Hiriyur Mallaiah Somashekarappa

The presence of naturally occurring radionuclides is common in all living and non-living frameworks, which are part of our environment. The activity concentration of ⁴⁰K radionuclide was estimated using gamma spectrometry in some medicinal plants and transfer factors (TF), and Average Annual Committed Effective Dose (AACED) was evaluated. The standard methods were followed in the process of sample collection and processing. The mean activity concentrations of ⁴⁰K were 223 and 1330 Bq kg⁻¹ in soil and medicinal plants, respectively. The mean TF and AACED were found to be 6.5 and 8.2 μ Sv y⁻¹, respectively. Higher activity concentration was observed in some medicinal plants due to the selective and preferential uptake of this radionuclide depending on their medicinal utility. The study may help to form the database and safety regulations connected with ⁴⁰K activity in medicinal plants.

In this work, copper (Cu)-doped titanium dioxide (TiO₂) nanoparticles were prepared by co-precipitation. For studying the morphological properties, the copper doped titanium dioxide (TiO₂:Cu) nanocrystalline structures were characterised through powder X-ray diffraction and field emission scanning electron microscopy. The prepared TiO₂:Cu nanoparticles were annealed at two temperatures, namely, copper doped titanium dioxide annealed at 723 K temperayure (TC₁) and copper doped titanium dioxide annealed at 1073 K temperayure (TC₂). The annealed samples were exposed to gamma radiation of 10-Gy-to-25-kGy doses. Thermoluminescence and dosimetric properties were evaluated using a thermoluminescent dosemeter reader. The glow curves of the TiO₂:Cu nanoparticles were analysed. The thermoluminescence (TL) response of samples exhibited good linearity between 100 Gy and 10 kGy with high sensitivity of 1755.25 (TC₁) and 5587.06 (TC₂) counts g⁻¹Gy⁻¹ and a minimum detectable dose of 2.9666 Gy (TC₁) and 0.4892 Gy (TC₂). The fading of signals was observed by 12% for TC₁ and 10% for TC₂ samples after a week of storage.

The shock wave impact effects has been studied on PVA (Poly Vinyl Alcohol), thin films in view of morphological and electrical property changes. The PVA films of thickness around 0.25 mm are subjected to shock waves impact of Mach number around 1.7 to 1.8. The samples are subjected to 0, 25, 50, 100 and 150 number of shocks, in a time interval of around 15 seconds between the shocks. The shock waves are generated with an in-house developed shock tube capable of producing shock waves of Mach number up to 2. The films are further characterized with FTIR, UV-Visible spectral analysis for chemical and physical changes and the EDAX, SEM image analysis further confirmed the effects. The trend in the I-V characteristics and the impedance data obtained, clearly shows the significant increase in the conductivity of PVA films. Thus, shock wave impact method proves to be another method of treatment of materials and the results obtained promises about the possible electrical applications of PVA films.

Resistance to anticancer drugs limits the effectiveness of chemotherapy in cancers. Melanoma cell lines B16F10C and A375C (parental) and B16F10R and A375R (drug-resistant sublines) were used to test radiation sensitization potential of valproic acid (VPA), an inhibitor of Histone deacetylase2 (HDAC2) and LDN193189 (BMP inhibitor). Inhibitors of other signaling pathways were tested for cross-resistance with the resistant cell lines. Cells were pretreated with low concentrations of VPA/ LDN193189 and exposed to 2 Gy radiation for radiation sensitization experiments. Assays-3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT), live/dead, clonogenic, and melanin estimation were performed to test the effects of radiation sensitization. Interactions of VPA and HDAC2 were studied in silico. Dose-dependent growth inhibition was observed with all tested drugs. Radiation sensitization of melanoma cells with low dose of VPA induced synergistic cell death, decreased clonogenicity, and decreased melanin content. In silico docking showed two stable interactions between Arg39 of HDAC2 and VPA. In conclusion, pretreatment with low doses of VPA has a potential for sensitizing melanoma cells to low doses of radiation. The binding of VPA to HDAC2 reverses the drug resistance in melanoma and induces the cell death. Sensitization effects of VPA can be used for targeting drug-resistant cancers.

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Hydrogel nanocomposites of polyvinyl alcohol (PVA) filled with gold nanoparticles (Au NPs) were synthesised using gamma irradiation technique. Structural, optical, and morphological characterisation was performed using powder XRD, UV-vis, FESEM, and TEM techniques. Inclusion of Au NPs at the time of crosslinking may have reduced the binding sites of PVA matrix, which resulted in high-swelling capacity of Au/PVA hydrogel nanocomposites. The increase in mechanical stability of the Au/PVA hydrogel nanocomposites has been observed and it may be due to increase in the crystallinity percentage with increased Au NPs in PVA matrix. These nanocomposites may fulfil the increasing demand for multifunctional hydrogel with enhanced swelling and mechanical properties.