Government College for Women

Chintāmani, India

Government College for Women

Chintāmani, India

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Manjunatha H.C.,Government College for Women
Radiation Effects and Defects in Solids | Year: 2016

Dosimetric parameters such as efficiency of bremsstrahlung, probability of energy loss of beta during bremsstrahlung production, intensity and dose rate of high, medium and low-energy beta-emitting therapeutic radionuclides in different tissues of human organs are computed. These parameters are lower in adipose tissue than all other studied tissues. The efficiency, intensity and dose rate of bremsstrahlung increases with maximum energy of the beta nuclide (Emax) and modified atomic number (Zmod) of the target tissue. The estimated bremsstrahlung efficiency, intensity and dose rate are useful in the calculations of photon track-length distributions. These parameters are useful to determine the quality and quantity of the bremsstrahlung radiation (known as the source term). Precise estimation of this source term is very important in planning for radiotherapy and diagnosis. © 2016 Informa UK Limited, trading as Taylor & Francis Group


Manjunatha H.C.,Government College for Women
Applied Radiation and Isotopes | Year: 2014

A dosimetric study of beta-induced bremsstrahlung in bone is important in the field of radiation protection. The beta-induced bremsstrahlung spectra produced by 113 pure beta nuclides in the bone are computed. The spectral shapes are primarily responsible for variations in the shapes by depth-dose distributions. They are intended to provide a quick and convenient reference for spectral shapes and to give an indication of the wide variation in these shapes. The computed bremsstrahlung spectrum is used in the evaluation of bremsstrahlung dose in bone. The evaluated beta bremsstrahlung dose as a function of distance for the studied nuclides is also presented. The beta bremsstrahlung dose decreases with the increase in distance. Present work also estimates the dosimetric parameters of bremsstrahlung such as yield, intensity and dose rate of bremsstrahlung by various pure beta nuclides in tissues of human skeleton such as cortical bone, red marrow, yellow marrow, spongiosa and cartilage. The yield, intensity and dose rate of bremsstrahlung in the cortical bone are higher than that of red marrow, yellow marrow, spongiosa and cartilage. Hence cortical bone is more beta/bremsstrahlung radiosensitive than that of other tissues of human skeleton. The estimated bremsstrahlung efficiency, intensity, photon spectra and photon track-length distributions determine the quality and quantity of the radiation. Precise estimation of this source term is very important in planning for radiotherapy and diagnosis. © 2014 Elsevier Ltd.


Manjunatha H.C.,Government College for Women | Rudraswamy B.,Bangalore University
Health Physics | Year: 2013

Effective atomic numbers' (Zeff) effective electron density (Nel) for human organs and tissues have been computed in the energy region of 1 keV to 100 GeV using WinXCOM. The computed data of Zeff and Nel are tabulated. The computed values are compared with previous results. The computed data of Zeff and Nel for almost all tissues (34 tissues of different human organs) in the given energy range are not available in literature and find application in radiotherapy and dosimetry. Copyright © 2013 Health Physics Society.


Lathika Devi S.K.,Government College for Women | Sudarsana Kumar K.,Government College for Women | Balakrishnan A.,Grenoble Institute of Technology
Materials Letters | Year: 2011

Pure ZnO:Eu 3+ nanoparticles (∼ 50 nm) were prepared by a solution combustion method. ZnO and Eu 2O 3 were used as starting materials and dissolved in nitric acid. Citric acid was used as a fuel. The reaction mixture was heated at 350 °C resulting into a rapid exothermic reaction yielding pure nanopowders. The atomic weight concentration of Eu 3+ doped in ZnO was 20%. Transmission electron microscopy (TEM) was used to study the particle size and morphology. The nanopowders were characterized for phase composition using X-ray diffractrometry (XRD). Particle size distribution (PSD) analysis of ZnO: Eu 3+ showed particle sizes ranging from 30 to 80 nm.The photoluminescence emission spectra of ZnO:Eu 3+ nanostructures showed a strong band emission around 618 nm when excited with 515 nm wavelength. © 2010 Elsevier B.V. All rights reserved.


Aswathy Aromal S.,Mar Ivanios College | Dinesh Babu K.V.,Government College for Women | Philip D.,Mar Ivanios College
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2012

The development of new synthesis methods for monodispersed nanocrystals using cheap and nontoxic chemicals, environmentally benign solvents and renewable materials remains a challenge to the scientific community. The present work reports a new green method for the synthesis of gold nanoparticles. Four different ayurvedic arishtams are used for the reduction of Au3+ to Au nanoparticles. This method is simple, efficient, economic and nontoxic. Gold nanoparticles having different sizes in the range from 15 to 23 nm could be obtained. The nanoparticles have been characterized by UV-Visible spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) and FTIR analysis. The high crystallinity of nanoparticles is evident from bright circular spots in the SAED pattern and peaks in the XRD pattern. The synthesized gold nanoparticles show good catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol by excess NaBH4. The synthesized nanoparticles are found to exhibit size dependent catalytic property, the smaller nanoparticles showing faster activity. © 2012 Elsevier B.V. All rights reserved.


Manjunatha H.C.,Government College for Women
Nuclear Physics A | Year: 2016

We have studied the possible isotopes of superheavy nuclei Z=126 in the range 288≤A≥339 by studying through their α-decay properties. α-Decay half-life for the isotopes of Z=126 superheavy nuclei in the range 288≤A≥339 is performed within the Coulomb and proximity potential model for deformed nuclei (CPPMDN). The calculated α half-lives agree with the values computed using the Viola-Seaborg systematic, the universal curve of Poenaru et al. (2011) [61]; (2012) [62] and the analytical formulas of Royer (2000) [63]. To identify the mode of decay of these isotopes, the spontaneous-fission half-lives were also evaluated using the semiempirical relation given by Xu et al. (2008) [72]. As we could observe α chains consistently from the nuclei 288-306126, we have predicted that these nuclei could not be synthesized and detected experimentally via α decay as their decay half-lives are too small, which span the order 10-9 to 10-6 s. Most of the predicted, unknown nuclei in the range 307≤A≥326 were found to have relatively long half-lives. Of these the nuclei 307126, 318126, 319126, 320126 and 323-326126 were found to have long half-lives and hence could be sufficient to detect them if synthesized in a laboratory. © 2015 Elsevier B.V.


Manjunatha H.C.,Government College for Women
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2014

The external bremsstrahlung (EB) produced by beta particles such as from 90Sr-90Y, 147Pm and 204Tl in PbCl2, PbF2, Pb(NO3)2 and CdO were measured using NaI(Tl) crystal. The beta stopper technique is employed to measure the integral intensities above 100 keV energy in different absorber thicknesses. Attenuation of the external bremsstrahlung, excited by 90Sr-90Y, 147Pm and 204Tl beta-emitters in the same compounds has also been studied. The measured attenuation parameter is not constant with absorber thickness and it increases with increasing Zmod of the absorber. Whereas, the mass attenuation coefficient of gamma rays of equivalent energy is independent of the absorber thickness. This confirms that the attenuation of EB in an absorber does not conform to a single exponential law, unlike the absorption of monoenergetic gamma rays. Rather it may be a combination of a large number of exponential terms. © 2014 Elsevier B.V.


Manjunatha H.,Government College for Women
Indian Journal of Nuclear Medicine | Year: 2013

In the nuclear medicine, beta nuclides are released during the treatment. This beta interacts with bone and muscle and produces external Bremsstrahlung (EB) radiation. Present work formulated a new method to evaluate the EB spectrum and hence the Bremsstrahlung dose of therapeutic beta nuclides (Lu-177, Sr-90, Sm-153, I-153, Cs-137, Au-201, Dy-165, Mo-99, Sr-89, Fe-59, P-32, Ho-166, Sr-92, Re-188, Y-90, Pr-147, Co-60, K-42) in bone and muscle. The Bremsstrahlung yields of these beta nuclides are also estimated. Bremsstrahlung production is higher in bone than that of muscle. Presented data provides a quick and convenient reference for radiation protection and it can be quickly employed to give a first pass dose estimate prior to a more detailed experimental study.


Manjunatha H.C.,Government College for Women
Radiation Physics and Chemistry | Year: 2015

We report a study on influence of gamma irradiation on conductivity of YBa2Cu3O7. We have measured the mass attenuation coefficient, effective atomic number, electron density and electrical conductivity for various gamma sources of energy ranging from 0.084MeV to 1.330MeV (170Tm, 57Co, 141Ce, 203Hg, 51Cr, 113Sn, 22Na,137Cs, 60Co,22Na and 60Co). The measured values agree with the theoretical values. The values of these parameters have beenfound to change with energy and interaction of gamma. We find evidence for a variation of the electrical conductivity of YBa2Cu3O7 with the irradiated photon energy and this variation is shown in figures up to 105MeV. The variations of effective atomic number and electron density with energy are shown graphically for all photon interactions. Conductivity found to vary with the energy of the irradiated gamma radiation and interaction process of gamma. This kind of studies is important in the field of superconductivity. © 2015 Elsevier Ltd.


Manjunatha H.C.,Government College for Women
Radiation Physics and Chemistry | Year: 2016

Poly methyl methacrylate (PMMA) and Kapton polyimide are polymers used for various aerospace applications. We have measured the gamma attenuation parameters such as mass attenuation coefficient, effective atomic number and electron density of PMMA and Kapton polyimide for various gamma sources of energy ranging from 84keV to 1330keV (170Tm, 57Co, 141Ce, 203Hg, 51Cr, 113Sn, 22Na, 137Cs, 60Co, 22Na and 60Co). The measured values agree with the theoretical values. In the present work, we have also computed energy absorption build-up factors and exposure buildup factor of PMMA and Kapton polyimide for wide energy range (0.015-15MeV) up to the penetration depth of 40 mean free path using Geometrical Progression fitting method. The values of these parameters have been found to change with energy and interaction of gamma with the medium. The present study on gamma attenuation parameters are expected to be helpful in dosimetry, radiation shielding and other radiation physics based applications. The experimental data on the mass attenuation coefficients for Kapton and PMMA is not available in literature. To my knowledge data available e.g. in the NIST data base are based on extrapolations from the measurement of mass attenuation coefficients for the elements. Hence this work is first of its kind and it is useful in the various field of Polymers. © 2016 Elsevier Ltd.

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