Effect of dimerization on the field-induced birefringence in ferrofluids

The magnetic-field-induced birefringence in a ferrofluid composed of spherical cobalt nanoparticles has been studied both experimentally and theoretically. The considerable induced birefringence determined experimentally has been attributed to the formation of chains of nanoparticles. The birefringence has been measured as a function of the external magnetic field and the volume fraction (f) of nanoparticles. It is quadratic in f as opposed to the Faraday effect, which is linear in f. Experimental results agree well with the theoretical model based on a simple density functional approach. For dilute solutions the experimental results can be explained by assuming that only dimers of nanoparticles are formed while the concentration of longer chains is negligible

Geochemical and geophysical monitoring of thermal waters in Sloveniain relation to seismic activity

Pre-seismic related strains in the Earth s crust are the main cause of the observed geophysical and geochemical
 anomalies in ground waters preceding an earthquake. Posoc?je Region, situated along the Soc?a River, is one of
 the most seismically active areas of Slovenia. Our measuring stations close to the Posoc?je Region were installed
 in the thermal springs at Bled in 1998 and at Zatolmin in 1999. Since the beginning of our survey, radon concentration,
 electrical conductivity and water temperature have been measured continuously once every hour. In
 May 2002, the number of geochemical parameters monitored was extended to ionic concentration, pH and Eh,
 which are analysed once a month. Before seeking a correlation between geochemical and geophysical anomalies
 with seismic events, the influence of meteorological (atmospheric precipitation, barometric pressure) and hydrological
 (water table of the Tolminka River) factors on observed anomalies were studied. Results at Zatolmin
 showed that some radon variation during the period from June to October 2002 may be related to seismic activity
 and not only to meteorological effects

Geochemical and geophysical monitoring of thermal waters in Sloveniain relation to seismic activity

Pre-seismic related strains in the Earth s crust are the main cause of the observed geophysical and geochemical anomalies in ground waters preceding an earthquake. Posoc?je Region, situated along the Soc?a River, is one of the most seismically active areas of Slovenia. Our measuring stations close to the Posoc?je Region were installed in the thermal springs at Bled in 1998 and at Zatolmin in 1999. Since the beginning of our survey, radon concentration, electrical conductivity and water temperature have been measured continuously once every hour. In May 2002, the number of geochemical parameters monitored was extended to ionic concentration, pH and Eh, which are analysed once a month. Before seeking a correlation between geochemical and geophysical anomalies with seismic events, the influence of meteorological (atmospheric precipitation, barometric pressure) and hydrological (water table of the Tolminka River) factors on observed anomalies were studied. Results at Zatolmin showed that some radon variation during the period from June to October 2002 may be related to seismic activity and not only to meteorological effects

Thoron emanation and exhalation of Slovenian soils determined by a PIC detector-equipped radon monitor

The health risk from thoron (Rn-220) is usually ignored owing to its short half-life (55.6 s), but the generated thoron decay products can cause a significant dose contribution. In this study, altogether 51 Slovenian soil samples were investigated using an accumulation chamber technique to obtain information about thoron exhalation features. The obtained (massic) thoron exhalation results varied between 6.9 and 149 mBq•kg–1•s–1 (average: 55.2 mBq•kg –1•s–1). The Th-232 content was determined using HPGe gamma spectrometry. The Th-232 activity concentration ranged between 9.3 and 161.7 Bq•kg–1 (average: 64.6 Bq•kg –1). The thoron emanation features were also calculated from the obtained results (2.9 to 21.2% with an average of 8.6%). The thoron exhalation and emanation properties were compared with the radon exhalation and emanation features determined in a previous study. It was found that there was no correlation between the radon and thoron emanation features, according to the obtained data. This can be explained by the different Ra-224 and Ra-226 distributions in the soil grains. As a result, the thoron emanation factor cannot be predicted from radon emanation and vice versa

Thoron emanation and exhalation of Slovenian soils determined by a PIC detector-equipped radon monitor

The health risk from thoron (Rn-220) is usually ignored owing to its short half-life (55.6 s), but the generated thoron decay products can cause a significant dose contribution. In this study, altogether 51 Slovenian soil samples were investigated using an accumulation chamber technique to obtain information about thoron exhalation features. The obtained (massic) thoron exhalation results varied between 6.9 and 149 mBq•kg–1•s–1 (average: 55.2 mBq•kg –1•s–1). The Th-232 content was determined using HPGe gamma spectrometry. The Th-232 activity concentration ranged between 9.3 and 161.7 Bq•kg–1 (average: 64.6 Bq•kg –1). The thoron emanation features were also calculated from the obtained results (2.9 to 21.2% with an average of 8.6%). The thoron exhalation and emanation properties were compared with the radon exhalation and emanation features determined in a previous study. It was found that there was no correlation between the radon and thoron emanation features, according to the obtained data. This can be explained by the different Ra-224 and Ra-226 distributions in the soil grains. As a result, the thoron emanation factor cannot be predicted from radon emanation and vice versa

Geochemical monitoring of thermal waters in Slovenia: relationships to seismic activity

Thermally anomalous fluids released in seismic areas in Slovenia were the subjects of geochemical monitoring. Thermal waters were surveyed from the seismically active area of Poso$cje (Bled and Zatolmin; NW Slovenia) and from Rogaska Slatina in eastern Slovenia. Continuous monitoring of geochemical parameters (radon concentration, electrical conductivity, and water temperature) was performed with discrete gas sampling for their 3He/4He ratio. The observed values were correlated with meteorological parameters (rainfall, barometric pressure and air temperature) and with seismic activity. Only a few earthquakes occurred in the vicinity of the measuring sites during the monitoring period. Nevertheless, changes in radon concentration, water temperature, electrical conductivity and helium isotopic ratio were detected at the three thermal springs in the periods preceding the earthquakes. A close correlation was also observed of both water temperature and electrical conductivity with the Earth tide, making the observations in the selected sites a promising tool for addressing the widely debated question of earthquake prediction.Ministry of Education,Science and Sport of SloveniaPublished919–930partially_ope

Geochemical monitoring of thermal waters in Slovenia: relationships to seismic activity

Thermally anomalous fluids released in seismic areas in Slovenia were the subjects of geochemical monitoring. Thermal waters were surveyed from the seismically active area of Poso$cje (Bled and Zatolmin; NW Slovenia) and from Rogaska Slatina in eastern Slovenia. Continuous monitoring of geochemical parameters (radon concentration, electrical conductivity, and water temperature) was performed with discrete gas sampling for their 3He/4He ratio. The observed values were correlated with meteorological parameters (rainfall, barometric pressure and air temperature) and with seismic activity. Only a few earthquakes occurred in the vicinity of the measuring sites during the monitoring period. Nevertheless, changes in radon concentration, water temperature, electrical conductivity and helium isotopic ratio were detected at the three thermal springs in the periods preceding the earthquakes. A close correlation was also observed of both water temperature and electrical conductivity with the Earth tide, making the observations in the selected sites a promising tool for addressing the widely debated question of earthquake prediction