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T Katona

Publications and source records attributed to T Katona.

9 recordsLinked to original sources
PubMed2005

Development and comparison of five site-specific biosphere models for safety assessment of radioactive waste disposal.

This paper describes the development and application of site-specific biosphere models that might be used for assessment of potential exposures in the framework of performance assessment studies of nuclear waste disposals. Model development follows the Reference Biosphere Methodology that has been set up in the framework of the BIOMASS study. In this paper, the application is to real sites at five European locations for which environmental and agricultural conditions have been described and characterised. For each of the sites a biosphere model has been developed specifically assuming a release of radionuclides to waters that are used by humans, for example as drinking water for humans and cattle and as irrigation water. Among the ingestion pathways, the intakes of drinking water, cereals, leafy vegetables, potatoes, milk, beef and freshwater fish are included in all models. Annual individual doses were calculated, and uncertainties in the results were estimated by means of stochastic calculations. To enable a comparison, all results were normalised to an activity concentration in groundwater of 1 Bq m(-3) for each of the radionuclides considered ((36)Cl, (79)Se, (99)Tc, (129)I, (135)Cs, (226)Ra, (231)Pa, (230)Th, (237)Np, (239)Pu, and (238)U), i.e. those that are usually most relevant in performance assessment studies of nuclear waste disposals. Although the results do not give answers in absolute terms on potential future exposures, they indicate the spectrum of exposures that might occur in different environments and specify the interaction of environmental conditions, human habits and potential exposure.

Animals↗
PubMed2005

A comparative radiological assessment of five European biosphere systems in the context of potential contamination of well water from the hypothetical disposal of radioactive waste.

In the framework of the BioMoSA project for the development of biosphere assessment models for radioactive waste disposal the Reference Biosphere Methodology developed in the IAEA programme BIOMASS was applied to five locations, situated in different European countries. Specific biosphere models were applied to assess the hypothetical contamination of a range of agricultural and environmental pathways and the dose to individuals, following contamination of well water. The results of these site-specific models developed by the different BioMoSA partners, and the individual normalised dose to the exposure groups were compared against each other. Ingestion of drinking water, fruit and vegetables were found to be among the most important pathways for almost all radionuclides. Stochastic calculations revealed that consumption habits, transfer factors, irrigation rates and distribution coefficients (Kd(s)) were the most important parameters that influence the end results. Variations in the confidence intervals were found to be higher for sorbing elements (e.g. (36)Cl, (237)Np, (99)Tc, (238)U, (129)I) than for mobile elements (e.g. (226)Ra, (79)Se, (135)Cs, (231)Pa, (239)Pu). The influence of daughter products, for which the distribution into the biosphere was calculated individually, was also shown to be important. This paper gives a brief overview of the deterministic and stochastic modelling results and the parameter sensitivity. A screening methodology was introduced to identify the most important pathways, simplify a generic biosphere tool and refine the existing models.

Adult↗
PubMed2005

Cost assessment of ventilation and averted dose due to radon in dwellings.

The inhalation dose due to radon and its progenies could be averted by ventilation in dwellings; however, on the other hand the increased ventilation augments the heating cost. Therefore a cost-benefit analysis could contribute to optimise the ventilation rate. In our current work we applied our former defined parameters of the optimising procedure to assess the optimised ventilation and radon concentration in dwellings with average parameters. To assess the inhalation dose rates the time-dependent concentrations of all the progenies were calculated in case of periodic and continuous ventilation as well, at three different radon entry rates (5, 10, 20kBqh(-1)). The optimal ventilation rates in case of continuous ventilation are 0.22, 0.40 and 0.66h(-1), respectively. By these conditions the optimal radon concentration takes 160-210Bqm(-3). According to the more detailed analysis the periodic ventilation gives, in general, a better solution than the continuous one. The Monte Carlo simulations provided a large uncertainty; therefore, before the practical application of the results the uncertainty should be decreased taken into account the local conditions.

Air Pollutants, Radioactive↗
PubMed1999

The use of high-performance size exclusion chromatography (HPSEC) as a molecular weight screening technique for polygalacturonic acid for use in pharmaceutical applications.

Polygalacturonic acid is a linear carbohydrate polymer of monomeric galacturonic acid. It is commercially available as apple and citrus pectins comprised of a mixture of partially methoxylated and/or amidated polygalacturonic acids with molecular weights ranging from 25,000 to > 100,000 Da. Pectin can be chemically or enzymatically hydrolyzed to yield polygalacturonic acid fractions of diverse average molecular weight ranges and polydispersities for a variety of uses. Pectin and polygalacturonic acid are used extensively as gelling agents and stabilizers by the food industry, and have applications as therapeutic, and diagnostic pharmaceutical agents such as the magnetic resonance imaging agent LumenHance. A simple high-performance size exclusion chromatography (HPSEC) method, employing commonly available non-specialized HPLC instrumentation, is described for use as a rapid molecular weight screening technique to determine the average molecular weight range and polydispersity of polygalacturonic acid intended for use in pharmaceutical formulations. A TosoHaas G3000PWXL HPLC column, 50 mM phosphate buffer (pH approximately 6.9) mobile phase, and refractive index detection were used. A molecular weight calibration curve was linear for polysaccharide standards of 180-100,000 Da with a coefficient of correlation of 0.999. The method was employed to screen commercially available polygalacturonic acid raw materials for average molecular weight data (Mn, Mw, and Mp) and polydispersity (Mw/Mn).

Chromatography, High Pressure Liquid↗
PubMed1996

A biomechanical analysis of the stability of titanium bone fixation systems in proximal phalangeal fractures.

Apex bending and torsional loading were utilized to study the effects of different plate design and thickness, and screw size and design on the rigidity and strength of seven different titanium mini- and microplates placed onto osteotomized proximal phalanges. One hundred forty-four fresh frozen human cadaveric proximal phalangeal bones underwent a mid shaft osteotomy followed by application of one of the following plates: (1) Synthes linear 1.5-mm five-hole plates, (2) Leibinger linear 1.2-mm five-hole or (3) 1.7-mm four-hole plates, or (4) Leibinger three-dimensional 1.2-mm four-hole, (5) 1.2-mm eight-hole, (6) 1.7-mm four-hole, or (7) 1.7-mm eight-hole plates. Three-point bending (apex dorsal or apex volar) and torsional loading were utilized for each plating configuration. Analysis of variance models of bone specimen width, depth, cortical thickness, and length revealed that increasing plate thickness was associated with increasing rigidity, but that the three-dimensional design yielded a higher relative rigidity except under apex volar loading.

Biomechanical Phenomena↗
PubMed1995

Physicochemical properties, pharmacokinetics, and biodistribution of gadoteridol injection in rats and dogs.

RATIONALE AND OBJECTIVES: The physicochemical properties of gadoteridol, a macrocyclic nonionic gadolinium complex, were studied together with its pharmacokinetics and biodistribution in rats and dogs. METHODS: Studies in rats were conducted after single intravenous injections at 0.1 or 0.35 mmol/kg using 153Gd-labeled gadoteridol or with seven daily doses of 0.1 mmol/kg to examine the levels of residual gadolinium in organs. Nonradioactive biodistribution and excretion studies were performed in dogs following injection at 0.1 mmol/kg. RESULTS: After injection, the dose was rapidly cleared from rat blood and excreted such that more than 90% of the dose appeared in the urine within 4 hr of injection. At 7 and 14 days postinjection, only extremely low levels of gadolinium were observed in liver and bone; these levels were two to eight times lower than the levels reported after the injection of gadopentetate dimeglumine. CONCLUSION: The extracellular distribution and rapid urinary excretion of gadoteridol is in agreement with data obtained with other gadolinium-containing chelates used as intravascular magnetic resonance imaging contrast agents. Differences observed in the long-term retention of gadolinium between gadoteridol and gadopentetate dimeglumine were consistent with the reported greater in vivo resistance to transmetallation of gadolinium macrocycles compared with the linear gadolinium chelate molecules.

Animals↗
PubMed1995

Comparative biomechanical stability of titanium bone fixation systems in metacarpal fractures.

The biomechanical properties of apex bending and torsional rigidity of 11 different titanium mini- and microplates (Leibinger and Synthes) were examined to evaluate the effects of plate design and thickness and screw size and design. Two hundred sixteen fresh-frozen human cadaveric metacarpal bones underwent a midshaft transverse osteotomy followed by application of one of the following plates: Synthes 1.5-mm and 2.0-mm five-hole linear plates; Leibinger linear 1.2-mm 5-hole, 1.7-mm 4-hole, 2.3-mm 4-hole plates; or Leibinger three-dimensional 1.2-mm 4-hole, 1.2-mm 8-hole, 1.7-mm 4-hole, 1.7-mm 8-hole, 2.3-mm 4-hole, and 2.3-mm 8-hole plates. The specimens were subjected to a three-point bending test with apex dorsal or apex volar loading or torsional loading. Analysis of variance statistical analysis revealed that increasing plate thickness and, more significantly, three-dimensional design were associated with increased rigidity.

Biomechanical Phenomena↗
PubMed1980

Cephalometric VTO.

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Cephalometry↗