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Chintāmani, India

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. Source

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 Source

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. Source

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. Source

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. Source

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