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PubMed1994

Immunocytochemistry of carbonic anhydrase and non-radioactive detection of its RNA by in situ hydridization in the chick embryo membranous labyrinth.

An immunocytochemical study was carried out with the aim to localize carbonic anhydrase isozymes (CA I and CA II) in the chick membranous labyrinth. CA I and CA II were localized in the same cells and, during the early developmental stages, were diffusely present in the labyrinthine epithelium. At later stages, the sensorial epithelium of the maculae acusticae, crista ampullaris and papilla basilaris, as well as labyrinthine dark cells and the epithelium of the endolymphatic sac strongly stained by the immunocytochemical procedure. In 1-day and 1-week old chicks, CA was present in the same sites as at advanced embryonal stages. In order to detect mRNA for carbonic anhydrase II, in situ hybridization was also used. Strong hybridization signals were observed in the sensorial epithelium of the saccule, utricle and crista ampullaris, in the tegmentum vasculosum, the endolymphatic sac, the erythrocytes and the choroid plexus in embryos older than 10 days. This positivity persisted until the day after hatching. The authors discuss the significance of labyrinthine CA and, based on in situ hybridization results, suggest that melanocytes do not provide labyrinthine dark cells with enzyme protein.

Animals↗
PubMed1965

The metabolism of glucose by the rabbit lens in the presence and absence of oxygen.

1. The effect of the absence of oxygen on the metabolism of [U-(14)C]glucose by the rabbit lens has been examined. 2. Protein-free extracts of incubated lens were subjected to electrophoresis followed by chromatography on paper; radioautographs showed 10 compounds substantially labelled. In the absence of oxygen, less radioactivity appeared in glucose, sorbitol, fructose, alanine, glutamic acid, glutathione and nucleotides, and more in lactic acid, alpha-glycerophosphate and glycerol. 3. The radioactivity of lens protein was about two to four times greater after aerobic than after anaerobic incubation. 4. The radioactivity of carbon dioxide was 2- to 4-fold greater after aerobic incubation than after anaerobic incubation. 5. After aerobic incubation of the lens, the radioactivity of all the labelled compounds was higher in the outer part (cortex) than in the inner part (nucleus). 6. Free glycerol has been found to be present in the lens. Its concentration, and that of alpha-glycerophosphate, has been measured in the lens of several species of animal.

Alanine↗
PubMed1987

Measurement of 14C emission rates from a pressurised heavy water reactor.

Carbon-14 is produced in pressurised heavy water reactors (PHWR), mainly as an activation product in the fuel. It is also produced in the heavy water used as the primary coolant and moderator, and is produced in the air in the annular space between the pressure tube and calandria tubes as well as in the free space in the calandria vault. The production rates in different systems of a PHWR are calculated on the basis of design parameters. During a period of 3 y, 14C released through the gaseous route has been measured at Rajasthan Atomic Power Station, Kota, India, a PHWR unit. These releases have been found to be mainly 14CO2. This reduced form of 14C is less than 5% of the releases. The normalised releases of 14C have a geometric mean of 5.17 TBq GWe-1 y-1 and a geometric standard deviation of 1.52. The 14C present in the form of carbonates in liquid effluents has also been measured and is 0.14% of the gaseous releases.

Air Pollutants, Radioactive↗
PubMed1971

Thyroxine: convesion to triiodothyronine by isolated perfused rat heart.

Thyroxine labeled with carbon-14 and iodine-125 was perfused through surviving rat hearts. Only when unlabeled triiodothyronine was added as a carrier could the newly formed doubly labeled triiodothyronine be isolated. The fact that this triiodothyronine was labeled with the correct ratio of carbon-14 to iodine-125 indicated that it originated from thyroxine. Approximately 5 percent of the initial carbon-14 radioactivity was found in the recovered triiodothyronine.

Animals↗
PubMed1997

Exempt distribution of a radioactive drug containing one microcurie of carbon-14 urea--NRC. Final rule.

The Nuclear Regulatory Commission (NRC) is amending its regulations to permit NRC licensees to distribute a radioactive drug containing one microcurie of carbon-14 urea to any person for "in vivo" diagnostic use. The NRC has determined that the radioactive component of such a drug in capsule form presents an insignificant radiation risk and, therefore, regulatory control of the drug for radiation safety is not necessary. This amendment makes the drug more widely available and reduces costs to patients, insurers, and the health care industry. This action grants a petition for rulemaking (PRM-35-12) from Tri-Med Specialties, Inc. and completes action on the petition.

Carbon Radioisotopes↗
PubMed1995

Distribution of toxic and radiation components in air particulates.

The concentrations of several toxic heavy metals and volatile organic compounds (VOCs) in various types of Hungarian fly-ash fine particulates were investigated by means of instrumental neutron activation analysis, X-ray fluorescence analysis and gas chromatography, coupled with mass spectrometry. Within a power station, particulate samples were taken from the boiler zone (BO), from the electrostatic dust filter chamber (FI) and from the flue-gas at the top of the stack (ST). Enrichment rates of the toxic metals both in FI and ST particulate fractions related to the BO concentrations were calculated to enable the temperature dependence on the adsorption of the toxic components to be studied. In addition, both the total amounts of the VOCs and their partial distributions in accordance with the number of carbon atoms were also studied in fly-ash particulates. From them, 31 organic species were identified and determined. Since Hungarian brown coals have high uranium and thorium contents, the specific radioactivities of the daughter isotopes of both the 232Th and 238U decay series were also measured and are discussed.

Air Pollutants↗
PubMed1992

Development of a chemical form discrimination system for 14C species in gaseous waste.

A new system was developed for discriminating the chemical form of 14C species in gaseous waste from nuclear facilities. The system consists of an air sample reservoir, a concentration apparatus, a radio-gas chromatograph, and microcomputers. An air sample, which is part of the gaseous effluent released from a stack of a facility, is automatically collected in the tank by trigger signals of stack monitors. After passing the air through a silica gel column, carbon species contained in it are recovered in an activated carbon-supported palladium trap held at -120 degrees C. The recovered species are swept with helium gas and analyzed by the radiogas chromatograph using an activated carbon column and gas-flow counters. Output signals of the gas-flow counters are continuously recorded by the microcomputer. By using this system, the chemical forms of 14C, such as CO, CO2, CH4, C2H4, C2H6, and C3H8 are identified and quantified. A detectable concentration of 0.3 mBq cm-3 for 14CO2 can be obtained. The system has been used to monitor the gaseous waste released from the radioisotope production laboratory and the Japan Research Reactor 2 at Japan Atomic Energy Research Institute.

Air Pollutants, Radioactive↗
PubMed1990

A mathematical model for Rn sampling by activated C adsorption.

This paper describes a diffusion/adsorption model that has been developed for the transport of Rn in an activated carbon porous bed. It is useful in studying the carbon canister Rn sampling technique used for monitoring Rn levels in air. The model calculates the amount of Rn adsorbed by the canister for various situations. The predictions of the response of the canister to both constant, as well as a periodic varying concentration of Rn in the surroundings, compares very well with experimental data. Based on this model, it is possible to simulate on a computer the response of the canister for an arbitrarily varying surrounding Rn level. Such computer simulations are effective tools in the design of a more accurate carbon canister monitor.

Adsorption↗
PubMed2004

Radiological characteristics and investigation of the radioactive equilibrium in the ashes produced in lignite-fired power plants.

Coal- and lignite-fired power plants produce significant amounts of ashes, which are quite often being used as additives in cement and other building materials. In many cases, coal and lignite present high concentrations of naturally occurring radionuclides, such as 238U, 226Ra, 210Pb, 232Th and 40K. During the combustion process, the produced ashes are enriched in the above radionuclides. The different enrichment of the various radionuclides within a radioactive series, such as that of 238U, results in the disturbance of radioactive secular equilibrium. An extensive research project for the determination of the natural radioactivity of lignite and ashes from Greek lignite-fired power plants is in progress in the Nuclear Engineering Department of the National Technical University of Athens (NED-NTUA) since 1983. This paper presents detailed results for the natural radioactivity, the secular radioactive equilibrium disturbance and the radon exhalation rate of the fly-ash collected at the different stages along the emission control system of a lignite-fired power plant as well as of the bottom-ash. From the results obtained so far, it may be concluded that 226Ra radioactivity of fly-ash in some cases exceeds 1 kBq kg(-1), which is much higher than the mean 226Ra radioactivity of surface soils in Greece (25 Bq kg(-1)). Furthermore, the radioactivity of 210Pb in fly-ash may reach 4 kBq kg(-1). These results are interpreted in relation to the physical properties of the investigated nuclides, the temperature in the flue-gas pathway, as well as the fly-ash grain size distribution. It is concluded that towards the coldest parts of the emission control system of the power plant, the radioactivity of some natural nuclides is gradually enhanced, secular radioactive equilibrium is significantly disturbed and the radon exhalation rate tends to increase.

Air Pollutants, Radioactive↗
PubMed1985

Investigations on fly-ash and soil samples in the environment of a coal-fired power plant.

In the main wind direction of a coal-fired power plant dust and soil samples have been collected to analyse the content of fly-ash coming from the power plant. The fly-ash particles are spherical and contain the natural radionuclides mainly Ra-226, Pb-210, Po-210 and K-40 in a higher concentration when compared with the original coal. The investigation of soil samples results in increased Pb-210 and Po-210 concentrations when compared with the natural environment. By presence of spherical particles in dust and soil samples the power plant can be identified as the emitter.

Air Pollutants↗
PubMed2005

Investigation of occupational radiation exposures to NORM at an Irish peat-fired power station and potential use of peat fly ash by the construction industry.

Annually, approximately 15% of Ireland's electricity requirement is provided through the combustion of 3 x 10(6) tonnes of peat. While the literature on coal-fired power generation is quite abundant, studies on the peat-fired power generation industry from a radiological point of view are scarce. A study of the largest Irish peat-fired power plant was initiated to review the potential occupational radiation exposures arising from the occurrence of naturally occurring radioactive material (NORM) at different stages of the industrial process and to investigate any radiological health consequences that may arise should peat fly ash be used as a component of building materials. Ambient gamma dose rate measurements, radon measurements, quantification of the occupational exposure from inhalation of airborne particles (personal air sampling) and gamma spectrometry analysis of peat, peat ash and effluent samples from the ash ponds were undertaken. The results indicate that the radiation dose received by any worker involved in the processing of the peat and the handling of the ash resulting from peat combustion does not exceed 150 microSv per annum. Regulatory control of the peat-fired power generation is therefore unnecessary according to the Irish legislation with regards to NORM. The potential use of peat fly ash as a by-product in the building industry was also found to have a negligible radiological impact for construction workers and for members of the public.

Air Pollutants, Radioactive↗
PubMed1985

Carbon-14 discharge at three light-water reactors.

A long-term-sampling evaluation was made of the quantity, discharge pathway, and chemical form of 14C released from 2 pressurized water reactors (PWR) and 1 boiling water reactor (BWR) in the northeastern United States. For the R. E. Ginna PWR the discharge rate of gaseous 14C was 11.6 Ci/GW(e)-yr. Venting of gas decay tanks accounted for 42%, while 35% was discharged through auxiliary building ventilation and 23% through containment venting. The average chemical composition was 10% as 14CO2, 90% as 14CH4 and other hydrocarbon gases. For the Indian Point Unit 3 PWR, the discharge rate was 9.6 Ci/GW(e)-yr, primarily by pressure-relief venting and purging of the containment air. Venting of gas decay tanks accounted for about 7% of the total released. The chemical species were 26% 14CO2, 74% 14CH4 and other hydrocarbon gases. For the J. A. FitzPatrick BWR, the discharge rate was 12.4 Ci/GW(e)-yr. Approximately 97% of the release was via off-gas discharge, which was about 95% 14CO2. For all 3 reactors the quantity of 14C released with liquid and solid wastes was less than 5% of the gaseous release.

Air Pollutants↗