http://nopr.niscair.res.in/handle/123456789/10473 <b>Special Issue on Accelerators and Low Level Radiation Safety — Part 2<b> Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/10491 Title: Radiochromic behaviour of bromocresol green-polyethylene glycol system towards <img src='/image/spc_char/gamma2.gif' border=0>-radiation <br/> <br/>Authors: Bera, Anuradha; Ram, Surendra; Singh, S K; Kumar, D; Kacchwaha, A; Tiwari, B L; Vaijapurkar, S G <br/> <br/>Abstract: Active BCG-PEG radiochromic liquid system has been formulated for potential application as threshold dosimeter for gamma radiation that can be visually evaluated. PEG concentrations have been varied to see their effect on the radiation sensitivity of these systems. The response characteristics are monitored both visually and by UV-Vis spectrometry. The minimum visually detectable level achieved with the formulated solution is 0.2 kGy, where the solution showed a sharp colour change from green to yellow. The detection level could be moved to the higher side by increasing the concentration of PEG in the formulation. Preliminary dose dependence studies have been carried out in the range 0.3-7.5 kGy/hr. <br/> <br/>Page(s): 837-839 http://nopr.niscair.res.in/handle/123456789/10490 Title: Present status of radiochromic techniques for nuclear radiation measurements <br/> <br/>Authors: Vajapurkar, S G; Bera, Anuradha <br/> <br/>Abstract: Various developmental stages of radiochromic dosimetry in kGy to mGy range depending on its applications in radiation processing industries, radiological safety, medical sciences, nuclear or dirty bomb exposition and radiation accident have been described. Leuco dyes, <i style="">p</i>H sensitive dye with halogen containing compound and radiation induced solid state polymerization are the basic chemical methods presently in use for radiochromic techniques. The present status including achievements, limitations and R&amp;D required for further improvements of accurate and precision measurements has also been highlighted. The reader system for mapping of radiation distributions in patient dosimetry and accurate measurements of personal doses in any nuclear or radiological accident scenario are also elaborated. <br/> <br/>Page(s): 830-836 http://nopr.niscair.res.in/handle/123456789/10489 Title: Graft-copolymerization of N-vinyl-2-pyrrolidone onto isotactic polypropylene film by gamma radiation using peroxidation method <br/> <br/>Authors: Sehgal, Teena; Rattan, Sunita <br/> <br/>Abstract: Isotactic polypropylene (IPP) films were modified through radiation-induced grafting of N-vinyl-2-pyrrolidone (NVP) with the aim of preparing hydrogels. The radioactive isotope cobalt-60 was used as the source of gamma radiation. A plausible mechanism of grafting has been proposed. The grafting conditions were optimized with respect to monomer concentration, time, temperature and amount of solvents. The structures of grafted films were characterized by FTIR, AFM and SEM studies. IPP-g-NVP films were investigated for their swelling behaviour as a function of different <i>pH</i> solutions. The prepared grafted films can have potential applications in the fields of controlled drug delivery systems. <br/> <br/>Page(s): 823-829 http://nopr.niscair.res.in/handle/123456789/10488 Title: Estimation of radioactivity in tobacco <br/> <br/>Authors: Nain, Mahabir; Gupta, Monika; Chauhan, R P; Kant, K; Sonkawade, R G; Chakarvarti, S K <br/> <br/>Abstract: The link between cigarette smoke and cancer has long been established. Smokers are ten times at greater risk of developing lung cancer than that of non-smokers. Tobacco fields and plants also have higher concentration of uranium and consequently large contents of ²¹⁰ Po and ²¹⁰ Pb belonging to uranium and radium decay series. These radio-nuclides have long association with tobacco plants. ²¹⁰Pb and ²¹⁰Po, decay products of the uranium series get dissolved in water and are first transported into plants and subsequently to the human being. Also, the uptake of radio nuclides into roots from the soils and phosphate fertilizers along with direct deposition of ²¹⁰Pb by rainfall represents the principal mechanism of incorporation of ²¹⁰Pb and ²¹⁰Po into the tobacco plants. Uranium present in soil enters the plants through roots and gets distributed in various parts of the tobacco plants. This phenomenon may cause high intake of uranium and its radioactive decay products leading to harmful effects in human being. In the present work, Gamma spectrometry (HPGe detector of high-resolution gamma spectrometry system) has been used at Inter University Accelerator Center (IUAC), New Delhi, for the measurement of activity concentrations of ²³⁸U, ²³²Th and ⁴⁰K in some tobacco samples. The alpha radioactivity of the leaves of the tobacco plants was measured using plastic track detectors LR-115 Type-II manufactured by Kodak. Measurement of track densities (track cm^-2 day^-1) shows variation on the upper face and the bottom face of the leaves for the plants. The track density due to alpha particles is higher at bottom face as compared to top face of the leaves <br/> <br/>Page(s): 820-822