RESUMO
Measurement of 222Rn is an important research concern because of the high-energy alpha emission of its 218Po and 214Po progeny. The LR-115 passive detector is the basis of a solid-state nuclear track detector (SSNTD) whose use for radon measurements has been well established. The usage of the SSNTD technique requires calibration by comparison. The aim of this work is to evaluate the efficiency calibration parameters for the radon measurement system that three steps: (1) irradiation conditions, (2) etching conditions, and (3) track counting. The following parameters were evaluated: breakdown and counting voltages for the spark counter, detector thickness, etching time, temperature and NaOH concentration as etching conditions for the LR-115 detector. Calibrating factors of 0.035 and 0.028 tracks cm-2 Bq-1 m3 d-1 for the open- and closed-chamber radon monitors, respectively, were determined considering the best efficiency calibration parameter values.
Assuntos
Poluentes Radioativos do Ar/análise , Monitoramento de Radiação/instrumentação , Radiometria/instrumentação , Radônio/análise , Partículas alfa , Calibragem , Polônio/análise , Hidróxido de Sódio/química , Fatores de TempoRESUMO
As part of a program for discovering whether afflicted areas exist, indoor (222)Rn concentrations in the State of Zacatecas were surveyed, (222)Rn concentration being measured by gamma-ray spectrometry of radon decay products adsorbed into charcoal canisters. A survey was implemented during Summer 2001: 228 dwellings in the state were tested by taking mean 254 measurements. Concentrations exhibited a left-skewed distribution of indoor (222)Rn, showing overall average, minimum, and maximum concentrations of 67, 26, and 511 Bqm(-3), respectively. Only seven of the measurements (2.7%) were found equal to or greater than the US EPA action limit (148 Bqm(-3)). Thus, we conclude that the indoor radon environment in Zacatecas State is under US EPA action limit. The few high concentration spots suggest that geological conditions rather than construction materials may be the determinant factor.
Assuntos
Poluição do Ar em Ambientes Fechados/análise , Contaminação Radioativa do Ar/análise , Radônio/análise , Raios gama , México , Análise EspectralRESUMO
The study of natural gamma radioactivity was made to determine the concentrations of natural radionuclides in soil. Twenty soil samples collected in the cities of Zacatecas and Guadalupe and their suburban areas in the Mexican state of Zacatecas were analyzed by gamma-ray spectrometry to determine the activity concentrations of 226Ra, 232Th, and 40K. Gamma-spectrometry measurements were made using a hyperpure germanium detector surrounded with shielding material to reduce the background counting rate. The GammaVision-32 MCA emulation software was used for gamma-ray spectrum analysis and the TRUMP card of 2k as a MCA emulator. Conversion factors were used to calculate the dose to the population from outdoor exposure to terrestrial gamma rays. The measured activity concentration of 226Ra varies from 11 to 38 Bq kg(-1), the activity concentration of 232Th varies from 8 to 38 Bq kg(-1). The activity concentration of 40K is in the range 309-1,049 Bq kg(-1). The overall population mean outdoor terrestrial gamma dose rate is 44.94 nGy h(-1).
Assuntos
Radiação de Fundo , Exposição Ambiental , Raios gama , Solo/análise , Cidades , México , Radioisótopos de Potássio/análise , Doses de Radiação , Radiometria/métodos , Rádio (Elemento)/análise , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Tório/análise , Topografia Médica/métodosRESUMO
Cryptosporidium is a protozoal coccidian parasite that produces among other diseases chronic watery diarrhea. The extent of the diseases is mostly dependent on the immune status of the individual. Mortality in immunosuppressed and AIDS individuals due to the diarrhea illness is nearly 80%. Although no effective treatment is available yet, promising results have been related to the use of Spiramycin, Erythromycin, Somatostatin and its analogues, and zidovudine.