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Sample records for carbon 14 compounds

  1. Improved quality control of carbon-14 labelled compounds

    International Nuclear Information System (INIS)

    IUT Ltd is a producer of carbon-14 labelled organic compounds like benzene, methanol, phenol, formaldehyde, Na-acetates and also special ordered compounds. The quality control of these compounds is carried out by means of HPLC and GC-MS due to chemical purity. Molar activity was determined by Liquid Scintillation Counting and HPLC being equipped by a radioactivity detector. Unfortunately the accuracy of the activity determination was arrived only ±4% relatively. This error is too high because of the large dilution factors. In respect of the IUT accreditation as an analytical laboratory in Germany the accuracy had to be improved remarkably. Therefore the GC-MS-determination of molar activities of labelled compounds is used as the 14C-labelled compound. A special evaluation code is used to determine the enrichment values relative to the unlabelled molecules. Taking into account the results of GC-MS the accuracy of molar activity determination is improved to ±2%. The spectra evaluation is demonstrated and some examples are discussed

  2. Differential monitoring of tritium and carbon-14 compounds

    International Nuclear Information System (INIS)

    A gaseous sampling system was developed to differentially collect all major volatile forms of tritium and carbon-14 according to chemical class. These chemical forms include: tritiated forms of water, hydrogen and organics; as well as 14C-containing carbon monoxide, carbon dioxide and organics. Sampling campaigns involving the use of this differential 3H and 14C collection system have been successfully conducted at a high level liquid waste solidification plant, at a spent fuel storage facility and in the vicinity of power reactors

  3. Carbon-14 waste management

    International Nuclear Information System (INIS)

    Carbon-14 occurs in nature, but is also formed in nuclear reactors. Because of its long half-life and the biological significance of carbon, releases from nuclear facilities could have a significant radiological impact. Waste management strategies for carbon-14 are therefore of current concern. Carbon-14 is present in a variety of waste streams both at reactors and at reprocessing plants. A reliable picture of the production and release of carbon-14 from various reactor systems has been built up for the purposes of this study. A possible management strategy for carbon-14 might be the reduction of nitrogen impurity levels in core materials, since the activation of 14N is usually the dominant source of carbon-14. The key problem in carbon-14 management is its retention of off-gas streams, particularly in the dissolver off-gas stream at reprocessing plants. Three alternative trapping processes that convert carbon dioxide into insoluble carbonates have been suggested. The results show that none of the options considered need be rejected on the grounds of potential radiation doses to individuals. All exposures should be as low as reasonably achievable, economic and social factors being taken into account. If, on these grounds, retention and disposal of carbon-14 is found to be beneficial, then, subject to the limitations noted, appropriate retention, immobilization and disposal technologies have been identified

  4. Study of carbon nitride compounds synthesised by co-implantation of 13C and 14N in copper at different temperatures

    International Nuclear Information System (INIS)

    Research highlights: → Simultaneous implantation of 13C and 14N in copper were performed to synthesise CNx compounds. → The formation of fullerene-like CNx compounds was highlighted by XPS and TEM. → Only about 20% of the implanted 14N atoms are contained in the FL CxNy structures. → The exceeding of implanted nitrogen precipitates in large N2 gas bubbles. → A growth model for the FL CxNy structures is proposed. - Abstract: Carbon nitride compounds have been synthesised in copper by simultaneous high fluence (1018 at. cm-2) implantation of 13C and 14N ions. During the implantation process, the substrate temperature was maintained at 25, 250, 350 or 450 deg. C. Depth profiles of 13C and 14N were determined using the non-resonant nuclear reactions (NRA) induced by a 1.05 MeV deuteron beam. The retained doses were deduced from NRA measurements and compared to the implanted fluence. The chemical bonds between carbon and nitrogen were studied as a function of depth and temperature by X-ray photoelectron spectroscopy (XPS). The curve fitting of C 1s and N 1s core level photoelectron spectra reveal different types of C-N bonds and show the signature of N2 molecules. The presence of nitrogen gas bubbles in copper was highlighted by mass spectroscopy. The structure of carbon nitride compounds was characterised by transmission electron microscopy (TEM). For that purpose, cross-sectional samples were prepared using a focused ion beam (FIB) system. TEM observations showed the presence of small amorphous carbon nitride 'nano-capsules' and large gas bubbles in copper. Based on our observations, we propose a model for the growth of these nano-objects. Finally, the mechanical properties of the implanted samples were investigated by nano-indentation.

  5. Chemical separation of carbon -14 in radwastes

    International Nuclear Information System (INIS)

    Carbon-14 has a long half-life of 5730 years and decays by beta emission of 156KeV to the stable nuclide, Nitrogen-14. Carbon-14 is produced mostly by the neutron activation of naturally occurring oxygen-17 in water molecules of the reactor coolant and Nitrogen-14 from nitrogen gas dissolved in the reactor coolant. Most of these carbon-14 are known to be discharged as gaseous wastes. The chemical forms of the gaseous emissions of carbon-14 from PWR stations range from 10∼26% as 14CO2 and 74∼90% as 14CH4 and other hydrocarbons, compared to about 95% as 14CO2 and 5% as 14CH4 and other hydrocarbons in BWR station gaseous emissions. Knowles reported that although the exact nature of these organic compounds was not identified, most of the carbon-14 was present as forms of organic species in a PWR primary coolant. Praudic measured the contents of the total organic and inorganic carbon-14 in waste trench leachates of New York commercial LLW disposal site and found that 74 ∼ 98% of carbon-14 was organic. In 1991, Dayal and Kirby reported that carbon-14 identified in LLW trench leachates from the Maxi Fiats site were carbonate and bicarbonate as inorganic carbon-14 and citric acid and palmitic acid as organic carbon-14. Thus concentrated Boric acid waste solutions(CB) which has generated from domestic NPP were classified into organic and inorganic carbon-14 with wet oxidation method in order to grasping a existing ratio of organic carbon-14 from total one due to affecting an environment

  6. Compilation of carbon-14 data

    International Nuclear Information System (INIS)

    A review and critical analysis was made of the original sources of carbon-14 in the graphite moderator and reflector zones of the eight Hanford production reactors, the present physical and chemical state of the carbon-14, pathways (other than direct combustion) by which the carbon-14 could be released to the biosphere, and the maximum rate at which it might be released under circumstances which idealistically favor the release. Areas of uncertainty are noted and recommendations are made for obtaining additional data in three areas: (1) release rate of carbon-14 from irradiated graphite saturated with aerated water; (2) characterization of carbon-14 deposited outside the moderator and reflector zones; and (3) corrosion/release rate of carbon-14 from irradiated steel and aluminum alloys

  7. Organic Carbon Delivery to a High Arctic Watershed over the Late Holocene: Insights from Plant Biomarkers and Compound Specific δ13C and Δ14C Measurements

    Science.gov (United States)

    Schreiner, K. M.; Bianchi, T. S.; Eglinton, T. I.; Allison, M. A.

    2012-12-01

    The Colville River in Alaska is the largest river in North America which has a drainage basin that is exclusively underlain by permafrost, and as such provides a unique signal of historical changes in one of the world's most vulnerable areas to climate changes. Additionally, the Colville flows into Simpson's Lagoon, an area of the Alaskan Beaufort coast protected by a barrier island chain, lessening the impacts of Arctic storms and ice grounding on sediment mixing. Cores collected from the Colville river delta in August of 2010 were found to be composed of muddy, organic-rich, well-laminated sediments. The 2.5 to 3 meter length of each core spans about one to two thousand years of Holocene history, including the entire Anthropocene and much of the late Holocene. Two cores were sampled for this data set - one from close to the river mouth, and one from farther east in Simpson's Lagoon. Samples were taken every 2 cm for the entire length of both cores. In order to determine how the amount of terrestrial organic matter input changed over the Holocene, bulk analyses including percent organic carbon, percent nitrogen, and stable carbon isotopic analysis were performed, and biomarkers including lignin-phenols and fatty acids were measured. It was shown that lignin-phenol input is positively correlated with Alaskan North Slope temperature reconstructions. To determine whether the source of this increased terrestrial organic matter input was from fresh vegetation (for example, shrub encroachment onto tundra areas) or aged soil organic matter (potentially due to permafrost thawing and breakdown), selected samples were analyzed for compound-specific δ13C and Δ14C of fatty acids and lignin-phenols. These analyses show significant changes in carbon storage and in terrestrial carbon delivery to the Lagoon over time. These results represent the first fine-scale organic biomarker study in a high Arctic North American Lagoon, and have many implications for the future of carbon

  8. Carbon 14 dating method

    International Nuclear Information System (INIS)

    This document gives a first introduction to 14C dating as it is put into practice at the radiocarbon dating centre of Claude-Bernard university (Lyon-1 univ., Villeurbanne, France): general considerations and recalls of nuclear physics; the 14C dating method; the initial standard activity; the isotopic fractioning; the measurement of samples activity; the liquid-scintillation counters; the calibration and correction of 14C dates; the preparation of samples; the benzene synthesis; the current applications of the method. (J.S.)

  9. Carbon-14 in tree rings

    International Nuclear Information System (INIS)

    In order to investigate how reliably the carbon 14 content of tree rings reflects that of atmospheric carbon dioxide, two types of determinations were carried out: (1) carbon 14 determinations in annual rings from the beginning of this century until 1974 and (2) carbon 14 determinations in synchronous wood from the North American bristlecone pine and from European oak trees, dendrochronologically dated to have grown in the third and fourth century B.C. The first series of measurements showed that bomb-produced radiocarbon was incorporated in wood at a time when it was converted from sapwood to heartwood, whenever radiocarbon from bomb testing was present in the atmosphere. The second series showed that wood more than 2000 years old and grown on two different continents at different altitudes had, within the limits of experimental error, the same radiocarbon content. This work and other experimental evidence, obtained in part by other laboratories, show that tree rings reflect the average radiocarbon content of global atmospheric carbon dioxide accurately within several parts per mil. In rare cases, deviations of up to 10 parts per thousand may be possible. This means that a typical single radiocarbon date for wood or charcoal possesses an intrinsic uncertainty (viz., an estimated ''one-sigma error'' in addition to all the other errors) of the order of +-50 years. This intrinsic uncertainty is independent of the absolute age of the sample. More accurate dates can, in principle, be obtained by the so-called method of ''wiggle matching.''

  10. Carbon-14: Some evidence of migration and experiments on immobilization

    International Nuclear Information System (INIS)

    Carbon-14 that is produced in nuclear reactors by reactions on C, N and O is one of the most biologically dangerous nuclides that are subject to global dispersion (H-3, 85-Kr, 129-I). It is assumed that about 20-30% of C-14 is released to atmosphere from NPPs and 80-70% remains in the fuel and will be released during reprocessing. Atmospheric dispersion of C-14 in the form of carbon dioxide cannot go without consequence for the environment, particularly for the vegetation. This influence of the carbon-14 release from a radio-chemical facility in Russia on the nearby forest is illustrated in the first part of the report by data on C-14 concentration in the barks of trees, analyzed year by year and showing yearly variation of C-14 releases. The second part of the report deals with the study of stability of portland-cement compounds and Ca, Ba and Sr carbonates to the leaching processes. Leaching tests were done on specially prepared samples of compounds, containing various (from 30% to 70%) concentrations of Ca, Sr or Ba carbonates, tagged by C-14. Distilled water was used as leaching agent. Leaching was conducted for 46 hours and C-14 concentrations and pH of resulting waters were monitored. Differential leaching rates and leaching coefficients were analyzed and general compound behavior and its dynamics has been observed

  11. Soil metabolic transformations of carbon-14-myo-inositol, carbon-14-phytic acid and carbon-14-iron(III) phytate

    International Nuclear Information System (INIS)

    Uniformly labelled 14C-phytic acid and 14C-iron(III) phytate were synthesized from uniformly labelled 14C-myo-inositol. The three compounds were incubated in an Andosol sandy loam at 70% field capacity and 36.50C for a 12-day period. Myo-inositol, phytic acid and iron(III) phytate underwent a 61.0, 1.9 and 0% microbial oxidation respectively to CO2 during the incubation period. The rate of fixation of 14C-phytic acid was illustrated by its rapid decline in metabolism in the 12-day period. The metabolism rate of phytic was considerably reduced by the presumed formation of iron(III) and aluminium phytate. The metabolism rate of myo-inositol was reduced nine-fold after an initial rapid metabolism during the first day of incubation. The following mechanisms were observed in the soil metabolism of myo-inositol: (1) soil mineral-inositol carbon adsorption, (2) humic acid-inositol carbon adsorption, (3) the phosphorylation of myo-inositol, and (4) the epimerization of myo-inositol to chiro-inositol. The formation of (1) and (2) was found to be highly dependent upon microbial activity. Interactions (1), (2) and (3)are considered as possible mechanisms for the inhibition of the microbial oxidation of myo-inositol. The inhibition of myo-inositol oxidation via adsorption or phosphorylation is considered to be due to the chemical blockage of the stereo-specific microbial oxidative attack on the axial hydroxyl group. (author)

  12. Biomass carbon-14 ratio measured by accelerator mass spectrometry

    International Nuclear Information System (INIS)

    Measurement methods of a biomass carbon ratio in biomass products based on 14C-radiocarbon concentration have been reviewed. Determination of the biomass carbon ratio in biomass products is important to secure the reliance in the commercial market, because the 'biomass products' could contain products from petroleum. The biomass carbon ratio can be determined from percent Modern Carbon (pMC) using ASTM D6866 methods. The pMC value is calculated from the comparison between the 14C in sample and 14C in reference material. The 14C concentration in chemical products can be measured by liquid scintillation counter (LSC) and accelerator mass spectrometry (AMS). LSC can be applicable to determine the biomass carbon ratio for liquid samples such as gasoline with bioethanol (E5 or E10). On the other hand, AMS can be used to determine the biomass carbon ratio for almost all kinds of organic and inorganic compounds such as starch, cellulose, ethanol, gasoline, or polymer composite with inorganic fillers. AMS can accept the gaseous and solid samples. The graphite derived from samples included in solid phase is measured by AMS. The biomass carbon of samples derived from wood were higher than 100% due to the effect of atomic bomb test in the atmosphere around 1950 which caused the artificial 14C injection. Exact calculation methods of the biomass carbon ratio from pMC will be required for the international standard (ISO standard). (author)

  13. Carbon-14 Bomb-Pulse Dating

    Energy Technology Data Exchange (ETDEWEB)

    Buchholz, B A

    2007-12-16

    Atmospheric testing of nuclear weapons during the 1950s and early 1960s doubled the concentration of carbon-14 atmosphere and created a pulse that labeled everything alive in the past 50 years as carbon moved up the food chain. The variation in carbon-14 concentration in time is well-documented and can be used to chronologically date all biological materials since the mid-1950s.

  14. Carbon-14 dating with the 14UD accelerator

    International Nuclear Information System (INIS)

    A carbon-14 accelerator mass spectroscopy system is now in routine operation on the 14UD accelerator. It offers a modest precision of ∼ 3% for samples that are >10% modern. Its performances and some of recent applications are briefly discussed

  15. The carbon 14 and environment; Le carbone 14 et l'environnement

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-07-01

    This article resume the history and the properties of the carbon 14 ({sup 14}C). We also find the different origins and the produced quantities. The carbon transfers in environment are explained and so the {sup 14}C. The biological effects and the sanitary aspects are clarified. The measurements of carbon 14 are given as well its application through the dating. The waste management is tackled. (N.C.)

  16. Heterocyclic compounds as carbonic anhydrase inhibitor.

    Science.gov (United States)

    Husain, Asif; Madhesia, Diwakar

    2012-12-01

    The carbonic anhydrases (CAs, EC 4.2.1.1) constitute interesting targets for the design of pharmacological agents useful in the treatment or prevention of a variety of disorders such as, glaucoma, acid-base disequilibria, epilepsy, and other neuromuscular diseases, altitude sickness, edema, and obesity. A quite new and unexpected application of the CA inhibitors (CAIs) is with regard to their potential use in the management (imaging and treatment) of hypoxic tumors. A series of sulfonamides, including some clinically used derivatives like acetazolamide, methazolamide, ethoxzolamide, dichlorophenamide, dorzolamide, brinzolamide, benzolamide, and sulpiride, or indisulam, a compound in clinical development as antitumor drug, as well as the sulfamate antiepileptic drug topiramate have been reported to inhibit various human carbonic anhydrase isozyme. Various heterocyclic sulfonamides have been reported in this review with their potency to inhibit different carbonic anhydrases isozymes. PMID:21981003

  17. Carbon 14 and tritium radioactivity of alcohols

    International Nuclear Information System (INIS)

    The method of measuring carbon 14 radioactivity of alcohols has been perfected in order to establish the correct determination of synthetic alcohol added to fermentation alcohol. The specific carbon and tritium activity of alcohol of different origins have been determined for 1973 and 1974. The Suess effect and nuclear fall-out are observed

  18. MODIFYING V-14 RUBBER WITH CARBON FIBERS

    OpenAIRE

    Shadrinov N. V.; Nartakhova S. I.

    2016-01-01

    The influence of carbon fibers and modified carbon fibers on properties of industrially produced V-14 rubber is examined. The dependences of physical and mechanical properties, hardness, abrasion resistance and resistance in aggressive environment on few amount of filled fiber are established. Structural properties of reinforced elastomeric composites are studied by scanning electron microscopy. Elastomeric layer on the surface of modified carbon fiber, confirmed with high adhesion is identified

  19. Carbon-14 measurements in aquifers with methane

    International Nuclear Information System (INIS)

    A survey of various groundwater systems indicates that methane is a common trace constituent and occasionally a major carbon species in groundwaters. Thermocatalytic methane had delta13Csub(CH4)>-45 per mille and microbially produced or biogenic methane had delta13Csub(CH4)13C values for the inorganic carbon. Thermocatalytic methane had no apparent effect on the inorganic carbon. Because methanogenesis seriously affects the carbon isotope geochemistry of groundwaters, the correction of raw 14C ages of affected groundwaters must consider these effects. Conceptual models are developed which adjust the 14C activity of the groundwater for the effects of methanogenesis and for the dilution of carbon present during infiltration by simple dissolution of rock carbonate. These preliminary models are applied to groundwaters from the Alliston sand aquifer where methanogenesis has affected most samples. In this system, methanogenic bacteria using organic matter present in the aquifer matrix as substrate have added inorganic carbon to the groundwater which has initiated further carbonate rock dissolution. These processes have diluted the inorganic carbon 14C activity. The adjusted groundwater ages can be explained in terms of the complex hydrogeology of this aquifer, but also indicate that these conceptual models must be more rigorously tested to evaluate their appropriateness. (author)

  20. Analysis of lunar samples for carbon compounds.

    Science.gov (United States)

    Kvenvolden, K. A.

    1971-01-01

    Description of one approach to the analysis for carbon compounds in lunar materials from the Apollo 11 mission. The sequential scheme followed generally accepted organic geochemical practices, but was unusual in its application to a single sample. The procedures of the scheme were designed to minimize handling of the solids and extracts or hydrolysates. The solid lunar sample was retained in all steps of the sequential analysis in the vessel in which it was originally placed. Centrifugation was used to separate solid and liquid phases after extraction or refluxing. Liquids were recovered from solids by decantation.

  1. Carbon compounds in the atmosphere and their chemical reactions

    OpenAIRE

    Martišová, Petra

    2013-01-01

    The essay dissert on compounds of carbon in the atmosphere and its reaction. The most important are carbon dioxide, carbon monoxide and methane. Included among important compounds of carbon are volatile organic substances, polycyclic aromatic hydrocarbon and dioxin. Carbon dioxide and methane representing greenhouse gases have also indispensable meaning. As they, together with water vapour, nitrogen monoxide and other gases are causing the major part of greenhouse effect. Primarily because of...

  2. Cholestyramine-enhanced fecal elimination of carbon-14 in rats after administration of ammonium (/sup 14/C)perfluorooctanoate or potassium (/sup 14/C)perfluorooctanesulfonate

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, J.D.; Gibson, S.J.; Ober, R.E.

    1984-12-01

    After a single intravenous dose of ammonium (/sup 14/C)perfluorooctanoate (( /sup 14/C)PFO, 13.3 mg/kg) or of potassium (/sup 14/C)perfluorooctanesulfonate (( /sup 14/C)PFOS, 3.4 mg/kg) to rats, cholestyramine fed daily as a 4% mixture in feed was shown to increase the total carbon-14 eliminated via feces and to decrease liver concentration of carbon-14. Rats were fed cholestyramine in feed for 14 days after administration of (/sup 14/C)PFO and for 21 days after administration of (/sup 14/C)PFOS. Control rats were administered radiolabeled fluorochemical but were not treated with cholestyramine. Cholestyramine treatment increased mean cumulative carbon-14 elimination in feces by 9.8-fold for rats administered (/sup 14/C)PFO and by 9.5-fold for rats administered (/sup 14/C)PFOS. After (/sup 14/C)PFO, a mean of 4% of the dose of carbon-14 was in liver of cholestyramine-treated rats at 14 days versus 7.6% in control rats; after (/sup 14/C)PFOS, 11.3% of the dose was in liver at 21 days versus 40.3% in control rats. After administration of either radiolabeled compound, plasma and red blood cell carbon-14 concentrations, which were relatively lower than liver concentrations, were also significantly reduced by cholestyramine treatment.

  3. Cholestyramine-enhanced fecal elimination of carbon-14 in rats after administration of ammonium [14C]perfluorooctanoate or potassium [14C]perfluorooctanesulfonate

    International Nuclear Information System (INIS)

    After a single intravenous dose of ammonium [14C]perfluorooctanoate [( 14C]PFO, 13.3 mg/kg) or of potassium [14C]perfluorooctanesulfonate [( 14C]PFOS, 3.4 mg/kg) to rats, cholestyramine fed daily as a 4% mixture in feed was shown to increase the total carbon-14 eliminated via feces and to decrease liver concentration of carbon-14. Rats were fed cholestyramine in feed for 14 days after administration of [14C]PFO and for 21 days after administration of [14C]PFOS. Control rats were administered radiolabeled fluorochemical but were not treated with cholestyramine. Cholestyramine treatment increased mean cumulative carbon-14 elimination in feces by 9.8-fold for rats administered [14C]PFO and by 9.5-fold for rats administered [14C]PFOS. After [14C]PFO, a mean of 4% of the dose of carbon-14 was in liver of cholestyramine-treated rats at 14 days versus 7.6% in control rats; after [14C]PFOS, 11.3% of the dose was in liver at 21 days versus 40.3% in control rats. After administration of either radiolabeled compound, plasma and red blood cell carbon-14 concentrations, which were relatively lower than liver concentrations, were also significantly reduced by cholestyramine treatment

  4. Evaluation of carbon-14 life cycle in reactors VVER-1000

    International Nuclear Information System (INIS)

    This work is aimed at the evaluation of carbon-14 life cycle in light water reactors VVER-1000. Carbon-14 is generated as a side product in different systems of nuclear reactors and has been an issue not only in radioactive waste management but mainly in release into the environment in the form of gaseous effluents. The principal sources of this radionuclide are in primary cooling water and fuel. Considerable amount of C-14 is generated by neutron reactions with oxygen 17O and nitrogen 14N present in water coolant and fuel. The reaction likelihood and consequently volume of generated radioisotope depends on several factors, especially on the effective cross-section, concentrations of parent elements and conditions of power plant operating strategies. Due to its long half-life and high capability of integration into the environment and thus into the living species, it is very important to monitor the movement of carbon-14 in all systems of nuclear power plant and to manage its release out of NPP. The dominant forms of radioactive carbon-14 are the hydrocarbons owing to the combinations with hydrogen used for absorption of radiolytic oxygen. These organic compounds, such as formaldehyde, methyl alcohol, ethyl alcohol and formic acid can be mostly retained on ion exchange resins used in the system for purifying primary cooling water. The gaseous carbon compounds (CH4 and CO2) are released into the atmosphere via the ventilation systems of NPP. Based on the information and data obtained from different sources, it has been designed a balance model of possible carbon-14 pathways throughout the whole NPP. This model includes also mass balance model equations for each important node in system and available sampling points which will be the background for further calculations. This document is specifically not to intended to describe the best monitoring program attributes or technologies but rather to provide evaluation of obtained data and find the optimal way to upgrade

  5. Biokinetics and dosimetry of radioactively labelled organic C-14 compounds

    International Nuclear Information System (INIS)

    The report starts with summarising research work and the resulting scientific information in connection with the dosimetry of C-14 labelled organic compounds. Biokinetic models are developed for compounds such as benzene, phenol, aniline, nitrobenzene, and a selection of pharmaceuticals, in order to show the radioactivity distribution after administration of the C-14 labelled substances. Based on the those models, dose coefficients and excretion rates are derived. The following synoptic view of the available data library leads on to a discussion of various aspects, as eg. the question of whether and how monitoring for detection of incorporation of C-14 administered with labelled organic compounds is possible. None of the questions and aspects arising in connection with this subject can be adequately dealt with in the present document, but concepts and methods are presented which permit an interpretation of radioactivity excretion data measured after incorporation of C-14 labelled organic substances. (orig./CB)

  6. Laser ablation of molecular carbon nitride compounds

    International Nuclear Information System (INIS)

    We present a method for the preparation of thin films on sapphire substrates of the carbon nitride precursors dicyandiamide (C2N4H4), melamine (C3N6H6), and melem (C6N10H6), using the femtosecond-pulsed laser deposition technique (femto-PLD) at different temperatures. The depositions were carried out under high vacuum with a femtosecond-pulsed laser. The focused laser beam is scanned on the surface of a rotating target consisting of the pelletized compounds. The resulting polycrystalline, opaque films were characterized by X-ray powder diffraction, infrared, Raman, and X-ray photoelectron spectroscopy, photoluminescence, SEM, and MALDI-TOF mass spectrometry measurements. The crystal structures and optical/spectroscopic results of the obtained rough films largely match those of the bulk materials

  7. Laser ablation of molecular carbon nitride compounds

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, D., E-mail: d.fischer@fkf.mpg.de [Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart (Germany); Schwinghammer, K. [Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart (Germany); Department of Chemistry, University of Munich, LMU, Butenandtstr. 5-13, 81377 Munich (Germany); Nanosystems Initiative Munich (NIM) and Center for Nanoscience (CeNS), 80799 Munich (Germany); Sondermann, C. [Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart (Germany); Department of Chemistry, University of Munich, LMU, Butenandtstr. 5-13, 81377 Munich (Germany); Lau, V.W.; Mannhart, J. [Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart (Germany); Lotsch, B.V. [Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart (Germany); Department of Chemistry, University of Munich, LMU, Butenandtstr. 5-13, 81377 Munich (Germany); Nanosystems Initiative Munich (NIM) and Center for Nanoscience (CeNS), 80799 Munich (Germany)

    2015-09-15

    We present a method for the preparation of thin films on sapphire substrates of the carbon nitride precursors dicyandiamide (C{sub 2}N{sub 4}H{sub 4}), melamine (C{sub 3}N{sub 6}H{sub 6}), and melem (C{sub 6}N{sub 10}H{sub 6}), using the femtosecond-pulsed laser deposition technique (femto-PLD) at different temperatures. The depositions were carried out under high vacuum with a femtosecond-pulsed laser. The focused laser beam is scanned on the surface of a rotating target consisting of the pelletized compounds. The resulting polycrystalline, opaque films were characterized by X-ray powder diffraction, infrared, Raman, and X-ray photoelectron spectroscopy, photoluminescence, SEM, and MALDI-TOF mass spectrometry measurements. The crystal structures and optical/spectroscopic results of the obtained rough films largely match those of the bulk materials.

  8. Synthesis of carbon-14 labeled doxylamine succinate

    International Nuclear Information System (INIS)

    Doxylamine succinate, N,N-dimethyl-2-[1-phenyl-1-(2-pyridinyl)-ethoxy]ethanamine succinate is an antihistamine used primarily as a sedative. Carbon-14 labeled doxylamine succinate, required for toxicological studies, was synthesized in two steps starting from 2-benzoyl pyridine. (author)

  9. Carbon-Based Compounds and Exobiology

    Science.gov (United States)

    Kerridge, John; DesMarais, David; Khanna, R. K.; Mancinelli, Rocco; McDonald, Gene; diBrozollo, Fillipo Radicati; Wdowiak, Tom

    1996-01-01

    The Committee for Planetary and Lunar Explorations (COMPLEX) posed questions related to exobiological exploration of Mars and the possibility of a population of carbonaceous materials in cometary nuclei to be addressed by future space missions. The scientific objectives for such missions are translated into a series of measurements and/or observations to be performed by Martian landers. These are: (1) A detailed mineralogical, chemical, and textural assessment of rock diversity at a landing site; (2) Chemical characterization of the materials at a local site; (3) Abundance of Hydrogen at any accessible sites; (4) Identification of specific minerals that would be diagnostic of aqueous processes; (5) Textual examination of lithologies thought to be formed by aqueous activity; (6) Search for minerals that might have been produced as a result of biological processes; (7) Mapping the distribution, in three dimensions, of the oxidant(s) identified on the Martian surface by the Viking mission; (8) Definition of the local chemical environment; (9) Determination of stable-isotopic ratios for the biogenic elements in surface mineral deposits; (10) Quantitative analysis of organic (non-carbonate) carbon; (11) Elemental and isotopic composition of bulk organic material; (12) Search for specific organic compounds that would yield information about synthetic mechanisms, in the case of prebiotic evolution, and about possible bio-markers, in the case of extinct or extant life; (13) and Coring, sampling, and detection of entrained gases and cosmic-ray induced reaction products at the polar ice cap. A discussion of measurements and/or observations required for cometary landers is included as well.

  10. Volatile organic compound emissions in relation to plant carbon fixation and the terrestrial carbon budget

    OpenAIRE

    Kesselmeier, J.; P. Ciccioli; Kuhn, U.; Stefani, P.; Biesenthal, T.; Rottenberger, S.; Wolf, A.; Vitullo, M.; R. Valentini; Nobre, A.; Kabat, P.; Andreae, M.O.

    2002-01-01

    A substantial amount of carbon is emitted by terrestrial vegetation as biogenic volatile organic compounds (VOC), which contributes to the oxidative capacity of the atmosphere, to particle production and to the carbon cycle. With regard to the carbon budget of the terrestrial biosphere, a release of these carbon compounds is regarded as a loss of photosynthetically fixed carbon. The significance of this loss for the regional and global carbon cycles is controversial. We estimate the amount of...

  11. Concentration of carbon-14 in plants

    International Nuclear Information System (INIS)

    The carbon-14 survey program initiated 1960 to gather data on current levels of carbon-14 in environments. Plants essential oil and fermented alcohol were selected as sample materials. The carbon contained in these materials is fixed from atmospheric carbon dioxide by anabolism, so they well reflect the variation of carbon-14 in biosphere. Thymol; Thymol was obtained from the essential oil of Orthodon Japonicium Benth which was cultivated and harvested every year in the experimental field of NIRS and Chiba University. The methylation was carried out to eliminate the strong quenching action of the phenolic group of thymol. Eighteen grams of thymol methyl ether was used as liquid scintillator by adding 0.4% PPO and 0.01% POPOP. Menthol; Menthol was obtained from Mentha arvensis L which was cultivated in the east part of Hokkaido and prepared by Kitami Factory of Federation of Agricultural Cooperative Society of Hokkaido. The chemical conversion of menthol to p-cymene was carried out and used as liquid scintillator as same as above sample. Lemongrass oil; Lemongrass oil was obtained from Cymbopogon citratus Stapf which was cultivated in Izu Experimental Station of Medicinal Plants, National Institute of Hygienic Science located Minami-Izu, Shizuoka Pref. The p-cymene derived from Lemongrass oil was used as liquid scintillator. Alcohol; All sample of fermented alcohol were obtained from the Alcohol Factories of Ministry of Trade and Industry. Raw materials of alcohol were sweet potatos cultivated in several prefectures in Japan ''high test'' molasses and blackstrap molasses imported from several countries of Asia, South America and South Africa, crude alcohol imported from U.S.A., Argentina and Brazil. Mixed solvent of 10 ml sample alcohol and 10 ml toluene or p-xylene containing 0.8% PPO and 0.1% dimethyl POPOP was used as liquid scintillator. (author)

  12. The lichens, tritium and carbon 14 integrators

    International Nuclear Information System (INIS)

    The present report concerns a research for the tritium and for the carbon 14 in lichens in a spirit of bio-indication: the first results appear in Daillant and al (2004 ) and additional results were presented to the congress B.I.O.M.A.P. in Slovenia, organized collectively by the institute Josef Stefan from Ljubljana and the international atomic energy agency from Vienna (Daillant and al 2003). (N.C.)

  13. Carbon-14 in reactor plant water

    International Nuclear Information System (INIS)

    The method for the analysis of 14C in reactor plant water and various waste streams previously used at the Idaho National Engineering Laboratory has been shown to be ineffective for samples which contain organic compounds. The previous method consisted of acidification and refluxing of the sample, precipitation of the liberated CO2, and subsequent analysis by the liquid scintillation method. The method was simple but it did not convert all compounds containing 14C in the sample to CO2. The new method, while it is based on the previous method, has been improved by employing a strong oxidant, potassium persulfate and silver nitrate, for more complete oxidation of the organics to CO2. The new method yields 14C values that have typically been one to two orders of magnitude higher than the values obtained using the former method. This indicates that most of the 14C present in the current reactor water samples being analyzed is associated with trace amounts of organics

  14. LDEO Carbon 14 Data from Selected Sea floor Cores

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Carbon-14 data in this file were compiled by W.F. Ruddiman and staff at the Lamont-Doherty Earth Observatory of Columbia University. Data include 974 carbon-14...

  15. A gaseous measurement system for carbon-14 dioxide and carbon-14 methane: An analytical methodology to be applied in the evaluation of the carbon-14 dioxide and carbon-14 methane produced via microbial activity in volcanic tuff

    International Nuclear Information System (INIS)

    The objectives of this study were to develop a gaseous measurement system for the carbon-14 dioxide and carbon-14 methane produced via microbial activity or geochemical action on leachate in tuff; to determine the trapping efficiency of the system for carbon-14 dioxide; to determine the trapping efficiency of the system for carbon-14 methane; to apply the experimentally determined factors regarding the system's trapping efficiency for carbon-14 dioxide and carbon-14 methane to a trapping algorithm to determine the activity of the carbon-14 dioxide and carbon-14 methane in a mixed sample; to determine the minimum detectable activity of the measurement process in picocuries per liter; and to determine the lower limit or detection of the measurement process in counts per minute

  16. Hydrogenated 5-carbon compound and method of making

    Science.gov (United States)

    Elliott, Douglas C.; Frye, John G.

    1999-01-01

    The present invention is based upon the surprising discovery that a 5-carbon compound selected from the group of 4-oxopentanoic acid, at least one lactone of 4-oxopentanoic acid, and combinations thereof, may be hydrogenated with a bimetallic catalyst of a noble metal in combination with a second metal and preserve the pendant methyl group. It was further unexpectedly discovered that the same conditions of bimetallic catalyst in the presence of hydrogen are useful for catalyzing the different intermediate reactions for example angelicalactone to gamma-valerolactone and gamma-valerolactone to 1,4-pentanediol. Finally, it was surprising that levulinic acid could be converted to 2-methyltetrahydrofuran with heating in the presence of the bimetallic catalyst and hydrogen in a single process vessel. The method of the present invention unexpectedly produced a fuel or fuel component having 2-methyltetrahydrofuran either in a yield greater than 4.5 mol % or in combination with alcohols.

  17. Hydrogenated 5-carbon compound and method of making

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, D.C.; Frye, J.G.

    1999-03-16

    The present invention is based upon the surprising discovery that a 5-carbon compound selected from the group of 4-oxopentanoic acid, at least one lactone of 4-oxopentanoic acid, and combinations thereof, may be hydrogenated with a bimetallic catalyst of a noble metal in combination with a second metal and preserve the pendant methyl group. It was further unexpectedly discovered that the same conditions of bimetallic catalyst in the presence of hydrogen are useful for catalyzing the different intermediate reactions, for example, angelicalactone to gamma-valerolactone and gamma-valerolactone to 1,4-pentanediol. Finally, it was surprising that levulinic acid could be converted to 2-methyltetrahydrofuran with heating in the presence of the bimetallic catalyst and hydrogen in a single process vessel. The method of the present invention unexpectedly produced a fuel or fuel component having 2-methyltetrahydrofuran either in a yield greater than 4.5 mol % or in combination with alcohols. 8 figs.

  18. Carbon-14 measurement using carbon dioxide absorption method - Our experience

    International Nuclear Information System (INIS)

    Carbon-C14 measurement using absorption technique consists of direct absorption of sample carbon dioxide into an absorber - scintillator mixture. This technique is a simple, fast, less expensive and less hazardous technique compared to benzene synthesis or any other technique. This techniques enable us in preparing six/seven samples in a day while benzene synthesis technique takes two days for the preparation of one sample. It is useful for radiocarbon age up to about 38,000 a BP (∼1 pMC), which is adequate for most of the hydrological investigations. All the total dissolved inorganic carbon (TDIC) is precipitated as barium carbonate from the ∼60 to 70 liters of water at the site. In the laboratory, it is reacted with orthophosphoric acid to give carbon dioxide (CO2). This carbon dioxide is transferred into 0.5 L capacity cylinder. The reaction and collection of gas is done under vacuum using a glass vacuum line. Carbon dioxide is directly absorbed in 11.5 ml of carbasorb + 11 ml of Permaflour V (commercially not available) or its equivalent scintillator in the specially made absorption apparatus. Since, absorption process is exothermic, temperature of the medium is maintained at about 220 deg. C, it results in the absorption of ∼7 m moles of carbon dioxide per mL of cabasorb. As reaction progresses, bubbles can be seen rising slowly. The end point is marked by rapid rise in the solution level. Carbon dioxide obtained from oxalic acid (Standard) and background carbon dioxide are also absorbed in the same quantity of absorber and scintillator mixture. Samples, standard and background are transferred in 22 mL teflon vials and counted in low level liquid scintillation counter (LKB Wallac 1220 Quantulus) for 1000 minutes. The counting efficiency at best factor of merit (AON/ON/√B) is ∼60 % where AON is normalized net count rate of standard and B is the background count rate. The mean count rate of last fifteen background samples is 0.64 ± .0005 cpm with an

  19. New effective chemically synthesized anti-smallpox compound NIOCH-14.

    Science.gov (United States)

    Mazurkov, Oleg Yu; Kabanov, Alexey S; Shishkina, Larisa N; Sergeev, Alexander A; Skarnovich, Maksim O; Bormotov, Nikolay I; Skarnovich, Maria A; Ovchinnikova, Alena S; Titova, Ksenya A; Galahova, Darya O; Bulychev, Leonid E; Sergeev, Artemiy A; Taranov, Oleg S; Selivanov, Boris A; Tikhonov, Alexey Ya; Zavjalov, Evgenii L; Agafonov, Alexander P; Sergeev, Alexander N

    2016-05-01

    Antiviral activity of the new chemically synthesized compound NIOCH-14 (a derivative of tricyclodicarboxylic acid) in comparison with ST-246 (the condensed derivative of pyrroledione) was observed in experiments in vitro and in vivo using orthopoxviruses including highly pathogenic ones. After oral administration of NIOCH-14 to outbred ICR mice infected intranasally with 100 % lethal dose of ectromelia virus, it was shown that 50 % effective doses of NIOCH-14 and ST-246 did not significantly differ. The 'therapeutic window' varied from 1 day before infection to 6 days post-infection (p.i.) to achieve 100-60 % survival rate. The administration of NIOCH-14 and ST-246 to mice resulted in a significant reduction of ectromelia virus titres in organs examined as compared with the control and also reduced pathological changes in the lungs 6 days p.i. Oral administration of NIOCH-14 and ST-246 to ICR mice and marmots challenged with monkeypox virus as compared with the control resulted in a significant reduction of virus production in the lungs and the proportion of infected mice 7 days p.i. as well as the absence of disease in marmots. Significantly lower proportions of infected mice and virus production levels in the lungs as compared with the control were demonstrated in experiments after oral administration of NIOCH-14 and ST-246 to ICR mice and immunodeficient SCID mice challenged with variola virus 3 and 4 days p.i., respectively. The results obtained suggest good prospects for further study of the chemical compound NIOCH-14 to create a new smallpox drug on its basis. PMID:26861777

  20. 14C in fractions of dissolved organic carbon in ground water

    International Nuclear Information System (INIS)

    Here we report carbon isotope ratios of fractions of natural organic compounds in ground waters isolated from the Stripa mine (Sweden) and the Milk River aquifer (Alberta, Canada). High-molecular-weight and low-molecular-weight fractions of the organic carbon were characterized and these, along with dissolved inorganic carbon, were analysed for δ13C and 14C. The 14C results suggest that the dissolved organic carbon originates from a combination of soil organic matter and kerogen in the aquifer matrix. The high-molecular-weight fractions show a predominant soil origin, whereas the low-molecular-weight fractions are often strongly influenced by kerogen. (author)

  1. Synthesis of a polycyclic aromatic hydrocarbon marked with carbon-14: (b, d e f) dibenzo-chrysene 14C-7,14

    International Nuclear Information System (INIS)

    (b, d e f) dibenzo-chrysene C-7,14 has been synthesized from radioactive carbon dioxide and the organic magnesium compound derived from 1,5 dibromo naphthalene. The product has been purified by a very precise series of fractionated chromatographs on alumina having a chromatographic activity. This has necessitated the development of a special technique. (author)

  2. Carbon compound used in hydrogen storage

    International Nuclear Information System (INIS)

    In the present work it is studied the activated carbon of mineral origin for the sorption of hydrogen. The carbon decreased of particle size by means of the one alloyed mechanical. The time of mill was of 10 hours. The characterization one carries out by scanning electron microscopy and X-ray diffraction. The hydrogen sipped in the carbon material it was determined using the Thermal gravimetric method (TGA). The conditions of hydrogenation went at 10 atm of pressure and ambient temperature during 18 hours. They were also carried out absorption/desorption cycles of hydrogen in the same one system of thermal gravimetric analysis. The results showed percentages of sorption of 2% approximately in the cycles carried out in the system TGA and of 4.5% in weight of hydrogen at pressure of 10 atmospheres and ambient temperature during 18 hours. (Author)

  3. The bonds in the cluster compound CZr6I14

    International Nuclear Information System (INIS)

    The electronic properties of the cluster compound CZr6I14 are discussed on the basis of EHT results. In the model cluster CZr6I184-the calculated Zr-Zr distance in the metal octahedron is enlarged by encapsulation of the interstitial C as well as by the surrounding ligands. The interstitial bond is realized by the two bond orbitals a1g, t1u, and, additionally, by three t1u orbitals of the 5 p(I) band. The Zr-Zr bonds are week. The cluster CZr6T184- is held together by strong C-Zr and Zr-I bonds. (author)

  4. Organic carbon transformation in agricultural soils : radiocarbon analysis of organic matter fractions and biomarker compounds

    OpenAIRE

    Rethemeyer, Janet

    2004-01-01

    Radiocarbon analyses of physical and chemical soil organic matter fractions as well as of individual compounds provided information on the origin, transformation and stabilisation of organic carbon in agricultural soils. A contamination of the soil at the study site at Halle/Saale (Germany) with fossil, lignite-derived carbon was identified by high apparent 14C ages of the organic matter in the plough horizon of about 5000 years BP and a decrease in 14C age with increasing soil depth. The fos...

  5. The lichens, tritium and carbon 14 integrators; Les lichens, integrateurs de tritium et de carbone 14

    Energy Technology Data Exchange (ETDEWEB)

    Daillant, O

    2007-07-01

    The present report concerns a research for the tritium and for the carbon 14 in lichens in a spirit of bio-indication: the first results appear in Daillant and al (2004 ) and additional results were presented to the congress B.I.O.M.A.P. in Slovenia, organized collectively by the institute Josef Stefan from Ljubljana and the international atomic energy agency from Vienna (Daillant and al 2003). (N.C.)

  6. Light harvesting with non covalent carbon nanotube / porphyrin compounds.

    OpenAIRE

    Roquelet, Cyrielle; Langlois, Benjamin; Vialla, Fabien; Garrot, Damien; Lauret, Jean-Sébastien; Voisin, Christophe

    2013-01-01

    We present recent developments in the synthesis and in the functional study of non covalently bound porphyrin/carbon nanotube compounds. The issue of the chemical stability of non covalent compounds is tackled by means of micelle assisted chemistry. The non covalent functionalization allows to preserve the electronic integrity of the nanotubes that display bright NIR luminescence. In the same time, the coupling between the subunits is very strong and leads to e cient energy transfer and PL qu...

  7. Behavior of carbon-14 in the Tokai reprocessing plant

    International Nuclear Information System (INIS)

    Carbon-14 released from the nuclear facilities is an important radionuclide for the safety assessment, because it tends to accumulate in environment through food chain and has a significant impact to personal dose. Carbon-14 has been monitored routinely as one of the main gaseous radionuclides exhausted from the Tokai Reprocessing Plant (TRP) since October of 1991. Furthermore, behavior of carbon-14 in TRP has been investigated through the reprocessing operation and the literature survey. This report describes the result of investigation about the behavior of carbon-14 in TRP as followings. 1. Only a very small amount of carbon-14 in the fuel was liberated into the shear off-gas and most of it was liberated into the dissolver off-gas. Part of the carbon-14 was trapped at the caustic scrubber installed in the off-gas treatment process, and untrapped carbon-14 was released into the environment from the main stack. Amount of carbon-14 released from the main stack was about 4.1∼6.5 GBq every ton of uranium reprocessed. 2. Carbon-14 trapped at the caustic scrubbers installed in the dissolver off-gas and in the vessel off-gas treatment process is transferred to the low active waste vessel. Amount of carbon-14 transferred to the low active waste vessel was about 5.4∼9.6 GBq every ton of uranium reprocessed. 3. The total amount of carbon-14 input to TRP was summed up to about 11.9∼15.5 GBq every ton of uranium reprocessed considering the released amount from the main stack and the trapped amount in the off-gas treatment devices. The amount of nitrogen impurity in the initial fuel was calculated about 15∼22ppm of uranium metal based on the measured carbon-14. 4. The solution in the low active waste vessel is concentrated at the evaporator. Most of the carbon-14 in the solution was transferred into concentrated solution. 5. Total Vitrification Demonstration Facility (TVF) started to operate in 1994. Since then, carbon-14 has been measured in the second sub stack

  8. Integrating Carbon Nanotubes into Microfluidic Chip for Separating Biochemical Compounds

    OpenAIRE

    Chen, Miaoxiang Max; Mogensen, Klaus Bo; BØGGILD, Peter; Kutter, Jörg Peter

    2012-01-01

    We present a new type of device to separate biochemical compounds wherein carbon nanotubes (CNTs) are integrated as chromatographic stationary phase. The CNTs were directly grown on the bottom of microfluidic channels on Si/SiO2 substrates by chemical vapor deposition (CVD). Acetylene was used as carbon source and Ni was employed as catalyst. For electrokinetic separations, higher electrical field strength is usually required; therefore, the CNTs were constructed in pillar-array-form by patte...

  9. Carbon dioxide capture by means of cyclic organic nitrogen compounds

    OpenAIRE

    García Abuín, Alicia

    2012-01-01

    The research work included in present PhD Thesis involves the research studies to capture carbon dioxide using different cyclic nitrogen organic compounds (glucosamine (GA), chitosan (C), alkyl-pyrrolidones, pyrrolidine (PYR) and piperidine (PIP). This investigation is based on the study of three experimental systems. Each of them has characteristics potentially suitable to achieve the aim of this work, that is to say, to improve the carbon dioxide capture process, which is pre...

  10. Variation of bioactive compounds content of 14 oriental strawberry cultivars.

    Science.gov (United States)

    Kim, Sung Kyeom; Kim, Dong Sub; Kim, Dae Young; Chun, Changhoo

    2015-10-01

    Variation in bioactive compounds content was assessed in antioxidant rich June-bearing strawberry cultivars. Ascorbic acid, anthocyanin, and ellagic acid content were analyzed in ripe fruits of 14 cultivars. The bioactive content in strawberry fruit was found to vary significantly among cultivars and from year to year. The highest ascorbic acid content was found in 'Sugyeong'. The 'Red Pearl' and 'Sachinoka' had three to fourfold higher amounts of pelargonidin 3-glucoside than other cultivars. For cyanidin 3-glucoide and pelargonidin 3-rutinoside, two other characterized anthocyanins, 'Dahong' and 'Keumhyang' had the highest contents among all the tested cultivars. The ellagic acid content of 'Dahong' was generally all within the upper ranges. These results can be used for the validation of fruit antioxidant capacity and in addition, provide useful information for breeding programs looking to enhance the antioxidant capacity in strawberry fruit. PMID:25872444

  11. Carbon limitation reveals allocation priority to defense compounds in peppermint

    Science.gov (United States)

    Forkelova, Lenka; Unsicker, Sybille; Forkel, Matthias; Huang, Jianbei; Trumbore, Susan; Hartmann, Henrik

    2016-04-01

    Studies of carbon partitioning during insect or pathogen infestation reveal high carbon investment into induced chemical defenses to deter the biotic agent (Baldwin, 1998). However, little is known how carbon investment into chemical defenses changes under abiotic stress such as drought. Drought forces plants to close their stomata to prevent water loss through transpiration while decreasing the amount of assimilated carbon. Furthermore drought hampers carbohydrates translocation due to declining plant hydration and reduced phloem functioning (McDowell, 2011; Hartmann et al., 2013; Sevanto, 2014). Hence long lasting drought can force plants into carbon starvation. The aim of our study was to disentangle carbon allocation priorities between growth, maintenance metabolism, storage and production of defense compounds under carbon limiting conditions using peppermint as our model plant. Drought is not the only method how to manipulate plant carbon metabolism and photosynthetic yield. Exposing plants to reduced [CO2] air is a promising tool simulating drought induced carbon limitation without affecting phloem functioning and so carbohydrate translocation (Hartmann et al., 2015). We exposed peppermint plants to drought (50% of the control irrigation) and to low [CO2] (progressive decrease from 350 ppm to 20 ppm) to disentangle hydraulic failure from carbon starvation effects on carbon allocation. Drought was applied as a cross-treatment yielding four treatments: watered and high [CO2] (W+CO2), drought and high [CO2] (D+CO2), water and low [CO2] (W-CO2), drought and low [CO2] (D-CO2). We analyzed the most abundant terpenoid defense compounds (α-Pinene, sabinene, myrcene, limonene, menthone, menthol and pulegone) and used continuous 13CO2 labelling to trace allocation pattern of new and old assimilated carbon in the four carbon sinks (structural biomass, water soluble sugars, starch and terpenoid defense compounds) in young expanding leaf tissue. This leaf tissue grew

  12. Tracing carbon fixation in phytoplankton—compound specific and total

    NARCIS (Netherlands)

    Grosse, J.; Van Breugel, P.; Boschker, H.T.S.

    2015-01-01

    Measurement of total primary production using 13C incorporation is a widely established tool. However, these bulk measurements lack information about the fate of fixed carbon: the production of major cellular compounds (carbohydrates, amino acids, fatty acids, and DNA/RNA) is affected by for instanc

  13. Integrating Carbon Nanotubes into Microfluidic Chip for Separating Biochemical Compounds

    DEFF Research Database (Denmark)

    Chen, Miaoxiang Max; Mogensen, Klaus Bo; Bøggild, Peter;

    2012-01-01

    We present a new type of device to separate biochemical compounds wherein carbon nanotubes (CNTs) are integrated as chromatographic stationary phase. The CNTs were directly grown on the bottom of microfluidic channels on Si/SiO2 substrates by chemical vapor deposition (CVD). Acetylene was used as...

  14. The optimization of the estimation of carbon-14 in urine

    International Nuclear Information System (INIS)

    The urinalysis method for carbon-14 currently used by the bioassay laboratory of the Dosimetric Research Branch at CRNL has been tested and optimized for both sensitivity and efficiency. Urine is first treated with an enzyme that catalyses the hydrolysis of urea, the major carbon-containing component of urine; carbon dioxide is then liberated by the measured addition of excess acid and collected in 2-aminoethanol. The aminoethanol can be directly counted by the addition of a liquid scintillation cocktail. This method can be used to measure both the specific activity, (Bq/g-carbon) or the total activity of carbon-14 released from the urine sample

  15. Carbon isotope analysis of carbonaceous compounds in Puget Sound and Lake Washington

    International Nuclear Information System (INIS)

    A new method has been developed and tested for determining chronological profiles of organic pollutants. This method, Carbon Isotope Analysis (CIA), involves measurements of 12C, 13C and 14C in carbonaceous compounds found in layers of sediment. Lipids, total aliphatic hydrocarbons (TAHs) and polycyclic aromatic hydrocarbons (PAHs) are separated from kg quantities of sediment. Large Soxhlet extractors are used to remove the extractable organics, using ultra-pure benzene-methanol solution and having an extraction efficiency of about 86% for compounds with boiling points higher than n-tetradecane (n-C14). The basic steps in compound separation include freeze-drying, extraction, fractionation, column chromatography and evaporation. Isolating the TAH and PAH fractions is accomplished by eluting samples from Sephadex and alumina/silica-gel columns. The amount of each fraction recovered is determined by converting the hydrocarbons to carbon dioxide and measuring this gas manometrically. Variations in 12C and 13C abundances for carbonaceous compounds are primarily due to thermodynamic, photosynthetic and metabolic fractionation processes. Thus, the source of a particular organic compound can often be determined by measuring its 13C/12C ratio. Combining the information from both the 13C analysis and 14C analysis makes source identification more certain. In addition, this investigation reviews carbon isotopic data and carbon cycling and analyzes organic pollution in two limited ecosystems (Puget Sound and Lake Washington). Specifically, distinct carbonaceous species are analyzed for pollution in sediments of Lake Washington, Elliott Bay, Commencement Bay, central Puget Sound and northern Puget Sound near the Cherry Point oil refineries

  16. Analytical Validation of Accelerator Mass Spectrometry for Pharmaceutical Development: the Measurement of Carbon-14 Isotope Ratio.

    Energy Technology Data Exchange (ETDEWEB)

    Keck, B D; Ognibene, T; Vogel, J S

    2010-02-05

    Accelerator mass spectrometry (AMS) is an isotope based measurement technology that utilizes carbon-14 labeled compounds in the pharmaceutical development process to measure compounds at very low concentrations, empowers microdosing as an investigational tool, and extends the utility of {sup 14}C labeled compounds to dramatically lower levels. It is a form of isotope ratio mass spectrometry that can provide either measurements of total compound equivalents or, when coupled to separation technology such as chromatography, quantitation of specific compounds. The properties of AMS as a measurement technique are investigated here, and the parameters of method validation are shown. AMS, independent of any separation technique to which it may be coupled, is shown to be accurate, linear, precise, and robust. As the sensitivity and universality of AMS is constantly being explored and expanded, this work underpins many areas of pharmaceutical development including drug metabolism as well as absorption, distribution and excretion of pharmaceutical compounds as a fundamental step in drug development. The validation parameters for pharmaceutical analyses were examined for the accelerator mass spectrometry measurement of {sup 14}C/C ratio, independent of chemical separation procedures. The isotope ratio measurement was specific (owing to the {sup 14}C label), stable across samples storage conditions for at least one year, linear over 4 orders of magnitude with an analytical range from one tenth Modern to at least 2000 Modern (instrument specific). Further, accuracy was excellent between 1 and 3 percent while precision expressed as coefficient of variation is between 1 and 6% determined primarily by radiocarbon content and the time spent analyzing a sample. Sensitivity, expressed as LOD and LLOQ was 1 and 10 attomoles of carbon-14 (which can be expressed as compound equivalents) and for a typical small molecule labeled at 10% incorporated with {sup 14}C corresponds to 30 fg

  17. Experimental investigation of single carbon compounds under hydrothermal conditions

    Science.gov (United States)

    Seewald, Jeffrey S.; Zolotov, Mikhail Yu.; McCollom, Thomas

    2006-01-01

    The speciation of carbon in subseafloor hydrothermal systems has direct implications for the maintenance of life in present-day vent ecosystems and possibly the origin of life on early Earth. Carbon monoxide is of particular interest because it represents a key reactant during the abiotic synthesis of reduced carbon compounds via Fischer-Tropsch-type processes. Laboratory experiments were conducted to constrain reactions that regulate the speciation of aqueous single carbon species under hydrothermal conditions and determine kinetic parameters for the oxidation of CO according to the water water-gas shift reaction (CO 2 + H 2 = CO + H 2O). Aqueous fluids containing added CO 2, CO, HCOOH, NaHCO 3, NaHCOO, and H 2 were heated at 150, 200, and 300 °C and 350 bar in flexible-cell hydrothermal apparatus, and the abundances of carbon compounds was monitored as a function of time. Variations in fluid chemistry suggest that the reduction of CO 2 to CH 3OH under aqueous conditions occurs via a stepwise process that involves the formation of HCOOH, CO, and possibly CH 2O, as reaction intermediaries. Kinetic barriers that inhibit the reduction of CH 3OH to CH 4 allow the accumulation of reaction intermediaries in solution at high concentrations regulated by metastable thermodynamic equilibrium. Reaction of CO 2 to CO involves a two-step process in which CO 2 initially undergoes a reduction step to HCOOH which subsequently dehydrates to form CO. Both reactions proceed readily in either direction. A preexponential factor of 1.35 × 10 6 s -1 and an activation energy of 102 kJ/mol were retrieved from the experimental results for the oxidation of CO to CO 2. Reaction rates amongst single carbon compounds during the experiments suggest that ΣCO 2 (CO 2 + HCO 3- + CO 32-), CO, ΣHCOOH (HCOOH + HCOO -), and CH 3OH may reach states of redox-dependent metastable thermodynamic equilibrium in subseafloor and other hydrothermal systems. The abundance of CO under equilibrium conditions

  18. Increased root exudation of 14C-compounds by sorghum seedlings inoculated with nitrogen-fixing bacteria

    International Nuclear Information System (INIS)

    Organic components leaked from Sorghum bicolor seedlings ('root exudates') were examined by recovering 14C labelled compounds from root solutions of seedlings inoculated with Azospirillum brasilense, Azotobacter vinelandii or Klebsiella pneumoniae nif-. Up to 3.5% of the total 14C recovered from shoots, roots, and nutrient solutions was found in the root solutions. Inoculation with Azospirillum and Azotobacter increased the amounts of 14C and decreased the amounts of carbohydrates in the root solutions. When sucrose was added as a carbon source for the bacteria, the increase of 14C in the solutions did not occur. Quantities of 14C found in the root solutions were proportional to amounts of mineral nitrogen supplied to the plants. Bacterial growth also was proportional to nitrogen levels. When sorghum plants were grown in soil and labelled with 14CO2, about 15% of the total 14C recovered within 48 hours exposure was found in soil leachates. (orig.)

  19. Distribution of 14C-activity among the organic acids in the Satsuma mandarin fruits fed with 14C-compounds

    International Nuclear Information System (INIS)

    1. Twenty four hours after 14CO2 feeding to the leaves, malic acid had the highest level of total and specific radioactivity among the organic acids extracted from the juice vesicles, and citric acid had the second highest total activity. An unidentified acid compound had a relatively high activity. 2. Pyruvic acid-2-14C was fed as a substrate for acid formation to the one young fruit on a shoot, and NaH14CO3 was fed as a source of carbon-dioxide to the other young fruit through the pedicel. After three hours of pyruvic acid feeding, malic acid, citric acid and aspartic acid were the major labelled compounds in the vesicles. Then, a marked increase and redistribution of activity in acids took place with time, and the levels of total and specific activity in citric acid increased steadily. The sorts of labelled compounds into which activity was incorporated from NaH14CO3 were essentially similar to those in pyruvic acid-2-14C feeding. 3. These results seem to support the theory that the dark fixation of carbon-dioxide plays an important role in the synthesis of the organic acids in citrus fruit vesicles. (auth.)

  20. Molecular switches in carbon-rich organometallic compounds: Theoretical aspects

    Energy Technology Data Exchange (ETDEWEB)

    Costuas, Karine, E-mail: kcostuas@univ-rennes1.fr [Sciences chimiques de Rennes, UMR 6226 CNRS - Université de Rennes 1, Avenue du Général Leclerc F-35042 Rennes (France)

    2015-01-22

    Organometallic complexes associated with an appropriate choice of ancillary ligands reveal to have a wide range of physical properties leading to promising applications when incorporated in nano-size devices. The challenge is to design innovative multifunctional compounds based on redox active carbon-rich organometallics associated with spin carriers and/or photochromic units. A multidisciplinary approach in this area has proved to be efficient in a series a systems combining carbon-rich bridging ligands and redox metallic moieties. In this domain, the role of theoretical investigations based on quantum mechanics tools have a crucial role in rationalizing and in helping designing systems possessing target properties.

  1. Molecular switches in carbon-rich organometallic compounds: Theoretical aspects

    International Nuclear Information System (INIS)

    Organometallic complexes associated with an appropriate choice of ancillary ligands reveal to have a wide range of physical properties leading to promising applications when incorporated in nano-size devices. The challenge is to design innovative multifunctional compounds based on redox active carbon-rich organometallics associated with spin carriers and/or photochromic units. A multidisciplinary approach in this area has proved to be efficient in a series a systems combining carbon-rich bridging ligands and redox metallic moieties. In this domain, the role of theoretical investigations based on quantum mechanics tools have a crucial role in rationalizing and in helping designing systems possessing target properties

  2. Carbon-14 kinetic isotope effect in the decarbonylation of lactic acid [1-14C

    International Nuclear Information System (INIS)

    The carbon-14 kinetic isotope effect for the decarbonation of lactic acid[1-14C] in sulfuric acid has been measured in the temperature interval of 20-90 deg C. The experimental values of (k12C/k14C) are compared with the theoretical 14C kinetic isotope effect calculated assuming that one carbon-oxygen stretching vibration is lost in the rate-determining step. The discrepancy between experimentally observed temperature dependence of the 14C kinetic isotope effect and the theoretical one is explained by the possible side reactions wich change the apparent degrees of decarbonylation and isotopic composition of CH3CHOHCOOH[1-14C] used in experiments aiming at the determination of carbon-14 kinetic isotope effect in the decarbonylation process itself. (author) 6 refs.; 1 tab

  3. The preparation of glucose uniformly labelled with carbon-14

    International Nuclear Information System (INIS)

    The plant, (Zea mais, L) and culture conditions for an optimum production of glucose has been chosen. To achieve the labelling of glucose, photosynthesis and carboxylation are carried on, under an artificial atmosphere of 14CO2 produced from 14C-barium carbonate. Following photosynthesis the sugars are extracted, and then the extract purified by several methods. The purified glucose is finally, degraded and the specific radioactivity is determined in each of its carbon atoms. (Author) 37 refs

  4. The preparation of glucosa uniformly labelled with carbon-14

    International Nuclear Information System (INIS)

    The plant, (Zea mais, L) and culture conditions for an optimun production of glucose has been chosen. To achieve the labelling of glucose, photosynthesis and carboxilation are carried on under an artificial atmosphere of 14CO2 produced from 14C-barium carbonate. Following photosynthesis, the sugars are extracted and then the extract purified by several methods. The purified glucose is, finally, degraded and the specific radiactivity is determined in each of its carbon atoms. (author)

  5. Hydrodynamic aspects of carbon-14 groundwater dating

    International Nuclear Information System (INIS)

    The influence of man-made hydraulic disturbances on the 14C ages of groundwater from confined aquifers is examined, also taking into account 14C diffusion, which has an effect on 14C ages only if the hydrostatic pressure in the lower, confined aquifer is not more than 0.5m higher than that in the upper, unconfined aquifer. If the water head of the lower aquifer exceeds this value, the 14C ages of the confined groundwater are reliable. If the water head is lower, the 14C water ages rapidly approach values of a few thousand years, which no longer reflect the history of the groundwater regeneration. With regard to the palaeohydrogeological situation in Central Europe and the Central Sahara during the last 40,000 years, the 14C ages of Holocene groundwater, and the duration of the preceding hiatus of the groundwater regeneration during the last glacial period, can be determined reliably. 14C ages older than that are too small in many cases; thus, groundwater velocities derived from such data are too great. Recently operations were started to use the groundwater from confined aquifers associated with rates for lowering the water table at 0.1-0.5m/a that result in a rapid decrease in the 14C ages determined for these aquifers, delayed for one or two decades after the beginning of the withdrawal. The 3H level and the chemical content of the groundwater may also be changed after the same delay period. Changes of this kind can be used to estimate the hydraulic properties of the aquifer system. In conclusion, an interpretation of the 14C content of the groundwater from confined aquifers in terms of its age is only possible if the water head of the confined aquifer has not been lower than that of the upper aquifer for even a relatively short period. (author)

  6. Irreversible adsorption of phenolic compounds by activated carbons

    International Nuclear Information System (INIS)

    Studies were undertaken to determine the reasons why phenolic sorbates can be difficult to remove and recover from activated carbons. The chemical properties of the sorbate and the adsorbent surface, and the influences of changes in the adsorption and desorption conditions were investigated. Comparison of isotherms established after different contact times or at different temperatures indicated that phenolic compounds react on carbon surfaces. The reaction rate is a strong function of temperature. Regeneration of carbons by leaching with acetone recovered at least as much phenol as did regeneration with other solvents or with displacers. The physiochemical properties of adsorbents influences irreversible uptakes. Sorbates differed markedly in their tendencies to undergo irreversible adsorption. 64 refs., 47 figs., 32 tabs

  7. 14C in fractions of dissolved organic carbon in ground water

    International Nuclear Information System (INIS)

    Here we report carbon isotope ratios of fractions of natural organic compounds in ground waters isolated from the Stripa mine (Sweden) and the Milk River aquifer (Alberta, Canada). High-molecular-weight and low-molecular-weight fractions of the organic carbon were characterized and these, along with dissolved inorganic carbon, were analysed for δ13C and 14C. The 14C results suggest that the dissolved organic carbon originates from a combination of soil organic matter and kerogen in the aquifer matrix. The high-molecular-weight fractions show a predominant soil origin, whereas the low-molecular-weight fractions are often strongly influenced by kerogen. (author). 23 refs., 1 fig., 1 tab

  8. Synthesis of carbon-14 labeled Taxol (paclitaxel)

    International Nuclear Information System (INIS)

    Reductive cleavage of the C13 side chain of Taxol (1, paclitaxel) followed by regioselective silylation gave 7-triethylsilylbaccatin III (4). 3-O-Triethysilylation of 5 and subsequent reaction with benzoyl chloride-C7-14C gave azetidinone 7. Coupling of 4 and 7 followed by deprotection gave 1.26 g of Taxol-N3'-14C (11) having a specific activity of 26.5 mCi/mmol and a radiochemical purity of 95%. (author)

  9. Photoassisted carbon dioxide reduction and formation of twoand three-carbon compounds. [prebiological photosynthesis

    Science.gov (United States)

    Halmann, M.; Aurian-Blajeni, B.; Bloch, S.

    1981-01-01

    The photoassisted reduction of aqueous carbon dioxide in the presence of naturally occurring minerals is investigated as a possible abiotic precursor of photosynthesis. Aqueous carbon dioxide saturated suspensions or surfaces of the minerals nontronite, bentonite, anatase, wolframite, molybdenite, minium, cinnabar and hematite were irradiated with high-pressure mercury lamps or sunlight. Chemical analyses reveal the production of formic acid, formaldehyde, methanol and methane, and the two and three-carbon compounds glyoxal (CHOCHO) and malonaldehyde (CH2(CHO)2). It is suggested that such photosynthetic reactions with visible light in the presence of semiconducting minerals may provide models for prebiological carbon and nitrogen fixation in both oxidized and reduced atmospheres.

  10. Preferential site occupation in Y and La substituted Pr2Fe14B intermetallic compounds

    International Nuclear Information System (INIS)

    The crystal structure of Y and La substituted Pr2Fe14B intermetallic compounds has been determined by high resolution neutron time-of-flight powder diffraction. A model which takes into account the rare-earth site occupancies and the measured magnetic anisotropy in Pr2Fe14B and Nd2Fe14B indicates that the contribution of the 4f site anisotropy to the total axial anisotropy is larger than that of the 4g site in Nd2Fe14B compounds. In Pr2Fe14B compounds, however, the 4f and 4g site anisotropies are equal. (orig.)

  11. Determination of carbon-14 environmental samples by mixing 14CO2 with a liquid scintillator

    International Nuclear Information System (INIS)

    A method for the determination of Carbon-14 (14CO2) in environmental samples has been developed. The method use the direct absorption of the carbon dioxide into Carbosorb, followed with incorporation of the mixture (Carbosorb-CO2) to the liquid scintillator. The results obtained to apply this method and the benzene synthesis, usual in our laboratory, are discused and compared. The method of collection of atmospheric samples is also described. (Author)

  12. Determination of Carbon-14 in environmental samples by mixing 14CO2 with a liquid scintillator

    International Nuclear Information System (INIS)

    A method for the determination of Carbon-14 (14CO2) in environmental samples has been developed. The method use the direct absorption of the carbon dioxide into Carbosorb, followed with incorporation of the mixture (Carbosorb-CO2) to the liquid scintillator. The results obtained to apply this method and the benzene synthesis, usual in our laboratory, are discussed and compared. The method of collection of atmospheric samples is also described. (Author) 10 refs

  13. Influence of sulfur compounds on the terrestrial carbon cycle

    Science.gov (United States)

    Eliseev, A. V.

    2015-11-01

    Using the climate model developed at the A.M. Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences (IAP RAS CM), numerical experiments have been conducted in line with the Coupled Model Intercomparison Project Phase 5 (CMIP5), but scaling the anthropogenic emissions of sulfur compounds into the troposphere by ±25%. Two types of impacts of sulfur compounds on climate and the global carbon cycle are considered: climate impact (CI, associated with the influence of tropospheric sulfates on climate and, as a consequence, on the carbon cycle characteristics) and ecological impact (EI, associated with the influence of SO2 on the rate of photosynthesis of terrestrial plants). The climate impact was found to be generally more important than the ecological one. However, in a number of regions, the EI is comparable to CI, including in the southeast parts of North America and, especially, of Asia. The contribution of EI to the change in global characteristics of terrestrial ecosystems in the 20th century is likewise considerable. The CI is generally more sensitive to the uncertainty in anthropogenic emissions of sulfur compounds into the troposphere than the EI.

  14. Fate of 14C-labelled compounds in marine environment

    International Nuclear Information System (INIS)

    Model ecosystems have played an important role in predicting environmental behavior of agrochemicals. The microcosms used in these studies generally include soil units containing usual biotic components common for that ecosystem. In present studies, scope of two such ecosystems has been extended to study the fate of 14C-labelled pesticides in marine environment. 14C-labelled pesticides used in these studies were chlorpyrifos, DDT and HCH. Two systems were developed in laboratory simulating marine environment to study the fate of these pesticides. The first system was developed in an all glass aquarium tank with marine sediments, seawater, clams and algae and is referred to as marine ecosystem. The second system was developed to permit the total 14C-mass balance studies. It contained marine sediments under moist (60% water holding capacity) or flooded conditions and it is referred to as continuous flow system. Fate of 14C-DDT was studied in marine ecosystem while degradation of 14C-chlorpyrifos and 14C-HCH was studied in continuous flow system. 14C-DDT did not bioaccumulate in clams while at the end of 60 days 50% of the applied 14C-activity was present in sediment fraction of marine ecosystem. 14C-HCH degradation showed about 22-26% mineralization while 45-55% of the applied activity was recovered as organic volatiles. No significant bound residues were formed. 14C-chorpyrifos underwent considerable degradation in marine environment. TCP was the major degradation product. (author)

  15. Kirishites, a new type of natural high-carbon compounds

    Science.gov (United States)

    Marin, Yu. B.; Skublov, G. T.; Yushkin, N. P.

    2010-01-01

    On the right-hand bank of the Volkhov River, in the natural area of tektite-like glasses (Volkhovites), fragments of shungites and slags with bunches of hairlike dark brownish enclosures were found. The filament thickness ranged from 20 to 100 μm, and separate “hairlines” were 3 cm in length. The composition of shungites and “hairlines” was found to be identical, which allowed us to consider the latter as aposhungite carbon formations. The high-carbon hairline structures associated with volkhovites are called kirishites. Kirishites are a new type of high-carbon structures that formed simultaneously with volkhovites in the case of explosion-type delivery of carbon slag and shungite fragments to the daylight surface during Holocene explosive activity. Under sharply reductive conditions, the slags partially melted, the melts were segregated, and carbonaceous-silicate and carbonaceous-ferriferous glasses formed with subsequent decompression-explosive liberation of carbon-supersaturated structures, which were extruded from shungite and slag fragments in the form of a resinoid mass. The “hairlines” were found to be zonal in structure: the central axial zones are composed of high-nitrogen hydrocarbon compounds, and peripheral regions are essentially carbonaceous with a high content of organic-mineral compounds and numerous microanomalies of petrogenic, volatile, rare, and ore elements. Infrared spectroscopy identified in kirishites proteinlike compounds, diagnosed in absorption bands (in cm-1) 600-720 (Amid V), 1200-1300 (Amid III), 1480-1590 (Amid II), 1600-1700 (Amid I), 3000-3800 (vibrations in NH2 and II groups). Gas chromatography, with the possibility of differentiation of left- and right-handed forms, revealed a broad spectrum of amino acids in kirishites, with their total content found to be the absolutely highest record for natural bitumens, an order of magnitude higher than the largest amino acid concentrations ever revealed in fibrous high

  16. Selective Sorption of Dissolved Organic Carbon Compounds by Temperate Soils

    Energy Technology Data Exchange (ETDEWEB)

    Jagadamma, Sindhu [ORNL; Mayes, Melanie [ORNL; Phillips, Jana Randolph [ORNL

    2012-01-01

    Physico-chemical sorption of dissolved organic carbon (DOC) on soil minerals is one of the major processes of organic carbon (OC) stabilization in soils, especially in deeper layers. The attachment of C on soil solids is related to the reactivity of the soil minerals and the chemistry of the sorbate functional groups, but the sorption studies conducted without controlling microbial activity may overestimate the sorption potential of soil. This study was conducted to examine the sorptive characteristics of a diverse functional groups of simple OC compounds (D-glucose, L-alanine, oxalic acid, salicylic acid, and sinapyl alcohol) on temperate climate soil orders (Mollisols, Ultisols and Alfisols) with and without biological degradative processes. Equilibrium batch experiments were conducted using 0-100 mg C L-1 at a solid-solution ratio of 1:60 for 48 hrs and the sorption parameters were calculated by Langmuir model fitting. The amount of added compounds that remained in the solution phase was detected by high performance liquid chromatography (HPLC) and total organic C (TOC) analysis. Soil sterilization was performed by -irradiation technique and experiments were repeated to determine the contribution of microbial degradation to apparent sorption. Overall, Ultisols did not show a marked preference for apparent sorption of any of the model compounds, as indicated by a narrower range of maximum sorption capacity (Smax) of 173-527 mg kg soil-1 across compounds. Mollisols exhibited a strong preference for apparent sorption of oxalic acid (Smax of 5290 mg kg soil-1) and sinapyl alcohol (Smax of 2031 mg kg soil-1) over the other compounds. The propensity for sorption of oxalic acid is mainly attributed to the precipitation of insoluble Ca-oxalate due to the calcareous nature of most Mollisol subsoils and its preference for sinapyl alcohol could be linked to the polymerization of this lignin monomer on 2:2 mineral dominated soils. The reactivity of Alfisols to DOC was in

  17. Study of barytocalcite as a conditioning matrix for carbon 14: Comparison of several synthesis routes

    Energy Technology Data Exchange (ETDEWEB)

    Massoni, Nicolas, E-mail: nicolas.massoni@cea.fr; Rosen, Jeremy; Chartier, Myriam; Cozzika, Théodore

    2013-10-15

    Carbon-14 arising from the spent nuclear fuel reprocessing can disseminate into natural cycles and then its sequestration could be advantageous. In this study, we focus on the ceramic phase barytocalcite BaCa(CO{sub 3}){sub 2} (8.08 wt.% C) obtained from different synthesis routes. We show that several elaboration routes are possible but only two emerge ensuring a high reaction yield for a fast process. The first is a room temperature aqueous precipitation with nitrated precursors and the other is a double salt high temperature reaction with carbonated starting compounds, both of these precursors being compatible with the usual carbon-14 trapping process. The sensibility to experimental conditions of reference synthesis route and the reaction mechanisms are investigated and discussed.

  18. Reactions between sodium and various carbon bearing compounds

    International Nuclear Information System (INIS)

    The presence of carbon bearing materials in liquid sodium is undesirable because of their ability to carburise stainless steel components. It has been demonstrated for example that carbon taken up by stainless steels can affect their mechanical properties and that thinner sectioned material such as fuel cladding and the tubing of intermediate heat exchanger may be more sensitive to such effects. Generally speaking, there are a number of potential carbon sources in reactor systems. Some of the sources such as the graphite in neutron shield rods, boron carbide in control rods and carbide fuels are part of the reactor designs while others such as oil in mechanical pumps arid 'coupling-fluids' used to inspect plant components are associated with the respective operation arid inspection of the plant. In this paper it is intended to discuss in general terms the way these various compounds behave in liquid sodium and to assess what effect their presence will have on the materials of construction in fast reactor systems. The paper also reviews the chemistry of the environment in relation to the types of carburizing species which may exist in sodium systems

  19. Monitoring of carbon 14 in atmospheric carbon dioxide

    International Nuclear Information System (INIS)

    A purpose of this article is to present the first data of the atmospheric C-14 monitoring in CO2 form. In the Prague-Bulovka locality atmospheric CO2 have been continuously collected by absorption in 0.7 M NaOH solution. The samples were one month cumulated. Afterwards, the CO2 was extracted from the NaOH solution and benzene was synthesised. The benzene was measured by liquid scintillation counting (LSC). The monitoring results from January to July 2001 period are discussed and compared with the results from other countries. (authors)

  20. 14,15N beam from cyanide compounds

    International Nuclear Information System (INIS)

    We report here on the direct generation of a CN− ion beam for the production of a N ion beam to be used in nuclear astrophysics measurements. The procedure relies on the production of CN− ion beam with a SNICS source starting from several appropriate substrates containing CN− triple bond. Several of the investigated substrates showed a higher beam intensity with respect to the common N beam production from a cathode of BN plus graphite. Best results in terms of analyzed beam intensity were observed with K3Fe(CN)6 and KSCN cathodes. Use of the latter compound is particularly appealing because of the easy availability of mass-15 enriched molecule.

  1. Thermal Expansion Anomaly of Tb2Fe14Cr3 Compound

    Institute of Scientific and Technical Information of China (English)

    HAO Yan-Ming; HE Xiao-Hong; AN Li-Qun; Fu Bin

    2008-01-01

    We investigate the thermal expansion property of the Tb2Fe14Cr3 compound by means of x-ray diffraction.The result shows that the Tb2Fe14Cr3 compound has a hexagonal Th2Ni17-type structure.Negative thermal expansion is found in the Tb2Fe14Cr3 compound from 296 to 493K by x-ray dilatometry.The coefficient of the average thermal expansion is (a)=-2.82×10-5 K-1.In the temperature range 493-692K,the coefficient of the average thermal expansion is (a)=1.59×10-5 K-1.The physical mechanism of thermal expansion anomaly of the Tb2Fe14Cr3 compound is discussed according to the temperature dependence of magnetization measured by a superconducting quantum interference device.

  2. Carbon-14 geochemistry at the Savannah River Site

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, Kimberly A.; Kaplan, Daniel I.

    2013-05-10

    Carbon-14 is among the key radionuclides driving risk at the E-Area Low-Level Waste Disposal Facility on the Savannah River Site (SRS). Much of this calculated risk is believed to be the result of having to make conservative assumptions in risk calculations because of the lack of site-specific data. The original geochemical data package (Kaplan 2006) recommended that performance assessments and composite analyses for the SRS assume that {sup 14}C did not sorbed to sediments or cementitious materials, i.e., that C-14 K{sub d} value (solid:liquid concentration ratio) be set to 0 mL/g (Kaplan 2006). This recommendation was based primarily on the fact that no site-specific experimental work was available and the assumption that the interaction of anionic {sup 14}C as CO{sub 2}{sup 2-}) with similarly charged sediments or cementitious materials would be minimal. When used in reactive transport equations, the 0 mL/g Kd value results in {sup 14}C not interacting with the solid phase and moving quickly through the porous media at the same rate as water. The objective of this study was to quantify and understand how aqueous {sup 14}C, as dissolved carbonate, sorbs to and desorbs from SRS sediments and cementitious materials. Laboratory studies measuring the sorption of {sup 14}C, added as a carbonate, showed unequivocally that {sup 14}C-carbonate K{sub d} values were not equal to 0 mL/g for any of the solid phases tested, but they required several months to come to steady state. After six months of contact, the apparent K{sub d} values for a clayey sediment was 3,000 mL/g, for a sandy sediment was 10 mL/g, for a 36-year-old concrete was 30,000 mL/g, and for a reducing grout was 40 mL/g. Furthermore, it was demonstrated that (ad)sorption rates were appreciably faster than desorption rates, indicating that a kinetic sorption model, as opposed to the steady-state K{sub d} model, may be a more accurate description of the {sup 14}C-carbonate sorption process. A second study

  3. A potent IκB kinase-β inhibitor labeled with carbon-14 and deuterium.

    Science.gov (United States)

    Latli, Bachir; Eriksson, Magnus; Hrapchak, Matt; Busacca, Carl A; Senanayake, Chris H

    2016-06-30

    3-Amino-4-(1,1-difluoro-propyl)-6-(4-methanesulfonyl-piperidin-1-yl)-thieno[2,3-b]pyridine-2-carboxylic acid amide (1) is a potent IκB Kinase-β (IKK-β) inhibitor. The efficient preparations of this compound labeled with carbon-14 and deuterium are described. The carbon-14 synthesis was accomplished in six radiochemical steps in 25% overall yield. The key transformations were the modified Guareschi-Thorpe condensation of 2-cyano-(14) C-acetamide and a keto-ester followed by chlorination to 2,6-dichloropyridine derivative in one pot. The isolated dichloropyridine was then converted in three steps in one pot to [(14) C]-(1). The carbon-14 labeled (1) was isolated with a specific activity of 54.3 mCi/mmol and radiochemical purity of 99.8%. The deuterium labeled (1) was obtained in eight steps and in 57% overall chemical yield using 4-hydroxypiperidine-2,2,3,3,4,5,5,6,6-(2) H9 . The final three steps of this synthesis were run in one pot. PMID:27073120

  4. Dissolved Organic Carbon 14C in Southern Nevada Groundwater and Implications for Groundwater Travel Times

    Energy Technology Data Exchange (ETDEWEB)

    Hershey, Ronald L. [Nevada University, Reno, NV (United States). Desert Research Institute; Fereday, Wyall [Nevada University, Reno, NV (United States). Desert Research Institute; Thomas, James M [Nevada University, Reno, NV (United States). Desert Research Institute

    2016-08-01

    Dissolved inorganic carbon (DIC) carbon-14 (14C) ages must be corrected for complex chemical and physical reactions and processes that change the amount of 14C in groundwater as it flows from recharge to downgradient areas. Because of these reactions, DIC 14C can produce unrealistically old ages and long groundwater travel times that may, or may not, agree with travel times estimated by other methods. Dissolved organic carbon (DOC) 14C ages are often younger than DIC 14C ages because there are few chemical reactions or physical processes that change the amount of DOC 14C in groundwater. However, there are several issues that create uncertainty in DOC 14C groundwater ages including limited knowledge of the initial (A0) DOC 14C in groundwater recharge and potential changes in DOC composition as water moves through an aquifer. This study examines these issues by quantifying A0 DOC 14C in recharge areas of southern Nevada groundwater flow systems and by evaluating changes in DOC composition as water flows from recharge areas to downgradient areas. The effect of these processes on DOC 14C groundwater ages is evaluated and DOC and DIC 14C ages are then compared along several southern Nevada groundwater flow paths. Twenty-seven groundwater samples were collected from springs and wells in southern Nevada in upgradient, midgradient, and downgradient locations. DOC 14C for upgradient samples ranged from 96 to 120 percent modern carbon (pmc) with an average of 106 pmc, verifying modern DOC 14C ages in recharge areas, which decreases uncertainty in DOC 14C A0 values, groundwater ages, and travel times. The HPLC spectra of groundwater along a flow path in the Spring Mountains show the same general pattern indicating that the DOC compound composition does not change along this flow path

  5. Sorption of organic carbon compounds to the fine fraction of surface and Subsurface Soils

    Energy Technology Data Exchange (ETDEWEB)

    Jagadamma, Sindhu [ORNL; Mayes, Melanie [ORNL; Zinn, Yuri [Federal University of Lavras, Brazil; Gisladottir, Gudrun [University of Iceland; Ann, Russell [Iowa State University

    2014-01-01

    Dissolved organic carbon (DOC) transported from the soil surface is stabilized in deeper soil profiles by physicochemical sorption processes. However, it is unclear how different forms of organic carbon (OC) compounds common in soil organic matter interact with soil minerals in the surface (A) and subsurface (B) horizons. We added four compounds (glucose, starch, cinnamic acid and stearic acid) to the silt- and clay-sized fraction (fine fraction) of A and B horizons of eight soils from varying climates (3 temperate, 3 tropical, 1 arctic and 1 sub-arctic). Equilibriumbatch experiments were conducted using 0 to 100 mg C L 1 of 14C-labeled compounds for 8 h. Sorption parameters (maximum sorption capacity, Qmax and binding coefficient, k) calculated by fitting sorption data to the Langmuir equation showed that Qmax of A and B horizons was very similar for all compounds. Both Qmax and k values were related to sorbate properties, with Qmax being lowest for glucose (20 500 mg kg 1), highest for stearic acid (20,000 200,000 mg kg 1), and intermediate for both cinnamic acid (200 4000 mg kg 1) and starch (400 6000 mg kg 1). Simple linear regression analysis revealed that physicochemical properties of the sorbents influenced the Qmax of cinnamic acid and stearic acid, but not glucose and starch. The sorbent properties did not show predictive ability for binding coefficient k. By using the fine fraction as sorbent, we found that the mineral fractions of A horizons are equally reactive as the B horizons irrespective of soil organic carbon content.

  6. Microtrapping of volatile organic compounds with carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Chaudhery Mustansar Hussain

    2010-10-01

    Full Text Available Micro-sorbent traps referred to as microtraps serve as integrated concentration-injection devices for continuousmonitoring in gas phase streams. The application of carbon nanotubes as unique sorbents for the fabrication of microtrapsfor the nano-scale adsorption/desorption of volatile organic molecules is presented in this paper. The microtrap applicationrequires high adsorption capacity as well as easy desorbability; the latter being critical for injection mode of these integrateddevices. The micro-sorbent characteristics of single and multi-walled carbon nanotubes for gas phase adsorption/desorptionof several volatile organic compounds like DCM, ethanol and benzene etc. has been studied. The nonporous nature of carbonnanotubes (CNTs eliminates the mass transfer resistance related to diffusion into pore structures, thus allowing easydesorbability. At the same time, their high aspect ratios lead to large breakthrough volumes. As compared to a commercialsorbent carbopackTM, the breakthrough volume was as much as an order of magnitude higher in the CNTs, while the higherrate of desorption measured as the peak width at half height of the desorption band was found nearly eight times lower (i.e.,0.26 seconds with SWNT and 1.89 seconds with carbopackTM. The trapping and desorption characteristics of single andmulti walled nanotubes were found to be comparable. We also found that the presence of disordered carbon impurities,which could be removed by controlled oxidative annealing, could greatly degrade the performance of CNTs. This researchhas suggested that CNTs can be used in micro-sorbent traps and surprisingly enhance the efficiency of the integrated concentration-injection devices. Consequently, this will open the doors to the application of high-capacity, CNTs-based sorbentsas a better alternative to conventional sorbent in continuous monitoring devices.

  7. Synthesis of carbon-14 analogue of 1,5 diaryl-5-[14C]-1,2,3-triazoles

    International Nuclear Information System (INIS)

    Two 1,2,3-triazole anticonvulsants, 1-(4-methylsulfone-phenyl)-5-(4-methyl-phenyl)-1,2,3-triazole and 1-(4-methylsulfone-phenyl)-5-phenyl-1,2,3-triazole, both labeled with carbon-14 in the 5-position were prepared from para-tolunitrile-[cyano-14C] and benzonitrile-[cyano-14C], respectively

  8. Transfer of 14C to prenatal and neonatal rats from their mothers exposed to 14C compounds by ingestion

    International Nuclear Information System (INIS)

    The transfer of 14C through placenta or milk was investigated and the radiation dose to fetal and newborn rats was estimated. Female rats at gestational stages or after delivery were exposed to 14C in the form of sodium bicarbonate, thymidine and lysine by a single ingestion. Radioactivity in maternal tissues and conceptuses (placenta, fetal membrane and fetus) and in the newborn was determined at various times after ingestion. After exposure to these 14C compounds, there was no significant difference between the 14C concentration in the fetus and that in the maternal tissues, suggesting that the placenta has no effect in preventing or accelerating the placental transfer of 14C. The concentration and content of 14C in the fetus and newborn were, however, dependent on the chemical form of 14C and on the prenatal or neonatal stage at the time of ingestion. The result of the dose estimation showed that 14C-lysine gave significantly higher prenatal and neonatal doses than 14C-sodium bicarbonate or 14C-thymidine. (author)

  9. Carbon 14 dating method; Methode de datation par le carbone 14

    Energy Technology Data Exchange (ETDEWEB)

    Fortin, Ph

    2000-07-01

    This document gives a first introduction to {sup 14}C dating as it is put into practice at the radiocarbon dating centre of Claude-Bernard university (Lyon-1 univ., Villeurbanne, France): general considerations and recalls of nuclear physics; the {sup 14}C dating method; the initial standard activity; the isotopic fractioning; the measurement of samples activity; the liquid-scintillation counters; the calibration and correction of {sup 14}C dates; the preparation of samples; the benzene synthesis; the current applications of the method. (J.S.)

  10. Rietveld Refinement of New Ternary Compound Al14Dy5Si

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A new ternary compound Al14Dy5Si was discovered and studied by means of X-ray powder diffraction technique. The ternary compound Al14Dy5Si has a hexagonal BaPb3-type structure, space group R3m(No.166), the lattice parameters a=0.61482(1) nm, c=2.09780(2) nm. The crystal structure of the compound Al14Dy5Si was successfully refined by using Rietveld method from X-ray diffraction data. The R-factors of Rietveld refinement are Rp=0.091 and Rwp=0.120, respectively. The thermal dependence of the magnetization (M-T curves) for the compound was measured by a vibrating sample magnetometer. The experimentally determined magnetic effective paramagnetic moment is μeff=23.22 μB per formula unit (10.36 μB per Dy atom).

  11. Increased root exudation of /sup 14/C-compounds by sorghum seedlings inoculated with nitrogen-fixing bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Lee, K.J. (Institute of Forest Genetics, Suweon (Republic of Korea)); Gaskins, M.H. (Florida Univ., Gainesville (USA). Dept. of Agriculture)

    1982-01-01

    Organic components leaked from Sorghum bicolor seedlings ('root exudates') were examined by recovering /sup 14/C labelled compounds from root solutions of seedlings inoculated with Azospirillum brasilense, Azotobacter vinelandii or Klebsiella pneumoniae nif-. Up to 3.5% of the total /sup 14/C recovered from shoots, roots, and nutrient solutions was found in the root solutions. Inoculation with Azospirillum and Azotobacter increased the amounts of /sup 14/C and decreased the amounts of carbohydrates in the root solutions. When sucrose was added as a carbon source for the bacteria, the increase of /sup 14/C in the solutions did not occur. Quantities of /sup 14/C found in the root solutions were proportional to amounts of mineral nitrogen supplied to the plants. Bacterial growth also was proportional to nitrogen levels. When sorghum plants were grown in soil and labelled with /sup 14/CO/sub 2/, about 15% of the total /sup 14/C recovered within 48 hours exposure was found in soil leachates.

  12. A detective from the past called carbon 14

    International Nuclear Information System (INIS)

    The analysis is carried out using Radiometry or Accelerator mass spectrometry. After the system allowing to date the age of any organic rest - whether a fossil, a wood fragment, a parchment or a seed - is an isotope called carbon-14. An atom that comes from reactions nuclear produced in the atmosphere and cosmic-ray-induced they interact with oxygen to form carbon dioxide. This element they absorb it plants in photosynthesis and then passes to the animals remained almost unchanged during the life of the organism. to the meet the initial ratio of c-14 that had been in the atmosphere before his death, the remains that are left in it determine the elapsed time. (Author)

  13. Behaviour of carbon-14 in graphite irradiated by neutrons

    International Nuclear Information System (INIS)

    The method of carbon-14 extraction from graphite irradiated by neutrons based on the thermal effect to graphite in a technological vacuum or air current is a basically new approach. When irradiated graphite is heated in a technological vacuum and in an air current, extraction of carbon-14 takes place and reaches as much as 99.5%. The mass of graphite decreases approximately by 10% in every 5 hours of heating. At the same time, its substance in different units can vary in wide ranges: from 3,5 to 110 kBq/g. This can be explained in terms of both the different substance of nitrogen impurities in graphite and different fluency of thermal neutrons

  14. Progressive extraction method applied to isotopic exchange of carbon-14

    International Nuclear Information System (INIS)

    Isotopic exchange in natural settings is essentially an irreversible process, so that it progresses continuously until there is complete isotopic equilibrium. In soils, this process involves interaction between isotopes in the liquid and solid phases, and complete isotopic equilibrium may take a very long time. Measurements after partial isotopic exchange have been used to characterize the labile fraction of elements in soils. We describe a method to characterize the extent of isotopic exchange, with application here to incorporation of inorganic carbon-14 (14C) into mineral carbonates and organic matter in soils. The procedure uses a continuous addition of extractant, acid, or H2O2in the examples presented here, coupled with sequential sampling. The method has been applied to demonstrate the degree of isotopic exchange in soil. The same strategy could be applied to many other elements, including plant nutrients. (author)

  15. Sampling and monitoring of carbon-14 in gaseous effluents from nuclear facilities - a literature survey

    International Nuclear Information System (INIS)

    C-14 compounds produced in the coolant may be released mainly together with off-gas and waste water from the coolant purification and treatment system. In reactors the release of C-14 will occur mainly in gaseous effluents and only a few percent in liquid effluents. Reported releases from BWRs range from 260 to 670 GBq/GW(e) x year and from 90 to 430 GBq/GW(e) x year for PWRs. At BWRs the condenser air ejector contributes the main inplant release pathway, whereas in PWRs the off-gas treatment vents are the main pathway for C-14 release. C-14 sampling methods depend generally on the C-14 being in the form of CO2. The off-gas discharges from BWRs are mainly in the form of CO2 whereas in PWRs a major fraction of the released C-14 is in the form of hydrocarbons or carbon monoxide (generally 80-100%). Sampling systems in PWRs should therefore be equipped with a catalytic oxidizer to convert all C-14 to CO2 before trapping. The purpose of this study is to provide information on the techniques available for sampling and monitoring C-14

  16. Radiative Neutron Capture on Carbon-14 in Effective Field Theory

    OpenAIRE

    Rupak, Gautam; Fernando, Lakma; Vaghani, Akshay

    2012-01-01

    The cross section for radiative capture of neutron on carbon-14 is calculated using the model-independent formalism of halo effective field theory. The dominant contribution from E1 transition is considered, and the cross section is expressed in terms of elastic scattering parameters of the effective range expansion. Contributions from both resonant and non-resonant interaction are calculated. Significant interference between these leads to a capture contribution that deviates from simple Bre...

  17. The management of carbon-14 in Canadian nuclear facilities

    International Nuclear Information System (INIS)

    In Canada, Derived Emission Limits (DELs) for the release of radionuclides from nuclear facilities are set to ensure that the dose to a member of a critical group from one year's release does not exceed the limit on annual dose to a member of the public set by the Atomic Energy Control Regulations. The Advisory Committee on Radiological Protection (ACRP) has expressed concerns as to whether this procedure provides adequate protection to members of the public, including future generations, for certain radionuclides such as a carbon-14 (14C), which can accumulate in the environment and which can be dispersed, through environmental processes, beyond the local region where the critical group is assumed to live. The ACRP subsequently established a Working Group to review the production, release, environmental levels, and waste management of 14C arising in CANDU power reactors. The ACRP recommendations resulting from this review can be summarized as · Given the current levels of emissions from CANDU nuclear power stations resulting from the use of a carbon dioxide annulus gas and the limitations in the calculation and use of collective dose, the ACRP sees no need for and additional collective dose limit to be applied to these sources. · The AECB should require licensees of power reactors and waste management sites to provide an annual inventory of 14C held within reactor buildings and waste management sites; to provide information on the stability of the ion exchange resins and their continuing ability to retain the 14C; to demonstrate on an ongoing basis that releases of 14C are maintained at a small fraction of the emission limits; and to report annually the critical group and local collective doses arising from releases of 14C. 61 refs., 25 tabs., 4 figs

  18. Verification of the dispersion model by airborne carbon 14C

    International Nuclear Information System (INIS)

    This paper provides insight in the verification of the Lagrangean dispersion model for dose calculation in the environment. The verification method was based on the measurement of the airborne carbon 14C concentration which can be slightly increased close to the nuclear power plant. The results proved that this method is sensitive enough and that the sensitivity analysis can be used for model verification or for identification of possible improvements of the used meteorological data. The Lagrangean model is used at Krsko nuclear power plant (NPP) for calculation of dispersion coefficients and dose in the environment. To show compliance with the authorized dose limits it is required to present a realistic calculation of the dose to the public. This is a numerical model designed to calculate air pollution dispersion in the area of 25km x 25km. The model uses on-line local meteorological measurements. The same model was already verified for another location around a coal- fired power plant based on emission and environmental measurements of SO2. Krsko NPP is placed near the Sava River in a semiopened basin surrounded by several hills. The region is characterized by low winds and frequent thermal inversions. This paper presents a verification of the short range dispersion model based on the fact that the airborne carbon 14C concentration can be slightly increased close to the nuclear power plant. Other radioactive effluents are not detectable in the environment and carbon 14C measurements are accurate enough to detect small deviations from natural 14C levels and to compare them with the calculated concentration based on 14C effluents. The most of airborne 14C is released during the refuelling outage. Within the pre-selected period of ten days, increased effluents of 14C in the form of CO2 were sampled from the plant ventilation. The average atmospheric dispersion parameters were calculated for two locations in the environment where CO2 sampling plates were installed

  19. Measurements of carbon-14 with cavity ring-down spectroscopy

    Science.gov (United States)

    McCartt, A. D.; Ognibene, T.; Bench, G.; Turteltaub, K.

    2015-10-01

    Accelerator Mass Spectrometry (AMS) is the most sensitive method for quantitation of 14C in biological samples. This technology has been used in a variety of low dose, human health related studies over the last 20 years when very high sensitivity was needed. AMS helped pioneer these scientific methods, but its expensive facilities and requirements for highly trained technical staff have limited their proliferation. Quantification of 14C by cavity ring-down spectroscopy (CRDS) offers an approach that eliminates many of the shortcomings of an accelerator-based system and would supplement the use of AMS in biomedical research. Our initial prototype, using a non-ideal wavelength laser and under suboptimal experimental conditions, has a 3.5-modern, 1- σ precision for detection of milligram-sized, carbon-14-elevated samples. These results demonstrate proof of principle and provided a starting point for the development of a spectrometer capable of biologically relevant sensitivities.

  20. Synthesis of a polycyclic aromatic hydrocarbon marked with carbon-14: (b, d e f) dibenzo-chrysene {sup 14}C-7,14; Synthese d'un hydrocarbure aromatique polycyclique marque au carbone 14: le dibenzo (b, d e f) chrysene {sup 14}C-7,14

    Energy Technology Data Exchange (ETDEWEB)

    Chatelain, G. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-07-01

    (b, d e f) dibenzo-chrysene C-7,14 has been synthesized from radioactive carbon dioxide and the organic magnesium compound derived from 1,5 dibromo naphthalene. The product has been purified by a very precise series of fractionated chromatographs on alumina having a chromatographic activity. This has necessitated the development of a special technique. (author) [French] Le dibenzo (b, d e f) chrysene 14C-7,14 a ete synthetise au depart de gaz carbonique radioactif et de bis-organomagnesien derive du dibromo-1,5 naphtalene. Le produit a ete purifie par une serie de chromatographies fractionnees sur alumine d'activite chromatographique tres precise. Ceci a fait l'objet d'une mise au point de technique. (auteur)

  1. Experimental evaluation of biomass burning emissions: Nitrogen and carbon containing compounds

    International Nuclear Information System (INIS)

    Data are presented on the nitrogen and carbon emissions of biomass burning. The results of the authors' experiments enable them to calculate new source strengths for many compounds, considering different burning stages and fire conditions on the one hand, and different fuel types and properties, on the other hand. They also presented a method for balancing elemental budgets of fires, which had already been described for carbon compounds by other authors but which is new for the nitrogen inventory. Based on their measurements they show that biomass burning contributes significantly to the global budgets of HCN, CH3CN (possibly the major source), NOx (12%), CO(22%), C2 to C4 hydrocarbons (14%), CH3Cl(41%), and probably also to the global source of C1-C5 aliphatic amines. Further, pyrogenic CO2 amounts are likely to represent a substantial contribution to the global greenhouse warming. An important result, from the study is the identification of N2 emissions, which causes a significant loss of fixed nitrogen (pyro-denitrification) in tropical ecosystems in the order of 5% to 20% of the global nitrogen fixation rate. Because of an interesting interplay between an enhanced postfire nitrogen fixation and an enhanced postfire N2O emission, it is not yet known if losses due to pyro-denitrification are balanced by nitrogen fixation

  2. Thermal expansion anomaly and spontaneous magnetostriction of Dy2AlFe14Mn2 compound

    Institute of Scientific and Technical Information of China (English)

    WANG Hai-yun; ZHAO Miao; GAO Yan; ZHOU Yan; FU Bin; YAN Da-li

    2006-01-01

    The structure and magnetic properties of Dy2AlFe14Mn2 compound were investigated by X-ray diffractometry and magnetization measurements. Dy2AlFe14Mn2 compound has a hexagonal Th2Ni17-type structure. Zero thermal expansion and negative thermal expansion were found in Dy2AlFe14Mn2 compound in the temperature range from 184 to 264 K, and from 264 to 383 K, respectively, by X-ray dilatometry. The spontaneous magnetostrictive deformations from 104 to 400 K were calculated. The results show that the spontaneous volume magnetostrictive deformation increases firstly with increasing temperature, and then decreases with furtther increasing temperature.

  3. Investigations on the biokinetics of carbon 14 in algae cultures

    International Nuclear Information System (INIS)

    The uptake of 14C by Scenedesmus quadricauda is quantitatively investigated by simulation models of radio ecological relevance. Due to the complexing of the procedures in the natural ecosystem, it was only possible to consider idealized conditions. The batch culture ressembles the conditons of still waters or relatively still waters without notable water exchange. The effect of the 14C enrichment, as well as the drastic carbon reduction in the substrate as a result of algae growth, was avoided in the modified batch culture under conditions of simultaneous substrate diffusion by means of a permeation system. The 14C and 12C uptake of the cells thus took place solely under the conditions of constant concentration in the culture medium. The consequences for flowing water resulting from a nuclear power plant accident are to be simulated for the extent of the 14C uptake by green algae using the continuous culture model with dynamic 14C exposure. The continuous infusion of 14C in the continuous culture corresponds to the possible cases where 14C escapes into a flowing water at a constant rate over a long period of time, whether this may be via chronical release from a nuclear power plant or by 'fallout' resulting from nuclear arms testing. The results shown lead to the conclusion that the emission of 14C to the environment, which according to prognoses will be considerably higher after the year 2000, presents a serious radioactivity potential which man and environment will have to live with should these developments continue and the prognoses come true. (orig./MG)

  4. A detective from the past called carbon 14; Un detective del pasado llamado carbono 14

    Energy Technology Data Exchange (ETDEWEB)

    Trintan, R. M.

    2015-07-01

    The analysis is carried out using Radiometry or Accelerator mass spectrometry. After the system allowing to date the age of any organic rest - whether a fossil, a wood fragment, a parchment or a seed - is an isotope called carbon-14. An atom that comes from reactions nuclear produced in the atmosphere and cosmic-ray-induced they interact with oxygen to form carbon dioxide. This element they absorb it plants in photosynthesis and then passes to the animals remained almost unchanged during the life of the organism. to the meet the initial ratio of c-14 that had been in the atmosphere before his death, the remains that are left in it determine the elapsed time. (Author)

  5. Hofmann elimination of p-nitrophenylethyl-1-C-14-trimethylammonium bromide: a carbon-14 isotope effect study (Preprint no. AR-24)

    International Nuclear Information System (INIS)

    The alpha carbon isotope effects in the Hofmann elimination of p-nitrophenylethyl-1-C-14-trimethylammonium bromide compound have been measured under changing buffer concentrations with a view to correlate mechanistic change. Since there are alpha-carbon isotope effects and the effects are small it is quite likely that the reaction is of the ElcB type, predominately irreversible, with the incursion of slightly increasing fractions of reaction by the reversible mechanism as the buffer concentration is increased. (author). 4 refs., 2 tab

  6. 14N NQR investigation of some thermochromic and photochromic salicylideneanilines and related compounds

    Science.gov (United States)

    Hadjoudis, E.; Milia, F.; Seliger, J.; Zagar, V.; Blinc, R.

    1991-09-01

    The temperature dependence of the 14N NQR frequencies have been measured in a series of thermochromic and photochromic salicylideneanilines and related compounds using nuclear quadrupole double resonance. The results show that, in agreement with previous measurements, there is a fast exchange between inequivalent sites in the OH…N bond. The energy difference Δ E of the two proton sites was calculated for all the compounds and shows that it depends on their thermochromic behavior which is connected with the structure of the compounds.

  7. High-field magnetic studies of pseudoternary Nd2Fe14B-based compounds

    International Nuclear Information System (INIS)

    The intrinsic properties of some pseudoternary Nd2Fe14B compounds (Nd2Fe13.6Al0.4B, Nd2Fe13.2Al0.8B, Nd2Fe11.2Co2.8B, Nd1.8Dy0.2Fe14B) have been studied by performing high field magnetization measurements at 4.2 K. The magneto-crystalline anisotropy coefficients have been derived. (orig.)

  8. Compound list: carbon tetrachloride [Open TG-GATEs

    Lifescience Database Archive (English)

    Full Text Available carbon tetrachloride CCL4 00003 ftp://ftp.biosciencedbc.jp/archive/open-tggates/LATEST/Human/in_vitro/car...ates/LATEST/Rat/in_vitro/carbon_tetrachloride.Rat.in_vitro.Liver.zip ftp://ftp.biosciencedbc.jp/archive/open...-tggates/LATEST/Rat/in_vivo/Liver/Single/carbon_tetrachloride.Rat.in_vivo.Liver.S...ingle.zip ftp://ftp.biosciencedbc.jp/archive/open-tggates/LATEST/Rat/in_vivo/Liver/Repeat/carbon_tetrachloride.Rat.in_vivo.Liver.Repeat.zip ...

  9. 8-Hydroxynaphthalene-1,4-dione derivative as novel compound for glioma treatment.

    Science.gov (United States)

    Zagotto, Giuseppe; Redaelli, Marco; Pasquale, Riccardo; D'Avella, Domenico; Cozza, Giorgio; Denaro, Luca; Pizzato, Francesca; Mucignat-Caretta, Carla

    2011-04-01

    Malignant gliomas continue to demand the search for improved chemotherapeutic solutions. In this work the results of a preliminary in vitro screening performed on a small library of compounds are disclosed. As a result 2-(2,4-dihydroxyphenyl)-8-hydroxy-1,4-naphthoquinone emerged as a promising therapeutic lead. PMID:21353776

  10. Compound specific radiocarbon analyses to apportion sources of combustion products in sedimentary pyrogenic carbon deposits

    Science.gov (United States)

    Hanke, Ulrich M.; Schmidt, Michael W. I.; McIntyre, Cameron P.; Reddy, Christopher M.; Wacker, Lukas; Eglinton, Timothy I.

    2016-04-01

    Pyrogenic carbon (PyC) is a collective term for carbon-rich residues comprised of a continuum of products generated during biomass burning and fossil fuel combustion. PyC is a key component of the global carbon cycle due to its slow intrinsic decomposition rate and its ubiquity in the environment. It can originate from natural or anthropogenic vegetation fires, coal mining, energy production, industry and transport. Subsequently, PyC can be transported over long distances by wind and water and can eventually be buried in sediments. Information about the origin of PyC (biomass burning vs. fossil fuel combustion) deposited in estuarine sediments is scarce. We studied the highly anoxic estuarine sediments of the Pettaquamscutt River (Rhode Island, U.S.) in high temporal resolution over 250 years and found different combustion proxies reflect local and regional sources of PyC (Hanke et al. in review; Lima et al. 2003). The polycyclic aromatic hydrocarbons (PAH) originate from long-range atmospheric transport, whereas bulk PyC, detected as benzene polycarboxylic acids (BPCA), mainly stems from local catchment run-off. However, to unambiguously apportion PyC sources, we need additional information, such as compound specific radiocarbon (14C) measurements. We report 14C data for individual BPCA including error analysis and for combustion-related PAH. First results indicate that biomass burning is the main source of PyC deposits, with additional minor contributions from fossil fuel combustion. References Hanke U.M., T.I. Eglinton, A.L.L. Braun, C. Reddy, D.B. Wiedemeier, M.W.I. Schmidt. Decoupled sedimentary records of combustion: causes and implications. In review. Lima, A. L.; Eglinton, T. I.; Reddy, C. M., High-resolution record of pyrogenic polycyclic aromatic hydrocarbon deposition during the 20th century. ES&T, 2003, 37 (1), 53-61.

  11. Characterization, Quantification and Compound-specific Isotopic Analysis of Pyrogenic Carbon Using Benzene Polycarboxylic Acids (BPCA).

    Science.gov (United States)

    Wiedemeier, Daniel B; Lang, Susan Q; Gierga, Merle; Abiven, Samuel; Bernasconi, Stefano M; Früh-Green, Gretchen L; Hajdas, Irka; Hanke, Ulrich M; Hilf, Michael D; McIntyre, Cameron P; Scheider, Maximilian P W; Smittenberg, Rienk H; Wacker, Lukas; Wiesenberg, Guido L B; Schmidt, Michael W I

    2016-01-01

    Fire-derived, pyrogenic carbon (PyC), sometimes called black carbon (BC), is the carbonaceous solid residue of biomass and fossil fuel combustion, such as char and soot. PyC is ubiquitous in the environment due to its long persistence, and its abundance might even increase with the projected increase in global wildfire activity and the continued burning of fossil fuel. PyC is also increasingly produced from the industrial pyrolysis of organic wastes, which yields charred soil amendments (biochar). Moreover, the emergence of nanotechnology may also result in the release of PyC-like compounds to the environment. It is thus a high priority to reliably detect, characterize and quantify these charred materials in order to investigate their environmental properties and to understand their role in the carbon cycle. Here, we present the benzene polycarboxylic acid (BPCA) method, which allows the simultaneous assessment of PyC's characteristics, quantity and isotopic composition ((13)C and (14)C) on a molecular level. The method is applicable to a very wide range of environmental sample materials and detects PyC over a broad range of the combustion continuum, i.e., it is sensitive to slightly charred biomass as well as high temperature chars and soot. The BPCA protocol presented here is simple to employ, highly reproducible, as well as easily extendable and modifiable to specific requirements. It thus provides a versatile tool for the investigation of PyC in various disciplines, ranging from archeology and environmental forensics to biochar and carbon cycling research. PMID:27214064

  12. Characterization, Quantification and Compound-specific Isotopic Analysis of Pyrogenic Carbon Using Benzene Polycarboxylic Acids (BPCA)

    Science.gov (United States)

    Wiedemeier, Daniel B.; Lang, Susan Q.; Gierga, Merle; Abiven, Samuel; Bernasconi, Stefano M.; Früh-Green, Gretchen L.; Hajdas, Irka; Hanke, Ulrich M.; Hilf, Michael D.; McIntyre, Cameron P.; Scheider, Maximilian P. W.; Smittenberg, Rienk H.; Wacker, Lukas; Wiesenberg, Guido L. B.; Schmidt, Michael W. I.

    2016-01-01

    Fire-derived, pyrogenic carbon (PyC), sometimes called black carbon (BC), is the carbonaceous solid residue of biomass and fossil fuel combustion, such as char and soot. PyC is ubiquitous in the environment due to its long persistence, and its abundance might even increase with the projected increase in global wildfire activity and the continued burning of fossil fuel. PyC is also increasingly produced from the industrial pyrolysis of organic wastes, which yields charred soil amendments (biochar). Moreover, the emergence of nanotechnology may also result in the release of PyC-like compounds to the environment. It is thus a high priority to reliably detect, characterize and quantify these charred materials in order to investigate their environmental properties and to understand their role in the carbon cycle. Here, we present the benzene polycarboxylic acid (BPCA) method, which allows the simultaneous assessment of PyC's characteristics, quantity and isotopic composition (13C and 14C) on a molecular level. The method is applicable to a very wide range of environmental sample materials and detects PyC over a broad range of the combustion continuum, i.e., it is sensitive to slightly charred biomass as well as high temperature chars and soot. The BPCA protocol presented here is simple to employ, highly reproducible, as well as easily extendable and modifiable to specific requirements. It thus provides a versatile tool for the investigation of PyC in various disciplines, ranging from archeology and environmental forensics to biochar and carbon cycling research. PMID:27214064

  13. Quantification of biogenic volatile organic compounds with a flame ionization detector using the effective carbon number concept

    Science.gov (United States)

    Faiola, C. L.; Erickson, M. H.; Fricaud, V. L.; Jobson, B. T.; VanReken, T. M.

    2012-08-01

    Biogenic volatile organic compounds (BVOCs) are emitted into the atmosphere by plants and include isoprene, monoterpenes, sesquiterpenes, and their oxygenated derivatives. These BVOCs are among the principal factors influencing the oxidative capacity of the atmosphere in forested regions. BVOC emission rates are often measured by collecting samples onto adsorptive cartridges in the field and then transporting these samples to the laboratory for chromatographic analysis. One of the most commonly used detectors in chromatographic analysis is the flame ionization detector (FID). For quantitative analysis with an FID, relative response factors may be estimated using the effective carbon number (ECN) concept. The purpose of this study was to determine the ECN for a variety of terpenoid compounds to enable improved quantification of BVOC measurements. A dynamic dilution system was developed to make quantitative gas standards of VOCs with mixing ratios from 20-55 ppb. For each experiment using this system, one terpene standard was co-injected with an internal reference, n-octane, and analyzed via an automated cryofocusing system interfaced to a gas chromatograph flame ionization detector and mass spectrometer (GC/MS/FID). The ECNs of 16 compounds (14 BVOCs) were evaluated with this approach, with each test compound analyzed at least three times. The difference between the actual carbon number and measured ECN ranged from -24% to -2%. The difference between theoretical ECN and measured ECN ranged from -22% to 9%. Measured ECN values were within 10% of theoretical ECN values for most terpenoid compounds.

  14. Determination of carbon in uranium and its compounds

    International Nuclear Information System (INIS)

    This paper collects the analytical methods used our laboratories for the determination of carbon in uranium metal, uranate salts and the oxides, fluorides and carbides of uranium. The carbon is usually burned off in a induction or resistance oven under oxygen flow. The CO2 is collected in barite solution. Where it is backtitrated with potassium biphthalate. (Author)

  15. Study on behavior and treatment of radioiodine and carbon-14 at reprocessing of spent fuels

    International Nuclear Information System (INIS)

    Treatment of dissolver Off-gas (DOG) is one of important operation in the head-end process of spent fuel reprocessing. Radioiodine, carbon-14 are contained in the DOG. Confinement of radioiodine is required and the reduction of carbon-14 will be required following ALARA principle. In the present study spent fuel dissolution and off-gas treatment tests were carried out using spent fuel with burnups of 8,000 , 29,000 and 44,000 MWd·t-1. Behavior of radioiodine and carbon-14 was investigated. In addition, several adsorbents for carbon dioxide to capture carbon-14 from the DOG were tested in a cold equipment. (author)

  16. Carbon dioxide laser absorption spectra of toxic industrial compounds

    International Nuclear Information System (INIS)

    CO2 laser absorption cross-section data are reported for acrolein, styrene, ethyl acrylate, trichloroethylene, vinyl bromide, and vinylidene chloride. These data indicate that sub parts per billion level, interference-free detection limits should be possible for these compounds by the CO2 laser photoacoustic technique. Photoacoustic detectabilities below 40 ppb should be possible for these compounds in the presence of ambient air concentrations of water vapor and other anticipated interferences. These compounds are also found not to be important inerference in the detection of toxic hydrazine-based rocket fuels by CO2 laser spectroscopic techniques

  17. The future radiological burden due to carbon 14

    International Nuclear Information System (INIS)

    The global cycling of carbon dioxide from the combustion of fossil fuels and of radiocarbon released from nuclear power facilities has been simulated using a seven-box-model. The model is built up by two boxes for the atmosphere (stratosphere, troposphere), three boxes for the ocean (mixed surface layer, deep sea and sediments), and two boxes for the biosphere (short- and long-lived biota) with non-linear troposphere-biota and troposphere-ocean surface layer exchange rates and linear fluxes between the other reservoirs. The biota growth factor, the exchange of the atmospheric CO2 with the ocean, and the preindustrial atmospheric CO2 content were fitted using the records of the atmospheric CO2 concentration in Mauna Loa, the Suess-effect until 1954, and the response to the C-14 from nuclear weapons tests. The two scenarios considered are (I) annual energy growth rates of 2% and 4%, no nuclear power; (II) a upper and lower estimate of C-14 releases and a best estimate without retention and with a retention factor of four at the fuel reprocessing plants. Assuming logistic source functions for the increase of fossil fuel combustion and an exponentiel growth of nuclear power until the year 2020, the CO2 concentration of the troposphere reaches the 2-5 fold of the preindustrial level around 2100. Simultaneously, the specific C-14 activity of the atmosphere is decreased. The individual lifetime dose commitments (70 y) are found between 0.85 and 0.45 mSv (natural values: 0.73 mSv) and the collective dose commitments until 2100 are about 10% of those due to naturally produced C-14. (orig.)

  18. The test of carbon 14C introducing to sugar beet plant

    International Nuclear Information System (INIS)

    The carbon 14 was introduced to sugar beet plant by photosynthesis. The changes of radioactivity were investigated. It was stated that lower 25 % of carbon 14 stay in leaves, and about 75 % flow to roots in the form of sucrose 14C. (author)

  19. Mechanisms of Microwave Absorption in Carbon Compounds from Shungite

    OpenAIRE

    S. Emelyanov; A. Kuzmenko; V. Rodionov; M. Dobromyslov

    2013-01-01

    According to SEM, X-ray phase analysis, Raman scattering data features of nanostructural changes in shungite carbon structure were found when processing shungite in 52 % hydrofluoric acid. It is found that conductivity increases up to the values of electrical graphite and absorption of microwave radiation also increases at frequencies up to 40 GHz, which, along with dielectric losses, is due to intense processes of both scattering at laminar carbon structures and absorption of electromagnetic...

  20. Mechanisms of Microwave Absorption in Carbon Compounds from Shungite

    Directory of Open Access Journals (Sweden)

    S. Emelyanov

    2013-12-01

    Full Text Available According to SEM, X-ray phase analysis, Raman scattering data features of nanostructural changes in shungite carbon structure were found when processing shungite in 52 % hydrofluoric acid. It is found that conductivity increases up to the values of electrical graphite and absorption of microwave radiation also increases at frequencies up to 40 GHz, which, along with dielectric losses, is due to intense processes of both scattering at laminar carbon structures and absorption of electromagnetic energy.

  1. Influence of Mn substitution on the magnetic properties of Ho2Fe14C compounds

    International Nuclear Information System (INIS)

    The crystallographic and magnetic properties of the compounds Ho2Fe14-xMnxC have been investigated by means of x-ray diffraction and magnetic measurements. Magnetization measurements made in fields up to 38 T showed that the saturation moment exhibits a minimum at a Mn concentration corresponding to about x=2. The occurrence of this minimum is explained by antiparallel coupling between the Ho and 3d sublattice magnetization, the latter becoming strongly reduced with increasing Mn concentration. Most of the Ho2Fe14-xMnxC compounds investigated have a break in the magnetization curves measured at 4.2 K. This break is interpreted as the onset of decoupling between the antiparallel coupling between the rare-earth and 3d sublattice. A mean-field analysis was used to derive the intersublattice molecular-field coefficients nRT

  2. Electronic structure and magnetism of AFe2 compounds with C14 and C15 laves structures

    International Nuclear Information System (INIS)

    The d-band densities of states are calculated by the recursion method for the paramagnetic AFe2 compounds with C14 and C15 structures, where A is occupied by 3d (Sc, Ti, V), 4d (Y, Zr, Nb) or 5d (Lu, Hf, Ta) series' elements. The densities of states of the ferromagnetic and antiferromagnetic (Zr/sub 1-x/Nb/sub x/)Fe2 compounds with C15 and C14 structures are calculated. The pseudobinary systems are treated within a virtual crystal approximation. The trends of the crystal structures are related to the d electron number around the A site. Magnetic moment and spontaneous volume magnetostriction are calculated on the basis of the Stoner theory. (author)

  3. Carbon Nanomaterials Based Electrochemical Sensors/Biosensors for the Sensitive Detection of Pharmaceutical and Biological Compounds

    OpenAIRE

    Bal-Ram Adhikari; Maduraiveeran Govindhan; Aicheng Chen

    2015-01-01

    Electrochemical sensors and biosensors have attracted considerable attention for the sensitive detection of a variety of biological and pharmaceutical compounds. Since the discovery of carbon-based nanomaterials, including carbon nanotubes, C60 and graphene, they have garnered tremendous interest for their potential in the design of high-performance electrochemical sensor platforms due to their exceptional thermal, mechanical, electronic, and catalytic properties. Carbon nanomaterial-based el...

  4. Supercritical Carbon Dioxide and Microwave-Assisted Extraction of Functional Lipophilic Compounds from Arthrospira platensis

    Directory of Open Access Journals (Sweden)

    Diego A. Esquivel-Hernández

    2016-05-01

    Full Text Available Arthrospira platensis biomass was used in order to obtain functional lipophilic compounds through green extraction technologies such as supercritical carbon dioxide fluid extraction (SFE and microwave-assisted extraction (MAE. The temperature (T factor was evaluated for MAE, while for SFE, pressure (P, temperature (T, and co-solvent (ethanol (CS were evaluated. The maximum extraction yield of the obtained oleoresin was (4.07% ± 0.14% and (4.27% ± 0.10% for SFE and MAE, respectively. Extracts were characterized by gas chromatography mass spectrometry (GC-MS and gas chromatography flame ionization detector (GC-FID. The maximum contents of functional lipophilic compounds in the SFE and MAE extracts were: for carotenoids 283 ± 0.10 μg/g and 629 ± 0.13 μg/g, respectively; for tocopherols 5.01 ± 0.05 μg/g and 2.46 ± 0.09 μg/g, respectively; and for fatty acids 34.76 ± 0.08 mg/g and 15.88 ± 0.06 mg/g, respectively. In conclusion, the SFE process at P 450 bar, T 60 °C and CS 53.33% of CO2 produced the highest yield of tocopherols, carotenoids and fatty acids. The MAE process at 400 W and 50 °C gives the best extracts in terms of tocopherols and carotenoids. For yield and fatty acids, the MAE process at 400 W and 70 °C produced the highest values. Both SFE and MAE showed to be suitable green extraction technologies for obtaining functional lipophilic compounds from Arthrospira platensis.

  5. Supercritical Carbon Dioxide and Microwave-Assisted Extraction of Functional Lipophilic Compounds from Arthrospira platensis

    Science.gov (United States)

    Esquivel-Hernández, Diego A.; López, Víctor H.; Rodríguez-Rodríguez, José; Alemán-Nava, Gibrán S.; Cuéllar-Bermúdez, Sara P.; Rostro-Alanis, Magdalena; Parra-Saldívar, Roberto

    2016-01-01

    Arthrospira platensis biomass was used in order to obtain functional lipophilic compounds through green extraction technologies such as supercritical carbon dioxide fluid extraction (SFE) and microwave-assisted extraction (MAE). The temperature (T) factor was evaluated for MAE, while for SFE, pressure (P), temperature (T), and co-solvent (ethanol) (CS) were evaluated. The maximum extraction yield of the obtained oleoresin was (4.07% ± 0.14%) and (4.27% ± 0.10%) for SFE and MAE, respectively. Extracts were characterized by gas chromatography mass spectrometry (GC-MS) and gas chromatography flame ionization detector (GC-FID). The maximum contents of functional lipophilic compounds in the SFE and MAE extracts were: for carotenoids 283 ± 0.10 μg/g and 629 ± 0.13 μg/g, respectively; for tocopherols 5.01 ± 0.05 μg/g and 2.46 ± 0.09 μg/g, respectively; and for fatty acids 34.76 ± 0.08 mg/g and 15.88 ± 0.06 mg/g, respectively. In conclusion, the SFE process at P 450 bar, T 60 °C and CS 53.33% of CO2 produced the highest yield of tocopherols, carotenoids and fatty acids. The MAE process at 400 W and 50 °C gives the best extracts in terms of tocopherols and carotenoids. For yield and fatty acids, the MAE process at 400 W and 70 °C produced the highest values. Both SFE and MAE showed to be suitable green extraction technologies for obtaining functional lipophilic compounds from Arthrospira platensis. PMID:27164081

  6. Compound-specific stable carbon isotope ratios of phenols and nitrophenols derivatized with N,O-bis(trimethylsilyl)trifluoroacetamide

    International Nuclear Information System (INIS)

    Graphical abstract: -- Highlights: •For GCC–IRMS analysis, an approach avoiding impact of NO2 on δ13C was demonstrated. •Carbon isotope fractionations during derivatizing reactions here were negligible. •Except some labile compounds, the overall bias of the method here was −0.21‰. •Even for the labile compounds, measurement biases ranged +1.2‰ to −1.4‰. •Real sample analysis demonstrates usefulness of the method for fractionation study. -- Abstract: We developed an analytical method for measuring compound-specific stable carbon isotope ratios (δ13C) of phenols and nitrophenols in filter samples of particulate organic matter. The method was tested on 13 phenols derivatized with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA), together with four nonphenolic compounds. The data obtained by our method required two specific corrections for the determination of valid δ13C values: (1) for nitro compounds, the routine correction with use of m/z 46 for the contribution of 12C17O16O molecules) to m/z 45 was modified due to impact of NO2 on the m/z 46 trace, and (2) for the derivatized phenols, measured δ13C values were corrected for the shift in δ13C due to the addition of carbon atoms from the BSTFA moiety. Analysis of standard-spiked filters showed that overall there was a small compound-dependent bias in the δ13C values: the average bias ± the standard error of the mean of −0.21 ± 0.1‰ for the standard compounds tested, except 3-methylcatechol, methylhydroquinone, 4-methyl-2-nitrophenol, and 2,6-dimethyl-4-nitrophenol, whereas the average biases ± the standard errors of the mean for those were +1.2 ± 0.3‰, +1.2 ± 0.2‰, −1.2 ± 0.2‰, and −1.4 ± 0.5‰, respectively, when the injected mass of a derivatized compound exceeded 15 ngC. In situations where such small biases and uncertainties are acceptable, the method described here could be used to obtain valuable information about δ13C values. We also analyzed a real filter

  7. Carbonates in leaching reactions in context of 14C dating

    Science.gov (United States)

    Michalska, Danuta; Czernik, Justyna

    2015-10-01

    Lime mortars as a mixture of binder and aggregate may contain carbon of various origins. If the mortars are made of totally burnt lime, radiocarbon dating of binder yields the real age of building construction. The presence of carbonaceous aggregate has a significant influence on the 14C measurements results and depending on the type of aggregate and fraction they may cause overaging. Another problem, especially in case of hydraulic mortars that continue to be chemically active for a very long time, is the recrystallization usually connected with rejuvenation of the results but also, depending on local geological structures, with so called reservoir effect yielding apparent ages. An attempt in separating the binder from other carbonaceous components successfully was made for samples from Israel by Nawrocka-Michalska et al. (2007). The same preparation procedure, after taking into account the petrographic composition, was used for samples coming from Poland, Nawrocka et al. (2009). To verify the procedure used previously for non-hydraulic samples determination an experimental tests on carbonaceous mortars with crushed bricks from Novae in Bulgaria were made. Additionally, to identify different carbonaceous structures and their morphology, a cathodoluminescence and scanning electron microscope with electron dispersive spectrometer were applied. The crushed bricks and brick dust used in mortars production process have been interpreted as an alternative use to other pozzolanic materials. The reaction between lime and pozzolanic additives take place easily and affects the rate and course of carbonates decomposition in orthophosphric acid, during the samples pretreatment for dating. The composition of the Bulgarian samples together with influence of climate conditions on mortar carbonates do not allow for making straightforward conclusions in chronology context, but gives some new guidelines in terms of hydraulic mortars application for dating. This work has mainly

  8. Thermal Expansion Anomaly and Spontaneous Magnetostriction of Y2Fe14Al3Compound

    Institute of Scientific and Technical Information of China (English)

    HAO Yan-Ming; ZHANG Yan-Yan; JIANG Xin-Yuan; GAO Chun-Jing; WU Yan-Zhao

    2009-01-01

    The structure and magnetic properties of Y2Fe14Al3 compound are investigated by means of x-ray diffraction and magnetization measurements. The Y2Fe14.Al3 compound has a hexagonal Th2Ni17-type structure. Nega-tive thermal expansion is found in Y2Fe14Al3 compound in the temperature range from 403 to 491K by x-ray dilatometry. The coefficient of the average thermal expansion is α = -2.54 × 10-5 K-1. The spontaneous mag-netostrictive deformations from 283 to 470 K are calculated by means of the differences between the experimental values of the lattice parameters and the corresponding values extrapolated from the paramagnetic range. The result shows that the spontaneous volume magnetostrictive deformation ωs decreases from 5.74 × 10-3 to nearly zero with temperature increasing from 283 to 470K, the spontaneous linear magnetostrictive deformation λc along the c-axis is larger than the spontaneous linear magnetostrictive deformation λα in basal-plane in the same temperature below 350K.

  9. The preparation of glucose uniformly labelled with carbon-14; Preparacion de glucosa uniformemente marcada con carbono-14

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, M. D.; Suarez, C.; Rodrigo, M. E.

    1978-07-01

    The plant, (Zea mais, L) and culture conditions for an optimum production of glucose has been chosen. To achieve the labelling of glucose, photosynthesis and carboxylation are carried on, under an artificial atmosphere of 14CO{sub 2} produced from 14{sup C}-barium carbonate. Following photosynthesis the sugars are extracted, and then the extract purified by several methods. The purified glucose is finally, degraded and the specific radioactivity is determined in each of its carbon atoms. (Author) 37 refs.

  10. Chemical and biological evolution of (U-14C)phenol sorbed on activated carbon

    International Nuclear Information System (INIS)

    Methods describing the chemical and biological evolution of (U-14C)phenol adsorbed on activated carbon are given with or without the use of bacteria. Without bacteria, the (U-14C)phenol initially adsorbed is not removed from the carbon after adding a solution of unlabelled phenol through the column for eight days. With bacteria, the (U-14C)phenol initially present, is removed (60-70%) from activated carbon with a solution containing unlabelled phenol, nitrogen and phosphorus. (author)

  11. Globally stable structures of LixZn (x = 1-4) compounds at high pressures.

    Science.gov (United States)

    Bi, Haixin; Zhang, Shoutao; Wei, Shubo; Wang, Jianyun; Zhou, Dan; Li, Quan; Ma, Yanming

    2016-02-01

    Pressure can change the properties of atoms and bonding patterns, leading to the synthesis of novel compounds with interesting properties. The intermetallic lithium-zinc (Li-Zn) compounds have attracted increasing attention because of their fascinating mechanical properties and widespread applications in rechargeable Li-ion batteries. Using the effective CALYPSO searching method in combination with first-principles calculations, we theoretically investigated the LixZn (x = 1-4) compounds at pressures of 0 to 100 GPa. We found several stable structures with a variety of stoichiometries and the phase diagram on the Li-rich side under high pressure. The electronic structures of these compounds reveal transferred charges from lithium to zinc mainly fill Zn 4p states and compounds with negatively charged Zn atoms are dramatic. We also calculated the elastic constants to discuss their mechanical properties. Our results enrich the crystal structures of the Li-Zn system and provide a further understanding of structural features and their properties. PMID:26791574

  12. Uptake of bomb-produced carbon-14 by the Pacific Ocean

    International Nuclear Information System (INIS)

    Collection of seawater samples for carbon-14 analysis was performed from 1957 through 1972. The dissolved inorganic carbon was extracted on board the ships and returned to the laboratory for processing. Samples were analyzed for carbon-14 by gas proportional counting of acetylene prepared by conversion of carbon dioxide to acetylene via lithium carbide. Carbon-14 results are reported for 312 surface and 96 sub-surface Pacific Ocean samples and for 34 surface and 53 sub-surface Indian Ocean samples. The precision of measurements was generally from 0.5 to 1.5 percent (one-sigma). The purpose of the seawater measurements was to determine the distribution of bomb carbon-14 in the surface of the Pacific and Indian Oceans, the change in carbon-14 concentration with depth, and the rate of uptake of bomb carbon-14 by the oceans. The oceans are the largest reservoir of exchangeable carbon. The CO2 of the atmosphere exchanges with that of the sea through molecular exchange. In the surface Pacific, a strong latitudinal variation in carbon-14 concentration was found. By 1971, maxima of about 25 percent above pre-bomb levels were found at mid-latitudes of both hemispheres; this finding is attributed to relatively weak vertical mixing in the gyral circulation systems. A 1971 equatorial excess of only about 11 percent is caused by upwelling of sub-surface water and mixture of low carbon-14 Peru Current water into the equatorial system. South of the Antarctic Convergence surface radiocarbon levels rapidly decrease. To the North of the North Pacific gyre maximum, carbon-14 levels show a minimum at about 400N, apparently due to an influx of low carbon-14 water from north of Japan. Levels then rise to a maximum at 450N to 480N, before decreasing further north

  13. Use of the small proportional counter for carbon 14 measurement in 10 milligram carbon samples

    International Nuclear Information System (INIS)

    Ten years ago, the measurement of C-14/C-12 ratios in 10 milligram carbon samples seemed to be technically out of reach. However, two developments that make this goal possible have recently occurred: the first is an entirely new mass-spectrometric separation of C-14 and C-12 ions and their subsequent estimation by counting, while the second is simply the extension of conventional proportional counter operation (using CO2 as counter gas) to very small size carbon samples. The first method is very fast, precise, and capable of treating samples of even sub-milligram size, but requires an expensive installation. The second method is slow (counting times of two months or more are necessary), can probably be made sufficiently precise to handle most problems, works down to sample sizes of 10 mg carbon, and is relatively inexpensive, especially to install in already existing radiocarbon laboratories. It is this second method and its implications that are discussed in the present paper

  14. Synthesis of Carbon Nanotubes and Volatile Organic Compounds Detection

    OpenAIRE

    Sobri S.; Jasni J.; Yasin Faizah M.; Jamal Siti Hasnawati; Janudin Nurjahirah; Mohd Kasim Noor Azilah

    2016-01-01

    In this work, the adsorption effect of volatile organic compounds (chloroacetophenone, acetonitrile and hexane) towards the change of resistance of CNTs pellet as sensor signal was investigated. CNTs used in this research were synthesized using Floating Catalyst – Chemical Vapor Deposition (FC-CVD) method in optimum condition. The synthesized CNTs were characterized using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Raman Spectroscopy. The variation of resist...

  15. Microtrapping of volatile organic compounds with carbon nanotubes

    OpenAIRE

    Chaudhery Mustansar Hussain; Chutarat Saridara; Somenath Mitra

    2010-01-01

    Micro-sorbent traps referred to as microtraps serve as integrated concentration-injection devices for continuousmonitoring in gas phase streams. The application of carbon nanotubes as unique sorbents for the fabrication of microtrapsfor the nano-scale adsorption/desorption of volatile organic molecules is presented in this paper. The microtrap applicationrequires high adsorption capacity as well as easy desorbability; the latter being critical for injection mode of these integrateddevices. Th...

  16. Pharmacokinetic and metabolic study of the compound GYKI-32 594 labelled with 14C

    International Nuclear Information System (INIS)

    Resorption, blood serum level, tissue distribution and elimination of the 14C-labelled antiserotonin drug 1-methyl-9,10-dihydro-lisergic acid (2'-thiazole-2-il/-amid)bimaleinate were investigated in rats. The compound is resorbed both from the stomach and the small intestine (in two hours 22.5% and 83.8%, resp.). The serum level quickly decreases, Tsub(1/2) being 1.4 - 2.8 hours, depending on the administered dose. Cumulative administration does not increase the serum level. The highest activity was found in the liver and kidneys, but in the brain no radioactivity could be detected. Elimination occurred through the urine (31.7%) and the faeces (23.7%); the enterohepatic circulation was not significant. The compound penetrates into the placenta and appears in the mother's milk. Both in the serum and the urine only a minor part (11-15%) of the radioactivity is represented by the original compound; 4 other metabolites are present. (L.E.)

  17. Synthesis of Carbon Nanotubes and Volatile Organic Compounds Detection

    Directory of Open Access Journals (Sweden)

    Sobri S.

    2016-01-01

    Full Text Available In this work, the adsorption effect of volatile organic compounds (chloroacetophenone, acetonitrile and hexane towards the change of resistance of CNTs pellet as sensor signal was investigated. CNTs used in this research were synthesized using Floating Catalyst – Chemical Vapor Deposition (FC-CVD method in optimum condition. The synthesized CNTs were characterized using Scanning Electron Microscopy (SEM, Transmission Electron Microscopy (TEM and Raman Spectroscopy. The variation of resistance changes towards the tested gases were recorded using a multimeter. CNTs sensor pellet showed good responses towards the tested gases, however, the sensitivity, response time and recovery time of sensor pellet need to be optimized.

  18. Moessbauer spectroscopy of R2Fe14B and related compounds

    International Nuclear Information System (INIS)

    The Moessbauer Spectroscopy (MBS) has been widely used in the last 4 years for the study of the recently discovered ternary compounds R2F14B where R means Y, Th or a rare earth element. The strong interest for this class of intermetallics arose drastically after the discovery of the exceptional properties of Nd2Fe14 as an ideal material for permanent magnet applications. The newest results about hyperfine fields BHF, quadrupole splitting EQ and isomer shifts I.S. at the 6 crystallographically different Fe sites and at the 2 R sites in the R2F14B and their impact on the understanding of the local magnetic moments and magnetocrystalline anisotropy will be reviewed. In the case of RFe12-xMx compounds where M = V, Ti, Si, Mo, W, Cr, complex Moessbauer spectra were obtained because of the presence of 3 crystallographically inequivalent Fe sites and the presence of differents amounts of the M component on one or more of these sites. (orig.)

  19. Thermal and structural study on the lattice compound 1,4-diammoniumbutane bis(theophyllinate)

    International Nuclear Information System (INIS)

    Crystalline title compound (1) prepared from aqueous solution of theophylline and 1,4-diaminobutane has been structurally and thermally characterized. Both the two-step TG decomposition curve and elemental analysis of the hexagonal crystals show that it consists of theophylline and 1,4-diaminobutane in 2:1 molar ratio. Actually, presence of one type of both theophyllinate anions and 1,4-diammoniumbutane dication have been indicated by FTIR spectroscopy. The molecular structure of lattice compound (1) has been determined by single crystal X-ray diffraction, where the hydrogen positions have been obtained from differential Fourier maps. It has confirmed that the crystal is really built up from these ionic constituents bound together with an extensive net of hydrogen bonds. The coupled TG-FTIR analysis of the evolved gases has revealed that the diamine is released as a whole molecule in the first decomposition step. Clathrate 1 and the proton migration in it might serve as a structural model of solid aminophylline whose crystal structure is still unknown

  20. Thermal and structural study on the lattice compound 1,4-diammoniumbutane bis(theophyllinate)

    Energy Technology Data Exchange (ETDEWEB)

    Ban, Margit; Madarasz, Janos; Bombicz, Petra; Pokol, Gyoergy; Gal, Sandor

    2004-10-01

    Crystalline title compound (1) prepared from aqueous solution of theophylline and 1,4-diaminobutane has been structurally and thermally characterized. Both the two-step TG decomposition curve and elemental analysis of the hexagonal crystals show that it consists of theophylline and 1,4-diaminobutane in 2:1 molar ratio. Actually, presence of one type of both theophyllinate anions and 1,4-diammoniumbutane dication have been indicated by FTIR spectroscopy. The molecular structure of lattice compound (1) has been determined by single crystal X-ray diffraction, where the hydrogen positions have been obtained from differential Fourier maps. It has confirmed that the crystal is really built up from these ionic constituents bound together with an extensive net of hydrogen bonds. The coupled TG-FTIR analysis of the evolved gases has revealed that the diamine is released as a whole molecule in the first decomposition step. Clathrate 1 and the proton migration in it might serve as a structural model of solid aminophylline whose crystal structure is still unknown.

  1. Synthesis of carbon-14 labelled indolic 5HT{sub 1} receptor agonists

    Energy Technology Data Exchange (ETDEWEB)

    Waterhouse, Ian; Cable, K.M.; Fellows, Ian; Wipperman, M.D.; Sutherland, D.R. [Glaxo Wellcome Research and Development, Stevenage (United Kingdom). Isotope Chemistry Unit

    1996-11-01

    Syntheses of carbon-14 labelled versions of indolic 5HT{sub 1} agonists sumatriptan (GR43175), GR40370 and naratriptan (GR85548) are described. Introduction of the label via cyanation of ketoformanilides, formed by oxidative cleavage of an indole ring, ensured incorporation of carbon-14 at the metabolically stable C-2 position of the indole. (author).

  2. Modeling the heat and mass transfers in temperature-swing adsorption of volatile organic compounds onto activated carbons

    Energy Technology Data Exchange (ETDEWEB)

    Sylvain Giraudet; Pascaline Pre; Pierre Le Cloirec [Ecole des Mines de Nantes, Nantes (France)

    2009-02-15

    A theoretical model was built to simulate the adsorption of volatile organic compounds (VOCs) onto activated carbons in a fixed bed. This model was validated on a set of experimental data obtained for the adsorption of acetone, ethyl formate, and dichloromethane onto five commercial activated carbons. The influence of operating conditions was modeled with various VOC contents at the inlet of the adsorber and superficial velocities of the gas-phase from 0.14 to 0.28 m.s{sup -1}. Breakthrough times and maximum temperature rises were computed with a coefficient of determination of 0.988 and 0.901, respectively. The simulation was then extended to the adsorption of mixtures of VOCs. From the comparison of simulation and experimental results, the advantage of accounting for dispersions of heat and mass is shown and the importance in taking into account the temperature effect on the equilibrium data is demonstrated. 29 refs., 6 figs., 1 tab.

  3. Nitrogen Doped Carbon Nanotubes from Organometallic Compounds: A Review

    Directory of Open Access Journals (Sweden)

    Neil J. Coville

    2010-03-01

    Full Text Available Nitrogen doped carbon nanotubes (N-CNTs have become a topic of increased importance in the study of carbonaceous materials. This arises from the physical and chemical properties that are created when N is embedded in a CNT. These properties include modified chemical reactivity and modified conductivity and mechanical properties. A range of methodologies have been devised to synthesize N-CNTs. One of the procedures uses a floating catalyst in which an organometallic complex is decomposed in the gas phase in the presence of a nitrogen containing reactant to give N-CNTs. Most studies have been limited to ferrocene, ring substituted ferrocene and Fe(CO5. This review covers the synthesis (and properties of N-CNTs and other shaped carbon nanomaterials (SCNMs produced using organometallic complexes. It summarizes the effects that physical parameters such as temperature, pressure, gas flow rates, type and concentration of N source etc. have on the N-CNT type, size and yields as well as the nitrogen content incorporated into the tubes that are produced from organometallic complexes. Proposed growth models for N-CNT synthesis are also reported.

  4. Predicting trace organic compound attenuation with spectroscopic parameters in powdered activated carbon processes.

    Science.gov (United States)

    Ziska, Austin D; Park, Minkyu; Anumol, Tarun; Snyder, Shane A

    2016-08-01

    The removal of trace organic compounds (TOrCs) is of growing interest in water research and society. Powdered activated carbon (PAC) has been proven to be an effective method of removal for TOrCs in water, with the degree of effectiveness depending on dosage, contact time, and activated carbon type. In this study, the attenuation of TOrCs in three different secondary wastewater effluents using four PAC materials was studied in order to elucidate the effectiveness and efficacy of PAC for TOrC removal. With the notable exception of hydrochlorothiazide, all 14 TOrC indicators tested in this study exhibited a positive correlation of removal rate with their log Dow values, demonstrating that the main adsorption mechanism was hydrophobic interaction. As a predictive model, the modified Chick-Watson model, often used for the prediction of microorganism inactivation by disinfectants, was applied. The applied model exhibited good predictive power for TOrC attenuation by PAC in wastewater. In addition, surrogate models based upon spectroscopic measurements including UV absorbance at 254 nm and total fluorescence were applied to predict TOrC removal by PAC. The surrogate model was found to provide an excellent prediction of TOrC attenuation for all combinations of water quality and PAC type included in this study. The success of spectrometric parameters as surrogates in predicting TOrC attenuation by PAC are particularly useful because of their potential application in real-time on-line sensor monitoring and process control at full-scale water treatment plants, which could lead to significantly reduced operator response times and PAC operational optimization. PMID:27174829

  5. Tracing organic compounds in aerobically altered methane-derived carbonate pipes (Gulf of Cadiz, SW Iberia)

    Science.gov (United States)

    Merinero, Raúl; Ruiz-Bermejo, Marta; Menor-Salván, César; Lunar, Rosario; Martínez-Frías, Jesús

    2012-07-01

    The primary geochemical process at methane seeps is anaerobic oxidation of methane (AOM), performed by methanotrophic archaea and sulfate-reducing bacteria (SRB). The molecular fingerprints (biomarkers) of these chemosynthetic microorganisms can be preserved in carbonates formed through AOM. However, thermal maturity and aerobic degradation can change the original preserved compounds, making it difficult to establish the relation between AOM and carbonate precipitation. Here we report a study of amino acid and lipid abundances in carbonate matrices of aerobically altered pipes recovered from the seafloor of the Gulf of Cadiz (SW Iberian Peninsula). This area is characterized by a complex tectonic regime that supports numerous cold seeps. Studies so far have not determined whether the precipitation of carbonate pipes in the Gulf of Cadiz is a purely chemical process or whether microbial communities are involved. Samples from this site show signs of exposure to oxygenated waters and of aerobic alteration, such as oxidation of authigenic iron sulfides. In addition, the degradation index, calculated from the relative abundance of preserved amino acids, indicates aerobic degradation of organic matter. Although crocetane was the only lipid identified from methanotrophic archaea, the organic compounds detected (n-alkanes, regular isoprenoids and alcohols) are compatible with an origin from AOM coupled with bacterial sulfate reduction (BSR) and subsequent aerobic degradation. We establish a relation among AOM, BSR and pipe formation in the Gulf of Cadiz through three types of analysis: (1) stable carbon and oxygen isotopic composition of carbonate minerals; (2) carbonate microfabrics; and (3) mineralogical composition. Our results suggest that carbonate pipes may form through a process similar to the precipitation of vast amounts of carbonate pavements often found at cold seeps. Our approach suggests that some organic compound patterns, in combination with additional

  6. Concentration-dependent polyparameter linear free energy relationships to predict organic compound sorption on carbon nanotubes

    OpenAIRE

    Zhao, Qing; YANG Kun; Li, Wei; Xing, Baoshan

    2014-01-01

    Adsorption of organic compounds on carbon nanotubes (CNTs), governed by interactions between molecules and CNTs surfaces, is critical for their fate, transport, bioavailability and toxicity in the environment. Here, we report a promising concentration-dependent polyparameter linear free energy relationships (pp-LFERs) model to describe the compound-CNTs interactions and to predict sorption behavior of chemicals on CNTs in a wide range of concentrations (over five orders of magnitude). The dev...

  7. Covering vertically aligned carbon nanotubes with a multiferroic compound

    KAUST Repository

    Mahajan, Amit

    2014-10-30

    This work highlights the possible use of vertically-aligned multiwall carbon nanotubes (VA-MWCNTs) as bottom electrodes for microelectronics, for example for memory applications. As a proof of concept BiFeO3 (BFO) films were fabricated in-situ deposited on the surface of VA-MWCNTs by RF (radio frequency) magnetron sputtering. For in situ deposition temperature of 400 °C and deposition time up to 2 h, BFO films cover the MWCNTs and no damage occurs either in the film or MWCNTs. In spite of the macroscopic lossy polarization behaviour, the ferroelectric nature, domain structure and switching of these conformal BFO films was verified by piezo force microscopy. G type antiferromagnetic ordering with weak ferromagnetic ordering loop was proved for BFO films on VA-MWCNTs having a coercive field of 700 Oe.

  8. Synthesis of Heteroaromatic Compounds by Oxidative Aromatization Using an Activated Carbon/Molecular Oxygen System

    Directory of Open Access Journals (Sweden)

    Masahiko Hayashi

    2009-08-01

    Full Text Available A variety of heteroaromatic compounds, such as substituted pyridines, pyrazoles, indoles, 2-substituted imidazoles, 2-substituted imidazoles, 2-arylbenzazoles and pyrimidin-2(1H-ones are synthesized by oxidative aromatization using the activated carbon and molecular oxygen system. Mechanistic study focused on the role of activated carbon in the synthesis of 2-arylbenzazoles is also discussed. In the final section, we will disclose the efficient synthesis of substituted 9,10-anthracenes via oxidative aromatization.

  9. Improvement of Water-Repellency Homogeneity by Compound Fluorine-Carbon Sprayed Coating and Silane Treatment

    OpenAIRE

    FUTAMATA, Masami; Gai, Xiaohui; ITOH, Hidenobu; 伊藤, 英信

    2004-01-01

    To improve the water-repellency of materials, a composite coating of fluorine-carbon has been developed in this study. A thermal sprayed coating produced by using a compound fluorine-carbon cored wire exhibits excellent water-repellency. However, the contact angles of water of the coating surface show remarkable scatters since the fluorine is usually difficult to be distributed uniformly on the coating surface. To improve the homogeneity of the water-repellency of the thermal sprayed coating,...

  10. Effect of dead carbon on the 14C dating of the speleothem

    Institute of Scientific and Technical Information of China (English)

    CAI Yanjun; Warren Beck; PENG Zicheng; ZHANG Zhaofeng

    2005-01-01

    Based on the comparison of dating results among high-precision TIMS U-series and AMS 14C as well as the published 14C dating results and their band counting ages (i.e. calendar ages), this paper discusses the effect of dead carbon on the speleothem 14C dating. The result shows that the fraction of incorporated dead carbon during the formation of speleothem varies. The change in the fraction of dead carbon would result in big deviation in the 14C age of the speleothem. It is indispensable to take the dead carbon into consideration when dating the speleothem using the 14C method or studying the atmospheric 14C concentration during the past with the speleothem.

  11. Carbon Nanomaterials Based Electrochemical Sensors/Biosensors for the Sensitive Detection of Pharmaceutical and Biological Compounds.

    Science.gov (United States)

    Adhikari, Bal-Ram; Govindhan, Maduraiveeran; Chen, Aicheng

    2015-01-01

    Electrochemical sensors and biosensors have attracted considerable attention for the sensitive detection of a variety of biological and pharmaceutical compounds. Since the discovery of carbon-based nanomaterials, including carbon nanotubes, C60 and graphene, they have garnered tremendous interest for their potential in the design of high-performance electrochemical sensor platforms due to their exceptional thermal, mechanical, electronic, and catalytic properties. Carbon nanomaterial-based electrochemical sensors have been employed for the detection of various analytes with rapid electron transfer kinetics. This feature article focuses on the recent design and use of carbon nanomaterials, primarily single-walled carbon nanotubes (SWCNTs), reduced graphene oxide (rGO), SWCNTs-rGO, Au nanoparticle-rGO nanocomposites, and buckypaper as sensing materials for the electrochemical detection of some representative biological and pharmaceutical compounds such as methylglyoxal, acetaminophen, valacyclovir, β-nicotinamide adenine dinucleotide hydrate (NADH), and glucose. Furthermore, the electrochemical performance of SWCNTs, rGO, and SWCNT-rGO for the detection of acetaminophen and valacyclovir was comparatively studied, revealing that SWCNT-rGO nanocomposites possess excellent electrocatalytic activity in comparison to individual SWCNT and rGO platforms. The sensitive, reliable and rapid analysis of critical disease biomarkers and globally emerging pharmaceutical compounds at carbon nanomaterials based electrochemical sensor platforms may enable an extensive range of applications in preemptive medical diagnostics. PMID:26404304

  12. Carbon Nanomaterials Based Electrochemical Sensors/Biosensors for the Sensitive Detection of Pharmaceutical and Biological Compounds

    Directory of Open Access Journals (Sweden)

    Bal-Ram Adhikari

    2015-09-01

    Full Text Available Electrochemical sensors and biosensors have attracted considerable attention for the sensitive detection of a variety of biological and pharmaceutical compounds. Since the discovery of carbon-based nanomaterials, including carbon nanotubes, C60 and graphene, they have garnered tremendous interest for their potential in the design of high-performance electrochemical sensor platforms due to their exceptional thermal, mechanical, electronic, and catalytic properties. Carbon nanomaterial-based electrochemical sensors have been employed for the detection of various analytes with rapid electron transfer kinetics. This feature article focuses on the recent design and use of carbon nanomaterials, primarily single-walled carbon nanotubes (SWCNTs, reduced graphene oxide (rGO, SWCNTs-rGO, Au nanoparticle-rGO nanocomposites, and buckypaper as sensing materials for the electrochemical detection of some representative biological and pharmaceutical compounds such as methylglyoxal, acetaminophen, valacyclovir, β-nicotinamide adenine dinucleotide hydrate (NADH, and glucose. Furthermore, the electrochemical performance of SWCNTs, rGO, and SWCNT-rGO for the detection of acetaminophen and valacyclovir was comparatively studied, revealing that SWCNT-rGO nanocomposites possess excellent electrocatalytic activity in comparison to individual SWCNT and rGO platforms. The sensitive, reliable and rapid analysis of critical disease biomarkers and globally emerging pharmaceutical compounds at carbon nanomaterials based electrochemical sensor platforms may enable an extensive range of applications in preemptive medical diagnostics.

  13. Gas-phase noncovalent functionalization of carbon nanotubes with a Ni(II) tetraaza[14]annulene complex

    International Nuclear Information System (INIS)

    The noncovalent functionalization of carbon nanotubes (CNTs) with aromatic polyazamacrocyclic compounds, based on π–π-interactions, keeps the intrinsic electronic structure of CNTs totally intact and allows for combining unique properties of the two interacting components. In addition to porphyrins and phthalocyanines, there are other, simpler compounds exhibiting similar properties, potentially useful for photovoltaic, catalytic and electrochemical applications: for example, tetraaza[14]annulenes. Many of them are highly thermally stable, which makes it possible to employ physical vapor deposition for the preparation of macrocycle–nanotube hybrids. One of such compounds is Ni(II) complex of 5,7,12,14-tetramethyldibenzo-1,4,8,11-tetraazacyclotetradeca-3,5,7,10,12, 14-hexaene (also called Ni(II)-tetramethyldibenzotetraaza[14]annulene, or NiTMTAA for simplicity). In the present work, we attempted the noncovalent functionalization of both single-walled and multi-walled CNTs with NiTMTAA in the gas phase at two selected temperatures of 220 and 270 °C, which does not require the use of organic solvents and therefore can be considered as ecologically friendly. The nanohybrids obtained were characterized by means of scanning and transmission electron microscopy, energy dispersive X-ray, Fourier-transform infrared and Raman spectroscopy, as well as thermogravimetric analysis. An additional insight into the structure of adsorption complexes of NiTMTAA on CNTs was provided from density functional theory and molecular mechanics calculations.

  14. Effect of industrial fuel combustion on the carbon-14 level of atmospheric CO2

    International Nuclear Information System (INIS)

    As was previously noticed in 1953 by SUESS, the radiocarbon content of atmospheric CO2 was slightly lower in the 20th century (before the increase in the carbon-14 level due to the addition of artificial 14C) than at the time before the beginning of the industrial revolution in the 19th century. An exact knowledge of the magnitude of this effect is of interest in connection with the question of the rate of isotope exchange between atmospheric CO2 and the bicarbonates of the oceans. However, the radiocarbon level in the CO2 of the atmosphere is also subject to natural fluctuations caused by a variable cosmic-ray production rate of carbon-14. To investigate this the authors have cross-correlated sunspot numbers (as indicators of cosmic-ray activity) with the carbon-14 level in wood, and have detected a significant coherence between the two time series. The observed coherence permits an extrapolation of the natural carbon-14 values beyond the time of the beginning of artificial combustion of fossil fuel, around 1880. The results show that the observed small decrease in the carbon-14 level is somewhat affected by the increase of the production rate of carbon-14, as a consequence of relatively low solar activity during the preceding decades. The effect of industrial fuel combustion upon the carbon-14 level of the atmosphere can then be estimated for the Northern Hemisphere to be in the vicinity of -3%. (author)

  15. Laboratory Experiments to Evaluate Matrix Diffusion of Dissolved Organic Carbon Carbon-14 in Southern Nevada Fractured-rock Aquifers

    Energy Technology Data Exchange (ETDEWEB)

    Hershey, Ronald L. [Nevada University, Reno, NV (United States). Desert Research Institute; Fereday, Wyatt [Nevada University, Reno, NV (United States). Desert Research Institute

    2016-05-01

    Dissolved inorganic carbon (DIC) carbon-14 (14C) is used to estimate groundwater ages by comparing the DIC 14C content in groundwater in the recharge area to the DIC 14C content in the downgradient sampling point. However, because of chemical reactions and physical processes between groundwater and aquifer rocks, the amount of DIC 14C in groundwater can change and result in 14C loss that is not because of radioactive decay. This loss of DIC 14C results in groundwater ages that are older than the actual groundwater ages. Alternatively, dissolved organic carbon (DOC) 14C in groundwater does not react chemically with aquifer rocks, so DOC 14C ages are generally younger than DIC 14C ages. In addition to chemical reactions, 14C ages may also be altered by the physical process of matrix diffusion. The net effect of a continuous loss of 14C to the aquifer matrix by matrix diffusion and then radioactive decay is that groundwater appears to be older than it actually is. Laboratory experiments were conducted to measure matrix diffusion coefficients for DOC 14C in volcanic and carbonate aquifer rocks from southern Nevada. Experiments were conducted using bromide (Br-) as a conservative tracer and 14C-labeled trimesic acid (TMA) as a surrogate for groundwater DOC. Outcrop samples from six volcanic aquifers and five carbonate aquifers in southern Nevada were used. The average DOC 14C matrix diffusion coefficient for volcanic rocks was 2.9 x 10-7 cm2/s, whereas the average for carbonate rocks was approximately the same at 1.7 x 10-7 cm2/s. The average Br- matrix diffusion coefficient for volcanic rocks was 10.4 x 10-7 cm2/s, whereas the average for carbonate rocks was less at 6.5 x 10-7 cm2/s. Carbonate rocks exhibited greater variability in

  16. Study of carbon-isotope exchange reactions between potassium cyanide and some carbonates, and their use for obtaining C14-labelled potassium cyanide

    International Nuclear Information System (INIS)

    The authors examine the results of a study on the isotope exchange of potassium cyanide with compounds differing greatly from it both in composition and structure, such as carbonates of alkaline and alkali-earth metals. The carbon-isotope exchange reaction in the KC12N-BaC14O3 system was studied at 600-800oC. The ratio between the components of this system and those given below agreed with the equimolecular ratio. The authors show that at high temperatures complete exchange between these compounds can be secured. The exchange reaction begins when the cyanide melt is formed; later it occurs between the liquid and the solid phases, and its speed increases with temperature; at 800oC it is completed in 2 h. With carbonates of alkali metals the exchange reaction occurs in the melt and is completed at lower temperatures. The authors obtained cyanide-labelled potassium by the following method : (1) The isotope exchange reaction KC12N-BaC14O3 is produced at 800oC in 2 h. (2) The mixture KCN+BaCO3 is separated by extracting the KCN with liquid ammonia in a circulating extractor. By exchanging the equimolecular quantities KCN and BaCO3, potassium cyanide is obtained with a chemical yield of more than 90% and a basic-substance content of 96-97%. By using BaCO3 with a high specific activity (60-70 mc/g), a KCN specific activity of over 80 mc/g may be obtained. The barium carbonate depleted of isotope C14 regenerates after the ammonia extraction without appreciable loss. (author)

  17. Emissions to air in Sweden: carbon dioxide, methane, nitrous oxide, nitrogen oxides, carbon monoxide, volatile organic compounds and sulphur dioxide 1990-2000

    International Nuclear Information System (INIS)

    Greenhouse gases - Carbon dioxide from combustion and motor fuels, Methane and Laughing gas from agriculture Carbon dioxide (CO2) emissions in Sweden amounted to 56 million tonnes in 2000, which is minor decrease since 1990. Combustion of fossil fuels and the use of fuels in vehicles are the major sources of CO2 emissions. Methane is the second most important greenhouse gas, and it is emitted when bacteria degrade organic matter. In Sweden the main source is enteric fermentation from cattle. The emissions of methane were 324 000 tonnes 1990. In 2000 the emissions amounted to 280 000 tonnes, or a 14 per cent decrease. The third greenhouse gas, N2O is mostly emitted from agriculture. N2O emissions have fallen somewhat. Total emissions of sulphur dioxide (SO2) and nitrogen oxides (NOx, counted as NO2) in Sweden were 58,000 and 247,000 tonnes respectively in 2000. International air and maritime traffic is not included. The major source of SO2 emissions is combustion of fossil fuels. Road traffic is the major source of NOX emissions. Emissions of carbon monoxide (CO) and non-methane volatile organic compounds (NMVOCs) are also presented in this report. The main source of CO is road traffic, while NMVOCs come from household combustion and road traffic. Emission trends for fluoride carbon greenhouse gases HFCs, PFCs and SF6 are also presented. These gases mainly emit from refrigerators, freezing and air conditioning equipment (e.g. in cars and buildings) and from heat pumps

  18. Characterization of carbon, sulfur and volatile compounds in nuclear fuel U3SI2-AL

    International Nuclear Information System (INIS)

    The scope of this work is to describe the characterization of Carbon, Sulfur and Volatile Compounds in nuclear fuel U3Si2-Al used in a research pool type reactor with 5 KW power capacities, located in Sao Paulo, Brazil. This reactor produces a large range of radioisotopes for radiopharmaceutical needed in Brazil nuclear medicine. The fabrication of the fuel U3Si2-Al plate is the key of the whole assembly production and its quality directly affects the safety and reliability of the fuel assembly performance. For this reason, it is very necessary to analyze the Carbon, Sulfur and Volatile Compounds to avoid damage in the fuel plate. The Carbon and Sulfur are characterized by the method of radio frequency furnace gas extraction system coupled with infrared cell detector. The Volatile Compounds are characterized by the method of heat gas extraction coupled with gravimetric technique. These methods are recommended by American Society for Testing Materials ASTM for nuclear materials. The average carbon and sulfur analyzed are 30 μg/g and 3 μg/g, respectively. The average for Volatile Compounds is 40 μg/g. These results represent satisfactory performance of the fuel inside the nuclear reactor. A statistical laboratory program has been set to validate the data generated in the nuclear fuel material to specify any agreement with the recommended ASTM methods. (author)

  19. Modelling accidental releases of carbon 14 in the environment: application as an excel spreadsheet

    International Nuclear Information System (INIS)

    An application as an Excel spreadsheet of the simplified modelling approach of carbon 14 transfer in the environment developed by Tamponnet (2002) is presented. Based on the use of growth models of biological systems (plants, animals, etc.), the one-pool model (organic carbon) that was developed estimates the concentration of carbon 14 within the different compartments of the food chain and in fine the dose to man by ingestion in the case of a chronic or accidental release of carbon 14 in a river or the atmosphere. Data and knowledge have been implemented on Excel using the object-oriented programming language VisualBasic (Microsoft Visual Basic 6.0). The structure of the conceptual model and the Excel sheet are first briefly exposed. A numerical application of the model under a scenario of an accidental release of carbon 14 in the atmosphere is then presented. Simulation results and perspectives are discussed. (author)

  20. Synthesis of methyl [(chloro-2 ethyl)-3 nitroso-3 Ureido]-3 Didesoxy-2,3 α-D-Arabino-hexopyrannoside labelled with carbon-14 or carbon-13 (CY 233 - SR 90008)

    International Nuclear Information System (INIS)

    CY 233 (Ecomustine or SR 90098) is a new antitumour nitrosourea: it is characterized by a 2-chloroethylnitrosourea substituent on a dideoxycarbohydrate. It has been labelled with 14C on a) the carbonyl group of the urea in four stages starting with 14COCl2, b) the second carbon of the chloroethyl group in four stages starting with [14C] ethanolamine, and c) on the methyl group on the anomeric centre of the carbohydrate in three stages starting with 14CH3OH. The final position was also labelled with 13C starting with 13CH3OH. These differently labelled compounds are suitable for mechanistic studies of antitumour activity. (author)

  1. Selective adsorption for removal of nitrogen compounds from hydrocarbon streams over carbon-based adsorbents

    Science.gov (United States)

    Almarri, Masoud S.

    The ultimate goal of this thesis is to develop a fundamental understanding of the role of surface oxygen functional groups on carbon-based adsorbents in the adsorption of nitrogen compounds that are known to be present in liquid fuels. N2 adsorption was used to characterize pore structures. The surface chemical properties of the adsorbents were characterized by X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption (TPD) techniques with a mass spectrometer to identify and quantify the type and concentration of oxygen functional groups on the basis of CO2 and CO evolution profiles. It was found that although surface area and pore size distribution are important for the adsorption process, they are not primary factors in the adsorption of nitrogen compounds. On the other hand, both the type and concentration of surface oxygen-containing functional groups play an important role in determining adsorptive denitrogenation performance. Higher concentrations of the oxygen functional groups on the adsorbents resulted in a higher adsorption capacity for the nitrogen compounds. A fundamental insight was gained into the contributions of different oxygen functional groups by analyzing the changes in the monolayer maximum adsorption capacity, qm, and the adsorption constant, K, for nitrogen compounds on different activated carbons. Acidic functional groups such as carboxylic acids and carboxylic anhydrides appear to contribute more to the adsorption of quinoline, while the basic oxygen functional groups such as carbonyls and quinones enhance the adsorption of indole. Despite the high number of publications on the adsorptive desulfurization of liquid hydrocarbon fuels, these studies did not consider the presence of coexisting nitrogen compounds. It is well-known that, to achieve ultraclean diesel fuel, sulfur must be reduced to a very low level, where the concentrations of nitrogen and sulfur compounds are comparable. The adsorptive denitrogenation and

  2. 14 C labelled compound Laboratory of Radiochemical Research and Production Department in IFIN-HH. Forty years of experience

    International Nuclear Information System (INIS)

    The first experiments with 14 C in Romania took place in the Institute of Atomic Physics (IFA) in Bucharest. The laboratory for C-14 labelled compounds, with its current structure was conceived by IFA in co-operation with GEC and AERE - England, and designed by IFA and I.P. Carpati. It was built between 1975-1977. The way it was conceived makes it the only laboratory in Romania which can offer various specialized services to interested organizations. The laboratory is able to develop the following types of activity: - primary processing of row materials with 14 C; - chemical syntheses and biosyntheses of labelled organic and inorganic compounds; - production of 14 C tracers; - specific chemical analyses involving 14 C processing. Till now among the most important results the following could be mentioned: over 60 C-14 labelled organic and inorganic compounds; over 20 publications; about 50 certified products and technologies; delivery of C-14 labelled products all over the country, in over 20 research institutes, hospitals and universities; - experiments with tracers for food industry, agriculture and livestock farms; - solutions with C-14 - calibration standards for internal use. Presently the Laboratory is conducting in cooperation with the Institute for Nuclear Research, Pitesti works for recovering of 14 C from gaseous effluents of CANDU-600 Reactor of NNP-Cernavoda. Also, works are done concerning the synthesis with 13 C and 14 C of miscellaneous organic compounds, i.e., 3N-[1-13 C] Capronylphenylthiourea, trans-derma pharmaceutic systems and N -[1 - 13 C,T] pentadecyl pyridinium bromide (both doubly labelled with T and 14 C with high specific activities at known positions); the last two compounds was certified too. The path ways for labelling and analyses are in agreement with the international techniques adopted in this field. (authors)

  3. Synthesis of carbon nanotubes by catalytic pyrolysis method with Feitknecht compound as precursor of NiZnAl catalyst

    Institute of Scientific and Technical Information of China (English)

    Yan Xiaoqi; Liu Quanrun; Zhang Songlin; Zhang Kun; Chen Jiuling; Li Yongdan

    2004-01-01

    Carbon nanotubes are synthesized by catalytic pyrolysis method with a kind of new type catalyst--nickel-zinc-alumina catalyst prepared from Feitknecht compound. Tubular carbon nanotubes, bamboo-shaped carbon naotubes, herringbone carbon nanotubues and branched carbon nanotubes are all found formed at moderate temperature. It is important for the formation of quasi-liquid state of the metal nanoparticles at the tip of carbon naotubes during the growth of carbon nanotubes to lead to different kinds of carbon nanotubes. It is likely that the addition of zinc make the activity of nickel catalyst after calcinations and reduction changed strangely.

  4. Stable Isotopic Evidence for a Pedogenic Origin of Carbonates in Trench 14 near Yucca Mountain, Nevada.

    Science.gov (United States)

    Quade, J; Cerling, T E

    1990-12-14

    Layered carbonate and silica encrust fault fractures exposed in Trench 14 near Yucca Mountain, site of the proposed high-level nuclear waste repository in southern Nevada. Comparison of the stable carbon and oxygen isotopic compositions of the fracture carbonates with those of modern soil carbonates in the area shows that the fracture carbonates are pedogenic in origin and that they likely formed in the presence of vegetation and rainfall typical of a glacial climate. Their isotopic composition differs markedly from that of carbonate associated with nearby springs. The regional water table therefore remained below the level of Trench 14 during the time that the carbonates and silica precipitated, a period probably covering parts of at least the last 300,000 years. PMID:17818282

  5. Synthesis of the monosodium salt of carbon-14 labeled paclitaxel (Taxol) 2`-ethyl carbonate 7-phosphonooxymethyl ether, a potential prodrug of paclitaxel

    Energy Technology Data Exchange (ETDEWEB)

    Dischino, D.D.; Shuhui Chen; Golik, Jerzy; Walker, D.W.; Wong, H.S.L. [Bristol-Myers Squibb Co., Richard L. Gelb Center for Research and Development, Wallingford, CT (United States)

    1997-02-01

    The monosodium salt of carbon-14 labeled paclitaxel (Taxol) [N3`-{sup 14}COPh] 2`-ethyl carbonate 7-phosphonooymethyl ether, was prepared from C-14 labeled paclitaxel [N3`-{sup 14}COPh] in 5 steps. The radiochemical purity of the final product was greater than 99% and the specific activity was 25 {mu}Ci/mg. (author).

  6. Carbon transfer in soil - plant system. Molecular labelling utilization for determining rhizosphere compounds

    International Nuclear Information System (INIS)

    The growing up of the bacteria developing in the rhizosphere of plants is dependent on the compounds exudation by plant roots. Even the bacterial genetics use has permitted to identify diverse functions involved in the process of the rhizosphere colonisation ( mobility, heterotrophic bacteria, growing rate, antibiotics production), there is a big delay in vegetal partners. To decrease this delay we tried to characterize the interactions between a plant model, Arabidopsis thaliana and the rhizosphere bacteria. An experimental device has been conceived for measuring the transfer of carbon issued from the photosynthesis to roots and soil. The exudation by roots has been studied. The analysis of rhizospheric compounds in situ pose some methodological problems, especially, the rhizospheric compounds must be extracted from the soil matrix. we suggest an analysis method of rhizospheric compound and of their dynamics. (F.M.)

  7. Adsorption studies of recalcitrant compounds of molasses spentwash on activated carbons.

    Science.gov (United States)

    Figaro, S; Louisy-Louis, S; Lambert, J; Ehrhardt, J-J; Ouensanga, A; Gaspard, S

    2006-10-01

    Due to high levels of residual chemical oxygen demand (COD) in the effluent of molasses spentwash (MSW) after anaerobic treatment, acceptable COD levels for discharge cannot be achieved without some form of post-treatment. In this study, the particulate composition of molasses spentwash after anaerobic digestion (MSWD), is characterised as to its particle size distribution, using micro- and ultrafiltration and three activated carbons are characterised as to their ability to reduce significantly the COD of MSWD effluent. The activated carbons tested as adsorbent, were characterised by XPS spectroscopy, elemental analysis, surface area, pore size distribution, and acid-base titration using the Boehm's method. Adsorption of phenol, used here as a reference compound, and of some organic compounds contained in MSWD (gallic acid, tannic acid, and melanoidin, respectively), was studied. It was clearly demonstrated that an activated carbon with a significant distribution of both micropores and mesopores and a significant amount of macropores that are assumed to act as conduits providing access to micro- and mesopores, have a good adsorption efficiency for compounds such as tannic acid and melanoidins. It is a good adsorbent for melanoidin and coloured compounds of MSWD, which represents a large source of the aqueous pollution in sugar cane industries. PMID:16987542

  8. Synthesis of δ-aminolevulic acid. Application to the introduction of carbon-14 and of tritium

    International Nuclear Information System (INIS)

    Several new syntheses of δ aminolevulic acid (δ A.L.A.) have been studied. 14C-4 δ - aminolevulic acid has been obtained from 14C allylacetic carboxylic acid with a yield of 30 per cent with respect to barium carbonate and with a specific activity of 32 mCi/mM. The 14C-1 or 14C-2 δ-A.L.A. has been prepared from the 14C-1 or 14C-2 acetate with a yield of 55 per cent with respect to the acetate. Finally the tritiated δ-A.L.A. has been obtained for the first time by tritiation of ethyl phthalimidodehydrolevulate. (author)

  9. Radiocarbon 14C differentiation of sparkling and carbonated wines

    International Nuclear Information System (INIS)

    Specific 14C-activities, percent of modern 14C-activity, and calculated percent of fermentation CO2 are presented for CO2 contained in commercial sparkling wines, labeled as champagne or produced by the bulk (charmat) process. These data are given for the production years 1976-1982. The survey encompassed effervescent wines produced in Spain, Italy, West Germany, California, and New York. Addition of synthetic CO2 to approximately 40 samples represented as sparkling wines was indicated by low 14C-activities of CO2 in these wines. Data for 14C-activity were also presented for the ethanol distilled from sparkling wines for the years 1977-1980. In all cases, the 14C-activity of ethanol was appropriate to the year of vintage

  10. Hydrogen isotopic compositions of organic compounds in plants reflect the plant's carbon metabolism

    Science.gov (United States)

    Cormier, M. A.; Kahmen, A.; Werner, R. A.

    2015-12-01

    The main factors controlling δ2H of plant organic compounds are generally assumed to be the plant's source water and the evaporative deuterium enrichment of leaf water. Hydrogen isotope analyses of plant compounds from sediments or tree rings are therefore mainly applied to assess hydrological conditions at different spatial and temporal scales. However, the biochemical hydrogen isotope fractionation occurring during biosynthesis of plant organic compounds (ɛbio) also accounts for a large part of the variability observed in the δ2H values. Nevertheless, only few studies have directly addressed the physiological basis of this variability and even fewer studies have thus explored possible applications of hydrogen isotope variability in plant organic compounds for plant physiological research. Here we show two datasets indicating that the plant's carbon metabolism can have a substantial influence on δ2H values of n-alkanes and cellulose. First, we performed a controlled experiment where we forced plants into heterotrophic and autotrophic C-metabolism by growing them under four different light treatments. Second, we assessed the δ2H values of different parasitic heterotrophic plants and their autotrophic host plants. Our two datasets show a systematic shift in ɛbio of up to 80 ‰ depending on the plant's carbon metabolism (heterotrophic or autotrophic). Differences in n-alkane and cellulose δ2H values in plants with autotrophic vs. heterotrophic metabolisms can be explained by different NADPH pools that are used by the plants to build their compounds either with assimilates that originate directly from photosynthesis or from stored carbohydrates. Our results have significant implications for the calibration and interpretation of geological records. More importantly, as the δ2H values reflect the plant's carbon metabolism involved during the tissue formation, our findings highlight the potential of δ2H values as new tool for studying plant and ecosystem carbon

  11. Correlation and prediction of adsorption capacity and affinity of aromatic compounds on carbon nanotubes.

    Science.gov (United States)

    Wu, Wenhao; Yang, Kun; Chen, Wei; Wang, Wendi; Zhang, Jie; Lin, Daohui; Xing, Baoshan

    2016-01-01

    Adsorption of 22 nonpolar and polar aromatic compounds on 10 carbon nanotubes (CNTs) with various diameters, lengths and surface oxygen-containing group contents was investigated to develop predictive correlations for adsorption, using the isotherm fitting of Polanyi theory-based Dubinin-Ashtakhov (DA) model. Adsorption capacity of aromatic compounds on CNTs is negatively correlated with melting points of aromatic compounds, and surface oxygen-containing group contents and surface area ratios of mesopores to total pores of CNTs, but positively correlated with total surface area of CNTs. Adsorption affinity is positively correlated with solvatochromic parameters of aromatic compounds, independent of tube lengths and surface oxygen-containing group contents of CNTs, but negatively correlated with surface area ratios of mesopores to total pores of CNTs. The correlations of adsorption capacity and adsorption affinity with properties of both aromatic compounds and CNTs clearly have physical significance, can be used successfully with DA model to predict adsorption of aromatic compounds on CNTs from the well-known physiochemical properties of aromatic compounds (i.e., solvatochromic parameters, melting points) and CNTs (i.e., surface area and total acidic group contents), and thus can facilitate the environmental application of CNTs as sorbents and environmental risk assessment of both aromatic contaminants and CNTs. PMID:26521219

  12. Possibility of diacetyl and related compounds as the 4-carbon compound necessary for the formation of riboflavin in Ashbya gossypii.

    Science.gov (United States)

    Nakajima, K; Mitsuda, H

    1984-01-01

    The effects of various compounds (0.5%) involved in the butanediol and the glycolytic pathways on riboflavin formation in whole cells of Ashbya gossypii at rest were examined. The addition of acetate, glycerol and diacetyl inhibited riboflavin formation, while the addition of acetoin had no effect on it, and the addition of ethanol, 2,3-butanediol, pyruvic acid and glucose accelerated it. The relation of diacetyl and acetoin to riboflavin formation during resting cell incubation in the presence of 0.5% ethanol and various concentrations of 2,3-butanediol was examined. The results quantitatively revealed a precursor-product relation between riboflavin formation and the formation of diacetyl and acetoin. The results obtained provide evidence that a high flavinogenic agent, ethanol, was converted to acetaldehyde, pyruvic acid, acetoin and diacetyl in this order, that a week flavinogenic agent, 2,3-butanediol, was transferred to diacetyl through acetoin, and that the diacetyl produced can be utilized as the 4-carbon compound for riboflavin formation in the flavinogenic mold, Ashbya gossypii. It remains obscure whether diacetyl is enzymatically involved in riboflavin formation. PMID:6534171

  13. The Path of Carbon in Photosynthesis XVII. Phosphorus Compounds as Intermediates in Photosynthesis

    Science.gov (United States)

    Buchanan, J. G.; Bassham, J. A.; Benson, A. A.; Bradley, D. F.; Calvin, M.; Daus, L. L.; Goodman, M.; Hayes, P. M.; Lynch, V. H.; Norris, L. T.; Wilson, A. T.

    1952-07-08

    Studies of carbon dioxide fixation in green plants using the C{sup 14} isotope have shown that in very short times phosphoglyceric acid contains most of the radioactivity. The tracer is present almost entirely in the carboxyl group. The importance of organic phosphates in the subsequent metabolism of phosphoglyceric acid can be seen from the accompanying photographs.

  14. Catalytic Conversion of Carbon-Containing Compounds into Valuable Chemicals and Fuels

    Science.gov (United States)

    Cheng, Zhuo

    Conversion of carbon-containing compounds, especially C1 compounds such as carbon dioxide and methane, to valuable chemicals and fuels will hopefully address concerns over decreasing supplies of fossil fuels and mitigate the eects of greenhouse gas emissions on global climate change. Many challenges, however, remain to be addressed before these technologies may be adopted on an industrial scale. Chiefly, catalysts must be developed to activate carbon-containing compounds from their thermodynamically stable ground states, using hydrogen, electrons, or heat as energy sources. We chose as model catalytic systems: 1) Metathesis of ethene and 2-butene; 2) Methane dehydrogenation and carbon dioxide hydrogenation. We developed three computational methodologies to study these processes across a range of length and time scales. First, we investigated how electronic structure affects the properties and reactivity of these catalyst systems; by computing the partial electronic density of states, electronic localization function, and excess spin density, we showed how redox supports, such as ceria, promote electron transfer reactions. We applied this to the studies of methane activation and carbon dioxide activation. Second, we developed a non-equilibrium thermodynamics approach to calculate energies of activation at nite temperatures, based on the Bronsted-Evans-Polanyi principle and the Nudged Elastic Band method. Third, we developed an approach to numerically compute heat capacities and other thermodynamic properties on extended catalytic systems that are comparable in accuracy and precision to methods that have been well-developed for gas-phase molecules. We applied these to the studies of metathesis propagation and carbon dioxide hydrogenation. We gained mechanistic, thermodynamic, and kinetic insight into the elementary steps that comprise larger reaction networks of interest to the broader catalysis community. Ultimately, these theoretical and computational predictions

  15. Electrically Conductive Compounds of Polycarbonate, Liquid Crystalline Polymer, and Multiwalled Carbon Nanotubes

    OpenAIRE

    Penwisa Pisitsak; Rathanawan Magaraphan; Sadhan C. Jana

    2012-01-01

    A thermotropic liquid crystalline polymer (LCP) was blended with polycarbonate (PC) and multiwalled carbon nanotube (CNT) with the goal of improving electrical conductivity and mechanical properties over PC. The LCP was anticipated to produce fibrillar domains in PC and help improve the mechanical properties. The study was carried out using two grades of LCP—Vectra A950 (VA950) and Vectra V400P (V400P). The compounds contained 20 wt% LCP and 0.5 to 15 wt% CNT. The compounds were prepared by m...

  16. Modelling the behaviour of carbon 14 released by nuclear power plants in rivers

    International Nuclear Information System (INIS)

    Under routine operation, French nuclear power plants of the PWR type release small amounts of carbon 14 in the environment either as airborne or liquid effluents. With the improvement of nuclear waste management, resulting in a significant reduction in corrosion products discharges, carbon 14 currently stands out as one of the main contributor to the individual dose to the public. Besides, with the decrease in military weapon tests fallout levels, nuclear reactors liquid releases are becoming the dominant artificial source of carbon 14 in rivers, downstream of power plants. To properly assess the fate of carbon 14 in rivers and to calculate individual doses to critical groups, a time-dependent food chain model was developed which considered the migration of carbon 14 in rivers and the transfer to terrestrial environments through irrigation with river water. Processes included in the model are: (1) dilution and equilibrium between the different forms of dissolved inorganic carbon in water, (2) exchange of carbon dioxide between water and atmosphere, (3) transfer to aquatic organisms, (4) transfer of irrigation water in the soil profile, (5) loss from the soil through volatilisation, (6) incorporation in plants by way of photosynthesis (7) transfer to livestock. This model is implemented on the Loire river and the modelling results are compared with the data obtained in radioecological surveys. These elements are then used to calculate doses to humans and non-human biota and assess the contribution from natural and industrial origins. (author)

  17. Results of interagency effort to determine carbon-14 source term in low-level radioactive waste

    International Nuclear Information System (INIS)

    A preliminary estimate of the risks from the shallow land disposal of low-level radioactive wastes by EPA in 1984-1985 indicated that Carbon-14 caused virtually all of the risk and that these risks were relatively high. Therefore, an informal interagency group, which included the US Department of Energy, US Geological Survey, US Nuclear Regulatory Commission, and US Environmental Protection Agency, formed in 1985 to obtain up-to-date information on the activity and chemical form of Carbon-14 in the different types of LLW and how Carbon-14 behaves after disposal. The EPA acted as a focal point for collating the information collected by all of the Agencies and will publish a report in Fall 1986 on the results of the Carbon-14 data collection effort. Of particular importance, the study showed that Carbon-14 activity in LLW was overestimated approximately 2000%. This paper summarizes results of the Carbon-14 data collection effort. 40 references, 1 figure, 3 tables

  18. Asphalt in carbon-14-dated archaeological samples from Terqa, Syria

    International Nuclear Information System (INIS)

    The results are reported of an organic geochemical study to verify contamination in 14C dated archaeological samples, which could account for much older apparent ages than expected. The data indicate that ancient asphalt must be the source of contamination, showing that caution should be exercised, in interpreting 14C dates of archaeological samples from areas containing asphalt or other fossil fuel deposits. (U.K.)

  19. Behavior of environmental carbon-14 and tritium in Japan

    International Nuclear Information System (INIS)

    The 14C activity in plants began to rise appreciably above normal in 1957, and the level rose almost linearly with the rate of 7% per year to the level in 1959. Steep increase of the level to a peak in 1963, between 85% and 90% above normal, shows the effect of large scale nuclear explosions through the end of 1962. Liquid scintillation counting was used as a sensitive assay method of 14C and 3H. For 14C determination, the naturally incorporated 14C into alcohol and essential oils (thymol, menthol and lemongrass oil) and used, and water samples were used for 3H measurement. The total amount 65 x 1027 of 14C atoms has been produced in nuclear tests, and this amount is about 3% of the total amount of 14C in nature. The 3H concentration in rivers, streams and ponds decreased exponentially from 600 pCi/l in 1967 to 150 pCi/l in 1972, with the half life of 2.5yr. The difference of the 3H concentration in surface water according to the sampling locations implies geographical and meteorological variations in fallout 3H level. It is said conclusively that environmental waters in Japan have not been influenced by the discharge effluent of the facilities with regard to tritium contamination and that tritium content in precipitation still play an important role in reflecting annual variation of tritium concentration to surface waters. (J.P.N.)

  20. Carbon compound used in hydrogen storage; Compuesto de carbon utilizado en almacenamiento de hidrogeno

    Energy Technology Data Exchange (ETDEWEB)

    Iturbe G, J.L.; Lopez M, B.E. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2004-07-01

    In the present work it is studied the activated carbon of mineral origin for the sorption of hydrogen. The carbon decreased of particle size by means of the one alloyed mechanical. The time of mill was of 10 hours. The characterization one carries out by scanning electron microscopy and X-ray diffraction. The hydrogen sipped in the carbon material it was determined using the Thermal gravimetric method (TGA). The conditions of hydrogenation went at 10 atm of pressure and ambient temperature during 18 hours. They were also carried out absorption/desorption cycles of hydrogen in the same one system of thermal gravimetric analysis. The results showed percentages of sorption of 2% approximately in the cycles carried out in the system TGA and of 4.5% in weight of hydrogen at pressure of 10 atmospheres and ambient temperature during 18 hours. (Author)

  1. Atmospheric nuclear weapons test history narrated by carbon-14 in human teeth

    International Nuclear Information System (INIS)

    The atmospheric testing of nuclear weapons since 1945 caused a significant increase in the concentration of atmospheric 14C. The 14C concentration in plants that assimilate 14C directly by photosynthesis reflects the atmospheric 14C concentration. Carbon-14 is then transferred into the human body through the food chain. Based on animal experiments, the collagen in human teeth is metabolically inert after its formation. This implies that the collagen of each tooth retains the 14C concentration which reflects the 14C concentration in the blood at the time collagen metabolism ceased. The distribution of the 14C concentration in the collagen of teeth from subjects of various ages would follow a pattern similar to that shown by soft tissues. In this paper the authors elucidate the relationship between the number of nuclear weapon tests and the distribution of 14C concentration in teeth

  2. Carbon functionalized mesoporous silica-based gas sensors for indoor volatile organic compounds.

    Science.gov (United States)

    Liu, Yupu; Chen, Junchen; Li, Wei; Shen, Dengke; Zhao, Yujuan; Pal, Manas; Yu, Haijun; Tu, Bo; Zhao, Dongyuan

    2016-09-01

    Indoor organic gaseous pollution is a global health problem, which seriously threats the health and life of human all over the world. Hence, it is important to fabricate new sensing materials with high sensitivity and efficiency for indoor volatile organic compounds. In this study, a series of ordered mesoporous silica-based nanocomposites with uniform carbon coatings on the internal surface of silica mesopore channels were synthesized through a simple template-carbonization strategy. The obtained mesoporous silica-carbon nanocomposites not only possess ordered mesostructures, high surface areas (up to ∼759m(2)g(-1)), large and tunable pore sizes (2.6-10.2nm), but also have the improved hydrophobicity and anti-interference capability to environmental humidity. The sensing performances of the mesoporous silica-carbon nanocomposites to volatile organic compounds, such as ethylbenzene, methylbenzene, benzene, methanol, acetone, formaldehyde, dichloromethane and tetrahydrofuran, were systematically investigated. The relationships between the sensing performances and their properties, including mesostructures, surface areas, pore sizes, carbon contents and surface hydrophilic/hydrophobic interactions, have been achieved. The mesoporous silica-carbon nanocomposites with hexagonal mesostructure exhibit outstanding performance at room temperature to benzene and acetone with high responses, short response (2-3s) and recovery (16-19s) time, strong anti-interference to environmental humidity, and long-term stability (less than ∼5% loss of the frequency shifts after 42days). Therefore, the obtained mesoporous silica-carbon nanocomposites have a hopeful prospect in the field of environmental air quality monitoring. PMID:27240244

  3. Carbon 14 absorption and translocation in sugar cane

    International Nuclear Information System (INIS)

    Plant-cane stools were labelled with sup(14) CO sub(2), in the field, at Goiana-PE, Brazil, when 3, 7 and 11 months old. Each stool was enclosed in a chamber with sup(14) CO sub(2) for 90 minutes. The sub(14) C photosynthetic were measured in leaves, stalks, roots and soil 24 hours after labelling. Roots were divided into alive and dead and soil into rhizosphere and outer soil. At the end of the labelling period at 3, 7 and 11 months, 2, 19 and 1% of the initial sup(14) CO sub(2) were recovered in the plant and the soil. The low recovery of sub(14) C at 3 months could be attribute to losses by respiration and lack of sampling of the top growing point. The low CO sub(2) fixation and losses at first sampling in the 7 month old labelling were attributed to low light intensity during the day of labelling. Most of the recovered sub(14) C (>80%) was founded in the leaves but all plant parts received labelled photosynthetic. At 3 months, most of the sub(14) C translocated from the leaves went to the living roots (83%); at 7 and 11 months it went to the stalks (69 and 66%). While the roots received less than 2%. Root masses did not vary consistently along the plant cycle and dead root masses were always less than 10% of the total root mass. Radioactivity in the dead roots was always very low. These results suggest that the root system have a low turnover rate after 3 months old. (author)

  4. O-methylation of natural phenolic compounds based on green chemistry using dimethyl carbonate

    Science.gov (United States)

    Prakoso, N. I.; Pangestu, P. H.; Wahyuningsih, T. D.

    2016-02-01

    The alkyl aryl ether compounds, of which methyl eugenol and veratraldehyde are the simplest intermediates can be synthesized by reacting eugenol and vanillin with the green reagent dimethyl carbonate (DMC). The reaction was carried out under mild of temperature and pressure. Excellent yields and selective products were obtained (95-96%) after a few hours. In the end of the reaction, the catalysts (base and Phase Transfer Catalyst) can be recovered and regenerated.

  5. Angle-Dependent Electron Spectroscopy Studies of C60 Compounds and Carbon Nanotubes

    OpenAIRE

    Schiessling, Joachim

    2003-01-01

    Fullerenes have been shown to constitute a prototypical building block for truly nanometer-sized devices and exotic nanounit-based materials, e.g., high-temperature superconductors. This makes the detailed understanding of fullerene electronic states in compounds and at interfaces of primary importance, since the high symmetry of the molecule greatly simplifies the starting point of the analysis. Carbon nanotubes, which combine one macroscopic with two nanoscopic dimensions, are perhaps of e...

  6. Supercritical Carbon Dioxide Extraction of Bioactive Compounds from Ampelopsis grossedentata Stems: Process Optimization and Antioxidant Activity

    OpenAIRE

    Da Sun; Shikang Zhang; Yuefei Wang; Ping Xu; Yuejin Zhu; Le Ying

    2011-01-01

    Supercritical carbon dioxide (SC-CO2) extraction of bioactive compounds including flavonoids and phenolics from Ampelopsis grossedentata stems was carried out. Extraction parameters such as pressure, temperature, dynamic time and modifier, were optimized using an orthogonal array design of L9 (34), and antioxidant activities of the extracts were evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay and ferrous ion chelating (FIC) assay. The best conditions obtained f...

  7. Impact of the addition of a compound fertilizer on the dissolution of carbonate rock tablets: A column experiment

    International Nuclear Information System (INIS)

    Highlights: → Impact of compound fertilizer on carbonate dissolution is studied by columns. → Compound fertilizer reduced soil pH and increased the leach of ions. → Carbonate dissolution accelerated due to compound fertilizer application. → Impact of fertilizer on the budget of CO2 sink cannot be disregarded. - Abstract: The chemical weathering dynamics of carbonate and the C cycle are strongly influenced by anthropogenic perturbations such as agricultural fertilization. In this study, two columns (a control column and a fertilizer column) with carbonate rock tablets in the bottom of each were established to explore the impact of the addition of a compound fertilizer on the dissolution of carbonate rock tablets. The impacts were assessed from hydro-chemical analyses of the leachates from the two columns and comparison of the amount of dissolution of the carbonate rock tablets. The results showed that NH4+, free CO2, HCO3-,HPO42- and COD increased in the leachate after addition of the compound fertilizer, whereas the pH decreased. The pH decrease was attributed to the release of protons from the nitrification reaction. The amount of dissolution of limestone and dolomite tablets decreased as a result of the compound fertilizer application. Furthermore, the calculated results using Phreeqci software showed that the compound fertilizer reduced the saturation index of calcite and dolomite. Thus, the impact of a compound fertilizer, especially an ammonium fertilizer, on the budget of the CO2 sink cannot be disregarded on either a regional or a global scale.

  8. Immobilization of Bacillus sp. in mesoporous activated carbon for degradation of sulphonated phenolic compound in wastewater

    International Nuclear Information System (INIS)

    Xenobiotic compounds are used in considerable quantities in leather industries besides natural organic and inorganic compounds. These compounds resist biological degradation and thus they remain in the treated wastewater in the unaltered molecular configurations. Immobilization of organisms in carrier matrices protects them from shock load application and from the toxicity of chemicals in bulk liquid phase. Mesoporous activated carbon (MAC) has been considered in the present study as the carrier matrix for the immobilization of Bacillus sp. isolated from Effluent Treatment Plant (ETP) employed for the treatment of wastewater containing sulphonated phenolic (SP) compounds. Temperature, pH, concentration, particle size and mass of MAC were observed to influence the immobilization behavior of Bacillus sp. The percentage immobilization of Bacillus sp. was the maximum at pH 7.0, temperature 20 °C and at particle size 300 μm. Enthalpy, free energy and entropy of immobilization were − 46.9 kJ mol−1, − 1.19 kJ mol−1 and − 161.36 J K−1 mol−1 respectively at pH 7.0, temperature 20 °C and particle size 300 μm. Higher values of ΔH0 indicate the firm bonding of the Bacillus sp. in MAC. Degradation of aqueous sulphonated phenolic compound by Bacillus sp. immobilized in MAC followed pseudo first order rate kinetics with rate constant 1.12 × 10−2 min−1. Highlights: ► Degradation on phenolic syntan using immobilized activated carbon as catalyst. ► Bacillus sp. immobilized cell reactor removed all refractory organic loads. ► The removal mechanism is due to co-metabolism between carbon and organisms. ► The organics are completely metabolized rather than adsorption.

  9. Immobilization of Bacillus sp. in mesoporous activated carbon for degradation of sulphonated phenolic compound in wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Sekaran, G., E-mail: ganesansekaran@gmail.com [Environmental Technology Division, Council of Scientific and Industrial Research (CSIR), Central Leather Research Institute (CLRI), Adyar, Chennai-600 020 (India); Karthikeyan, S. [Environmental Technology Division, Council of Scientific and Industrial Research (CSIR), Central Leather Research Institute (CLRI), Adyar, Chennai-600 020 (India); Gupta, V.K. [Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee-247 667 (India); Department of Chemistry, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Boopathy, R.; Maharaja, P. [Environmental Technology Division, Council of Scientific and Industrial Research (CSIR), Central Leather Research Institute (CLRI), Adyar, Chennai-600 020 (India)

    2013-03-01

    Xenobiotic compounds are used in considerable quantities in leather industries besides natural organic and inorganic compounds. These compounds resist biological degradation and thus they remain in the treated wastewater in the unaltered molecular configurations. Immobilization of organisms in carrier matrices protects them from shock load application and from the toxicity of chemicals in bulk liquid phase. Mesoporous activated carbon (MAC) has been considered in the present study as the carrier matrix for the immobilization of Bacillus sp. isolated from Effluent Treatment Plant (ETP) employed for the treatment of wastewater containing sulphonated phenolic (SP) compounds. Temperature, pH, concentration, particle size and mass of MAC were observed to influence the immobilization behavior of Bacillus sp. The percentage immobilization of Bacillus sp. was the maximum at pH 7.0, temperature 20 Degree-Sign C and at particle size 300 {mu}m. Enthalpy, free energy and entropy of immobilization were - 46.9 kJ mol{sup -1}, - 1.19 kJ mol{sup -1} and - 161.36 J K{sup -1} mol{sup -1} respectively at pH 7.0, temperature 20 Degree-Sign C and particle size 300 {mu}m. Higher values of {Delta}H{sup 0} indicate the firm bonding of the Bacillus sp. in MAC. Degradation of aqueous sulphonated phenolic compound by Bacillus sp. immobilized in MAC followed pseudo first order rate kinetics with rate constant 1.12 Multiplication-Sign 10{sup -2} min{sup -1}. Highlights: Black-Right-Pointing-Pointer Degradation on phenolic syntan using immobilized activated carbon as catalyst. Black-Right-Pointing-Pointer Bacillus sp. immobilized cell reactor removed all refractory organic loads. Black-Right-Pointing-Pointer The removal mechanism is due to co-metabolism between carbon and organisms. Black-Right-Pointing-Pointer The organics are completely metabolized rather than adsorption.

  10. Adsorption of Thiophenic Compounds from Model Diesel Fuel Using Copper and Nickel Impregnated Activated Carbons

    Directory of Open Access Journals (Sweden)

    Ramin Karimzadeh

    2012-10-01

    Full Text Available Adsorption of sulfur compoundsby porous materials is an effective way to produce cleaner diesel fuel.In this study, adsorption of refractory thiophenic sulfur compounds, i.e., benzothiophene (BT, dibenzothiophene (DBT, and 4,6-dimethyldibenzothiophene (4,6-DMDBT in single-solute systems from n-hexane solutions onto metal-impregnated activated carbons was investigated. A hydrogen-treated activated carbon fiber was selectively loaded with Ni, NiO, Cu, Cu2O, and CuO species to systematically assess the impact of each metal species on the adsorption of thiophenic compounds (TC. Metal-loaded adsorbents had the same total metal contents and similar microporosities, but contained different types of copper or nickel species. All metal-loaded adsorbents showed enhanced adsorption of tested TC. Cu2O- or NiO-loaded adsorbents exhibited the highest uptakes, due to more specific interactions between Cu+ or Ni2+ species and TC molecules. The theoretical monolyer coverage of TC on the exposed Cu+ sites was estimated and compared with that calculated from the experimental data. Results suggested catalytic conversion of TC molecules to other compounds on the Cu+ sites, followed by adsorption of reaction products onto the carbon surface or multilayer accumulation of TC molecules on the Cu+sites. TC adsorption uptake of the majority of adsorbents followed the order of: 4,6-DMDBT > DBT > BT due to higher intensity of specific and non-specific interactions of larger TC molecules with adsorbents.

  11. Pulsed amperometric detection at glassy carbon electrodes: A new waveform for sensitive and reproducible determination of electroactive compounds.

    Science.gov (United States)

    Nardiello, Donatella; Palermo, Carmen; Natale, Anna; Quinto, Maurizio; Centonze, Diego

    2015-09-24

    In this work, the application of a new pulsed amperometric detection (PAD) waveform at a glassy carbon electrode, operating in typical chromatographic mobile phases, is proposed for the sensitive and reproducible determination of arylethanolaminic and phenolic moiety based compounds (e.g. beta-agonists and polyphenols). Preliminary experiments by cyclic voltammetry were carried out to investigate the electrochemical behaviour and to select the detection and cleaning electrode potentials. The proposed potential-time profile was designed to prevent the carbon electrode fouling under repeated analyses, thus ensuring a reproducible and sensitive quantitative determination, without the need of any mechanical or chemical electrode cleaning procedure. The waveform electrochemical parameters, including detection and delay times, were optimized in terms of sensitivity, limit of detection and response stability. The optimized waveform allowed the sensitive and stable detection of model compounds, such as clenbuterol and caffeic acid, that showed detection limits of 0.1 μg L(-1) and 14 μg L(-1), quantification limits of 0.4 μg L(-1) and 46 μg L(-1), and linearity up to 100 μg L(-1) (r = 0.9993) and 10 mg L(-1) (r = 0.9998), respectively. Similar results were obtained for other compounds of the same classes, with precision values under repeatability conditions ranging from 3.0 to 5.9%. The proposed method can be then considered as an excellent alternative to the post-column detection of beta-agonists, phenols and polyphenols. PMID:26423623

  12. Carbon-14 ages of Allan Hills meteorites and ice

    Science.gov (United States)

    Fireman, E. L.; Norris, T.

    1982-01-01

    Allan Hills is a blue ice region of approximately 100 sq km area in Antarctica where many meteorites have been found exposed on the ice. The terrestrial ages of the Allan Hills meteorites, which are obtained from their cosmogenic nuclide abundances are important time markers which can reflect the history of ice movement to the site. The principal purpose in studying the terrestrial ages of ALHA meteorites is to locate samples of ancient ice and analyze their trapped gas contents. Attention is given to the C-14 and Ar-39 terrestrial ages of ALHA meteorites, and C-14 ages and trapped gas compositions in ice samples. On the basis of the obtained C-14 terrestrial ages, and Cl-36 and Al-26 results reported by others, it is concluded that most ALHA meteorites fell between 20,000 and 200,000 years ago.

  13. Visualizing lone pairs in compounds containing heavier congeners of the carbon and nitrogen group elements

    Indian Academy of Sciences (India)

    Ram Seshadri

    2001-10-01

    In this mini-review, I discuss some recent work on the stereochemistry and bonding of lone pairs of electrons in divalent compounds of the heavier carbon group elements (SnII, PbII) and in trivalent compounds of the heavier nitrogen group elements (BiIII). Recently developed methods that permit the real-space visualization of bonding patterns on the basis of density functional calculations of electronic structure, reveal details of the nature of selectron lone pairs in compounds of the heavier main group elements - their stereochemistry and their inertness (or lack thereof). An examination of tetragonal 4/ SnO, -PbO and BiOF, and cubic $\\bar{3}$ PbS provides a segue into perovskite phases of technological significance, including ferroelectric PbTiO3 and antiferroelectric/piezoelectric PbZrO3, in both of which the lone pairs on Pb atoms play a pivotal rôle.

  14. Synthesis of carbon-14 labeled Taxol (paclitaxel). [Anticancer agent

    Energy Technology Data Exchange (ETDEWEB)

    Walker, D.G.; Swigor, J.E. (Bristol-Myers Squibb Co., Syracuse, NY (United States). Pharmaceutical Research Inst.); Kant, Joydeep; Schroeder, D.R. (Bristol-Myers Squibb Co., Wallingford, CT (United States). Pharmaceutical Research Inst.)

    1994-10-01

    Reductive cleavage of the C13 side chain of Taxol (1, paclitaxel) followed by regioselective silylation gave 7-triethylsilylbaccatin III (4). 3-O-Triethysilylation of 5 and subsequent reaction with benzoyl chloride-C7-[sup 14]C gave azetidinone 7. Coupling of 4 and 7 followed by deprotection gave 1.26 g of Taxol-N3'-[sup 14]C (11) having a specific activity of 26.5 mCi/mmol and a radiochemical purity of 95%. (author).

  15. Results of excretion analyses on carbon 14 and their interpretation

    International Nuclear Information System (INIS)

    Personal monitoring of routinely radiation exposed persons according to paragraph 25 of the Austrian Radiation Protection Regulation usually can be performed with sufficient accuracy. A real problem, however, exists in the evaluation of the obtained data for calculating the dose commitment. The presented work reports some experiences with a routine monitoring program for 14C and gives a statistical review of the results from urinalysis of employees in the Research Center Seibersdorf for the period 1976-1978. For typical cases of incorporation, the received doses were estimated and proposals for organizing an effective survey program for workers handling 14C were made. (Auth.)

  16. The electrochemical performance of ordered mesoporous carbon/nickel compounds composite material for supercapacitor

    International Nuclear Information System (INIS)

    A series of high performance ordered mesoporous carbon/nickel compounds composites have been synthesized by a combination of incipient wetness impregnation and hydrothermal method for the first time. X-ray diffraction (XRD), N2 adsorption/desorption isotherms and transmission electron microscopy (TEM) are used to characterize the composites derived at the hydrothermal temperature of 125, 150, 175, 200, 250, 275 and 300 oC. The formation of nanosized nickel compounds, fully inside the mesopore system, was confirmed with XRD and TEM. An N2 adsorption/desorption isotherms measurements still revealed mesoporosity for the host/guest compounds. It is noteworthy that an OMC/nickel nitrate hydroxide hydrate composite (OMCN-150) exhibits more excellent performance. Based on the various hydrothermal temperatures of the composite, the capacitance of an OMCN-150 delivering the best electrochemical performance is about 2.4 (5 mV s-1) and 1.5 (50 mV s-1) times of the pristine OMC. The capacitance retention of an OMCN-150 is 96.1%, which indicates that the electrochemical performance of the supercapacitor is improved greatly, and represents novel research and significant advances in the field of electrode composite materials for supercapacitor. -- Graphical abstract: A series of high performance nickel compound/ordered mesoporous carbon composites were synthesized by a combination of incipient wetness impregnation and hydrothermal method for the first time. Display Omitted

  17. Carbon-14 as an indicator of CO2 pollution in cities

    International Nuclear Information System (INIS)

    The combustion of fossil fuels in cities, and especially in industrial areas, releases large quantities of carbon dioxide into the local atmosphere. This carbon dioxide does not contain carbon-14, with the result that the carbon-14 content of the atmospheric carbon dioxide is locally depleted. The degree of depletion provides a measure for the carbon dioxide pollution at the sampling site. Since growing plants represent a convenient average sample of the carbon dioxide in the air, the leaves of deciduous trees can be used for comparing the magnitude of local pollution in different localities during the summer growing period. A series of leaf samples collected in 1973 from Europe, North America and South Africa reveals the expected differences in the degree of pollution. Extreme instances occur in Scholven (Ruhrgebiet, Germany), where the average day-time carbon dioxide content during the summer months is found to be 8.7% above normal, and in Manhatten, New York City, where the corresponding figure is 6.4%. The technique can easily be extended to include the winter months by directly absorbing carbon dioxide in a hydroxide solution during different seasons. The proposed method is sensitive but much less time-consuming than the continuous measurement of the carbon dioxide concentration in the air. It thus lends itself to the monitoring of impact areas of pollution. (author)

  18. Synthesis of carbon-14 labelled CD 271 (6-[3-(1-adamantyl)-4-methoxyphenyl]-2-naphthoic acid): a potential new agent for dermatology

    International Nuclear Information System (INIS)

    6-[3-(1-Adamantyl)-4-methoxyphenyl]-2-naphthoic acid, a promising new compound for the treatment of disorders of keratinization, has been synthesized in [14C]-labelled form from barium[14C]-carbonate via labelled benzene. Benzene-[U-14C] was converted to 4-bromo-methoxybenzene-[phenyl-U-14C] in six steps. Introduction of the adamantyl ring was carried out using 1-acetoxyadamantane under acid catalysis. 2-(1-Adamantyl)-4-bromo-methoxybenzene-[phenyl-U-14C] was converted to a zincate and coupled with methyl 6-bromo-2-naphthoate using a nickel catalyst. The product of the aryl coupling reaction was then saponified to give 6-[3-(1-adamantyl)-4-methoxyphenyl-[phenyl-U-14C

  19. Single, competitive, and dynamic adsorption on activated carbon of compounds used as plasticizers and herbicides.

    Science.gov (United States)

    Abdel daiem, Mahmoud M; Rivera-Utrilla, José; Sánchez-Polo, Manuel; Ocampo-Pérez, Raúl

    2015-12-15

    The main aim of this study was to investigate the single, competitive, and dynamic adsorption of phthalic acid (PA), bisphenol A (BPA), diphenolic acid (DPA), 2,4-dichlorophenoxy-acetic acid (2,4-D), and 4-chloro-2-methylphenoxyacetic acid (MCPA) on two activated carbons with different chemical natures and similar textural characteristics. The adsorption mechanism was also elucidated by analyzing the influence of solution pH and ionic strength. The activated carbons demonstrated high adsorption capacity to remove all micropollutants due to the presence of active sites on their surfaces, which increase dispersive interactions between the activated carbon graphene layers and the aromatic ring of pollutants. The adsorption capacity of the activated carbons increased in the order: DPAcarbon decreased by around 50% and 70% in the presence of DPA and BPA, respectively, indicating that both compounds are adsorbed on the same adsorption sites of the activated carbon. PMID:26282767

  20. Study of rock porosity by impregnation with carbon-14- methylmethacrylate

    International Nuclear Information System (INIS)

    An investigation of porosity and spatial porosity distribution to enable the determination of mineral specific characteristics was conducted on tonalite and mica gneiss from the Olkiluoto site in Eurajoki. The method that was used involved impregnation of the rocks with 14C-methyl-methacrylate, irradiation polymerization, autoradiography and optical densitometry with application of digital image processing techniques. The accuracy of the method was estimated by comparing the results with those obtained by water impregnation method. The 14C-polymethyl- methacrylate (14CPMMA) method provided an effective means of determining the different porous phases in the rock matrix which vary in their diffusive properties. With increased tracer activity and an improved measurement system, the 14CPMMA method allowed porosity detection down to 0.05 vol.per cent with spatial resolution of 20 μm. The porosity was found to lie at grain boundaries of the fresh unaltered rock. The spatial porosity was fairly evenly distributed in the rock with a fine grain size. Anisotropy of porous phases was observed in fine- and medium-grained tonalite and mica gneiss samples. Inter- and intracrystalline fissures of quartz and plagioclase were observed. Most porous phases, with 0.6-1.6 vol. per cent porosity, were biotite, serisite, epidote and cordierite minerals. The bulk porosities of the samples varied between 0.10 vol.per cent and 0.19 vol.per cent. (orig.) (9 refs., 16 figs., 1 tab.)

  1. Assessment of carbon-14 control technology and costs for the LWR fuel cycle. Final report

    International Nuclear Information System (INIS)

    The report is an effort to incorporate present knowledge of carbon-14 behavior in Light Water Reactors and Fuel Reprocessing Plants into Designs compatible with present technology. The impact of radioactive effluents are considered according to the traditional measure of maximum radiation dose to individuals, summation of individual annual doses to obtain a total population dose, and the environmental dose commitment. The sources of carbon-14 in LWR's and fuel reprocessing facilities are identified. Systems for the removal of carbon-14 in existing and future plants are addressed from both a technological and economic standpoint. Existing technology indicates that caustic scrubbing is the most cost-effective alternative for concurrently removing C-14 from waste-gas streams and leaving it in a form compatible with permanent disposal conditions

  2. Immobilization of carbon 14 contained in spent fuel hulls through melting-solidification treatment

    International Nuclear Information System (INIS)

    The melting-solidification treatment of spent nuclear fuel hulls is a potential technique to improve immobilization/stabilization of carbon-14 which is mobile in the environment due to its weakly absorbing properties. Carbon-14 can be immobilized in a solid during the treatment under an inert gas atmosphere, where carbon is not oxidized to gaseous form and remains in the solid. A series of laboratory scale experiments on retention of carbon into an alloy waste form was conducted. Metallic zirconium was melted with metallic copper (Zr/Cu=8/2 in weight) at 1200 deg C under an argon atmosphere. Almost all of the carbon remained in the resulting zirconium-copper alloy. (authors)

  3. Steam reforming of cyclic model compounds of bio-oil over Ni-based catalysts: Product distribution and carbon formation

    DEFF Research Database (Denmark)

    Trane-Restrup, Rasmus; Jensen, Anker Degn

    2015-01-01

    significantly by adding oxygen to the feed at a cost of a lower yield of H2. Stable operation was observed initially (first 4h) in the OSR of all compounds, but experiments over 24h showed signs of deactivation due to an accelerated rate of carbon deposition in the SR of furfural and guaiacol. Furthermore...... yields in the SR of guaiacol and temperatures of 780°C were needed to totally convert guaiacol to carbon oxides and H2.Carbon deposition was observed in the SR of all three model compounds and was most severe for guaiacol followed by furfural and 2-methylfuran. The carbon deposition could be reduced...

  4. Displacement of carbon-14 labelled amino acids from leaves

    International Nuclear Information System (INIS)

    The displacement of amino acids from nature leaves was investigated. The amino acids (Ala, Asn, Asp, Glu, Gln, Val, Leu, Lys, Ser, Pro) were applied on the leaves in L-form, uniformly labelled with 14C, and the type and direction of displacement have been observed. Most of the studies have been carried out on bush beans aged 3 to 4 weeks. The experiments were carried out in climatic chambers; in one case, barley plants just reaching maturity were used. In order to find out whether the applied amino acids were also displaced in their original form, freeze-dried plants were extracted and the 14C activity of the various fraction was determined. The radioactivity of some free amino acids was determined after two-dimensional separation by thin film chromatography. (orig./HK)

  5. Groundwater's carbon 14 age distribution in the Konya closed basin

    International Nuclear Information System (INIS)

    The Konya Closed basin extending from Taurids at the south toward Salt Lake at the north covers and area of 80,000 sq.km. Apart from the surface water transfer from neighboring basins, groundwater is the only potable water resource in this area where determination of groundwater age is crucial in view of understanding of the timing or recharge and flow dynamics. 14C model ages at 8 drilling wells scattered along the regional flow path extending between Taurids and Salt Lake were determined. Results indicate that groundwater age increases progressively from recent to ca. 40 ky BP along the flow path. This linear increase with distance from recharge area suggests a homogenous groundwater velocity distribution (3m/year) in the basin. 14C model and hydraulic (kinematic) ages are in agreement. 18O content of groundwater points out a steady decrease of recharge temperature (up to 60C) throughout the Wurm glacial period

  6. Determination of carbon-14 in environmental level, solid reference materials

    Energy Technology Data Exchange (ETDEWEB)

    Blowers, Paul, E-mail: paul.blowers@cefas.co.uk [Cefas Lowestoft Laboratory, Pakefield Road, Lowestoft, Suffolk, NR33 0HT (United Kingdom); Caborn, Jane, E-mail: jane.a.caborn@nnl.co.uk [NNL, Springfields, Salwick, Preston, Lancashire, PR4 0XJ (United Kingdom); Dell, Tony [Veterinary Laboratories Agency, New Haw, Addlestone, Surrey, KT15 3NB (United Kingdom); Gingell, Terry [DSTL, Radiation Protection Services, Crescent Road, Alverstoke, Gosport, Hants, PO12 2DL (United Kingdom); Harms, Arvic [National Physical Laboratory, Hampton Road, Teddington, Middlesex, TW11 0LW (United Kingdom); Long, Stephanie [Radiological Protection Institute of Ireland, 3 Clonskeagh Square, Clonskeagh Road, Dublin 14, Ireland (United Kingdom); Sleep, Darren [Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster, LA1 4AP (United Kingdom); Stewart, Charlie [UKAEA (Waste Management Group), Chemical Support Services, D1310/14, Dounreay, Thurso, Caithness, KW14 7TZ (United Kingdom); Walker, Jill [Radiocarbon Dating, The Old Stables, East Lockinge, Wantage, Oxon OX12 8QY (United Kingdom); Warwick, Phil E. [GAU-Radioanalytical, National Oceanography Centre Southampton, European Way, Southampton, SO14 3ZH (United Kingdom)

    2011-10-15

    An intercomparison exercise to determine the {sup 14}C activity concentrations in a range of solid, environmental level materials was conducted between laboratories in the UK. IAEA reference materials, C2, C6 and C7, and an in-house laboratory QA material were dispatched in 2006 to ten laboratories comprising of members of the Analyst Informal Working Group (AIWG) and one other invited party. The laboratories performed the determinations using a number of techniques, and using the results each one was evaluated in terms of levels of precision, sensitivity and limits of detection. The results of the study show that all techniques are capable of successfully analysing {sup 14}C in environmental level materials, however, a shortage of certified environmental reference materials exists. The suitability of the IAEA reference materials and other material for use as reference materials was also assessed.

  7. Determination of carbon-14 in environmental level, solid reference materials

    International Nuclear Information System (INIS)

    An intercomparison exercise to determine the 14C activity concentrations in a range of solid, environmental level materials was conducted between laboratories in the UK. IAEA reference materials, C2, C6 and C7, and an in-house laboratory QA material were dispatched in 2006 to ten laboratories comprising of members of the Analyst Informal Working Group (AIWG) and one other invited party. The laboratories performed the determinations using a number of techniques, and using the results each one was evaluated in terms of levels of precision, sensitivity and limits of detection. The results of the study show that all techniques are capable of successfully analysing 14C in environmental level materials, however, a shortage of certified environmental reference materials exists. The suitability of the IAEA reference materials and other material for use as reference materials was also assessed.

  8. Study of a Dolomitic Aquifer with Carbon-14 and Tritium

    International Nuclear Information System (INIS)

    The Dolomite Series which outcrops over an extensive area of the Transvaal is frequently subdivided into separate groundwater compartments by vertical diabase dykes to form well-defined aquifers which usually overflow in strong springs at the lowest point on the surface. The hydrology of one such compartment has been analysed to provide figures for the aquifer characteristics which can be compared with the results of the isotope data. The recharge rate of the aquifer is found to be 17.7 mm/yr and the storage capacity is about 57 times the annual recharge. Expressions for the age distribution in an idealized model of the aquifer and the age of the water discharging from the spring are derived and used to determine the recharge and capacity from the 14C and tritium data. The initial 14C content of the groundwater varies from 80 to 90% with the result that this isotope is relatively unsuitable for quantitative deductions of recharge etc. Both 14C and tritium show a linear increase in age with depth in accordance with the theory. From the tritium results a recharge rate of 11.5 mm/yr, and a storage capacity of 106 times the annual recharge is deduced. Practically the same results are obtained from the tritium content of the spring water if the initial tritium content of the recharge, extrapolated from the age-depth curve (7 TU), is used and the relationship between average age and apparent age of the discharge employed. (author)

  9. Study of a dolomitic aquifer with carbon-14 and tritium

    International Nuclear Information System (INIS)

    The Dolomite Series which outcrops over an extensive area of the Transvaal is frequently subdivided into separate groundwater compartments by vertical diabase dykes to form well-defined aquifers which usually overflow in strong springs at the lowest point on the surface. The hydrology of one such compartment has been analysed to provide figures for the aquifer characteristics which can be compared with the results of the isotope data. The recharge rate of the aquifer is found to be 17.7 mm/yr and the storage capacity is about 57 times the annual recharge. Expressions for the age distribution in an idealized model of the aquifer and the age of the water discharging from the spring are derived and used to determine the recharge and capacity from the 14C and tritium data. The initial 14C content of the groundwater varies from 80 to 90% with the result that this isotope is relatively unsuitable for quantitative deductions of recharge etc. Both 14C and tritium show a linear increase in age with depth in accordance with the theory. From the tritium results a recharge rate of 11.5 mm/yr, and a storage capacity of 106 times the annual recharge is deduced. Practically the same results are obtained from the tritium content of the spring water if the initial tritium content of the recharge, extrapolated from the age-depth curve (7 TU), is used and the relationship between average age and apparent age of the discharge employed. (author)

  10. Characteristics of 14C and 13C of carbonate aerosols in dust storm events in China

    Science.gov (United States)

    Chen, Bing; Jie, Dongmei; Shi, Meinan; Gao, Pan; Shen, Zhenxing; Uchida, Masao; Zhou, Liping; Liu, Kexin; Hu, Ke; Kitagawa, Hiroyuki

    2015-10-01

    In contrast with its decrease in western China deserts, the dust storm event in eastern China, Korea, and Japan shows an increase in frequency. Although the drylands in northeastern China have been recognized as an important dust source, the relative contributions of dust transport from the drylands and deserts are inconclusive, thus the quantification of dust storm sources in downwind area remains a challenge. We measured the 14C and 13C contents in carbonates of dust samples from six sites in China, which were collected for the duration of dust storm events in drylands, deserts, and urban areas. The δ13C of the dryland dust samples considerably varied in a range of - 9.7 to - 5.0‰, which partly overlapped the desert dust carbonate δ13C ranges. The 14C content of the dryland dust carbonates showed a narrow range of 60.9 ± 4.0 (as an average and 1 SD of five samples) percent modern carbon (pMC), indicating the enrichment of modern carbonate. Dust samples in desert regions contained relatively aged carbonates with the depleting 14C showing of 28.8 ± 3.3 pMC. After the long-range transport of the western China desert dust plume, the carbonates collected at the southern China remained the depletion of 14C (33.5 ± 5.3 pMC) as in the desert regions. On the other hand, the samples of dust storm events at the urban areas of eastern China showed an enrichment of 14C contents (46.2 ± 5.0 pMC, n = 7), which might be explained by the stronger contribution of modern-carbonate-rich dryland dust.

  11. Two dimensional model study of atmospheric transport using carbon-14 and strontium-90 as inert tracers

    International Nuclear Information System (INIS)

    This study tests the transport processes in the LLNL two-dimensional chemical-radiative-transport model using recently reanalyzed carbon-14 and strontium-90 data. These radioactive tracers were produced bythe atmospheric nuclear bomb tests of 1952--58 and 1961--62, and they were measured at a few latitudes up to 35 kilometers over the period 1955--1970. Selected horizontal and vertical eddy diffusion coefficients were varied in the model to test their sensitivity to short and long term transpose of carbon-14. A sharp transition of Kzz and Kyy through the tropopause, as opposed to a slow transition between the same limiting values, shows a distinct improvement in the calculated carbon-14 distributions, a distinct improvement in the calculated seasonal and latitudinal distribution of ozone columns (relative to TOMS observations), and a very large difference in the calculated ozone reduction by a possible fleet of High Speed Civil Transports. Calculated northern hemisphere carbon-14 is more sensitive to variation of Kyy than are global ozone columns. Strontium-90 was used to test the LLNL tropopause height at four different latitudes. Starting with the 1960 background distribution of carbon-14, we calculate the input of carbon-14 as the sum of each nuclear test of the 1961--62 series, using two bomb-cloud rise models. With the Seitz bomb-rise formulation in the LLNL model, we find good agreement between calculated and observedcarbon-14 (with noticeable exceptions at the north polar tropopause and the short-term mid-latitude mid-stratosphere) between 1963 and 1970

  12. Emissions of carbon species, organic polar compounds, potassium, and mercury from prescribed burning activities

    Science.gov (United States)

    Zhang, Y.; Obrist, D.; Zielinska, B.; Gerler, A.

    2012-04-01

    Biomass burning is an important emission source of pollutants to the atmosphere, but few studies have focused on the chemical composition of emissions from prescribed burning activities. Here we present results from a sampling campaign to quantify particulate-phase emissions from various types of prescribed fires including carbon species (Elemental Carbon: EC; Organic Carbon: OC; and Total Carbon: TC); polar organic compounds (12 different compounds and four functional classes); water-soluble potassium (K+); and mercury (Hg). We measured emissions from the following types of prescribed biomass burning in the Lake Tahoe basin located on the California/Nevada border: (i) log piles stacked and dried in the field; (ii) log piles along with green understory vegetation; and (iii) understory green vegetation and surface litter; further emissions were collected from burns conducted in a wood stove: (iv) dried wooden logs; (v) green foliage of understory vegetation collected from the field; and (vi) surface organic litter collected from the field; finally, samples were also taken from (vii) ambient air in residential areas during peak domestic wood combustion season. Results show that OC/EC ratios of prescribed burns in the field ranged from 4 to 10, but lower values (around 1) were observed in controlled stove fires. These results are consistent with an excess of OC emissions over EC found in wildfires. OC/EC ratios, however, showed clear separations between controlled wood stove combustion (higher EC) and prescribed burns in the field (lower EC). We attribute this difference to a higher combustion temperatures and dominance of flaming combustion in wood stove fires. OC positively and linearly correlated to the sum of polar organic compounds across all burn types (r2 of 0.82). The most prevalent group of polar compounds emitted during prescribed fires was resin acids (dehydroabietic, pimaric, and abietic acids), followed by levoglucosan plus mannositol. Negligible

  13. A synthetic approach to carbon-14 labeled anti-bacterial naphthyridine and quinolone carboxylic acids

    Energy Technology Data Exchange (ETDEWEB)

    Ekhato, I.V.; Huang, C.C. (Parke, Davis and Co., Ann Arbor, MI (United States))

    1993-09-01

    Labeled versions of (S)-clinafloxacin (1) and two napththyridine carboxylic acid anti-bacterial compounds 2 and 3 which are currently in development were synthesized. Preparations started from hitherto unknown bromo compounds 22 and 10, from which the corresponding [sup 14]C-labeled aromatic carboxylic acids 23 and 12 were generated by metal-halogen exchange followed by carboxylation reaction. Details of these preparations are given. (author).

  14. The Effects of Silica/Carbon Black Ratio on the Dynamic Properties of the Tread compounds in Truck Tires

    OpenAIRE

    Zafarmehrabian, Ramin; Gangali, Saeed Taghvaei; Ghoreishy, Mir Hamid Reza; Davallu, Mehran

    2012-01-01

    NR is the major constituent in the rubber compound used for the tread on the truck tires. A general compound formulation of the tire tread includes NR and BR as polymer base and carbon black as the reinforcing filler, and curative components. In this paper the effects of dual filler system (carbon black and precipitated silica) on the dynamic properties of tire treat has been studied. The results show by increasing of precipitated silica, significant improvement was observed in fatigue resist...

  15. Characteristics study of a system for carbon 14 dating

    International Nuclear Information System (INIS)

    The developing of a radiocarbon dating laboratory, specially built to deal with carbonate samples from underground water, at the Institute de Energia Atomica, required the optimization of a benzene synthetizer, and also of the operative conditions of the liquid scintillator counter, used in sample measurements. An average yield of about 70% was obtained in our benzenic synthesis. If more refined conditions were used, better results could have been obtained, but the reported yield is good enough for our necessities. A comparison of the ages of several shell samples was done between the Geochronology Laboratory, belonging to the Instituto de Geociencias, at Sao Paulo University and our dating laboratory. The agreement between the results was fairly good, according to the precision required

  16. Source and age of carbon in peatland surface waters: new insights from 14C analysis

    Science.gov (United States)

    Billett, Michael; Garnett, Mark; Dinsmore, Kerry; Leith, Fraser

    2013-04-01

    Peatlands are a significant source of carbon to the aquatic environment which is increasingly being recognised as an important flux pathway (both lateral and vertical) in total landscape carbon budgets. Determining the source and age of the carbon (in its various forms) is a key step to understanding the stability of peatland systems as well as the connectivity between the soil carbon pool and the freshwater environment. Novel analytical and sampling methods using molecular sieves have been developed for (1) within-stream, in situ sampling of CO2 in the field and (2) for the removal/separation of CO2 in the laboratory prior to 14C analysis of CH4. Here we present dual isotope (δ13C and 14C) data from freshwater systems in UK and Finnish peatlands to show that significant differences exist in the source and age of CO2, DOC (dissolved organic carbon) and POC (particulate organic carbon). Individual peatlands clearly differ in terms of their isotopic freshwater signature, suggesting that carbon cycling may be "tighter" in some systems compared to others. We have also measured the isotopic signature of different C species in peatland pipes, which appear to be able to tap carbon from different peat depths. This suggests that carbon cycling and transport within "piped-peatlands" may be more complex than previously thought. Some of our most recent work has focussed on the development of a method to measure the 14C component of CH4 in freshwaters. Initial results suggest that CH4 in peatland streams is significantly older than CO2 and derived from a much deeper source. We have also shown that the age (but not the source) of dissolved CO2 changes over the hydrological year in response to seasonal changes in discharge and temperature. Radiocarbon measurements in the peat-riparian-stream system suggest that a significant degree of connectivity exists in terms of C transport and cycling, although the degree of connectivity differs for individual C species. In summary, 14C

  17. Carbon-14 as a Tracer of Land-to-Ocean Organic Carbon Transfers in Eight Northeastern US Rivers

    Science.gov (United States)

    Hossler, K.; Bauer, J. E.

    2011-12-01

    Rivers link the terrestrial and ocean carbon cycles, transporting and transforming an aggregate of upstream C exports. We used natural abundance 14C and 13C to identify controls on particulate and dissolved organic carbon (POC and DOC, respectively) for rivers draining eight different watershed subregions in the northeastern US. The rivers presented a range of lithology, land-use and other anthropogenic impacts (e.g., presence of nuclear and fossil-fuel power plants and waste-water treatment plants). POC and DOC δ13C signatures (per sample) ranged from -34 % to -22 % and -28 % to -15 %, respectively; while discharge-weighted means ranged from -29 % to -26 % (POC) and -28 % to -25 % (DOC), reflecting the predominance of C3 vegetation in the region. In contrast, Δ14C signatures were much more variable, ranging from -224 % to +1,230 % for POC and -233 % to +1,960 % for DOC (per sample), and with discharge-weighted means ranging from -160 % to +340 % (POC) and -60 % to +480 % (DOC). Samples depleted in 14C (i.e., Δ14C systems was of organic materials highly enriched in 14C (Δ14C = +163 % to +1,960 %), most likely because of 14C inputs from upstream nuclear power plants. Nuclear reactors were also present in two of the other watersheds, but did not elevate the 14C signatures. For all four watersheds with nuclear reactors, however, radiocarbon inputs likely resulted in underestimation of aged C contributions. Studies utilizing 14C as a tracer for natural and anthropogenic controls on C and organic matter inputs and fluxes, should take into consideration the various and sometimes opposing influences on the integrated signatures.

  18. Rapid localization of carbon 14-labeled molecules in biological samples by ion mass microscopy

    International Nuclear Information System (INIS)

    We report here on the ability of secondary ion mass spectrometry (SIMS) to provide rapid imaging of the intracellular distribution of 14C-labeled molecules. The validity of this method, using mass discrimination of carbon 14 atoms, was assessed by imaging the distribution of two molecules of well-known metabolism, [14C]-thymidine and [14C]-uridine, incorporated by human fibroblasts in culture. As expected, 14C ion images showed the presence of [14C]-thymidine in the nucleus of dividing cells, whereas [14C]-uridine was present in the cytoplasm as well as the nucleus of all cells, with a large concentration in the nucleoli. The time required to obtain the distribution images with the SMI 300 microscope was less than 6 min, whereas microautoradiography, the classical method for mapping the tissue distribution of 14C-labeled molecules, usually requires exposure times of several months. Secondary ion mass spectrometry using in situ mass discrimination is proposed here as a very sensitive method which permits rapid imaging of the subcellular distribution of molecules labeled with carbon 14

  19. Carbon-14 transfer into rice plants from a continuous atmospheric source: observations and model predictions

    International Nuclear Information System (INIS)

    Carbon-14 (14C) is one of the most important radionuclides from the perspective of dose estimation due to the nuclear fuel cycle. Ten years of monitoring data on 14C in airborne emissions, in atmospheric CO2 and in rice grain collected around the Tokai reprocessing plant (TRP) showed an insignificant radiological effect of the TRP-derived 14C on the public, but suggested a minor contribution of the TRP-derived 14C to atmospheric 14C concentrations, and an influence on 14C concentrations in rice grain at harvest. This paper also summarizes a modelling exercise (the so-called rice scenario of the IAEA's EMRAS program) in which 14C concentrations in air and rice predicted with various models using information on 14C discharge rates, meteorological conditions and so on were compared with observed concentrations. The modelling results showed that simple Gaussian plume models with different assumptions predict monthly averaged 14C concentrations in air well, even for near-field receptors, and also that specific activity and dynamic models were equally good for the prediction of inter-annual changes in 14C concentrations in rice grain. The scenario, however, offered little opportunity for comparing the predictive capabilities of these two types of models because the scenario involved a near-chronic release to the atmosphere. A scenario based on an episodic release and short-term, time-dependent observations is needed to establish the overall confidence in the predictions of environmental 14C models

  20. Study of a method of detection for natural carbon-14 using a liquid scintillator, recent variations in the natural radio-activity due to artificial carbon-14 (1963); Etude d'une methode de detection du carrons 14 naturel, utilisant un scintillateur liquide - variations recentes de l'activite naturelle dues au carbone 14 artificiel (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Leger, C. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1963-06-15

    Among the various natural isotopes of carbon, a radioactive isotope, carbon-14, is formed by the action of secondary neutrons from cosmic rays on nitrogen in the air. Until 1950, the concentration of this isotope in ordinary carbon underwent weak fluctuations of about 2-3 per cent. The exact measurement of this concentration 6 X 10{sup 12} Ci/gm of carbon, and of its fluctuations, are difficult and in the first part of this report a highly sensitive method is given using a liquid scintillator. Since 1950 this natural activity has shown large fluctuations because of the carbon-14 formed during nuclear explosions, and in the second part, the evolution in France of this specific activity of carbon in the atmosphere and biosphere is examined. In the last part is studied the local increase in carbon activity in the atmosphere around the Saclay site, an increase caused by the carbon-14 given off as C{sup 14}O{sub 2}, by the reactors cooled partially with exterior air. (author) [French] Parmi les differents isotopes naturels du carbone, un isotope radioactif, le carbone 14, est forme par l'action de neutrons secondaires due aux rayons cosmiques sir l'azote de l'air. Jusqu'en 1950, la concentration de cet isotope dans le carbone ordinaire est soumise a des fluctuations de faible amplitude, de l'ordre de 2 a 3 pour cent. Les mesures precises de cette concentration, 6. 10{sup -12} Ci/g de carbone, et de ses fluctuations sont delicates, et dans la premiere partie de ce rapport, on decrit une methode de detection a grande sensibilite utilisant un scintillateur liquide. Depuis 1950, cette activite naturelle subit des fluctuations importantes dues au carbone 14 forme lors des explosions nucleaires, et dans la seconde partie, on examine l'evolution en France de l'activite specifique du carbone de l'atmosphere et ce la biosphere. Dans la derniere partie, on etudie l'accroissement local de l'activite du carbone de l'air aux

  1. Phase relation of LaFe11.6Si1.4 compounds annealed at different high-temperature and the magnetic property of LaFe11.6−CoSi1.4 compounds

    Indian Academy of Sciences (India)

    Xiang Chen; Yungui Chen; Yongbai Tang

    2012-04-01

    LaFe11.6Si1.4 compounds are annealed at different high temperatures from 1323 to 1623 K. The powder X-ray diffraction patterns show that large amount of NaZn13-type phase begins to be observed in LaFe11.6Si1.4 compound after being annealed at 1423 K for 5 h. In the temperature range from 1423 to 1523 K, the -Fe and LaFeSi phases rapidly decrease to form 1:13 phase. LaFeSi phase is rarely observed in the XRD pattern in the LaFe11.6Si1.4 compound annealed at 1523 K (5 h).With annealing temperature increasing to 1573 K and 1673 K, La5Si3 phase is detected, and there is a certain amount of LaFeSi phase when the annealing temperature is 1673 K. The amount of impurity phases in the LaFe11.6Si1.4 compound annealed by the two-stage annealing consisting of high temperature (>1523 K) and 1523 K is larger than that of the single stage annealing at 1523 K under the same time. According to the results of different high-temperature annealing, LaFe11.6−CoSi1.4 (0.1 ≤ ≤ 0.8) compounds are annealed at 1523 K (5 h). The main phase is NaZn13-type phase, and the impurity phase is a small amount of -Fe in LaFe11.6−CoSi1.4 compounds. With increase in Co content from = 0.1 to 0.8, the Curie temperature C, goes up from 207 to 285 K. The introduction of Co element weakens the itinerant electron metamagnetic transition, and also results in the change of magnetic transition type from first to second order at about = 0.5. The magnetic entropy change decreases from 19.94 to 4.57 J /kg K with increasing Co concentration at a low magnetic field of 0–2 T. But the magnetic hysteresis loss around C reduces remarkably from 26.2 J /kg for = 0.1 to 0 J /kg for = 0.8.

  2. Linear solvation energy relationships (LSER) for adsorption of organic compounds by carbon nanotubes.

    Science.gov (United States)

    Ersan, Gamze; Apul, Onur G; Karanfil, Tanju

    2016-07-01

    The objective of this paper was to create a comprehensive database for the adsorption of organic compounds by carbon nanotubes (CNTs) and to use the Linear Solvation Energy Relationship (LSER) technique for developing predictive adsorption models of organic compounds (OCs) by multi-walled carbon nanotubes (MWCNTs) and single-walled carbon nanotubes (SWCNTs). Adsorption data for 123 OCs by MWCNTs and 48 OCs by SWCNTs were compiled from the literature, including some experimental results obtained in our laboratory. The roles of selected OCs properties and CNT types were examined with LSER models. The results showed that the r(2) values of the LSER models displayed small variability for aromatic compounds smaller than 220 g/mol, after which a decreasing trend was observed. The data available for aliphatics was mainly for molecular weights smaller than 250 g/mol, which showed a similar trend to that of aromatics. The r(2) values for the LSER model on the adsorption of aromatic and aliphatic OCs by SWCNTs and MWCNTs were relatively similar indicating the linearity of LSER models did not depend on the CNT types. Among all LSER model descriptors, V term (molecular volume) for aromatic OCs and B term (basicity) for aliphatic OCs were the most predominant descriptors on both type of CNTs. The presence of R term (excess molar refractivity) in LSER model equations resulted in decreases for both V and P (polarizability) parameters without affecting the r(2) values. Overall, the results demonstrate that successful predictive models can be developed for the adsorption of OCs by MWCNTs and SWCNTs with LSER techniques. PMID:27064209

  3. Vertical transport of carbon-14 into deep-sea food webs

    Science.gov (United States)

    Pearcy, W. G.; Stuiver, Minze

    1983-04-01

    During the years 1973 to 1976 the carbon-14 content was higher in epipelagic and vertically migrating, upper mesopelagic animals (caught between 0 and 500 m) than in lower mesopelagic, bathypelagic, and abyssobenthic animals (500 to 5180 m) in the northeastern Pacific Ocean. Only one species of deep-sea fish had a Δ14C value as high as surface-caught fish. The 14C content of most animals was higher pre-bomb levels, but the relatively low 14C content of most deep-sea animals indicates that the majority of their carbon was not derived directly from a near-surface food chain labeled with bomb carbon. A mean residence time of about 35 y was estimated for the organic carbon pool for abyssobenthic animals based on the relative increase of radiocarbon in surface-dwelling animals since 1967. The results suggest that rapidly sinking particles from surface waters, such as fecal pellets, are not the major source of organic carbon for deep-sea fishes and large benthic invertebrates.

  4. Exposure to carbon monoxide, respirable suspended particulates, and volatile organic compounds while commuting by bicycle

    International Nuclear Information System (INIS)

    A portable air sampling system has been used to assess exposures to various substances while commuting by bicycle in an urban area. The major source of pollutants in this situation is motor vehicle exhaust emissions. Carbon monoxide, measured by electrochemical detection, was found at peak concentrations in excess of 62 ppm, with mean values over 16 individual 35-mm journeys being 10.5 ppm. Respirable suspended particulates, averaged over each journey period, were found at higher concentrations (mean 130 μg m-3) than would be expected in indoor situations. Mean exposure to benzene (at 56 μg m-3) and other aromatic volatile organic compounds was also relatively high. The influence of wind conditions on exposure was found to be significant. Commuting exposures to carbon monoxide, respirable suspended particulates, and aromatic VOCs were found to be higher than exposures in a busy high street and on common parkland

  5. General synthesis of carbon nanocages and their adsorption of toxic compounds from cigarette smoke

    Science.gov (United States)

    Li, Guangda; Yu, Hongxiao; Xu, Liqiang; Ma, Qiang; Chen, Chao; Hao, Qin; Qian, Yitai

    2011-08-01

    Carbon nanocages (CNCs) have been synthesized through a simple approach using different alcohols and ferrous oxalate as reactants at 550 °C for 12 h in a sealed autoclave. The lengths of the sides of the CNCs are about 200-350 nm and the wall thicknesses are about 10-15 nm. The formation mechanism of the CNCs is also discussed, based on the experimental results. These CNCs show excellent removal efficiency for phenolic compounds, ammonia, and total particulate matter from cigarette smoke. The adsorption capability of CNCs prepared from ethanol is much higher than that of other samples. For example, the efficiency of 5 mg CNCs (ethanol) for removing the six phenolic compounds p-dihydroxybenzene, m-dihydroxybenzene, o-dihydroxybenzene, phenol, m-cresol, and o-cresol can reach 57.31%, 62.25%, 65.58%, 75.95%, 54.34% and 59.43%, respectively, while that of the commercial activated carbon (5 mg) can only reach 29.02%, 33.93%, 35.00%, 36.00%, 20.33% and 36.19%, respectively, under the same conditions.Carbon nanocages (CNCs) have been synthesized through a simple approach using different alcohols and ferrous oxalate as reactants at 550 °C for 12 h in a sealed autoclave. The lengths of the sides of the CNCs are about 200-350 nm and the wall thicknesses are about 10-15 nm. The formation mechanism of the CNCs is also discussed, based on the experimental results. These CNCs show excellent removal efficiency for phenolic compounds, ammonia, and total particulate matter from cigarette smoke. The adsorption capability of CNCs prepared from ethanol is much higher than that of other samples. For example, the efficiency of 5 mg CNCs (ethanol) for removing the six phenolic compounds p-dihydroxybenzene, m-dihydroxybenzene, o-dihydroxybenzene, phenol, m-cresol, and o-cresol can reach 57.31%, 62.25%, 65.58%, 75.95%, 54.34% and 59.43%, respectively, while that of the commercial activated carbon (5 mg) can only reach 29.02%, 33.93%, 35.00%, 36.00%, 20.33% and 36.19%, respectively, under

  6. The fate of organic compounds in a cement-based repository: impact on the engineered barrier and the release of C-14 from the near field

    International Nuclear Information System (INIS)

    The degradation of organic materials is taken into account in the safety analysis for a L/ILW (Low- and intermediate-level radioactive waste) repository in Switzerland with the aim of assessing possible impacts on the cement barrier. The waste forms to be disposed of in the planned L/ILW repository will contain HMW polymers and LMW monomeric organic materials. It is anticipated that these organic materials have different degradation rates and therefore different life times in a repository. While the decomposition of LMW organics is expected to be fast and complete during the oxic and early anoxic states of a repository, i.e. before and shortly after repository closure, the decomposition of the HMW polymeric materials is expected to be very slow and, for some materials, to occur over the entire life time of the repository. The degradation of organic materials generates CO2 which gives rise to carbonation of the cement barrier. The maximum acceptable loading of organics in the near field with no detrimental effect on radionuclide immobilization can be estimated on the assumption that at maximum 2/3 of the total portlandite inventory of hydrated cement is allowed to convert to CaCO3 in the case of waste compartments for which the cementitious barrier should remain intact. The maximum loading is determined by the inventory of the organic material under consideration as well as the carbon content and the oxidation state of carbon of the material. Carbon-14 bound in organic compounds is considered to be an important contributor to the annual dose released from a L/ILW repository. While the 14C inventory is well known, the chemical speciation of 14C in the cementitious near field upon liberation in the course of the corrosion of activated steel is only poorly understood. Preliminary corrosion tests with non-activated steel powders show the formation of gaseous and dissolved organic carbon species, e.g. alkanes/alkenes, alcohols, aldehydes, and carboxylic acids, containing

  7. Sampling and monitoring of carbon-14 in gaseous effluents from nuclear facilities

    International Nuclear Information System (INIS)

    This study reviews the possibilities from sampling and monitoring C-14 in gaseous effluents from nuclear facilities. After oxidation of various forms of carbon-14 in the off-gas into CO2 three main processes for trapping are used either separately or in combination. These are sorption, freezing and chemical processes. Absorption in alkaline solutions or solids or molecular sieve adsorption are the most frequently used methods. The main counting methods used are gas proportional counting and liquid scintillation counting

  8. Carbon-14 production compared to oxygen isotope records from Camp Century, Greenland and Devon Island, Canada

    International Nuclear Information System (INIS)

    Carbon-14 production rate variations that are not explainable by geomagnetic changes are thought to be in antiphase with solar activity and as such should be in antiphase with paleotemperature records or proxy temperature histories such as those obtainable from oxygen isotope analyses of ice cores. Oxygen isotope records from Camp Century, Greeland and Devon Island Ice Cap are in phase with each other over thousands of years and in antiphase to the 14C production rate residuals. (Auth.)

  9. Design, Synthesis and Biological Evaluation of 1,4-Disubstituted-3,4-dihydroisoquinoline Compounds as New Tubulin Polymerization Inhibitors

    Directory of Open Access Journals (Sweden)

    Ling Zhang

    2015-05-01

    Full Text Available A series of 1,4-disubstituted-3,4-dihydroisoquinoline derivatives designed as tubulin polymerization inhibitors were synthesized. Their cytotoxic activities against the CEM leukemia cell line were evaluated. Most of them displayed moderate cytotoxic activities, and compounds 21 and 32 showed good activities with IC50 of 4.10 and 0.64 μM, respectively. The most potent compound 32 was further confirmed to be able to inhibit tubulin polymerization, and its hypothetical binding mode with tubulin was obtained by molecular docking.

  10. LSER model for organic compounds adsorption by single-walled carbon nanotubes: Comparison with multi-walled carbon nanotubes and activated carbon.

    Science.gov (United States)

    Yu, Xiangquan; Sun, Weiling; Ni, Jinren

    2015-11-01

    LSER models for organic compounds adsorption by single and multi-walled carbon nanotubes and activated carbon were successfully developed. The cavity formation and dispersion interactions (vV), hydrogen bond acidity interactions (bB) and π-/n-electron interactions (eE) are the most influential adsorption mechanisms. SWCNTs is more polarizable, less polar, more hydrophobic, and has weaker hydrogen bond accepting and donating abilities than MWCNTs and AC. Compared with SWCNTs and MWCNTs, AC has much less hydrophobic and less hydrophilic adsorption sites. The regression coefficients (e, s, a, b, v) vary in different ways with increasing chemical saturation. Nonspecific interactions (represented by eE and vV) have great positive contribution to organic compounds adsorption, and follow the order of SWCNTs > MWCNTs > AC, while hydrogen bond interactions (represented by aA and bB) demonstrate negative contribution. These models will be valuable for understanding adsorption mechanisms, comparing adsorbent characteristics, and selecting the proper adsorbents for certain organic compounds. PMID:26319510

  11. Stable Carbon Isotope Ratios of Phenolic Compounds in Secondary Particulate Organic Matter Formed by Photooxidation of Toluene

    CERN Document Server

    Irei, Satoshi; Huang, Lin; Auld, Janeen; Collin, Fabrice; Hastie, Donald

    2014-01-01

    Compound-specific stable carbon isotope ratios for phenolic compounds in secondary particulate organic matter (POM) formed by photooxidation of toluene were studied. Secondary POM generated by photooxidation of toluene using a continuous-flow reactor and an 8 cubic meter indoor smog chamber was collected, and then extracted with acetonitrile. Eight phenolic compounds were identified in the extracts by a gas chromatograph coupled with a mass spectrometer, and their compound-specific stable carbon isotope ratios were determined by a gas chromatograph coupled with a combustion furnace followed by an isotope ratio mass spectrometer. The majority of the products, including methylnitrophenols and methylnitrocatechols, were isotopically depleted by 5 to 6 permil compared to the initial isotope ratio for toluene, whereas the isotope ratio for 4_nitrophenol remained the same as the initial isotope ratio for toluene. Based on the reaction mechanisms postulated in literature, stable carbon isotope ratios of these produc...

  12. Effect of effluent organic matter on the adsorption of perfluorinated compounds onto activated carbon

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Jing [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210046 (China); College of Environmental Science and Engineering, Yangzhou University, 196 West Huayang Road, Yangzhou 225127 (China); Lv, Lu, E-mail: esellu@nju.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210046 (China); Lan, Pei [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210046 (China); College of Environmental Science and Engineering, Yangzhou University, 196 West Huayang Road, Yangzhou 225127 (China); Zhang, Shujuan [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210046 (China); Pan, Bingcai, E-mail: bcpan@nju.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210046 (China); Zhang, Weiming [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210046 (China)

    2012-07-30

    Highlights: Black-Right-Pointing-Pointer The presence of EfOM significantly reduced the adsorption capacities and rates of PFCs. Black-Right-Pointing-Pointer Low-molecular-weight EfOM compounds (<1 kDa) compete for adsorption sites of PFSs directly. Black-Right-Pointing-Pointer Large-molecular-weight EfOM compounds (>30 kDa) affect the adsorption through pore blockage or restriction effect. Black-Right-Pointing-Pointer Changes in surface properties of PAC caused by preloaded EfOM could affect PFCs adsorption. - Abstract: Effect of effluent organic matter (EfOM) on the adsorption of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) onto powdered activated carbon (PAC) was quantitatively investigated at environmentally relevant concentration levels. The adsorption of both perfluorinated compounds (PFCs) onto PAC followed pseudo-second order kinetics and fitted the Freundlich model well under the given conditions. Intraparticle diffusion was found to be the rate-controlling step in the PFC adsorption process onto PAC in the absence and presence of EfOM. The presence of EfOM, either in PFC-EfOM simultaneous adsorption onto fresh PAC or in PFC adsorption onto EfOM-preloaded PAC, significantly reduced the adsorption capacities and sorption rates of PFCs. The pH of zero point of charge was found to be 7.5 for fresh PAC and 4.2 for EfOM-preloaded PAC, suggesting that the adsorbed EfOM imparted a negative charge on PAC surface. The effect of molecular weight distribution of EfOM on the adsorption of PFCs was investigated with two EfOM fractions obtained by ultrafiltration. The low-molecular-weight compounds (<1 kDa) were found to be the major contributors to the significant reduction in PFC adsorption capacity, while large-molecular-weight compounds (>30 kDa) had much less effect on PFC adsorption capacity.

  13. Preparation and evaluation of the homogeneity of milk as a candidate reference material for carbon-14

    International Nuclear Information System (INIS)

    A pilot project was initiated to study the feasibility of preparing milk as a candidate reference material for 14C near environmental levels. Two materials, MK-B at natural level of 14C and MK-C4 at an elevated level, have been prepared from pasteurized 2% dairy milk. MK-C4 was spiked with an appropriate amount of 14C-methylated casein tracer to achieve the elevated level. Several samples from MK-B and MK-C4 have been analyzed to test the homogeneity of these materials for the distribution of 14C. The samples were combusted in oxygen under 20 atmospheres pressure using a Parr bomb. The 14C concentrations were determined by liquid scintillation counting using Carbo-Sorb/Permafluor E+ cocktail. The results indicate that these materials are homogeneous with respect to 14C concentration even in sub-sample sizes of 0.25 g of the freeze-dried material. The precision of our 14C measurements, as expressed by the % relative standard deviation, is within 5%. The accuracy has been tested by analyzing replicate samples of the IAEA 14C quality assurance materials, C-3 (cellulose) and C-6 (ANU sucrose) and found to be within 3%. The lower limits of detection are 0.08, 0.05 and 0.02 Bq.g-1 of carbon for 20 ml of liquid scintillation mixture (Carbo-Sorb/Permafluor E+ = ∼0.67) loaded with up to 0.4g of carbon from the sample and counted for 3 cycles of 60, 180 and 1000 min each, respectively. Our measurements of 14C specific activities of MK-B and MK-C4 are 0.26 ± 0.01 and 15.3 ± 0.4 Bq.g-1 of carbon, respectively. (author)

  14. Resolution of Adsorption and Partition Components of Organic Compounds on Black Carbons.

    Science.gov (United States)

    Chiou, Cary T; Cheng, Jianzhong; Hung, Wei-Nung; Chen, Baoliang; Lin, Tsair-Fuh

    2015-08-01

    Black carbons (BCs) may sequester non-ionic organic compounds by adsorption and/or partition to varying extents. Up to now, no experimental method has been developed to accurately resolve the combined adsorption and partition capacity of a compound on a BC. In this study, a unique "adsorptive displacement method" is introduced to reliably resolve the adsorption and partition components for a solute-BC system. It estimates the solute adsorption on a BC by the use of an adsorptive displacer to displace the adsorbed target solute into the solution phase. The method is validated by tests with uses of activated carbon as the model carbonaceous adsorbent, soil organic matter as the model carbonaceous partition phase, o-xylene and 1,2,3-trichlorobenzene as the reference solutes, and p-nitrophenol as the adsorptive displacer. Thereafter, the adsorption-partition resolution was completed for the two solutes on selected model BCs: four biochars and two National Institute of Standards and Technology (NIST) standard soots (SRM-2975 and SRM-1650b). The adsorption and partition components resolved for selected solutes with given BCs and their dependences upon solute properties enable one to cross-check the sorption data of other solutes on the same BCs. The resolved components also provide a theoretical basis for exploring the potential modes and extents of different solute uptakes by given BCs in natural systems. PMID:26114972

  15. Algal C-14 and total carbon metabolisms 2. Experimental observations with the diatom Skeletonema costatum

    DEFF Research Database (Denmark)

    Williams, P.J.L.; Robinson, C.; Søndergaard, M.; Jespersen, A.M.; Bentley, T.L.; Lefevre, D.; Richardson, Katherine; Riemann, B.

    1996-01-01

    Three sets of comparisons of net and gross inorganic carbon assimilation and C-14 uptake were made with an axenic culture of Skeletonema costatum. The comparisons showed that in the physiological window studied (10-20% of the intrinsic generation time and gross photosynthesis/respiration ratios of......2. The conclusion drawn was that over the time scale studied, the C-14 technique was measuring net photosynthesis, consistent with essentially 100% recycling of respiratory CO2. The study has shown that we now possess the basis to make a rigorous analysis of net, gross CO2 fixation and net C-14...

  16. Use of 14C-uniformly labelled maize for studying carbon mineralization and humification in three soils (oxisol, mollisol, Andosol

    International Nuclear Information System (INIS)

    Maize plants have been grown for 120 days in a 14CO2 atmosphere under controlled conditions. At the end of this period, the whole plants were dried after the roots have been removed from the substrate culture. The uniformity of labelling of plant materials was then checked by selective extractions. After nine weeks, no very significant differences appear between the total mineralized carbon originating from the different parts of the plants. But differences in mineralization rate were significant during the first two weeks, particularly for water-soluble extracts and even for stalks and leaves. Other results appear as radioactive and total carbon balance before and after incubation. Quite 30% of the added material was mineralized in the three soil samples after nine weeks. The clearest differences were evident in the humified fraction percentage. For instance, in the horizon of the typic Andosol, are the least light fraction and the greatest alkali-soluble humified compounds; this is also true for total carbon. Humus formation is proved to be strongly influenced by soil mineralogy and humus type

  17. 14.7% efficient mesoscopic perovskite solar cells using single walled carbon nanotubes/carbon composite counter electrodes

    Science.gov (United States)

    Li, Hao; Cao, Kun; Cui, Jin; Liu, Shuangshuang; Qiao, Xianfeng; Shen, Yan; Wang, Mingkui

    2016-03-01

    A single walled carbon nanotube (SWCNT) possesses excellent hole conductivity. This work communicates an investigation of perovskite solar cells using a mesoscopic TiO2/Al2O3 structure as a framework in combination with a certain amount of SWCNT-doped graphite/carbon black counter electrode material. The CH3NH3PbI3-based device achieves a power conversion efficiency of 14.7% under AM 1.5G illumination. Detailed investigations show an increased charge collection in this device compared to that without the SWCNT additive.A single walled carbon nanotube (SWCNT) possesses excellent hole conductivity. This work communicates an investigation of perovskite solar cells using a mesoscopic TiO2/Al2O3 structure as a framework in combination with a certain amount of SWCNT-doped graphite/carbon black counter electrode material. The CH3NH3PbI3-based device achieves a power conversion efficiency of 14.7% under AM 1.5G illumination. Detailed investigations show an increased charge collection in this device compared to that without the SWCNT additive. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07347b

  18. Recharge in northern clime calcareous sandy soils: soil water chemical and carbon-14 evolution

    International Nuclear Information System (INIS)

    Chemical analyses were performed on soil water extracted from two cores taken from a sandy calcareous soil near Delhi, Ontario. Calcite saturation is attained within the unsaturated zone over short distances and short periods of time, whereas dolomite undersaturation persists to the groundwater table. The progressive dissolution of dolomite by soil water, within the unsaturated zone, after calcite saturation is reached results in calcite supersaturation. Deposition of iron and manganese oxyhydroxide phases occurs at the carbonate leached/unleached zone boundary. This is a result of soil water neutralization due to carbonate dissolution during infiltration but may also reflect the increased rate of oxidation of dissolved ferrous and manganous ions at higher pH's. The role of bacteria in this process has not been investigated. The depth of the carbonate leached/unleached zone boundary in a calcareous soil has important implications for 14C groundwater dating. The depth of this interface at the study site (= approximately 2 m) does not appear to limit 14C diffusion from the root zone to the depth at which carbonate dissolution occurs. Thus, soil water achieves open system isotopic equilibrium with the soil CO2 gas phase. It is calculated that in soils with similar physical properties to the study soil but with depths of leaching of 5 m or more, complete 14C isotopic equilibration of soil water with soil gas would not occur. Soil water, under these conditions would recharge to the groundwater exhibiting some degree of closed system 14C isotopic evolution. (author)

  19. 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)

  20. Predicting adsorption of aromatic compounds by carbon nanotubes based on quantitative structure property relationship principles

    Science.gov (United States)

    Rahimi-Nasrabadi, Mehdi; Akhoondi, Reza; Pourmortazavi, Seied Mahdi; Ahmadi, Farhad

    2015-11-01

    Quantitative structure property relationship (QSPR) models were developed to predict the adsorption of aromatic compounds by carbon nanotubes (CNTs). Five descriptors chosen by combining self-organizing map and stepwise multiple linear regression (MLR) techniques were used to connect the structure of the studied chemicals with their adsorption descriptor (K∞) using linear and nonlinear modeling techniques. Correlation coefficient (R2) of 0.99 and root-mean square error (RMSE) of 0.29 for multilayered perceptron neural network (MLP-NN) model are signs of the superiority of the developed nonlinear model over MLR model with R2 of 0.93 and RMSE of 0.36. The results of cross-validation test showed the reliability of MLP-NN to predict the K∞ values for the aromatic contaminants. Molar volume and hydrogen bond accepting ability were found to be the factors much influencing the adsorption of the compounds. The developed QSPR, as a neural network based model, could be used to predict the adsorption of organic compounds by CNTs.

  1. Enhanced separation of Compound Xueshuantong capsule using functionalized carbon nanotubes with cationic surfactant solutions in MEEKC.

    Science.gov (United States)

    Cao, Jun; Li, Ping; Chen, Jue; Tan, Ting; Dai, Han-Bin

    2013-01-01

    A novel additive of multi-walled carbon nanotubes (MWNTs) dispersed with cationic surfactants or mixed cationic/anionic surfactants was used for MEEKC separation of eight phenolic compounds, four glycosides, and one phenanthraquinone. In this context, several parameters affecting MEEKC separation were studied, including the dispersion agents of MWNTs, MWNTs content, oil type, SDS concentration, and the type and concentration of cosurfactant. Compared with conventional MEEKC, the addition of all types of MWNTs dispersions using single or mixed cationic surfactant solutions in running buffers was especially useful for improving the separation of solutes tested, as they influenced the partitioning between the oil droplets and aqueous phase due to the exceptional electrical properties and large surface areas of MWNTs. Use of cationic surfactant-coated MWNTs (6.4 μg/mL) as the additive in a microemulsion buffer (0.5% octanol, 2.8% SDS, 5.8% isopropanol, and 5 mM borate buffer) yielded complete resolution of 13 analytes. The proposed method has been successfully applied for the detection and quantification of the studied compounds in a complex matrix sample (Compound Xueshuantong capsule). PMID:23161282

  2. Electrically Conductive Compounds of Polycarbonate, Liquid Crystalline Polymer, and Multiwalled Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Penwisa Pisitsak

    2012-01-01

    Full Text Available A thermotropic liquid crystalline polymer (LCP was blended with polycarbonate (PC and multiwalled carbon nanotube (CNT with the goal of improving electrical conductivity and mechanical properties over PC. The LCP was anticipated to produce fibrillar domains in PC and help improve the mechanical properties. The study was carried out using two grades of LCP—Vectra A950 (VA950 and Vectra V400P (V400P. The compounds contained 20 wt% LCP and 0.5 to 15 wt% CNT. The compounds were prepared by melt-blending in a twin-screw minicompounder and then injection molded using a mini-injection molder. The fibrillar domains of LCP were found only in the case of PC/VA950 blend. However, these fibrils turned into droplets in the presence of CNT. It was found that CNT preferentially remained inside the LCP domains as predicted from the value of spreading coefficient. The electrical conductivity showed the following order with the numbers in parenthesis representing the electrical percolation threshold of the compounds: PC/CNT (1% > PC/VA950P/CNT (1% > PC/V400P/CNT (3%. The storage modulus showed improvements with the addition of CNT and VA950.

  3. Removal of sulfur compounds from petroleum refinery wastewater through adsorption on modified activated carbon.

    Science.gov (United States)

    Ben Hariz, Ichrak; Al Ayni, Foued; Monser, Lotfi

    2014-01-01

    The adsorption of sulfur compounds from petroleum refinery wastewater on a chemically modified activated carbon (MAC) was investigated. The modification technique (nitric acid, hydrogen peroxide and thermal modification) enhanced the removal capacity of carbon and therefore decreases cost-effective removal of sulfide from refinery wastewater. Adsorption equilibrium and kinetics data were determined for sulfur removal from real refinery wastewater. The data were evaluated according to several adsorption isotherm and kinetics models. The Freundlich isotherm fitted well with the equilibrium data of sulfur on different adsorbents, whereas the kinetics data were best fitted by the pseudo-second-order model. Insights of sulfide removal mechanisms indicated that the sorption was controlled through the intraparticle diffusion mechanism with a significant contribution of film diffusion. The MAC adsorbent was found to have an effective removal capacity of approximately 2.5 times that of non-modified carbon. Using different MAC, sulfides were eliminated with a removal capacity of 52 mg g(-1). Therefore, MAC can be utilized as an effective and less expensive adsorbent for the reduction of sulfur in refinery wastewater. PMID:25353943

  4. Variation of 14C, 137Cs and stable carbon composition in forest soil and its implications

    International Nuclear Information System (INIS)

    In Japan, about 70% of land area is covered by forest. Therefore, forest ecosystem plays a vital role in ultimate fate of radionuclides and carbon cycle in terrestrial environment. Three undisturbed forest soil profiles were collected from Ibaraki Prefecture, Japan. The 137Cs data illustrate that maximum fallout deposition of 137Cs took place around 1964. 14C determination shows that 14C also has peak values in the top 10 cm of the soil profiles ascribed to the highest bomb 14C level in 1960's. The 13C data show that the turnover dynamics of soil organic carbon could be described very well by progressive enrichment values of δ13C. (author)

  5. Preparation of 14C-Labeled Multi-walled Carbon Nano-tubes for Biodistribution Investigations

    International Nuclear Information System (INIS)

    A new method allowing the 14C-labeling of carboxylic acid functions of carbon nano-tubes is described. The key step of the labeling process is a de-carbonylation reaction that has been developed and optimized with the help of a screening method. The optimized process has been successfully applied to multi-walled carbon nano-tubes (MWNTs), and the corresponding 14C-labeled nano-tubes were used to investigate their in vivo behavior. Preliminary results obtained after i.v. contamination of rats revealed liver as the main target organ. Radiolabeling of NTs with a long-life radioactive nucleus like 14C, coupled to a highly sensitive autoradiographic method, that provides a unique detection threshold, will make it possible to determine for a long time period whether or not NTs remain in any organs after animal exposure. (authors)

  6. Photosynthesis and assimilate partitioning characteristics of the coconut palm as observed by carbon-14 labelling

    International Nuclear Information System (INIS)

    A technique was developed on the use of carbon dioxide(carbon-14 labelled) rapid labelling of foliage and to ascertain photosynthesis and partitioning characteristics of labelled assimilate into other parts of the coconut palm. An eight-year-old Tall x Tall young coconut palm growing under field conditions at Bandirippuwa Estate and with six developing bunches , was selected for this study. The labelling was carried out on a bright sunny day and soil was at field capacity. Seventh leaf from the youngest open leaf was used for labelling with 5 mCi of sodium bi carbonate (Carbon-14 labelled). The results revealed that within 24 hours, 60% of the labelled assimilate was partitioned into other parts of the palm and at the end of the seventh day about 18% of the labelled assimilate still remained in the labelled leaf. Among the developing bunches fifth and sixth bunches from the youngest developing bunch received more labelled assimilate than young developing bunches above them. It was revealed that partitioning of assimilate into various ''sinks'' is determined by the developmental stage or activeness of the ''sink''. The proportion of C-14 labelled carbon assimilate, partitioned into developing bunches was substantially low compared to the total amount of labelled carbon fixed by the labelled leaf. Further, it was observed that partitioning of assimilated labelled carbon into the young leaves above, as well as the mature leaves below the labelled leaf. The complex vascular anatomy of the palms could be attributed to this pattern of partitioning of assimilates into upper and lower leaves from the labelled leaf

  7. The removal of endocrine disrupting compounds, pharmaceutically activated compounds and cyanobacterial toxins during drinking water preparation using activated carbon--a review.

    Science.gov (United States)

    Delgado, Luis F; Charles, Philippe; Glucina, Karl; Morlay, Catherine

    2012-10-01

    This paper provides a review of recent scientific research on the removal by activated carbon (AC) in drinking water (DW) treatment of 1) two classes of currently unregulated trace level contaminants with potential chronic toxicity-pharmaceutically activate compounds (PhACs) and endocrine disrupting compounds (EDCs); 2) cyanobacterial toxins (CyBTs), which are a group of highly toxic and regulated compounds (as microcystin-LR); and 3) the above mentioned compounds by the hybrid system powdered AC/membrane filtration. The influence of solute and AC properties, as well as the competitive effect from background natural organic matter on the adsorption of such trace contaminants, are also considered. In addition, a number of adsorption isotherm parameters reported for PhACs, EDCs and CyBTs are presented herein. AC adsorption has proven to be an effective removal process for such trace contaminants without generating transformation products. This process appears to be a crucial step in order to minimize PhACs, EDCs and CyBTs in finished DW, hence calling for further studies on AC adsorption removal of these compounds. Finally, a priority chart of PhACs and EDCs warranting further study for the removal by AC adsorption is proposed based on the compounds' structural characteristics and their low removal by AC compared to the other compounds. PMID:22885596

  8. High Carbon Use Efficiency is Not Explained by Production of Storage Compounds

    Science.gov (United States)

    Dijkstra, Paul; van Groenigen, Kees-Jan

    2015-04-01

    The efficiency with which microbes use substrate to make new microbial biomass (Carbon Use Efficiency or CUE; mol C / mol C) is an important variable in soil and ecosystem C cycling models. Estimates of CUE in soil microbial communities vary widely. It has been hypothesized that high values of CUE are associated with production of storage compounds following a sudden increases in substrate availability during CUE measurements. In that case, these high CUE values would not be representative for balanced microbial growth (i.e. the production of all compounds needed to make new microbial cells). To test this hypothesis, we added position-specific 13C-labeled glucose isotopomers in parallel incubations of a ponderosa pine and piñon-juniper soil. We compared the measured pattern of CO2 release for the six glucose C atoms with patterns of CO2 production expected for balanced growth with a low, medium, or high CUE, and with CO2 production patterns associated with production of storage compounds (glycogen, lipids, or polyhydroxybutyrate). The measured position-specific CO2 production did not match that for production of glycogen, lipids, or polyhydroxybutyrate, but agreed closely with that expected for balanced growth at high CUE and high pentose phosphate pathway activity. We conclude that soil microbial communities utilize glucose substrate for biomass growth with high CUE, and that addition of small amounts of 13C-labeled glucose tracers do not affect CUE or induce storage compounds production. We submit that the measurement of position-specific CO2 production offers a quick and easy way to test biochemically explicit hypotheses concerning microbial growth metabolism.

  9. Rare earths: preparation of spectro chemically pure standards, study of their carbonates and synthesis of a new compound series - the peroxy carbonates

    International Nuclear Information System (INIS)

    In this work the following studies are concerned: I) preparation of lanthanum, cerium, praseodymium, neodymium and samarium oxides for use as spectro chemically pure standards; II) behavior of the rare earth (La, Ce, Pr, Nd, Sm) carbonates soluble in ammonium carbonate and mixture of ammonium carbonate/ammonium hydroxide, and III) synthesis and characterization of rare earth peroxy carbonates - a new series of compounds. Data for the synthesis and characterization of the rare earths peroxy carbonates described for the first time in this work are presented and discussed. With the aid of thermal analysis (TG-DTG) the thermal stability and the stoichiometric composition for new compounds were established and a mechanism of thermal decomposition was proposed. The peroxy carbonate was prepared by the addition of hydrogen peroxyde to the complexed soluble rare earths carbonates. These studies included also the determinations of active oxygen, the total rare earth oxide by gravimetry and complexometry and the C, H and N contents by microanalysis. The new compounds were also investigated by infrared spectroscopy. (author)

  10. Physiological conditions and uptake of inorganic carbon-14 by plant roots

    International Nuclear Information System (INIS)

    The uptake of inorganic 14C by bean plant roots was measured. The plants were grown in a nutrient solution culture at pH 6 and a NaH14CO3 tracer was added to the growth medium. Photosynthesis and transpiration were varied by exposing the aerial portions of the plants to different atmospheric CO2 concentrations, humidities and light levels in a cuvette system. Leaf concentrations of 14C were measured at the end of the experiments using liquid scintillation counting. Plant uptake of 14C via the roots was independent of the photosynthetic rate and, in most cases, could be predicted by knowing the transpiration rate and the nutrient solution concentration. However, when a less efficient root-medium aeration system was used, 14C uptake was greater than that predicted using transpiration, a phenomenon observed by other researchers. This contrasted to results of another experiment where the measured uptake of iodine was much slower than that predicted using transpiration. Knowledge of transpiration rates is useful in predicting inorganic carbon uptake via the roots and in estimating 14C transport from contaminated soils to biota. Also, the independence of the uptake from photosynthesis and ambient CO2 concentrations suggests that future increases in atmospheric CO2 concentrations may not have a direct effect on root uptake of soil carbon. (author)

  11. Liquid-phase adsorption of multi-ring thiophenic sulfur compounds on carbon materials with different surface properties.

    Science.gov (United States)

    Zhou, Anning; Ma, Xiaoliang; Song, Chunshan

    2006-03-16

    This work examines the effects of structural and surface properties of carbon materials on the adsorption of benzothiophene (BT), dibenzothiophene (DBT), 4-methyldibenzothiophene (4-MDBT) and 4,6-dimethyl-dibenzothiophene (4,6-DMDBT) in the presence of 10 wt % of aromatics in liquid alkanes that simulate sulfur compounds in diesel fuels. The equilibrium-adsorption capacity varies significantly, from 1.7 to 7.0 mg-S/g-A. The results show that different carbon materials have significantly different sulfur-adsorption capacities and selectivities that depend not only on textural structure but also on surface functional groups. The adsorption of multi-ring sulfur compounds on carbon materials was found to obey the Langmuir isotherm. On the basis of adsorption tests and the characterization of carbon materials by BET and XPS, the oxygen-containing functional groups on the surface appear to play an important role in increasing sulfur-adsorption capacity. The adsorption-selectivity trend of the carbon materials for various compounds increases in the order of BT adsorption over nickel-based adsorbents. The regeneration of spent activated carbons was also conducted by solvent washing. The high-adsorption capacity and selectivity for methyl DBTs indicate that certain activated carbons are promising adsorbents for selective adsorption for removing sulfur (SARS) as a new approach to ultra deep desulfurization of diesel fuels. PMID:16526705

  12. Multiphase Carbon-14 Transport in a Near-Field-Scale Unsaturated Column of Natural Sediments

    Energy Technology Data Exchange (ETDEWEB)

    D. T. Fox; Mitchell A. Plummer; Larry C. Hull; D. Craig Cooper

    2004-03-01

    Wastes buried at the Subsurface Disposal Area (SDA) of the Idaho National Engineering and Environmental Laboratory include activated metals that release radioactive carbon-14 (14C) as they corrode. To better understand 14C phase partitioning and transport in the SDA sediments, we conducted a series of transport experiments using 14C (radio-labeled sodium carbonate) and nonreactive gas (sulfur hexafluoride) and aqueous (bromide and tritiated water) tracers in a large (2.6-m high by 0.9-m diameter) column of sediments similar to those used as cover material at the SDA. We established steady-state unsaturated flow prior to injecting tracers into the column. Tracer migration was monitored using pore-water and pore-gas samples taken from co-located suction lysimeters and gas ports inserted at ~0.3-m intervals along the column’s length. Measurements of 14C discharged from the sediment to the atmosphere (i.e., 14CO2 flux) indicate a positive correlation between CO2 partial pressure (pCO2) in the column and changes in 14CO2 flux. Though 14CO2 diffusion is expected to be independent of pCO2, changes of pCO2 affect pore water chemistry sufficiently to affect aqueous/gas phase 14C partitioning and consequently 14C2 flux. Pore-water and -gas 14C activity measurements provide an average aqueous/gas partitioning ratio, Kag, of 4.5 (±0.3). This value is consistent with that calculated using standard carbonate equilibrium expressions with measured pH, suggesting the ability to estimate Kag from carbonate equilibrium. One year after the 14C injection, the column was cored and solid-phase 14C activity was measured. The average aqueous/solid partition coefficient, Kd, (1.6 L kg-1) was consistent with those derived from small-scale and short-term batch and column experiments using SDA sediments, suggesting that bench-scale measurements are a valid means of estimating aqueous/solid partitioning at the much larger spatial scale considered in these meso-scale experiments. However

  13. Carbon-14 in waste packages for spent fuel in a tuff repository

    International Nuclear Information System (INIS)

    Carbon-14 is produced naturally by cosmic ray neutrons in the upper atmosphere. It is also produced in nuclear reactors, in amounts much smaller than the global inventory. About one-third of this is released directly to the atmosphere, and the other two-thirds remains in the spent fuel. Both the Environmental Protection Agency and the Nuclear Regulatory Commission have established limits on release of the 14C in spent fuel. This is of particular concern for the proposed repository in tuff, because of the unsaturated conditions and the consequent possibility of gaseous transport of 14C as CO2. Existing measurements and calculations of the 14C inventory in spent fuel are reviewed. The physical distribution and chemical forms of the 14C are discussed. Available data on the release of 14C from spent fuel in aqueous solutions and in gaseous environments of air, nitrogen, and helium are reviewed. Projected 14C behavior in a tuff repository is described. It is concluded that 14C release measurements from spent fuel into moist air at temperatures both above and below the in situ boiling point of water as well as detailed transport calculations for the tuff geological environment will be needed to determine whether the 10CFR60 and 40CFR191 requirements can be met. 56 refs., 1 tab

  14. Modelling the Environmental Transfer of Tritium and Carbon-14 to Biota and Man. Report of the Tritium and Carbon-14 Working Group of EMRAS Theme 1

    International Nuclear Information System (INIS)

    Hydrogen and carbon are biologically-regulated, essential elements that are highly mobile in the environment and the human body. As isotopes of these elements, tritium and 14C enter freely into water (in the case of tritium), plants, animals and humans. This complex behaviour means that there are substantial uncertainties in the predictions of models that calculate the transfer of tritium and 14C through the environment. The EMRAS Tritium/C14 Working Group (WG) was set up to establish the confidence that can be placed in the predictions of such models, to recommend improved modelling approaches, and to encourage experimental work leading to the development of data sets for model testing. The activities of the WG focused on the assessment of models for organically bound tritium (OBT) formation and translocation in plants and animals, the area where model uncertainties are largest. Environmental 14C models were also addressed because the dynamics of carbon and OBT are similar. The goals of the WG were achieved primarily through nine test scenarios in which model predictions were compared with observations obtained in laboratory or field studies. Seven of the scenarios involved tritium, covering terrestrial and aquatic ecosystems and steady-state and dynamic conditions. The remaining two scenarios concerned 14C, one addressing steady-state concentrations in plants and the other time-dependent concentrations in animals. The WG also considered one model intercomparison exercise involving the calculation of doses following a hypothetical, short-term release of tritium to the atmosphere in a farming area. Finally, the WG discussed the nature of OBT and proposed a definition to promote common understanding and usage within the international tritium community. The models used by the various participants varied in complexity from simple specific activity approaches to dynamic compartment models and process-oriented models, in which the various transfer processes were

  15. RT-MATRIX: Measuring Total Organic Carbon by Photocatalytic Oxidation of Volatile Organic Compounds

    Science.gov (United States)

    2008-01-01

    Volatile organic compounds (VOCs) inevitably accumulate in enclosed habitats such as the International Space Station and the Crew Exploration Vehicle (CEV) as a result of human metabolism, material off-gassing, and leaking equipment. Some VOCs can negatively affect the quality of the crew's life, health, and performance; and consequently, the success of the mission. Air quality must be closely monitored to ensure a safe living and working environment. Currently, there is no reliable air quality monitoring system that meets NASA's stringent requirements for power, mass, volume, or performance. The ultimate objective of the project -- the development of a Real-Time, Miniaturized, Autonomous Total Risk Indicator System (RT.MATRIX).is to provide a portable, dual-function sensing system that simultaneously determines total organic carbon (TOC) and individual contaminants in air streams.

  16. Some chemical synthesis of 14C labelled compounds of pharmaceutical or biological interest

    International Nuclear Information System (INIS)

    The recent discovery of the tuberculostatic properties of the hydrazide of isonicotinic acid (so-called 'Isoniazide', 'Rimifon') has raised considerably its interest, as for metabolic studies which it is more interesting to have it labelled with 14C. We describe in this report the chemical synthesis of 14C carboxyl labelled isoniazide which were done in the pyridine ring to highlight his metabolic function on the Koch's bacillus. (M.B.)

  17. Some chemical synthesis of {sup 14}C labelled compounds of pharmaceutical or biological interest

    Energy Technology Data Exchange (ETDEWEB)

    Pichat, I.; Baret, C.; Audinot, M.; Herbert, M.; Lambin, J. [Commissariat a l' Energie Atomique, Lab. du Fort de Chatillon, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1955-07-01

    The recent discovery of the tuberculostatic properties of the hydrazide of isonicotinic acid (so-called 'Isoniazide', 'Rimifon') has raised considerably its interest, as for metabolic studies which it is more interesting to have it labelled with {sup 14}C. We describe in this report the chemical synthesis of {sup 14}C carboxyl labelled isoniazide which were done in the pyridine ring to highlight his metabolic function on the Koch's bacillus. (M.B.)

  18. Algal C-14 and total carbon metabolisms 2. Experimental observations with the diatom Skeletonema costatum

    DEFF Research Database (Denmark)

    Williams, P.J.L.; Robinson, C.; Søndergaard, M.;

    1996-01-01

    of 2-3), C-14 uptake into the particulate plus the dissolved fractions approximated to net photosynthesis. Rate constants derived from the chemically determined changes were used to parameterize models that accounted for the respiration of photosynthetic products and for the recycling of respiratory CO......2. The conclusion drawn was that over the time scale studied, the C-14 technique was measuring net photosynthesis, consistent with essentially 100% recycling of respiratory CO2. The study has shown that we now possess the basis to make a rigorous analysis of net, gross CO2 fixation and net C-14......Three sets of comparisons of net and gross inorganic carbon assimilation and C-14 uptake were made with an axenic culture of Skeletonema costatum. The comparisons showed that in the physiological window studied (10-20% of the intrinsic generation time and gross photosynthesis/respiration ratios...

  19. A moderator ion exchange model to predict carbon-14 behaviour during operations

    International Nuclear Information System (INIS)

    Carbon-14 emissions from CANDU 6 stations are reduced through the removal of inorganic carbon ions by the ion exchange (IX) columns in the moderator purification system. A model has been developed to simulate the ion exchange behaviour of anions and cations present in the moderator. The model can be used to generate breakthrough curves for IX columns. Results from the program were compared to breakthrough curves generated by a small-scale experimental facility as well as data collected from Wolsong-3 where the IX column remained in service well past the recommended time. In both cases, the breakthrough curves were similar to the collected data. (author)

  20. The Synthesis of Imidazoline Derivative Compounds as Corrosion Inhibitor towards Carbon Steel in 1% NaCl Solution

    Directory of Open Access Journals (Sweden)

    Deana Wahyuningrum

    2008-03-01

    Full Text Available Oleic imidazoline is one of the nitrogen containing heterocyclic compounds that has been widely used as commercial corrosion inhibitor, especially in minimizing the carbon dioxide induced corrosion process in oilfield mining. In this present work, some imidazoline derivative compounds have been synthesized utilizing both conventional and microwave assisted organic synthesis (MAOS methods, in order to determine their corrosion inhibition properties on carbon steel surface. The MAOS method is more effective in synthesizing these compounds than the conventional method regarding to the higher chemical yields of products (91% to 94% and the shorter reaction times (7 to 10 minutes. The characterization of corrosion inhibition activities of the synthesized products towards carbon steel in 1% NaCl solution was determined by the Tafel plot method. The corrosion inhibition activities of compound 1b ((Z-2-(2-(heptadec-8-enyl-4,5-dihydroimidazol-1-ylethanamine, 2b ((Z-2-(2-(heptadec-8-enyl-4,5-dihydroimidazol-1-ylethanol and 3b (2-(2-heptadecyl-4,5-dihydroimidazol-1-ylethanamine at 8 ppm concentration in 1% NaCl solution are, respectively, 32.18%, 39.59% and 12.73%. The heptadec-8-enyl and hydroxyethyl substituents at C(2 and N(1 position of imidazoline ring, respectively, gave the most effective corrosion inhibition activity towards carbon steel compared to the presence of other substituents. The increase in concentrations of compound 1b, 2b and 3b in 1% NaCl solution tends to improve their corrosion inhibition activities. Based on the analysis of the free Gibbs adsorption energy (DG0ads values of compound 1b, 2b and 3b (-32.97, -34.34 and -31.27 kJ/mol, respectively, these compounds have the potential to interact with carbon steel through semi-physiosorption or semi-chemisorption.

  1. Poly(methyl methacrylate) and thiophene-coated single-walled carbon nanotubes for volatile organic compound discrimination

    Science.gov (United States)

    Muangrat, Worawut; Chodjarusawad, Thanawee; Maolanon, Rungroj; Pratontep, Sirapat; Porntheeraphat, Supanit; Wongwiriyapan, Winadda

    2016-02-01

    Poly(methyl methacrylate) (PMMA) and thiophene-coated single-walled carbon nanotubes (SWNTs) were fabricated for use in volatile organic compound (VOC) detection. Pristine SWNTs were separately coated with PMMA (PMMA/SWNTs) and thiophene (thiophene/SWNTs) by spin-coating. Pristine SWNTs showed the highest response to methanol, while PMMA/SWNTs enabled 5.4-fold improved dichloromethane detection and thiophene/SWNTs enabled 1.4-fold improved acetone detection compared with pristine SWNTs. The sensor response of PMMA/SWNTs to dichloromethane and that of thiophene/SWNTs to acetone can be attributed to the Hildebrand solubility parameter (HSP). The more similar the HSP, the higher the sensor response. The sensor response of pristine SWNTs to methanol is related to the diffusion coefficient and molecular size. The relationships between the vapor concentration and sensor response of PMMA/SWNTs to dichloromethane and thiophene/SWNTs to acetone are based on Henry’s adsorption isotherm, while that of pristine SWNTs to methanol is based on the Henry-clustering model. Principal component analysis (PCA) results show that dichloromethane, acetone, and methanol were successfully discriminated.

  2. Long-stored soil carbon released by prehistoric land use: Evidence from compound-specific radiocarbon analysis on Soppensee lake sediments

    Science.gov (United States)

    Gierga, Merle; Hajdas, Irka; van Raden, Ulrike J.; Gilli, Adrian; Wacker, Lukas; Sturm, Michael; Bernasconi, Stefano M.; Smittenberg, Rienk H.

    2016-07-01

    Compound-specific radiocarbon (14C) analyses allow studying the fate of individual biomarkers in ecosystems. In lakes with small catchments, terrestrial biomarkers have the potential to be used for the dating of sediments that lack the traditionally targeted terrestrial macrofossils, if the specific organic compounds are deposited soon after production. On the other hand, if the biomarkers have been stored for a significant amount of time in the soils of the catchment before transported to the lake, their age can be used to reconstruct changes in average residence time of organic material on land through time. Here we present a study based on compound-specific 14C analysis of the sedimentary record of Lake Soppensee, Switzerland, targeting long-chain n-alkanes of exclusive terrigenous origin, and comparing them with sediment ages obtained by high-resolution macrofossil dating. Additionally, we measured 14C ages of bulk organic matter and carbonate samples to assess the hard water effect. Prior to 3100 cal BP n-alkanes had about the same age as the sediment or they were slightly older, indicating that the vast majority of the terrestrial organic carbon transported to the lake had a short residence time on land. In the samples younger than 3100 cal BP an increasing offset is observed, indicating liberation of old buried soil organic matter that must have accumulated over the previous millennia. Our results indicate that as long as stable ecosystem conditions have prevailed, the distribution and isotopic composition of the n-alkanes can be used as environmental proxies in small catchments with limited surface runoff, confirming a few earlier studies.

  3. Reducing Emissions of Volatile Organic Compounds - Final Report - 08/15/1997 - 02/14/2001

    Energy Technology Data Exchange (ETDEWEB)

    Stensel, H. David; Strand, Stuart E.

    2001-03-14

    The overall objective of this research was to determine if the shallow suspended growth reactor (SSGR) could provide sufficient treatment performance of organic and reduced sulfur (TRS) compounds, at 50 C to meet the EPA ''cluster rule'' regulatory limits. The biodegradation of a mixture of organic compounds that could be present in pulp and paper high volume low concentration gas streams was evaluated at 50 C in a bench-scale SSGR. The removal of methanol was followed in particular, and was mathematically modeled to evaluate the effect of process design and operating parameters on methanol removal. Additional tests were performed to obtain mass transfer and biodegradation kinetic parameters for the model. The acclimation of microbial populations capable of degrading TRS compounds from various seed sources was studied in batch reactors at 30 and 50 C. The degradation of TRS compounds in bench-scale SSGR was studied at 20-50 C. Also, the biodegradation kinetic and mass transfer coefficients for alpha-terpinene and gamma-terpinene were studied. Finally, a pilot plant was constructed and operated at Simpson pulp and paper mill in Tacoma, WA.

  4. Pyrrolidine catalyzed reactions of cyclopentadiene with α,β-unsaturated carbonyl compounds: 1,2- versus 1,4-additions

    OpenAIRE

    Coskun, Necdet; Çetin, Meliha; Gronert, Scott; Ma, Jingxiang; Erden, Ihsan

    2015-01-01

    A systematic study of the reactions of cyclopentadiene with α,β-unsaturated carbonyl compounds in the presence of catalytic pyrrolidine-H2O revealed that the reactions can either proceed with a Michael attack at the β-carbon of enone, or 1,2-addition to the carbonyl, leadingeither to 4-cyclopentadienyl-2-butanones or 6-vinylfulvenes. The former can be isolated and/or converted to the corresponding 1,2-dihydropentalenes with base (or in one-pot at longer reaction times). Substitution pattern o...

  5. Local Field Effects in the Energy Transfer between a Chromophore and a Carbon Nanotube : a Single Nano-compound Investigation.

    OpenAIRE

    Roquelet, Cyrielle; Vialla, Fabien; Diederichs, Carole; Roussignol, Philippe; Delalande, Claude; Deleporte, Emmanuelle; Lauret, Jean-Sébastien; Voisin, Christophe

    2012-01-01

    Energy transfer in non-covalently bound porphyrin / carbon nanotube compounds is investigated at the single nano-compound scale. Excitation spectroscopy of the luminescence of the nanotube shows two resonances arising from intrinsic excitation of the nanotube and from energy transfer from the porphyrin. Polarization diagrams show that both resonances are highly anisotropic with a preferred direction along the tube axis. The energy transfer is thus strongly anisotropic despite the almost isotr...

  6. A Chlorine-36 and Carbon-14 Study of the Role of Chlorine in the Forest Ecosystem

    Czech Academy of Sciences Publication Activity Database

    Matucha, Miroslav; Gryndler, Milan; Forczek, Sándor; Schröder, P.; Bastviken, D.; Rohlenová, Jana; Uhlířová, H.; Fuksová, Květoslava

    2007-01-01

    Roč. 50, č. 1 (2007), s. 1-3. ISSN 0362-4803 R&D Projects: GA ČR GA522/02/0874; GA ČR GA526/05/0636 Institutional research plan: CEZ:AV0Z50380511 Keywords : [14C]-synthesis * labeled compounds * tetrahydrocyclopenta[b]indol-3-yl acetic acid Subject RIV: EF - Botanics Impact factor: 1.142, year: 2007

  7. Adsorption of volatile sulphur compounds onto modified activated carbons: effect of oxygen functional groups.

    Science.gov (United States)

    Vega, Esther; Lemus, Jesús; Anfruns, Alba; Gonzalez-Olmos, Rafael; Palomar, José; Martin, María J

    2013-08-15

    The effect of physical and chemical properties of activated carbon (AC) on the adsorption of ethyl mercaptan, dimethyl sulphide and dimethyl disulphide was investigated by treating a commercial AC with nitric acid and ozone. The chemical properties of ACs were characterised by temperature programme desorption and X-ray photoelectron spectroscopy. AC treated with nitric acid presented a larger amount of oxygen functional groups than materials oxidised with ozone. This enrichment allowed a significant improvement on adsorption capacities for ethyl mercaptan and dimethyl sulphide but not for dimethyl disulphide. In order to gain a deeper knowledge on the effect of the surface chemistry of AC on the adsorption of volatile sulphur compounds, the quantum-chemical COSMO-RS method was used to simulate the interactions between AC surface groups and the studied volatile sulphur compounds. In agreement with experimental data, this model predicted a greater affinity of dimethyl disulphide towards AC, unaffected by the incorporation of oxygen functional groups in the surface. Moreover, the model pointed out to an increase of the adsorption capacity of AC by the incorporation of hydroxyl functional groups in the case of ethyl mercaptan and dimethyl sulphide due to the hydrogen bond interactions. PMID:23708449

  8. Effect of effluent organic matter on the adsorption of perfluorinated compounds onto activated carbon.

    Science.gov (United States)

    Yu, Jing; Lv, Lu; Lan, Pei; Zhang, Shujuan; Pan, Bingcai; Zhang, Weiming

    2012-07-30

    Effect of effluent organic matter (EfOM) on the adsorption of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) onto powdered activated carbon (PAC) was quantitatively investigated at environmentally relevant concentration levels. The adsorption of both perfluorinated compounds (PFCs) onto PAC followed pseudo-second order kinetics and fitted the Freundlich model well under the given conditions. Intraparticle diffusion was found to be the rate-controlling step in the PFC adsorption process onto PAC in the absence and presence of EfOM. The presence of EfOM, either in PFC-EfOM simultaneous adsorption onto fresh PAC or in PFC adsorption onto EfOM-preloaded PAC, significantly reduced the adsorption capacities and sorption rates of PFCs. The pH of zero point of charge was found to be 7.5 for fresh PAC and 4.2 for EfOM-preloaded PAC, suggesting that the adsorbed EfOM imparted a negative charge on PAC surface. The effect of molecular weight distribution of EfOM on the adsorption of PFCs was investigated with two EfOM fractions obtained by ultrafiltration. The low-molecular-weight compounds (30kDa) had much less effect on PFC adsorption capacity. PMID:22609392

  9. Carbon-14 in neutron-irradiated graphite for graphite-moderated reactors. Joint research

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, Kimio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Matsuo, Hideto [Radioactive Waste Management and Nuclear Facility Decommissioning Technology Center, Tokyo (Japan)

    2002-12-01

    The graphite moderated gas cooled reactor operated by the Japan Atomic Power Company was stopped its commercial operation on March 1998, and the decommissioning process has been started. Graphite material is often used as the moderator and the reflector materials in the core of the gas cooled reactor. During the operation, a long life nuclide of {sup 14}C is generated in the graphite by several transmutation reactions. Separation of {sup 14}C isotope and the development of the separation method have been recognized to be critical issues for the decommissioning of the reactor core. To understand the current methodologies for the carbon isotope separation, literature on the subject was surveyed. Also, those on the physical and chemical behavior of {sup 14}C were surveyed. This is because the larger part of the nuclides in the graphite is produced from {sup 14}N by (n,p) reaction, and the location of them in the material tends to be different from those of the other carbon atoms. This report summarizes the result of survey on the open literature about the behavior of {sup 14}C and the separation methods, including the list of the literature on these subjects. (author)

  10. Measurement of pion double charge exchange on carbon-13, carbon-14, magnesium-26, and iron-56

    International Nuclear Information System (INIS)

    Cross sections for the /sup 13,14/C,26Mg,56Fe(π+,π-)/sup 13,14/O,26Si,56Ni reactions were measured with the Energetic Pion Channel and Spectrometer at the Clinton P. Anderson Meson Physics Facility for 120 less than or equal to T/sub π/ less than or equal to 292 MeV and 0 less than or equal to theta less than or equal to 50. The double isobaric analog states (DIAS) are of primary interest. In addition, cross sections for transitions to 14O(0+, 5.92 MeV), 14O(2+, 7.77 MeV), 56Ni(gs), 13O(gs), and 13O(4.21 MeV) are presented. The 13O(4.21 MeV) state is postulated to have J/sup π/ = 1/2-. The data are compared to previously measured double-charge-exchange cross sections on other nuclei, and the systematics of double charge exchange on T greater than or equal to 1 target nuclei leading to the DIAS are studied. Near the Δ33 resonance, cross sections for the DIAS transitions are in disagreement with calculations in which the reaction is treated as sequential charge exchange through the free pion-nucleon amplitude, while for T/sub π/ > 200 MeV the anomalous features of the 164 MeV data are not apparent. This is evidence for significant higher order contributions to the double-charge-exchange amplitude near the reasonable energy. Two theoretical approaches that include two nucleon processes are applied to the DIAS data. 64 references

  11. The synthesis of the insecticides Aldrin and Dieldrin labelled with carbon-14 at high specific activity

    International Nuclear Information System (INIS)

    Aldrin is the trade name given by Shell Chemicals to 1, 2, 3, 4, 10, 10-hexachloro-1, 4, 4a, 5, 8, 8a-hexahydro-exo-1, 4-endo-5, 8-dimethanonapthalene. Acetylene-1, 2-C14 is converted successively to tetrachloroethane and trichloroethylene, and this is condensed with carbon tetrachloride by the Prins reaction in the presence of aluminium chloride to octachlorocyclopentene. Dechlorination gives hexachlorocyclopentadiene which undergoes a Diels-Alder addition to bicyclo(2, 2, 1) hepta-2,5-diene to give aldrin-C14 in 12% yield from barium carbonate. Oxidation of Aldrin gives the 6,7 epoxide, Dieldrin, in 87% yield. The paper includes an account of the separation of octachlorocyclopentene from the crude product of the Prins reaction by gas-liquid chromatography and of the separation of Aldrin and Dieldrin on a small preparative scale by reversed-phase paper chromatography. (author)

  12. Carbon nanostructures as catalytic support for chemiluminescence of sulfur compounds in a molecular emission cavity analysis system.

    Science.gov (United States)

    Safavi, Afsaneh; Maleki, Norouz; Doroodmand, Mohammad Mahdi; Koleini, Mohammad Mehdi

    2009-06-30

    The effect of different substrates including stainless steel, activated carbon, single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), fullerenes (C60, C70, etc.) and SWCNTs doped with iron and palladium nanoparticles were compared for catalytic chemiluminescence reaction of sulfur compounds in a flame-containing cavity of molecular emission cavity analysis (MECA) system. Different forms of CNT substrates were fabricated using electric arc-discharge method. The blue emission of excited S2 was monitored using a CCD camera. The results demonstrate that, due to the high surface area, plenty of basal planes, high thermal conductivity, and high flexibility of the carbon nanostructure as appropriate support, carbon nanostructures play an important role in catalytic chemiluminescence emission of sulfur compounds in MECA. Moreover, the presence of metallic nanoparticles doped on carbon nanostructures enhances their catalytic effect. The results revealed that under similar conditions, SWCNTs/Pd doped nanoparticles, SWCNTs/Fe doped nanoparticles, SWCNTs, MWCNTs and fullerenes have the most catalytic effects on chemiluminescence of sulfur compounds, respectively. PMID:19463563

  13. Flux of carbon from 14C-enriched leaf litter throughout a forest soil mesocosm

    Energy Technology Data Exchange (ETDEWEB)

    Froberg, Mats J. [Sveriges Lantbruksuniversitet; Hanson, Paul J [ORNL; Trumbore, Susan E. [University of California, Irvine; Swanston, Christopher W. [USFS; Todd Jr, Donald E [ORNL

    2009-01-01

    The role of DOC for the build-up of soil organic carbon pools is still not well known, but it is thought to play a role in the transport of carbon to a greater depth where it becomes more stable. The aim of this study was to elucidate within-year dynamics of carbon transport from litter to the O (Oe and Oa) and A horizons. Mesocosms with constructed soil profiles were used to study dynamics of C transport from 14C-enriched (about 1000 ) leaf litter to the Oe/Oa and A horizons as well as the mineralization of leaf litter. The mesocosms were placed in the field for 17 months during which time fluxes and 14C content of DOC and CO2 were measured. Changes in 14C in leaf litter and bulk soil C pools were also recorded. Significant simultaneous release and immobilization of DOC occurring in both the O and A horizons was hypothesized. Contrary to our hypothesis, DOC released from the labeled Oi horizon was not retained within the Oe/Oa layer. DOC originating in the unlabeled Oe/Oa layer was also released for transport. Extensive retention of DOC occurred in the A horizon. DOC leaching from A horizon consisted of a mix of DOC from different sources, with a main fraction originating in the A horizon and a smaller fraction leached from the overlaying horizons. The C and 14C budget for the litter layer also indicated a surprisingly large amount of carbon with ambient Δ14C-signature to be respired from this layer. Data for this site also suggested significant contributions from throughfall to dissolved organic carbon (DOC) transport into and respiration from the litter layer. The results from this study showed that DOC retentionwas low in the O horizon and therefore not important for the O horizon carbon budget. In the A horizon DOC retention was extensive, but annual DOC input was small compared to C stocks and therefore not important for changes in soil C on an annual timescale.

  14. A method for monitoring mineralization of 14C-labeled compounds in aqueous samples

    International Nuclear Information System (INIS)

    Previously reported laboratory methods for measuring the rate of 14CO2 release from an aqueous sample require a series of replicate growth flasks. At chosen times, some of these are sacrificed in order to quantitate the 14CO2 released. The method presented here requires only one culture flask containing 200 ml of sample with labeled substrate, and one control-replacement flask containing 200 ml of sterile sample with labeled substrate. At each sampling time, 1/40th of the liquid and headspace gas is removed from the modified 500 ml Erlenmeyer culture flask for 14CO2 recovery. This method was used to study the mineralization of labeled amino acids, starch, n-hexadecane and anthracene by micro-organisms in river water, and of n-hexadecane and n-hexadecanoic acid by microorganisms in sewage effluent. (author)

  15. Crystal structure and magnetism of the Y2Pd14B5 compound

    International Nuclear Information System (INIS)

    The crystal structure of the ternary boride Y2Pd14B5, space group I41/amd, a=8.484(2) A, c=16.490(3) A, V=1186.98 A3, Z=4, was refined down to R=0.0475, wR2=0.1276 from single crystal X-ray diffraction data. Two types of coordination for boron atoms were observed: the coordination sphere for the B1 atom is a trigonal prism with one additional atom; the B2 atom has only four neighboring atoms which form a square. No boron-boron contact was observed. Analysis of the Y2Pd14B5 crystal structure shows the existence of a correlation between this structure and the Sc4Ni29B10 structure type. Magnetization and AC susceptibility measurements indicate that there is no superconducting or magnetic transition in Y2Pd14B5 down to 2 K

  16. Synthesis of 1-(4-methylsulfone-phenyl)-5-(4-fluoro-phenyl)-5-[14C]-1,2,3- triazole and 1-(4-sulfonamide-phenyl)-5-(4-fluoro-phenyl)-5-[14C]-1,2,3- triazole as novel carbon-14 anticonvulsant

    International Nuclear Information System (INIS)

    Two 1,2,3-triazole anticonvulsants, 1-(4-methylsulfone-phenyl)-5-(4-fluoro-phenyl)-5-[14C]-1,2,3-triazole and 1-(4-sulfonamide-phenyl)-5-(4- fluoro-phenyl)-5-[14C]-1,2,3-triazole, both labeled with carbon-14 in the 5-position were prepared from para-fluoro-benzonitrile-[cyano-14C]. (author)

  17. Benzopyrones. 14. Synthesis and antiallergic properties of some N-tetrazolylcarboxamides and related compounds.

    Science.gov (United States)

    Ellis, G P; Becket, G J; Shaw, D; Wilson, H K; Vardey, C J; Skidmore, I F

    1978-11-01

    A series of chromones containing an acidic group has been synthesized and screened for the ability to inhibit passive cutaneous anaphylaxis and the release of histamine from mast cells of the rat. Many of the chromones contain the N-(5-tetrazolyl)carboxamido group, a novel source of acidity. Others contain a carboxyl, C-(5-tetrazolyl), 5-(4H)-oxotetrazolinyl, or N-(5-tetrazolyl)sulfonamido function. The compounds were compared with cromolyn sodium (sodium cromoglycate) and many were found to be powerful inhibitors of anaphylaxis. The most potent was 7-methoxy-4-oxo-N-(5-tetrazolyl)-4H-1-benzopyran-2-carboxamide (15). Structure-activity relationships among the chromones and also some related compounds are discussed. PMID:82617

  18. Reexposure and advection of C-14-depleted organic carbon from old deposits at the upper continental slope

    OpenAIRE

    Tesi, Tommaso; Goñi, Miguel A.; Langone, Leonardo; Puig, Pere; Canals, Miquel; Nittrouer, Charles A.; Durrieu De Madron, Xavier; Calafat, Antoni; Palanques, Albert; Heussner, Serge; Davies, Maureen H.; Drexler, Tina M.; Fabres, Joan; Miserocchi, Stefano

    2010-01-01

    Outcrops of old strata at the shelf edge resulting from erosive gravity-driven flows have been globally described on continental margins. The reexposure of old strata allows for the reintroduction of aged organic carbon (OC), sequestered in marine sediments for thousands of years, into the modern carbon cycle. This pool of reworked material represents an additional source of C-14-depleted organic carbon supplied to the ocean, in parallel with the weathering of fossil organic carbon delivered ...

  19. Carbon-14 immobilization via the CO2-Ba(OH)2 hydrate gas-solid reaction

    International Nuclear Information System (INIS)

    Although no restrictions have been placed on the release of carbon-14, it has been identified as a potential health hazard due to the ease in which it may be assimilated into the biosphere. The intent of the Carbon-14 Immobilization Program, funded through the Airborne Waste Program Management Office, is to develop and demonstrate a novel process for restricting off-gas releases of carbon-14 from various nuclear facilities. The process utilizes the CO2-Ba(OH)2 hydrate gas-solid reaction to directly remove and immobilize carbon-14. The reaction product, BaCO3, possesses both the thermal and chemical stability desired for long-term waste disposal. The process is capable of providing decontamination factors in excess of 1000 and reactant utilization of greater than 99% in the treatment of high volumetric, airlike (330 ppM CO2) gas streams. For the treatment of an air-based off-gas stream, the use of packed beds of Ba(OH)2.8H2O flakes to remove CO2 has been demonstrated. However, the operating conditions must be maintained between certain upper and lower limits with respect to the partial pressure of water. If the water vapor pressure in the gas is less than the dissociation vapor pressure of Ba(OH)2.8H2O, the bed will deactivate. If the vapor pressure is considerably greater, pressure drop problems will increase with increasing humidity as the particles curl and degrade. Results have indicated that when operated in the proper regime, the bulk of the increase in pressure drop results from the conversion of Ba(OH)2.8H2O to BaCO3 and not from the hydration of the commercial Ba(OH)2.8H2O (i.e. Ba(OH)2.7.50H2O) to Ba(OH)2.8H2O

  20. Dating by C14

    International Nuclear Information System (INIS)

    This report summarizes the results of studies made with two assemblies for dating geological and archaeological objects with C14. The advantages and drawbacks of three ways of determining C14 activity in solid, liquid and gaseous substances are discussed. Data are given of the chemical preparation and cleaning of the gaseous carbon compounds ethane, acetylene and carbon dioxide, and the calculation of their C14 activity. The report assesses the mistakes that can be made in determining age by C14, and gives data for geological and archaeological objects in the Soviet Union. (author)

  1. Simulation of groundwater flow in the Voltaian (around Tamale) using carbon-14

    International Nuclear Information System (INIS)

    Studying the process of groundwater flow in subsurface systems using numerical simulation has been widely practiced. The purpose of this study was to establish a 2D groundwater flow model for evaluating groundwater resources of the Voltaian Basin (around Tamale) in the Northern Region of Ghana. To understand the rate of abstraction of groundwater in the study area, a finite-element, steady-state groundwater flow model was used to simulate groundwater flow in the aquifer. COMSOL Multiphysics' (FEMLAB) Earth Science Module (ESM) package which is finite element analysis and solver software was used. The radioisotope used in the study was Carbon-14. Three wells were sampled for Carbon-14 concentration and used for the model verification, based on elevation. From the results, groundwater in the study area moves generally from higher to lower hydraulic head along paths perpendicular to the equipotential lines. The groundwater flow paths in the aquifer in the study area indicated that flow is predominantly regional. There was a regional groundwater flow from Kashegu to Nawuni. Kanshegu appears to be recharge area and Nawuni as discharge area. The flow rate obtained using Carbon-14 date was 2.86×10-7 m/s. The overall flow rate obtained from the model simulations was 2.66×10-7 m/s with an error margin of 6%. (author)

  2. The use of barytocalcite for carbon 14 immobilization: One-year leaching behavior

    International Nuclear Information System (INIS)

    The spent nuclear fuel reprocessing process is one of the anthropogenic sources of carbon-14, and since this element is highly mobile in the geosphere, its sequestration is necessary. Several phases and industrial solutions to immobilize this radionuclide have been studied, including the barytocalcite phase BaCa(CO3)2 at 8.08 wt.% of C, which has many advantages such as its low specific volume of carbon. Recently, different options to synthesize this phase have been reported. Here we report on the aqueous durability of barytocalcite, studied for one year with pure water at 30 °C, in order to complete the behavior studies. Unexpected leaching behavior was encountered: it had been supposed that barytocalcite would only leach slowly, but after 1 year, it was no longer present. It appears that its simple CaCO3 and BaCO3 constituents precipitated, though the overall carbon loss was low during the period studied. This research gives a new insight into the behavior of this phase regarding carbon-14 immobilization

  3. Measurement of the carbon 14 activity at natural level in air samples

    International Nuclear Information System (INIS)

    The aim of the study was to measure the carbon 14 activity at natural level in air samples using classical methods of radiochemistry and beta counting. Three different methods have been tested in order to minimise the detection limit. In the three methods, the first step consists in trapping the atmospheric carbon 14 into NaOH (1N) using a bubbling chamber. The atmospheric carbon dioxide reacts with NaOH to form Na2CO3. In the first method the Na2CO3 solution is mixed with a liquid scintillate and is directly analysed by liquid scintillation counting (LSC). The detection limit is approximately 1 Bq/m3 of air samples. The second method consists in evaporating the carbonate solution and then counting the solid residue with a proportional gas circulation counter. The detection limit obtained is lower than the first method (0.4 Bq/m3 of air samples). In the third method, Na2CO3 is precipitated into CaCO3 in presence of CaCl2. CaCO3 is then analysed by LSC. This method appear to be the most appropriate, the detection limit is 0.05 Bq/m3 of air samples. (author)

  4. Relationship between carbon-14 concentrations in atmospheric CO2 and environmental samples

    International Nuclear Information System (INIS)

    Concentration of organically-bound 14C in the tree-ring cellulose of a pine tree grown in Shika-machi (37.1degN, 136.5degE), Ishikawa prefecture, Japan, was measured for the ring-years from 1949 to 1999 and compared with those in several trees from East Asia region reported by other researchers. Temporal variation of organically-bound 14C concentration in the tree-ring cellulose in Shika-machi showed essentially similar variations to those of other reports. However, small difference of Δ14C values was found during the period of 1970-1981 between our data and those of other reports, in addition to the difference during the period of 1963-1967 caused by the so-called latitude dependence of the 14C variations in the northern troposhere. These results suggest that the 14C concentration in atmospheric CO2 was considerably disturbed during the period of 1970-1981, especially in 1970, 1976, and 1978-1981, in the East Asia region. This phenomenon may be interpreted by the possibility of the several times of injections of 14C originated from a series of Chinese thermonuclear bomb tests. Temporal variation of 14C concentration in atmospheric CO2 in Kanazawa city, Ishikawa prefecture, Japan (36.3degN, 136.4degE), was also measured during the period of 1991-1999. An interesting result in comparing 14C concentrations in the tree-ring cellulose with those of atmospheric CO2 is that each of 14C concentrations in a series of tree rings reflected summer means of 14C concentrations in atmospheric CO2. It suggests that the carbon necessary for synthesizing tree-ring cellulose was mainly supplied from atmospheric CO2 in summer season. It is noteworthy that surface soils collected from different sites were found to demonstrate extremely low 14C concentrations than atmospheric CO2. It may be ascribed to the slow exchange rate of carbon between soils and atmospheric CO2. (author)

  5. Chemical Characterization and Removal of Carbon-14 from Irradiated Graphite II - 13023

    International Nuclear Information System (INIS)

    Approximately 250,000 tonnes of irradiated graphite waste exists worldwide and that quantity is expected to increase with decommissioning of Generation II reactors and deployment of Generation IV gas-cooled, graphite moderated reactors. This situation indicates the need for a graphite waste management strategy. Of greatest concern for long-term disposal of irradiated graphite is carbon-14 (C-14), with a half-life of 5730 years. Study of irradiated graphite from some nuclear reactors indicates C-14 is concentrated on the outer 5 mm of the graphite structure. The aim of the research presented last year and updated here is to identify the chemical form of C-14 in irradiated graphite and develop a practical method by which C-14 can be removed. A nuclear-grade graphite, NBG-18, and a high-surface-area graphite foam, POCOFoamR, were exposed to liquid nitrogen (to increase the quantity of C-14 precursor) and neutron-irradiated (1013 neutrons/cm2/s). Finer grained NBG-25 was not exposed to liquid nitrogen prior to irradiation at a neutron flux on the order of 1014 /cm2/s. Characterization of pre- and post-irradiation graphite was conducted to determine the chemical environment and quantity of C-14 and its precursors via the use of surface sensitive characterization techniques. Scanning Electron Microscopy (SEM) was used to evaluate the morphological features of graphite samples. The concentration, chemical composition, and bonding characteristics of C-14 and its precursors were determined through X-ray Photoelectron Spectroscopy (XPS), Time-of-Flight Secondary Ion Mass Spectrometry (SIMS), and Energy Dispersive X-ray Analysis Spectroscopy (EDX). Results of post-irradiation characterization of these materials indicate a variety of surface functional groups containing carbon, oxygen, nitrogen and hydrogen. During thermal treatment, irradiated graphite samples are heated in the presence of an inert carrier gas (with or without oxidant gas), which carries off gaseous products

  6. A study of the levels and distribution of carbon-14 and iodine-129 in the Irish marine and terrestrial environment

    International Nuclear Information System (INIS)

    The Sellafield nuclear fuel reprocessing plant is considered to be the largest single source of global anthropogenic carbon-14 discharge, as well as a substantial source of iodine-129. This study addresses the effects of these releases on the Irish coastal marine environment. In particular, spatial trends in the carbon-14 content of seaweed (Fucus spp.) were assessed by collecting and analysing samples from well-distributed locations around the Irish coastline. Temporal trends were studied by comparing carbon-14 concentrations in present-day samples with levels found in archive material collected at the same locations during research campaigns conducted in the mid-1980s and mid-1990s. Contamination by carbon-14 discharged from Sellafield was most evident in seaweeds from the northeastern Irish coast. This indicates that the pattern of residual currents and, in particular, the south to north transfer of water known to predominate in the Irish Sea, largely controls the spatial distribution of carbon-14 releases. Maximum carbon-14 discharge levels to the marine environment from Sellafield were mirrored by peak concentrations found in seaweed from the mid-1990s and in present-day samples. Concentrations of carbon-14 in seaweed from the west coast of Ireland correspond closely with values measured for seaweeds from the Atlantic coast of northwest Spain and do not appear to be significantly affected by Sellafield discharges

  7. Activation of the carbon-fluorine bonds in coordination compounds; Activacion de enlaces carbon-fluor en compuestos de coordinacion

    Energy Technology Data Exchange (ETDEWEB)

    Torrens, H. [Universidad Nacional Autonoma de Mexico, Facultad de Quimica, 04510 Mexico D.F. (Mexico)

    2000-07-01

    Activation of the carbon-fluorine bond is of upmost importance in several chemical processes. In search of synthetic alternatives to promote C-F bond cleavage in arylic systems, several square planar palladium and platinum compounds bearing fluorothiolates and fluorophosphines have been studied. In this paper molecular structures are shown for the following compounds trans-((SC{sub 6}F{sub 5})(P(C{sub 6}F{sub 5}){sub 2}(C{sub 6}H{sub 5}))(Pd({mu}-SC{sub 6}F{sub 5}){sub 2} Pd(SC{sub 6}F{sub 5})(P(C{sub 6}F{sub 5}){sub 2} (C{sub 6}H{sub 5})), cis ((SC{sub 6}F{sub 5}) P(C{sub 6}F{sub 5}){sub 2} (C{sub 6}H{sub 5}) Pt({mu}-SC{sub 6}F{sub 5}){sub 2} Pt(SC{sub 6}F{sub 5}) P(C{sub 6}F{sub 5}){sub 2} (C{sub 6}H{sub 5})), trans Pd ({mu}-SC{sub 6}F{sub 5}){sub 2} Pt(SC{sub 6}F{sub 5})(P(C{sub 6}F{sub 5})(C{sub 6}H{sub 5}){sub 2})), Pt (SC{sub 6}F{sub 5}){sub 2} (C{sub 6}F{sub 5}SC{sub 6}F{sub 4} P(C{sub 6}H{sub 5}){sub 2}))((SC{sub 6}F{sub 5}){sub 2} Pt ({mu}-(SC{sub 6}F{sub 5}){sub 2} Pt(SC{sub 6}F{sub 5}){sub 2}){sup 2-} , (SC{sub 6}HF{sub 4}){sub 2} Pt({mu}-SC{sub 6}HF{sub 4}){sub 2} Pt(SC{sub 6}HF{sub 4}){sub 2}){sup 2-} and ((SC{sub 6}F{sub 4}CF{sub 3}-4){sub 2} Pt (SC{sub 6}F{sub 4}CF{sub 3}-4){sub 2}){sup 2-} . (Author)

  8. An assessment of the inventory of Carbon-14 in the oceans

    International Nuclear Information System (INIS)

    The oceanic inventory for natural 14C is 19.6x1029 atoms, an estimate similar to those found by other methods. The 14C produced from nuclear weapons (1972) is 550x1026 atoms and 52% was in the oceans. From 1972 to 1985 132x1026 atoms of bomb 14C were added. The nuclear power industry produces 0.5x1026 atoms per year (17% of natural production rate). Most estimates by varying methods indicate an exchange time of carbon from atmosphere to ocean of about seven years or about 22 moles m-2 yr-1 for the surface ocean. The oceanic distribution generally has higher concentrations in low to mid latitudes, and low concentrations in the most southern regions, with the deep ocean retaining levels similar to those before nuclear testing

  9. 14C Activity and Global Carbon Cycle Changes over the Past 50,000 Years

    Science.gov (United States)

    Hughen, K.; Lehman, S.; Southon, J.; Overpeck, J.; Marchal, O.; Herring, C.; Turnbull, J.

    2004-01-01

    A series of 14C measurements in Ocean Drilling Program cores from the tropical Cariaco Basin, which have been correlated to the annual-layer counted chronology for the Greenland Ice Sheet Project 2 (GISP2) ice core, provides a high-resolution calibration of the radiocarbon time scale back to 50,000 years before the present. Independent radiometric dating of events correlated to GISP2 suggests that the calibration is accurate. Reconstructed 14C activities varied substantially during the last glacial period, including sharp peaks synchronous with the Laschamp and Mono Lake geomagnetic field intensity minimal and cosmogenic nuclide peaks in ice cores and marine sediments. Simulations with a geochemical box model suggest that much of the variability can be explained by geomagnetically modulated changes in 14C production rate together with plausible changes in deep-ocean ventilation and the global carbon cycle during glaciation.

  10. Source terms; isolation and radiological consequences of carbon-14 waste in the Swedish SFR repository

    International Nuclear Information System (INIS)

    The source term, isolation capacity, and long-term radiological exposure of 14C from the Swedish underground repository for low and intermediate level waste (SFR) is assessed. The prospective amount of 14C in the repository is assumed to be 5 TBq. Spent ion exchange resins will be the dominant source of 14C. The pore water in the concrete repository is expected to maintain a pH of >10.5 for a period of at least 106 y. The cement matrix of the repository will retain most of the 14CO32- initially present. Bacterial production of CO2 and CH4 from degradation of ion-exchange resins and bitumen may contribute to 14C release to the biosphere. However, CH4 contributes only to a small extent to the overall carbon loss from freshwater ecosystems. The individual doses to local and regional individuals peaked with 5x10-3 and regional individuals peaked with 5x10-3 and 8x10-4 μSv y-1 respectively at about 2.4x104 years. A total leakage of 8.4 GBq of 14C from the repository will cause a total collective dose commitment of 1.1 manSv or 130 manSv TBq-1. (authors)

  11. Analysis of hydrogen, carbon, sulfur and volatile compounds in (U{sub 3}Si{sub 2} - Al) nuclear fuel

    Energy Technology Data Exchange (ETDEWEB)

    Moura, Sergio C.; Redigolo, Marcelo M.; Amaral, Priscila O.; Leao, Claudio; Oliveira, Glaucia A.C. de; Bustillos, Oscar V., E-mail: ovega@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    Uranium silicide U{sub 3}Si{sub 2} is used as nuclear fuel in the research nuclear reactor IEA-R1 at IPEN/CNEN, Sao Paulo, Brazil. The U{sub 3}Si{sub 2} is dispersed in aluminum reaching high densities of uranium in the nucleus of the fuel, up to 4.8 gU cm{sup -3}. This nuclear fuel must comply with a quality control, which includes analysis of hydrogen, carbon and sulfur for the U{sub 3}Si{sub 2} and volatile compound for the aluminum. Hydrogen, carbon and sulfur are analyzed by the method of Radio Frequency gas extraction combustion coupled with Infrared detector. Volatile compounds are analyzed by the method of heated gas extraction coupled with gravimetric measurement. These methods are recommended by the American Society for Testing Materials (ASTM) for nuclear materials. The average carbon and sulfur measurements are 30 μg g{sup -1} and 3 μg g{sup -1}, respectively, and 40 μg g{sup -1} for volatile compounds. The hydrogen analyzer is a TCHEN 600 LECO, carbon and sulfur analyzer is a CS 244 LECO and the volatile compounds analyzer is a home-made apparatus that use a resistant furnace, a gas pipe measurement and a glove-box with controlled atmosphere where an analytical balance has been installed, this analyzer was made at IPEN laboratory. (author)

  12. Determination of the migration of a plasticizer by 14C-labelled compounds

    International Nuclear Information System (INIS)

    The migration rate of a plasticizer (dioctyl phthlate 14C) from a P.V.C. film, with different media in contact with it, was determined by measurements of radioactivity in the extraction liquids. Mineral oil, vegetal, oil aliphatic hidrocarbon and detergent solution were used for this purpose. The resulting figures were compared to those obtained from weight loss determinations and in some cases the percentage of ''swelling'' of the plastic could be established. (author)

  13. Synthesis of carbon C-14 labelled 2-phenyl-4-alpha-alkylaminomethyl-quinolinemethanol: a potential anti-leishmaniasis agent

    Energy Technology Data Exchange (ETDEWEB)

    Wang, T.S.T.; Fawwaz, R.A.; Heertum, R.L.van [Columbia Univ., New York, NY (United States). Coll. of Physicians and Surgeons

    1995-07-01

    Using sodium acetate, [1-{sup 14}C] as a starting material, a total of seven steps were required to synthesize the title compound. This involved acylation of ortho-dichlorobenzene to form dichloroacetophenone, [2-{sup 14}C] (I). The 2-phenyl-4-quinoline carboxylic acid, [2-{sup 14}C] (II) was prepared by the Pfitzinger reaction from (1) and dichloroisatin. Compound 11 was converted to the acid chloride (III) by reaction with SOCl{sub 2} in benzene. Grignard condensation reaction of (III) yielded 4-quinolylmethylketone, [2-{sup 14}C] (IV) which was then converted to the bromomethylketone (V). Compound V was reacted with NaBH{sub 4} to form the ethylene oxide (VI). Alkylation of the oxide yielded the title compound (VII). The overall radiochemical yield was 10.1% and the specific activity was 3.0 mCi/mmol, with a radiochemical purity of >99.5%. (author).

  14. Synthesis of carbon C-14 labelled 2-phenyl-4-alpha-alkylaminomethyl-quinolinemethanol: a potential anti-leishmaniasis agent

    International Nuclear Information System (INIS)

    Using sodium acetate, [1-14C] as a starting material, a total of seven steps were required to synthesize the title compound. This involved acylation of ortho-dichlorobenzene to form dichloroacetophenone, [2-14C] (I). The 2-phenyl-4-quinoline carboxylic acid, [2-14C] (II) was prepared by the Pfitzinger reaction from (1) and dichloroisatin. Compound 11 was converted to the acid chloride (III) by reaction with SOCl2 in benzene. Grignard condensation reaction of (III) yielded 4-quinolylmethylketone, [2-14C] (IV) which was then converted to the bromomethylketone (V). Compound V was reacted with NaBH4 to form the ethylene oxide (VI). Alkylation of the oxide yielded the title compound (VII). The overall radiochemical yield was 10.1% and the specific activity was 3.0 mCi/mmol, with a radiochemical purity of >99.5%. (author)

  15. Proportion of biogenic carbon in flue gas by carbon-14 measurement

    International Nuclear Information System (INIS)

    The subject of this project is closely related to EU's emissions trading system and to the current and future monitoring needs therein. The determination of fossil part of emissions originated from various fuels by stack measurements or by laboratory analyses could possibly find users also in other fields outside the ETS (e.g. waste incineration). After the market analysis and preliminary measurements carried out in the previous Biocarbon project this project focused on the development of the sampling method for stack measurements and to the validation of isotope measurements. The results obtained for fossil proportion of the fuel by current methods will be compared to those obtained by isotope measurements. The operation of the sampling system was tested in long period tests in plant conditions. Moreover, the sample preparation methods and isotope measurements were validated by measuring the proportions of biogenic and fossil carbon of known traffic fuel mixtures. The developed service concept can also be utilised as a fraud prevention measure related to the expanding international biofuels-trade. (orig.)

  16. Photocatalytic and chemical oxidation of organic compounds in supercritical carbon dioxide. 1998 annual progress report

    International Nuclear Information System (INIS)

    'This report summarizes the results of work done during the first 1.3 years of a three year project. During the first nine months effort focussed on the design, construction and testing of a closed recirculating system that can be used to study photochemistry in supercritical carbon dioxide at pressures up to 5,000 psi and temperatures up to about 50 C. This was followed by a period of work in which the photocatalytic oxidation of benzene and acetone in supercritical, liquid, and gaseous carbon dioxide containing dissolved oxygen was demonstrated. The photocatalyst was titanium dioxide supported on glass spheres. This was the first time it was possible to observe photocatalytic oxidation in a supercritical fluid and to compare reaction in the three fluid phases of a solvent. This also demonstrated that it is possible to purify supercritical and liquid carbon dioxide using photochemical oxidation with no chemical additions other than oxygen. The oxidation of benzene produced no intermediates detectable using on line spectroscopic analysis or by gas chromatographic analysis of samples taken from the flow system. The catalyst surface did darken as the reaction proceeded indicating that oxidation products were accumulating on the surface. This is analogous to the behavior of aromatic compounds in air phase photocatalytic oxidation. The reaction of acetone under similar conditions resulted in the formation of low levels of by-products. Two were identified as products of the reaction of acetone with itself (4-methyl-3-penten-2-one and 4-hydroxy-4-methyl-2-pentanone) using gas chromatography with a mass spectrometer detector. Two other by-products also appear to be from the self-reaction of acetone. By-products of this type had not been observed in prior studies of the gas-phase photocatalytic oxidation of acetone. The by-products that have been observed can also be oxidized under the treatment conditions. The above results establish that photocatalytic oxidation of

  17. Adsorption of volatile sulphur compounds onto modified activated carbons: Effect of oxygen functional groups

    International Nuclear Information System (INIS)

    Highlights: • HNO3 oxidation incorporates a higher amount of functionalities than O3 oxidation. • The loss of porosity is compensated by the massive incorporation of oxygen groups. • HNO3 oxidation increases OH groups in AC and the ETM and DMS adsorption capacities. • The oxygen functional groups in the AC surface did not affect the DMDS adsorption. • COSMO-RS predicts the important role of OH groups for VSC adsorption. -- Abstract: The effect of physical and chemical properties of activated carbon (AC) on the adsorption of ethyl mercaptan, dimethyl sulphide and dimethyl disulphide was investigated by treating a commercial AC with nitric acid and ozone. The chemical properties of ACs were characterised by temperature programme desorption and X-ray photoelectron spectroscopy. AC treated with nitric acid presented a larger amount of oxygen functional groups than materials oxidised with ozone. This enrichment allowed a significant improvement on adsorption capacities for ethyl mercaptan and dimethyl sulphide but not for dimethyl disulphide. In order to gain a deeper knowledge on the effect of the surface chemistry of AC on the adsorption of volatile sulphur compounds, the quantum-chemical COSMO-RS method was used to simulate the interactions between AC surface groups and the studied volatile sulphur compounds. In agreement with experimental data, this model predicted a greater affinity of dimethyl disulphide towards AC, unaffected by the incorporation of oxygen functional groups in the surface. Moreover, the model pointed out to an increase of the adsorption capacity of AC by the incorporation of hydroxyl functional groups in the case of ethyl mercaptan and dimethyl sulphide due to the hydrogen bond interactions

  18. Carbon based secondary compounds do not provide protection against heavy metal road pollutants in epiphytic macrolichens.

    Science.gov (United States)

    Gauslaa, Yngvar; Yemets, Olena A; Asplund, Johan; Solhaug, Knut Asbjørn

    2016-01-15

    Lichens are useful monitoring organisms for heavy metal pollution. They are high in carbon based secondary compounds (CBSCs) among which some may chelate heavy metals and thus increase metal accumulation. This study quantifies CBSCs in four epiphytic lichens transplanted for 6months on stands along transects from a highway in southern Norway to search for relationships between concentrations of heavy metals and CBSCs along a gradient in heavy metal pollutants. Viability parameters and concentrations of 21 elements including nutrients and heavy metals in these lichen samples were reported in a separate paper. Medullary CBSCs in fruticose lichens (Ramalina farinacea, Usnea dasypoga) were reduced in the most polluted sites, but not in foliose ones (Parmelia sulcata, Lobaria pulmonaria), whereas cortical CBSC did not change with distance from the road in any species. Strong positive correlations only occurred between the major medullary compound stictic acid present in L. pulmonaria and most heavy metals, consistent with a chelating role of stictic acid, but not of other studied CBSCs or in other species. However, heavy metal chelating did not protect L. pulmonaria against damage because this species experienced the strongest reduction in viability in the polluted sites. CBSCs with an accumulation potential for heavy metals should be quantified in lichen biomonitoring studies of heavy metals because they, like stictic acid, could overshadow pollutant inputs in some species rendering biomonitoring data less useful. In the two fruticose lichen species, CBSCs decreased with increasing heavy metal concentration, probably because heavy metal exposure impaired secondary metabolism. Thus, we found no support for a heavy metal protection role of any CBSCs in studied epiphytic lichens. No intraspecific relationships occurred between CBSCs versus N or C/N-ratio. Interspecifically, medullary CBSCs decreased and cortical CBSCs increased with increasing C/N-ratio. PMID:26437350

  19. An accurate benchmark description of the interactions between carbon dioxide and polyheterocyclic aromatic compounds containing nitrogen.

    Science.gov (United States)

    Li, Sicheng; Smith, Daniel G A; Patkowski, Konrad

    2015-07-01

    We assessed the performance of a large variety of modern density functional theory approaches for the adsorption of carbon dioxide on molecular models of pyridinic N-doped graphene. Specifically, we selected eight polyheterocyclic aromatic compounds ranging from pyridine and pyrazine to 1,6-diazacoronene and investigated their complexes with CO2 for a large range of intermolecular distances and including both in-plane and stacked orientations. The benchmark interaction energies were computed at the complete-basis-set limit MP2 level plus a CCSD(T) coupled-cluster correction in a moderate but carefully selected basis set. Using a set of 96 benchmark CCSD(T)-level interaction energies as a reference, we investigated the accuracy of DFT-based approaches as a function of the density functional, the dispersion correction, the basis set, and the counterpoise correction or lack thereof. While virtually all DFT variants exhibit some deterioration of accuracy for distances slightly shorter than the van der Waals minima, we were able to identify several schemes such as B2PLYP-D3 and M05-2X-D3 whose average errors on the entire benchmark data set are in the 5-10% range. The top DFT performers were subsequently used to investigate the energy profile for a carbon dioxide transition through model N-doped graphene pores. All investigated methods confirmed that the largest, N4H4 pore allows for a barrierless CO2 transition to the other side of a graphene sheet. PMID:26055458

  20. Predicting trace organic compound breakthrough in granular activated carbon using fluorescence and UV absorbance as surrogates.

    Science.gov (United States)

    Anumol, Tarun; Sgroi, Massimiliano; Park, Minkyu; Roccaro, Paolo; Snyder, Shane A

    2015-06-01

    This study investigated the applicability of bulk organic parameters like dissolved organic carbon (DOC), UV absorbance at 254 nm (UV254), and total fluorescence (TF) to act as surrogates in predicting trace organic compound (TOrC) removal by granular activated carbon in water reuse applications. Using rapid small-scale column testing, empirical linear correlations for thirteen TOrCs were determined with DOC, UV254, and TF in four wastewater effluents. Linear correlations (R(2) > 0.7) were obtained for eight TOrCs in each water quality in the UV254 model, while ten TOrCs had R(2) > 0.7 in the TF model. Conversely, DOC was shown to be a poor surrogate for TOrC breakthrough prediction. When the data from all four water qualities was combined, good linear correlations were still obtained with TF having higher R(2) than UV254 especially for TOrCs with log Dow>1. Excellent linear relationship (R(2) > 0.9) between log Dow and the removal of TOrC at 0% surrogate removal (y-intercept) were obtained for the five neutral TOrCs tested in this study. Positively charged TOrCs had enhanced removals due to electrostatic interactions with negatively charged GAC that caused them to deviate from removals that would be expected with their log Dow. Application of the empirical linear correlation models to full-scale samples provided good results for six of seven TOrCs (except meprobamate) tested when comparing predicted TOrC removal by UV254 and TF with actual removals for GAC in all the five samples tested. Surrogate predictions using UV254 and TF provide valuable tools for rapid or on-line monitoring of GAC performance and can result in cost savings by extended GAC run times as compared to using DOC breakthrough to trigger regeneration or replacement. PMID:25792436

  1. Redox-active tetrathiafulvalene and dithiolene compounds derived from allylic 1,4-diol rearrangement products of disubstituted 1,3-dithiole derivatives

    OpenAIRE

    Filipe Vilela; Skabara, Peter J; Mason, Christopher R.; Thomas D. J. Westgate; Asun Luquin; Coles, Simon J.; Hursthouse, Michael B.

    2010-01-01

    We present a series of compounds by exploiting the unusual 1,4-aryl shift observed for electron-rich 1,3-dithiole-2-thione and tetrathiafulvalene (TTF) derivatives in the presence of perchloric acid. The mechanistic features of this rearrangement are discussed since this synthetic strategy provides an alternative route for the synthesis and functionalisation of sulfur rich compounds including redox active compounds of TTFs, and a Ni dithiolene.

  2. Radiobiological half-lives for carbon-14 and hydrogen-3 leucine in man

    International Nuclear Information System (INIS)

    In vivo estimates of protein metabolism in many are often made by oral or intravenous administration of leucine or its ∼-ketoacid, ∼-ketoisocaproate, labeled with 14C or 3H. Previous estimates of radiation dose from such tracers have been based on the measurement of 14CO2 in breath. Using measurements of the decay of 3H or 14C leucine from plasma proteins, longer biological half-lives for these compounds were obtained. The estimated total-body radiation absorbed dose is 0.97 mrad/uCi for [1-14C]KIC (or [1-14C]leucine) and 0.11 mrad/+Ci for ]4,5-3H]leucine (or [3H]KIC). Assuming administered doses of 100 μCi each, the total-body radiation absorbed dose is still well within the limits set by the FDA for Radioactive Drug Research Committees. 12 references, 3 figures, 3 tables

  3. Validation test for carbon-14 migration and accumulation in a Canadian shield lake

    International Nuclear Information System (INIS)

    This particular BIOMOVS II Technical Report is concerned with modelling the transfer of C-14 through the aquatic food chain following release to a Canadian shield lake. Model performance has been tested against field data supplied by Atomic Energy of Canada Limited. Carbon-14 was added in 1978 to the epilimnion of a small Canadian Shield lake to investigate primary production and carbon dynamics. Data from this experiment were used within BIOMOVS II to provide a validation test, which involved modelling the fate of the C-14 added to the lake. The nature of the spike and the subsequent monitoring allowed the investigation of both short-term processes relevant to evaluation of the impacts of accidental releases as well as longer-term processes relevant to routine release and to solid waste disposal. Four models participated in the scenario: 1) a simple mass balance model of a lake (AECL, Whiteshell Laboratories, Canada); 2) a relatively complex deterministic dynamic compartment model (QuantiSci Ltd.,UK); 3) a complex deterministic model (Studsvik Model A) and a more complex probabilistic model (Studsvik Model B; Studsvik Eco and Safety AB, Sweden). Endpoints were C-14 concentrations in water, sediment and whitefish over a thirteen year period. Each model produced reasonable predictions when compared to the observed data and when uncertainty is taken into consideration. About 0.2 to 0.4% of the initial C-14 inventory to the lakes remained in the water at the end of the study, because of internal recycling of C-14 from sediments. The simple AECL model did not account for this internal recycling of C-14 and, in this respect, its predictions were not as realistic as those of the QuantiSci and Studsvik models for concentrations in water. However, the AECL model predictions for the C-14 inventory remaining in lake sediment were closest to the observed values. Overall, Studsvik Model B was the most accurate in simulating C-14 concentrations in water and in whitefish, but

  4. Interactions of 14C-labeled multi-walled carbon nanotubes with soil minerals in water

    International Nuclear Information System (INIS)

    Carbon nanotubes are often modified to be stable in the aqueous phase by adding extensive hydrophilic surface functional groups. The stability of such CNTs in water with soil or sediment is one critical factor controlling their environmental fate. We conducted a series of experiments to quantitatively assess the association between water dispersed multi-walled carbon nanotubes (MWCNTs) and three soil minerals (kaolinite, smectite, or shale) in aqueous solution under different sodium concentrations. 14C-labeling was used in these experiments to unambiguously quantify MWCNTs. The results showed that increasing ionic strength strongly promoted the removal of MWCNTs from aqueous phase. The removal tendency is inversely correlated with the soil minerals’ surface potential and directly correlated with their hydrophobicity. This removal can be interpreted by the extended Derjaguin–Landau–Verwey–Overbeek (EDLVO) theory especially for kaolinite and smectite. Shale, which contains large and insoluble organic materials, sorbed MWCNTs the most strongly. - Graphical abstract: The stability of multi-walled carbon nanotubes in an aqueous system containing kaolinite, smectite or shale as model soil minerals is investigated using the 14C-labeling technique. Highlights: ► The interactions between MWCNTs and kaolinite, smectite, or shale were probed. ► Surface potential and hydrophobicity of the particles governs their interactions. ► EDLVO can be used to interpret the interactions. ► Insoluble organic materials in shale strongly sorb MWCNTs.

  5. Environmental levels of carbon-14 around a Swedish nuclear power plant measured with accelerator mass spectrometry

    Science.gov (United States)

    Stenström, K.; Erlandsson, B.; Hellborg, R.; Wiebert, A.; Skog, G.

    1996-06-01

    14C is one of the radionuclides which are produced by nuclear power plants. The main part of the 14C, which is released during normal operation, is produced through neutron induced reactions in the cooling water and is released as airborne effluents (such as CO 2 and hydrocarbons) through the ventilation system of the plant to the surrounding environment. Because of the biological importance of carbon and the long half-life of 14C, it is of interest to measure the releases and their incorporation into living material in the environment of the power plants. In this pilot study the accelerator mass spectrometry (AMS) facility at the University of Lund has been used to measure the 14C activity concentration in vegetation around a Swedish nuclear power plant. AMS is suitable mainly because of the accuracy obtained within a short measuring time, which makes it possible to analyze a sufficient number of samples for a thorough investigation. The results of this study demonstrate that the AMS method is suitable for investigations of the influence on the local environment of reactor-released 14C by analysis of living material. To test dispersion models, however, air sampling both of emission source and in the surrounding of the plant seems more suitable.

  6. Application of the dose limitation system to the control of carbon-14 releases from heavy-water-moderated reactors

    International Nuclear Information System (INIS)

    Heavy-water-moderated reactors produce substantially more carbon-14 than light-water reactors. Applying the principles of the systems of dose limitation, the paper presents the rationale used for establishing the release limit for effluents containing this nuclide and for the decisions made regarding the effluent treatment in the third nuclear power station in Argentina. Production of carbon-14 in PHWR and the release routes are analysed in the light of the different effluent treatment possibilities. An optimization assessment is presented, taking into account effluent treatment and waste management costs, and the collective effective dose commitment due to the releases. The contribution of present carbon-14 releases to future individual doses is also analysed in the light of an upper bound for the contribution, representing a fraction of the individual dose limits. The paper presents the resulting requirements for the effluent treatment regarding carbon-14 and the corresponding regulatory aspects used in Argentina. (author)

  7. Simulation of carbon cycling, including dissolved organic carbon transport, in forest soil locally enriched with 14C

    Energy Technology Data Exchange (ETDEWEB)

    Tipping, Ed [Lancaster Environment Center; Chamberlain, Paul M. [Lancaster Environment Center; Froberg, Mats J. [Sveriges Lantbruksuniversitet; Hanson, Paul J [ORNL; Jardine, Philip M [ORNL

    2012-01-01

    The DyDOC model was used to simulate organic matter decomposition and dissolved organic matter (DOM) transport in deciduous forest soils at the Oak Ridge Reservation (ORR) in Tennessee, USA. The model application relied on extensive data from the Enriched Background Isotope study (EBIS), which made use of a local atmospheric enrichment of radiocarbon to establish a large-scale manipulation experiment with different inputs of 14C from both above-ground and below-ground litter. The aim of the modelling was to test if the processes that constitute DyDOC can explain the available observations for C dynamics in the ORR. More specifically we used the model to investigate the origins of DOM, its dynamics within the soil profile, and how it contributes to the formation of stable carbon in the mineral soil. The model was first configured to account for water transport through the soil, then observed pools and fluxes of carbon and 14C data were used to fit the model parameters that describe the rates of the metabolic transformations. The soils were described by a thin O-horizon, a 15 cm thick A-horizon and a 45-cm thick B-horizon. Within the thin O-horizon, litter is either converted to CO2 or to a second organic matter pool, which is converted to CO2 at a different rate, both pools being able to produce DOM. The best model performance was obtained by assuming that adsorption of downwardly transported DOM in horizons A and B, followed by further conversion to stable forms, produces mineral-associated carbon pools, while root litter is the source of non-mineral associated carbon, with relatively short residence times. In the simulated steady-state, most carbon entering the O-horizon leaves quickly as CO2, but 17% (46 gC m-2 a-1) is lost as DOC in percolating water. The DOM comprises mainly hydrophobic material, 40% being derived from litter and 60% from older organic matter pools (residence time ~ 10 years). Most of the DOM is converted to CO2 in the mineral soil, over

  8. Anomalous hydrogen absorption on non-stoichiometric iron-carbon compound

    International Nuclear Information System (INIS)

    Research highlights: → CnanoHx with Fe showed the characteristic hydrogen storage properties. → Anomalous hydrogen absorption on non-stoichiometric Fe-C was clarified. → More than 10 mass% of hydrogen was absorbed in the Fe-C phase. - Abstract: On the synthesis of nano-structural hydrogenated graphite by ball-milling under H2 atmosphere, iron contamination was mingled from steel balls during ball-milling. It is clarified by spectroscopic measurements that the mingled iron formed a non-stoichiometric iron-carbon (Fe-C) compound. The Fe-C phase was transformed to a well-ordered phase with H2 desorption at 450 oC, suggesting that the hydrogen atoms were anomalously trapped at the Fe-C phase. With respect to hydrogen absorbing properties, the mingled iron enhanced the hydrogen capacity by about 50% compared with iron free hydrogenated graphite, where H/Fe was about 13 mass%. Therefore, if the hydrogen absorption site originated in the Fe-C phase could be synthesized independently, it should be recognized as a promising hydrogen storage system.

  9. Supercritical Carbon Dioxide Extraction of Bioactive Compounds from Ampelopsis grossedentata Stems: Process Optimization and Antioxidant Activity

    Directory of Open Access Journals (Sweden)

    Da Sun

    2011-10-01

    Full Text Available Supercritical carbon dioxide (SC-CO2 extraction of bioactive compounds including flavonoids and phenolics from Ampelopsis grossedentata stems was carried out. Extraction parameters such as pressure, temperature, dynamic time and modifier, were optimized using an orthogonal array design of L9 (34, and antioxidant activities of the extracts were evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH free radical scavenging assay and ferrous ion chelating (FIC assay. The best conditions obtained for SC-CO2 extraction of flavonoids was 250 bar, 40 °C, 50 min, and with a modifier of methanol/ethanol (1:3, v/v, and that for phenolics extraction was 250 bar, 40 °C, 50 min, and with a modifier of methanol/ethanol (1:1, v/v. Meantime, flavonoids and phenolics were found to be mainly responsible for the DPPH scavenging activity of the extracts, but not for the chelating activity on ferrous ion according to Pearson correlation analysis. Furthermore, several unreported flavonoids such as apigenin, vitexin, luteolin, etc., have been detected in the extracts from A. grossedentata stems.

  10. Electrochemical detection of phenolic estrogenic compounds at clay modified carbon paste electrode

    Science.gov (United States)

    Belkamssa, N.; Ouattara, L.; Kawachi, A.; Tsujimura, M.; Isoda, H.; Chtaini, A.; Ksibi, M.

    2015-04-01

    A simple and sensitive electroanalytical method was developed to determine the Endocrine Disrupting chemical 4-tert-octylphenol on clay modified carbon paste electrode (Clay/CPE). The electrochemical response of the proposed electrode was studied by means of cyclic and square wave voltammetry. It has found that the oxidation of 4-tert-octylphenol on the clay/CPE displayed a well-defined oxidation peak. Under these optimal conditions, a linear relation between concentrations of 4-tert-octylphenol current response was obtained over range of 7.26×10-6 to 3.87×10-7 with a detection and quantification limit of 9.2×10-7 M and 3.06×10-6 M, respectively. The correlation coefficient is 0.9963. The modified electrode showed suitable sensitivity, high stability and an accurate detection of 4-tert-octylphenol. The modified electrode also relevant suitable selectivity for various phenolic estrogenic compounds.

  11. 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)

  12. Measurements of the Water Vapour, Tritium and Carbon-14 Content of the Middle Stratosphere over Southern England

    OpenAIRE

    Brown, F; Goldsmith, P.; Green, H F; Holt, A.; Parham, A. G.

    2011-01-01

    Measurements of the water vapour, tritium and carbon-14 content of the stratosphere at heights of between 80,000 and 100,000 feet, made over England during the years 1956 to 1960, are described. The tritium and carbon-14 concentrations are greater than those expected from natural production due to the cosmic radiation. The bulk of these two isotopes, at present in the stratosphere, has been injected there during the course of thermonuclear explosions. Mass spectrometric analyses show that t...

  13. Determination of the carbon content of domestic farm produces to estimate offsite C-14 ingestion dose

    International Nuclear Information System (INIS)

    The carbon content of grains, leafy and root vegetables, and fruits which the Koreans usually eat were calculated to use in the estimation of offsite C-14 ingestion dose. With the data of food intake per day in the Report on 1998 national health and nutrition survey- dietary intake survey, 5 age-group integrate d intake of the 4 farm produce groups were extracted for food items and the amount. Intake percentage in each food group were taken as food weighing factor for the foods. Carbon content was calculated using protein, fat, and carbohydrate content of the foods, and multiplied by the corresponding food weighing factor to derive the content of the food groups. The calculated carbon content of grains, leafy and root vegetables, and fruits were 39.%, 4.2%, 8.0%, and 5.9% respectively. Grains and fruits were not much different from ODCM for carbon content, but vegetables were higher by 0.7%∼4.5%

  14. Building-Related Symptoms among Office Employees Associated with Indoor Carbon Dioxide and Total Volatile Organic Compounds

    Directory of Open Access Journals (Sweden)

    Chung-Yen Lu

    2015-05-01

    Full Text Available This study investigated whether sick building syndrome (SBS complaints among office workers were associated with the indoor air quality. With informed consent, 417 employees in 87 office rooms of eight high-rise buildings completed a self-reported questionnaire for symptoms experienced at work during the past month. Carbon dioxide (CO2, temperature, humidity and total volatile organic compounds (TVOCs in each office were simultaneously measured for eight office hours using portable monitors. Time-averaged workday difference between the indoor and the outdoor CO2 concentrations (dCO2 was calculated as a surrogate measure of ventilation efficiency for each office unit. The prevalence rates of SBS were 22.5% for eye syndrome, 15.3% for upper respiratory and 25.4% for non-specific syndromes. Tiredness (20.9%, difficulty in concentrating (14.6%, eye dryness (18.7% were also common complaints. The generalized estimating equations multivariate logistic regression analyses showed that adjusted odds ratios (aORs and 95% confidence interval (CI per 100 ppm increase in dCO2 were significantly associated with dry throat (1.10, 95% CI = (1.00–1.22, tiredness (1.16, 95% CI = (1.04–1.29 and dizziness (1.22, 95% CI = (1.08–1.37. The ORs for per 100 ppb increases in TVOCs were also associated with upper respiratory symptoms (1.06, 95% CI = (1.04–1.07, dry throat (1.06, 95% CI = (1.03–1.09 and irritability (1.02, 95% CI = (1.01–1.04. In conclusion, the association between some SBS symptoms and the exposure to CO2 and total VOCs are moderate but may be independently significant.

  15. Prise en compte du carbone 14 dans le modèle PASIM

    OpenAIRE

    Duclos, Etienne

    2010-01-01

    J'ai effectué mon stage de fin d'étude d'ingénieur ISIMA au sein de l'Institut National de la Recherche Agronomique (INRA), dans l'Unité de Recherche sur l'Ecosystème Prairial (UREP). Mon stage a été effectué en collaboration avec l'Institut de Radioprotection et de Sûreté Nucléaire (IRSN). J'ai été chargé d'ajouter la gestion du carbone 14 au sein de PaSim, modèle de simulation de prairie gérant déjà les flux de carbone et d'azote. Il m'a donc fallu faire la distinction, au...

  16. Carbon isotope (14C, 12C) measurements to quantify sources of atmospheric carbon monoxide in urban air

    International Nuclear Information System (INIS)

    Atmospheric air samples were collected during the Winter of 1989-90 in Albuquerque, NM USA, for carbon isotope (14C, 12C) analysis of carbon monoxide (CO). An experimental sample design was prepared to target periods when the concentration of CO exceeds the 9 μL/L (volume fraction), 8 hour National Ambient Air Quality Standard (NAAQS) and during periods of attainment. Sampling sites, time of day, sampling duration, and meteorology were carefully considered so that source impacts be optimal. A balanced sampling factorial design was used to yield maximum information from the constraints imposed; the number of samples was limited by the number of sample canisters available, time, and resources. Carbon isotope measurements of urban air, ''clean-air'' background from Niwot Ridge, Colorado, average (wood) logs and oxygenated-gasolines were used in a 3-source model to calculate the contribution of woodburning to the total atmospheric CO burden in Albuquerque. Results show that the estimated fractional contribution of residential wood combustion (Θ' RWC) ranged from 0 to 0.30 of CO concentrations corrected for ''clean-air'' background. For these same samples, the respective CO concentrations attributed to woodburning range from 0 to 0.90 μmol/mol (mole fraction), well below the NAAQS. In all cases, fossil CO is the predominant source of ambient CO concentrations ranging from 0.96 to 6.34 μmol/mol. A final comment is made on the potential of fossil CO measurements as an indirect tracer of atmospheric benzene, relevant to exposure risk estimates of motor vehicle emissions and occupational health and safety standards. (author). 26 refs, 3 figs, 4 tabs

  17. Tritium- and carbon-14-contents of wines of different vintage from the northern and southern hemisphere

    International Nuclear Information System (INIS)

    The carbon-14 and tritium radioactivity contents of up to 19 vintages of German and Southafrican wines were compared. A similar large dependence of the 14C- and of the 3H-activity in the German wine on the nuclear weapon tests of the years 1962/63 was found out. The radioactivity level is also 1977/78 still essentially higher than before 1950. The Southafrican wines have been influenced considerably less by nuclear explosions. The highest 3H-values were found in the vintage 1963 of the German wine with 5910 pCi/litre and in the vintage 1964 of the Southafrican wine with 510 pCi/litre. (orig.)

  18. Controlling the number of walls in multi walled carbon nanotubes/alumina hybrid compound via ball milling of precipitate catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Nosbi, Norlin [School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia (USM), 14300 Nibong Tebal, Seberang Perai Selatan, Pulau Pinang (Malaysia); Akil, Hazizan Md, E-mail: hazizan@usm.my [School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia (USM), 14300 Nibong Tebal, Seberang Perai Selatan, Pulau Pinang (Malaysia); Cluster for Polymer Composite (CPC), Science and Engineering Research Centre, Engineering Campus, Universiti Sains Malaysia (USM), 14300 Nibong Tebal, Seberang Perai Selatan, Pulau Pinang (Malaysia)

    2015-06-15

    Graphical abstract: - Highlights: • We report that, to manipulate carbon nanotubes geometry and number of walls are by controlling the precipitate catalyst size. • Number of walls and geometry effects depend on the milling time of the precipitate catalyst. • Increasing milling of time will decrease the carbon nanotubes number of walls. • Increasing milling of time will increase the carbon nanotubes thermal conductivity. - Abstract: This paper reports the influence of milling time on the structure and properties of the precipitate catalyst of multi walled carbon nanotubes (MWCNT)/alumina hybrid compound, produced through the chemical vapour deposition (CVD) process. For this purpose, light green precipitate consisted of aluminium, nickel(II) nitrate hexahydrate and sodium hydroxide mixture was placed in a planetary mill equipped with alumina vials using alumina balls at 300 rpm rotation speed for various milling time (5–15 h) prior to calcinations and CVD process. The compound was characterized using various techniques. Based on high-resolution transmission electron microscopy analysis, increasing the milling time up to 15 h decreased the diameter of MWCNT from 32.3 to 13.1 nm. It was noticed that the milling time had a significant effect on MWCNT wall thickness, whereby increasing the milling time from 0 to 15 h reduced the number of walls from 29 to 12. It was also interesting to note that the carbon content increased from 23.29 wt.% to 36.37 wt.% with increasing milling time.

  19. Controlling the number of walls in multi walled carbon nanotubes/alumina hybrid compound via ball milling of precipitate catalyst

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • We report that, to manipulate carbon nanotubes geometry and number of walls are by controlling the precipitate catalyst size. • Number of walls and geometry effects depend on the milling time of the precipitate catalyst. • Increasing milling of time will decrease the carbon nanotubes number of walls. • Increasing milling of time will increase the carbon nanotubes thermal conductivity. - Abstract: This paper reports the influence of milling time on the structure and properties of the precipitate catalyst of multi walled carbon nanotubes (MWCNT)/alumina hybrid compound, produced through the chemical vapour deposition (CVD) process. For this purpose, light green precipitate consisted of aluminium, nickel(II) nitrate hexahydrate and sodium hydroxide mixture was placed in a planetary mill equipped with alumina vials using alumina balls at 300 rpm rotation speed for various milling time (5–15 h) prior to calcinations and CVD process. The compound was characterized using various techniques. Based on high-resolution transmission electron microscopy analysis, increasing the milling time up to 15 h decreased the diameter of MWCNT from 32.3 to 13.1 nm. It was noticed that the milling time had a significant effect on MWCNT wall thickness, whereby increasing the milling time from 0 to 15 h reduced the number of walls from 29 to 12. It was also interesting to note that the carbon content increased from 23.29 wt.% to 36.37 wt.% with increasing milling time

  20. Reinforcing of thermoplastic polycarbonate and polysulfone with carbon fibers: Production and characteristics of UD-compound objects

    Science.gov (United States)

    Fitzer, E.; Jaeger, H.

    1988-01-01

    The production and characteristics of the carbon fiber reinforced thermoplastics polycarbonate and polysulfone are described. The production of prepregs from defined polymer solutions is emphasized along with methods of optimizing the production of compounds. The characteristics of unidirectionally reinforced thermoplastics, such as shear strength, bending strength, and impact resistance are compared with regard to fracture behavior, the influence of intermediate layers, and the behavior under cryogenic conditions and under slightly elevated temperatures. The problem of adhesion between high strength carbon fibers and thermoplastics is examined, taking into account the effect of moisture on the shear strength and the impact resistance.

  1. Carbon sources in the Beaufort Sea revealed by molecular lipid biomarkers and compound specific isotope analysis

    Directory of Open Access Journals (Sweden)

    I. Tolosa

    2012-10-01

    Full Text Available Molecular lipid biomarkers (hydrocarbons, alcohols, sterols and fatty acids and compound specific isotope analysis of suspended particulate organic matter (SPM and surface sediments of the Mackenzie Shelf and slope (Southeast Beaufort Sea, Arctic Ocean, were studied in summer 2009. The concentrations of the molecular lipid markers, characteristic of known organic matter sources, were grouped and used as proxies to evaluate the relative importance of fresh algal, detrital algal, fossil, C3 terrestrial plants, bacterial and zooplankton material in the sedimentary organic matter (OM.

    Fossil and detrital algal contributions were the major fractions of the freshwater SPM from the Mackenzie River with ~34% each of the total molecular biomarkers. Fresh algal, C3 terrestrial, bacterial and zooplanktonic components represented much lower percentages, 17, 10, 4 and < 1%, respectively. In marine SPM from the Mackenzie slope, the major contributions were fresh and detrital algal components (> 80% with a minor contribution of fossil and C3 terrestrial biomarkers. Characterization of the sediments revealed a major sink of refractory algal material mixed with some fresh algal material, fossil hydrocarbons and a small input of C3 terrestrial sources. In particular, the sediments from the shelf and at the mouth of the Amundsen Gulf presented the highest contribution of detrital algal material (60–75% whereas those from the slope contained the highest proportion of fossil (40% and C3 terrestrial plant material (10%. Overall, considering that the detrital algal material is marine derived, autochthonous sources contributed more than allochthonous sources to the OM lipid pool. Using the ratio of an allochthonous biomarker (normalized to total organic carbon, TOC found in the sediments to those measured at the river mouth water, we estimated that the fraction of terrestrial material preserved in the

  2. Analysis and Characterization of Organic Carbon in Early Holocene Wetland Paleosols using Ramped Pyrolysis 14C and Biomarkers

    Science.gov (United States)

    Vetter, L.; Schreiner, K. M.; Fernandez, A.; Rosenheim, B. E.; Tornqvist, T. E.

    2014-12-01

    Radiocarbon analyses are a key tool for quantifying the dynamics of carbon cycling and storage in both modern soils and Quaternary paleosols. Frequently, bulk 14C dates of paleosol organic carbon provide ages older than the time of soil burial, and 14C dates of geochemical fractions such as alkali and acid extracts (operationally defined as humic acids) can provide anomalously old ages when compared to coeval plant macrofossil dates. Ramped pyrolysis radiocarbon analysis of sedimentary organic material has been employed as a tool for investigating 14C age spectra in sediments with multiple organic carbon sources. Here we combine ramped pyrolysis 14C analysis and biomarker analysis (lignin-phenols and other cupric oxide products) to provide information on the source and diagenetic state of the paleosol organic carbon. We apply these techniques to immature early Holocene brackish wetland entisols from three sediment cores in southeastern Louisiana, along with overlying basal peats. Surprisingly, we find narrow 14C age spectra across all thermal aliquots from both paleosols and peats. The weighted bulk 14C ages from paleosols and overlying peats are within analytical error, and are comparable to independently analyzed 14C AMS dates from charcoal fragments and other plant macrofossils from each peat bed. Our results suggest high turnover rates of carbon in soils relative to input of exogenous carbon sources. These data raise broader questions about processes within the active soil and during pedogenesis and burial of paleosols that can effectively homogenize radiocarbon content in soils across the thermochemical spectrum. The concurrence of paleosol and peat 14C ages also suggests that, in the absence of peats with identifiable plant macrofossils, ramped pyrolysis 14C analyses of paleosols may be used to provide ages for sea-level indicators.

  3. Measurement and analysis of Carbon-14 released from pressurized water reactor in Korea

    International Nuclear Information System (INIS)

    Since the amount of Carbon-14 released from pressurized water reactor (PWR) is small and its concentration is low, it is not used as a main monitored nuclide for environmental release in PWR in general. However, the dose conversion coefficient of C-14 in CO2 is relatively high, there is a possibility to overestimate public exposure dose with the assumption that all amount of C-14 is resulted from CO2. Therefore, a monitoring plan should be established to manage the effluent from PWR in safe. This plan consists of (1) specifying the chemical form of C-14 (2) evaluating its effect on environment. The majority of the C-14 released from PWR is in a gaseous form in CO2 and CH4. In order to monitor C-14 in PWR, Korea Hydro and Nuclear Power (KHNP) devised C-14 sampling instrument which can collect CO2 and methane separately. It is composed of three main components, that is, primary CO2 sampler, a methane oxidisation assembly and a secondary CO2 sampler. The primary CO2 sampler has one water bubbler and two NaOH bubblers. The water bubbler prevents the accumulation of NaOH at other bubblers, 2M-NaOH bubblers collect all CO2 in the gas to produce sodium carbonate (Na2CO3). Then the methane oxidisation assembly convert methane and CO to CO2. The catalyst is composed of equal mixture of Alumina with Palladium coating (1.0%) and Platinum coating (0.5%). The temperature of a furnace is maintained 500 .deg. C approximately, to convert CO and methane into CO2. Retaining time of the gas in catalytic is designed to be about 25 seconds to maximize conversion. After the catalytic conversion, the gas is cooled and is passed through the NaOH solution bubblers. The concentration of CO2 and methane at main vent lines in Yonggwang Unit-3 was analyzed using Gas Chromatography in order to evaluate the optimal treatment condition for the sample and estimate the optimal operating time for this device. As a result, the concentration of CO2 was approximately 450 ppm in average and that of

  4. Synthesis and reactivity of compounds containing ruthenium-carbon, -nitrogen, and -oxygen bonds

    Energy Technology Data Exchange (ETDEWEB)

    Hartwig, J.F.

    1990-12-01

    The products and mechanisms of the thermal reactions of several complexes of the general structure (PMe{sub 3}){sub 4}Ru(X)(Y) and (DMPM){sub 2}Ru(X)(Y) where X and Y are hydride, aryl, and benzyl groups, have been investigated. The mechanism of decomposition depends critically on the structure of the complex and the medium in which the thermolysis is carried out. The alkyl hydride complexes are do not react with alkane solvent, but undergo C-H activation processes with aromatic solvents by several different mechanisms. Thermolysis of (PMe{sub 3}){sub 4}Ru(Ph)(Me) or (PMe{sub 3}){sub 4}Ru(Ph){sub 2} leads to the ruthenium benzyne complex (PMe{sub 3}){sub 4}Ru({eta}{sup 2}-C{sub 6}H{sub 4}) (1) by a mechanism which involves reversible dissociation of phosphine. In many ways its chemistry is analogous to that of early rather than late organo transition metal complexes. The synthesis, structure, variable temperature NMR spectroscopy and reactivity of ruthenium complexes containing aryloxide or arylamide ligands are reported. These complexes undergo cleavage of a P-C bond in coordinated trimethylphosphine, insertion of CO and CO{sub 2} and hydrogenolysis. Mechanistic studies on these reactions are described. The generation of a series of reactive ruthenium complexes of the general formula (PMe{sub 3}){sub 4}Ru(R)(enolate) is reported. Most of these enolates have been shown to bind to the ruthenium center through the oxygen atom. Two of the enolate complexes 8 and 9 exist in equilibrium between the O- and C-bound forms. The reactions of these compounds are reported, including reactions to form oxygen-containing metallacycles. The structure and reactivity of these ruthenium metallacycles is reported, including their thermal chemistry and reactivity toward protic acids, electrophiles, carbon monoxide, hydrogen and trimethylsilane. 243 refs., 10 tabs.

  5. Tracing carbon flow through coral reef food webs using a compound-specific stable isotope approach

    KAUST Repository

    McMahon, Kelton

    2015-11-21

    Coral reefs support spectacularly productive and diverse communities in tropical and sub-tropical waters throughout the world’s oceans. Debate continues, however, on the degree to which reef biomass is supported by new water column production, benthic primary production, and recycled detrital carbon (C). We coupled compound-specific stable C isotope ratio (δ13C) analyses with Bayesian mixing models to quantify C flow from primary producers to coral reef fishes across multiple feeding guilds and trophic positions in the Red Sea. Analyses of reef fishes with putative diets composed primarily of zooplankton (Amblyglyphidodon indicus), benthic macroalgae (Stegastes nigricans), reef-associated detritus (Ctenochaetus striatus), and coral tissue (Chaetodon trifascialis) confirmed that δ13C values of essential amino acids from all baseline C sources were both isotopically diagnostic and accurately recorded in consumer tissues. While all four source end-members contributed to the production of coral reef fishes in our study, a single-source end-member often dominated dietary C assimilation of a given species, even for highly mobile, generalist top predators. Microbially reworked detritus was an important secondary C source for most species. Seascape configuration played an important role in structuring resource utilization patterns. For instance, Lutjanus ehrenbergii showed a significant shift from a benthic macroalgal food web on shelf reefs (71 ± 13 % of dietary C) to a phytoplankton-based food web (72 ± 11 %) on oceanic reefs. Our work provides insights into the roles that diverse C sources play in the structure and function of coral reef ecosystems and illustrates a powerful fingerprinting method to develop and test nutritional frameworks for understanding resource utilization.

  6. Synthesis and reactivity of compounds containing ruthenium-carbon, -nitrogen, and -oxygen bonds

    International Nuclear Information System (INIS)

    The products and mechanisms of the thermal reactions of several complexes of the general structure (PMe3)4Ru(X)(Y) and (DMPM)2Ru(X)(Y) where X and Y are hydride, aryl, and benzyl groups, have been investigated. The mechanism of decomposition depends critically on the structure of the complex and the medium in which the thermolysis is carried out. The alkyl hydride complexes are do not react with alkane solvent, but undergo C-H activation processes with aromatic solvents by several different mechanisms. Thermolysis of (PMe3)4Ru(Ph)(Me) or (PMe3)4Ru(Ph)2 leads to the ruthenium benzyne complex (PMe3)4Ru(η2-C6H4) (1) by a mechanism which involves reversible dissociation of phosphine. In many ways its chemistry is analogous to that of early rather than late organo transition metal complexes. The synthesis, structure, variable temperature NMR spectroscopy and reactivity of ruthenium complexes containing aryloxide or arylamide ligands are reported. These complexes undergo cleavage of a P-C bond in coordinated trimethylphosphine, insertion of CO and CO2 and hydrogenolysis. Mechanistic studies on these reactions are described. The generation of a series of reactive ruthenium complexes of the general formula (PMe3)4Ru(R)(enolate) is reported. Most of these enolates have been shown to bind to the ruthenium center through the oxygen atom. Two of the enolate complexes 8 and 9 exist in equilibrium between the O- and C-bound forms. The reactions of these compounds are reported, including reactions to form oxygen-containing metallacycles. The structure and reactivity of these ruthenium metallacycles is reported, including their thermal chemistry and reactivity toward protic acids, electrophiles, carbon monoxide, hydrogen and trimethylsilane. 243 refs., 10 tabs

  7. Carbonated Eclogite Solidus Between 14 and 20 GPa: Results from the Model CMAS-CO2 System and Contrasting Solidus Behavior to Carbonated Peridotite

    Science.gov (United States)

    Keshav, S.; Gudfinnsson, G. H.

    2007-12-01

    The carbonate ledge at ~2.0 GPa is a pronounced feature of the carbonated peridotite solidus. At the ledge, where the CO2-bearing phase changes from vapour to carbonate, the melt composition becomes carbonatitic. After this drop, the solidus of carbonated peridotite gradually rises in P-T space, up to at least 12 GPa. Between 14 and 16 GPa, Keshav et al. (2007) reported another drop in the solidus of carbonated peridotite in the model CMS-CO2 system. Similar to the lower-pressure topology, the solidus at higher pressure resumes a positive slope between 16-20 GPa, and seems to flatten between 22 and 26 GPa. Concomitant with this second drop, the melts become extremely calcic (Ca/Ca+Mg, Ca no.-0.62) at 16 and 20 GPa, but attain more magnesio-carbonatitic (Ca no.-0.40) character both at shallower or greater depths than the transition zone. Clearly, the second drop in the carbonated peridotite solidus has tremendous consequences for geological processes in the deep mantle. The other major rock-type presumed to be present in the mantle is eclogite of broadly basaltic composition. Clarifying the solidus topology of carbonated eclogite in model systems over a similar pressure range is also an important task, because the solidus topology affects the fate of subducted carbonate in the deeper mantle. The position of the solidus of carbonated eclogite will address its impact on local or extensive melting (if it occurs), the possible relationship between the carbonated peridotite and carbonated eclogite solidi at these depths (400-600 km), their respective incipient melts, and ultimately the possibility of carbonate survival at these and greater depths. With these issues in mind, we have determined the solidus of model carbonated eclogite in model CMAS- CO2 system between 14 and 20 GPa. At 14 and 16 GPa, the melts are in equilibrium with cpx, majoritic garnet, stishovite, and magnesite. At 20 GPa, the melts are in equilibrium with calcium-perovskite (capv), garnet, stishovite

  8. Mountain scale modeling of transient, coupled gas flow, heat transfer and carbon-14 migration

    International Nuclear Information System (INIS)

    We simulate mountain-scale coupled heat transfer and gas flow at Yucca Mountain. A coupled rock-gas flow and heat transfer model, TGIF2, is used to simulate mountain-scale two-dimensional transient heat transfer and gas flow. The model is first verified against an analytical solution for the problem of an infinite horizontal layer of fluid heated from below. Our numerical results match very well with the analytical solution. Then, we obtain transient temperature and gas flow distributions inside the mountain. These distributions are used by a transient semianalytical particle tracker to obtain carbon-14 travel times for particles starting at different locations within the repository. Assuming that the repository is filled with 30-year-old waste at an initial areal power density of 57 kw/acre, we find that repository temperatures remain above 60 degrees C for more than 10,000 years. Carbon-14 travel times to the surface are mostly less than 1000 years, for particles starting at any time within the first 10,000 years

  9. A study of melt-compounded nanocomposites of polycarbonate and carbon nanotubes in the melt and solid states

    OpenAIRE

    Choong, Gabriel Y. H.

    2014-01-01

    Polycarbonate-carbon nanotube nanocomposites are promising materials for electrostatic shielding and conductive packaging applications. The nanotubes impart electrical conductivity and increases thermal conductivity and stiffness of the matrix. However, the nanofiller also affects the rheology, and hence the evolution of a filler network during processing. This thesis examines the effects of matrix molar mass and of compounding temperature on the thermal, rheological, electrical and mechanica...

  10. Tracing carbon fixation in phytoplankton—compound specific and total 13C incorporation rates

    OpenAIRE

    Grosse, J; van Breugel, P; Boschker, H.T.S.

    2015-01-01

    Measurement of total primary production using 13C incorporation is a widely established tool. However, these bulk measurements lack information about the fate of fixed carbon: the production of major cellular compounds (carbohydrates, amino acids, fatty acids, and DNA/RNA) is affected by for instance nutrient availability as their C:N:P requirements differ. Here, we describe an approach to combine established methods in gas chromatography/isotope ratio mass spectrometry (GC/C-IRMS) and recent...

  11. Preparing poly(aryl ethers) using alkaline earth metal carbonates, organic acid salts, and optionally copper compounds, as catalysts

    International Nuclear Information System (INIS)

    This patent describes an improved process for preparing poly(aryl ethers) and poly(aryl ether ketones) by the reaction of a mixture of at least one bisphenol and at least one dihalobenzenoid compound, and/or a halophenol. The improvement comprises providing to the reaction, a base which is a combination of an alkaline earth metal carbonate and/or bicarbonate and a potassium, rubidium, or cesium salt of an organic acid or combination of organic salts thereof

  12. Preparing poly(aryl ethers) using alkaline earth metal carbonates, organic acid salts, and optionally copper compounds, as catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Winslow, P.A.; Kelsey, D.R.; Matzner, M.

    1988-09-27

    This patent describes an improved process for preparing poly(aryl ethers) and poly(aryl ether ketones) by the reaction of a mixture of at least one bisphenol and at least one dihalobenzenoid compound, and/or a halophenol. The improvement comprises providing to the reaction, a base which is a combination of an alkaline earth metal carbonate and/or bicarbonate and a potassium, rubidium, or cesium salt of an organic acid or combination of organic salts thereof.

  13. Effect of aromatics on the adsorption of thiophenic sulfur compounds from model diesel fuel by activated carbon cloth

    OpenAIRE

    NAVIRI FALLAH, Rahimeh; Azizian, Saeid; REGGERS, Guy; Carleer, Robert; Schreurs, Sonja; Ahenach, Janat; Meynen, Vera; Yperman, Jan

    2014-01-01

    The effects of aromatic compound presence in real diesel fuel on the adsorption of sulfur species onto activated carbon cloth (ACC) were investigated. Equilibrium and kinetics adsorption of benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (DMDBT) in the presence of naphthalene (NP) and 1-methylnaphthalene (1-MNP) from prepared model diesel fuels onto ACC and its oxidized forms were studied. The total sulfur concentration inmodel diesel fuelwas 300 ppmw. The initial...

  14. Adsorptive removal of hydrophobic organic compounds by carbonaceous adsorbents: A comparative study of waste-polymer-based,coal-based activated carbon, and carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    Fei Lian; Chun Chang; Yang Du; Lingyan Zhu; Baoshan Xing; Chang Liu

    2012-01-01

    Adsorption of the hydrophobic organic compounds (HOCs) trichloroethylene (TCE),1,3-dichlorobenzene (DCB),1,3-dinitrobenzene (DNB) and γ-hexachlorocyclohexane (HCH) on five different carbonaceous materials was compared.The adsorbents included three polymer-based activated carbons,one coal-based activated carbon (F400) and multiwalled carbon nanotubes (MWNT).The polymerbased activated carbons were prepared using KOH activation from waste polymers:polyvinyl chloride (PVC),polyethyleneterephthalate (PET) and tire rubber (TR).Compared with F400 and MWNT,activated carbons derived from PVC and PET exhibited fast adsorption kinetics and high adsorption capacity toward the HOCs,attributed to their extremely large hydrophobic surface area (2700 m2/g) and highly mesoporous structures.Adsorption of small-sized TCE was stronger on the tire-rubber-based carbon and F400 resulting from the pore-filling effect.In contrast,due to the molecular sieving effect,their adsorption on HCH was lower.MWNT exhibited the lowest adsorption capacity toward HOCs because of its low surface area and characteristic of aggregating in aqueous solution.

  15. Application of mesoporous carbon as a solid-phase microextraction fiber coating for the extraction of volatile aromatic compounds.

    Science.gov (United States)

    Zhang, Xi; Zang, Xiaohuan; Zhang, Guijiang; Wang, Chun; Wang, Zhi

    2015-08-01

    A mesoporous carbon was fabricated using MCM-41 as a template and sucrose as a carbon source. The carbon material was coated on stainless-steel wires by using the sol-gel technique. The prepared solid-phase microextraction fiber was used for the extraction of five volatile aromatic compounds (chlorobenzene, ethylbenzene, o-xylene, bromobenzene, and 4-chlorotoluene) from tea beverage samples (red tea and green tea) prior to gas chromatography with mass spectrometric detection. The main experimental parameters affecting the extraction of the volatile aromatic compounds by the fiber, including the extraction time, sample volume, extraction temperature, salt addition, and desorption conditions, were investigated. The linearity was observed in the range from 0.1 to 10.0 μg/L with the correlation coefficients (r) ranging from 0.9923 to 0.9982 and the limits of detection were less than 10.0 ng/L. The recoveries of the volatile aromatic compounds by the method from tea beverage samples at spiking levels of 1.0 and 10.0 μg/L ranged from 73.1 to 99.1%. PMID:26041569

  16. Enhanced catalysis of the electrochemical hydrogen evolution reaction using composites of molybdenum-based compounds, gold nanoparticles and carbon.

    Science.gov (United States)

    Joshi, Ubisha; Lee, Jing; Giordano, Cristina; Malkhandi, Souradip; Yeo, Boon Siang

    2016-08-21

    Molybdenum nitride has been recently reported to interact synergistically with gold to show an enhanced activity for the electrochemical hydrogen evolution reaction (2H(+) + 2e(-)→ H2, HER). In this work, we elucidated the roles of nitrogen, carbon, molybdenum and gold on this observed phenomenon. Composites of Mo-based compounds, carbon black (black pearl 2000) and/or Au nanoparticles (AuNP) were prepared, and their activities for the HER in a 0.5 M H2SO4 electrolyte were measured using linear sweep voltammetry. We show and discuss here for the first time that, while the presence of carbon is necessary for the synergy phenomenon, the nitrogen atoms present in the compounds play no apparent role in this synergy. In fact, all the compounds containing Mo, namely Mo2N, MoB and metallic Mo(0), exhibited extensive synergy with Au for the HER. A hypothesis for the enhanced catalysis of H2 evolution by the mixed metal composites is proposed and discussed. PMID:27424516

  17. Reconciling Change in Oi-Horizon Carbon-14 with Mass Loss for an Oak Forest

    Energy Technology Data Exchange (ETDEWEB)

    Hanson, Paul J [ORNL; Swanston, Christopher W. [Lawrence Livermore National Laboratory (LLNL); Garten Jr, Charles T [ORNL; Todd Jr, Donald E [ORNL; Trumbore, Susan E. [University of California, Irvine

    2005-01-01

    First-year litter decomposition was estimated for an upland-oak forest ecosystem using enrichment or dilution of the 14C-signature of the Oi-horizon. These isotopically-based mass-loss estimates were contrasted with measured mass-loss rates from past litterbag studies. Mass-loss derived from changes in the 14C-signature of the Oi-horizon suggested mean mass loss over 9 months of 45% which was higher than the corresponding 9-month rate extrapolated from litterbag studies (~35%). Greater mass loss was expected from the isotopic approach because litterbags are known to limit mass loss processes driven by soil macrofauna (e.g., fragmentation and comminution). Although the 14C-isotope approach offers the advantage of being a non-invasive method, it exhibited high variability that undermined its utility as an alternative to routine litterbag mass loss methods. However, the 14C approach measures the residence time of C in the leaf litter, rather than the time it takes for leaves to disappear; hence radiocarbon measures reflect C immobilization and recycling in the microbial pool, and do not necessarily replicate results from litterbag mass loss. The commonly applied two-compartment isotopic mixing model was appropriate for estimating decomposition from isotopic enrichment of near-background soils, but it produced divergent results for isotopic dilution of a multi-layered system with litter cohorts having independent 14C-signatures. This discrepancy suggests that cohort-based models are needed to adequately capture the complex processes involved in carbon transport associated with litter mass-loss. Such models will be crucial for predicting intra- and interannual differences in organic horizon decomposition driven by scenarios of climatic change.

  18. Secondary brown carbon - Formation of light-absorbing compounds in atmospheric particulates from selected dicarbonyls and amines

    Science.gov (United States)

    Kampf, Christopher; Filippi, Alexander; Hoffmann, Thorsten

    2015-04-01

    One of the main open questions regarding organic compounds in atmospheric chemistry today is related to the formation of optically-active compounds and the occurrence of so called brown carbon (Andreae and Gelencsér, 2006). While organic compounds in ambient fine particles for decades have been assumed to not absorb solar radiation, thus resulting in a net cooling effect on climate (IPCC, 2007), it is now generally accepted that a continuum of light-absorbing carbonaceous species is present in fine aerosols (Pöschl, 2003). In this study, light-absorbing compounds from reactions between dicarbonyl compounds, i.e., glyoxal, methylglyoxal, acetylacetone, 2,3-butanedione, 2,5-hexanedione, and glutaraldehyde, and amine species, i.e., ammonia and glycine, were investigated at atmospherically relevant concentrations in bulk solution experiments mimicking atmospheric particulates. Product analyses were performed using UV/Vis spectrophotometry and (ultra) high performance liquid chromatography coupled to diode array detection and ion trap mass spectrometry (HPLC-DAD-ESI-MS/MS), as well as ultra-high resolution (Orbitrap) mass spectrometry (UHPLC-ESI-HRMS/MS). We demonstrate that light-absorbing compounds are formed from a variety of atmospherically relevant dicarbonyls via particle phase reactions with amine nucleophiles. Single dicarbonyl and mixed dicarbonyl experiments were performed and products were analyzed. The reaction products are suggested to be cyclic nitrogen containing compounds such as imidazoles or dihydropyridines as well as open chain compounds resulting from aldol condensation reactions. Further, the reactive turnover was found to be higher at increasing pH values. The aforementioned processes may be of higher relevance in regions with high aerosol pH, e.g., resulting from high ammonia emissions as for example in northern India (Clarisse et al., 2009). References Andreae, M.O., and Gelencsér, A. (2006): Black carbon or brown carbon? The nature of light

  19. Detection of carbon-fluorine bonds in organofluorine compounds by Raman spectroscopy using a copper-vapor laser

    Science.gov (United States)

    Sharts, Clay M.; Gorelik, Vladimir S.; Agoltsov, A. M.; Zlobina, Ludmila I.; Sharts, Olga N.

    1999-02-01

    The Raman spectra of fluoro-organic compounds show specific emission bands for carbon-fluorine bonds in the range 500- 800 wave numbers (cm-1)). With very limited exceptions, biological materials do not contain carbon- fluorine bonds. Fluoro-organic compounds introduced into biological samples can be detected by a Raman emission signal. Normal mode C-F bond bands are observed: (1) at 710- 785 cm -1 for trifluoromethyl groups; (2) at 530-610 cm -1 for aromatic organofluorine bonds; (3) a range centered at 690 cm -1 for difluoromethylene groups. Specific examples of normal mode C-F bond emissions for organofluorine compounds containing trifluoromethyl groups are: 1-bromoperfluorooctane, 726 cm -1; perfluorodecanoic acid, 730 cm -1; triperfluoropropylamine, 750 cm -1; 1,3,5-tris- (trifluoromethyl)-benzene, 730 cm -1; Fluoxetine (Prozac) commercial powdered pill at 782 cm -1. Compounds containing aromatic C-F bonds are: hexafluorobenzene, 569 cm MIN1; pentafluoropyridine, 589 cm -1. Difluoromethylene groups: perfluorodecalin, 692 cm-1; perfluorocyclohexane, 691 cm -1. Raman spectra were observed with a standard single monochromator. The 510.8 nm light source was a copper-vapor laser operated at 3-10 watts with 10-12 nanosecond pulses at 10 kHz repetition rate. Detection was made with a time-gated photomultiplier tube. Resonance Raman spectra were also observed at 255.4 nm, using a frequency doubling crystal. Observed spectra were free of fluorescence with very sharp strong C-F lines.

  20. Assessment of adequacy of pancreatic enzyme replacement with the multiple-phase carbon-14-triolein test

    International Nuclear Information System (INIS)

    The carbon-14-triolein absorption test was used to investigate fat absorption and its response to pancreatic enzyme replacement therapy in 10 men with pancreatic steatorrhoea. Absorption was increased in all, from 1,14 plus minus 1,2% of the dose per hour (group mean plus minus SD) to 2,85 plus minus 2,33% (P less than 0,01) by the simultaneous administration of 8 tablets of enteric-coated pancreatic enzymes (Nutrizym; Merck). In patients with normal or high gastric acid secretion, neutralization of gastric acid with 30 ml magnesium trisilicate had no effect on absorption while the addition of an extract of gastric secretions (Enzynorm; Noristan) to the therapy of the 1 achlorhydric patient improved absorption from 2,2% to 3,81%. The 14C fat test offers a rapid and more acceptable alternative method for determining individual response to pancreatic enzyme replacement therapy than the conventional 72-hour faecal fat excretion measurement. The enteric-coated pancreatin preparation used in this study appears to be optimally effective under conditions of normal gastric acid secretion

  1. Dietary carbon sources of mussels and tubeworms from Galapagos hydrothermal vents determined from tissue 14C activity

    International Nuclear Information System (INIS)

    The results of an investigation of the dietary carbon sources of mussels and tubeworms from Galapagos hydrothermal vents, using data from 14C and 13C/12C ratio measurements in tissues, are reported. It is shown that: (1) filter-feeding organisms in the vent system are directly or indirectly incorporating 'dead' carbon of magmatic origin into their tissues; (2) approximately 25% or less of the dietary carbon available to the mussels is from sedimenting particulate organic carbon fixed photosynthetically at the surface; and (3) mussel tissue is incorporating relatively more 'dead' dissolved inorganic carbon than is mussel shell carbonate in specimens collected at the same location near the vent. (U.K.)

  2. Effects of carbon black distribution on the electrical properties of Br/Epdm compounds

    International Nuclear Information System (INIS)

    The correlations between mechanical and electrical properties of butadiene/ethylene propylene diene terpolymer (BR/EPDM) and the distribution of carbon black levels are studied. It was found that the BR phase in the blends, compared to the EPDM phase, is more preferential for the used type of carbon black, probably because the lower viscosity and lower polarity of the BR phase. Tensile strength increases with an increase of carbon black. Possible reasons for these results are discussed

  3. Analysis of Redox Series of Unsymmetrical 1,4-Diamido-9,10-anthraquinone-Bridged Diruthenium Compounds.

    Science.gov (United States)

    Mandal, Abhishek; Hoque, Md Asmaul; Grupp, Anita; Paretzki, Alexa; Kaim, Wolfgang; Lahiri, Goutam Kumar

    2016-03-01

    The unsymmetrical diruthenium complexes [(bpy)2Ru(II)(μ-H2L(2-))Ru(III)(acac)2]ClO4 ([3]ClO4), [(pap)2RuII(μ-H2L(2-))Ru(III)(acac)2]ClO4 ([4]ClO4), and [(bpy)2Ru(II)(μ-H2L(2-))Ru(II)(pap)2](ClO4)2 ([5](ClO4)2) have been obtained by way of the mononuclear precursors [(bpy)2Ru(II)(H3L(-))]ClO4 ([1]ClO4) and [(pap)2Ru(II)(H3L(-))]ClO4 ([2]ClO4) (where bpy = 2,2′-bipyridine, pap = 2-phenylazopyridine, acac(-) = 2,4-pentanedionate, and H4L = 1,4-diamino-9,10-anthraquinone). Structural characterization by single-crystal X-ray diffraction and magnetic resonance (nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR)) were used to establish the oxidation state situation in each of the isolated materials. Cyclic voltammetry, EPR, and ultraviolet-visible-near-infrared (UV-vis-NIR) spectroelectrochemistry were used to analyze the multielectron transfer series of the potentially class I mixed-valent dinuclear compounds, considering the redox activities of differently coordinated metals, of the noninnocent bridge and of the terminal ligands. Comparison with symmetrical analogues [L2′Ru(μ-H2L)RuL2′](n) (where L′ = bpy, pap, or acac(-)) shows that the redox processes in the unsymmetrical dinuclear compounds are not averaged, with respect to the corresponding symmetrical systems, because of intramolecular charge rearrangements involving the metals, the noninnocent bridge, and the ancillary ligands. PMID:26887785

  4. Treatment of sludge containing nitro-aromatic compounds in reed-bed mesocosms – Water, BOD, carbon and nutrient removal

    International Nuclear Information System (INIS)

    Highlights: ► It is necessary to improve existing and develop new sludge management techniques. ► One method is dewatering and biodegradation of compounds in constructed wetlands. ► The result showed high reduction of all tested parameters after treatment. ► Plants improve degradation and Phragmites australis is tolerant to xenobiotics. ► The amount of sludge could be reduced by 50–70%. - Abstract: Since the mid-1970s, Sweden has been depositing 1 million ton d.w sludge/year, produced at waste water treatment plants. Due to recent legislation this practice is no longer a viable method of waste management. It is necessary to improve existing and develop new sludge management techniques and one promising alternative is the dewatering and treatment of sludge in constructed wetlands. The aim of this study was to follow reduction of organic carbon, BOD and nutrients in an industrial sludge containing nitro-aromatic compounds passing through constructed small-scale wetlands, and to investigate any toxic effect such as growth inhibition of the common reed Phragmites australis. The result showed high reduction of all tested parameters in all the outgoing water samples, which shows that constructed wetlands are suitable for carbon and nutrient removal. The results also showed that P. australis is tolerant to xenobiotics and did not appear to be affected by the toxic compounds in the sludge. The sludge residual on the top of the beds contained low levels of organic carbon and is considered non-organic and could therefore be landfilled. Using this type of secondary treatment method, the amount of sludge could be reduced by 50–70%, mainly by dewatering and biodegradation of organic compounds.

  5. Adsorption of organic compounds onto activated carbons from recycled vegetables biomass.

    Science.gov (United States)

    Mameli, Anna; Cincotti, Alberto; Lai, Nicola; Crisafulli, Carmelo; Sciré, Salvatore; Cao, Giacomo

    2004-01-01

    The removal of organic species from aqueous solution by activated carbons is investigated. The latter ones are prepared from olive husks and almond shells. A wide range of surface area values are obtained varying temperature and duration of both carbonization and activation steps. The adsorption isotherm of phenol, catechol and 2,6-dichlorophenol involving the activated carbons prepared are obtained at 25 degrees C. The corresponding behavior is quantitatively correlated using classical isotherm, whose parameters are estimated by fitting the equilibrium data. A two component isotherm (phenol/2,6-dichlorophenol) is determined in order to test activated carbon behavior during competitive adsorption. PMID:15347202

  6. 10 CFR 30.21 - Radioactive drug: Capsules containing carbon-14 urea for “in vivo” diagnostic use for humans.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Radioactive drug: Capsules containing carbon-14 urea for...: Capsules containing carbon-14 urea for “in vivo” diagnostic use for humans. (a) Except as provided in...-14 urea (allowing for nominal variation that may occur during the manufacturing process) each,...

  7. 14CO2-assimilation, translocation of 14C, and 14C-carbonate uptake in different organs of spring barley plants in relation to adult-plant resistance to powdery mildew

    International Nuclear Information System (INIS)

    The cultivar Peruvian of spring barley, which is susceptible at all growth stages, and Asse, which exhibits adult-plant resistance to powdery mildew, were compared in 14CO2 assimilation, distribution of 14C, and 14C-carbonate uptake in different organs of healthy and infected plants. The reduction of 14CO2 assimilation in infected plants at the first and fourth leaf stages was greater in Peruvian than in Asse. In Peruvian, the 14C which was fixed by the infected third leaf of plants with mildew on the lower 3 leaves remained in the third leaves with very little translocation to other parts of the plant. Infection of the lower three leaves at the fourth leaf stage reduced 14CO2 assimilation in noninfected fourth leaves of Asse less than that of Peruvian, but the flow of 14C from the healthy fourth leaves into other plant parts such as leaf sheaths was markedly stimulated in Peruvian compared to Asse. Infection also reduced the uptake of 14C-carbonate by seedling roots, the reduction being greater in Peruvian than Asse. A greater proportion of the 14C absorbed by roots of Asse was translocated to the infected leaves than that of Peruvian. It was concluded that powdery mildew disrupted the normal pattern of photosynthesis and translocation of metabolites in a susceptible cultivar more markedly than in an adult-plant-resistant cultivar of spring barley. (author)

  8. Labeling of carbon pools in Bradyrhizobium japonicum and Rhizobium leguminosarum bv viciae bacteroids following incubation of intact nodules with 14CO2

    International Nuclear Information System (INIS)

    The aim of the work reported here was to ascertain that the patterns of labeling seen in isolated bacteroids also occurred in bacteroids in intact nodules and to observe early metabolic events following exposure of intact nodules to 14CO2. Intact nodules of soybean (Glycine max L. Merr. cv Ripley) inoculated with Bradyrhizobium japonicum USDA 110 and pea (Pisum sativum L. cv Progress 9) inoculated with Rhizobium leguminosarum by viciae isolate 128C53 were detached and immediately fed 14CO2 for 1 to 6 min. Bacteroids were purified from these nodules in 5 to 7 min after the feeding period. In the cytosol from both soybean and pea nodules, malate had the highest radioactivity, followed by citrate and aspartate. In peas, asparagine labeling equaled that of aspartate. In B. japonicum bacteroids, malate was the most rapidly labeled compound, and the rate of glutamate labeling was 67% of the rate of malate labeling. Aspartate and alanine were the next most rapidly labeled compounds. R. leguminosarum bacteroids had very low amounts of 14C and, after a 1-min feeding, malate contained 90% of the radioactivity in the organic acid fraction. Only a trace of activity was found in aspartate, whereas the rate of glutamate and alanine labeling approached that of malate after 6 min of feeding. Under the conditions studied, malate was the major form of labeled carbon supplied to both types of bacteroids. These results with intact nodules confirm our earlier results with isolated bacteroids, which showed that a significant proportion of provided labeled substrate, such as malate, is diverted to glutamate. This supports the conclusion that microaerobic conditions in nodules influence carbon metabolism in bacteroids. (author)

  9. Production and characterization of activated carbons from waste candeia (eremanthus erythropappus) and their application on organic compounds adsorption

    International Nuclear Information System (INIS)

    In this work, two activated carbons were prepared, using as activating agents ZnCl2 and K2CO3, denominated CA/ZnCl2,CA/ K2CO3, respectively, from waste generated in the process of extraction of essential oil of Candeia, a tree native of Brazil. These carbons were characterized by scanning electron microscopy, thermal analysis, elemental analysis, BET surface area and iodine index. These materials were tested in the adsorption of model molecules: Phenol and Methylene Blue, and a commercial activated carbon (Merck) was used for comparison purposes. Adsorption isotherms for CA/ZnCl2,CA/K2CO3 and CA/Com showed maximum sorption capacities of 297, 228 and 271 mg g-1 for Methylene Blue and 109,195 and 161 mg g-1 for phenol respectively. The results showed that the carbons are efficient in the adsorption process of molecules tested. The isotherms were fitted to equations of Langmuir and Freundlich. The Langmuir model provided better fit, showing that the adsorbents have energetically uniform surfaces. The materials produced were characterized as potential adsorbents for organic compounds that can be used as an alternative for obtaining activated carbons adding value to the residue.

  10. Monodisperse carbon nanopearls in a foam-like arrangement: a new carbon nano-compound for cold cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Levesque, A.; Binh, Vu Thien; Semet, V.; Guillot, D.; Fillit, R.Y.; Brookes, M.D.; Nguyen, T.P

    2004-10-01

    This paper reports the low cost, high yield chemical vapor deposition synthesis of a potentially novel carbon nanomaterial using nickel nanocluster-catalysed dissociation of acetylene at 700 deg. C. The resulting 'carbon nanopearls' are 150 nm in diameter with {approx}85% monodispersity, with a solid structure composed of both amorphous and nanocrystalline ({approx}2 nm repeat unit) regions. The nanopearls form 3D space-filling 'strings' which give rise to a macroscopic foam-like appearance. The nanopearls have been characterized using scanning electron microscopy, high resolution transmission electron microscopy, X-ray microdiffraction, Raman spectroscopy and energy dispersive X-rays. A mechanism for the formation of the nanopearls is proposed based on concentric layers of {approx}4x4 nm graphitic flakes. The small radius of curvature of each nanopearl and the corrugation at the atomic scale of the surface resulting from the unclosed graphitic flakes result in excellent field emission properties. It has been demonstrated that a film of conditioned carbon nanopearls exhibits Fowler-Nordheim field emission behavior, with currents of up to 50 {mu}A readily obtainable under continuous emission in moderate vacuum. It is proposed that such emitters would provide significantly higher yield, uniform emission characteristics than non-oriented films of carbon nanotubes due to the reproducibly high density of nanopearl emitter sites.

  11. Optimizing sample pretreatment for compound-specific stable carbon isotopic analysis of amino sugars in marine sediment

    Science.gov (United States)

    Zhu, R.; Lin, Y.-S.; Lipp, J. S.; Meador, T. B.; Hinrichs, K.-U.

    2014-09-01

    Amino sugars are quantitatively significant constituents of soil and marine sediment, but their sources and turnover in environmental samples remain poorly understood. The stable carbon isotopic composition of amino sugars can provide information on the lifestyles of their source organisms and can be monitored during incubations with labeled substrates to estimate the turnover rates of microbial populations. However, until now, such investigation has been carried out only with soil samples, partly because of the much lower abundance of amino sugars in marine environments. We therefore optimized a procedure for compound-specific isotopic analysis of amino sugars in marine sediment, employing gas chromatography-isotope ratio mass spectrometry. The whole procedure consisted of hydrolysis, neutralization, enrichment, and derivatization of amino sugars. Except for the derivatization step, the protocol introduced negligible isotopic fractionation, and the minimum requirement of amino sugar for isotopic analysis was 20 ng, i.e., equivalent to ~8 ng of amino sugar carbon. Compound-specific stable carbon isotopic analysis of amino sugars obtained from marine sediment extracts indicated that glucosamine and galactosamine were mainly derived from organic detritus, whereas muramic acid showed isotopic imprints from indigenous bacterial activities. The δ13C analysis of amino sugars provides a valuable addition to the biomarker-based characterization of microbial metabolism in the deep marine biosphere, which so far has been lipid oriented and biased towards the detection of archaeal signals.

  12. Carbon-14, tritium, stable isotope and chemical measurements on thermal waters from the Tauranga region

    International Nuclear Information System (INIS)

    The chemical compositions of groundwater from the Tauranga region are affected to varying degrees by reducing conditions due to buried organic matter. The levels of some dissolved constituents are also affected by mixing with sea water contained within the rocks and by rock-water interaction. Dissolved gas compositions range from oxygen-bearing to methane-bearing reflecting the varying redox conditions. Excess air may be present but further experiments are necessary to confirm this. Apparent ages deduced from carbon-14 measurements (corrected using 12C dilution and 13C fractionation methods) range from 2-25,000 years, suggesting that some of the waters were recharged during late Pleistocene or early Holocene time. ΔD and Δ18 O values of the oldest waters are slightly more negative than those of younger samples; this may indicate recharge during a cooler climate, in agreement with the 14C ages. Very low but significantly non-zero tritium contents (TR=(0.007-0.059)+-0.007) were measured using the high tritium-enrichment facilities at INS and the very low-background counters at the University of Bern. The tritium is thought to derive from contamination or nuclear reactions in the aquifer rocks rather than from recharge water

  13. Synthesis of 14C-labelled hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), 2,4,6-trinitrotoluene (TNT), nitrocellulose (NC) and glycidyl azide polymer (GAP) for use in assessing the biodegradation potential of these energetic compounds

    International Nuclear Information System (INIS)

    Within the framework of an R and D project on bioremediation of soils contaminated with energetic compounds, the biodegradation of energetic products such as hexogen (RDX), trinitrotoluene (TNT), nitrocellulose (NC) and glycidyl azide polymer (GAP) is under study. Microcosm assays must be performed with radioactive carbon-14 labelled products in order to follow the biodegradation process. 14C-RDX was prepared by nitration of hexamethylenetetramine (HMTA) according to the Hale process. 14C-ring and methyl labelled TNTs synthesized according to the Dorey and Carper procedure. 14C-cellulose was synthesized from 14C-glucose by Acetobacter xylinum. Nitration of the 14C-cellulose yielded 14C-nitrocellulose. 14C-glycidyl azide polymer was obtained by polymerization and azidation of 14C-epichlorohydrin (ECH) which was synthesized from 14C-glycerol. Hydrochlorination of 14C-glycerol and epoxidation of the resulting 14C-1,3-dichloro 2-propanol yielded 14C-ECH. The syntheses of these 14C-labelled explosives are described in this paper. (Author)

  14. In vivo uptake of carbon-14-colchicine for identification of tumor multidrug resistance

    Energy Technology Data Exchange (ETDEWEB)

    Mehta, B.M.; Rosa, E.; Biedler, J.L. [Nuclear Medicine Research Lab., New York, NY (United States)] [and others

    1994-07-01

    A major limitation in the treatment of cancer with natural product chemotherapeutic agents is the development of multidrug resistance (MDR). Multidrug resistance is attributed to enhanced expression of the multidrug resistance gene MDR1. Colchicine (CHC) is known to be one of the MDR drugs. The authors have previously demonstrated that it is possible to distinguish multidrug resistant tumors from the multidrug-sensitive tumors in vivo on the basis of tritium ({sup 3}H) uptake following injection of {sup 3}H-CHC. The present studies were carried out in xenografted animals using {sup 14}C-CHC which may be more indicative of {sup 11}C-labeled CHC distribution with regard to circulating metabolites, since metabolic processes following injection of (ring C, methoxy-{sup 11}C)-CHC may produce significant amounts of circulating 1l-carbon fragments (i.e., methanol and/or formaldehyde). Experiments were carried out at a dose of 2 mg/kg. Activity concentration per injected dose was approximately twice as great in sensitive as in resistant tumors (p < 0.05) at 60 min following intravenous injection of {sup 14}C-CHC. About 75% of total activity was CHC in the sensitive tumors. The findings are further confirmed by the quantitative autoradiographic evaluation of resistant and sensitive tumors. These studies confirm our previous observations that it is possible to noninvasively distinguish multidrug-resistant tumors from sensitive tumors in vivo based on uptake of an injected MDR drug using a{sup 14}C-labeled CHC at the same position and of comparable specific activity to a {sup 11}C-CHC tracer used for PET imaging. 16 refs., 5 figs., 2 tabs.

  15. Compound Hertzian Chain Model for Copper-Carbon Nanocomposites' Absorption Spectrum

    CERN Document Server

    Kokabi, Alireza; Saeedi, Saman; Moftakharzadeh, Ali; Vesaghi, Mohammad Ali; Fardmanesh, Mehdi

    2011-01-01

    The infrared range optical absorption mechanism of Carbon-Copper composite thin layer coated on the Diamond-Like Carbon (DLC) buffer layer has been investigated. By consideration of weak interactions between copper nanoparticles in their network, optical absorption is modeled using their coherent dipole behavior induced by the electromagnetic radiation. The copper nanoparticles in the bulk of carbon are assumed as a chain of plasmonic dipoles, which have coupling resonance. Considering nearest neighbor interactions for this metallic nanoparticles, surface plasmon resonance frequency ({\\omega}\

  16. Wax ester-like compounds as biosurfactants produced by Dietzia maris from n-alkane as a sole carbon source.

    Science.gov (United States)

    Nakano, Miyo; Kihara, Masaki; Iehata, Shunpei; Tanaka, Reiji; Maeda, Hiroto; Yoshikawa, Takeshi

    2011-10-01

    The hydrocarbon-degrading bacterium Dietzia maris WR-3 was isolated from a consortium comprising ammonia-oxidizing and denitrifying bacteria derived from marine sediments. Here, we examined biosurfactant production by strain WR-3 when cultured using several different carbon (D-glucose, n -decane, n -hexadecane, motor oil, olive oil, and rapeseed oil) and nitrogen (NH(4) )(2) SO(4) , NaNO(3) , yeast extract, and polypeptone) sources as growth substrates. Strain WR-3 was able to grow and reduce the surface tension of culture broth to 31±1.0 mN m(-1) when cultured using n -hexadecane and nitrate ions. The surface-active compounds produced by strain WR-3 were extracted and analyzed by thin layer chromatography. Moreover, the main components in the extract were further purified and subjected to gas chromatography/mass spectrometry (GC/MS). From the analysis, the surface-active compounds were tentatively identified as wax ester-like compounds, which were synthesized from the degradation process of n -alkane. The production of surface-active compounds by strain WR-3 promoted attachment of cells to hydrocarbon droplets via increased cell hydrophobicity, thus allowing enhanced degradation of water immiscible substrates. As Dietzia spp. can grow and produce wax esters from the degradation process of hydrocarbons, these marine bacteria are potentially useful for the bioremediation of hydrocarbon-contaminated environments. PMID:21656811

  17. Product and corporate carbon footprint using the compound method based on financial accounts. The case of Osorio wind farms

    International Nuclear Information System (INIS)

    Highlights: • We applied novel organisation-product-based-life-cycle assessment to Osorio Wind Farms. • This study includes sources, phases and areas previously unreported for the wind power sector. • MC3 assess carbon footprint in a practical and comprehensive manner. • MC3 is suitable for its application in major international projects. - Abstract: The challenge of developing clean and renewable energy sources is becoming ever more urgent. Over the last decade, the concept of carbon footprint has been used to report direct and indirect greenhouse gas emissions and as a support for sustainable consumption decisions. However, the discrepancies in the approaches based on either the product or corporate carbon footprint can seriously hinder its successful implementation. The so-called compound method based on financial accounts is a tiered hybrid method which enables the calculation of both the product and corporate carbon footprint. This work aims to assess this method as a tool for carbon footprint through its implementation in a comprehensive life-cycle assessment of the Osorio Wind Farms in Brazil. The total cumulative life-cycle emissions are 362.455 t CO2eq, representing 18.33 gr CO2eq per kW h delivered to the Brazilian national power grid. The difference with regard to previous works derives from its broader scope and different assumptions. In this study the comparable value from wind turbine manufacture, transport and construction is 8.42 gr CO2eq per kW h, 56% lower than the mean figure reported by Arvesen and Hertwich (2012). This study includes sources, phases and areas previously unreported in the carbon footprint reviews for the wind power sector. We conclude that the compound method based on financial accounts is a practical method that allows the definition of a more comprehensive goal and scope. Its implementation at Osorio Wind Farms demonstrates the method’s suitability for application in major international projects and institutions

  18. Control of atmospheric emissions of volatile organic compounds using impregnated active carbons

    Energy Technology Data Exchange (ETDEWEB)

    Alvim Ferraz, M.C.M.; Moeser, S.; Tonhaeeuser, M. [Oporto University, Oporto (Portugal). Chemical Engineering Dept.

    1999-10-01

    The combination of carbon adsorption with catalytic complete oxidation for control of emissions of n-hexane, 2,3-dimethylbutane, cyclohexane and benzene is analysed. The activities of activated carbons prepared with almond shells and impregnated with CoO, Co{sub 3}O{sub 4} and CrO{sub 3} were compared, in relation with carbon structure, catalyst content and catalyst species. The microcatalytic-chromatographic technique developed was very suitable for rapid comparison of catalytic activities, that are higher for carbons with a better development of surface area and pore volumes, and increased with increasing catalyst content. Catalytic activity of cobalt is better than that of chromium, the oxidation state of cobalt in Co{sub 3}O{sub 4} being better than in CoO. The catalytic activity depends clearly on the hydrocarbons chemical structure. 20 refs., 4 figs., 3 tabs.

  19. Mass spectrometric analysis of stable carbon isotopes in abiogenic and biogenic natural compounds

    International Nuclear Information System (INIS)

    This report describes the general methodology of sup/13/ carbon analysis on mass spectrometer and various preparation systems developed for conversion of samples into isotopically non-fractionated and purified carbon dioxide. Laboratory standards required for sup/13/ C analysis have been calibrated against international standards. The reproducibility/accuracy of sample preparation and analysis on mass spectrometer for sup/13/ C or sup/12/ C measurement is well within the internationally acceptable limits. (author)

  20. Applicability of Activated Carbon to Treatment of Waste Containing Iodine-Labeled Compounds

    International Nuclear Information System (INIS)

    The applicability of activated carbon prepared from sawdust (SD) by one-step chemical activation process using H3PO4 (H) to treatment of aqueous waste contaminated with iodine-labeled prolactin (I-PRL) has been investigated. Treatment processes were performed under the varying conditions; contact time, temperature, carbon type, carbon dosage, and different particle size of activated carbon (SDH). Effect of aqueous waste volume has been investigated to calculate the batch factor (V/M) and the distribution coefficient (Kd). The used activated carbon (SDH) was characterized by N2 adsorption, FTIR, density, ph, point of zero charge phpzc, moisture and ash content. Methylene blue (MB) and iodine number was calculated by adsorption from solution. In order to investigate the mechanism of sorption and potential rate controlling steps, pseudo first- and second-order equations, intra particle diffusion equation and the Elovich equation have been used to test experimental data. Kinetic analysis of the four models has been carried out for system variables in order to assess which model provides the best fit predicted data with experimental results. 7 M NaOH can be used for regeneration of spent SDH activated carbon with the efficiency of 99.6% and the regenerated carbon can be reused for five cycles effectively. The prospect of applying the SDH activated carbon prepared from agricultural by-product, sawdust, to treatment of aqueous waste contaminated with I-PRL appears promising and is considered highly applicable because of its high adsorption capacity, available at low cost, easily regenerated and reused

  1. Carbon-13 magnetic relaxation rates or iron (III) complexes of some biogenic amines and parent compounds in aqueous solutions

    International Nuclear Information System (INIS)

    Spin-lattice relaxation rates (R1) from naturally occuring C-13 F.T. N.M.R. spectra of some catecholamines and parent compounds with Iron(III) at pD = 4 were determined in order to elucidate the molecular mechanism underlying their association in aqueous solutions. Complexation was observed only for catecholic ligands. The R1 values were used to calculate iron-carbon scaled distances, and two complexation models were proposed where the catecholic function binds Fe(III) in the first and second coordination spheres respectively. The latter case was shown to be the consistent with the molecular geometries. (orig.)

  2. Improvement in Superconducting Properties of MgB2 Superconductors by Nanoscale Carbon-Based Compound Doping

    Institute of Scientific and Technical Information of China (English)

    Si-Hai Zhou

    2008-01-01

    MgB2 is a relatively new superconductor; it has attracted great interest from superconductor researchers all over the world. Thorough investigations have been carried out to study the material fabrication, as well as to study the material and superconducting properties from a fundamental physics point of view. The University of Wollongong has played a very active role in this research and a leading role in the research on high critical current density and high critical magnetic fields. Our recent research on the improve- ment of critical current density and the upper critical magnetic field by carbon-based compound doping is reviewed in this paper.

  3. Compound-specific carbon isotopic fractionation during transport of phthalate esters in sandy aquifer.

    Science.gov (United States)

    Liu, Hui; Li, YanXi; He, Xi; Sissou, Zakari; Tong, Lei; Yarnes, Chris; Huang, Xianyu

    2016-02-01

    The present paper aims to evaluate the carbon isotopic fractionation of phthalate esters (PAEs) during transport in an sandy aquifer. Breakthrough curves of di-methyl phthalate (DMP), di-ethyl phthalate (DEP), and di-n-butyl phthalate (DBP) in mixed solution were determined by miscible displacement experiment, and simulated using HYDRUS-1D software. The stable carbon isotopes (δ(13)C) of 3 PAEs in effluent were analyzed at different times. Results showed that, in the transport process in sandy sediment, PAEs are mainly trapped into the pore space instead of being adsorbed on the surface of particles. At the initial stage of transport, PAEs with lighter carbon tend to run faster in the sandy sediment, and PAEs with heavier carbon run after. However, there is no priority for the transport of PAEs with different carbon isotopes at Stage Ⅱ with mainly time-limited sorption. So the transport-based isotope fractionation occurs in the front area of contaminant plume. This effect may be relevant for interpreting carbon isotope signatures in the real contaminant site. PMID:26539707

  4. A General Method for the Rapid Determination of Carbon-14- and Hydrogen-3-Labelled Substances by Gas Chromatography

    International Nuclear Information System (INIS)

    A method is described for the determination of 14C- and 3H- labelled substances by gas chromatography using different size flow counters. The method of cracking substances in a current of hydrogen gas is especially suitable for 3H-labelled compounds because it is free from the disadvantages encountered when the substances are first oxidized and the water formed subsequently converted. The general applicability of this method is shown for different classes of compounds. The analysis is independent of the chemical composition of the compound. By using a part oi the apparatus very rapid analyses of vaporizable 14C- and apparently all 3H-labelled substances can be made by direct injection into the reaction chamber. The apparatus can also be used for the oxidation procedure. (author)

  5. The strength of the R-T exchange coupling in R2Fe14B compounds; an approach based on high-field magnetization measurements

    International Nuclear Information System (INIS)

    By performing high-field magnetization measurements on Gd2Fe14-xMnxB and Tb2Fe14-xMnxB powdered samples that are oriented in the sample holder by the applied field it is possible to improve the accuracy of earlier reported values for the R-T exchange-coupling constant of these R2Fe14B compounds. In addition, the two-sublattice model that has been applied previously has been extended to a three-sublattice model with two magnetic rare-earth sublattices for the Er and Tm compounds in an attempt to describe the experimentally observed low-field susceptibility. It turns out however, that mainly the iron-manganese sublattice is responsible for this susceptibility

  6. Diffusion-type model of the global carbon cycle for the estimation of dose to the world population from releases of carbon-14 to the atmosphere

    International Nuclear Information System (INIS)

    A nonlinear dynamic model of the exchange of carbon among the atmosphere, terrestrial biosphere, and ocean is described and applied to estimating the radiation dose to the world's population from the release of 14C to the atmosphere from the nuclear power industry. A computer implementation of the model, written in the IBM Continuous System Modeling Program III (CSMP III) simulation language, is presented. The model treats the ocean as a diffusive medium with respect to vertical transport of carbon, and the nonlinear variation of CO2 partial pressure with the total inorganic carbon concentration in surface waters is taken into account in calculating the transfer rate from ocean to atmosphere. Transfers between the atmosphere and terrestrial biosphere are represented by nonlinear equations which consider CO2 fertilization and impose a constraint on the ultimate total carbon mass in the biosphere

  7. Carbon-14 dating of a mummy from 'Caverna da Babilonia', Rio Novo Country, south of Minas Gerais (MG, Brazil)

    International Nuclear Information System (INIS)

    The vegetable fibers of a cloth wrapping a mummy of a woman, found in 'Caverna da Babilonia' (MG, Brazil), were dated with carbon-14. There is strong evidence that it is a pre-colombian mummym since the age of the sample is 600 + - 80 years (1σ). (C.L.B.)

  8. A semi-micro combustion assembly for the determination of carbon and hydrogen in actinide compounds

    International Nuclear Information System (INIS)

    A rapid combustion unit (Baird and Tatlock) incorporating a combustion chamber provided with baffle plates for complete combustion of the sample without the use of a catalyst has been assembled in a glove box for the determination of carbon and hydrogen in actinide complexes. The unit has been modified employing a movable electric furnace and a proportional temperature controller, for decomposition of the sample at desired heating rates. The set-up was standardised employing various reference materials such as benzoic acid, acetanilide, sulphanilamide and 1-chloro 2:4 dinitrobenzene and the standard deviation in the measurements evaluated. It has also been used successfully for the determination of carbon in uranium carbide and carbon and hydrogen in some uranyl-β-diketone-amine N-oxide complexes and in plutonium(IV) oxalate. (auth.)

  9. Release of (14)C-labelled carbon nanotubes from polycarbonate composites.

    Science.gov (United States)

    Rhiem, Stefan; Barthel, Anne-Kathrin; Meyer-Plath, Asmus; Hennig, Michael P; Wachtendorf, Volker; Sturm, Heinz; Schäffer, Andreas; Maes, Hanna M

    2016-08-01

    Waste disposal of carbon nanotube (CNT) containing products is expected to be the most important pathway for release of CNTs into the environment. In the present work, the use of radiolabelled CNTs ((14)C-CNT) for polycarbonate polymer nanocomposites with 1 wt% (14)C-CNT content allowed for the first time to quantify and differentiate the CNT release according to the type of impact along the materials' ageing history. After an initial exposure of the nanocomposite by solar-like irradiation, further environmental impacts were applied to composite material. They aimed at mimicking disposal site conditions that may induce further ageing effects and CNT release. This study included shaking in water, rapid temperature changes, soaking in humic acid solution as well as waste water effluent, and, finally, gentle mechanical abrasion. All ageing impacts were applied sequentially, both on pristine (control) and on solar-irradiated nanocomposites. All experiments were accompanied by absolute quantification of radioactive release as well as chemical and morphological analyses of the nanocomposite surfaces using infra-red (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The morphological analysis showed that spectral irradiation can uncover CNT networks on the outer nanocomposite surface layers by polymer degradation. After having subjected the solar-irradiated nanocomposite to all studied disposal site effect, the total radioactive release was quantified to amount to 64 mg CNT/m(2), whereas only 0.8 mg CNT/m(2) were found for the un-irradiated control sample. Solar degradation of polymers was thus found to significantly increase the propensity of the studied polymer nanocomposites to release CNTs during ageing effects at the product's end-of-life typical for disposal sites. PMID:27194367

  10. Terpenylic acid and nine-carbon multifunctional compounds formed during the aging of β-pinene ozonolysis secondary organic aerosol

    Science.gov (United States)

    Sato, Kei; Jia, Tianyu; Tanabe, Kiyoshi; Morino, Yu; Kajii, Yoshizumi; Imamura, Takashi

    2016-04-01

    Recent field and laboratory studies suggest that forest aerosol particles contain more highly functionalized organic molecules than pinonic acid, a traditional molecular maker of secondary organic aerosol (SOA) particles. To investigate the reaction mechanisms during the aging of biogenic SOAs, the gases and particles formed from the ozonolysis of β- and α-pinene were exposed to OH radicals in a laboratory chamber. The particle samples were collected before and after OH exposure for analysis by liquid chromatography-negative electrospray ionization time-of-flight mass spectrometry. Pinic acid and terpenylic acid were abundant products in both β- and α-pinene ozonolysis SOA particles. Terpenylic acid and products with m/z 201.08 present in β-pinene SOA particles increased upon exposing SOA to OH radicals, whereas 3-methyl-1,2,3-butanetricarboxylic acid present in α-pinene SOA particles increased upon exposing SOA to OH radicals. The products with m/z 201.08 were suggested to be C9H14O5 compounds. Similar C9H14O5 compounds and terpenylic acid were also detected in SOA particles formed from the photooxidation of nopinone, a major first-generation product of β-pinene ozonolysis. The OH-initiated oxidation of nopinone will contribute to the formation of terpenylic acid and C9H14O5 compounds during the aging of β-pinene SOA. A formation mechanism for terpenylic acid via gas-phase diaterpenylic acid formation followed by self-dehydration in the condensed phase was suggested.

  11. Distribution of {delta}{sup 14}C in western North Pacific and tracing carbons of human origin

    Energy Technology Data Exchange (ETDEWEB)

    Aramaki, Takafumi; Mizushima, Toshihiko; Togawa, Orihiko [Japan Atomic Energy Research Inst., Mutsu, Aomori (Japan). Mutsu Establishment; Watanabe, Shuichi; Tsunogai, Shizuo [Hokkaido Univ., Sapporo (Japan); Kuji, Tomoyuki [Japan marine Sience Fundation, Mutsu, Aomori (Japan)

    2001-02-01

    Seawater were collected at six points, 0deg to 48degN around 165degE. Dissolved inorganic carbonates was reduced into graphite. The ratio C-11/C-12 was measured by the accelerator mass analyzer. {sup 14}C concentration was calculated from {delta}{sup 13}C value calculated from the {sup 13}C/{sup 12}C ratio. {sup 14}C resulting from the nuclear weapon test was calculated by comparing estimated {sup 14}C and real {sup 14}C concentration. It was compared with that in 1970s. {sup 14}Cbomb has dissolved into North Pacific Intermediate Water in Arctic latitude, which has moved to Mid-latitude. (A. Yamamoto)

  12. Magnetic resonance and optical study of carbonized silica obtained bypyrolysis of surface compounds

    Czech Academy of Sciences Publication Activity Database

    Savchenko, Dariia; Kalabukhova, E.; Sitnikov, A.; Vasin, A.V.; Starik, S.; Gontar, O.; Rudko, G.; Nazarov, A.N.; Lysenko, V.S.; Tertykh, V.

    Zurich: Trans Tech Publications, 2014 - (Nazarov, A.; Lysenko, V.; Flandre, D.), s. 99-104. (Advanced Materials Research. 854). ISBN 9783037859421. ISSN 1022-6680. [International Workshop on Functional Nanomaterials and Devices /7./. Kyiv (UA), 08.04.2013-11.04.2013] R&D Projects: GA MŠk(CZ) LM2011029 Grant ostatní: SAFMAT(XE) CZ.2.16/3.1.00/22132 Institutional support: RVO:68378271 Keywords : carbonized silica nanopowders * annealing * EPR * carbon radicals * PL * IR absorption Subject RIV: BM - Solid Matter Physics ; Magnetism

  13. Source characterization using compound composition and stable carbon isotope ratio of PAHs in sediments from lakes, harbor, and shipping waterway

    International Nuclear Information System (INIS)

    Molecular compositions and compound specific stable carbon isotope ratios of polycyclic aromatic hydrocarbons (PAH) isolated from sediments were used to characterize possible sources of contamination at an urban lake, a harbor, a shipping waterway, and a relatively undisturbed remote lake in the northwest United States. Total PAH concentrations in urban lake sediments ranged from 66.0 to 16,500 μg g-1 dry wt. with an average of 2600 μg g-1, which is ∼ 50, 100, and 400 times higher on average than PAH in harbor (48 μg g-1 on average), shipping waterway (26 μg g-1), and remote lake (7 μg g-1) sediments, respectively. The PAH distribution patterns, methyl phenanthrene/phenanthrene ratios, and a pyrogenic index at the sites suggest a pyrogenic origin for PAHs. Source characterization using principal component analysis and various molecular indices including C2-dibenzothiophenes/C2-phenanthrenes, C3-dibenzothiophenes/C3-phenanthrenes, and C2-chrysenes/C2-phenanthrenes ratios, was able to differentiate PAH deposited in sediments from the four sites. The uniqueness of the source of the sediment PAHs from urban lake was also illustrated by compound specific stable carbon isotope analysis. It was concluded that urban lake sediments are accumulating PAH from sources that are unique from contamination detected at nearby sites in the same watershed

  14. Controlling the number of walls in multi walled carbon nanotubes/alumina hybrid compound via ball milling of precipitate catalyst

    Science.gov (United States)

    Nosbi, Norlin; Akil, Hazizan Md

    2015-06-01

    This paper reports the influence of milling time on the structure and properties of the precipitate catalyst of multi walled carbon nanotubes (MWCNT)/alumina hybrid compound, produced through the chemical vapour deposition (CVD) process. For this purpose, light green precipitate consisted of aluminium, nickel(II) nitrate hexahydrate and sodium hydroxide mixture was placed in a planetary mill equipped with alumina vials using alumina balls at 300 rpm rotation speed for various milling time (5-15 h) prior to calcinations and CVD process. The compound was characterized using various techniques. Based on high-resolution transmission electron microscopy analysis, increasing the milling time up to 15 h decreased the diameter of MWCNT from 32.3 to 13.1 nm. It was noticed that the milling time had a significant effect on MWCNT wall thickness, whereby increasing the milling time from 0 to 15 h reduced the number of walls from 29 to 12. It was also interesting to note that the carbon content increased from 23.29 wt.% to 36.37 wt.% with increasing milling time.

  15. Comparison of Bulk and Compound-Specific Carbon Isotope Analyses and Determination of Carbon Sources to Salt Marsh Sediments Using n-Alkane Distributions (Maine, USA)

    Science.gov (United States)

    Tanner, B. R.; Uhle, M. E.; Kelley, J. T.; Mora, C. I.

    2005-12-01

    Sources of sedimentary organic matter to a Morse River, Maine (USA) salt marsh over the last 3390+/-60 RCYBP are determined using distribution patterns of n-alkanes as well as bulk and compound-specific carbon isotopic analysis. Marsh foraminiferal counts indicate the ubiquitous presence of zone 1B deposits, suggesting that the deposits were laid down ~0.2 to 0.5m above mean high water. Distributions of n-alkanes show a primary contribution from higher plants, confirmed by an average ACL value of 27.5 for the core sediments and CPI values above 3. Many sample depths have a maximum abundance at the C25 alkane. Ten low marsh, high marsh, and higher-high marsh plant species common to Maine salt marshes were sampled, including Spartina alterniflora, Spartina patens, Juncus gerardi and Solidago sempervirens. The ACL value for the average of the 10 marsh species is 29.1. Salicornia europa, usually not considered to be a dominant species in Maine marshes, has a similar n-alkane distribution to many of the salt marsh sediments, suggesting that it is an important source to the biomass of the marsh through time. Bacterial degradation or algal inputs to the marsh sediments appear to be minor. Compound specific carbon isotopic analyses of the C27 alkanes are, on average, 7.2ppt. depleted relative to bulk values, but the two records are strongly correlated (R2 = 0.87), suggesting that marsh plants are "swamping" the bulk carbon isotopic signal. The apparent abundance of a subordinate (though common) salt marsh plant species (Salicornia europa) within our core underscores the importance of using caution when applying mixing models of relatively few plant species to marsh sediments.

  16. Carbon and Oxygen Isotopic Stratigraphy of Mesoproterozoic Carbonate Sequences (1.6–1.4 Ga from Yanshan in North China

    Directory of Open Access Journals (Sweden)

    Kuang Hongwei

    2011-01-01

    Full Text Available In Yanshan, located in the northern part of North China, Mesoproterozoic carbonate sequences (1.6–1.4 Ga form a 10, 000 m thick succession in an aulacogen basin. Carbon and oxygen isotope (δ13O and δ18O, resp. data were obtained from 110 carbonate samples across three sections of these Mesoproterozoic deposits. From the early to late Mesoproterozoic, low negative values of δ13O appear, followed by low positive variation and then a stable increase. An abrupt decrease in δ13O values, with subsequent rapid increase, is found at the end of the Mesoproterozoic. During the whole Mesoproterozoic, δ18O shows a mainly negative trend and occasional highly negative isotopic shifts (from lower to upper deposits. Whole-rock carbon and oxygen isotopic compositions and profiles must be studied to provide a paleogeochemical record that can be associated with paleocean sedimentary environments, temperature, biological productivity, and sea-level fluctuations. Results of the present study correlate well with other international carbon and oxygen isotope profiles, suggesting that a global marine geochemical system existed during the interval of 1.6–1.4 Ga under a globally united tectonic, sedimentary, and geochemical background.

  17. Multimolecular tracers of terrestrial carbon transfer across the pan-Arctic: 14C characteristics of sedimentary carbon components and their environmental controls

    Science.gov (United States)

    Feng, Xiaojuan; Gustafsson, Örjan; Holmes, R. Max; Vonk, Jorien E.; Dongen, Bart E.; Semiletov, Igor P.; Dudarev, Oleg V.; Yunker, Mark B.; Macdonald, Robie W.; Wacker, Lukas; Montluçon, Daniel B.; Eglinton, Timothy I.

    2015-11-01

    Distinguishing the sources, ages, and fate of various terrestrial organic carbon (OC) pools mobilized from heterogeneous Arctic landscapes is key to assessing climatic impacts on the fluvial release of carbon from permafrost. Through molecular 14C measurements, including novel analyses of suberin- and/or cutin-derived diacids (DAs) and hydroxy fatty acids (FAs), we compared the radiocarbon characteristics of a comprehensive suite of terrestrial markers (including plant wax lipids, cutin, suberin, lignin, and hydroxy phenols) in the sedimentary particles from nine major arctic and subarctic rivers in order to establish a benchmark assessment of the mobilization patterns of terrestrial OC pools across the pan-Arctic. Terrestrial lipids, including suberin-derived longer-chain DAs (C24,26,28), plant wax FAs (C24,26,28), and n-alkanes (C27,29,31), incorporated significant inputs of aged carbon, presumably from deeper soil horizons. Mobilization and translocation of these "old" terrestrial carbon components was dependent on nonlinear processes associated with permafrost distributions. By contrast, shorter-chain (C16,18) DAs and lignin phenols (as well as hydroxy phenols in rivers outside eastern Eurasian Arctic) were much more enriched in 14C, suggesting incorporation of relatively young carbon supplied by runoff processes from recent vegetation debris and surface layers. Furthermore, the radiocarbon content of terrestrial markers is heavily influenced by specific OC sources and degradation status. Overall, multitracer molecular 14C analysis sheds new light on the mobilization of terrestrial OC from arctic watersheds. Our findings of distinct ages for various terrestrial carbon components may aid in elucidating fate of different terrestrial OC pools in the face of increasing arctic permafrost thaw.

  18. Optimization of liquid scintillation counting techniques for the determination of carbon-14 in environmental samples

    International Nuclear Information System (INIS)

    The goal of this work was to optimize the liquid scintillation counting techniques for the determination of 14C in stack effluent gases and in environmental samples such as biological and air samples. Carbon-14 activities in most environmental samples were measured with the direct CO2 absorption method. The highest figures of merit were found through the variation of Carbosorb E and Permafluor V ratio, and measurement windows. The best condition was an 1:1 volume ratio. Average 2.35 g of CO2 was reproducibly absorbed in the 20 ml mixture within 40 minutes. The counting efficiency determined by repeated analysis of NIST oxalic acid standard and the background count rate were measured to be 58.8±1.4% and 1.88±0.06 cpm, respectively, in case of saturated solution. The correction curves of counting efficiency for partially saturated solutions and for saturated solutions with quenching were prepared, respectively. The overall uncertainty of the sample specific activity for near background levels was estimated to be about 7% for 4 hours counting at 95% confidence level. Stack effluent gas samples were measured by a gel suspension counting method. After precipitation of CO2 in the form of BaCO3, 140 mg of which was mixed with 6 ml H2O and 12 ml of Instagel XF. The counting efficiency was measured to be 71.5±1.7% and the typical sensitivity of this technique was about 510 mBq/m3 for a 100 min count at a background count rate of 4.7 cpm. For the benzene counting method measurements were performed with a mixture of 3 ml benzene and 1 ml of scintillation cocktail (5 g of butyl-PBD in 100 ml of scintillation-grade toluene) in a low potassium 7 ml borosilicate glass vial. The counting efficiency and the background count rate were measured to be 64.3±1.0% and 0.51±0.05 cpm, respectively. The long-term stability of samples has been checked for all the counting techniques over a two week period, during which no apparent change in counting efficiency and background level was

  19. A review of volatile compounds in tektites, and carbon content and isotopic composition of moldavite glass

    Czech Academy of Sciences Publication Activity Database

    Žák, Karel; Skála, Roman; Řanda, Zdeněk; Mizera, Jiří

    2012-01-01

    Roč. 47, č. 6 (2012), s. 1010-1028. ISSN 1086-9379 R&D Projects: GA ČR GA205/09/0991 Institutional research plan: CEZ:AV0Z30130516; CEZ:AV0Z10480505 Keywords : moldavites * geochemistry * ries * carbon stable isotopes * moldavites (Germany) Subject RIV: DD - Geochemistry Impact factor: 2.800, year: 2012

  20. Charcoal and activated carbon as adsorbate of phytotoxic compounds - a comparative study.

    NARCIS (Netherlands)

    Hille, M.G.; Ouden, den J.

    2005-01-01

    This study compares the potential of natural charcoal from Scots pine (Pinus sylvestris L.) and activated carbon to improve germination under the hypothesis that natural charcoal adsorbs phytotoxins produced by dwarf-shrubs, but due to it's chemical properties to a lesser extent than activated carbo

  1. The history of ironware in Japan revealed by the AMS-carbon 14 age method

    International Nuclear Information System (INIS)

    This paper focuses on the influence what the AMS-carbon 14 age method attains to the history of the iron in the Japanese Islands. The research team in National Museum of Japanese History makes a clear that the Yayoi period began in 10 Cen. cal BC. However, there was a problem in this. It is iron. If the Yayoi period has started in the 10th Cen. BC, it means that the ironware in Japanese Islands had spread early rather than it spreads in China. The research team reexamined the ironware excavated from Magarita site in the Fukuoka Pref. considered to be the oldest ironware in Japan. Consequently, the excavation situation was indefinite and it turned out that we cannot specify the time to belong. Furthermore, 36 ironwares in the initial and early Yayoi were also already found by that time cannot be specified except for two points. Therefore, it turned out that Japanese ironware appeared in the 3rd century of B.C. What does this mean? Although it had been thought that the beginning of agriculture in Japan and the appearance of ironware were simultaneous, it turned out that agriculture has appeared early about in 700 years. Therefore, it became clear that agriculture of Japan started at the Stone Age. (author)

  2. Automatic counting and recording unit used for dating by the carbon 14 method

    International Nuclear Information System (INIS)

    A description is given of the unit used by the 'Centre Scientifique de Monaco' for low-level beta counting and fitted for radioactive dating by the Carbon 14 method. Built entirely by the laboratory in 1964, on the basis of electronic techniques then recent, it has worked without failure since that time. The proportional counter, its high-voltage negative supply, and the counting chains with visual and printing records are detailed by means of 38 figures which reproduce the counter and the electronic circuits. These are contained in two standard 5 U.I structures. The low-voltage power supply of the whole unit is carried out by plus 12 volts and minus 12 volts storage batteries, buffered on a charger connected on the 110 V alternative line. The proportional counter described is filled with CO2 under one atmosphere pressure and permits the dating of carbonaceous samples with a maximum of 30.000 + 1.000 years (background 3.96 c.p.m. ) within a moderate time (72 hours). (authors)

  3. Self assembled rotaxane and pseudo-rotaxanes based on β-cyclodextrin inclusion compounds with trans-1,4-bis[(4-pyridyl)ethenyl]benzene-pentacyanoferrate(II) complexes

    International Nuclear Information System (INIS)

    Inclusion compounds of trans-1,4-bis[(4-pyridyl)ethenyl]benzene (BPEB) and their corresponding pentacyanoferrate(II) complexes with β-cyclodextrin have been studied in aqueous solution by 1H NMR and UV-Visible spectroscopy. All the inclusion compounds exhibit 1:1 stoichiometry is aqueous solution. In the presence of β-cyclodextrin, the binuclear {[Fe(CN)5]2(BPEB)]6- complex is gradually converted into rotaxane species bearing [Fe(CN)5]3- end groups, by a self assembly inclusion mechanism, as confirmed by 1H NMR spectroscopy. (author)

  4. Synthesis and Structure of a Novel Supramolecular Compound [Co(2,2'-bipy)(H2 O)4 ][trans-1,4-chdc] and Separation of Isomer of 1,4-Cyclohexanedicarboxylic Acid

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A supramolecular compound, [Co(2,2'-bipy)(H2O)4][trans-1,4-chdc] (compound 1) (2,2'-bipy=2,2'-bipyridine, 1,4-chdcH2=1,4-cyclohexanedicarboxylic acid), was synthesized and characterized by single-crystal X-ray diffraction analysis, IR spectrometry, TG analysis, and elemental analyses. Single-crystal X-ray diffraction analysis revealed that [Co(2,2'-bipy)(H2O)4]2+ units and adjacent 1,4-chdc2- formed a single layer by hydrogen bonding and electrostatic interactions along the ac-plane, and two symmetry-related single layers interacted with each other by hydrogen bonding, resulting in a double layer, which further formed a 3-D structure by π-π stacking. The most attractive structural feature of compound 1 is that 1,4-chdc2- possesses only trans-conformation although there are both cis- and trans-conformations in the raw material.

  5. Optimizing sample pretreatment for compound-specific stable carbon isotopic analysis of amino sugars in marine sediment

    Directory of Open Access Journals (Sweden)

    R. Zhu

    2014-01-01

    Full Text Available Amino sugars are quantitatively significant constituents of soil and marine sediment, but their sources and turnover in environmental samples remain poorly understood. The stable carbon isotopic composition of amino sugars can provide information on the lifestyles of their source organisms and can be monitored during incubations with labeled substrates to estimate the turnover rates of microbial populations. However, until now, such investigation has been carried out only with soil samples, partly because of the much lower abundance of amino sugars in marine environments. We therefore optimized a procedure for compound-specific isotopic analysis of amino sugars in marine sediment employing gas chromatography-isotope ratio mass spectrometry. The whole procedure consisted of hydrolysis, neutralization, enrichment, and derivatization of amino sugars. Except for the derivatization step, the protocol introduced negligible isotopic fractionation, and the minimum requirement of amino sugar for isotopic analysis was 20 ng, i.e. equivalent to ~ 8 ng of amino sugar carbon. Our results obtained from δ13C analysis of amino sugars in selected marine sediment samples showed that muramic acid had isotopic imprints from indigenous bacterial activities, whereas glucosamine and galactosamine were mainly derived from organic detritus. The analysis of stable carbon isotopic compositions of amino sugars opens a promising window for the investigation of microbial metabolisms in marine sediments and the deep marine biosphere.

  6. Validation of a simplified carbon-14-urea breath test for routine use for detecting Helicobacter pylori noninvasively

    International Nuclear Information System (INIS)

    A carbon-14 (14C) urea breath test for detecting Helicobacter pylori with multiple breath sampling was developed. Carbon-14-urea (110 kBq) administered orally to 18 normal subjects and to 82 patients with Helicobacter infection. The exhaled 14C-labeled CO2 was trapped at 10-min intervals for 90 min. The total 14C activity exhaled over 90 min was integrated and expressed in %activity of the total dose given. In normals, a mean of 0.59% +/- 0.24% was measured, resulting in an upper limit of normal of 1.07%. In 82 patients, a sensitivity of 90.2%, a specificity of 83.8%, and a positive predictive value of 90.2% was found. The single probes at intervals of 40-60 min correlated best with the integrated result, with r ranging from 0.986 to 0.990. The test's diagnostic accuracy did not change at all when reevaluated with the 40-, 50-, or 60-min sample data alone. Thus, the 14C-urea breath test can be applied routinely as a noninvasive, low-cost and one-sample test with high diagnostic accuracy in detecting Helicobacter pylori colonization

  7. Isolation of Bioactive Compounds from Sunflower Leaves (Helianthus annuus L.) Extracted with Supercritical Carbon Dioxide.

    Science.gov (United States)

    El Marsni, Zouhir; Torres, Ascension; Varela, Rosa M; Molinillo, José M G; Casas, Lourdes; Mantell, Casimiro; Martinez de la Ossa, Enrique J; Macias, Francisco A

    2015-07-22

    The work described herein is a continuation of our initial studies on the supercritical fluid extraction (SFE) with CO2 of bioactive substances from Helianthus annuus L. var. Arianna. The selected SFE extract showed high activity in the wheat coleoptile bioassay, in Petri dish phytotoxicity bioassays, and in the hydroponic culture of tomato seeds. Chromatographic fractionations of the extracts and a spectroscopic analysis of the isolated compounds showed 52 substances belonging to 10 different chemical classes, which were mainly sesquiterpene lactones, diterpenes, and flavonoids. Heliannuol M (31), helivypolides K and L (36, 37), and helieudesmanolide B (38) are described for the first time in the literature. Metabolites have been tested in the etiolated wheat coleoptile bioassay with good results in a noteworthy effect on germination. The most active compounds were also tested on tomato seeds, heliannuol A (30) and leptocarpin (45) being the most active, with values similar to those of the commercial herbicide. PMID:26151222

  8. The stopping power and carbon ion ranges in elements and compounds

    International Nuclear Information System (INIS)

    Possibility of the heavy ions stopping cross sections calculation are discussed. The stopping ppower and C12 ions ranges are evaluated using the protons stopping data in matter and Pirson's and Blanns formula for the effectvive charge. The energy losses due to the elastic collisions with atoms have been taken into account in low energies. The RBregg's rule was used to calculate the stopping power of compounds. The comparison with the evailable data showed a good agreement. The C12 ions ranges with energies from 0.01 to 10 NMeV/nucleon for elements from hydrogen to uranium and several compounds are tabulated. The C12 ions energy losses in the layers of definite thickness can be determined using these tables

  9. Quantum efficiency of energy transfer in noncovalent carbon nanotube/porphyrin compounds

    OpenAIRE

    Roquelet, Cyrielle; Garrot, Damien; Lauret, Jean-Sébastien; Voisin, C.; Alain-Rizzo, Valérie; Roussignol, Philippe; Delaire, Jacques,; Deleporte, Emmanuelle

    2010-01-01

    We report on the quantum yield of excitation energy transfer in non-covalently bound nan- otube/porphyrin compounds. Evidence for energy transfer is gained from photoluminescence exci- tation experiments. We perform a quantitative evaluation of the transfer quantum yield in the case of (6,5) nanotubes through three independent methods : quantitative PLE measurements, evalu- ation of the luminescence quenching of the donor (porphyrin) and ultrafast transient absorption measurements. The latter...

  10. Carbon transfer between 2 1/4 Cr 1 Mo alloy and austenitic steels (experiments in anisothermal loops)

    International Nuclear Information System (INIS)

    Studies on carbon transfer between the ferritic steel 2 1/4 Cr 1 Mo and the austenitic steels 316L and 321H have shown that there is not any measurable carbon transfer in the operating conditions of the secondary circuit of PHENIX (475 deg C was the maximal temperature of the 2 1/4 Cr 1 Mo steel). A significant carbon transfer has been observed between the ferritic steel and the 316L steel when the 321H was replaced by the 2 1/4 Cr 1 Mo steel in the same thermohydraulic conditions (the ferritic steel was then used up to 545 deg C). This experiment has demonstrated the importance of the temperature and the initial carbon content of the ferritic steel as parameters in the decarburization process. It appears that decarburization may not be sensitive to the thermohydraulic conditions at least in the range investigated in those experiments. In the other hand the 316L steel is observed to have been carburized, the degree of carburization remaining appreciably constant and independent on the temperature between 400 deg C and 550 deg C

  11. Evaluation of two decomposition schemes in Earth System Models against LIDET, C14 observations and global soil carbon maps

    Science.gov (United States)

    Ricciuto, D. M.; Yang, X.; Thornton, P. E.

    2015-12-01

    Soils contain the largest pool of carbon in terrestrial ecosystems. Soil carbon dynamics and associated nutrient dynamics play significant roles in regulating global carbon cycle and atmospheric CO2 concentrations. Our capability to predict future climate change depends to a large extent on a well-constrained representation of soil carbon dynamics in ESMs. Here we evaluate two decomposition schemes - converging trophic cascade (CTC) and Century - in CLM4.5/ACME V0 using data from the long-term intersite decomposition experiment team (LIDET), radiocarbon (14C) observations, and Harmonized World Soil Database (HWSD). For the evaluation against LIDET, We exercise the full CLM4.5/ ACME V0 land model, including seasonal variability in nitrogen limitation and environmental scalars (temperature, moisture, O2), in order to represent LIDET experiment in a realistic way. We show that the proper design of model experiments is crucial to model evaluation using data from field experiments such as LIDET. We also use 14C profile data at 10 sites to evaluate the performance of CTC and CENTURY decomposition scheme. We find that the 14C profiles at these sites are most sensitive to the depth dependent decomposition parameters, consistent with previous studies.

  12. Manipulating Ce Valence in RE2Fe14B Tetragonal Compounds by La-Ce Co-doping: Resultant Crystallographic and Magnetic Anomaly

    Science.gov (United States)

    Jin, Jiaying; Zhang, Yujing; Bai, Guohua; Qian, Zeyu; Wu, Chen; Ma, Tianyu; Shen, Baogen; Yan, Mi

    2016-01-01

    Abundant and low-cost Ce has attracted considerable interest as a prospective alternative for those critically relied Nd/Pr/Dy/Tb in the 2:14:1-type permanent magnets. The (Nd, Ce)2Fe14B compound with inferior intrinsic magnetic properties to Nd2Fe14B, however, cannot provide an equivalent magnetic performance. Since Ce valence is sensitive to local steric environment, manipulating it towards the favorable trivalent state provides a way to enhance the magnetic properties. Here we report that such a desirable Ce valence can be induced by La-Ce co-doping into [(Pr, Nd)1−x(La, Ce)x]2.14Fe14B (0 ≤ x ≤ 0.5) compounds via strip casting. As verified by X-ray photoelectron spectroscopy results, Ce valence shifts towards the magnetically favorable Ce3+ state in the composition range of x > 0.3, owing to the co-doping of large radius La3+ into 2:14:1 phase lattice. As a result, both crystallographic and magnetic anomalies are observed in the same vicinity of x = 0.3, above which lattice parameters a and c, and saturation magnetization Ms increase simultaneously. Over the whole doping range, 2:14:1 tetragonal structure forms and keeps stable even at 1250 K. This finding may shed light on obtaining a favorable Ce valence via La-Ce co-doping, thus maintaining the intrinsic magnetic properties of 2:14:1-type permanent magnets. PMID:27457408

  13. Manipulating Ce Valence in RE2Fe14B Tetragonal Compounds by La-Ce Co-doping: Resultant Crystallographic and Magnetic Anomaly.

    Science.gov (United States)

    Jin, Jiaying; Zhang, Yujing; Bai, Guohua; Qian, Zeyu; Wu, Chen; Ma, Tianyu; Shen, Baogen; Yan, Mi

    2016-01-01

    Abundant and low-cost Ce has attracted considerable interest as a prospective alternative for those critically relied Nd/Pr/Dy/Tb in the 2:14:1-type permanent magnets. The (Nd, Ce)2Fe14B compound with inferior intrinsic magnetic properties to Nd2Fe14B, however, cannot provide an equivalent magnetic performance. Since Ce valence is sensitive to local steric environment, manipulating it towards the favorable trivalent state provides a way to enhance the magnetic properties. Here we report that such a desirable Ce valence can be induced by La-Ce co-doping into [(Pr, Nd)1-x(La, Ce)x]2.14Fe14B (0 ≤ x ≤ 0.5) compounds via strip casting. As verified by X-ray photoelectron spectroscopy results, Ce valence shifts towards the magnetically favorable Ce(3+) state in the composition range of x > 0.3, owing to the co-doping of large radius La(3+) into 2:14:1 phase lattice. As a result, both crystallographic and magnetic anomalies are observed in the same vicinity of x = 0.3, above which lattice parameters a and c, and saturation magnetization Ms increase simultaneously. Over the whole doping range, 2:14:1 tetragonal structure forms and keeps stable even at 1250 K. This finding may shed light on obtaining a favorable Ce valence via La-Ce co-doping, thus maintaining the intrinsic magnetic properties of 2:14:1-type permanent magnets. PMID:27457408

  14. Measurement of Carbon Fixation Rates in Leaf Samples — Use of carbon-14 labeled sodium bicarbonate to estimate photosynthetic rates

    OpenAIRE

    sprotocols

    2014-01-01

    Author: David R. Caprette ### Generation of a Light Curve To address the hypothesis concerning photosynthetic efficiency it is necessary to expose sun and shade leaves to a range of light intensities long enough for them to fix significant amounts of carbon. It is necessary to expose identical surface areas under favorable conditions which are identical for all leaves except for light intensity (the experimental variable). A means of measuring the rate of carbon fixation is also neces...

  15. The role of neutral and radical anionic organozinc complexes in the alkylation reactions of 1,4-diaza-1,3-butadienes with diorganozinc compounds

    OpenAIRE

    van Koten, G; Rijnberg, E.; Boersma, J.; Jastrzebski, J.T.B.H.; Lakin, M.T.; Spek, A.L.

    1997-01-01

    We have earlier postulated the intermediacy of organozinc radical species in the regioselective alkylation reactions of 1,4-di-tert-butyl-1,4-diaza-1,3-butadiene (t-BuNCHCHN-t-Bu) with diorganozinc compounds (ZnR2). To verify these postulates, we have prepared and studied the neutral organozinc radical complex MeO(CH2)3Zn(t-BuNCHCHN-t-Bu) (A) and two diorganozinc radical-anionic complexes, K[R2Zn(t-BuNCHCHN-t-Bu)] (R = Me (8a), Et (8b)). A was prepared in situ by the reaction of t-BuNCHCHN-t-...

  16. Evaluation of carbon-14 (C14) levels of terrestrial and marine food products of the environment of the site of Cogema La Hague

    International Nuclear Information System (INIS)

    This evaluation has for object to inform about the levels in carbon 14 in the environment of the factories of La Hague. Two sectors were differentiated on one hand the terrestrial environment, and on the other hand the marine environment. The investigations concerned first and foremost food products stemming as the vegetable culture (vegetables) or individual breeding (milk, eggs) but also foodstuffs stemming from the local agriculture (cereal). In touch with the second sector, the marine environment, the sampling concerned the accessible products of the sea by all and those locally marketed (fishes, molluscs, shellfishes). The different results are presented in tables. (N.C.)

  17. The crystal structure and physicochemical characteristics of 2-hydroxy-N-[3(5)-pyrazolyl]-1,4-naphthoquinone-4-imine, a new antitrypanosomal compound

    OpenAIRE

    Sperandeo, Norma R.; Karlsson, Alicia; Cuffini, Silvia; Pagola, Silvina; Stephens, Peter W.

    2005-01-01

    This study was designed to investigate the physical characteristics and crystalline structure of 2-hydroxy-N-[3(5)-pyrazolyl]-1,4-naphthoquinone-4-imine (PNQ), a new active compound againstTrypanosoma cruzi, the causative agent of American trypanosomiasis. Methods used included differential scanning calorimetry, thermogravimetry, hot stage microscopy, polarized light microscopy (PLM), Fourier-transform infrared (FTIR) spectroscopy, and high-resolution X-ray powder diffraction (HR-XRPD). Accor...

  18. The 1,4-diazabutadiene/1,2-enediamido non-innocent ligand system in the formation of iridaheteroaromatic compounds: Spectroelectrochemistry and electronic structure

    Czech Academy of Sciences Publication Activity Database

    Kaim, A.; Sieger, M.; Greulich, S.; Sarkar, B.; Fiedler, Jan; Záliš, Stanislav

    2010-01-01

    Roč. 695, č. 7 (2010), s. 1052-1058. ISSN 0022-328X R&D Projects: GA AV ČR KAN100400702; GA MŠk OC 139; GA MŠk OC09043 Institutional research plan: CEZ:AV0Z40400503 Keywords : 1,4-diazabutadiene * electron ic structure * iridium compounds Subject RIV: CG - Electrochemistry Impact factor: 2.205, year: 2010

  19. Biosynthesis of monobactam compounds: origin of the carbon atoms in the beta-lactam ring.

    OpenAIRE

    O'Sullivan, J; Gillum, A M; Aklonis, C A; Souser, M L; Sykes, R. B.

    1982-01-01

    The biosynthesis of monobactams by strains of Chromobacterium violaceum, Acetobacter sp., and Agrobacterium radiobacter was studied. Monobactams were produced during logarithmic growth by C. violaceum and Acetobacter sp. and during late log growth on glycerol and in stationary phase by A. radiobacter. The addition of various amino acids failed to significantly stimulate monobactam production in any of the producing organisms. Several 14C-amino acids and pyruvate were incorporated in vivo into...

  20. Radiocarbon dating of organic compounds in sediments using preparative capillary gas chromatography (PCGC)

    Energy Technology Data Exchange (ETDEWEB)

    Uchida, Masao [Japan Marine Science and Technology Center, Yokosuka, Kanagawa (Japan); Shibata, Yasuyuki; Yoneda, Minoru; Mukai, Hitoshi; Tanaka, Atsushi; Uehiro, Takashi; Morita, Masatoshi [National Inst. for Environmental Studies, Tsukuba, Ibaraki (Japan); Kawamura, Kimitaka [Hokkaido Univ., Sapporo (Japan); Hirota, Masashi [National Inst. for Environmental Studies, Tsukuba, Ibaraki (Japan)

    2001-02-01

    CG-AMS system, combining two-dimensional gas chromatography and accelerator mass spectroscopy, has been developed for compound-specific carbon 14 measurement. Samples from shallow sea sediments in Sanbanse, Tokyo bay ware collected, six typical fatty acids were separated therefrom. Ages were estimated from the carbon 14 measurement. Acids of carbon number 15 and 16 has nearly contemporary age, whereas acids of carbon number 22 has age of 17000 years. (A. Yamamoto)

  1. Effect of Functional Group and Carbon Chain Length on the Odor Detection Threshold of Aliphatic Compounds

    Directory of Open Access Journals (Sweden)

    Manuel Zarzo

    2012-03-01

    Full Text Available Odor detection thresholds (ODTs are used for assessing outdoor and indoor air quality. They are obtained experimentally by olfactometry and psychophysical methods, and large compilations are available in the literature. A non-linear regression equation was fitted to describe the ODT variability of 114 aliphatic compounds based on the alkyl chain length for different homologous series (carboxylic acids, aldehydes, 2-ketones, esters, 1-alcohols, amines, thiols, thioethers and hydrocarbons. The resulting equation reveals an effect of the functional group, molecular size and also an interaction between both factors. Although the mechanistic interpretation of results is uncertain, the relatively high goodness-of-fit (R2 = 0.90 suggests that ODT values of aliphatic compounds can be predicted rather accurately, which is not the case for rigid molecules. This equation may serve as a basis for the development of more complex ODT models taking into account diverse structural features of odorants. The variability of power-law exponents was also investigated for the homologous series.

  2. Biochar, activated carbon, and carbon nanotubes have different effects on fate of 14C-catechol and microbial community in soil

    Science.gov (United States)

    Shan, Jun; Ji, Rong; Yu, Yongjie; Xie, Zubin; Yan, Xiaoyuan

    2015-10-01

    This study investigated the effects of biochar, activated carbon (AC)-, and single-walled and multi-walled carbon nanotubes (SWCNTs and MWCNTs) in various concentrations (0, 0.2, 20, and 2,000 mg/kg dry soil) on the fate of 14C-catechol and microbial community in soil. The results showed that biochar had no effect on the mineralization of 14C-catechol, whereas AC at all amendment rates and SWCNTs at 2,000 mg/kg significantly reduced mineralization. Particularly, MWCNTs at 0.2 mg/kg significantly stimulated mineralization compared with the control soil. The inhibitory effects of AC and SWCNTs on the mineralization were attributed to the inhibited soil microbial activities and the shifts in microbial communities, as suggested by the reduced microbial biomass C and the separated phylogenetic distance. In contrast, the stimulatory effects of MWCNTs on the mineralization were attributed to the selective stimulation of specific catechol-degraders by MWCNTs at 0.2 mg/kg. Only MWCNTs amendments and AC at 2,000 mg/kg significantly changed the distribution of 14C residues within the fractions of humic substances. Our findings suggest biochar, AC, SWCNTs and MWCNTs have different effects on the fate of 14C-catechol and microbial community in soil.

  3. The present status of carbon 14 analysis and projects for beryllium 10 analysis at the Tandetron 1 accelerator, Nagoya University

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Toshio; Oda, Hirotaka; Ikeda, Akiko; Niu, Etsuko [Nagoya Univ. (Japan)

    2001-02-01

    The operation experience in 1999 of the Tandetron accelerator age estimation system, Nagoya University, is reported, after the overview and the history of the accelerator is briefly described. Total number of carbon 14 environmental samples analyzed was 8567. The project of introducing new HVEE Tandetron for C-14 analysis, and modifying the present GIC Tandetron for Be-10 analysis is presented. Ion source shall be replaced, and the heavy ion detector shall be installed. Projected geological and archaeological studies using Be-10 are enumerated. (A. Yamamoto)

  4. Bayesian calibration of a soil organic carbon model using Δ14C measurements of soil organic carbon and heterotrophic respiration as joint constraints

    Science.gov (United States)

    Ahrens, B.; Reichstein, M.; Borken, W.; Muhr, J.; Trumbore, S. E.; Wutzler, T.

    2014-04-01

    Soils of temperate forests store significant amounts of organic matter and are considered to be net sinks of atmospheric CO2. Soil organic carbon (SOC) turnover has been studied using the Δ14C values of bulk SOC or different SOC fractions as observational constraints in SOC models. Further, the Δ14C values of CO2 that evolved during the incubation of soil and roots have been widely used together with Δ14C of total soil respiration to partition soil respiration into heterotrophic respiration (HR) and rhizosphere respiration. However, these data have not been used as joint observational constraints to determine SOC turnover times. Thus, we focus on (1) how different combinations of observational constraints help to narrow estimates of turnover times and other parameters of a simple two-pool model, the Introductory Carbon Balance Model (ICBM); (2) whether relaxing the steady-state assumption in a multiple constraints approach allows the source/sink strength of the soil to be determined while estimating turnover times at the same time. To this end ICBM was adapted to model SOC and SO14C in parallel with litterfall and the Δ14C of litterfall as driving variables. The Δ14C of the atmosphere with its prominent bomb peak was used as a proxy for the Δ14C of litterfall. Data from three spruce-dominated temperate forests in Germany and the USA (Coulissenhieb II, Solling D0 and Howland Tower site) were used to estimate the parameters of ICBM via Bayesian calibration. Key findings are as follows: (1) the joint use of all four observational constraints (SOC stock and its Δ14C, HR flux and its Δ14C) helped to considerably narrow turnover times of the young pool (primarily by Δ14C of HR) and the old pool (primarily by Δ14C of SOC). Furthermore, the joint use of all observational constraints made it possible to constrain the humification factor in ICBM, which describes the fraction of the annual outflux from the young pool that enters the old pool. The Bayesian parameter

  5. Emissions to air in Sweden: sulphur dioxide, nitrogen oxides, carbon dioxide, methane, nitrous oxide, carbon monoxide and volatile organic compounds, 1999

    International Nuclear Information System (INIS)

    The method for calculating emissions to air has been revised, which has led to adjustments. Because of this, emissions in 1999 cannot yet be compared with previous years. Emissions in 1990 - 1998 are being recalculated now using the new method and are expected to be ready during 2001. Emissions to air of carbon dioxide (CO2) in Sweden was 56.58 million tonnes in 1999, not including emissions from biofuels and international bunkers. The major sources of CO2 emissions are the combustion of fossil fuels and the use of fuels for mobile sources. Total emissions to air of sulphur dioxide (SO2) and nitrogen oxides (NOx, counted as NO2) in Sweden was 66 000 and 263 000 tonnes respectively in 1999. International bunkers are not included. The major source of SO2 emissions is combustion of fossil fuels. Road traffic is the major source of NOx emissions. Emissions to air of methane (CH4), nitrous oxide (N2O), carbon monoxide (CO) and volatile organic compounds (NMVOC) in 1999 were 253 000, 26 000, 924 000 and 430 000 tonnes respectively, not including international bunkers. Agriculture is the major source of CH4 and N2O emissions. CO mainly derives from road traffic and NMVOC mainly derives from household combustion and road traffic

  6. Validation of ten-minute single sample carbon-14 urea breath test for diagnosis of Helicobacter pylori infection

    Energy Technology Data Exchange (ETDEWEB)

    Prabakaran, K.; Fernandes, V.; McDonald, J. [Illawarra Regional Hospital, Wollongong, NSW (Australia). Depts of Nuclear Medicine and Gastroenterology

    1996-09-01

    Helicobacter pylori infection is traditionally diagnosed by endoscopy followed by gastric biopsy and histologic demonstration of organisms, rapid urease test and culture. The non-invasive carbon-14-urea breath test has been widely accepted now for the diagnosis of this bacterium. This study was aimed to establish and validate normal and abnormal values for an Australian population, for a single sample carbon-14-urea breath test at ten minutes. A dose of 185 kBq was used in order to achieve reasonable counting statistics. The derived values were validated with the results of the rapid urease test. This method has a high sensitivity, specificity and greater patient acceptance, and could be used in many clinical settings as the first modality for the diagnosis of H. pylori infection and for documenting response or cure after antibiotic therapy for eradication. 11 refs., 1 tab., 4 figs.

  7. Validation of ten-minute single sample carbon-14 urea breath test for diagnosis of Helicobacter pylori infection

    International Nuclear Information System (INIS)

    Helicobacter pylori infection is traditionally diagnosed by endoscopy followed by gastric biopsy and histologic demonstration of organisms, rapid urease test and culture. The non-invasive carbon-14-urea breath test has been widely accepted now for the diagnosis of this bacterium. This study was aimed to establish and validate normal and abnormal values for an Australian population, for a single sample carbon-14-urea breath test at ten minutes. A dose of 185 kBq was used in order to achieve reasonable counting statistics. The derived values were validated with the results of the rapid urease test. This method has a high sensitivity, specificity and greater patient acceptance, and could be used in many clinical settings as the first modality for the diagnosis of H. pylori infection and for documenting response or cure after antibiotic therapy for eradication. 11 refs., 1 tab., 4 figs

  8. Unusual route for preparation of manganese(II), cobalt(II), zinc(II) and cadmium(II) carbonate compounds: synthesis and spectroscopic characterizations

    Indian Academy of Sciences (India)

    Moamen S Refat; Mohsen M Al-Qahtani

    2011-07-01

    The manganese(II) carbonate, MnCO3.H2O, cobalt(II) carbonate, CoCO3.4H2O, zinc(II) carbonate, ZnCO3 and cadmium(II) carbonate, CdCO3, respectively, were synthesis by a new simple unusual route during the reaction of aqueous solutions of MnX2, CoX2, ZnX2 and CdX2, where (X = Br- and ClO$^{-}_{4}$) with urea at high temperature within ∼ 90°C for 6 h. The infrared spectra of the reaction products clearly indicate the absence of the bands of urea, but show the characteristic bands of ionic carbonate, CO$^{2-}_{3}$. A general mechanism describing the preparation of manganese(II), cobalt(II), zinc(II) and cadmium(II) carbonate compounds are discussed.

  9. Intracellular concentrations and metabolism of carbon compounds in tobacco callus cultures: Effects of light and auxin

    Energy Technology Data Exchange (ETDEWEB)

    Lawyer, A.L.; Grady, K.L.; Bassham, J.A.

    1981-10-01

    Callus cultures derived from pith tissue of Nicotiana tobacum were grown on two media either under continuous illumination or in complete darkness. The first medium limited greening ability of callus grown in the light (3 milligrams per liter naphthalene acetic acid, 0.3 milligram per liter 2-isopentenylaminopurine, Murashige and Skoog salts, and 2% sucrose). The second medium encouraged chlorophyll synthesis (greening) though not shoot formation (0.3 milligram per liter naphthalene acetic acid; 0.3 milligrams per liter 2-isopentylaminopurine). To measure intracellular concentrations, calli were grown for 15 days on these standard media containing (U-/sup 14/C)sucrose. The dry weight proportions of the calli (as a fraction of fresh weight) and many metabolite concentrations nearly doubled in light-grown cells compared to dark-grown cells and increase 30 to 40% on low-auxin media relative to high-auxin media. Glutamine concentrations (from 4 to 26 millimolar) were very high, probably due to the NH/sub 3/ content of the media. Proline concentrations were 20-fold higher in calli grown on low-auxin media in the light (green cells), possibly a stress response to high osmotic potentials in these cells. To analyze sucrose metabolism, callus cells were allowed to take up 0.2% (weight per volume) (U-/sup 14/C)sucrose for up to 90 minutes. In callus tissues and in pith sections from stems of tobacco plants, sucrose was primarily metabolized through invertase activity, producing equal amounts of labeling glucose and fructose. Respiration of /sup 14/CO/sub 2/ followed the labeling patterns of tricarboxylic acid cycle intermediates. Photorespiration activity was low.

  10. The use of C-14 as tracer in the carbon flow assimilated by the plants (maize, sugar cane, bean)

    International Nuclear Information System (INIS)

    The flow of carbon in three different crops (maize, beans and sugar cane) was studied by use of C-14. The plants were exposed to an atmosphere with a constant concentration of the tracer for 12 hours in a biosynthesis chamber. The detection of the isotope permitted the distribution and concentration of the photosynthetates in the various organs of the plants to be followed. (M.A.C.)

  11. Photocatalytic and chemical oxidation of organic compounds in supercritical carbon dioxide. Progress report for FY97

    International Nuclear Information System (INIS)

    'The background for the project is briefly reviewed and the work done during the nine months since funding was received is documented. Work began in January, 1997. A post doctoral fellow joined the team in April. The major activities completed this fiscal year were: staffing the project, design of the experimental system, procurement of components, assembly of the system. preparation of the Safe Operating Procedure and ES and H compliance, pressure testing, establishing data collection and storage methodology, and catalyst preparation. Objective The objective of the project is to develop new chemistry for the removal of organic contaminants from supercritical carbon dioxide. This has application in processes used for continuous cleaning and extraction of parts and waste materials. A secondary objective is to increase the fundamental understanding of photocatalytic chemistry. Cleaning and extraction using supercritical carbon dioxide (scCO2) can be applied to the solution of a wide range of environmental and pollution prevention problems in the DOE complex. Work is being done that explores scCO2 in applications ranging from cleaning contaminated soil to cleaning components constructed from plutonium. The rationale for use of scCO2 are based on the benign nature, availability and low cost, attractive solvent properties, and energy efficient separation of the extracted solute from the solvent by moderate temperature or pressure changes. To date, R and D has focussed on the methods and applications of the extraction steps of the process. Little has been done that addresses methods to polish the scCO2 for recycle in the cleaning or extraction operations. In many applications it will be desirable to reduce the level of contamination from that which would occur at steady state operation of a process. This proposal addresses chemistry to achieve that. This would be an alternative to removing a fraction of the contaminated scCO2 for disposal and using makeup scCO2. A

  12. Efficient utilization of pentoses for bioproduction of the renewable two-carbon compounds ethylene glycol and glycolate.

    Science.gov (United States)

    Pereira, Brian; Li, Zheng-Jun; De Mey, Marjan; Lim, Chin Giaw; Zhang, Haoran; Hoeltgen, Claude; Stephanopoulos, Gregory

    2016-03-01

    The development of lignocellulose as a sustainable resource for the production of fuels and chemicals will rely on technology capable of converting the raw materials into useful compounds; some such transformations can be achieved by biological processes employing engineered microorganisms. Towards the goal of valorizing the hemicellulose fraction of lignocellulose, we designed and validated a set of pathways that enable efficient utilization of pentoses for the biosynthesis of notable two-carbon products. These pathways were incorporated into Escherichia coli, and engineered strains produced ethylene glycol from various pentoses, including simultaneously from D-xylose and L-arabinose; one strain achieved the greatest reported titer of ethylene glycol, 40g/L, from D-xylose at a yield of 0.35g/g. The strategy was then extended to another compound, glycolate. Using D-xylose as the substrate, an engineered strain produced 40g/L glycolate at a yield of 0.63g/g, which is the greatest reported yield to date. PMID:26711083

  13. Extraction of semivolatile organic compounds from high-efficiency particulate air (HEPA) filters by supercritical carbon dioxide

    International Nuclear Information System (INIS)

    Supercritical fluid extraction (SFE) using unmodified carbon dioxide has been explored as an alternative method for the extraction of semivolatile organic compounds from high-efficiency particulate air (HEPA) filters. HEPA filters provide the final stage of containment on many exhaust systems in US Department of Energy (DOE) facilities by preventing the escape of chemical and radioactive materials entrained in the exhausted air. The efficiency of the filters is tested by the manufacturer and DOE using dioctylphthalate (DOP), a substance regulated by the US Environmental Protection Agency under the Resource Conservation and Recovery Act. Therefore, the filters must be analyzed for semivolatile organics before disposal. Ninety-eight acid, base, and neutral semivolatile organics were spiked onto blank HEPA material and extracted using SFE, Soxhlet, automated Soxhlet, and sonication techniques. The SFE conditions were optimized using a Dionex SFE-703 instrument. Average recoveries for the 98 semivolatile compounds are 82.7% for Soxhlet, 74.0% for sonication, 70.2% for SFE, and 62.9% for Soxtec. Supercritical fluid extraction reduces the extraction solvent volume to 10--15 mL, a factor of 20--30 less than Soxhlet and more than 5 times less than Soxtec and sonication. Extraction times of 30--45 min are used compared to 16--18 h for Soxhlet extraction

  14. Compound-specific carbon and hydrogen isotope analysis of sub-parts per billion level waterborne petroleum hydrocarbons

    Science.gov (United States)

    Wang, Y.; Huang, Y.; Huckins, J.N.; Petty, J.D.

    2004-01-01

    Compound-specific carbon and hydrogen isotope analysis (CSCIA and CSHIA) has been increasingly used to study the source, transport, and bioremediation of organic contaminants such as petroleum hydrocarbons. In natural aquatic systems, dissolved contaminants represent the bioavailable fraction that generally is of the greatest toxicological significance. However, determining the isotopic ratios of waterborne hydrophobic contaminants in natural waters is very challenging because of their extremely low concentrations (often at sub-parts ber billion, or even lower). To acquire sufficient quantities of polycyclic aromatic hydrocarbons with 10 ng/L concentration for CSHIA, more than 1000 L of water must be extracted. Conventional liquid/liquid or solid-phase extraction is not suitable for such large volume extractions. We have developed a new approach that is capable of efficiently sampling sub-parts per billion level waterborne petroleum hydrocarbons for CSIA. We use semipermeable membrane devices (SPMDs) to accumulate hydrophobic contaminants from polluted waters and then recover the compounds in the laboratory for CSIA. In this study, we demonstrate, under a variety of experimental conditions (different concentrations, temperatures, and turbulence levels), that SPMD-associated processes do not induce C and H isotopic fractionations. The applicability of SPMD-CSIA technology to natural systems is further demonstrated by determining the ??13C and ??D values of petroleum hydrocarbons present in the Pawtuxet River, RI. Our results show that the combined SPMD-CSIA is an effective tool to investigate the source and fate of hydrophobic contaminants in the aquatic environments.

  15. Extraction of semivolatile organic compounds from high-efficiency particulate air (HEPA) filters by supercritical carbon dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Schilling, J.B.

    1997-09-01

    Supercritical fluid extraction (SFE) using unmodified carbon dioxide has been explored as an alternative method for the extraction of semivolatile organic compounds from high-efficiency particulate air (HEPA) filters. HEPA filters provide the final stage of containment on many exhaust systems in US Department of Energy (DOE) facilities by preventing the escape of chemical and radioactive materials entrained in the exhausted air. The efficiency of the filters is tested by the manufacturer and DOE using dioctylphthalate (DOP), a substance regulated by the US Environmental Protection Agency under the Resource Conservation and Recovery Act. Therefore, the filters must be analyzed for semivolatile organics before disposal. Ninety-eight acid, base, and neutral semivolatile organics were spiked onto blank HEPA material and extracted using SFE, Soxhlet, automated Soxhlet, and sonication techniques. The SFE conditions were optimized using a Dionex SFE-703 instrument. Average recoveries for the 98 semivolatile compounds are 82.7% for Soxhlet, 74.0% for sonication, 70.2% for SFE, and 62.9% for Soxtec. Supercritical fluid extraction reduces the extraction solvent volume to 10--15 mL, a factor of 20--30 less than Soxhlet and more than 5 times less than Soxtec and sonication. Extraction times of 30--45 min are used compared to 16--18 h for Soxhlet extraction.

  16. Carbon-14 labelled sucrose transportation in an Arabidopsis thaliana using an imaging plate and real time imaging system

    International Nuclear Information System (INIS)

    As an approach to increased production of rape seed oil from Brassica napus L., Arabidopsis thaliana, a species from the same Brassicaceae family, was used to investigate transport behavior and distribution of matter in the plant body. In this study, sucrose, an initial metabolic product of photosynthesis, labeled with carbon-14 was used. The sucrose was applied to A. thaliana via the surface of a rosette leaf. Using the real time radioisotope imaging system we developed and an imaging plate (IP), images of whole or part of the sample were obtained. The sucrose assimilation products were accumulated in maturing tissue such as flowers and fruits, and in a joint part. From the comparison among branches and stems, it was indicated that there were different patterns of demand and distribution of sucrose assimilation products depending on the tissue and its growing stage. This might be caused by either morphological reason such as diameter and location of the sieve tube, or genetic factors such as an activity of a membrane transport protein. Because of self-absorption of carpels, it was difficult to observe the accumulation of carbon-14 in the seeds inside the fruits; however, an IP image of a frozen section of a fruit revealed that carbon-14 transport to seeds was higher than that of carpels. These methods will help us gain insight into matter transport and strategies to improve the production of rape seed oil. (author)

  17. MODIFIED SCREEN-PRINTED CARBON ELECTRODES WITH TYROSINASE FOR DETERMINATION OF PHENOLIC COMPOUNDS IN SMOKED FOOD

    Directory of Open Access Journals (Sweden)

    V. Dragancea

    2010-12-01

    Full Text Available A screen-printed carbon electrode modified with tyrosinase (SPCE-Tyr/Paa/Glut has been developed for the determination of phenol concentration in real samples. The resulting SPCE-Tyr/Paa/Glut was prepared in a one-step procedure, and was then optimized as an amperometric biosensor operating at 0 mV versus Ag/AgCl for phenol determination in flow injection mode. Phenol detection was realized by electrochemical reduction of quinone produced by tyrosinase activity. The possibility of using the developed biosensor to determine phenol concentrations in various smoked products (bacon, ham, chicken and salmon was also evaluated. Gas chromatography (GC method was used for result validation obtained in flow injection mode using amperometric biosensor. The result showed good correlation with those obtained by flowinjection analysis (FIA.

  18. Uranium value leaching with ammonium carbonate and/or bicarbonate plus nitrate oxidant and optionally oxidation-catalytic metal compounds

    International Nuclear Information System (INIS)

    In accordance with the present invention, uranium values are extracted from solid materials containing uranium in lower valence states than its hexavalent state comprising contacting the solid materials containing uranium with an alkaline leach solution containing the ionic species NH4+ and NO3- in an amount sufficient to convert at least a portion of the uranium in valence states lower than its hexavalent state to its hexavalent state. In another embodiment of the present invention, the aqueous alkaline leach solution is an aqueous solution of a carbonate selected from the group consisting of ammonium carbonate, ammonium bicarbonate and mixtures thereof. In a further embodiment, ionic species NO3- is supplied by an alkaline nitrate. In yet another embodiment of the present invention, the aqueous alkaline leach solution additionally contains at least one catalytic compound of a metal selected from the group consisting of copper, cobalt, iron, nickel, chromium and mixtures thereof adapted to assure the pesence of the ionic species Cu++, Co++, Fe+++, Ni++, Cr+++ and mixtures thereof, respectively, is present during the contacting of the solid materials containing uranium with the aqueous alkaline leach solution in an amount sufficient to catalyze the oxidation of at least a part of the uranium in valence states lower than its hexavalent state to its hexavalent state

  19. Adsorption onto Activated Carbon Fiber Cloth and Electrothermal Desorption of Volatile Organic Compound (VOCs): A Specific Review

    Institute of Scientific and Technical Information of China (English)

    Pierre Le Cloirec

    2012-01-01

    A general research program, focusing on activated carbon fiber cloths (ACFC) and felt for environmental protection was performed. The objectives were multiple: (i) a better understanding of the adsorption mecha- nisms of these kinds of materials; (ii) the specification and optimization of new processes using these adsorbents; (iii) the modeling of the adsorption of organic pollutants using both the usual and original approaches; (iv) applications of ACFC in industrial processes. The general question was: how can activated carbon fiber cloths and felts be used in air treatment processes for the protection of environment. In order to provide an answer, different approaches were adopted. The materials (ACFC) were characterized in terms of macro structure and internal porosity. Specific studies were performed to get the air flow pattern through the fabrics. Head loss data were generated and modeled as a fi.mction of air velocity. The performances of ACF to remove volatile organic compounds (VOCs) were approached with the adsorption isotherms and breakthrough curves in various operating conditions. Regenera- tion by Joule effect shows a homogenous heating of adsorber modules with rolled or pleated layers. Examples of industrial developments were presented showing an interesting technology for the removal of VOCs, such as dichloromethane, benzene, isopropyl alcohol and toluene, alone or in a complex mixture.

  20. In situ sorption of hydrophobic organic compounds to sediment amended with activated carbon

    International Nuclear Information System (INIS)

    Contaminated sediments can be remediated by adding carbonaceous materials (CM), e.g. activated carbons (AC). Here, we analyze published datasets from AC amendment trials to identify variation in the effectiveness of AC in reducing porewater concentrations of hydrophobic organic contaminants (HOCs). The analysis uses a model that separates the contribution of HOC sorption to AC by parameterzing the sorption contributions by amorphous organic matter and black carbon (BC). It appears that sorption to BC increased with LogKOW, whereas sorption to AC showed a relatively narrow range of affinity properties with a median Freundlich LogKF,AC value of 7.2 (μg/kgAC)/(μg/L)n (IQR = 7.0–7.5) for polychlorinated biphenyls (PCBs) and 8.6 (IQR = 8.3–8.8) for polycyclic aromatic hydrocarbons (PAHs). Estimated Freundlich exponents were nF,AC = 0.74 for PCBs and 0.82 for PAH. Sorption to AC was stronger than to BC for chemicals below LogKOW = 6.3–6.6. For HOC risk reduction this is favorable, because chemicals with low KOW show generally higher bioavailable concentrations. - Highlights: ► We provide a conceptual framework to assess affinity constants for HOC sorption to CM. ► We determined the affinity parameters for HOC sorption to BC and AC. ► HOC sorption to AC showed a narrow range of AC affinity properties. ► HOC sorption to AC was stronger than to BC for chemicals below LogKOW = 6.3–6.6. ► 1% of AC appears to be sufficient to reduce pore water concentration by 99%. - We analyzed datasets from AC amendment trials to identify the variation in AC effectiveness and to explore to what extent HOC binding to AC may be generalized.

  1. Determination of Carbon-14 (14C) and Tritium (3H) in the graphite thermal column of a IRT-2000 research reactor in Sofia

    International Nuclear Information System (INIS)

    Radiocarbon has average, and tritium has low level of radiotoxicity, but both are easily absorbable radionuclide from the body as due to their chemical nature they are included in almost all the chemical compounds involved in metabolic chains and in structure of proteins and biological macromolecules. Due to above mentioned reasons, the analysis and determination of these two major radionuclides is very significant for radiation protection for both the public and the environment as well as for occupational exposure of personnel. This publication describes the detailed procedure for determining the concentration of 3H and 14C in samples selected at the stage 'partial dismantling' of the research nuclear reactor IRT-2000 reconstruction. The procedure consists graphite sample thermal burning in the tubing muffle furnace at a maximum temperature of 850'0C. After combustion the gas mixture passes through a CuO catalyst, heated to 450-5000C and through a series of traps for 3H and 14C capturing. The captured CO2+ 14CO2 as Na2CO3 in NaOH precipitates with BaCl2 as BaCO3 and it is followed by a liquid scintillation spectrometry measurements

  2. Compound-Specific Carbon and Hydrogen Isotope Analysis - Field Evidence of MTBE Bioremediation

    Science.gov (United States)

    Kuder, T.; Kolhatkar, R. V.; Philp, P.; Wilson, J. T.; Landmeyer, J. E.; Allen, J.

    2002-12-01

    Compound-specific stable isotope analysis allows opportunity to determine the isotopic ratios of individual contaminants. The technique has been applied to confirm biodegradation in studies of chlorinated solvents and recently BTEX, MTBE and TBA. Chemical reactions (including bio- and inorganic degradation) tend to favor molecules with the lighter isotopic species (e.g., 12C, 1H), resulting with enrichment of the unreacted substrate in the heavier isotopic species (13C, D), referred to as kinetic isotopic fractionation, so that the extent of fractionation may be used as a proxy for biodegradation. Processes such as volatilization, sorption etc., result in minimal degree of fractionation and do not interfere with the isotopic signal due to biodegradation. The results presented here show the first successful applications of compound-specific isotope analysis to understanding MTBE biodegradation in the field, at both aerobic and anaerobic sites. Observed fractionations suggest that two different biodegradation pathways may be involved. At a number of anaerobic locations major fractionation effects were observed for both C and H; enrichment factors Ÿnfor both elements were approaching or exceeding -10. A laboratory microcosm study using an enrichment culture yielded similar results (C data only). A characteristic feature of these sites was the presence of high concentrations of TBA. Conversely, at a number of sites, the C composition remained stable with little fractionation and stayed within the analytical precision range or changed minimally, while H displayed significant fractionation in excess of 60 per mil. Moderate agreement of the data with Rayleigh fractionation model was observed, suggesting that biodegradation effect was distorted by variability at the source or the plume was not homogeneous. The enrichment factor calculated for these data is similar to the one Ÿnpublished for aerobic microcosm of MTBE-degrading culture from Vandenberg AFB by Gray et al

  3. Simulation of Carbon-14 Migration Through a Thick Unsaturated Alluvial Basin Resulting from an Underground Nuclear Explosion

    Science.gov (United States)

    Martian, P.; Larentzos, J.

    2008-12-01

    Yucca Flat is one of several areas on the Nevada Test Site that was used for underground nuclear testing. Extensive testing performed in the unsaturated and saturated zones have resulted in groundwater contamination and surface subsidence craters in the vicinity of the underground test areas. Simulation of multiphase 14C transport through the thick Yucca Flat alluvial basin was performed to estimate the magnitude of radionuclide attenuation occurring within the unsaturated zone. Parameterization of the 14C transport in the multiphase flow and transport simulator (FEHM) was verified with experimental data collected from a large unsaturated soil column experiment. The experimental data included 14C as a radio-labeled bicarbonate solution, SF6 gas, and lithium bromide solution breakthroughs. Two representative simulation cases with working points located at shallow and deep depths relative to the water table were created to investigate the impact of subsidence crater-enhanced recharge, crater-playa areal extent, gas-phase partitioning, solid-phase partitioning, and a reduced permeability/porosity compressed zone created during the explosion on 14C transport. The representative shallow test had a detonation point located 175 m below land surface, and the deep test had a working point 435 m below land surface in a 500 m deep unsaturated zone. Carbon-14 transport is influenced by gas-phase diffusion and sorption within the alluvium. Gas-phase diffusion is an attenuation mechanism that transports 14C gas as 14CO2 throughout the unsaturated zone and exposes it to a large amount of soil moisture, resulting in dilute concentrations. The simulations indicated that the majority of the 14C inventory remains in the unsaturated zone over a 1,000-year time period after detonation because gas-phase diffusion moves the bulk of the 14C away from the higher recharge occurring in crater playas. Retardation also plays a role in slowing advective aqueous phase transport to the water

  4. Sup(14)C activity of dissolved organic carbon fractions in the north-central Pacific and Sargasso Sea

    International Nuclear Information System (INIS)

    Radiocarbon measurements of dissolved organic carbon (DOC) oxidizable by ultraviolet irradiation (DOCuv) yielded apparent ages of ∼6,000 yr in the deep waters of the oligotrophic north-central Pacific gyre. Recent reports of a potentially larger pool of DOC as measured by high-temperature catalytic combustion (DOChtc) using discrete injections of sea water have led to speculation that 'younger', more recently produced DOC could contribute significantly to overall oceanic organic carbon fluxes, owing to its suspected greater biological lability. Here we present a comparison of Δ14C (the deviation in parts per thousand from the 14C activity of nineteenth-century wood) of the DOChtc, DOCuv and humic substances in profiles from the oligotrophic north-central Pacific and Sargasso Sea. For each ocean, the Δ14C values of all three fractions are remarkably similar, yielding no evidence for a component of DOC that is cycled through the system on timescales shorter than several thousands of years. We observe an age difference between the two oceans of ∼2,000 yr for the deepest DOC, which can largely be accounted for by differences in the Δ14C of the DOC sources to the deep basins, and by the different deep-water circulation patterns and transit times in the two oceans. (author)

  5. Analysis of preference for carbon source utilization among three strains of aromatic compounds degrading Pseudomonas.

    Science.gov (United States)

    Karishma, M; Trivedi, Vikas D; Choudhary, Alpa; Mhatre, Akanksha; Kambli, Pranita; Desai, Jinal; Phale, Prashant S

    2015-10-01

    Soil isolates Pseudomonas putida CSV86, Pseudomonas aeruginosa PP4 and Pseudomonas sp. C5pp degrade naphthalene, phthalate isomers and carbaryl, respectively. Strain CSV86 displayed a diauxic growth pattern on phenylpropanoid compounds (veratraldehyde, ferulic acid, vanillin or vanillic acid) plus glucose with a distinct second lag-phase. The glucose concentration in the medium remained constant with higher cell respiration rates on aromatics and maximum protocatechuate 3,4-dioxygenase activity in the first log-phase, which gradually decreased in the second log-phase with concomitant depletion of the glucose. In strains PP4 and C5pp, growth profile and metabolic studies suggest that glucose is utilized in the first log-phase with the repression of utilization of aromatics (phthalate or carbaryl). All three strains utilize benzoate via the catechol 'ortho' ring-cleavage pathway. On benzoate plus glucose, strain CSV86 showed preference for benzoate over glucose in contrast to strains PP4 and C5pp. Additionally, organic acids like succinate were preferred over aromatics in strains PP4 and C5pp, whereas strain CSV86 co-metabolizes them. Preferential utilization of aromatics over glucose and co-metabolism of organic acids and aromatics are found to be unique properties of P. putida CSV86 as compared with strains PP4 and C5pp and this property of strain CSV86 can be exploited for effective bioremediation. PMID:26316546

  6. A survey of methods to immobilize tritium and carbon-14 arising from a nuclear fuel reprocessing plant

    International Nuclear Information System (INIS)

    This report reviews the literature on methods to separate and immobilize tritium (3H) and carbon-14 (14C) released from U02 fuel in a nuclear fuel reprocessing plant. It was prepared as part of a broader review of fuel reprocessing waste management methods that might find future application in Canada. The calculated inventories of both 3H and 14C in used fuel are low; special measures to limit releases of these radionuclides from reprocessing plants are not currently in place, and may not be necessary in future. If required, however, several possible approaches to the concentration and immobilization of both radionuclides are available for development. Technology to control these radionuclides in reactor process streams is in general more highly developed than for reprocessing plant effluent, and some control methods may be adaptable to reprocessing applications

  7. Theoretical investigation of a novel high density cage compound 4,8,11,14,15-pentanitro-2,6,9,13-tetraoxa-4,8,11,14,15-pentaazaheptacyclo[5.5.1.1(3,11).1(5,9)] pentadecane.

    Science.gov (United States)

    Lin, He; Zhu, Shun-guan; Zhang, Lin; Peng, Xin-hua; Chen, Peng-yuan; Li, Hong-zhen

    2013-03-01

    A novel polynitro cage compound 4,8,11,14,15-pentanitro-2,6,9,13-tetraoxa-4,8,11,14,15-pentaazaheptacyclo [5.5.1.1(3,11).1(5,9)]pentadecane(PNTOPAHP) has been designed and investigated at the DFT-B3LYP/6-31(d) level. Properties, such as electronic structure, IR spectrum, heat of formation, thermodynamic properties and crystal structure have been predicted. This compound is most likely to crystallize in C2/c space group, and the corresponding cell parameters are Z = 8, a = 29.78 Å, b = 6.42 Å, c = 32.69 Å, α = 90.00°, β = 151.05°, γ = 90.00° and ρ = 1.94 g/cm(3). In addition, the detonation velocity and pressure have also been calculated by the empirical Kamlet-Jacobs equation. As a result, the detonation velocity and pressure of this compound are 9.82 km/s, 44.67 GPa, respectively, a little higher than those of 4,10-dinitro-2,6,8,12-tetraoxa-4,10-diazaisowurtzitane(TEX, 9.28 km/s, 40.72 GPa). This compound has a comparable chemical stability to TEX, based on the N-NO(2) trigger bond length analysis. The bond dissociation energy ranges from 153.09 kJ mol(-1) to 186.04 kJ mol(-1), which indicates that this compound meets the thermal stability requirement as an exploitable HEDM. PMID:23111684

  8. Use of carbon-14 for the study of elementary carbon exchange between methane and its chemisorption residues on metallic films

    International Nuclear Information System (INIS)

    After giving the results of the most recent work done with a view to providing a rational account of the exchanges between two gases in contact with a catalyst, the authors, using C14, proceed to study elementary exchange between methane and its chemisorption residues on molybdenum films. The surface is labelled in two ways: by chemisorption of C14H4 at different temperatures; or by exchange between C14H4 with a high specific activity and a metallic film previously treated with inactive methane. The C14 is counted in the form of CO2 in the Geiger region. The results show that the exchange rate is measurable from about 100o C onwards and that it reaches a maximum at about 250o C. Furthermore, the exchange is governed by laws which vary according to the prior treatment of the surface. On the basis of the results discussed, the authors suggest a methane displacement pattern which they compare with the CH4 and D2 exchange mechanisms suggested by Kemball. (author)

  9. Characterization of carbon-14 generated by the nuclear power industry. Final report

    International Nuclear Information System (INIS)

    This report describes an evaluation of C-14 production rates in light-water reactors (LWRs) and characterization of its chemical speciation and environmental behavior. The study estimated the total production rate of the nuclide in operating PWRs and BWRs along with the assessment of the C-14 content of solid radwaste. The major source of production of C-14 in both PWR's and BWRs was the activation of 0-17 in the water molecule and of N-14 dissolved in reactor coolant. The production of C-14 was estimated to range from 7 Ci/GW(e)-year to 11 Ci/GW(e)-year. The estimated range of the quantity of C-14 in LLW was 1-2 Ci/ reactor-year which compares favorably with data obtained from shipping manifests. The environmental behavior of C-14 associated with low-level waste (LLW) disposal is greatly dependent upon its chemical speciation. This scoping study was performed to help identify the occurrence of inorganic and organic forms of C-14 in reactor coolant water and in primary coolant demineralization resins. These represent the major source for C-14 in LLW from nuclear power stations. Also, the behavior of inorganic and two of the organic forms of C-14 on soil uptake was determined by measuring distribution coefficients (Kd's) on two soil types and a cement, using two different groundwater types. This study confirms that C-14 concentrations are significantly higher in the primary coolant from PWR stations compared to BWR stations. The C-14 followed trends of Co-60 generation during primary coolant demineralization at all but one of the stations examined. However, the C-14/Co-60 activity ratios measured by this study in resin samples through which samples of coolant were drawn were about 8 to 42 times higher than those reported for waste samples in the industry data base for PWR stations, and 15 to 730 times lower for the BWR stations

  10. Adsorption of odorous sulfur compounds onto activated carbons modified by gamma irradiation.

    Science.gov (United States)

    Vega, Esther; Sánchez-Polo, Manuel; Gonzalez-Olmos, Rafael; Martin, María J

    2015-11-01

    A commercial activated carbon (AC) was modified by gamma irradiation and was tested as adsorbent for the removal of ethyl mercaptan, dimethyl disulfide and dimethyl disulfide in wet conditions. Modifications were carried out under five different conditions: irradiation in absence of water, in presence of ultrapure water, in ultrapure water at pH=1.0 and 1000 mg L(-1) Cl(-), in ultrapure water at pH=7.5 and 1000 mg L(-1) Br(-), and in ultrapure water at pH=12.5 and 1000 mg L(-1) NO3(-). The chemical properties of each AC were characterized by elemental analysis, temperature programmed desorption and X-ray photoelectron spectroscopy. Outcomes show that a large number of oxygen functional groups were incorporated in the AC surface by gamma irradiation, especially in the AC irradiated in the presence of ultrapure water. The dynamic adsorption test results reveal that the incorporation of oxygen functional groups did not enhance the adsorption capacities for dimethyl sulfide and dimethyl disulfide. A significant improvement in the ethyl mercaptan adsorption capacity was correlated with the incorporation of phenolic groups in the AC surface. Moreover, diethyl disulfide was detected as by-product of ethyl mercaptan oxidation process under wet conditions and its formation depended on the chemical properties of ACs. PMID:26160734

  11. Hydrogen and carbon isotopic ratios of polycyclic aromatic compounds in two CM2 carbonaceous chondrites and implications for prebiotic organic synthesis

    Science.gov (United States)

    Huang, Yongsong; Aponte, José C.; Zhao, Jiaju; Tarozo, Rafael; Hallmann, Christian

    2015-09-01

    Study of meteoritic organic compounds offers a unique opportunity to understand the origins of the organic matter in the early Solar System. Meteoritic polycyclic aromatic hydrocarbons (PAHs) and heteropolycyclic aromatic compounds (HACs) have been studied for over fifty years, however; their hydrogen stable isotopic ratios (δD) have never been reported. Compound-specific δD measurements of PAHs and HACs are important, in part because the carbon isotopic ratios (δ13C) of various meteoritic PAHs cannot be readily distinguished from their terrestrial counterparts and it is difficult to rule out terrestrial contamination based on carbon isotopic ratios alone. In this study, we have extracted and identified more than sixty PAHs and HACs present in two CM2 carbonaceous chondrites Murchison and LON 94101. Their carbon and hydrogen stable isotopic ratios (δ13C and δD) were measured and used to discuss about their synthetic environments and formation mechanisms. The concentration of aromatic compounds is ∼30% higher in Murchison than in the Antarctic meteorite LON 94101, but both samples contained similar suites of PAHs and HACs. All PAHs and HACs found exhibited positive δD values (up to 1100‰) consistent with an extraterrestrial origin, indicating the relatively low δ13C values are indeed an inherent feature of the meteoritic aromatic compounds. The hydrogen isotopic data suggest aromatic compounds in carbonaceous chondrites were mainly formed in the cold interstellar environments. Molecular level variations in hydrogen and carbon isotopic values offer new insights to the formation pathways for the aromatic compounds in carbonaceous chondrites.

  12. Oxygène-18, carbone-13, carbone-14 et diatomées dans les quatre carottes du lac Huynamarca (Bolivie) : premiers résultats

    OpenAIRE

    Wirrmann, Denis; Servant Vildary, Simone; Fontes, J.C.

    1982-01-01

    L'étude de géochimie isotopique des carbonates coquilliers de quatre carottes du lac Huynamarca (Bolivie), ainsi que les datations au carbone-14 de quelques échantillons montrent qu'au cours des dix derniers millénaires le bilan hydrologique du lac Titicaca a considérablement varié. Une phase sèche, située entre 3650 et 5325 ans B.P. se traduit par une baisse du niveau du lac d'au moins dix mètres par rapport à l'actuel, avec comme corrolaire l'augmentation de la teneur en sels dissous dans l...

  13. Determination of solubility product of lead carbonate using 14C radionuclide

    International Nuclear Information System (INIS)

    Using the obtained experimental data on lead carbonate solubility in bidistilled water at 25 deg C, the value of lead carbonate solubility product, which constituted (3.6+-0.1)x10sup(-11) at confidence level 0.95, is determined. The use of radioactive indicators permitted to eliminate the negative effect of carbonate-ion excess concentration and pH and to specify similar literature data. A high stability of leadcarbonate supersaturated solutions is shown, which can be explained by a slow rate of the process PbCO3 (aq) → PbCO3 (cr)

  14. Developing microbe-plant interactions for applications in plant-growth promotion and disease control, production of useful compounds, remediation, and carbon sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Wu, C.H.; Bernard, S.; Andersen, G.L.; Chen, W.

    2009-03-01

    Interactions between plants and microbes are an integral part of our terrestrial ecosystem. Microbe-plant interactions are being applied in many areas. In this review, we present recent reports of applications in the areas of plant-growth promotion, biocontrol, bioactive compound and biomaterial production, remediation and carbon sequestration. Challenges, limitations and future outlook for each field are discussed.

  15. Determination of solubility product of lead carbonate, using 14C radionuclide

    International Nuclear Information System (INIS)

    On the basis of experimental data on the solubility of lead carbonate in double distilled water at 25 C, the solubility product of lead carbonate has been found to be (3.6 + or - 0.1) .10-11 with a 0.95 confidence probability. Use of radioactive indicators in these experiments made it possible to eliminate the adverse effects from excess concentration of carbonate ions and from pH, and to refine the analogous literature data. It has been shown that supersaturated solutions of lead carbonate are highly stable; this can be explained by the slow course of the process PbCO3 (ag)→ PbCO3 (cr)

  16. Design, synthesis and nonlinear optical properties of (E)-1-(4-substituted)-3-(4-hydroxy-3-nitrophenyl) prop-2-en-1-one compounds

    Science.gov (United States)

    Saha, Amrita; Shukla, Vijay; Choudhury, Sudip; Jayabalan, J.

    2016-06-01

    A new series of (E)-1-(4-substituted)-3-(4-hydroxy-3-nitrophenyl) prop-2-en-1-one compounds have been synthesized by Claisen-Schmidt condensation reaction. Nonlinear optical characterization were carried out using z-scan technique with nanosecond pulses. These samples are found to exhibit strong nonlinear absorption at 532 nm and the nonlinear absorption coefficient of these samples exponentially increases with the increase of phonon characteristic energy. This relation speaks the role of phonon in the origin of nonlinear absorption in these compounds. The reported dependence of optical nonlinearity of the chalcone derivatives on the phonon characteristic energy will help in designing similar class of new molecules with high nonlinear coefficients.

  17. Some interesting and exotic applications of carbon-14 dating by accelerator mass spectrometry

    International Nuclear Information System (INIS)

    There are many applications of 14C dating and other measurements using accelerator mass spectrometry (AMS). In particular, applications to dating of archaeological samples and interesting artifacts are discussed. Other applications, such as to extraterrestrial materials such as lunar samples and meteorites show the broad range of topics that can be addressed with 14C studies.

  18. Differentiation of Pigment in Eggs Using Carbon ((13)C/(12)C) and Nitrogen ((15)N/(14)N) Stable Isotopes.

    Science.gov (United States)

    Sun, Feng M; Shi, Guang Y; Wang, Hui W

    2016-07-01

    Consumers prefer natural and healthy food, but artificial pigments are often abused in egg products. The study aimed at differentiating the origin of pigments in eggs by applying the technique of carbon ((13)C/(12)C) and nitrogen ((15)N/(14)N) stable isotope analysis. Five hundred sixty laying hens were randomly distributed into 14 treatments, which were divided into four groups: maize, carophyll red pigment, carophyll yellow pigment, and a mixture of carophyll red and yellow pigments. Eggs were collected and pretreated to determe the values of the Roche Yolk Color Fan (RCF), δ(13)C, and δ(15)N. With increasing maize content, the RCF and δ(13)C values of yolks increased. Moreover, the RCF values in the three pigment groups were significantly influenced by the artificial colors, but δ(13)C values were not significantly different, regardless of the existence of pigment. The δ(15)N values in all treatments did not vary as regularly as the carbon stable isotope. A strong positive correlation was found between RCF and δ(13)C in the maize group, but no such correlation was be observed in the pigment groups. It is concluded that carbon stable isotope ratio analysis (δ(13)C) of the yolk can be used to differentiate the origin of the pigment added to eggs. PMID:27302905

  19. Quantification of Helicobacter pylori infection in gastritis and ulcer disease using a simple and rapid carbon-14-urea breath test

    Energy Technology Data Exchange (ETDEWEB)

    Debongnie, J.C.; Pauwels, S.; Raat, A.; de Meeus, Y.; Haot, J.; Mainguet, P. (Department of Nuclear Medicine, University of Louvain Medical School, Brussels (Belgium))

    1991-06-01

    Gastric urease was studied isotopically in 230 patients with biopsy-proven normal mucosa or chronic gastritis, including 59 patients with ulcer disease. Carbon-14-urea was given in 25 ml of water without substrate carrier or nutrient-dense meal, and breath samples were collected over a 60-min period. The amount of 14CO2 excreted at 10 min was independent of the rate of gastric emptying and was not quantitatively influenced by the buccal urease activity. The 10-min 14CO2 values discriminated well between Helicobacter pylori positive and negative patients (94% sensitivity, 89% specificity) and correlated with the number of organisms assessed by histology. The test was a good predictor of chronic gastritis (95% sensitivity and 96% specificity), and a quantitative relationship was observed between 14CO2 values and the severity and activity of the gastritis. In H. pylori positive patients, breath 14CO2 was found to be similar in patients with and without ulcer disease, suggesting that the number of bacteria is not a determining factor for the onset of ulceration.

  20. Quantification of Helicobacter pylori infection in gastritis and ulcer disease using a simple and rapid carbon-14-urea breath test

    International Nuclear Information System (INIS)

    Gastric urease was studied isotopically in 230 patients with biopsy-proven normal mucosa or chronic gastritis, including 59 patients with ulcer disease. Carbon-14-urea was given in 25 ml of water without substrate carrier or nutrient-dense meal, and breath samples were collected over a 60-min period. The amount of 14CO2 excreted at 10 min was independent of the rate of gastric emptying and was not quantitatively influenced by the buccal urease activity. The 10-min 14CO2 values discriminated well between Helicobacter pylori positive and negative patients (94% sensitivity, 89% specificity) and correlated with the number of organisms assessed by histology. The test was a good predictor of chronic gastritis (95% sensitivity and 96% specificity), and a quantitative relationship was observed between 14CO2 values and the severity and activity of the gastritis. In H. pylori positive patients, breath 14CO2 was found to be similar in patients with and without ulcer disease, suggesting that the number of bacteria is not a determining factor for the onset of ulceration

  1. Preliminary study of the impact of tritium and carbon 14 releases from the Saint-Alban nuclear power plant. CRIIRAD N.04-20 V1 Report

    International Nuclear Information System (INIS)

    After having recalled the results of previous studies on the radioactivity in surface water and land environments, and outlined the need of an investigation of the tritium and carbon 14 contamination, this report defines the objectives of this investigation, the adopted methodology (choice of plants, tritium and carbon 14 dose measurements, and sampling to study time variations). It recalls some aspects of tritium and carbon 14 releases (production of radionuclides, origins of emissions in the environment, assessments by EDF). It reports the investigation and the assessment of tritium activity in a land environment and in rain waters about the investigated site, and the investigation and the assessment of carbon 14 activity within the same environment. It reports preliminary results concerning the aquatic environment

  2. Selectivity of Chemoresistive Sensors Made of Chemically Functionalized Carbon Nanotube Random Networks for Volatile Organic Compounds (VOC

    Directory of Open Access Journals (Sweden)

    Jean-François Feller

    2014-01-01

    Full Text Available Different grades of chemically functionalized carbon nanotubes (CNT have been processed by spraying layer-by-layer (sLbL to obtain an array of chemoresistive transducers for volatile organic compound (VOC detection. The sLbL process led to random networks of CNT less conductive, but more sensitive to vapors than filtration under vacuum (bucky papers. Shorter CNT were also found to be more sensitive due to the less entangled and more easily disconnectable conducting networks they are making. Chemical functionalization of the CNT’ surface is changing their selectivity towards VOC, which makes it possible to easily discriminate methanol, chloroform and tetrahydrofuran (THF from toluene vapors after the assembly of CNT transducers into an array to make an e-nose. Interestingly, the amplitude of the CNT transducers’ responses can be enhanced by a factor of five (methanol to 100 (chloroform by dispersing them into a polymer matrix, such as poly(styrene (PS, poly(carbonate (PC or poly(methyl methacrylate (PMMA. COOH functionalization of CNT was found to penalize their dispersion in polymers and to decrease the sensors’ sensitivity. The resulting conductive polymer nanocomposites (CPCs not only allow for a more easy tuning of the sensors’ selectivity by changing the chemical nature of the matrix, but they also allow them to adjust their sensitivity by changing the average gap between CNT (acting on quantum tunneling in the CNT network. Quantum resistive sensors (QRSs appear promising for environmental monitoring and anticipated disease diagnostics that are both based on VOC analysis.

  3. Spatial analysis of Carbon-14 dynamics in a wetland ecosystem (Duke Swamp, Chalk River Laboratories, Canada)

    International Nuclear Information System (INIS)

    A detailed survey was conducted to quantify the spatial distribution of 14C in Sphagnum moss and underlying soil collected in Duke Swamp. This wetland environment receives 14C via groundwater pathways from a historic radioactive Waste Management Area (WMA) on Atomic Energy Canada Limited (AECL)'s Chalk River Laboratories (CRL) site. Trends in 14C specific activities were evaluated with distance from the sampling location with the maximum 14C specific activity (DSS-35), which was situated adjacent to the WMA and close to an area of groundwater discharge. Based on a spatial evaluation of the data, an east-to-west 14C gradient was found, due to the influence of the WMA on 14C specific activities in the swamp. In addition, it was possible to identify two groups of sites, each showing significant exponential declines with distance from the groundwater source area. One of the groups showed relatively more elevated 14C specific activities at a given distance from source, likely due to their proximity to the WMA, the location of the sub-surface plume originating from the WMA, the presence of marsh and swamp habitat types, which facilitated 14C transport to the atmosphere, and possibly, 14C air dispersion patterns along the eastern edge of the swamp. The other group, which had lower 14C specific activities at a given distance from the groundwater source area, included locations that were more distant from the WMA and the sub-surface plume, and contained fen habitat, which is known to act as barrier to groundwater flow. The findings suggest that proximity to source, groundwater flow patterns and habitat physical characteristics can play an important role in the dynamics of 14C being carried by discharging groundwater into terrestrial and wetland environments. - Highlights: • Groundwater represents an important source of volatile radionuclides to wetlands. • Habitat type influenced 14C transport from sub-surface to surface environments. • C-14 specific activity

  4. Effect of substitutions on 3d magnetism in Gd2Fe14-xMxC compounds, with M=Ni, Si, Cu or V

    International Nuclear Information System (INIS)

    Results of magnetic measurements and 57Fe Moessbauer spectroscopy performed on Gd2Fe14-xMxC compounds, with M=Ni, Si, Cu or V are presented. As M is substituted for Fe, the six crystallographically inequivalent iron sites split into seven inequivalent sites for M=Si, Cu, V, or eight for M=Ni. The analysis of the hyperfine fields and relative intensities supports a preferential distribution of the substitutional elements on the Fe lattice sites. The effects of the substitutional elements on Curie temperatures and anisotropy fields as well as on Fe hyperfine parameters are discussed on the grounds of the preferential Fe site occupancy. (orig.)

  5. Evaluating the interactions of organic compounds with multi-walled carbon nanotubes by self-packed HPLC column and linear solvation energy relationship

    International Nuclear Information System (INIS)

    Highlights: • The HPLC-based approach using CNTs as stationary phase is introduced. • The interactions of nine compounds to MWCNTs are evaluated by retention factors. • The LSER theory is adopted to probe the interactions of the compounds with MWCNTs. • π-/n-Electrons-dependent polarizable interaction plays a key role for adsorption. -- Abstract: Understanding the interactions between organic pollutants and carbon nanotubes (CNTs) is critical for fate assessment of both CNTs and organic pollutants. In this study, the chromatographic approach was introduced based on CNTs as stationary phase for the evaluation of such interactions. The pristine multi-walled carbon nanotubes (MWCNTs) were packed into columns of high-pressure liquid chromatography (HPLC) and the retention factors (k′) were determined to characterize the adsorption affinity of organic compounds onto MWCNTs. Nine compounds were tested. The results showed that their ln k′ values followed the order: benzene < toluene < phenol < chlorobenzene < bromobenzene < aniline < sulfamethoxazole < sulfadiazine ≈ sulfadimidine. The linear solvation energy relationship (LSER) theory was adopted to correlate ln k′ with the molecular solvatochromic parameters. We found that ln k′ of the studied compounds correlate positively with molecular polarizability (E) significantly, suggesting that the π-/n-electrons-dependent polarizable interactions play a major role for the adsorption. Moreover, the thermodynamic parameters calculated from van’t Hoff equations revealed that the interactions between the compounds and MWCNTs were spontaneous and exothermic processes

  6. Evaluating the interactions of organic compounds with multi-walled carbon nanotubes by self-packed HPLC column and linear solvation energy relationship

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Yingqian; Li, Xuehua, E-mail: lixuehua@dlut.edu.cn; Xie, Hongbin; Fu, Zhiqiang; Yang, Xianhai; Qiao, Xianliang; Cai, Xiyun; Chen, Jingwen

    2013-12-15

    Highlights: • The HPLC-based approach using CNTs as stationary phase is introduced. • The interactions of nine compounds to MWCNTs are evaluated by retention factors. • The LSER theory is adopted to probe the interactions of the compounds with MWCNTs. • π-/n-Electrons-dependent polarizable interaction plays a key role for adsorption. -- Abstract: Understanding the interactions between organic pollutants and carbon nanotubes (CNTs) is critical for fate assessment of both CNTs and organic pollutants. In this study, the chromatographic approach was introduced based on CNTs as stationary phase for the evaluation of such interactions. The pristine multi-walled carbon nanotubes (MWCNTs) were packed into columns of high-pressure liquid chromatography (HPLC) and the retention factors (k′) were determined to characterize the adsorption affinity of organic compounds onto MWCNTs. Nine compounds were tested. The results showed that their ln k′ values followed the order: benzene < toluene < phenol < chlorobenzene < bromobenzene < aniline < sulfamethoxazole < sulfadiazine ≈ sulfadimidine. The linear solvation energy relationship (LSER) theory was adopted to correlate ln k′ with the molecular solvatochromic parameters. We found that ln k′ of the studied compounds correlate positively with molecular polarizability (E) significantly, suggesting that the π-/n-electrons-dependent polarizable interactions play a major role for the adsorption. Moreover, the thermodynamic parameters calculated from van’t Hoff equations revealed that the interactions between the compounds and MWCNTs were spontaneous and exothermic processes.

  7. Temperature effects on the behavior of carbon 14 in nuclear graphite

    Energy Technology Data Exchange (ETDEWEB)

    Silbermann, G. [Institut de Physique Nucléaire de Lyon, CNRS/IN2P3, UMR 5822, Université Claude Bernard Lyon 1, Université de Lyon, 4 Rue Enrico Fermi, F-69622 Villeurbanne cedex (France); EDF/DIN/CIDEN/DIE, 154 Avenue Thiers, CS 60018, Lyon 69458 (France); Moncoffre, N., E-mail: n.moncoffre@ipnl.in2p3.fr [Institut de Physique Nucléaire de Lyon, CNRS/IN2P3, UMR 5822, Université Claude Bernard Lyon 1, Université de Lyon, 4 Rue Enrico Fermi, F-69622 Villeurbanne cedex (France); Toulhoat, N. [Institut de Physique Nucléaire de Lyon, CNRS/IN2P3, UMR 5822, Université Claude Bernard Lyon 1, Université de Lyon, 4 Rue Enrico Fermi, F-69622 Villeurbanne cedex (France); Commissariat à l’énergie atomique CEA/DEN, Centre de Saclay, Gif sur Yvette 91191 (France); Bérerd, N. [Institut de Physique Nucléaire de Lyon, CNRS/IN2P3, UMR 5822, Université Claude Bernard Lyon 1, Université de Lyon, 4 Rue Enrico Fermi, F-69622 Villeurbanne cedex (France); Institut Universitaire de Technologie, Université Lyon 1, 94 Bd. Niels Bohr, Villeurbanne 69622 (France); Perrat-Mabilon, A. [Institut de Physique Nucléaire de Lyon, CNRS/IN2P3, UMR 5822, Université Claude Bernard Lyon 1, Université de Lyon, 4 Rue Enrico Fermi, F-69622 Villeurbanne cedex (France); Laurent, G. [EDF/DIN/CIDEN/DIE, 154 Avenue Thiers, CS 60018, Lyon 69458 (France); and others

    2014-08-01

    The dismantling of the 1st French generation UNGG (Uranium Naturel Graphite Gas) nuclear reactors operated by the French utility, EDF (Electricité de France) will generate around 17,000 tons of irradiated graphite wastes that have to be disposed of. {sup 14}C is one of the main radioactive dose contributors over 10,000 years. For the management of this waste, it is mandatory to get an accurate estimation of {sup 14}C. The general aim of our work is therefore to simulate the behavior of {sup 14}C in nuclear graphite and to elucidate the coupled and decoupled effects of temperature, irradiation and radiolytic corrosion that mainly influence {sup 14}C behavior in graphite during reactor operation. This paper focuses on the behavior of {sup 13}C implanted into nuclear graphite and used to simulate the presence of {sup 14}C displaced from its original structural site through recoil during neutron irradiation. It aims at evaluating both the temperature and the disorder level of the implanted graphite structure effects on {sup 13}C migration using two complementary techniques, NRA and SIMS, to evaluate the {sup 13}C distribution at the millimeter and micrometer lateral scales respectively. Raman micro-spectroscopy is used to check the graphite structure evolution. The results show that {sup 13}C is not released up to 1600 °C whatever the initial structural disorder level of the implanted graphite. This might be due to the fact that {sup 13}C might be trapped into interstitial clusters. The extrapolation of our results to the behavior of {sup 14}C shows that reactor temperatures (200–500 °C) did not induce any {sup 14}C release. Moreover, as long as there is no gasification of the graphite matrix, high temperatures tend to stabilize {sup 14}C into the remaining graphite structure. This fact has to be considered in case of high temperature purification of {sup 14}C from irradiated graphite.

  8. Carbon doping of gallium arsenide and reflectance difference spectroscopy of compound semiconductors grown by metalorganic vapor-phase epitaxy

    Science.gov (United States)

    Begarney, Michael John

    The surface structure and chemistry of compound semiconductors used in heterojunction bipolar transistors was investigated. Lattice-matched, single crystal films of gallium arsenide and indium phosphide were deposited by metalorganic vapor-phase epitaxy in a horizontal-flow, quartz reactor. Two areas of the transistor fabrication process were studied: (1) carbon doping of the gallium arsenide base layer using carbon tetrachloride, and (2) in-situ monitoring of the surface reconstructions of gallium arsenide and indium phosphide by reflectance difference spectroscopy for improved heterointerface formation. Carbon tetrachloride was found to effect the growth of gallium arsenide in two ways: (1) reaction of chlorine with adsorbed gallium atoms to produce volatile GaCl, and (2) reaction of chlorine with the GaAs film to produce GaCl3. The latter of these reactions was found to be insignificant below a temperature-dependent threshold ratio of chlorine to gallium. At lower values of this ratio, step bunching and pinning was observed, while at higher values, pits ranging from 20 to 50 nm in diameter resulted. We show that these results arise due to the presence of the c(4 x 4) gallium arsenide reconstruction during crystal growth, and the site-specific adsorption of CCl4 at gallium atom sites, which are present only at step edges for this reconstruction. The relationship between the reflectance difference spectra and the atomic structure of arsenic-rich reconstructions of GaAs (001) were investigated. It was found that a roughening process, involving the desorption of arsenic and outdiffusion of gallium atoms to the surface, takes place as the surface structure changes with decreasing arsenic coverage. We determined that the intensity of the negative peak at 2.8 eV strongly depends on the presence of adsorbed alkyl groups and gallium atoms, while, by contrast, the intensity of the positive peak at 2.9 eV is directly proportional to the density of (2 x 4)-type dimers. We

  9. The chemistry of subcritical water reactions of a hardwood derived lignin and lignin model compounds with nitrogen, hydrogen, carbon monoxide and carbon dioxide

    Science.gov (United States)

    Hill Bembenic, Meredith A.

    collected solids from the CO reactions appeared to be the most reacted (i.e., the most changed from the unreacted lignin) according to solid state 13C-NMR analysis, and the widest variety of products (methoxy-substituted phenolic compounds) were obtained when using CO according to GC/MS analysis. Therefore, reactions with CO were completed that varied the initial reaction pressure (300, 500 and 800 psi) in order to elucidate the effects of CO pressure. Similar conversion (≈54--58%) and DCM-soluble liquid product yields (≈53--62%) were obtained for the different pressure reactions, but the reactions with an initial pressure of 500 psi had the greatest change in aromaticity from the unreacted lignin. Additional reactions between Organosolv lignin and H2O with CO (initial pressure of 500 psi) were conducted where the reaction time was varied (15, 30 and 60 min.) to determine the effect of reaction time. Longer reaction time (60 min.) appeared to inhibit conversion to low molecular weight compounds (i.e., conversion and DCM-soluble yields were lower at ≈53% and ≈28%, respectively). Solid state 13C-NMR of collected residues also showed that there are losses in carbons representative of both guaiacyl and syringyl components as reaction time increases, which may indicate that methoxy groups are being cleaved or the products are reacting with each other (i.e., repolymerization) to form high molecular weight compounds as reaction time is increased. The role of H2O and the gases during the baseline reactions and the expanded CO reactions is not intuitive based on the results, so reactions with lignin model compounds (i.e., aromatic aldehydes represented by vanillin and syringaldehyde, aromatic ketones represented by acetovanillone and acetosyringone, and aromatic ethers represented by dibenzyl ether and 2-phenethyl phenyl ether) were completed to study this. From these results, the suggested reaction pathway of Organosolv lignin reactions in subcritical H2O with and without

  10. All-Carbon [3+3] Oxidative Annulations of 1,3-Enynes by Rhodium(III)-Catalyzed C–H Functionalization and 1,4-Migration**

    Science.gov (United States)

    Burns, David J; Best, Daniel; Wieczysty, Martin D; Lam, Hon Wai

    2015-01-01

    1,3-Enynes containing allylic hydrogens cis to the alkyne function as three-carbon components in rhodium(III)-catalyzed, all-carbon [3+3] oxidative annulations to produce spirodialins. The proposed mechanism of these reactions involves the alkenyl-to-allyl 1,4-rhodium(III) migration. PMID:26224377

  11. Synthesis of Nd2Fe14C compound by high-energy ball-milling Nd–Fe alloy in heptane and annealing under vacuum

    Science.gov (United States)

    Geng, H. M.; Ji, Y.; Feng, X. Y.; Zhang, J. J.; Ran, Z.; Yan, Y.; Wang, W. Q.; Su, F.; Du, X. B.

    2016-06-01

    A simple synthesis route for the Nd2Fe14C compound with good permanent magnetic properties is presented. Being high-energy ball-milled in heptane (C7H16) for 8 h, the NdFe3.5 alloy consisting of Nd2Fe17 and Nd phases disproportionates into NdH2+δ and α-Fe. Subsequently, NdH2+δ decomposes when annealed from room temperature to 900 °C under vacuum, and H2 is released. Meanwhile Nd2Fe14C, NdC and little α-Fe phases are formed in the final product. H and C atoms come from the decomposition of heptane. Coercivity of 1.39 T and maximum magnetic energy product of 62.7 kJ m‑3 have been achieved. Too short a ball-milling time results in the insufficient disproportionation of NdFe3.5 alloy and the residue of Nd2Fe17 phase in the final product. Too long a ball-milling time results in the appearance of NdC2 and more α-Fe phases besides Nd2Fe14C and NdC phases. Hexane (C6H14), octane (C8H18) and nonane (C9H20) have been proved to have a similar effect to heptane.

  12. Modern climate and vegetation variability recorded in organic compounds and carbon isotopic compositions in the Dianchi watershed.

    Science.gov (United States)

    Xu, Meina; Wang, Yanhua; Yang, Hao; Xie, Biao; Niu, Xiaoyin

    2015-09-01

    The aliphatic hydrocarbons distribution and compound-specific characteristics of carbon isotopic compositions in the sediments from the small catchment (197 km(2)) of the Dianchi watershed were investigated for identification of modern climate and vegetation variations in the study area. Results show that a regular bimodal n-alkanes distribution ranged from nC16 to nC33, with strong dominance at nC17 for short-chain n-alkanes and nC31 for long-chain n-alkanes. Mass chromatogram of total fatty acids also indicates corresponding mixed contribution of algae, hydrophilous non-emergent (C4 plants) and terrestrial plants (C3 plants) to sedimentary organic matter (OM). At the depth of -24 to -25 cm (early 1970s), nC31/nC17 and terrestrial to aquatic ratio of hydrocarbons (TAR) values decrease, suggesting a shift of OM origins from C3 terrestrial plants to algae-derived C4 plants. The highest water stage in 1971 was found to be recorded in the particle size (drought resulted in the excessive OM inputs to the watershed. PMID:25976326

  13. Influence of activated carbon preloading by EfOM fractions from treated wastewater on adsorption of pharmaceutically active compounds.

    Science.gov (United States)

    Hu, Jingyi; Shang, Ran; Heijman, Bas; Rietveld, Luuk

    2016-05-01

    In this study, the preloading effects of different fractions of wastewater effluent organic matter (EfOM) on the adsorption of trace-level pharmaceutically active compounds (PhACs) onto granular activated carbon (GAC) were investigated. A nanofiltration (NF) membrane was employed to separate the EfOM by size, and two GACs with distinct pore structures were chosen for comparison. The results showed that preloading with EfOM substantially decreased PhAC uptake of the GACs; however, comparable PhAC adsorption capacities were achieved on GACs preloaded by feed EfOM and the NF-permeating EfOM. This indicates that: (1) the NF-rejected, larger EfOM molecules with an expectation to block the PhAC adsorption pores exerted little impact on the adsorbability of PhACs; (2) the smaller EfOM molecules present in the NF permeate contributed mainly to the decrease in PhAC uptake, mostly due to site competition. Of the two examined GACs, the wide pore-size-distributed GAC was found to be more susceptible to EfOM preloading than the microporous GAC. Furthermore, among the fourteen investigated PhACs, the negatively charged hydrophilic PhACs were generally subjected to a greater EfOM preloading impact. PMID:26891356

  14. Calcium carbonate interaction analysis in polypropylene compounds and their impact on the formation of beta crystalline phase of this polymer

    International Nuclear Information System (INIS)

    The insertion of calcium carbonate (CaCO3) in polypropylene compound is a thoroughly known technique widely studied in the academic area and in the industry. Its wide application is due, mainly, to increase mechanical properties with low manufacturing cost. These improvements in this polymer make it more versatile and competitive compared to other expensive polymers. In this study, the incorporation of four types of CaCO3 from the same manufacturer were compared and the focus was on the size of this mineral filler. Furthermore, it was analyzed the interaction of graphitized polypropylene with maleic anhydride (PP-g-MA) in the same samples. All these samples were analyzed by WAXS and SEM. The physical properties of tensile strength and impact were also analyzed. It was observed from this study that the smallest CaCO3 produced with PP-g-MA resulted in better physical properties with the formation of a crystalline phase beta, as originally studied by other authors using other raw materials. (author)

  15. Linear solvation energy relationship for the adsorption of synthetic organic compounds on single-walled carbon nanotubes in water.

    Science.gov (United States)

    Ding, H; Chen, C; Zhang, X

    2016-01-01

    The linear solvation energy relationship (LSER) was applied to predict the adsorption coefficient (K) of synthetic organic compounds (SOCs) on single-walled carbon nanotubes (SWCNTs). A total of 40 log K values were used to develop and validate the LSER model. The adsorption data for 34 SOCs were collected from 13 published articles and the other six were obtained in our experiment. The optimal model composed of four descriptors was developed by a stepwise multiple linear regression (MLR) method. The adjusted r(2) (r(2)adj) and root mean square error (RMSE) were 0.84 and 0.49, respectively, indicating good fitness. The leave-one-out cross-validation Q(2) ([Formula: see text]) was 0.79, suggesting the robustness of the model was satisfactory. The external Q(2) ([Formula: see text]) and RMSE (RMSEext) were 0.72 and 0.50, respectively, showing the model's strong predictive ability. Hydrogen bond donating interaction (bB) and cavity formation and dispersion interactions (vV) stood out as the two most influential factors controlling the adsorption of SOCs onto SWCNTs. The equilibrium concentration would affect the fitness and predictive ability of the model, while the coefficients varied slightly. PMID:26854726

  16. Biomarkers and compound-specific stable carbon isotope of n-alkanes in crude oils from Eastern Llanos Basin, Colombia

    Science.gov (United States)

    Cortes, Jorge E.; Rincon, Jose M.; Jaramillo, Jose M.; Philp, R. Paul; Allen, Jon

    2010-03-01

    Representative samples of crude oils from Cusiana, Cupiagua, Apiay, Castilla and Chichimene fields in the Eastern Llanos Basin of Colombia were analyzed to determine its compound-specific stable carbon isotope composition (CSIA) using gas chromatography-isotopic ratio-mass spectrometry (GC-IRMS). GC-IRMS analyses of n-alkanes allowed differentiating between Cretaceous and Cretaceous/Tertiary oil samples. Cretaceous sourced samples have δ13C-enriched values than Cretaceous/Tertiary sourced samples; the heavier isotope composition of these samples is due to their major terrigenous organic matter input. Their isotope distribution patterns suggest significant algal and/or bacterial contribution (marine origin). The analysis of the n-alkane fractions by GC-IRMS confirms that the organic matter has marine origin in those samples from Cusiana, Cupiagua and Apiay while Castilla and Chichimene have marine origin with terrestrial inputs. The results were confirmed by gas chromatography/FID and gas chromatography/mass spectrometry (GC/MS). Basic geochemical composition show that samples from Cupiagua/Cusiana fields and Apiay/Castilla/Chichimene fields in the Llanos basin, Colombia present different characteristics reflecting a specific for each depositional environment.

  17. Spatial Distribution and Dynamics of Carbon-14 in a Wetland Ecosystem

    International Nuclear Information System (INIS)

    There is significant interest in assessing the impact of 14C releases from nuclear facilities, radioactive waste management areas, and geologic disposal facilities. As a result, there is a general need to gain understanding of 14C dynamics, especially in complex interface ecosystems, such as wetlands. This paper summarizes the key findings of two studies undertaken in Duke Swamp, a circa 0.1 km2 area of wetland consisting of marsh, fen and swamp habitats, on the Atomic Energy of Canada Limited (AECL)'s Chalk River Laboratories Site. The swamp receives radionuclides, such as 14C and tritium, from an up-gradient waste management area. The first study was an extensive field sampling campaign, involving collection of surface vegetation at 69 locations on a 50 m x 50 m grid, to evaluate the spatial distribution of 14C in Duke Swamp. Representative receptor plants and animals, and corresponding environmental media (including air, soil, and plant) samples were then collected, as part of a second study, at a subset of six locations with 14C specific activities that spanned the range present in Duke Swamp and also represented the different wetland habitats occurring there. The highest specific activity concentrations in surface vegetation were highly localized, representing a surface area of only about 150 m2. The spatial distribution of 14C in the swamp seemed to be at least partly accounted for by the physical attributes of the Duke Swamp habitat. In general, it was found that specific activities of 14C in biota tissues reflected those measured in surface vegetation collected from the same sampling location. Such information provides needed insight for biosphere assessments, as well as for the development of monitoring programs that demonstrate protection of biota in areas where exposure to 14C is elevated. (authors)

  18. Implications for chloro- and pheopigment synthesis and preservation from combined compound-specific δ13C, δ15N, and Δ14C analysis

    Directory of Open Access Journals (Sweden)

    G. Mollenhauer

    2010-08-01

    Full Text Available Chloropigments and their derivative pheopigments preserved in sediments can directly be linked to photosynthesis. Their carbon and nitrogen stable isotopic compositions have been shown to be a good recorder of recent and past surface ocean environmental conditions tracing the carbon and nitrogen sources and dominant assimilation processes of the phytoplanktonic community. In this study we report results from combined compound-specific radiocarbon and stable carbon and nitrogen isotopic analysis to examine the timescales of synthesis and fate of chlorophyll-a and its degradation products pheophytin-a, pyropheophytin-a, and 132,173-cyclopheophorbide-a-enol until burial in Black Sea surface sediments. The pigments are mainly of marine phytoplanktonic origin as implied by their stable isotopic compositions. Pigment δ15N values indicate nitrate as the major uptake substrate but 15N-depletion towards the open marine setting indicates contribution from N2-fixation. Radiocarbon concentrations translate into minimum and maximum pigment ages of approximately 40 to 1200 years. This implies that protective mechanisms against decomposition such as association with minerals or eutrophication-induced hypoxia and light limitation are much more efficient than previously thought. However, seasonal variations of nutrient source, growth period, and habitat and their associated isotopic variability are likely at least as strong as long-term trends. Combined triple isotopic analysis of sedimentary chlorophyll and its primary derivatives is a powerful tool to delineate biogeochemical and diagenetic processes in the surface water and assess their precise timescales.

  19. Characteristics of compound multiplicity in 28Si-Em interactions at 14.6 A GeV

    International Nuclear Information System (INIS)

    The multiplicity of charged particles in high energy nucleus-nucleus interactions is an important parameter which indicates how many particles are produced in that interaction. The multiplicity distributions of produced particles help in learning the interaction mechanism. Generally, it is accepted that in high energy nucleus-nucleus collisions, the emission of fast target associated particles mostly the knocked out protons known as grey particles, takes place at a relatively latter stage of the collision. These fast protons with range L ≥3 mm and relative velocity 0.3 ≤ β ≤0.7 lies in the energy range 30-400 MeV. Moreover, these grey particles (Ng) are often assumed to be the measure of the number of encounters made by the incident hadron inside the target nucleus. Also the particles produced in the first stage of collision with relative velocity β ≥0.7 are known as relativistic shower particles (Ns). These particles are mostly pions with a small admixture of charged K-mesons and fast protons. The analysis of the experimental data in terms of multiplicity distributions for grey and shower particles collectively known as compound multiplicity (i.e. Nc = Ng + Ns) introduced by Jurak and Linscheid is one of the main source of information about the mechanism of particle production. Many workers analyzed the data on nucleus-nucleus (A-A) and h-A collisions to investigate some interesting features of compound multiplicity distribution

  20. Carbon 14 transfer from seawater to the atmosphere through degassing processes in the Bay of Seine (Northwest France)

    International Nuclear Information System (INIS)

    COGEMA La Hague nuclear reprocessing plant is located in the North West of Cotentin peninsula near Cherbourg (France). This nuclear plant releases radioelements in atmosphere and in the English Channel. About 8.5 TBq.year-1 of radiocarbon are released as the liquid wastes through a pipe a few kilometres off sea shore, West of the reprocessing plant (COGEMA data). Recent studies in the peninsula show anomalous higher radiocarbon contents in vegetation near the coast that have suggested a supplementary marine contribution through the degassing of the 14C excess supplied by liquid releases of the nuclear plant. Carbon dioxide partial pressure, 14C activities were measured in air and sea water in the Bay of Seine and around the COGEMA-La Hague nuclear reprocessing plant during three cruises in 2000 and 2002. Results show clearly that sea is a source of CO2 and 14C to the atmosphere. Higher 14C concentrations in air and water related to the La Hague liquid wastes are clearly recorded. The aim of this paper is to show results of these oceanographic campaigns. Flux between seawater and atmosphere are calculated in the northwest Cotentin and in Bay of Seine. (author)

  1. Seasonal and snowmelt-driven changes in the water-extractable organic carbon dynamics in a cool-temperate Japanese forest soil, estimated using the bomb-14C tracer

    International Nuclear Information System (INIS)

    Water-extractable organic carbon (WEOC) in soil consists of a mobile and bioavailable portion of the dissolved organic carbon (DOC) pool. WEOC plays an important role in dynamics of soil organic carbon (SOC) and transport of radionuclides in forest soils. Although considerable research has been conducted on the importance of recent litter versus older soil organic matter as WEOC sources in forest soil, a more thorough evaluation of the temporal pattern of WEOC is necessary. We investigated the seasonal variation in WEOC in a Japanese cool-temperate beech forest soil by using the carbon isotopic composition (14C and 13C) of WEOC as a tracer for the carbon sources. Our observations demonstrated that fresh leaf litter DOC significantly contributed to WEOC in May (35–52%) when the spring snowmelt occurred because of the high water flux and low temperature. In the rainy season, increases in the concentration of WEOC and the proportion of hydrophobic compounds were caused by high microbial activity under wetter conditions. From summer to autumn, the WEOC in the mineral soil horizons was also dominated by microbial release from SOC (>90%). These results indicate that the origin and dynamics of WEOC are strongly controlled by seasonal events such as the spring snowmelt and the rainy season's intense rainfall. -- Highlights: • 14C and 13C were used for a tracer for the carbon sources of WEOC in a forest soil. • Fresh leaf litter DOC significantly contributed to WEOC in the spring snowmelt. • Microbial activity caused the increase of WEOC concentration in the rainy season

  2. Removal of pharmaceutical compounds from water by adsorption on activated carbon and degradation with ozone; Eliminacion de compuestos farmaceuticos de las aguas por adsorcion en carbon activado y degradacion con ozono

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez Polo, M.; Prado Joya, G.; Rivera Utrilla, J.; Ferro Garcia, M. A.; Bautista Toledo, M. I.; Lopez Penalver, J. J.; Gomez Merlo de la fuente, C.

    2007-07-01

    The removal of pharmaceutical compounds from water, using nitroimidazoles as model compounds, by means of both adsorption on activated carbon and ozonization has been studied. The results obtained have shown that activated carbon presents a great efficiency to remove these contaminants from waters because: the adsorption kinetics is very fast, and it is not affected by diffusion problems; the maximum adsorption capacity is very high (400-96 mg/g); and the nitroimidazole adsorption capacity is enhanced in natural waters. Regarding to the ozonization process, a low reactivity of these compounds with ozone has been observed (k{sub 0}3{approx_equal}100 M{sup -}1 s{sup -}1) although, nevertheless, they present a high affinity to the hydroxyl radicals (k{sub O}H{approx_equal}10{sup 1}0 M{sup -}1s{sup -}1). (Author) 13 refs.

  3. Cu Insertion Into the Mo12 Cluster Compound Cs2Mo12Se14: Synthesis, Crystal and Electronic Structures, and Physical Properties.

    Science.gov (United States)

    Al Rahal Al Orabi, Rabih; Fontaine, Bruno; Gautier, Regis; Gougeon, Patrick; Gall, Philippe; Bouyrie, Yohan; Dauscher, Anne; Candolfi, Christophe; Lenoir, Bertrand

    2016-07-01

    Mo-based cluster compounds are promising materials for high-temperature thermoelectric applications due to their intrinsic, extremely low thermal conductivity values. In this study, polycrystalline cluster compounds Cs2CuxMo12Se14 were prepared for a wide range of Cu contents (0 ≤ x ≤ 2). All samples crystallize isostructurally in the trigonal space group R3̅. The position of the Cu atoms in the unit cell was determined by X-ray diffraction on a single-crystalline specimen indicating that these atoms fill the empty space between the Mo-Se clusters. Density functional theory calculations predict a metallic ground state for all compositions, in good agreement with the experimental findings. Magnetization measurements indicate a rapid suppression of the superconducting state that develops in the x = 0.0 sample upon Cu insertion. Transport properties measurements, performed in a wide temperature range (2-630 K) on the two end-member compounds x = 0 and x = 2, revealed a multiband electrical conduction as shown by sign reversal of the thermopower as a function of temperature. PMID:27304903

  4. Evaluation of carbon-14 (C{sup 14}) levels of terrestrial and marine food products of the environment of the site of Cogema La Hague; Evaluation des niveaux de carbone-14 ({sup 14}C) des denrees alimentaires terrestres et marines de l'environnement du site de COGEMA - La Hague

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-04-15

    This evaluation has for object to inform about the levels in carbon 14 in the environment of the factories of La Hague. Two sectors were differentiated on one hand the terrestrial environment, and on the other hand the marine environment. The investigations concerned first and foremost food products stemming as the vegetable culture (vegetables) or individual breeding (milk, eggs) but also foodstuffs stemming from the local agriculture (cereal). In touch with the second sector, the marine environment, the sampling concerned the accessible products of the sea by all and those locally marketed (fishes, molluscs, shellfishes). The different results are presented in tables. (N.C.)

  5. Carbon and 14C distribution in tropical and subtropical agricultural soils

    Science.gov (United States)

    Prastowo, Erwin; Grootes, Pieter; Nadeau, Marie

    2016-04-01

    Paddy soil management affects, through the alternating anoxic and oxic conditions it creates, the transport and stabilisation of soil organic matter (SOM). Irrigation water may percolate more organic materials - dissolved (DOM) and colloidal - into the subsoil during anoxic conditions. Yet a developed ploughpan tends to prevent C from going deeper in the subsoil and partly decouple C distribution in top and sub soil. We investigate the influence of different soil type and environment. We observed the C and 14C distribution in paddy and non-paddy soil profiles in three different soil types from four different climatic regions of tropical Indonesia, and subtropical China. Locations were Sukabumi (Andosol, ca. 850 m a.s.l), Bogor (clayey Alisol, ca. 240 m a.s.l), and Ngawi (Vertisol, ca. 70 m a.s.l) in Jawa, Indonesia, and Cixi (Alisol(sandy), ca. 4 - 6 m a.s.l) in Zhejiang Province, China. We compared rice paddies with selected neighbouring non-paddy fields and employed AMS 14C as a tool to study C dynamics from bulk, alkali soluble-humic, and insoluble humin samples, and macrofossils (plant remains, charcoal). Our data suggest that vegetation type determines the quantity and quality of biomass introduced as litter and root material in top and subsoil, and thus contributes to the soil C content and profile, which fits the 14C signal distribution, as well as 13C in Ngawi with C4 sugar cane as upland crop. 14C concentrations for the mobile humic acid fraction were generally higher than for bulk samples from the same depth, except when recent plant and root debris led to high 14C levels in near-surface samples. The difference in sampling, - averaged layer for bulk sample and 1-cm layer thickness for point sample - shows gradients in C and 14C across the layers, which could be a reason for discrepancies between the two. High 14C concentrations - in Andosol Sukabumi up to 111 pMC - exceed the atmospheric 14CO2concentration in the sampling year in 2012 (˜ 103 pMC) and

  6. The long-term trend of carbon-14 level in Japan

    International Nuclear Information System (INIS)

    The long-term trend of the specific activity of 14C in terms of dpm/gC from 1942 to 1991 in the natural environment in Japan was obtained as baseline data by analyzing plant components so as to evaluate the collective effective dose. It was deduced that the specific activity of 14C in plants reflected well that of atmospheric 14CO2. Uniform distribution of the specific activity in plant among species as well as the production places was confirmed. The Suess effect was observed clearly for a period of 10 years from the late 1960's. The 14C level was at about 13.7 dpm/gC due to cosmic ray production in 1940's, and reached a peak of about 24.5 dpm/gC in 1963 due to nuclear weapons testing and decreased to 15.6 dpm/gC in 1991. Fermented alcohol proved to be a convenient indicator for measuring the annual mean specific activity of 14C in the atmosphere. (3 figs.)

  7. PRIORITY. Improved oil recovery and productivity from Lower Cretaceous Carbonates. 1.4.c: Compaction of Lower Cretaceous Carbonates

    Energy Technology Data Exchange (ETDEWEB)

    Foged Christensen, H.; Roedbro, L. [GEO (Denmark); Krogsboell, A. [BYG-DTU (Denmark)

    2002-09-01

    The in-situ stress state in the Valdemar field is unknown, especially with respect to the horizontal stress state. The horizontal stress state (or confining stress) is known to affect the compressibility and compaction properties of a material. The objective of this study is to evaluate the effect of different stress ratios and different loading rates on the compaction properties. Finally, the effect of water flooding (water weakening) on strength and deformation properties is studied. Two triaxial compaction tests, three constant rate of strain (CRS) oedometer tests and two waterflooding tests have been carried out on medium to high porosity non-fractured oil-saturated Valdemar Lower Cretaceous carbonate, representing the Lower Cretaceous Upper Tuxen 1 and Middle Tuxen 1 formations. The deformation properties for the elastic and plastic stress regime have been expressed in terms of the oedometric modulus, K, and a number of reloading moduli, K{sub rel}, for the corresponding fixed horizontal to vertical stress ratios. The compaction tests showed that the reloading moduli increase with increasing confining pressure. The de Waal creep parameters (bc{sub m0}, product of the de Waal dynamic friction parameter and the uniaxial compressibility) is derived from curve fitting of strain/time curves, in order to correlate laboratory to field pore collapse stress. The waterflooding tests indicated a reduction of the pore collapse stress in the order of 1000-1500 psi, comparable to the water weakening effect observed on Upper Cretaceous chalk. Further, a time delay with respect to responding to waterflooding of the material is observed. (au)

  8. Synthesis of 1-[14C]methyl-1H-tetrazole-5-thiol([14C]NMTT) and [NMTT-[14C

    International Nuclear Information System (INIS)

    The title compounds were prepared for metabolic studies, with the 14C labelling being made at methyl of the 1-methyl-1H-tetrazol-5-ylthio (NMTT) group in overall radiochemical yields of 26% and 22% based on barium [14C]carbonate, respectively. (author)

  9. A comet could not produce the carbon-14 spike in the 8th century

    CERN Document Server

    Usoskin, Ilya

    2014-01-01

    A mysterious increase of radiocarbon 14C ca. 775 AD in the Earth's atmosphere has been recently found by Miyake et al. (Nature, 486, 240, 2012). A possible source of this event has been discussed widely, the most likely being an extreme solar energetic particle event. A new exotic hypothesis has been presented recently by Liu et al. (Nature Sci. Rep., 4, 3728, 2014) who proposed that the event was caused by a comet bringing additional 14C to Earth. Here we calculated a realistic mass and size of such a comet to show that it would have been huge (~100 km across and 10^{14}-10^{15} ton of mass) and would have produced a disastrous impact on Earth. Such an impact could not remain unnoticed in the geological records and chronicles. The absence of an evidence for such a dramatic event makes this hypothesis invalid.

  10. On the labelling of insuline and insuline derivatives with tritium and carbon-14

    International Nuclear Information System (INIS)

    Two different labelling methods were investigated. By means of the Wilzbach labelling with diaminosuberoylinsuline the insuline is irreversibly altered. As a second method the reductive methylation was used, in doing so it was possible to distinguish between mono and dimethylated parts of the reaction product by using C-14 labelled formaldehyde. Furthermore four N,N-dimethylated insuline derivatives were isolated with yields of 25 until 35%. By using C-14 and h-3 labelled reagents insuline can be labelled doubly. Moreover N-terminal amino groups could be protected irreversibly with this method. Furthermore structure-function investigations and investigations concerning the insuline metabolism were done. (SPI)

  11. Constraints on emissions of carbon monoxide, methane, and a suite of hydrocarbons in the Colorado Front Range using observations of 14CO2

    OpenAIRE

    LaFranchi, B. W; Pétron, G.; Miller, J. B.; S. J. Lehman; Andrews, A. E; E. J. Dlugokencky; Hall, B.; Miller, B. R.; Montzka, S. A.; W. Neff; P. C. Novelli; C. Sweeney; J. C. Turnbull; D. E. Wolfe; P. P. Tans

    2013-01-01

    Atmospheric radiocarbon (14C) represents an important observational constraint on emissions of fossil-fuel derived carbon into the atmosphere due to the absence of 14C in fossil fuel reservoirs. The high sensitivity and precision that accelerator mass spectrometry (AMS) affords in atmospheric 14C analysis has greatly increased the potential for using such measurements to evaluate bottom-up emissions inventories of fossil fuel CO2 (CO2ff), as well as those for other co-emitte...

  12. Syntheses of γ-aminobutyric-1-14C and of α-aminoadipic-6-14C acid from methoxy-3 chloropropyl-magnesium and marked carbon dioxide

    International Nuclear Information System (INIS)

    Carbonation of γ-methoxypropyl-magnesium chloride by CO2 gives γ-methoxy-butyric carboxylic-14C acid with a yield of about 95 per cent. When the latter is treated successively with anhydrous HBr and with diazomethane, methyl carboxylic γ-bromobutyrate-14C is formed. This in turn gives γ-amino-butyric carboxylic-14C acid with an overall yield of 66 per cent with respect to Ba14CO3, when it is condensed with potassium phthalimide and hydrolyzed by acid. By reacting methyl-γ-bromobutyrate-14C with the sodium derivative of ethyl cyanacetamido-acetate in ethanol, followed by an acid hydrolysis, α-aminoadipic-6-14C acid is obtained with an overall yield of 46 per cent with respect to Ba14CO3. (author)

  13. Carbon beam extraction with 14.5 GHz electron cyclotron resonance ion source at Korea Atomic Energy Research Institute.

    Science.gov (United States)

    Lee, Cheol Ho; Oh, Byung-Hoon; Chang, Dae-Sik; Jeong, Sun-Chan

    2014-02-01

    A 14.5 GHz Electron Cyclotron Resonance ion source (ECRIS) has been made to produce C(4+) beam for using a carbon therapy facility and recently tested at KAERI. Highly charged carbon ions have been successfully extracted. When using only CO2 gas, the beam current of C(4+) was almost 14 μA at 15 kV extraction voltage. To get higher current of the C(4+) beam, while optimizing confinement magnetic field configuration (e.g., axial strengths at minimum and extraction side), gas-mixing (CO2/He), and biased disk were introduced. When the gas mixing ratio of the CO2/He gas is 1:8 at an operational pressure of 5 × 10(-7) mbar and the disk was biased to -150 V relative to the ion source body, the highest current of the C(4+) beam was achieved to be 50 μA, more than three times higher than previously observed only with CO2 gas. Some details on the operating conditions of the ECRIS were discussed. PMID:24593482

  14. Synthesis of carbon-14 and tritium labelled forms of bupropion hydrochloride - a novel antidepressant

    International Nuclear Information System (INIS)

    Bupropion hydrochloride (2-tert-butylamino-3'-chloropropiophenone hydrochloride) was synthesized in the [14C]-labelled form with specific activity 36.5mCi/mmol suitable for drug metabolism, distribution and pharmacokinetic studies. The drug was synthesized in the [3H]-labelled form with specific activity 20.5 Ci/mmol suitable for development of a radioimmunoassay procedure. (author)

  15. Carbon-14 labelled nitrogen heterocycles; the syntheses of three phosphodiesterase inhibitors

    International Nuclear Information System (INIS)

    The syntheses of three heterocyclic phosphodiesterase inhibitors are described from a common radiolabelled precursor, namely 2-propoxybenzo[cyano-14C] nitrile. Conversion of the nitrile to the corresponding methyl ketone or amidine allows elaboration of the heterocycles radiolabelled within the ring systems. (Author)

  16. Carbon-14 based determination of the biogenic fraction of industrial CO2 emissions : Application and validation

    NARCIS (Netherlands)

    Palstra, S. W. L.; Meijer, H. A. J.

    2010-01-01

    The C-14 method is a very reliable and sensitive method for industrial plants, emission authorities and emission inventories to verify data estimations of biogenic fractions of CO2 emissions. The applicability of the method is shown for flue gas CO2 samples that have been sampled in I-h intervals at

  17. Interactive effects between carbon allotropes on the mechanical reinforcement of nanocomposites based on poly(1,4-cis-isoprene)

    Science.gov (United States)

    Musto, Sara; Cipolletti, Valeria; Barbera, Vincenzina; Agnelli, Silvia; Pandini, Stefano; Galimberti, Maurizio

    2014-05-01

    Interactive effects of carbon allotropes on the mechanical reinforcement of polymer nanocomposites were investigated by using, as the polymer matrix, poly(1,4-cis-isoprene) (PI) samples from industrial synthesis and from natural sources. Carbon nanotubes (CNT) and nano-graphite with high shape anisotropy (nanoG) were melt blended with PI, as the only fillers or in combination with carbon black (CB), measuring the shear modulus at low strain amplitudes. The nanofiller was found to increase the low amplitude storage modulus of the matrix, with or without CB, by a factor depending on nanofiller type and content. The filler-polymer interfacial area was able to correlate modulus data of composites with CNT, CB and with the hybrid filler system, leading to the construction of a common master curve. The filler networking phenomenon was found to be affected by type and amount of low molecular mass products of PI from natural sources. The correlation between chemical composition, dynamic mechanical and ultimate properties of nanocomposites was investigated. In particular, it was found that low molecular mass components control the ability of elastomeric nano-composites to store or dissipate energy.

  18. Geochemical identification of coal-sourced oils and interbedded shale-sourced oils as revealed by compound specific carbon isotopic analysis

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    To date, questions remain as to how to differen tiate between coal- and interbedded shale-sourced oils in coal measures. Based on the hypothesis that δ13C value of sedimentary organic matter is controlled by the depositional environment and productivities of biota grown in such depositional setting, this note examines compound specific carbon isotopic profiles from coal and interbedded shale extracts using the gas chromatography-isotope ratio mass spectrometry technique (GC/IRMS). The results show that compound specific carbon isotope values from coal extracts are enriched in 13C relative to that of interbedded shale extracts, and provide useful information in characterizing coal- and interbedded shale-sourced oils in coal measures. An example for its successful application from the Turpan Basin, Northwestern China is presented.

  19. Geochemical investigations into the retention of reactive carbon compounds for toxic heavy metals. Final report; Geochemische Untersuchungen zur Retention von reaktiven Kohlenstoffverbindungen fuer toxische Schwermetalle. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Kupsch, H.; Mansel, A.; Crustewitz, C.

    2003-03-01

    The composition, reactivity and stability of reactive organic carbon compounds adsorbed on geogenic matrices was investigated. The surface deposits of NOM and its dependence on geochemical parameters was investigated in selected geomatrices. The retention of toxic heavy metals on these surface deposits of NOM was investigated in consideration of the presence of hydroxy species and inorganic ligands. The investigations of the reactivity of the NOM species requires analyses of these compounds and of the heavy metals in the ultratracer region. This was possible by means of radiochemical methods that were further developed in the context of this project. Radioactive labeling of identified reactive carbon compounds, e.g. with radioactive iodine, on the one hand, and the use of radioactive Cu, Pb, Hg isotopes on the other hand enabled speciation analyses in the binary systems (heavy metal + geomatrix, heavy metal + reactive carbon compounds, reactive carbon compounds + geomatrix) and especially in the ternary system (heavy metal + geomatrix + reactive carbon compounds) in defined conditions. The special labelling techniques were a precondition for distribution measurements in the near-natural, low concentration range. (orig.) [German] Ziel des Projektes war es, mit der vorhandenen Analytik und Expertise die Zusammensetzung, die Reaktivitaet und die Stabilitaet der auf den geogenen Matrizes sorbierten reaktiven organischen Kohlenstoffverbindungen und die damit verbundenen Stoffumsaetze aufzuklaeren. An ausgewaehlten Geomatrizes wurde die Ausbildung von Oberflaechendepositen des NOM und deren Abhaengigkeit gegenueber geochemischen Parametern untersucht. Unter der Beruecksichtigung der Gegenwart von Hydroxyspezies und anorganischen Liganden wurde die Retention toxischer Schwermetalle an diesen Oberflaechendepositen des NOM untersucht. Die Untersuchungen zur Reaktivitaet der NOM-Spezies setzt eine Analytik dieser Verbindungen und der Schwermetalle im Ultraspurenbereich

  20. Coupling Noble Metals and Carbon Supports in the Development of Combustion Catalysts for the Abatement of BTX Compounds in Air Streams

    OpenAIRE

    Sergio Morales-Torres; Francisco Carrasco-Marín; Agustín F. Pérez-Cadenas; Francisco José Maldonado-Hódar

    2015-01-01

    The catalytic combustion of volatile organic compounds (VOCs) is one of the most important techniques to remove these pollutants from the air stream, but it should be carried out at the lowest possible temperature, saving energy and avoiding the simultaneous formation of nitrogen oxides (NOx). Under these experimental conditions, the chemisorption of water generated from VOCs combustion may inhibit hydrophilic catalysts. Nowadays, a wide variety of carbon materials is available to be used in ...

  1. 14C dating of freshwater carbonate sediments with special reference to calcareous tufas and laminated lake sediments

    International Nuclear Information System (INIS)

    The sequence of laminated sediment of the lake Gosciaz, Poland, covers more than 13,000 years and is actually the longest sequence known so far. Besides of reconstructing past environmental changes, this sequence offers an excellent possibility for studying natural C-14 variations and calibrating the C-14 time scale in a range beyond 6,000 years B.P. The floating varve chronology based on previously taken sediment cores which cover a period of 9,682 years, has been improved by this study. Relative water level changes of the lake during the past 11,500 years have been reconstructed by means of C-14 and C-13 measurements carried out on carbonate fractions of the lake sediments. Periodical variations in the width of annual layers were found. The periods identified are 11 years and 22 years (solar cycle), 35 years (Bruckner cycle), and 200 years. The ratio of summer layer width and the total width of the annual layer shows secular changes which correlate with paleotemperature records. The duration of the Younger Dryas period was determined by combining the floating varve chronology with isotope and pollen analyses of the sediment material. A value of 1,500 years was found. The study also included radiocarbon dating of calcareous tufa taken from different study areas. 26 refs, 26 figs, 6 tabs

  2. The contribution of vehicular emission to the atmospheric concentrations of carbon compounds in the Metropolitan Area of Sao Paulo

    Science.gov (United States)

    Andrade, M.; Fornaro, A.; Miranda, R.; Ynoue, R. Y.; Freitas, E. D.; LAPAt-Laboratorio de Analise dos Processos Atmosfericos

    2013-05-01

    It is recognized that megacities have regional and global effects on climate, and that aerosols and Green House Gases (GHG) constitute the principal tracer of those effects. Such is the case in the Metropolitan Area of Sao Paulo (MASP), one of the largest mega-cities in the world. MASP has a population of almost 20 million inhabitants. The main source of air pollution is the transport sector. In this region, there are approximately 6.5 million passenger cars and commercial vehicles: 85% light duty, 3% heavy-duty diesel vehicles (diesel + 3% bio-diesel) and 12% motorcycles. Of the light duty vehicle, approximately 55% burn a mixture (v/v) of 78% gasoline with 22% ethanol (referred to as gasohol), 4% use hydrated ethanol (95% ethanol + 5% water), 38% flexible fuel vehicles capable of burning both gasohol as hydrated ethanol, and 2% use diesel. In average 50% of the fuel used in MASP is ethanol what brings the necessity of more studies to understand the formation of photochemical oxidants and secondary particles. According to the São Paulo State Environmental Protection Agency, 97% of carbon monoxide (CO), 85% of hydrocarbons (HC), 82% of nitrogen oxides (NOx), 36% of sulfur dioxide emitted, and 36% of all inhalable particulate matter (PM10) are emitted by the vehicular fleet. Concerning particles, 75% of the Fine Particle Concentration is related to the burning of fuel, mainly diesel. The fine particles are composed of Organic Carbon (40%), Black Carbon (30%), ions (15%) and metals. It is known that the soot is warming the climate and is important to the radiative balance. Another important driver to the radiative balance, the CO2 is mainly emitted by the transport sector, which is responsible for 57% of its emission. A comprehensive project under development has the objective of determine the role of MASP as the source of gaseous and particle compounds to the atmosphere of the region and in a mesoscale perspective. The project with funding from the São Paulo

  3. The natural thermoluminescence of meteorites. VI - Carbon-14, thermoluminescence and the terrestrial ages of meteorites

    Science.gov (United States)

    Benoit, P. H.; Jull, A. J. T.; McKeever, S. W. S.; Sears, D. W. G.

    1993-06-01

    A relationship is noted between the natural thermoluminescence (TL) levels and the C-14-derived terrestrial ages for meteorite finds from the U.S. Prairie States and Roosevelt County, NM; those in the Sahara are also in accord with calculated TL decay curves, for 'storage' temperatures equal to the approximate average annual temperatures at individual sites. This discussion is limited to the empirical correspondence between the two methodologies, and to theoretical decay curves for a single 'average' ordinary chondrite.

  4. Carbon-14 methylation of the 2-methylbutyryl side chain of mevinolin and its analogs

    International Nuclear Information System (INIS)

    A one step procedure for the preparation of three labeled mevinolin analogs possessing the 2,2-dimethylbutyryloxy side chain is described. Three lactones were converted into potassium salts of their corresponding di or trihydroxy carboxylic acids from which anionic ester enolates were generated and alkylated with [14]methyl iodide. Workup and purification by reverse phase HPLC provided the three radiochemically pure mevinolin analogs. The labeled lactones were converted into ammonium salts of their corresponding di or trihydroxy acids. (author)

  5. Modelling the transfer of tritium and carbon-14 in the environment

    International Nuclear Information System (INIS)

    The important processes in the transfer of 3H and 14C in the environment are reviewed. Relevant parameters and influencing conditions are discussed for sources, atmospheric and hydrologic dispersion, deposition and reemission, incorporation in the biosphere and dosimetric considerations. The uncertainty in the predictions of dynamic tritium models is about a factor of 10. The parameters and processes to which the models are most sensitive are presented as the basis for future work. (author)

  6. Characterization of airborne particulates by pyrolysis/mass spectrometry and carbon-14 analysis

    Energy Technology Data Exchange (ETDEWEB)

    Voorhees, K.J. (Colorado School of Mines, Golden); Durfee, S.L.; Currie, L.A.; Klouda, G.A.

    1981-08-01

    Pyrolysis/mass spectrometry (Py/MS) has been used to characterize the composition of organics in an ambient air particulate sample from the eastern Utah oil shale lands. The procedure involved collection of the individual contributors, pyrolysis of these samples, and finally a least-squares fitting of the individual contributor spectra to the pyrolysis mass spectrum of the ambient sample. The Py/MS results were verified by using /sup 14/C analysis.

  7. Reaction of hydrogen with the Laves phase (C14) TiCr1.78-xMnx compounds

    International Nuclear Information System (INIS)

    The lattice constants a and c of the as cast hexagonal (C14) Laves phase TiCr1.78-xMnx (x = 0, 0.4, 0.6 and 0.8) have been measured by X-ray diffraction at room temperature as a function of the Mn content. It has been found that a decreases with increasing x while c remains almost unchanged. Being this alloy interesting as material for solid state hydrogen storage, pressure-composition isotherms have been traced on desorption mode for the H2 gas pressure and temperature varying from 10 to 0.01 MPa and from 209 to 307 K, respectively. From the temperature dependence of the plateau pressure the molar quantities ΔH-barH2 and ΔS-barH2 associated with the hydride decomposition have been determined as a function of the Mn content. With increasing x, both ΔH-barH2 and ΔS-barH2 progressively decrease, and the desorption pressure initially decreases (for x ≤ 0.4) then slightly increases. At the same time, the pseudo-plateaus become flatter.

  8. Carbon-14 urea breath test for the diagnosis of Campylobacter pylori associated gastritis

    International Nuclear Information System (INIS)

    Urease in the human gastric mucosa is a marker for infection with Campylobacter pylori (CP), an organism suspected of causing chronic gastritis and peptic ulceration. To detect gastric urease, we examined 32 patients who were being evaluated for possible peptic ulcer disease. Fasting patients were given 10 microCi (370 kBq) of 14C-labeled urea. Breath samples were collected in hyamine at intervals between 1 and 30 min. The amount of 14C collected at these times was expressed as: body weight X (% of administered dose of 14C in sample)/(mmol of CO2 collected). The presence of C. pylori colonization was also determined by examination of multiple endoscopic gastric biopsy specimens. On average, patients who were proven to have C. pylori infection exhaled 20 times more labeled CO2 than patients who were not infected. The difference between infected patients and C. pylori negative control patients was highly significant at all time points between 2 and 30 min after ingestion of the radionuclide (p less than 0.0001). The noninvasive urea breath is less expensive than endoscopic biopsy of the stomach and more accurate than serology as a means of detecting Campylobacter pylori infection. Because the test detects actual viable CP organisms, it can be used to confirm eradication of the bacterium after antibacterial therapy

  9. Effects of entrainment through Oconee Nuclear Station on carbon-14 assimilation rates of phytoplankton

    International Nuclear Information System (INIS)

    Carbon assimilation rates of phytoplankton communities entrained through Oconee Nuclear Station were measured on six dates during 1974. Thermal, mechanical, condenser, and multiple entrainment effects on uptake rates were compared by incubating samples in vitro in controlled-temperature water baths. Duplicate light and dark bottles containing water from four cooling-system locations were exposed to temperatures approximating intake and discharge temperatures. The relationships were variable, but exposure of the hypolimnetic intake water at near-discharge temperatures (thermal effect) stimulated primary productivity in four of six experiments. Multiple entrainment and mechanical effects caused no consistent change in assimilation rates

  10. Implications for chloro- and pheopigment synthesis and preservation from combined compound-specific δ13C, δ15N, and Δ14C analysis

    Directory of Open Access Journals (Sweden)

    G. Mollenhauer

    2010-12-01

    Full Text Available Chloropigments and their derivative pheopigments preserved in sediments can directly be linked to photosynthesis. Their carbon and nitrogen stable isotopic compositions have been shown to be a good recorder of recent and past surface ocean environmental conditions tracing the carbon and nitrogen sources and dominant assimilation processes of the phytoplanktonic community. In this study we report results from combined compound-specific radiocarbon and stable carbon and nitrogen isotope analysis to examine the time-scales of synthesis and fate of chlorophyll-a and its degradation products pheophytin-a, pyropheophytin-a, and 132,173-cyclopheophorbide-a-enol until burial in Black Sea core-top sediments. The pigments are mainly of marine phytoplanktonic origin as implied by their stable isotopic compositions. Pigment δ15N values indicate nitrate as the major uptake substrate but 15N-depletion towards the open marine setting indicates either contribution from N2-fixation or direct uptake of ammonium from deeper waters. Radiocarbon concentrations translate into minimum and maximum pigment ages of approximately 40 to 1200 years. This implies that protective mechanisms against decomposition such as association with minerals, storage in deltaic anoxic environments, or eutrophication-induced hypoxia and light limitation are much more efficient than previously thought. Moreover, seasonal variations of nutrient source, growth period, and habitat and their associated isotopic variability are likely at least as strong as long-term trends. Combined triple isotope analysis of sedimentary chlorophyll and its primary derivatives is a powerful tool to delineate biogeochemical and diagenetic processes in the surface water and sediments, and to assess their precise time-scales.

  11. Carbon-14 immobilization via the Ba(OH)28H2O process

    International Nuclear Information System (INIS)

    The airborne release of 14C from various nuclear facilities has been identified as a potential biohazard due to the long half-life of 14C (5730 yrs) and the ease in which it may be assimilated into the biosphere. At Oak Ridge National Laboratory, technology is under development, as part of the Airborne Waste Management Program, for the removal and immobilization of this radionuclide. Prior studies have indicated that the 14C will likely exist in the oxidized form as CO2 and will contribute slightly to the bulk CO2 concentration of the gas stream, which is airlike in nature (approx. 330 ppMv CO2). The technology under development utilizes the CO2 - Ba(OH)2 8H2O gas-solid reaction with the mode of gas-solid contacting being a fixed bed. The product, BaCO3, possessing excellent thermal and chemical stability, prerequisites for the long-term disposal of nuclear wastes. For optimal process operation, studies have indicated that an operating window of adequate size does exist. When operating within the window, high CO2 removal efficiency (effluent concentrations 99%), and an acceptable pressure drop across the bed (3 kPa/m at 13 cm/s superficial velocity) are possible. This paper will address three areas of experimental investigation. These areas are (1) micro-scale studies on 150-mg samples to provide information concerning surface properties, kinetics, and equilibrium vapor pressures, (2) macro-scale studies on large fixed beds (4.2 kg reactant) to determine the effects of humidity, temperature, and gas flow-rate upon bed pressure drop and CO2 breakthrough, and (3) the design, construction, and initial operation of a pilot unit capable of continuously processing a 34 m3/h (20 ft3/min) air-based gas stream

  12. A novel carbon-14 'solvent-free'-labeling procedure with diethyl malonate

    International Nuclear Information System (INIS)

    A novel labelling procedure for dialkyl malonate preparation under 'solvent-free' conditions in the presence of a phase transfer catalyst was developed. Improved radiochemical yields (about 70%) as compared to the classical preparation routes in DMF are achieved in mere 10 minutes at 130 deg C. General labelling procedures for alkyl bromides are reported. The radiochemical purity by HPLC and analysis conditions using online radioactivity detection are described. The preparation of radiochemicals by this method shows major advantages as regards the purification of the final labelled compound and, since no organic solvent is used, waste management. A simple and easy two-step chromatographic procedure gives rise to pure dialkyl malonates. The method can be especially useful in short-lived isotope labelling

  13. Equipment for a pyrolytic method of detecting tritium and carbon-14 in food

    International Nuclear Information System (INIS)

    The hydrogen isotope tritium is of main interest in food monitoring because of its special property to permeate metallic material and, thus released, commence exchange reactions. The Federal German Food Research Institute (BFE) has issued a manual for monitoring tritium and C-14 in food, and for the analytical method equipment had to be developed allowing user-friendly, semiautomatic testing. In addition, the pyrolytic method for investigation of biological material, a water purification system, and equipment for preparing water samples for comparison form part of the work under review. The main features of the equipment developed are explained along the instructions given in the manual. (orig./PW)

  14. Age determination of ground-waters by means of carbon 14

    International Nuclear Information System (INIS)

    At present the age determination of ground-waters aged between 1,500 and approximately 40,000 years is only possible by measuring their 14C content. A precise age assignment can be established in slightly mineralised waters, whereas it becomes vague in mineralised waters, particularly in acidulous springs. In general, additional information and data are required about the 13C, D, 18O, 3H, 85Kr and the 39Ar contents, about the ph value, temperature and the principal ions. (DG)

  15. Carbon-14 ages of Antarctic meteorites with accelerator and small-volume counting techniques

    International Nuclear Information System (INIS)

    C-14 measurements were made on six Yamato and Victoria Land meteorites using tandem accelerator mass spectroscopy. The studies brought to 27 the number of Antarctic meteorites that have been examined for terrestrial aging. Details of the spectroscopic method are provided, along with the results in combinations with the data from the other 21 meteorites. It is found that the Yamato meteorites are younger than those found at Allan Hills, implying that two mechanisms may exist for the abundant Antarctic meteorites: exposure where falling due to a paucity of ice, and transport and exposure by sublimating ice

  16. Carbon Nanotube and Nanofiber Exposure Assessments: An Analysis of 14 Site Visits.

    Science.gov (United States)

    Dahm, Matthew M; Schubauer-Berigan, Mary K; Evans, Douglas E; Birch, M Eileen; Fernback, Joseph E; Deddens, James A

    2015-07-01

    Recent evidence has suggested the potential for wide-ranging health effects that could result from exposure to carbon nanotubes (CNT) and carbon nanofibers (CNF). In response, the National Institute for Occupational Safety and Health (NIOSH) set a recommended exposure limit (REL) for CNT and CNF: 1 µg m(-3) as an 8-h time weighted average (TWA) of elemental carbon (EC) for the respirable size fraction. The purpose of this study was to conduct an industrywide exposure assessment among US CNT and CNF manufacturers and users. Fourteen total sites were visited to assess exposures to CNT (13 sites) and CNF (1 site). Personal breathing zone (PBZ) and area samples were collected for both the inhalable and respirable mass concentration of EC, using NIOSH Method 5040. Inhalable PBZ samples were collected at nine sites while at the remaining five sites both respirable and inhalable PBZ samples were collected side-by-side. Transmission electron microscopy (TEM) PBZ and area samples were also collected at the inhalable size fraction and analyzed to quantify and size CNT and CNF agglomerate and fibrous exposures. Respirable EC PBZ concentrations ranged from 0.02 to 2.94 µg m(-3) with a geometric mean (GM) of 0.34 µg m(-3) and an 8-h TWA of 0.16 µg m(-3). PBZ samples at the inhalable size fraction for EC ranged from 0.01 to 79.57 µg m(-3) with a GM of 1.21 µg m(-3). PBZ samples analyzed by TEM showed concentrations ranging from 0.0001 to 1.613 CNT or CNF-structures per cm(3) with a GM of 0.008 and an 8-h TWA concentration of 0.003. The most common CNT structure sizes were found to be larger agglomerates in the 2-5 µm range as well as agglomerates >5 µm. A statistically significant correlation was observed between the inhalable samples for the mass of EC and structure counts by TEM (Spearman ρ = 0.39, P 1 μg m(-3). Until more information is known about health effects associated with larger agglomerates, it seems prudent to assess worker exposure to airborne CNT and CNF

  17. Determination of dose coefficients and urinary excretion function for inhalation of carbon-14-labelled benzene

    International Nuclear Information System (INIS)

    Based on existing pharmacokinetic models for benzene, the distribution and retention of activity after inhalation of 14C-labelled benzene in humans were studied. Six different benzene concentrations from 0.1 to 10,000 ppm (corresponding to activity concentrations between 9.6 x 106 and 9.6 x 1011 Bq m-3) and five exposure times from 0.1 to 1000 min were considered. The cumulated activities in the different organs and tissues and the urinary excretion rates were observed to depend non-linearly on the activity intake. The fraction of activity removed via urine varies between 52 and 10% of the intake. Nevertheless, for times that are long compared to the exposure duration the urinary excretion rate is determined by the activity clearance from adipose tissue and thus decreases at a constant rate. This decrease is common for all exposure conditions examined and thus allowed determining a mean urinary excretion rate and corresponding dose coefficients for committed equivalent doses as well as for the effective dose. The uncertainty of the dose coefficients is estimated to be about 50% for the exposure range covered. A 14-day interval for the incorporation monitoring by urine activity counting seems to be reasonable. (author)

  18. Paleo-vegetation study using dating by 14 C and carbon isotope ratio

    International Nuclear Information System (INIS)

    Different approaches that include biological, geomorphological and botanical studies have been used to infer past climatic changes in the Amazon. Our approach involve the use of 13 C analyses in soil organic matter to infer past vegetation changes based on distinct isotopic composition that characterize C3 and C4 plants, and 14 C is used as dating tool, in two regions of natural Forest and Cerrado, located in Rondonia state. The soil at the Forest site is Podzolico Vermelho Amarelo and the Cerrado site is a Latosol Vermelho Amarelo. Radiocarbon analyses of total soil fraction samples indicate that the organic matter in these soils is at least Holocene in age δ13 C values for total soil organic matter in the forest varies from-28 at the surface to 25% at depth of 2 m, indicating the predominance of a C3 cycle in the last 3 270 yrs. At the Cerrado the δ13 C change from -21 to -14% in the first 30 cm characterizing C4 cycle and changed to -19% at 135 cm, probably characterizing a mixture between C3 and C4 plants and an increase to -16% is observed at 195 cm, again indicating a predominance of C4 plants. This data show that the Cerrado ecosystem was much more dynamics in term of vegetation changes than Forest. (author). 10 refs, 2 figs, 1 tab

  19. Automatic counting and recording unit used for dating by the carbon 14 method; Ensemble de comptage et d'impression automatique utilise pour la datation par la methode du carbone 14

    Energy Technology Data Exchange (ETDEWEB)

    Albertinoli, P.; Galliot, J.; Thommeret, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires. Centre Scientifique de Monaco, Monte Carlo

    1969-07-01

    A description is given of the unit used by the 'Centre Scientifique de Monaco' for low-level beta counting and fitted for radioactive dating by the Carbon 14 method. Built entirely by the laboratory in 1964, on the basis of electronic techniques then recent, it has worked without failure since that time. The proportional counter, its high-voltage negative supply, and the counting chains with visual and printing records are detailed by means of 38 figures which reproduce the counter and the electronic circuits. These are contained in two standard 5 U.I structures. The low-voltage power supply of the whole unit is carried out by plus 12 volts and minus 12 volts storage batteries, buffered on a charger connected on the 110 V alternative line. The proportional counter described is filled with CO{sub 2} under one atmosphere pressure and permits the dating of carbonaceous samples with a maximum of 30.000 + 1.000 years (background 3.96 c.p.m. ) within a moderate time (72 hours). (authors) [French] L'ensemble de comptage pour radioactivite beta a bas niveau, destine a la datation par la methode du carbone 14, utilise au Centre Scientifique de Monaco, est decrit. Entierement construit au laboratoire en 1964, sur la base de techniques electroniques alors recentes, il fonctionne depuis cette date sans defaillance. Le compteur proportionnel, son alimentation haute tension negative et les chaines de comptage transistorisees a affichage et impression sont detailles par 38 schemas reproduisant le compteur et les divers circuits electroniques. Ceux-ci sont contenus dans deux chassis standard 5 UI. L'alimentation basse tension de l'ensemble est obtenue par batteries plus 12 et moins 12 volts montees en tampon sur chargeur alimente par le reseau. Le compteur proportionnel decrit, rempli de CO2 sous une atmosphere, permet de dater les echantillons carbones avec un maximum de 30.000 + 1.000 ans (bruit de fond: 3,96 c.p.m. ) en un temps raisonnable (72 heures

  20. The rates of carbon cycling in several soils from AMS14C measurements of fractionated soil organic matter

    International Nuclear Information System (INIS)

    14C mean residence times (MRT) of fractionated organic matter are reported for three pre-bomb soil profiles. Comparisons of organic matter extracted with acid and base showed that the longest MRTs were associated with the non-acid-hydrolysable fraction. The MRT of organic matter in a soil layer represents a combination of the rates of several processes, including decay to CO2 and transport out of the layer. In some instances (notably in the A horizon of the Podzol soil studied in this paper), the MRT is dominated by the rate of transport, rather than the rate of decay. Thus it is important to use the distribution and balance of carbon in the soil profile to assess the meaning of the MRT with respect to influencing atmospheric CO2