Wyniki wyszukiwania - Biblioteka Nauki

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Radiocarbon 14C method as useful tool for flue gas monitoring application: review

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Stachów M.

Budownictwo i Inżynieria Środowiska

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2016

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tom Vol. 7, no. 4

247--251

EN

Cosmic-ray research which started just after the second world war in 1947, encouraged widespread use of radioactive particles in many areas of science and technology, starting from astronomy, chemistry, archaeology, biology, botany, medicine and lately ending with environmental studies. Method based on measurements of the radioactive elements remains in various samples (solid, liquid and gaseous) can be very useful tool for ecological and environmental analytical measurements. The 14C liquid scintillating counting method was used for simplified determination of the biomass content in flue gas from combustion processes or in the finished bio-product. Review of the latest results and progress in this research area shows the growth of interest from industrial sector in normalised method for biomass content determination.

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Preliminary evaluation of14C and36Cl in nuclear waste from Ignalina Nuclear Power Plant decommissioning

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Mažeika J. , Lujanienė G. , Petrošius R. , Oryšaka N. , Ovčinikov S.

Open Chemistry

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2015

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tom 13

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nr 1

EN

On a first attempt, the determination of 14C and 36Cl activity concentrations in basic operational waste (spent ion-exchange resins and perlite mixture), in decommissioning waste (construction concrete, sand, stainless steel and serpentinite) and irradiated graphite from the Ignalina NPP has been performed. The samples for measurement of the specific activity of 14C and 36Cl were obtained from the selected places, where the highest values of the dose rate and the activity concentrations of gamma emitters were found. The performed study of the total 14C and 36Cl activity concentrations was based on estimated chemical forms of 14C (inorganic and organic compounds) and 36Cl as Cl- ion. The tested methods used in this study were found to be suitable for estimation of activity concentrations of measured radionuclides.

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Investigation of CO2 Capture Property of CaO Sorbent in Various Molten Chloride Media with Different Operation Temperature

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Kim S.-W. , Jeon M. K. , Lee K.

Archives of Metallurgy and Materials

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2020

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tom Vol. 65, iss. 3

1051--1055

EN

CaO sorbent dissolved in chloride molten salts was investigated to identify its CO2 capture property. Various molten salt systems with different melting points (CaCl2 , LiCl, LiCl-CaCl2 , and LiCl-KCl) were used to control the operation temperature from 450 to 850ºC in order to determine the effect of the operation temperature on the chemical reaction between CaO and CO2 . The CaO sorbent showed the best performance at 550ºC in the LiCl-CaCl2 molten salt (conversion ratio of 85.25%). This temperature is lower than typical operation temperature of the solid-state CaO sorbent (~700ºC).

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A multi-layer box model of carbon dynamics in soil

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Kuc T.

Nukleonika

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2005

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tom Vol. 50, nr 2

49-55

EN

Abstract A multi-layer box model (MLB) for quantification of carbon fluxes between soil and atmosphere has been developed. In the model, soil carbon reservoir is represented by two boxes: fast decomposition box (FDB) and slow decomposition box (SDB), characterised by substantially different turnover time (TT) of carbon compounds. Each box has an internal structure (sub-compartments) accounting for carbon deposited in consecutive time intervals. The rate of decomposition of carbon compounds in each sub-compartment is proportional to the carbon content. With the aid of the MLB model and the 14C signature of carbon dioxide, the fluxes entering and leaving the boxes, turnover time of carbon in each box, and the ratio of mass of carbon in the slow and fast box (Ms/Mf) were calculated. The MBL model yields the turnover time of carbon in the FDB (TTf) ca. 14 for typical investigated soils of temperate climate ecosystems. The calculated contribution of the CO2 flux originating from the slow box (Fs) to the total CO2 flux into the atmosphere ranges from 12% to 22%. These values are in agreement with experimental observations at different locations. Assuming that the input flux of carbon (Fin) to the soil system is doubled within the period of 100 years, the soil buffering capacity for excess carbon predicted by the MLB model for typical soil parameters may vary in the range between 26% and 52%. The highest values are obtained for soils characterised by long TTf, and well developed old carbon pool.

5

Isotope analyses of the lake sediments in the Plitvice Lakes, Croatia

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Horvatinčić N. , Sironić A. , Barešić J. , Bronić I. , Nikolov J. , Todorović N. , Hansman J. , Krmar M.

Open Physics

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2014

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tom 12

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nr 10

707-713

EN

The analyses of radioactive isotopes 14C, 137Cs and 210Pb, and stable isotope 13C were performed in the sediment cores, top 40 cm, taken in 2011 from karst lakes Prošće and Kozjak in the Plitvice Lakes National Park, central Croatia. Frozen sediment cores were cut into 1 cm thick layers and dried. 14C activity in both carbonate and organic fractions was measured using accelerator mass spectrometry technique with graphite synthesis. 137Cs, 210Pb, 214Pb and 214Bi were measured by low level gamma spectrometry method on ORTECHPGe detector with the efficiency of 32%. Distribution of 14C activity from both lakes showed increase of the 14C activity in the top 10–12 cm in both carbonate and organic fractions as a response to thermonuclear bomb-produced 14C in the atmosphere in the sixties of the 20th century. Anthropogenically produced 137Cs was also observed in sediment profiles. Sedimentation rates for both lake sediments were estimated based on the unsupported 210Pb activity. Different 14C activity of the carbonate fraction (63–80 pMC, percent of modern carbon) and organic fraction (82–93 pMC) is the result of geochemical and biological processes of the sediment precipitation in the lake waters. This is also confirmed by the δ 13 C values of both fractions. Carbon isotope composition, a 14 C and δ 13 C, was compared with the lake sediments from the same lakes collected in 1989 and 2003.

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Holocene sediments of the Ustka Cliff (Northern Poland) in view of radiometric dating

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Wróblewski R. , Fedorowicz S. , Kamieńska K.

Geochronometria

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2013

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tom Vol. 40, no. 3

187--194

EN

The cliff in Ustka is an active one. The area is one of the most eroded sea shores of the Polish coast. The Ustka Cliff mainly consists of Holocene sandy deposits, but its basis is built of gla-cial till and clay. Field search allowed to recognize the structure and sedimentary conditions of Holo-cene deposits exposed in the cliff. A comparison of dating results obtained for fossil soils and peat as well as aeolian deposits, using 14C and TL methods, respectively, with available literature records is presented. The evaluation of results obtained allowed to define three main dune-forming phases for the first time for this part of the Polish coast. During the research studies new data on the processes and environmental conditions was gained and the development of structure of the area during the last 10 thousand years was reconstructed. The analysis of available data from other sections of the south-ern Baltic coast shows that results obtained are age similar to those determined for the Łeba Spit. The research is part of a project concerning the geomorphology of the Ustka Bay.

7

Differentiation between fossil and biofuels by liquid scintillation beta spectrometry - direct method

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Edler R. , Kaihola L.

Nukleonika

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2010

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tom Vol. 55, No. 1

127-131

EN

Liquid scintillation spectrometry of 14C in gasoline/ethanol and diesel oil was carried out using QuantulusŽ and straight mixtures of fuel and an organic scintillation cocktail. A linear correlation was found between the concentration of carbon that originates from the bioethanol (biocarbon) and the fuel mixture’s 14C activity in the range 0–100% (m/m) bioethanol content. Because of these good linear correlations, quantitative determination of a fuel’s biocarbon content can be made by 14C analysis. The direct method is also applicable to analysis of the bio-based materials dissolvable in solvents, which can be mixed with scintillation cocktails.

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Effect of liquid scintillating cocktail volume on 3H and 14C measurement parameters using a Quantulus spectrometer

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Komosa A. , Ślepecka K.

Nukleonika

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2010

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tom Vol. 55, No. 2

155-161

EN

Results of study on the influence of cocktail volume on such measuring parameters as counting efficiency, standard quench parameter (SQP) and figure of merit (FOM) are described. Nine commercial cocktails were tested using a Quantulus spectrometer. Two kinds of vials (low-diffusion teflon-coated polyethylene (LD-PE) and high-performance glass (HP-G)) and two standard solutions (14C and 3H) were used. Measurements were performed at seven quench levels ensured by carbon tetrachloride addition to the scintillation vials. Various quench sensitivity of the studied cocktails was found. Cocktails based on simple benzene-derived solvents revealed the best quench resistance. In general, increasing cocktail volume caused an increase in the counting efficiency. However, the background increased as well, what resulted in FOM diminishing. Studied cocktails revealed also various responses to volume changes.

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Could an anomaly in Turin Shroud blood reopen the 1988-radiocarbon-dating result?

85%

Fanti G.

World Scientific News

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2021

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tom 162

102-119

EN

This work proposes an explanation for a blood anomaly found in the Turin Shroud (TS). Unlike common human blood which contains significant levels of nitrogen (weight percentages of the order of 10%), TS blood shows levels of nitrogen which are lower than the background noise produced by the measuring instrument (about 1%). It is not easy to find an explanation for this result, but if we refer to the hypothesis formulated by T.J. Phillips who first proposed that neutron radiation had acted on the TS and therefore on the blood analyzed, it is possible to qualitatively understand what may have altered the observed nitrogen levels. The hypothesis of T.J. Phillips proposes that neutrons would have irradiated the TS, changing some of the nitrogen nuclei to different isotopes. In particular, it would have caused nitrogen atoms to be transformed into 14C and so the results of the radiocarbon dating of the TS performed in 1988 would have to be corrected to allow for the corresponding systematic effect hypothesized in that paper.