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Biomedical subjects

J Planinić

Publications and source records attributed to J Planinić.

11 recordsLinked to original sources
PubMed2005

Radon in the spas of Croatia.

Radon concentrations in air and geothermal water of the spa pools in Croatia were measured and the average values of 40.3 and 4.5 kBq/m3 were obtained, respectively. Great difference between radon concentrations in pool and spring water was considered as a result of mixing normal and geothermal water in the pool as well as the radon decay. Estimation of an effective dose, received by the personnel in the Bizovac spa, gave the value of 0.27 mSv/y. At the location Stubica, the transfer factor of the radon for air and thermal water in the pool was calculated, and the value of 4.9+/-0.7 x 10(-3) was obtained.

Air Pollutants, Radioactive↗
PubMed2004

Radon time variations and deterministic chaos.

Radon concentrations were continuously measured outdoors, in the living room and in the basement at 10 min intervals for a month. Radon time series were analyzed by comparing algorithms to extract phase space dynamical information. The application of fractal methods enabled exploration of the chaotic nature of radon in atmosphere. The computed fractal dimensions, such as the Hurst exponent (H) from the rescaled range analysis, Lyapunov exponent (lambda) and attractor dimension, provided estimates of the degree of chaotic behavior. The obtained low values of the Hurst exponent (0 < H < 0.5) indicated anti-persistent behavior (non-random changes) of the time series, but the positive values of lambda pointed out the grate sensitivity on initial conditions and the deterministic chaos that appeared due to radon time variations. The calculated fractal dimensions of attractors indicated more influencing (meteorological) parameters on radon in the atmosphere.

Air Pollution, Indoor↗
PubMed2001

Temporal variations of radon in soil related to earthquakes.

A radon detector with LR-115 nuclear track film was constructed for radon concentration measurements in soil. Temporal radon variations, as well as the barometric pressure, precipitation and temperature were measured for two years. Negative correlation between radon concentration in soil and barometric pressure was found. For some of the recorded earthquakes that occurred during the observation period, soil radon anomalies may be noticed one month before the quakes.

Croatia↗
PubMed2001

Methodology of radon monitoring and dose estimates in Postojna Cave, Slovenia.

Due to the specific work regime in the Postojna Cave, which depends primarily on the daily number of visitors, and on seasonal variations in air radon concentrations, an optimal methodology for radon and progeny measurement and dose calculation was sought. The program of measurement throughout the years was optimized, and now comprises 3-mo exposures of etched-track detectors, and twice a year, 8-10-d measurements using continuous monitors. Radon concentrations range from about 500 Bq m(-3) in winter to about 6,000 Bq m(-3) in summer, and equilibrium factors range from 0.42 to 0.69 in winter and from 0.33 to 0.86 in summer. Radiation doses from radon decay products for employees in the cave were calculated according to the ICRP 65 methodology. The basic input data are radon concentrations and equilibrium factors at two selected locations in the cave and the records of the time spent by a worker in the cave. Effective doses received by employees annually ranged from 0.02 to 8.4 mSv.

Environmental Exposure↗
PubMed1994

Systematic indoor radon and gamma measurements in kindergartens and play schools in Slovenia.

Systematic measurements of indoor radon concentrations and gamma dose rates were carried out in the 730 kindergartens and play schools in Slovenia that, together, care for 65,600 children. The main method for indoor radon measurement was direct sampling in alpha scintillation cells, but in cases with an increased instantaneous radon concentration, the additional methods of track-etch detectors and alpha spectroscopy were applied. In 528 kindergartens and play schools (72%), radon concentrations were below 100 Bq m-3, with a geometric mean of 58 Bq m-3. In 16 kindergartens and play schools (2.2%), radon concentrations exceeded 800 Bq m-3. In all cases, the main reason for a high indoor radon concentration was the geological structure of the soil. Gamma dose rates were measured with a portable scintillation counter, but in the Ljubljana region thermoluminescence dosimeters were also exposed. The results ranged from 30 to 295 nGy h-1, with a geometric mean of 88 nGy h-1.

Air Pollution, Indoor↗
PubMed1994

Radon level reduction in two kindergartens in Slovenia.

Remedial actions were carried out in two kindergartens with average heating season radon concentrations of about 2,000 Bq m-3. The first kindergarten is built on sedimentary gravel and the second one on fly ash and cinder fill. In both cases, radon accumulated in a sub-floor channel (service tunnel). The channels were opened at both ends. Natural ventilation of the tunnels did not produce a sufficient reduction in radon concentration. A fan was mounted in one kindergarten to ventilate the channel for 20 min three times each day, thus reducing radon levels to an acceptable value.

Air Pollution, Indoor↗
PubMed1993

Thoron activity level and radon measurement by a nuclear track detector.

Radon activity concentrations in the air were measured with LR-115 nuclear track detectors at three locations in Osijek. The respective equilibrium factors and the effective dose equivalents were determined. Indoor concentrations were from 9.8 to 58.2 Bq m-3 and relative errors of the track etching method were near 19 per cent. The indoor alpha potential energy of the radon and thoron progenies was measured with an ISD detector. Independent measurements, performed with a Radhome semiconductor detector, showed that the indoor thoron concentration was nearly 20 per cent of the radon one.

Air Pollutants, Radioactive↗
PubMed1992

222Rn detection efficiency and sensitivity coefficient of the LR 115-II nuclear track detector.

Radon activity concentrations in air were measured by the Kodak-Pathé LR 115-II nuclear track detector. Using the calibrated sensitivity coefficient of the detector (k = 0.0285 Bq-1 m3 tr cm-2 d-1 = 0.33 cm), the critical detection angle was calculated. In the alpha-particle energy region of 1-3.7 MeV, the detector efficiency for 241Am was near 32% but the 222Rn detector efficiency was 23%. The permeability constant of the detector paper filter was measured in a standard radon atmosphere and a value of 9.08 x 10(-6) cm2 s-1 was obtained.

Air Pollution, Radioactive↗
PubMed1980

E.S.R. studies of free radicals derived from reaction of OH with uracil and thymine.

Short-lived free radicals produced in N2O-saturated aqueous solutions of uracil and thymine have been studied using the in situ radiolysis steady-state e.s.r. method. Radical formed in alkaline aqueous solutions by OH addition to either positions C(5) or (6) were observed. Mechanisms for the formation of transient species were derived. The spin density distribution of the unpaired electron was calculated by means of the INDO method.

Chemical Phenomena↗