Radionuclides of 238U, 232Th and 40K in beach sand of southern regions in Tamilnadu State, India (Post-Tsunami)

The natural radioactivity content of 238U, 232Th and 40K in beach sand of southern regions of Tamilnadu, India have been analyzed using gamma-ray spectroscopy. From the spectral analysis, the average radioactivity content of 238U, 232Th and 40K in beach sand samples are 8.77 ± 3.77, 76.48 ± 4.74 and 202.87 ± 26.72 Bq.kg-1, respectively. Univariate statistics has been applied successfully to assess the distribution of radionuclides and it shows that the decay series radionuclides such as 238U and 232Th are non-existence of normal distribution in the sands; however non-decay series radionuclide of 40K is distributed uniformly. Radiological parameters such as absorbed dose rate, annual effective dose equivalent, annual gonadal dose equivalent, radium equivalent, hazard index, gamma index, activity utilization index, alpha index and excess lifetime cancer risk have been calculated to know the complete radiological status of the coastal sands. The results of the present study indicate that the natural radioactivity content in the beach sands do not pose any radiation effect to the members of public in the southern region of Tamilnadu coast

Biosurfactants produced by Bacillus subtilis A1 and Pseudomonas stutzeri NA3 reduce longevity and fecundity of Anopheles stephensi and show high toxicity against young instars

Anopheles stephensi acts as vector of Plasmodium parasites, which are responsible for malaria in tropical and subtropical areas worldwide. Currently, malaria management is a big challenge due to the presence of insecticide-resistant strains as well as to the development of Plasmodium species highly resistant to major antimalarial drugs. Therefore, the present study focused on biosurfactant produced by two bacteria Bacillus subtilis A1 and Pseudomonas stutzeri NA3, evaluating them for insecticidal applications against malaria mosquitoes. The produced biosurfactants were characterized using FT-IR spectroscopy and gas chromatography-mass spectrometry (GC-MS), which confirmed that biosurfactants had a lipopeptidic nature. Both biosurfactants were tested against larvae and pupae of A. stephensi. LC50 values were 3.58 (larva I), 4.92 (II), 5.73 (III), 7.10 (IV), and 7.99 (pupae) and 2.61 (I), 3.68 (II), 4.48 (III), 5.55 (IV), and 6.99 (pupa) for biosurfactants produced by B. subtilis A1 and P. stutzeri NA3, respectively. Treatments with bacterial surfactants led to various physiological changes including longer pupal duration, shorter adult oviposition period, and reduced longevity and fecundity. To the best of our knowledge, there are really limited reports on the mosquitocidal and physiological effects due to biosurfactant produced by bacterial strains. Overall, the toxic activity of these biosurfactant on all young instars of A. stephensi, as well as their major impact on adult longevity and fecundity, allows their further consideration for the development of insecticides in the fight against malaria mosquitoes

Radionuclides of ²³⁸U, ²³²Th and ⁴⁰K in beach sand of southern regions in Tamilnadu State, India (Post-Tsunami)

218-230The natural radioactivity content of 238U, 232Th and 40K in beach sand of southern regions of Tamilnadu, India have been analyzed using gamma-ray spectroscopy. From the spectral analysis, the average radioactivity content of 238U, 232Th and 40K in beach sand samples are 8.77 ± 3.77, 76.48 ± 4.74 and 202.87 ± 26.72 Bq.kg-1, respectively. Univariate statistics has been applied successfully to assess the distribution of radionuclides and it shows that the decay series radionuclides such as 238U and 232Th are non-existence of normal distribution in the sands; however non-decay series radionuclide of 40K is distributed uniformly. Radiological parameters such as absorbed dose rate, annual effective dose equivalent, annual gonadal dose equivalent, radium equivalent, hazard index, gamma index, activity utilization index, alpha index and excess lifetime cancer risk have been calculated to know the complete radiological status of the coastal sands. The results of the present study indicate that the natural radioactivity content in the beach sands do not pose any radiation effect to the members of public in the southern region of Tamilnadu coast