and

  13. Stable isotopes and Digital Elevation Models to study nutrient inputs in high-Arctic lakes

    Science.gov (United States)

    Calizza, Edoardo; Rossi, David; Costantini, Maria Letizia; Careddu, Giulio; Rossi, Loreto

    2016-04-01

    Ice cover, run-off from the watershed, aquatic and terrestrial primary productivity, guano deposition from birds are key factors controlling nutrient and organic matter inputs in high-Arctic lakes. All these factors are expected to be significantly affected by climate change. Quantifying these controls is a key baseline step to understand what combination of factors subtends the biological productivity in Arctic lakes and will drive their ecological response to environmental change. Basing on Digital Elevation Models, drainage maps, and C and N elemental content and stable isotope analysis in sediments, aquatic vegetation and a dominant macroinvertebrate species (Lepidurus arcticus Pallas 1973) belonging to Tvillingvatnet, Storvatnet and Kolhamna, three lakes located in North Spitsbergen (Svalbard), we propose an integrated approach for the analysis of (i) nutrient and organic matter inputs in lakes; (ii) the role of catchment hydro-geomorphology in determining inter-lake differences in the isotopic composition of sediments; (iii) effects of diverse nutrient inputs on the isotopic niche of Lepidurus arcticus. Given its high run-off and large catchment, organic deposits in Tvillingvatnet where dominated by terrestrial inputs, whereas inputs were mainly of aquatic origin in Storvatnet, a lowland lake with low potential run-off. In Kolhamna, organic deposits seem to be dominated by inputs from birds, which actually colonise the area. Isotopic signatures were similar between samples within each lake, representing precise tracers for studies on the effect of climate change on biogeochemical cycles in lakes. The isotopic niche of L. aricticus reflected differences in sediments between lakes, suggesting a bottom-up effect of hydro-geomorphology characterizing each lake on nutrients assimilated by this species. The presented approach proven to be an effective research pathway for the identification of factors subtending to nutrient and organic matter inputs and transfer

  14. Studies on osteoporosis in Chile using isotope-related techniques

    International Nuclear Information System (INIS)

    The relationship found between BMD of the lumbar spine with the anthropomorphic parameters (age, sex, body size and bone area) in the normal Chilean population studied, was different from the relationship found between BMD of both hips with the same parameters. To determine peak bone mass it is necessary to increase the number of individuals studied. This is specially true for BMD of the lumbar spine. It seems important for the correct interpretation of BMD studies to determine local values for normals, specially for the analysis of BMD in the lumbar spine, which is related to body and bone size. It is necessary to normalize the data base for anthropomorphic parameters specially in epidemiological studies. Knowledge of these parameters for the normal data base used in the different densitometers is highly desirable. There are some differences between this data base and that provided by Hologic, specially for spine in both sexes. This difference could be explained by size related factors. There is a correlation between osteocalcin levels and BMD in lumbar spine and both femoral necks only in women

  15. Radiation and isotopic techniques in the study and control of piroplasms of cattle: a review

    International Nuclear Information System (INIS)

    Radiation and isotopic techniques have been used in a number of ways to study Babesia and Theileria parasites (piroplasms), and in attempts to vaccinate animals against diseases induced by these agents. Work involving the piroplasm infections of cattle is reviewed in this paper. Some success has been achieved by using radiation to modify tick or bovine stages of parasites, for use as potential vaccines. Radiation has also been used to induce immuno-suppression in laboratory animals, in an effort to render them susceptible to bovine piroplasms, particularly Theileria. Isotope tracer techniques have been used for labelling parasites, and for studying metabolic pathways. Encouraging results, particularly with regard to vaccine development, indicate the importance of radiation techniques in the study and control of piroplasms of cattle. (Auth.)

  16. Studies of osteoporosis in Singapore using isotope related technique

    International Nuclear Information System (INIS)

    The main objectives of this study will be to determine the bone density in selected populations for the purposes of i)determining the age of peak bone mass in each study group and ii)quantifying the differences in bone density as functions of the age and sex of persons in the study group as well as quantifying the differences between study groups in different countries. Normal healthy subjects of both sexes across the age range of 15-50 will be recruited for this programme. There will be at least 15 subjects in each 5 year age range (i.e. a total of 105 subjects of each sex). The subjects will be of urban residency. The project will take a maximum of five years. Volunteers will be recruited from the hospital personnel and their friends and relatives. The subjects will be healthy individuals with no history of fractures and they should not be on any medication which may affect the bone density. A questionnaire regarding their lifestyle factors such as exercise, coffee/tea/alcohol intake and medication be filled. The subjects will also have X-rays of the dorsolumbar spine taken to ascertain the absence of scoliosis or crush fractures. Bone mineral density will be measured by dual energy X-ray absorptiometry using a Norland XR-26 bone densitometer. The BMD in the L2-L4 region of the lumbar spine and right hip which includes the femoral neck, trochanter and Ward's triangle will be scanned. Body composition will also be determined by doing a whole body scan on the subjects. Autopsy samples of rib bones from healthy accident victims in the age range 20-50 years will be obtained and the biomechanical strength of these bones will be tested. Biopsy specimens of the iliac crest will also be obtained to study the differences in trace element composition between osteoporotic patients and controls. (author)

  17. An isotopic study of fiber-water interactions

    Science.gov (United States)

    Walsh, Frances Luella

    A new technique for measuring the water content of fiber is presented. Tritiated water is added to a pulp/water suspension whereupon the tritium partitions between the bulk water and the pulp. Through this technique a fiber:water partition coefficient is developed, Kpw. This thesis will cover the development of the Kpw procedure and three different case studies. The first study involves comparing Kpw to traditional methods of fiber water content. The procedure provides a value of ten percent for the tightly bound water content of unrefined hardwood or softwood kraft fiber, either bleached or unbleached. If this water is assumed to cover the fiber surface as a monolayer, then an estimate of the wet surface area of fiber can be obtained. This estimate compares well to independent measurements of surface area. Kpw has also been found to be valuable in furthering the understanding of refining. Based on the study, it is proposed that refining occurs in three discrete stages. First, refining removes the primary cell wall and S1 layer while beginning to swell the S2 layer. Next, internal delamination occurs within the S2 layer. Finally, fiber destruction occurs at high refining levels. By using Kpw, the three stages of refining are clearly recognized. Lastly, Kpw is used to study the effect of hornification on bleached softwood kraft fiber. The recycling effects at three refining levels were characterized by Kpw and followed closely the findings of the refining study. At low and high refining levels, the impact of recycling was minimal according to Kpw results, but at 400 mL csf the impact of recycling was much more pronounced. This could be attributed to the closing of internal delaminations within the fiber.

  18. Studies on stable isotopic composition of daily rainfall from Kozhikode, Kerala, India.

    Science.gov (United States)

    Unnikrishnan Warrier, C; Praveen Babu, M; Sudheesh, M; Deshpande, Rajendrakumar D

    2016-06-01

    The stable isotopic compositions of all major daily rain fall samples (n = 113) collected from Kozhikode station in Kerala, India, for the year 2010 representing the pre-monsoon, southwest and northeast monsoon seasons are examined. The isotopic variations δ(18)O, δ(2)H and d-excess in daily rainfall ranged from δ(18)O: -4.4 to 2 ‰, δ(2)H: -25.3 to 13.8 ‰, and d-excess: -2.4 to 15.3 ‰; δ(18)O: -9.7 to -0.6 ‰, δ(2)H: -61.7 to 5.3 ‰, and d-excess 5.8 to 17.4 ‰; δ(18)O -11.3 to -1.4 ‰, δ(2)H: -75.3 to 0.9 ‰, and d-excess: 8.8 to 21.3 ‰ during the pre-, southwest and northeast monsoon periods, respectively. Thus, daily rainfall events during two monsoon periods had a distinct range of isotopic variations. The daily rain events within the two monsoon seasons also exhibited periodic variations. The isotopic composition of rain events during pre-monsoon and a few low-intensity events during the southwest monsoon period had imprints of secondary evaporation. This study analysing the stable isotopic characteristics of individual rain events in southern India, which is influenced by dual monsoon rainfall, will aid in a better understanding of its mechanism. PMID:26617222

  19. Hydrogeological and isotopic study of surface water and groundwater in the Eastern Haouz Plain. Western Morocco

    Science.gov (United States)

    El Mandour, Abdennabi; Rochdane, Samia; Reddy, Venkat; Himi, Mahjoub; Casas, Albert

    2014-05-01

    The Eastern Haouz area, characterized by a semi-arid climate, is part of the Haouz plain. The basin is built over a broad synclinal between the High Atlas and the Jebilets mountains. The compilation of geological, geophysical and hydrogeological data shows that this area is straddling two major basins of western Morocco. Map of the river system and the piezometric map show the same division line of surface water and groundwater. This division line oriented NNW-SSE is evidenced by the rise of the basement constituted by Paleozoic schists that outcrop near Tamelalt. Thus we can distinguish two main directions of groundwater flow feeding two watersheds (Tensift and Oum Rabiaa rivers) and two large reservoirs in the region of Marrakech. As a contribution to solve the water supply problem in the area, a hydrochemical study has been conducted, involving 40 groundwater samples for major ions and 20 stable isotope analyses. Hydrochemical results show the geological control on water quality. Samples from Paleozoic schists and Triassic sediments are relatively highly mineralisation and unsuitable for drinking as well as for irrigation. Conversely, groundwater from the alluvial plains is relatively less mineralised than other older geological formations; however, many of the samples are also non-potable. Apart of salinity problem, about 25% of the samples have higher nitrate content than the drinking water permissible limit. Stable isotope analysis show that groundwater recharge to the phreatic aquifer is controlled by local conditions. The small difference in the isotopic content of river water and a group of groundwater samples is interpreted as the evaporation effect during the recharge. On the other hand, the group of samples with relatively depleted stable isotopic content shows faster recharge conditions and less water-rock interaction. Finally, another group of samples is relatively enriched in stable isotope content and confirm an increase during the recharge

  20. A study of interaction between surface water and groundwater using environmental isotope in Huaisha River basin

    Institute of Scientific and Technical Information of China (English)

    SONG; Xianfang; LIU; Xiangchao; XIA; Jun; YU; Jingjie; TANG; Changyuan

    2006-01-01

    The surface water and groundwater are important components of water cycle,and the interaction between surface water and groundwater is the important part in water cycle research.As the effective tracers in water cycle research,environmental isotope and hydrochemistry can reveal the interrelationships between surface water and groundwater effectively.The study area is the Huaisha River basin,which is located in Huairou district,Beijing.The field surveying and sampling for spring,river and well water were finished in 2002 and 2003.The hydrogen and oxygen isotopes and water quality were measured at the laboratory.The spatial characteristics in isotope and evolution of water quality along river lines at the different area were analyzed.The altitude effect of oxygen isotope in springs was revealed,and then using this equation,theory foundation for deducing recharge source of spring was estimated.By applying the mass balance method,the annual mean groundwater recharge rate at the catchment was estimated.Based on the groundwater recharge analysis,combining the hydrogeological condition analysis,and comparing the rainfall-runoff coefficients from the 1960s to 1990s in the Huaisha River basin and those in the Chaobai River basin,part of the runoff in the Huaisha River basin is recharged outside of this basin,in other words,this basin is an un-enclosed basin.On the basis of synthetically analyses,combining the compositions of hydrogen and oxygen isotopes and hydrochemistry,geomorphology,geology,and watershed systems characteristics,the relative contributions between surface water and groundwater flow at the different areas at the catchments were evaluated,and the interaction between surface water and groundwater was revealed lastly.

  1. Studies on osteoporosis in Chile using isotope-related techniques

    International Nuclear Information System (INIS)

    Several studies on bone densitometry measurements in healthy individuals have been performed in Chile. However due to the fact that different techniques and no uniform protocols have been used to select patients, the results obtained are not suitable as reference values for a normal chilean population. Therefore, foreign reference values are used. This study will select healthy normal individuals, typical urban chilean residents, and measure bone density using the DEXA technique. The selection will be made according to a well defined protocol. Serum osteocalcin, a marker of bone remodeling, will be measured in all subjects as a means-a assessing bone metabolism. Bone trace element composition will be measured in selected subjects. Samples will be obtained by biopsy or through normal surgical procedures and will be analyzed by neutron activation analysis. (author)

  2. Theoretical Study on Properties of New Isotope 265Bh

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The properties of nuclei belonging to the newly observed α-decay chain starting from 265Bh have been studied. The axially deformed relativistic mean-field calculation with the force NL-Z2 has been performed in the blockedBCS approximation. Some ground state properties such as binding energies, deformations, spins, and parities, as well as Q-values of the α-decay for this decay chain have been calculated and compared with known experimental data. Good agreement is found. The single-particle spectrum of the nucleus 265 Bh is studied and some new magic numbers are found,while the magnitudes of the shell gaps in superheavy nuclei are much smaller than those of nuclei before the actinium region, and the Fermi surfaces are close to the continuum. Thus the superheavy nuclei are usually not stable. The The methods which give good agreement with the data are selected.

  3. Studies on osteoporosis in Chile using isotope-related techniques

    International Nuclear Information System (INIS)

    According to the objectives stated in the last coordination meeting, Bone mass density (BMD) measurements in men and women belonging to a healthy Chilean population, were continued. The selection of individuals was made in the manner described in previous reports, using the same exclusion criteria and using the modified WHO questionnaire. We present in this report the results of BMD measurements performed from the beginning of this study until May 1998. A statistical analysis of the data is presented

  4. Studies of osteoporosis in Shanghai, China, using isotope related techniques

    International Nuclear Information System (INIS)

    Using Hologic QDR-2000 DEXA, the BMD determinations of subjects suffering from osteoporosis and normal persons are in progress in Shanghai, China. A primary correlation between the kidney disease and the osteoporosis has been obtained. The studies of multi elemental distribution in cancellous bone of femoral head are also performed by PIXE. According to IAEA Co-ordinated Research Programme (CRP), a further working arrangement has been planned. (author)

  5. Status of reaction theory for studying rare isotopes

    OpenAIRE

    Nunes, F. M.; Upadhyay, N. J.

    2012-01-01

    Reactions are an important tool to study nuclear structure and for extracting reactions relevant for astrophysics. In this paper we focus on deuteron induced reactions which can provide information on neutron shell evolution as well as neutron capture cross sections. We review recent work on the systematic comparison of the continuum discretized coupled channel method, the adiabatic wave approximation and the Faddeev momentum-space approach. We also explore other aspects of the reaction mecha...

  6. Comparative international studies of osteoporosis using isotope techniques

    International Nuclear Information System (INIS)

    In Europe, there are great geographic variations in rates of osteoporotic fracture. The MEDOS study, a case-control study of hip fracture in southern Europe, demonstrated rates that in some age groups varied geographically by more than an order of magnitude. Additionally the prevalences of vertebral deforinities vary over a 3-fold range in both sexes. The incidence of hip fracture has also been shown to vary between another populations with apparently lower rates in Hong Kong and South Africa in Europe and North America. The greatest projected increases in hip fracture incidence will occur in China and South East Asia. It seems likely that the spread of fracture risk can at least be accounted for partly by differences in bone density. Bone density in later life is dependent on the maximum bone mass ('peak' bone mass) attained in early adulthood and the subsequent rate of loss. The purpose of this study was to determine whether early adult BMD varied between populations and to explore environmental and nutritional contributions to any detennined differences. The data analysed to-date demonstrate a highly significant difference in young adult bone mass across the centers. These differences are only partly attributable to differences in height and weight. By and large, low femoral neck BMD is accompanied by low spinal BMD. Femoral neck BMD appears constant between the age of 25-45 years, but this will require confirmation by further statistical analysis. The impact of family history, environmental factors and nutrition will be explored in subsequent analyses

  7. The suitability of the dual isotope approach (δ13C and δ18O) in tree ring studies

    Science.gov (United States)

    Siegwolf, Rolf; Saurer, Matthias

    2016-04-01

    The use of stable isotopes, complementary to tree ring width data in tree ring research has proven to be a powerful tool in studying the impact of environmental parameters on tree physiology and growth. These three proxies are thus instrumental for climate reconstruction and improve the understanding of underlying causes of growth changes. In various cases, however, their use suggests non-plausible interpretations. Often the use of one isotope alone does not allow the detection of such "erroneous isotope responses". A careful analysis of these deviating results shows that either the validity of the carbon isotope discrimination concept is no longer true (Farquhar et al. 1982) or the assumptions for the leaf water enrichment model (Cernusak et al., 2003) are violated and thus both fractionation models are not applicable. In this presentation we discuss such cases when the known fractionation concepts fail and do not allow a correct interpretation of the isotope data. With the help of the dual isotope approach (Scheidegger et al.; 2000) it is demonstrated, how to detect and uncover the causes for such anomalous isotope data. The fractionation concepts and their combinations before the background of CO2 and H2O gas exchange are briefly explained and the specific use of the dual isotope approach for tree ring data analyses and interpretations are demonstrated. References: Cernusak, L. A., Arthur, D. J., Pate, J. S. and Farquhar, G. D.: Water relations link carbon and oxygen isotope discrimination to phloem sap sugar concentration in Eucalyptus globules, Plant Physiol., 131, 1544-1554, 2003. Farquhar, G. D., O'Leary, M. H. and Berry, J. A.: On the relationship between carbon isotope discrimination and the intercellular carbon dioxide concentration in leaves, Aust. J. Plant Physiol., 9, 121-137, 1982. Scheidegger, Y., Saurer, M., Bahn, M. and Siegwolf, R.: Linking stable oxygen and carbon isotopes with stomatal conductance and photosynthetic capacity: A conceptual model

  8. Studies of osteoporosis in Croatia using isotope related techniques

    International Nuclear Information System (INIS)

    Research activities concerning the IAEA Osteoporosis Study in Croatia, during the period November 1995 - September 1996, are presented, as well as a brief summary of the study, revealing the effect of combined therapy with antiresorptive and bone stimulating agents on bone mineral density in postmenopausal women with osteopenia and osteoporosis. Bone mineral density was measured by the method of dual energy X-ray absorptiometry (Lunar DPX) in the lumbar spine (L2-L4) and at the left proximal femur (neck, Ward, trochanter) in a representative sample of 112 subjects of both sexes in the age range 15-50 years, from the city of Zagreb. Analysis of the scans and statistical evaluation of data are in progress. In a pilot study conducted in a sample of 67 college girls, ages 16-18, calcium intake, type and frequency of physical activity, alcohol consumption and smoking habit were roughly evaluated by use of a questionnaire. Height (cm), weight (kg) and calcium intake (mg/day) were (mean -+ SD) 169.4-+ 5.7, 57.8-+ 6.1, 937-+ 327, respectively. About 20 percent of girls drank less than 10 dL of wine or beer and less than 2 dL of spirits weekly, while 8% of them consumed 15-20 dL of wine or beer and 3-6 dL of spirits weekly. Fifteen percent smoked up to 20 cigarettes weekly and 5 percent 30-60 cigarettes weekly. Approximately 50 percent were regularly involved, in some kind of sporting activity, 2-3 times a week. Steps have been undertaken to organize evaluation of the present - day dietary habits of children from Istria, a part of Croatia, which was previously known as a low calcium region. All procedures necessary to start the work on a supplementary programme have been carried out. The plan for future work within the framework of the IAEA-CRP Osteoporosis Study is presented. The effect on bone mineral density of intermittent cyclical treatment with etidronate (group A) alone (400 mg orally for two weeks, followed by 500 mg of calcium daily for the next 10 weeks) and a

  9. Studies of osteoporosis in Croatia using isotope related techniques

    International Nuclear Information System (INIS)

    The study about bone stiffness in children and adolescents is finished. The relationship between habitual calcium intake, anthropometric measurements and bone stiffness was determined. In order to establish a national reference database, bone mineral density (BMD, g/cm2) of the lumbar spine (L2-L4) and of the left femoral neck of randomly chosen subjects, aged 20-49 years, was measured by dual x-ray absorptiometry (Lunar DPX). This report presents the results of BMD measurement and the data analysis performed

  10. Studies of osteoporosis in Singapore using isotope-related techniques

    International Nuclear Information System (INIS)

    The main objectives of this study was to determine the bone density for the purposes of i) determining the age of peak bone mass in each study group and ii) quantifying the differences in bone density as functions of age and sex. The results of estimating the age dependence of mineral density for the femoral neck, spine and total body of healthy women and men using DEXA are given. The age changes in concentrations of major minerals and electrolytes found for compact and trabecular bones of healthy male femoral neck with regard for the wet and dry tissue calculations are represented. Information about femoral neck water content depending on the age of healthy men is tabulated. The number of performed observations and analyses is evidently insufficient to make any final decision, however some preliminary conclusions can be drawn. In accordance with DEXA results, BMD maximum for the femoral neck, spine and total body of healthy women is found for 31-35 age period while that of healthy men is reached by 21-25 age period, i.e. 10 year earlier. Follow INAA results, the full-value mineralization for both compact and trabecular tissue of healthy male femoral neck takes place by 15-20 age period

  11. Isotope studies of nitrogen transformations in Castle Lake, California

    International Nuclear Information System (INIS)

    The use of the 14C and 15N tracer techniques in the past two decades has greatly increased the understanding of the role of inorganic nitrogen with regard to aquatic primary productivity. Both of these techniques have been used at Castle Lake, California, and the studies have been extended to include the 13N radiotracer method. Nitrogen-13-labelled nitrate was used to measure the short-term uptake rates of phytoplankton and they compare well with longer term 15N data. The 13N technique can also provide a sensitive assay for denitrification in natural systems without significant nitrate amendment. These nitrogen uptake studies show that the rate of ammonium uptake far exceeds that of nitrate. Ammonium enhances 14C fixation in the light and in the dark, suggesting algal populations are at certain times, under natural conditions, deficient in nitrogen. Simple analyses of external nitrogen loading rates are often inadequate for predicting levels of aquatic productivity since the two forms of dissolved inorganic nitrogen internally cycle at rather different rates, and denitrification can account for a significant loss of combined nitrogen. (author)

  12. Theoretical Study on Properties of New Isotope 265Bh

    International Nuclear Information System (INIS)

    The properties of nuclei belonging to the newly observed α-decay chain starting from 265Bh have been studied. The axially deformed relativistic mean-field calculation with the force NL-Z2 has been performed in the blocked BCS approximation. Some ground state properties such as binding energies, deformations, spins, and parities, as well as Q-values of the α-decay for this decay chain have been calculated and compared with known experimental data. Good agreement is found. The single-particle spectrum of the nucleus 265Bh is studied and some new magic numbers are found, while the magnitudes of the shell gaps in superheavy nuclei are much smaller than those of nuclei before the actinium region, and the Fermi surfaces are close to the continuum. Thus the superheavy nuclei are usually not stable. The α-decay lifetimes in the 265Bh decay chain are evaluated by different formulae, and compared with experimental data. The methods which give good agreement with the data are selected.

  13. A preliminary study of iron isotope fractionation in marine invertebrates (chitons, Mollusca) in near-shore environments

    Science.gov (United States)

    Emmanuel, S.; Schuessler, J. A.; Vinther, J.; Matthews, A.; von Blanckenburg, F.

    2014-10-01

    Chitons (Mollusca) are marine invertebrates that produce radulae (teeth or rasping tongues) containing high concentrations of biomineralized magnetite and other iron-bearing minerals. As Fe isotope signatures are influenced by redox processes and biological fractionation, Fe isotopes in chiton radulae might be expected to provide an effective tracer of ambient oceanic conditions and biogeochemical cycling. Here, in a pilot study to measure Fe isotopes in marine invertebrates, we examine Fe isotopes in modern marine chiton radulae collected from different locations in the Atlantic and Pacific oceans to assess the range of isotopic values, and to test whether or not the isotopic signatures reflect seawater values. Values of δ56Fe (relative to IRMM-014) in chiton teeth range from -1.90 to 0.00 ‰ (±0.05‰ (2σ) uncertainty in δ56Fe), probably reflecting a combination of geographical control and biological fractionation processes. Comparison with published local surface seawater Fe isotope data shows a consistent negative offset of chiton teeth Fe isotope compositions relative to seawater. Strikingly, two different species from the same locality in the North Pacific (Puget Sound, Washington, USA) have distinct isotopic signatures. Tonicella lineata, which feeds on red algae in the sublittoral zone, has a mean δ56Fe of -0.65 ± 0.26‰ (2σ, 3 specimens), while Mopalia muscosa, which feeds on both green and red algae in the eulittoral zone, shows lighter isotopic values with a mean δ56Fe of -1.47 ± 0.98‰ (2σ, 5 specimens). Three possible pathways are proposed to account for the different isotopic signatures: (i) physiologically controlled processes within the chitons that lead to species-dependent fractionation; (ii) diet-controlled variability due to different Fe isotope fractionation in the red and green algal food sources; and (iii) environmentally controlled fractionation that causes variation in the isotopic signatures of bioavailable Fe in the different

  14. Decay studies of the highly neutron-deficient indium isotopes

    International Nuclear Information System (INIS)

    An extension of the experimentally known nuclidic mass surface to nuclei far from the region of beta-stability is of fundamental interest in providing a better determination of the input parameters for the various nuclear mass formulae, allowing a more accurate prediction of the ultimate limits of nuclear stability. In addition, a study of the shape of the mass surface in the vicinity of the doubly-closed nuclide 100Sn provides initial information on the behavior of the shell closure to be expected when Z = N = 50. Experiments measuring the decay energies of 103105In by β-endpoint measurements are described with special attention focused on the development of a plastic scintillator β-telescope coupled to the on-line mass separator RAMA (Recoil Atom Mass Analyzer). An attempt to measure the β-endpoint energy of 102In is also briefly described. The experimentally determined decay energies and derived masses for 103105In are compared with the predictions of different mass models to identify which models are more successful in this region. Furthermore, the inclusion in these comparisons of the available data on the neutron-rich indium nuclei permits a systematic study of their ground state mass behavior as a function of the neutron number between the shell closures at N = 50 and N = 82. These analyses indicate that the binding energy of 103In is 1 MeV larger than predicted by the majority of the mass models. An examination of the Q/sub EC/ surface and the single- and two-neutron separation energies in the vicinity of 103105In is also performed to investigate further the deviation and other possible systematic variations in the mass surface in a model-independent way

  15. Decay studies of the highly neutron-deficient indium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Wouters, J.M.

    1982-02-01

    An extension of the experimentally known nuclidic mass surface to nuclei far from the region of beta-stability is of fundamental interest in providing a better determination of the input parameters for the various nuclear mass formulae, allowing a more accurate prediction of the ultimate limits of nuclear stability. In addition, a study of the shape of the mass surface in the vicinity of the doubly-closed nuclide /sup 100/Sn provides initial information on the behavior of the shell closure to be expected when Z = N = 50. Experiments measuring the decay energies of /sup 103/ /sup 105/In by ..beta..-endpoint measurements are described with special attention focused on the development of a plastic scintillator ..beta..-telescope coupled to the on-line mass separator RAMA (Recoil Atom Mass Analyzer). An attempt to measure the ..beta..-endpoint energy of /sup 102/In is also briefly described. The experimentally determined decay energies and derived masses for /sup 103/ /sup 105/In are compared with the predictions of different mass models to identify which models are more successful in this region. Furthermore, the inclusion in these comparisons of the available data on the neutron-rich indium nuclei permits a systematic study of their ground state mass behavior as a function of the neutron number between the shell closures at N = 50 and N = 82. These analyses indicate that the binding energy of /sup 103/In is 1 MeV larger than predicted by the majority of the mass models. An examination of the Q/sub EC/ surface and the single- and two-neutron separation energies in the vicinity of /sup 103/ /sup 105/In is also performed to investigate further the deviation and other possible systematic variations in the mass surface in a model-independent way.

  16. Studies of decay properties of fission-product isotopes using the INEL ISOL facility

    International Nuclear Information System (INIS)

    Using the INEL ISOL facility, the authors are presently involved in a systematic study of the nuclear decay properties of neutron-rich rare-earth isotopes; with 252Cf as the source of fission products. In addition to use of traditional nuclear spectroscopic techniques, this study also involves use of a total absorption γ-ray spectrometer (TAGS) developed for direct-measurement of β-feeding (β-strength) distributions. A feature of this use of the TAGS system is that it provides information on the completeness of the level feeding information deduced from the nuclear spectroscopic measurements. Some results of this work, for the neutron-rich isotopes of Nd, Pm and Sm, are discussed

  17. Systematic study of heavy cluster emission from {210-226}^Ra isotopes

    CERN Document Server

    Santhosh, K P; Priyanka, B; Unnikrishnan, M S

    2012-01-01

    The half lives for various clusters lying in the cold reaction valleys of {210-226}^Ra isotopes are computed using our Coulomb and proximity potential model (CPPM). The computed half lives of 4^He and 14^C clusters from {210-226}^Ra isotopes are in good agreement with experimental data. Half lives are also computed using the Universal formula for cluster decay (UNIV) of Poenaru et al., and are found to be in agreement with CPPM values. Our study reveals the role of doubly magic 208^Pb daughter in cluster decay process. Geiger - Nuttall plots for all clusters up to 62^Fe are studied and are found to be linear with different slopes and intercepts. {12,14}^C emission from 220^Ra; 14^C emission from {222,224}^Ra; 14^C and 20^O emission from 226^Ra are found to be most favourable for measurement and this observation will serve as a guide to the future experiments.

  18. Recent studies to improve release properties from thick isotope separator on-line fission targets

    International Nuclear Information System (INIS)

    In the framework of the PARRNe program (Production d'Atomes Radioactifs Riches en Neutrons) of IPN Orsay, various techniques are currently used to characterize the release properties of elements of interest from a UCX target. On-line studies have been carried out with two plasma ion sources: a Nier-Bernas and a hot plasma ISOLDE-type (the ISOLDE collaboration kindly supplied us a MK5 ion source for these studies). In parallel, the analysis of the chemical and structure properties of some UCX samples as function of heating conditions has been carried out. Such data are essential to determine optimal conditions for the production of isotopes by the isotope separator on-line (ISOL) technique. First results are presented here for Kr and Ag. Investigations for other kinds of fission targets are planned

  19. The application of isotope dilution analysis to studies with optical enantiomorphs

    International Nuclear Information System (INIS)

    A brief description is given of studies on the racemization of individual amino-acids in intact protein by treatment with dilute alkali. Using C14-labelled protein, it was possible to measure the amount of this racemization by reverse isotope dilution analysis; of the amino-acids examined, serine exhibited the phenomenon to the greatest degree. Some figures are given indicating the applicability of this useful, but often neglected, method to various amino-acids. Minor variations in the combination of mixtures of d- and l-forms can also be conveniently observed by means of isotopic labelling, and this is illustrated by studies on 60/40 mixtures of the enantiomorphs of threomine and of valine. The behaviour of the amino-acid which forms a racemate is readily distinguished from the one that does not. (author)

  20. Decay studies and mass measurements on isobarically pure neutron-rich Hg and Tl isotopes

    CERN Multimedia

    Schweikhard, L C; Savreux, R P; Hager, U D K; Beck, D; Blaum, K

    2007-01-01

    We propose to perform mass measurements followed by $\\beta$- and $\\gamma$-decay studies on isobarically pure beams of neutron-rich Hg and Tl isotopes, which are very poorly known due to a large contamination at ISOL-facilities with surface-ionised francium. The aim is to study the binding energies of mother Hg and Tl nuclides, as well as the energies, spins and parities of the excited and ground states in the daughter Tl and Pb isotopes. The proposed studies will address a new subsection of the nuclear chart, with Z 126, where only 9 nuclides have been observed so far. Our studies will provide valuable input for mass models and shell-model calculations: they will probe the proton hole-neutron interaction and will allow to refine the matrix elements for the two-body residual interaction. Furthermore, they also give prospects for discovering new isomeric states or even new isotopes, for which the half-lives are predicted in the minute- and second-range.\\\\ To reach the isobaric purity, the experiments will be p...

  1. Studies about interaction of hydrogen isotopes with metals and intermetallic compounds

    International Nuclear Information System (INIS)

    Hydrogen is a nontoxic but highly inflammable gas. Compared to other inflammable gasses, its range of inflammability in air is much broader (4-74.5%) but it also vaporizes much more easily. Handling of hydrogen in form of hydrides enhances safety. Experiments with gaseous and liquid hydrogen should be performed in rooms with good ventilation. The interaction of hydrogen with metals and intermetallic compounds is a major field within physical chemistry. The essential feature of hydrogen-element system consists in the formation of chemical bond between hydrogen and metal atoms. The study of the interactions of hydride-forming metals and intermetallic compounds with heavy hydrogen isotopes -deuterium and tritium- offers new possibilities for investigating hydrogen behavior on surfaces and in a solid matrix. Using hydride-forming metals and intermetallic compounds, for example, recovery, purification and storage of heavy isotopes in tritium containing systems, can solve many problems arising in the nuclear-fuel cycle. The Nuclear Power Plant Cernavoda is equipped with a Canadian reactor of CANDU type. In the long term, Cernavoda area will be contaminated with on increasing quantity of tritium. In addition, the continuous contamination of heavy water from the reactor reduces the moderator's efficiency. For these reasons, ICSI - Rm. Valcea has developed a detritiation technology, based on catalytic isotopic exchange and cryogenic distillation. Tritium should be removed from the tritiated heavy water, and this will require the storage of tritium in a special vessel that can provide a high level of protection and safety of environment and personnel. Several metals have been studied as storage beds for hydrogen isotopes. One of the reference materials used for storing of hydrogen isotopes is uranium, a material with a great storage capacity, but unfortunately it is a radioactive metal and can react with the impurities in the stored gas. Other metals and alloys as ZrCo, Ti

  2. Isotopic study of the water exchange between atmosphere and biosphere at selected sites in Pakistan

    International Nuclear Information System (INIS)

    Study of water exchange between atmosphere and biosphere was initiated to understand the ties between these two spheres. Main objective of this study is to acquire sufficient environmental isotopic data for the exploration of water cycle dynamics in selected areas of Pakistan, in order to contribute to the IAEA global network for the development of regional scale model on ecosystems. Isotope investigations (18O, 2H) help evaluate the major processes such as photosynthesis, respiration and evapotranspiration. From January 2005 to April 2005 non woody plants (wheat, grass) and soil samples from wheat and grass fields (from the surface and 7cm below the surface) were collected. Moisture contents from these samples were extracted using the vacuum distillation method and analysed for hydrogen and oxygen isotope contents. Air moisture was also collected in the field. Woody plants consisting of eucalyptus, pine, delbergia sisso, melia azedarch were sampled from Islamabad. Seventeen more species of woody plants are included in the study, from another site, located near Lahore. Data depicts that the leaves of the wheat plant are more enriched in 18O and 2H than other parts of the same plant and grass. It may be due to the process of evapotranspiration which is more rapid from the wider leaves as compared to the small ones. Rain effect was also observed on δ18O and δ2H of the samples collected just two days after the rain event. Isotopic values of this rainwater were more negative as compared to other rain events that took place during this season. This depletion may be due to the 'continental effect' in precipitation. More than 200 samples from woody plants of different species and soil were collected. Isotopic data of the moisture extracted from leaves and stems of the plants of different species indicate that leaves of all the plants are more enriched in 2H and 18O than that of the respective stems. There also seem some considerable species-specific effects transforming

  3. Studies of osteoporosis in Croatia using isotope related techniques

    International Nuclear Information System (INIS)

    Pilot study was held to evaluate bone stiffness in children and adolescents in two districts of Croatia which, according to previous knowledge, differ in calcium intake. The relationship between habitual calcium intake and bone stiffness was determined. It was difficult and expensive to organise a transport of Istrian children to Zagreb in order to perform x-rays absorptiometry. Therefore, bone stiffness was determined with a portable ultrasound system. Bone mineral density (BMD) measurements were continued in subjects of both sex, across the age range 20-50 years from the central district of the city of Zagreb. Subjects were randomly selected from the demographic list. There is a tendency of BMD fall after the age of menopause in women. It appears that peak bone mass in women is obtained in the mid- 20s and In men at 30 years of age. The general conclusion about the trends observed In the population will be given after collection of all data. Calcium intake has an influence on peak bone mass, which becomes evident at the adolescent age. Children who had higher calcium intake had a higher bone mass, although that difference was not statistically significant That finding was more apparent in males. The calcium intake in Zagreb children was higher, so was the energy intake, but the mean body mass Index was identical, which indicates higher physical activity in children from Zagreb. Besides the calcium intake, the role of energy value of the food and habitual physical activities seem to be important in bone maturation

  4. High-yield expression of isotopically labeled peptides for use in NMR studies

    OpenAIRE

    Lindhout, Darrin A.; Thiessen, Angela; Schieve, Dean; Sykes, Brian D.

    2003-01-01

    Fusion protein constructs of the 56 amino acid globular protein GB-1 with various peptide sequences, coupled with the incorporation of a histidine tag for affinity purification, have generated high-yield fusion protein constructs. Methionine residues were inserted into the constructs to generate pure peptides following CNBr cleavage, yielding a system that is efficient and cost effective for isotopic labeling of peptides for NMR studies and other disciplines such as mass spectroscopy. Six pep...

  5. Isotope hydrology study of Kalamos region (Attiki) and of the Assopos river basin

    International Nuclear Information System (INIS)

    The isotopic composition of the water was used to determine the mechanism of recharge of the Assopos river basin and that of the Kalamos springs issuing brackish water near the coast. The results of the study permitted the catchment of the water before its salinization. A quantity of 73000 m3 per day is now pumped and used as additional drinkable water for the major area of Athens covering about the 1/6 of the corresponding mean daily consumption. (T.A.)

  6. Isotope techniques in catchment behaviour studies with particular emphasis on snowmelt runoff investigations

    International Nuclear Information System (INIS)

    The dynamics of runoff occurring mainly by snowmelt have been investigated by the aid of environmental isotopes. Regular samples collected from river water and snow cover throughout 1978 to 1981 at two selected catchment basins in eastern Turkey were analysed for their oxygen-18, deuterium and tritium contents. The tritium results together with detailed hydrological and hydro-meteorological data have enabled to study the time distribution of various component flow systems involved in the total runoff resulting from snowmelt

  7. Study of the downward movement of soil water in an unsaturated zone by using isotopic techniques

    International Nuclear Information System (INIS)

    Experiments carried out to study the contribution of infiltration from irrigated fields to the water-table have shown that the normal delta of irrigation water does not seem to have any appreciable effect on the water-table through heavy textured soil. However, the chemical analysis and isotopic contents of the sandy loam profile showed that the normal delta of irrigation water and rainfall does have some effect on the water-table. (author)

  8. Isotopes for improved management of nitrate pollution in aqueous resources: review of surface water field studies

    OpenAIRE

    NESTLER Angelika; BERGLUND Michael; Accoe, Frederik; Duta, Steluta; XUE Dongmei; Boeckx, Pascal; Taylor, Philip

    2011-01-01

    The aim of the European Union (EU) Marine Strategy Framework Directive (2008/56/EC) is to achieve good environmental status of the EU marine waters by 2020. This implies also that human-induced eutrophication should be minimised. Nitrogen and other nutrients cause eutrophication which means losses in biodiversity, ecosystem degradation, harmful algae blooming and oxygen deficiency in bottom waters. Studies showed that isotope analysis can be used as a tool to identify nitrogen sources and to ...

  9. Application of isotopic and chemical methods to the study of hydrological problems in Brazilian northeastern areas

    International Nuclear Information System (INIS)

    Hydrological studies are reported with samples of ground water from several region of northern - and northeastern Brazil: Marajo Island (State of Para), State of Piaui, Ceara and Rio Grande do Norte. A description is given of the utilization of chemical and isotopic methods, in particular measurements of tritium concentration and 14C- counting techniques for the determination of the origin and residence time of water. (I.C.R.)

  10. Microscopic insight in the study of yrast bands in selenium isotopes

    Indian Academy of Sciences (India)

    Parvaiz Ahmad Dar; Sonia Verma; Rani Devi; S K Khosa

    2008-05-01

    The yrast bands of even-even selenium isotopes with = 68-78 are studied in the framework of projected shell model, by employing quadrupole plus monopole and quadrupole pairing force in the Hamiltonian. The oblate and prolate structures of the bands have been investigated. The yrast energies, backbending plots and reduced 2 transition probabilities and -factors are calculated and compared with the experimental data. The calculated results are in reasonably good agreement with the experiments.

  11. Comparative international studies of osteoporosis using isotope techniques

    International Nuclear Information System (INIS)

    In-Vivo Neutron Activation Analysis (IVNAA) and Dual Energy X-ray Absorptiometry (DEXA) are routinely used in our laboratory for clinical and research investigation of Bone Mineral Content (BMC) and Bone Mineral Density (BMD in g/sq.cm). These two techniques differ in many respects. IVNAA is an established technique where 49Ca radioisotope induced by the 48Ca(n,gamma)49Ca reaction is measured to determine BMC. In DEXA, two X-rays of different energies are used and based on the known attenuation characteristics of bone and soft tissue and the measured attenuated signals, the BMC is calculated. Very little radiation dose (<0.1 mSv) is given in DEXA compared to IVNAA (3 to 5 mSv). Site specific information can be obtained in the former. Although DEXA is easier to use both the techniques are in use in the investigation of Osteopenia. The BMD, a clinical useful parameter, is a function of age and not height. The body calcium content determined by IVNAA is a function of height and not age. These differences are not yet clearly understood. Work is underway to determine the influence of several factors e.g. age, weight on BMD. We are also conducting experiments to determine the peak BMC and BMD of Canadians. The role of various life styles e.g. exercise, diet, ethnicity are being investigated as a determinant of BMD and BMC. Also the effects and safety of many drugs in the treatment of osteopenia and osteoporosis are also being studied. (author)

  12. Stable isotope studies. Final report, March 1, 1972--February 29, 1992

    Energy Technology Data Exchange (ETDEWEB)

    Ishida, T.

    1992-10-01

    The research has been in four general areas: (1) correlation of isotope effects with molecular forces and molecular structures, (2) correlation of zero-point energy and its isotope effects with molecular structure and molecular forces, (3) vapor pressure isotope effects, and (4) fractionation of stable isotopes. 73 refs, 38 figs, 29 tabs.

  13. Study of medical isotope production facility stack emissions and noble gas isotopic signature using automatic gamma-spectra analysis platform

    Science.gov (United States)

    Zhang, Weihua; Hoffmann, Emmy; Ungar, Kurt; Dolinar, George; Miley, Harry; Mekarski, Pawel; Schrom, Brian; Hoffman, Ian; Lawrie, Ryan; Loosz, Tom

    2013-04-01

    The nuclear industry emissions of the four CTBT (Comprehensive Nuclear-Test-Ban Treaty) relevant radioxenon isotopes are unavoidably detected by the IMS along with possible treaty violations. Another civil source of radioxenon emissions which contributes to the global background is radiopharmaceutical production companies. To better understand the source terms of these background emissions, a joint project between HC, ANSTO, PNNL and CRL was formed to install real-time detection systems to support 135Xe, 133Xe, 131mXe and 133mXe measurements at the ANSTO and CRL 99Mo production facility stacks as well as the CANDU (CANada Deuterium Uranium) primary coolant monitoring system at CRL. At each site, high resolution gamma spectra were collected every 15 minutes using a HPGe detector to continuously monitor a bypass feed from the stack or CANDU primary coolant system as it passed through a sampling cell. HC also conducted atmospheric monitoring for radioxenon at approximately 200 km distant from CRL. A program was written to transfer each spectrum into a text file format suitable for the automatic gamma-spectra analysis platform and then email the file to a server. Once the email was received by the server, it was automatically analysed with the gamma-spectrum software UniSampo/Shaman to perform radionuclide identification and activity calculation for a large number of gamma-spectra in a short period of time (less than 10 seconds per spectrum). The results of nuclide activity together with other spectrum parameters were saved into the Linssi database. This database contains a large amount of radionuclide information which is a valuable resource for the analysis of radionuclide distribution within the noble gas fission product emissions. The results could be useful to identify the specific mechanisms of the activity release. The isotopic signatures of the various radioxenon species can be determined as a function of release time. Comparison of 133mXe and 133Xe activity

  14. GEOTRACES: An international program to study the global marine biogeochemistry of trace elements and isotopes

    International Nuclear Information System (INIS)

    Full text: GEOTRACES is a collaborative multi-national program to investigate the global marine biogeochemical cycles of trace elements and their isotopes. It is supported by the Scientific Committee for Oceanographic Research (SCOR). Great advances in the analytical capabilities to measure trace elements and isotopes in the ocean have been made in the quarter century since the completion of GEOSECS, but much remains to be learned about the sources, transport, chemical speciation, biological availability, internal cycling and fate of the broad spectrum of trace elements and isotopes of interest to marine biogeochemists. Advances in chemical sensors, analytical instrumentation, and modeling make possible now research that could not have been envisioned even a decade ago. With the definition of a number of high priority research questions, and the availability of analytical techniques that permit sampling at high spatial and temporal density, the community of marine biogeochemists believes that the time is right to mount a major international research program to study the global marine biogeochemical cycles of trace elements and their isotopes. Developing a full understanding of the distribution and biogeochemical behaviour of trace elements and their isotopes (TEIs) in seawater has the potential to provide unique insights into a wide range of oceanic processes: role of micronutrients in controlling the oceanic productivity, mechanisms controlling the fate of contaminants, quantifying key processes regulating the marine carbon cycle, insight into the mean velocity field and mixing processes in the ocean on very slow timescales, and paleo-oceanographic proxies. The primary objectives for the GEOTRACES program are: - To determine global distributions of selected TEIs in the ocean; - To evaluate the oceanic sources, sinks, and internal cycling of these TEIs and thereby characterize more completely their global biogeochemical cycles; - To build and maintain a core

  15. GEOTRACES : An international program to study the global marine biogeochemistry of trace elements and isotopes

    International Nuclear Information System (INIS)

    Full text: GEOTRACES is a collaborative multi-national program to investigate the global marine biogeochemical cycles of trace elements and their isotopes. It is supported by the Scientific Committee for Oceanographic Research (SCOR). Great advances in the analytical capabilities to measure trace elements and isotopes in the ocean have been made in the quarter century since the completion of GEOSECS, but much remains to be learned about the sources, transport, chemical speciation, biological availability, internal cycling and fate of the broad spectrum of trace elements and isotopes of interest to marine biogeochemists. Advances in chemical sensors, analytical instrumentation, and modeling make possible now research that could not have been envisioned even a decade ago. With the definition of a number of high priority research questions, and the availability of analytical techniques that permit sampling at high spatial and temporal density, the community of marine biogeochemists believes that the time is right to mount a major international research program to study the global marine biogeochemical cycles of trace elements and their isotopes. Developing a full understanding of the distribution and biogeochemical behaviour of trace elements and their isotopes (TEIs) in seawater has the potential to provide unique insights into a wide range of oceanic processes: role of micronutrients in controlling the oceanic productivity, mechanisms controlling the fate of contaminants, quantifying key processes regulating the marine carbon cycle, insight into the mean velocity field and mixing processes in the ocean on very slow timescales, and paleo-oceanographic proxies. The primary objectives for the GEOTRACES program are: 1) To determine global distributions of selected TEIs in the ocean; 2) To evaluate the oceanic sources, sinks, and internal cycling of these TEIs and thereby characterize more completely their global biogeochemical cycles; 3) To build and maintain a core

  16. Nuclear shape coexistence in Po isotopes: An interacting boson model study

    CERN Document Server

    Garcia-Ramos, J E

    2015-01-01

    Background: The lead region, Po, Pb, Hg, and Pt, shows up the presence of coexisting structures having different deformation and corresponding to different particle-hole configurations in the Shell Model language. Purpose: We intend to study the importance of configuration mixing in the understanding of the nuclear structure of even-even Po isotopes, where the shape coexistence phenomena are not clear enough. Method: We study in detail a long chain of polonium isotopes, 190-208Po, using the interacting boson model with configuration mixing (IBM-CM). We fix the parameters of the Hamiltonians through a least-squares fit to the known energies and absolute B(E2) transition rates of states up to 3 MeV. Results: We obtained the IBM-CM Hamiltonians and we calculate excitation energies, B(E2)'s, electric quadrupole moments, nuclear radii and isotopic shifts, quadrupole shape invariants, wave functions, and deformations. Conclusions: We obtain a good agreement with the experimental data for all the studied observables...

  17. Photon strength functions in Gd isotopes studied from radiative capture of resonance neutrons

    Directory of Open Access Journals (Sweden)

    Kroll J.

    2014-04-01

    Full Text Available The experimental spectra of γ rays following radiative neutron capture on isolated resonances of stable 152,154–158Gd targets were measured by the DANCE calorimeter installed at the Los Alamos Neutron Scattering Center in New Mexico, USA. These spectra were analyzed within the extreme statistical model to get new information on the photon strength functions. Special emphasis was put on study of the scissors vibrational mode present in these isotopes. Our data show that the scissors-mode resonances are built not only on the ground states but also on the excited levels of all studied Gd isotopes. The scissors mode strength observed in 157,159Gd products is significantly higher than in neighboring even-even nuclei 156,158Gd. Such a difference indicates the existence of an odd-even effect in the scissors mode strength. Moreover, there exists no universal parameter-free model of the electric dipole photon strength function describing the experimental data in all of the Gd isotopes studied. The results for the scissors mode are compared with the (γ, γ′ data for the ground-state transitions and with the results from 3He-induced reactions.

  18. Feasibility study on the medical isotopes production with solution target using OSTR: (99)Mo and related isotopes

    Science.gov (United States)

    Baik, Seung-Hyuk

    1999-11-01

    Molybdenum-99 (99Mo) is the parent nuclide of Technetium-99m (99mTc), a radioisotope which is widely used in nuclear medicine. 99Mo is produced from the fission of 235U or the irradiation of 98Mo. This study shows the feasibility of the using an 'aqueous homogeneous uranium solution target' for the production of a medical isotope, 99Mo. Some of the advantages that the solution target has over a solid target include the inherent reactor safety features offered by large negative temperature and power reactivity coefficients, the fabrication convenience, the straightforward extraction process, and a low volume of waste generated. To evaluate the core configuration and the production rate of 99Mo, a three-dimensional model of the Oregon State University TRIGA Reactor (OSTR) core was developed for use with the Monte Carlo N-Particle Transport Code (MCNP) and then verified by comparing with the measured values. Two values are in good agreement within one percent in the keffective values calculated. Two types of solution targets are analyzed for the OSTR. The first one has the same outer-dimensions as an OSTR fuel element but is filled with a uranium solution. The other is the continuous flow target system (CFTS) like solution fuel reactors. Uranyl nitrate and uranyl sulfate solutions enriched to 20% or 93% are investigated as a target material without raising any safety concern to the OSTR operation. A seven-day irradiation of ten tube-type-93% enriched uranyl nitrate solution targets would produce 43% of the 99Mo required in the US for one week. The CFTS would generate 31% of the required 99Mo in a 7-day cycle. The conceptual chemical extraction processes for irradiated solution targets are developed. This work also includes an analysis of nuclear safety issues such as the radiolytic gas, thermal hydraulics, the waste, and the radiological impacts of an accident. The production of 99Mo in the OSTR with the uranium solution is technically feasible as demonstrated in this

  19. Isotope ratio determinations by inductively coupled plasma/mass spectrometry for zinc bioavailability studies

    International Nuclear Information System (INIS)

    A method is described for the measurement of 67Zn/68Zn and 70Zn/68Zn ratios by inductively coupled plasma/mass spectrometry with ultrasonic nebulization. The method provides sufficient accuracy and precision for zinc bioavailability studies that use samples of human feces or blood plasma. Extraction of zinc from ashed samples yields aqueous solutions sufficiently devoid of matrix ions that could affect count rates and isotope ratios. Effects of sodium matrix, zinc concentration, and instrumental parameters on the precision of isotope ratio determinations are documented. Additions of spikes enriched in 67Zn and 70Zn to natural-abundance fecal samples verify that ratios can be determined on solutions 30 μM in zinc (70Zn and to 84 atom% excess of 67Zn. (Auth.)

  20. Study of the mechanism of diatom cell division by means of 29Si isotope tracing

    International Nuclear Information System (INIS)

    Diatoms are delicate unicellular organisms enclosed in a silica frustule, that is made up of two valves. Multiplication of the diatoms occurs by ordinary mitotic cell division. During cell division each cell produces two daughter cells, each of them keeping one of the two valves of the mother cell and producing a new valve by absorbing the silicon present in the environment. The NanoSIMS 50 allows ion imaging to be performed on diatoms in order to determine the site of fixation of silicon. The aim of this study was to observe and compare the mechanism of the construction of the new valve after cell division. To this end, different types of diatoms have been transferred in a culture medium enriched with 29Si and after several days, the distribution of the different isotopes of silicon has been determined by NanoSIMS50 imaging. The construction of new valves has been observed and the isotopic ratio has been determined

  1. Groundwater recharge studies in Maharashtra. Development of isotope techniques and field experience

    International Nuclear Information System (INIS)

    Some regional groundwater recharge investigations both in hard rock and in alluvial areas were carried out in the State of Maharashtra, India, by using isotope techniques. A simple stable isotope approach was evolved and applied in an investigation on the extent of artificial recharge in the command area of Shindawane percolation tank in the Pune district. A similar investigation in the Bhangarwadi percolation tank in the Osmanabad district was made using radioactive tracers. A method for the in-situ determination of soil-moisture transport rates using K360Co(CN)6 as tracer has been proposed, which compares well with the tritiated water method in laboratory investigations, and the results obtained in the limited field studies carried out in the Tapti-Purna alluvial tract are promising. (author)

  2. Groundwater recharge studies in Maharashtra development of isotope techniques and field experience

    International Nuclear Information System (INIS)

    Some regional groundwater recharge investigations both in hard rock and alluvial areas have been carried out using isotope techniques in the State of Maharashtra, India. A simple stable isotope approach has been evolved and applied in an investigation on the extent of artificial recharge in the command area of Shindawane Percolation Tank in the Pune district. A similar investigation in the Bangarwadi Percolation Tank in the Osmanabad district has been made using radioactive tracers. A method for the 'in situ' determination of soil moisture transport rates using K360Co(CN)6 as tracer has been proposed. The method compares well with the triated water method in laboratory investigations and the results obtained in the limited field studies carried out in the Tapti-Purna alluvial tract are promising. (orig.)

  3. A study of stable isotopic variations of Antarctic snow by albedo differences

    Science.gov (United States)

    Lee, Jeonghoon; Han, Yeongcheol; Ham, Ji-Young; Kim, Young-Hee; Kim, Songyi; Kim, Hyerin; Na, Un-Sung

    2015-04-01

    Snow's albedo can be decreased if there are any impurities on the snow surface other than snow itself. Due to the decrease of albedo of snow, melting rates of surface snow can be enhanced, which is very crucial in climate change and hydrogeology in many parts of the world. Anthropogenic black carbons caused by the incomplete combustion of fossil fuel affect on snow and tephra particles generated by geologic volcanic activities reduce snow albedo. In this study, we investigated isotopic compositions between snow covered by tephra particles and clean snow. Isotopic compositions of snow with tephra statistically shows more enriched than those of clean snow (pclimate change and hydrogeology. To quantitatively explain these observations, melting experiments and numerical approaches are required.

  4. Preparation and characterisation of isotopically enriched Ta2O5 targets for nuclear astrophysics studies

    International Nuclear Information System (INIS)

    The direct measurement of reaction cross-sections at astrophysical energies often requires the use of solid targets of known thickness, isotopic composition, and stoichiometry that are able to withstand high beam currents for extended periods of time. Here, we report on the production and characterisation of isotopically enriched Ta2O5 targets for the study of proton-induced reactions at the Laboratory for Underground Nuclear Astrophysics facility of the Laboratori Nazionali del Gran Sasso. The targets were prepared by anodisation of tantalum backings in enriched water (up to 66% in 17O and up to 96% in 18O). Special care was devoted to minimising the presence of any contaminants that could induce unwanted background reactions with the beam in the energy region of astrophysical interest. Results from target characterisation measurements are reported, and the conclusions for proton capture measurements with these targets are drawn. (orig.)

  5. Preparation and characterisation of isotopically enriched Ta$_2$O$_5$ targets for nuclear astrophysics studies

    CERN Document Server

    Caciolli, A; Di Leva, A; Formicola, A; Aliotta, M; Anders, M; Bellini, A; Bemmerer, D; Broggini, C; Campeggio, M; Corvisiero, P; Depalo, R; Elekes, Z; Fülöp, Zs; Gervino, G; Guglielmetti, A; Gustavino, C; Gyürky, Gy; Imbriani, G; Junker, M; Marta, M; Menegazzo, R; Napolitani, E; Prati, P; Rigato, V; Roca, V; Rolfs, C; Alvarez, C Rossi; Somorjai, E; Salvo, C; Straniero, O; Strieder, F; Szücs, T; Terrasi, F; Trautvetter, H P; Trezzi, D

    2012-01-01

    The direct measurement of reaction cross sections at astrophysical energies often requires the use of solid targets of known thickness, isotopic composition, and stoichiometry that are able to withstand high beam currents for extended periods of time. Here, we report on the production and characterisation of isotopically enriched Ta$_2$O$_5$ targets for the study of proton-induced reactions at the Laboratory for Underground Nuclear Astrophysics facility of the Laboratori Nazionali del Gran Sasso. The targets were prepared by anodisation of tantalum backings in enriched water (up to 66% in $^{17}$O and up to 96% in $^{18}$O). Special care was devoted to minimising the presence of any contaminants that could induce unwanted background reactions with the beam in the energy region of astrophysical interest. Results from target characterisation measurements are reported, and the conclusions for proton capture measurements with these targets are drawn.

  6. Isotopic and chemical studies of geothermal waters of Northern Areas in Pakistan

    International Nuclear Information System (INIS)

    Northern Areas is one of the major thermal fields of Pakistan with more than two dozen known hot springs having discharge temperature ranging from 35 deg. C to 94 deg. C. Isotopic and chemical techniques applied to study the geothermal fields show that thermal waters are of meteoric origin and can be classified as Na-HCO3, Na-SO4 and mixed type on the basis of their chemical contents. At some places cooling of thermal waters seems to be due to steam separation whereas mixing with fresh cold water is prominent at the remaining sites. The temperatures estimated by isotopic and chemical geothermometers for the two major fields i.e. Tatta Pani and Murtazabad are 83-257 deg. C and 65-296 deg. C respectively. (author). 24 refs, 11 figs, 3 tabs

  7. Efficacy of cranking technique in the study of some neutron-deficient neodymium isotopes

    International Nuclear Information System (INIS)

    In the present work, the results of calculations on various nuclear structure quantities in even-even neutron-deficient 130-136Nd using Cranked Hatree-Fock Bogoliubov (CHFB) technique have been presented. The various nuclear structure quantities that have been calculated in 130-136Nd isotopes are the yrast spectra, subshell occupation probabilities of various valence orbits and intrinsic quadrupole moments. Besides this, a comparative study of the calculated yrast spectra with the available experimental data as well as with the results of calculations obtained by R.K. Bhat et al. using Variation After Projection (VAP) technique on the same neutron-deficient 130-136Nd isotopes has also been presented

  8. Charge radii of magnesium isotopes by laser spectroscopy a structural study over the $sd$ shell

    CERN Multimedia

    Schug, M; Krieger, A R

    We propose to study the evolution of nuclear sizes and shapes over the magnesium chain by measuring the root-mean-square charge radii of $^{21 - 32}$Mg, essentially covering the entire $\\textit{sd}$ shell. Our goal is to detect the structural changes, which in the neutron-deficient isotopes may originate from clustering, in a way similar to neon, and on the neutron-rich side would characterize the transition to the "island of inversion". We will combine, for the first time, the sensitive $\\beta$-detection technique with traditional fluorescence spectroscopy for isotope-shift measurements and in such a way gain access to the exotic species near the ${N}$ = 8 and ${N}$ = 20 shell closures.

  9. Involving GLOBE schools in a study of the stable isotope composition of precipitation in Croatia

    International Nuclear Information System (INIS)

    Karst is characterized by high permeability, Kporosity and crevices in which water moves in complex subterranean networks. Therefore, water resources in karst areas are very sensitive to pollution. This is of particular significance for Croatia, since about 50% of the country is karst, and the country's water management is a national priority. It is thus of vital interest to have as complete as possible knowledge of all factors which have input into the water system, including precipitation. Besides meteorological data, isotopic tracers are important tools to understand and quantify this complex problem. The isotopic composition of water is determined primarily by the passage of water into and through the atmosphere; the imprint on water bodies through precipitation forms the basis of many hydrological studies. It is usually expressed by abundance ratios R for 2H/1H and 18O/16O, respectively

  10. Tracing the pathways of neotropical migratory shorebirds using stable isotopes: a pilot study.

    Science.gov (United States)

    Farmer, A; Rye, R; Landis, G; Bern, C; Kester, C; Ridley, I

    2003-09-01

    We evaluated the potential use of stable isotopes to establish linkages between the wintering grounds and the breeding grounds of the Pectoral Sandpiper (Calidris melanotos), the White-rumped Sandpiper (Calidris fuscicollis), the Baird's Sandpiper (Calidris bairdii), and other Neotropical migratory shorebird species (e.g., Tringa spp.). These species molt their flight feathers on the wintering grounds and hence their flight feathers carry chemical signatures that are characteristic of their winter habitat. The objective of our pilot study was to assess the feasibility of identifying the winter origin of individual birds by: (1) collecting shorebird flight feathers from several widely separated Argentine sites and analyzing these for a suite of stable isotopes; and 2) analyzing the deuterium and 18O isotope data that were available from precipitation measurement stations in Argentina. Isotopic ratios (delta13C, delta15N and delta34S) of flight feathers were significantly different among three widely separated sites in Argentina during January 2001. In terms of relative importance in separating the sites, delta34S was most important, followed by delta15N, and then delta13C. In the complete discriminant analysis, the classification function correctly predicted group membership in 85% of the cases (jackknifed classification matrix). In a stepwise analysis delta13C was dropped from the solution, and site membership was correctly predicted in 92% of cases (jackknifed matrix). Analysis of precipitation data showed that both deltaD and delta18O were significantly related to both latitude and longitude on a countrywide scale (p Argentina. There was unexplained variation in isotope ratios within and among the different wing feathers from individual birds. Such variation may indicate that birds are not faithful to a local site during their winter stay in Argentina. There was significant interannual variation in the deltaD and delta18O of precipitation. Hence, specific

  11. Nuclear structure studies of the neutron-rich Rubidium isotopes using Coulomb excitation

    CERN Multimedia

    Reiter, P; Blazhev, A A; Voulot, D; Meot, V H; Simpson, G S; Georgiev, G P; Gaudefroy, L; Roig, O

    We propose to study the properties of odd-mass neutron-rich rubidium isotopes by the Coulomb-excitation technique, using the Miniball array coupled to the REX-ISOLDE facility. The results from similar measurements from the recent years (e.g. for the odd-mass and the odd-odd Cu isotopes, IS435) have shown the strong potential in such measurements for gaining information both for single-particle-like and collective states in exotic nuclei. Since there is practically no experimental information for excited states in the odd-mass Rb isotopes beyond $^{93}$Rb, the present study should be able to provide new data in a region of spherical ($^{93}$Rb and $^{95}$Rb) as well as well-deformed nuclei ($^{97}$Rb and $^{99}$Rb). Of particular interest is the rapid shape change that occurs when going from $^{95}$Rb (${\\varepsilon}_{2}$=0.06) to $^{97}$Rb (${\\varepsilon}_{2}$=0.3). These results should be of significant astrophysical interest as well, due to the close proximity of the r-process path.

  12. Studying the Permian cross-section (Volga region) using chemical and isotopic investigations

    Science.gov (United States)

    Gareev, Bulat; Georgii, Batalin; Nurgaliev, Danis; Nurgalieva, Nuriya

    2016-04-01

    This paper presents a study of international important site: the cross-section of Permian system's Urzhumian Stage in the ravine "Pechischy". Outcrop is located on the right bank of the Volga River (about 10 km West of Kazan). It has local, regional and planetary correlation features and also footprints of different geographical scale events. The main objective in the research is the deep study of sediments using chemical and isotopic investigations. XRF spectrometer was used for chemical investigations of samples. Chemistry of carbonates and clastic rocks includes the analysis of chemical elements, compounds, petrochemical (lithogeochemical) modules for the interpretation of the genesis of lithotypes. For the review of the geochemistry of stable isotopes of carbon (oxygen) we used IRMS. The main objective is the nature of the isotope fractionation issues, to addressing the issues of stratigraphy and paleogeography. The measurements have shown the variability of chemical parameters in cross-section. It gives us opportunity to see small changes in sedimentation and recognize the factors that influence to the process. The work was carried out according to the Russian Government's Program of Competitive Growth of Kazan Federal University, supported by the grant provided to the Kazan State University for performing the state program in the field of scientific research.

  13. Final Progress Report: Isotope Identification Algorithm for Rapid and Accurate Determination of Radioisotopes Feasibility Study

    Energy Technology Data Exchange (ETDEWEB)

    Rawool-Sullivan, Mohini [Los Alamos National Laboratory; Bounds, John Alan [Los Alamos National Laboratory; Brumby, Steven P. [Los Alamos National Laboratory; Prasad, Lakshman [Los Alamos National Laboratory; Sullivan, John P. [Los Alamos National Laboratory

    2012-04-30

    This is the final report of the project titled, 'Isotope Identification Algorithm for Rapid and Accurate Determination of Radioisotopes,' PMIS project number LA10-HUMANID-PD03. The goal of the work was to demonstrate principles of emulating a human analysis approach towards the data collected using radiation isotope identification devices (RIIDs). It summarizes work performed over the FY10 time period. The goal of the work was to demonstrate principles of emulating a human analysis approach towards the data collected using radiation isotope identification devices (RIIDs). Human analysts begin analyzing a spectrum based on features in the spectrum - lines and shapes that are present in a given spectrum. The proposed work was to carry out a feasibility study that will pick out all gamma ray peaks and other features such as Compton edges, bremsstrahlung, presence/absence of shielding and presence of neutrons and escape peaks. Ultimately success of this feasibility study will allow us to collectively explain identified features and form a realistic scenario that produced a given spectrum in the future. We wanted to develop and demonstrate machine learning algorithms that will qualitatively enhance the automated identification capabilities of portable radiological sensors that are currently being used in the field.

  14. Quantum Dynamics Study of the Isotopic Effect on Capture Reactions: HD, D2 + CH3

    Science.gov (United States)

    Wang, Dunyou; Kwak, Dochan (Technical Monitor)

    2002-01-01

    Time-dependent wave-packet-propagation calculations are reported for the isotopic reactions, HD + CH3 and D2 + CH3, in six degrees of freedom and for zero total angular momentum. Initial state selected reaction probabilities for different initial rotational-vibrational states are presented in this study. This study shows that excitations of the HD(D2) enhances the reactivities; whereas the excitations of the CH3 umbrella mode have the opposite effects. This is consistent with the reaction of H2 + CH3. The comparison of these three isotopic reactions also shows the isotopic effects in the initial-state-selected reaction probabilities. The cumulative reaction probabilities (CRP) are obtained by summing over initial-state-selected reaction probabilities. The energy-shift approximation to account for the contribution of degrees of freedom missing in the six dimensionality calculation is employed to obtain approximate full-dimensional CRPs. The rate constant comparison shows H2 + CH3 reaction has the biggest reactivity, then HD + CH3, and D2 + CH3 has the smallest.

  15. Sr isotopic characteristics in two small watersheds draining typical silicate and carbonate rocks: implication for the studies on seawater Sr isotopic evolution

    Science.gov (United States)

    Wu, W. H.; Zheng, H. B.; Yang, J. D.

    2013-06-01

    We systematically investigated Sr isotopic characteristics of small silicate watershed - the tributary Xishui River of the Yangtze River, and small carbonate watershed - the tributary Guijiang River of the Pearl River. The results show that the Xishui River has relatively high Sr concentrations (0.468-1.70 μmol L-1 in summer and 1.30-3.17 μmol L-1 in winter, respectively) and low 87Sr/86Sr ratios (0.708686-0.709148 in summer and 0.708515-0.709305 in winter), which is similar to the characteristics of carbonate weathering. The Guijiang River has low Sr concentrations (0.124-1.098 μmol L-1) and high 87Sr/86Sr ratios (0.710558-0.724605), being characterized by silicate weathering. In the Xishui River catchment, chemical weathering rates in summer are far higher than those in winter, indicating significant influence of climate regime. However, slight differences of 87Sr/86Sr ratios between summer and winter show that influence of climate on Sr isotope is uncertainty owing to very similar Sr isotope values in silicate and carbonate bedrocks. As 87Sr/86Sr ratios in the Xishui River are lower than those in seawater, they will decrease 87Sr/86Sr ratio of seawater after transported into oceans. Previous studies also showed that some basaltic watersheds with extremely high chemical weathering rates reduced the seawater Sr isotope ratios. In other words, river catchments with high silicate weathering rates do not certainly transport highly radiogenic Sr into oceans. Therefore, it may be questionable that using the variations of seawater 87Sr/86Sr ratio to indicate the continental silicate weathering intensity. In the Guijiang River catchment, 87Sr/86Sr ratios of carbonate rocks and other sources (rainwater, domestic and industrial waste water, and agricultural fertilizer) are lower than 0.71. In comparison, some non-carbonate components, such as, sand rocks, mud rocks, shales, have relatively high Sr isotopic compositions. Moreover, granites accounted for only 5% of the

  16. Laser-spectroscopic nuclear-structure studies on radioactive silver and indium isotopes

    International Nuclear Information System (INIS)

    Neutron-deficient silver and neutron-rich indium isotopes were studied by collinear laser spectroscopy. The neutron-deficient nuclei 101,103,104,105,105m,106mAg were produced as evaporation-residual nuclei in heavy-ion fusion reactions at the mass separator of the GSI in Darmstadt. The fourteen studied indium isotopes and isomers with even mass number in the range 112-126In were produced by 600-MeV-proton induced fission of a uranium carbide target at the ISOLDE separator in Geneva. The mass-separated ion beam was subsequently deviated electrostatically, neutralized in a sodium vapor and superposed with a cw dye laser. A photon counting system detected the resonance fluorescence of the induced transitions. The hyperfine structure and the isotope shift of the 4d95s22D5/2 → 4d106p2P3/2 transition (λ=547.7 nm) in silver and the 5p2P1/2,3/2 → 6s2s1/2 transition (λ=410 respectively 451 nm) in indium were measured. While in indium for the analysis of the data earlier work could be referred to, in silver a detailed analysis of the isotope shift and hyperfine structure was performed by means of ab initio calculations and semi-empirical procedures. Thereby the configuration interactions were especially considered. The nuclear moments were discussed in the framework of existing nuclear models regarding nuclear-spectroscopic informations. (orig./HSI)

  17. Inductively coupled plasma mass spectrometry for stable isotope metabolic tracer studies of living systems

    Energy Technology Data Exchange (ETDEWEB)

    Luong, E.

    1999-05-10

    This dissertation focuses on the development of methods for stable isotope metabolic tracer studies in living systems using inductively coupled plasma single and dual quadrupole mass spectrometers. Sub-nanogram per gram levels of molybdenum (Mo) from human blood plasma are isolated by the use of anion exchange alumina microcolumns. Million-fold more concentrated spectral and matrix interferences such as sodium, chloride, sulfate, phosphate, etc. in the blood constituents are removed from the analyte. The recovery of Mo from the alumina column is 82 {+-} 5% (n = 5). Isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS) is utilized for the quantitative ultra-trace concentration determination of Mo in bovine and human blood samples. The average Mo concentration in reference bovine serum determined by this method is 10.2 {+-} 0.4 ng/g, while the certified value is 11.5 {+-} 1.1 ng/g (95% confidence interval). The Mo concentration of one pool of human blood plasma from two healthy male donors is 0.5 {+-} 0.1 ng/g. The inductively coupled plasma twin quadrupole mass spectrometer (ICP-TQMS) is used to measure the carbon isotope ratio from non-volatile organic compounds and bio-organic molecules to assess the ability as an alternative analytical method to gas chromatography combustion isotope ratio mass spectrometry (GC-combustion-IRMS). Trytophan, myoglobin, and {beta}-cyclodextrin are chosen for the study, initial observation of spectral interference of {sup 13}C{sup +} with {sup 12}C{sup 1}H{sup +} comes from the incomplete dissociation of myoglobin and/or {beta}-cyclodextrin.

  18. Isotope and geochemical study of the geothermal fields of Chios Island, Greece

    International Nuclear Information System (INIS)

    Full text: The study area is located in the west part of Aegean sea, in the Chios Island. Chios is characterised by a strong geothermal activity especially in the area of Aghia Eleni and Agiasmata where the temperature ranges from 26 - 54 deg. C. In the framework of a 1998-2001 bilateral research programme between Italy and Greece, geochemical and isotope investigations were conducted on spring and water wells of Chios in order to improve the knowledge on the geothermal potential of the island. A number of hydrothermal manifestations were found in the northern and southeastern parts of the island, namely in the areas of Nenita-Thimiana, Patrika, Aghia Eleni and Aghiasmata. In the plain of Nenita the outcropping formation is entirely constituted of neogene fluvio-lacustrine deposits which act as the impervious cover of the underlying hydrothermal acquifer. The springs of Aghiasmata issue from the lower-middle Miocene volcanic formations. Groundwater samples from boreholes and springs were collected and analysed for major cations and anions (Cl-, NO3-, SO42-, Na+, K+, Ca2+ and Mg2+), for stable isotopes of water (18O and D), and aqueous sulphate [18O(SO42-) and 34S]. Moreover temperature, conductivity and pH are measured in the field. A study of ionic and isotopic contents shows that thermal springs (Aghia Eleni and Aghiasmata) of Chios Island are fed by seawater. In the case of Aghia Eleni the big marine contribution (89%) disturbs the chemical and isotopic geothermometers. In the case of Aghiasmata the geothermometers suggested equilibrium temperature near 200 deg. C. For the boreholes of the southern part of the island the initial temperature is estimated in the order of 80-90 deg. C. (author)

  19. Productions and interests of the radiopharmaceuticals labelled by 11C, 13N, 15O, and 18F

    International Nuclear Information System (INIS)

    As medical diagnosis methods based on the use of short-life radioelements such as carbon-11, nitrogen-13, oxygen-15 and fluorine-18 have been developed, these four radio-isotopes are notably adapted to external detection by tomography. Besides, due to their short period, their radioactive concentration per mass unity is very high. In the first part of this research thesis, the author presents the characteristics of these four radio-isotopes, describes the operation of cyclotrons and the principles, benefits, drawbacks, and types of positron emission tomography. The second part addresses the production of the radionuclides and precursors, the production of radiopharmaceutical products (haemoglobin, sugars, amino acids, fatty acids, steroid marking, and drug marking). The third part reports some studies illustrating the pharmaceutical interest of these radioelements

  20. Isotopic discrimination of stable isotopes of nitrogen (delta N-15) and carbon (delta C-13) in a host-specific holocephalan tapeworm

    Czech Academy of Sciences Publication Activity Database

    Navarro, J.; Albo-Puigserver, M.; Coll, M.; Saez, R.; Forero, M. G.; Kuchta, Roman

    2014-01-01

    Roč. 88, č. 3 (2014), s. 371-375. ISSN 0022-149X Institutional support: RVO:60077344 Keywords : food webs * fractionation * Gyrocotylidea * parasites * ecology * cercomeromorpha * Platyhelminthes * cercomeria * community * patterns Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 1.421, year: 2014