Comparative analysis of radon gas concentration in caves developed in carbonatic, quartzitic and ferruginous lithologies.

Radon gas concentrations in ferruginous, quartzitic/conglomeratic and carbonatic caves were measured and the results obtained in each lithology were compared. Three representatives of each formation (nine caves in total) were studied. The caves are located in three environmental preserved areas in the Ferriferous-Aquifer Quadrangle and in its regional surrounding, in the center-south portion of Minas Gerais State, Brazil. It was found that the average concentration in quartzitic/conglomeratic caves (4,759 Bq/m3) was much higher than those obtained in carbonatic (844 Bq/m3) and ferruginous (945 Bq/m3) caves. This result most likely reflects differences in the uranium content of the rock types. Also, for a better understanding of the radon distribution inside the caves, concentration maps with their interpolated values were generated using geospatial analysis tools.

Radon dosimetry using Solid State Nuclear Track Detectors in different environments: a review.

Radon and its progeny are the major cause of natural radiation emission and its activity concentration is measured by alpha detectors, such as Solid-State Nuclear Track Detector (SSNTD). This work aims to present the applications of CR-39-type SSNTD according to the Natural Radiation Laboratory (LRN) and reports in the literature, aiming to ensure the radioprotection of public and occupationally exposed individuals in indoor and outdoor environments. Therefore, it was reinforced that CR-39 is an important detector for radon radioprotection and dosimetry.

An Assessment of the Potential Use of BNNTs for Boron Neutron Capture Therapy.

Currently, nanostructured compounds have been standing out for their optical, mechanical, and chemical features and for the possibilities of manipulation and regulation of complex biological processes. One of these compounds is boron nitride nanotubes (BNNTs), which are a nanostructured material analog to carbon nanotubes, but formed of nitrogen and boron atoms. BNNTs present high thermal stability along with high chemical inertia. Among biological applications, its biocompatibility, cellular uptake, and functionalization potential can be highlighted, in addition to its eased utilization due to its nanometric size and tumor cell internalization. When it comes to new forms of therapy, we can draw attention to boron neutron capture therapy (BNCT), an experimental radiotherapy characterized by a boron-10 isotope carrier inside the target and a thermal neutron beam focused on it. The activation of the boron-10 atom by a neutron generates a lithium atom, a gamma ray, and an alpha particle, which can be used to destroy tumor tissues. The aim of this work was to use BNNTs as a boron-10 carrier for BNCT and to demonstrate its potential. The nanomaterial was characterized through XRD, FTIR, and SEM. The WST-8 assay was performed to confirm the cell viability of BNNTs. The cells treated with BNNTs were irradiated with the neutron beam of a Triga reactor, and the apoptosis caused by the activation of the BNNTs was measured with a calcein AM/propidium iodide test. The results demonstrate that this nanomaterial is a promising candidate for cancer therapy through BNCT.

Monitoramento da radioatividade alfa relacionada ao radônio-222 em águas de poços da região metropolitana de Curitiba (PR) / Alpha radioactivity monitoring related to radon-222 in water from wells in metropolitan area of Curitiba (PR), Brazil

O objetivo desta pesquisa foi avaliar os níveis de concentração de radônio 222Rn em águas de poços da região metropolitana de Curitiba, Paraná. O trabalho apresenta os resultados das concentrações das medidas feitas em águas de poços da região. As concentrações de 222Rn nas amostras das águas de poços foram medidas por meio do monitor de radônio AlphaGUARD. Os cálculos das concentrações de atividade iniciais de radônio na água foram feitos a partir da curva de decaimento do 222Rn e do equilíbrio secular entre o 222Rn e o 226Ra, observados depois de 30 dias. Os resultados indicaram que cerca de 70% dos valores das concentrações de 222Rn ficaram acima do valor recomendado pela USEPA, de 11,1 Bq.L-1, representando risco radiológico causado por este radionuclídeo. O estudo de caso apresentado mostrou que medidas prévias de radônio são recomendadas para que um projeto de construção seja implementado. No caso em questão, observa-se que as concentrações de radônio diminuem cerca de 56% na primeira caixa d'água e 83% na segunda em relação ao poço. Esse fato mostra que as ações para mitigação de radônio são viáveis e não exigem grandes modificações nos sistemas usuais da construção civil.

This research objective was to assess the level of randon-222 concentration in well water of the metropolitan region of Curitiba, Paraná. Current work presents the results of indoor 222Rn activity ground water samples from artesian wells from aquifers of the region. The studies of radon activity in water were performed using the radon detector AlphaGUARD. The calculations of initial radon activity in water were done considering the 222Rn decay correction as well as equilibrium level of 222Rn and 226Ra observed after 30 days of measurements. Obtained results show that about 70% of measured activity levels of 222Rn are higher than the recommended value of 11.1 Bq.L-1, which represent the risk for the human health associated with this radionuclide. The case study showed that previous measurements of radon are recommended for a construction project is implemented. In this case, it is observed that the radon concentrations decrease about 56% in the first water tank and 83% in the second water tank over the well. This fact shows that the actions for mitigation of radon are viable and do not require major modifications to the usual systems of construction.

13C-urea breath test for the detection of H. pylori infection in children: determination of the cut-off point by a graphic method not depending on the gold standard

Background: validation of 13C-urea breath test (UBT) in children has been troublesome, The aim of the study was to determine the cut-off value of UBT in childhood using a graphic method and not depending on comparison to the gold standard, Methods: Open, prospective study. The authors studied 84 healthy children [44 (52por cento) female, mean age 6 years (min. 8 mo, max. 12y.0)]. UBT (IRIS, Wagner Analysen-Technik, Bremen, Germany) was perfomed using a dose of 50 mg of 13-C-urea for children up to seven years of age and of 75 mg for children older than seven. breath samples were collected before and 25 (T15), 30(T30) and 45 (T45) min after ingestion of the isotope. Mathematical analysis (log transformation for condensation of the results, Gaussian distribution and Ryan-Joiner normality test) and visual graphic analysis were performed for the determination of the cut-off point Results: According to the graphical and mathematical analysis, the cut-off value was determined to be 40/00 DOB (delta over baseline) at T30 and located at more than 3 SD from the mean for the low urease activity group and at 2.94 SD from the mean for the high urease activity group. 22 children (26por cento) were consideres positiv and 62 (74por cento) negative. Conclusion: This siple low-cost methodology can establish a reliable cut-off point for children, with high sensitivity and specificity. The procedure does not require the use of a comparative method or of a gold standard. Moreover, this practical tool can also be used by the laboratories to monitor UBT perfomance over time