The effect of air mass origin on the ambient concentrations of ⁷Be and ²¹⁰Pb in Islamabad, Pakistan

Concentration of radionuclides ²¹⁰Pb and ⁷Be, having half lives of 22.3 years and 53.29 days, respectively, in the surface air samples of Islamabad (33.38°N, 73.10°E and Altitude ∼536 m asl.) are measured. The non-destructive technique of gamma-spectrometry, with a high purity germanium HPGe detector, was employed for the analysis of all samples. The annual average concentrations of ²¹⁰Pb and ⁷Be in the surface air samples were determined as 0.284 ± 0.15 and 3.171 ± 1.14 mBq m⁻³, respectively. Our results have shown a seasonal variation of the concentration of ⁷Be in air samples with high values for the spring season. High concentrations for ²¹⁰Pb are obtained when air masses originate from plain areas of Pothohar region, located in the South-West, West and North West of Islamabad. Our values of concentrations show a nice agreement with the relevant reported results.

Estimation of mean annual effective dose through radon concentration in the water and indoor air of Islamabad and Murree

Different samples of water, indoor air and soil gas have been collected from Islamabad (33 degrees 38'N, 73 degrees 09'E, altitude of 1760 ft.), the capital of Pakistan and Murree (33 degrees 53'N, 73 degrees 23'E, altitude of 7323 ft.), lying on a geological fault line and are analysed for the estimation of mean effective dose through radon concentrations by using RAD-7, a solid state alpha-detector. The variation of radon concentration in water, indoor air and soil gas in Islamabad region ranges from 25.90-158.40 kBq m(-3), 43.26-97.04 Bq m(-3) and 17.34-72.52 kBq m(-3), having mean values 88.63 kBq m(-3), 70.67 Bq m(-3) and 45.08 kBq m(-3)(,) respectively. It ranges from 1.64-10.20 kBq m(-3), 18.48-42.08 Bq m(-3) and 0.61-3.89 kBq m(-3) with mean values 4.38 kBq m(-3), 28.63 Bq m(-3) and 1.70 kBq m(-3)(,) respectively in Murree and its surroundings. The total mean annual effective doses from water and indoor air of Islamabad and Murree regions are 2.023 and 0.733 mSv a(-1), respectively. These doses are within the recommended limits of the world organisations.

Radon monitoring in water sources of Balakot and Mansehra cities lying on a geological fault line

This paper relates to a series of systematic studies regarding measurement of radon concentration in the earthquake-affected areas of northern Pakistan. Radon is a radioactive alpha-particle-emitting gas originating from the decay series of uranium and thorium and is found anywhere in soil, air and water. The nature of water does not matter with regard to the presence of radon, however, the level of radon concentration varies in different types of water. The present survey is carried out in water samples from the fault zone of Balakot and Mansehra regions, North West Frontier Province, Pakistan, which is important for geological consideration and protection from radiation hazards. The measurements were made on a Pylon system that is based on the radon gas measurement with a Lucas cell. In 72 water samples in the equilibrium state between radon and its progeny, the concentration level of radon is measured. The results show that the radon concentrations are in the range of 4.99-24.52 kBq/m(3), with an average value of 15.52 kBq/m(3) for all types of water taken in this survey.

Tuning the characteristics of electrochemically fabricated gold nanowires

We have developed different electrochemical procedures for the production of gold nanowires with variable and controllable crystallographic and morphological properties using etched ion track templates. The texture of the nanowires is tuned by the variation of the electrodeposition parameters. Potentiostatic plating at low overvoltage provides strongly (110) textured wires for diameters below 100 nm. With the increase in diameter above 100 nm, this texture decreases and the signal from ({111} planes becomes more pronounced. Under reverse pulse deposition conditions, (100) textured wires are generated. The growth mechanism is discussed in detail in terms of the surface energy minimum principle. In addition, wires are shaped in a reliable way from cylindrical to conical geometry by engineering the pore structure in the template.

Use of track detectors in biomedical sciences

The CR-39 track detectors have been applied to irradiate the Chinese hamster V79-753B cells for survival studies. The survival curves have given satisfactory results. Energies of the incoming as well as outgoing proton beams evaluated from the track diameters are found to be close to the values found separately by surface barrier detector (SSBD).