Terrestrial gamma dose rate in Pahang state Malaysia

Environmental terrestrial gamma radiations (TGR) were measured in Pahang state Malaysia between January and April 2013. The TGR dose rates ranged from 26 to 750 nGy h^?1. The measurements were done based on geology and soil types of the area. The mean TGR dose rate was found to be 176 ± 5 nGy h^?1. Few areas of relatively enhanced activity were located in Raub, Temerloh, Bentong and Rompin districts. These areas have external gamma dose rates of between 500 and 750 nGy h^?1. An Isodose map of the state was produced using ArcGIS9 software version 9.3. To evaluate the radiological hazard due to terrestrial gamma dose, the annual effective dose equivalent and the mean population weighted dose rate were calculated and found to be 0.22 mSv year^?1 and 168 nGy h^?1 respectively.     

Assessment of terrestrial gamma radiation dose rate (TGRD) of Kelantan State,Malaysia: Relationship between the geological formation and soil type to radiation dose rate

Terrestrial gamma radiation dose rates (TGRD) of Kelantan State were measured in situ using a portable [NaI(TI)] micro roentgen (µR) survey meter. The TGRD rates ranged between 44 and 500 nGy h^?1 with a mean value of 209 ± 8 nGy h^?1. The distribution of these measurements in various districts of the state shows the statistically the influence of geology and soil types on the dose rate values. The data obtained could be used in formulating safety standard and radiological guidelines.     

Effect of dose and dose rate of gamma radiation on catalytic activity of catalase

Catalytic activity of gamma irradiated catalase from bovine liver was studied for hydrogen peroxide decomposition at constant temperature and pressure. The measurement was performed at temperatures 27, 32, 37, 42 and 47 °C. Solutions containing 1 and 0.01 g dm⁻³ of catalase in phosphate buffer were used for the study. Repeatability of both sample preparation and kinetics measurement was experimentally verified. Rate constants of the reaction were determined for all temperatures and the activation energy was evaluated from Arrhenius plot. Gamma irradiation was performed using ⁶⁰Co radionuclide source Gammacell 220 at two different dose rates 5.5 and 70 Gy h⁻¹, with doses ranging from 10 to 1000 Gy. The observed reaction of irradiated and non-irradiated catalase with hydrogen peroxide is of the first order. Irradiation significantly decreases catalytic activity of catalase, but the activation energy does not depend markedly on the dose. The effect of irradiation is more significant at higher dose rate.     

Distribution patterns of gamma radiation dose rate in the high background radiation area of Odisha,India

Journal of Radioanalytical and Nuclear Chemistry - Absorbed dose rates in air for 20 residential areas in Odisha were measured using a vehicle-mounted NaI(Tl) scintillation spectrometer. The...     

Evaluation of natural gamma radiation and absorbed gamma dose in soil and rocks of Perambalur district (Tamil Nadu,India)

The activity concentrations and absorbed gamma dose of primordial radionuclides ²³⁸U, ²³²Th and ⁴⁰K were determined employing γ-ray spectrometry in 31 soil samples from the land area earmarked for house construction in Perambalur district and 14 rock samples from quarries that supply stones for the entire district. The soil samples registered relatively a higher mean value of 13.2 Bq kg^?1 for ²³⁸U, 66 Bq kg^?1 for ²³²Th and 340.3 Bq kg^?1 for ⁴⁰K as compared to mean values for rock samples (²³⁸U—8.0 Bq kg^?1; ²³²Th—65.1 Bq kg^?1; ⁴⁰K—199.1 Bq kg^?1). The mean absorbed gamma dose rate for soil (61.4 nGy h^?1) marginally exceeded the prescribed limit of 55 nGy h^?1 while, rocks registered the mean absorbed gamma dose rate of 10.4 nGy h^?1. The mean radium equivalent activity was distinctly higher in soil (130.6 Bq kg^?1) than in rock (20.0 Bq kg^?1). However, these values were lower than the limit (370 Bq kg^?1) set by OECD for building materials. It is evident from the data that the soil and rocks do not pose any radiological risk for house constructions in Perambalur district.     

Monitoring of anthropogenic and natural radionuclides and gamma absorbed dose rates in eastern Anatolia

The distribution of the anthropogenic (¹³⁴Cs and ¹³⁷Cs) and natural (²³⁸U, ²³²Th and ⁴⁰K) radionuclide concentrations were studied in soil, foodstuff and bioindicator samples collected from the near site of the Medzamor Nuclear Power Plant at the border of eastern Anatolia of Turkey. For some time, the gross-a and b-concentrations were also determined in the water samples of the region and the absorbed dose rates in air at 1 m above ground were measured. The results showed no additional artificial contamination from the Medzamor Nuclear Power Plant before June 1996.     

CCRI supplementary comparison of standards for absorbed dose to water in 60Co gamma radiation at radiation processing dose levels

Six national standards for absorbed dose to water in ⁶⁰Co gamma radiation at the dose levels used in radiation processing have been compared over the range from 5 to 30 kGy using the alanine dosimeters of the NIST and the NPL as the transfer dosimeters. The standards are in agreement at the level of around 0.5%, which is significantly smaller than the stated standard uncertainties.     

Radioactivity of building materials in Serbia and assessment of radiological hazard of gamma radiation and radon exhalation

Journal of Radioanalytical and Nuclear Chemistry - This paper presents a gamma spectrometric analysis of 47 samples of building materials produced and used in Serbia. Based on the measured activity...     

Study of gamma radiation induced damages and variation of oxygen enhancement ratio with radiation dose using Saccharomyces cerevisiae

In the present study, an attempt has been made to quantify Oxygen Enhancement Ratio (OER) and variation of OER as a function of dose with experimental and theoretical formulations using Saccharomyces cerevisiae D7, X2180 and rad 52. The study confirms that, the variation of OER with dose depends upon type of cell and repair proficiency of cells. A theoretical model has been formulated to estimate OER values. With the help of this model, OER value for any dose can be calculated in the exponential region of the survival curve without actually extending the experiment in that dose region.     

Assessment of radon concentration and external gamma radiation level in the environs of Narwapahar uranium mine,India and its radiological significance

In the environs of uranium mining, milling and processing facilities and in the uranium mineralized terrain, a little higher ambient radon concentration and gamma radiation level may be expected in comparison with natural background. The present study gives a brief account of atmospheric radon concentration, gamma absorbed dose rate and radiation dose received by the members of public in the vicinity of Narwapahar uranium mine. The ambient radon concentration in the air in the study area was found to vary from 5 to 107 Bq m⁻³ with geometric mean of 24 Bq m⁻³ and geometric standard deviation of 1.74 Bq m⁻³. The measured gamma absorbed dose rate in air at 1 m above the ground ranged from 87 to 220 nGy h⁻¹ with an overall arithmetic mean of 128 ± 18.5 nGy h⁻¹. The mean annual effective dose received by the members of public from inhalation of radon and its progeny and external gamma exposure was estimated to be 0.32 mSv year⁻¹, which is comparable to other reported values elsewhere.     

Estimation of the committed radiation dose resulting from gamma radionuclides ingested with food

The objective of the study was to estimate the value of the radiation dose absorbed in consequence of consumption of popular food products for individual age groups. Potatoes, corn and sugar beet were selected for the study. Edible parts of these plants were collected in experimental fields of the KWS Lochów Polska Sp. z o.o. seeding company in Kondratowice (Poland). On the basis of the obtained study results, it can be stated that in consequence of consumption of the selected food products, people may receive increased doses from both natural and artificial radioactive isotopes. The doses calculated for several age groups do not show any health hazards in consequence of consumption of the tested food. One of the determined radionuclides was ¹³⁷Cs; however, its presence in the absorbed dose is lower than the doses from natural radioactive isotopes, in particular ⁴⁰K.     

Response of portable gamma monitors for dose rate measurements under various radiation conditions

Journal of Radioanalytical and Nuclear Chemistry - Responses of the hand-held gamma monitors available for the ambient dose equivalent rate measurements in the Federation of Bosnia and Herzegovina...     

Influence of dose on particle size of colloidal silver nanoparticles synthesized by gamma radiation

Colloidal silver nanoparticles were synthesized by γ-irradiation-induced reduction method of an aqueous solution containing silver nitrate as a precursor in various concentrations between 7.40×10^?4 and 1.84×10^?3 M, polyvinyl pyrrolidone for capping colloidal nanoparticles, isopropanol as radical scavenger of hydroxyl radicals and deionised water as a solvent. The irradiations were carried out in a ⁶⁰Co γ source chamber at doses up to 70 kGy. The optical absorption spectra were measured using UV–vis spectrophotometer and used to study the particle distribution and electronic structure of silver nanoparticles. As the radiation dose increases from 10 to 70 kGy, the absorption intensity increases with increasing dose. The absorption peak λ_max blue shifted from 410 to 403 nm correspond to the increase of absorption conduction electron energy from 3.02 to 3.08 eV, indicating the particle size decreases with increasing dose. The particle size was determined by photon cross correlation spectroscopy and the results showed that the particle diameter decreases exponentially with the increase of dose. The transmission electron microscopy images were taken at doses of 20 and 60 kGy and the results confirmed that as the dose increases the diameter of colloidal silver nanoparticle decreases and the particle distribution increases.     

Estimation of ambient gamma radiation dose and drinking water radon concentration in coastal taluks of Uttara Kannada district,Karnataka

Journal of Radioanalytical and Nuclear Chemistry - This study assesses the ambient gamma dose rate and radon concentration in drinking water at different locations in few coastal taluks of Uttara...     

Effect of gamma radiation on fluoropolymers

A series of fluoropolymer films were synthesized by reacting several bisphenol monomers with 1,3‐bis(1,1,1,3,3,3‐hexafluoro‐2‐pentafluorophenyl methoxy‐2‐propyl)benzene via a nucleophilic aromatic substitution to form polyethers. The bisphenols used included two diphenol‐substituted spirodilactams (SDL; aliphatic and aromatic), biphenol, bisphenol A, bisphenol AF, bisphenol O, and bisphenol F to form seven different polymers. Polymers were irradiated by a Gamma beam 651‐PT at a dose rate of 10.5 kGy/h; the absorbed dose in each film was varied between 300 and 1000 kGy. The effect on the chemical structure upon radiation was studied by DSC, TGA, FTIR‐ATR, and NMR after and before irradiation. Thermal analysis showed a lessened thermal stability and a lower T_g after irradiation. Further, irradiation caused a decrease in molecular weight as a result of cleavage of sp³ bonds. These data allowed calculation of the radiochemical yield scission (G_s) for each of these polymers. The SDL aromatic system proved the most radiation‐resistant. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1617–1626, 2009     

Terrestrial absorbed dose rate measurement in the Jhangar valley of Pakistan

Specific activity of natural radionuclides; ²²⁶Ra, ²³²Th and ⁴⁰K were measured in the agricultural soil of eastern salt range of Pakistan using gamma ray spectrometry. The soil samples were collected within the ploughing region (up to 12 cm depth) and processed before analysis. The average specific activities of different radionuclides in the dry mass of soil samples were: ⁴⁰K, (666 Bq/kg), ²²⁶Ra (51 Bq/kg), and ²³²Th (59 Bq/kg). The average outdoor terrestrial absorbed dose rate in air from gamma radiation one meter above ground surface was found to be 93 nGy/h.     

Second hyperpolarizabilities (gamma) of bisimidazole and bistriazole benzenes: diradical character, charged state, and spin state dependences

The second hyperpolarizabilities of bisimidazole- and bistriazole-benzene compounds have been calculated at different levels of approximation to unravel the effects of diradical character as well as of charge and spin multiplicity. The largest second hyperpolarizabilities are associated with intermediate diradical character, provided positive charging does not compensate for this effect. For the neutral diradical bisimidazole compound, the singlet diradical species possesses a second hyperpolarizability two to three times larger than the corresponding triplet, demonstrating the possibility of spin state control of the third-order NLO responses for diradical species.     

Alteration of yeast activity by gamma radiation

Yeast is an important component in microbe based industrial technologies. Due to the techno-economic reasons, the fermentation technique has acquired renewed interest. The effect of -radiation on the fermentation reaction has been investigated. The studies show that exposure of the fermentation mixture to -radiation at 5 kGy enhance alcohol production, whereas irradiation at higher doses, viz., 10 kGy and 25 kGy caused a considerable reduction in the alcohol yield. Therefore, low dose irradiation of fermentation mixtures can be applied for increasing the alcohol production by about 25%.