Tabassum Nasir

Radiation Doses Due to Indoor Radon Exposure, Before and After the 2005 Earthquake, in Dwellings of Muzaffarabad and the Jhelum Valley, Azad Kashmir, Pakistan

Radiation doses from indoor radon exposure, before and after the 2005 earthquake, have been assessed from measurements taken in the city of Muzaffarabad and Jhelum valley, Azad Kashmir, Pakistan. Indoor radon concentration was measured in dwellings in Muzaffarabad city and the Jhelum valley after the devastating 2005 earthquake using CR-39 based radon box type detectors which were exposed to indoor radon for 60 days. After processing, the observed track densities were related to the indoor radon concentrations using a calibration factor of 0.0092 tracks cm-2 · hr-1 = 1 Bq m-3 of 222 Rn and compared with already published data obtained before the earthquake. The post-earthquake weighted average indoor radon concentration ranged from 65 Bq m-3 to 398 Bq m-3 for the dwellings of state capital city of Azad Kashmir where pre-earthquake values were in the range of 89 Bq m-3 to 167 Bq m-3. In the Jhelum valley, post-earthquake indoor radon concentrations varied from 81 to 509 Bq m-3 and 64 to 456 Bq m-3 in the bedrooms and kitchens, respectively while pre-earthquake radon concentration for Jhelum valley ranges from 86 to 236 Bq m-3 and 62 to 208 Bq m-3 in the bedrooms and kitchens, respectively. The post earthquake indoor radon concentration levels and hence radiation doses have been found higher than those of pre-earthquake values.

Visible light photo catalytic inactivation of bacteria and photo degradation of methylene blue with Ag/TiO2 nanocomposite prepared by a novel method

Water purification is one of the worldwide problem and most of the conventional methods are associated with a number of drawbacks. Therefore it is the need of the day to develop new methods and materials to overcome the problem of water purification. In this research work we present a simple and green approach to synthesize silver decorated titanium dioxide (Ag/TiO2) nanocomposite with an efficient photo catalytic activities. Phytochemicals of the Cestrum nocturnum leaf extract were used to synthesize silver nanoparticles (AgNPs), Titanium dioxide (TiO2) and Ag/TiO2 nanocomposite. To confirm the formation, crystal structure, particle size and shape of green synthesized nanoparticles and nanocomposite, they were characterized by UV-visible spectroscopy (UV-vis), X-ray diffraction spectroscopy (XRD), high resolution transmission electron microscopy (HRTEM), Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). The AgNPs, TiO2 and Ag/TiO2 were evaluated for photo degradation of methylene blue (MB) and photo inhibition of Bacteria. The bio-synthesized Ag/TiO2 nanocomposite was observed to have strong catalytic activities for photo reduction of MB and photo inactivation of bacteria as compared to bare AgNPs and TiO2. In the presence of Ag/TiO2, 90% of MB was degraded only in 40min of irradiation. Alternatively the bare AgNPs and TiO2 degraded less than 30% and 80% respectively of MB even in more than 100min of irradiation. Similarly the Ag/TiO2 has very strong photo inhibition efficiency towards Escherichia coli and Pseudomonas aeruginosa. The zone of inhibition of irradiated Ag/TiO2 nanocomposites against E. coli and P. aeruginosa was 19mm and 17mm respectively which was two times higher than in dark. These promising photocatalytic activities of nanocomposite may be due to the highly decorated AgNPs over the surface of TiO2.

Sapium sebiferum leaf extract mediated synthesis of palladium nanoparticles and in vitro investigation of their bacterial and photocatalytic activities

There is a growing need to introduce eco-friendly and sustainable procedures for the synthesis of metal nanoparticles that include a mild reaction conditions, simple reaction setup, use of nontoxic medium such as water and plant extract, cost effectiveness as well as greater efficiency for biomedical and catalytic applications. For this purpose, small and highly dispersed palladium nanoparticles (PdNPs) were prepared by eco-friendly and cost effective green method using water soluble leaf extract of Sapium sebiferum as a reducing and capping agent. The formation of PdNPs was optimized at various temperatures i.e. (30°C, 60°C and 90°C) and different leaves extract (5mL and 10mL) in order to control their size and shape. The results indicated that PdNPs synthesized at 10mL leaf extract concentration and 60°C temperature have small sized (5nm) and spherical shape. The nanoparticles formation, their dispersion, size and shape were confirmed by various characterization techniques i.e. UV-Vis spectroscopy, Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), thermo gravimetric analysis (TGA) and Dynamic light scattering technique (DLS) analysis. The biologically synthesized PdNPs were tested for size dependent photo degradation of methylene blue and inactivation of bacteria. The PdNPs synthesized at optimized condition (10mL extract concentration and 60°C) have strong photo catalytic activity and reduced 90% methylene blue in 70min. The optimized PdNPs also showed strong bacterial inhibition against Staphylococcus aureus 29(±0.8mm), Bacillus subtilis 19(±0.6mm) and pseudomonas aeruginosa 11(±0.6mm). The results of this examination demonstrate effective applications of extremely active PdNPs.

Monitoring of Indoor Radon Levels Around an Oil Refinery Using CR-39-Based Radon Detectors

Contribution of radon and its decay products towards the total effective dose has been reported to be more than 50% and is a second leading cause of the lung cancer after cigarette smoking. It is an established fact that besides soil and rocks, naturally occurring radio nuclides are also associated with the petroleum extracted from the sedimentary deposits. Therefore, radon measurement around oil refineries is desirable. In this regard, an indoor radon measurement study was carried out in 40 dwellings which were situated in the vicinity of an oil refinery in the Rawalpindi district using CR-39-based radon detectors. For comparison, indoor radon levels were also measured in 40 dwellings situated at a greater distance (>2 km) from the refinery. The maximum measured indoor radon concentration was found to be 190 ± 6 Bq·m−3 whilst the minimum recorded concentration was 12 ± 7 Bq·m−3. The mean radon concentration in the dwellings surveyed was 57 ± 29 Bq·m−3. No significant difference was observed in the average indoor radon levels in the dwellings situated near the oil refinery premises when compared with those further away. From the measured radon concentrations, an annual effective dose was calculated to be 0.9 ± 0.1 mSv which is below the ICRP recommended value.

Assessment of Lung Cancer Risk Using Weighted Average Indoor Radon Levels in Six Districts of the Punjab Province in Pakistan

Year-long measurements of indoor radon concentrations were taken in six districts of the Punjab province, Pakistan, using CR-39-based NRPB radon dosimeters. From the measured indoor radon concentrations, excess lung cancer risk was calculated using the risk model reported in the Biological Effects of Ionising Radiation (BEIR VI) report for the 35—54 and 55—64 year age groups. Using a local occupancy factor, average excess lung cancer risk for the 35—54 y age group residents was found to be 0.66, 0.52 and 0.37 for Gujranwala, Gujrat and Hafizabad districts, respectively. For the Sialkot, Mandibahauddin and Narowal districts it was 0.49, 0.57 and 0.59, respectively. Similarly, for the residents in the 55—64 year age group it was 0.5, 0.40, 0.47, 0.39, 0.46 and 0.46 for Gujranwala, Gujrat, Hafizabad, Sialkot, Mandibahauddin and Narowal districts, respectively. The overall average excess lung cancer risk for the area studied was 0.53.

An overview of radon concentration in Malaysia

Abstract It is known that the inhalation and ingestion of radon gas could lead to the primary health risks for lung and stomach cancers. Besides the health hazards of radon gas, it has different geological applications. In this context, numerous studies have been reported all over the world. Different research groups in Malaysia have also conducted and reported numerous studies since several decades. However, these studies are scattered and need to be compiled for future studies in Malaysia. The main emphasis is to overview and compiles these articles that will work as baseline data for the level of radon gas in Malaysia.

Sequential and double sequential fission observed in heavy ion interaction Of (11.67 MeV/u)197Au projectile with 197Au target

The heavy ion interaction of 11.67 MeV/u 197Au + 197Au has been investigated using mica as a passive detector. By employing Solid State Nuclear Track Detection Technique the data of elastic scattering as well as inelastic reaction channel was collected. The off-line data analysis of multi-pronged events was performed by measuring the three-dimensional geometrical coordinates of correlated tracks on event-by-event basis. Multi-pronged events observed in this reaction were due to sequential and double sequential fission. Using a computer code PRONGY based on the procedure of internal calibration, it was possible to derive quantities like mass transfer, total kinetic energy loss and scattering angles.

Mass Transfer: a Deciding Factor for the Multiplicity of an Event in Deep Inelastic Collisions

Intermediate stage of the three and four-pronged events is investigated in the reaction 208Pb+ 197Au at beam energy 11.67 MeV/u. Multiprong events are analysed numerically using an empirical mass-dependent velocity-range relation. Using the measured three-dimensional coordinates of correlated tracks, it is possible to determine the quantities such as mass transfer and total kinetic energy loss. These quantities are then used to study the intermediate stage of the reaction. It has been observed that mass transfer and total kinetic energy loss at the first step of the reaction decides the multiplicity of an event at the second stage of the sequential fission process.

Inter-relationship of Various Results in Analysis of (14.0 MeV/U) Pb+Pb Reaction Using Mica and CN-85 Track Detectors

Two detector materials mica and cellulose-nitrate(CN)-85 have been used to study (14.0 MeV/u) Pb + Pb reaction. Events of different multiplicities were registered in mica and CN-85 detectors using the 2π-geometry technique of solid state nuclear track detection. After removing the target material from the detectors the damaged trails in the detectors were revealed as tracks by proper chemical etching. The irradiated area of each sample was scanned and events of different multiplicities were traced. The binary events were bifurcated into elastic and inelastic events. The elastic binary events and three prong events, observed in the reaction, have been used to search out coefficients Cμν in the presence of both the detectors, for the reaction under study. Using these coefficients 3- and 4-prong events have been analysed. From the detailed analysis of the results of (14.0 MeV/u) Pb+Pb reaction, obtained from mica and CN-85 track detectors we observed a great resemblance of results obtained from the two detectors. Combining the results of both the detectors, we report some important outcomes.