The influence of meteorological parameters on indoor radon in selected traditional Kenyan dwellings.

The effects of outdoor temperature, rainfall and wind speed on the indoor radon concentration in four types of traditional hut in Kenya were investigated by performing short-term (about 48 h) measurements with activated charcoal canisters. The concentrations vary widely (30.2-315.4 Bq m(-3)) during the study period, and the overall mean is 170.3 +/- 39.6 Bq m(-3). The indoor radon concentration correlates negatively with both the outdoor temperature (R(2) = 0.06) and the wind speed (R(2) = 0.11) but positively with rainfall (R(2) = 0.03). The results showed that changes in meteorological parameters cause more variations in indoor radon concentrations than the differences in the buildings' characteristics (i.e., designs, materials, etc). However, these variations are not significant (at 1% significance level).

Charge transport mechanism in thin cuticles holding nandi flame seeds.

Metal-sample-metal sandwich configuration has been used to investigate DC conductivity in 4 mum thick Nandi flame [Spathodea campanulata P. Beauv.] seed cuticles. J-V characteristics showed ohmic conduction at low fields and space charge limited current at high fields. Charge mobility in ohmic region was 4.06 x 10(-5) (m(2)V(-1)s(-1)). Temperature-dependent conductivity measurements have been carried out in the temperature range 320 K < T > 450 K. Activation energy within a temperature of 320 K-440 K was about 0.86 eV. Variable range hopping (VRH) is the main current transport mechanism at the range of 330-440 K. The VRH mechanism was analyzed based on Mott theory and the Mott parameters: density of localized states near the Fermi-level N(E(F)) approximately 9.04 x 10(19) (eV(-1)cm(-3)) and hopping distance R approximately 1.44 x 10(-7) cm, while the hopping energy (W) was in the range of 0.72 eV-0.98 eV.

An investigation of the repeatability of calibration factors in gamma-ray spectrometry of geological materials.

A NaI(Tl)-based gamma spectrometer for the analysis of geological materials was calibrated using the IAEA reference materials RGU-1, RGTH-1 and RGK-1. To simulate typical geological samples, two additional standards were prepared from aliquots of the three reference materials. The reproducibility of the instrument calibration factors (CFs) was tested by repeated measurements of the pure IAEA reference materials and the mixed samples in a reproducible counting geometry. The results were analysed using a two-way classification analysis of variance; it was found that the variance in the CFs is significantly higher between standards than it is between measurements. Allowance should be made for this when estimating uncertainties in measurements with the NaI(Tl) spectrometers.