Latest Research News on Gamma Radiation : July 21

[1] Effect of Gravity on Gamma Radiation Recoil-free resonant absorption of the 14.4-keV γ ray in Fe57 has been employed to measure the effect of gravity over a 75-ft vertical path in the Jefferson Laboratory, in an improved version of the experiment of Pound and Rebka. A Co57 source, initially 1.25 Ci, large-windowed proportional counters, and an enriched absorber foil 15 in. in diameter permitted a much increased counting rate. The employment of temperature-regulated ovens for source and absorbers and a redesigned monitor system to detect variations in waveform of the source velocity effected a reduction in systematic uncertainties. The result found was (0.9990±0.0076) times the value 4.905×10−15 of 2ghc2 predicted from the principle of equivalence. The range given here is the statistical standard deviation set by the number of counts involved. An estimated limit of systematic error is 0.010. [2] Conditioned aversion to saccharin resulting from exposure to gamma radiation “Rats tend to avoid a taste stimulus that has been associated with radiation exposure… ” even though the taste stimulus, a solution of saccharin, is ordinarily preferred. This “… conditioned aversion to saccharin is relatively radiosensitive, being effected by a 6-hr coupling with a 30-r dose of low-intensity (5 r/hr) gamma radiation. The conditioning appears to be dose-dependent in terms of strength of saccharin aversion and in the persistence of the aversion.” (PsycINFO Database Record (c) 2018 APA, all rights reserved) [3] Physics of environmental gamma radiation fields Calculated values are presented for total exposure rates and total photon fluxes and their energy and angular distributions as a function of height above the air-ground interface. Several illustrations of the use of these calculated quantities for designing instruments, interpreting data, planning field experiments, and calculating dose to people are included. (U.S.) [4] Excess Lifetime Cancer Risk due to Gamma Radiation in and Around Warri Refining and Petrochemical Company in Niger Delta, Nigeria Radioactivity measurements were carried out in and around Warri Refining and Petrochemical Company in the Niger Delta region of Nigeria for the naturally occurring radionuclides of 40K, 238U and 232Th. The values were used to determine the excess lifetime cancer risk (ELCR) and the radiation health hazard indices. Results show that the ELCR value within the company premises is 0.12×10-3 while the highest value was 0.17×10-3 from Ugborikoko Community. The internal health hazard index ranged from 0.02 – to 0.64 and the external health hazard index ranged from 0.02 – 0.33. All these values were less than the world permissible standards. It could be concluded that the potential carcinogenic risk from gamma radiation doses to the population in and around the refining and petrochemical company is low. [5] Synthesis of Selenium Nanoparticles by Bacillus laterosporus Using Gamma Radiation Aim: This study shows the possible synthesis of Selenium Nanoparticles (SeNPs) in aerobic optimized conditions using Bacillus laterosporus (B. laterosporus) bacterial strain. Methodology: B. laterosporus was used to reduce selenium ions (selenite anions) to SeNPs by fermentation in Luria-Bertani Enrichment (EM) medium. Optimization of fermentation conditions using two-level full factorial design was performed. SeNPs were further characterized by UV-Vis., DLS, TEM, FT-IR, EDX and XRD analysis. SeNPs synthesis by Gamma irradiated B. laterosporus cells at different radiation doses was reported. Evaluation the probability of B. laterosporus to synthesis SeNPs by fermentation in skimmed milk aerobically. A microtiterplate assay was used to evaluate the ability of SeNPs to inhibit the biofilm formation of Pseudomonas aeruginosa. Evaluating the antimicrobial activity of some antibiotic agents upon addition of SeNPs was performed. Results: B. laterosporus reduced the soluble, toxic, colorless selenium ions to the insoluble, non-toxic, red elemental SeNPs. Statistical analysis showed that the results were normally distributed. Temperature, incubation period and pH were significant factors in the fermentation process, in which the maximum SeNPs produced (8.37µmole/ml) was at temperature 37ºC, incubation period 48hr, pH7. The Gamma radiation exposure dose 1.5kGy gave the maximum SeNPs produced (10.01 µmole/ml). A pink color appear in the fermented milk revealing the formation of SeNPs-enriched milk. SeNPs inhibit the biofilm formation of Pseudomonas aeruginosa with a percentage reduction of 99.7%. SeNPs increase the antibacterial activity of fucidic acid by 13.6% and 28.5% against Escherichia coli and Staphylococcus aureus respectively. But with Gentamycin sulphate, no change in the antibacterial activity. Conclusion: SeNPs can be synthesized aerobically by the probiotic B. laterosporus bacterial strain. SeNPs can be incorporated in nutraceuticals and functional foods like milk also can be used to inhibit the bacterial biofilm formation and can be added to some antibacterial creams to enhance their antimicrobial activity. Reference [1] Pound, R.V. and Snider, J.L., 1965. Effect of gravity on gamma radiation. Physical Review140(3B), p.B788. [2] Garcia, J., Kimeldorf, D.J. and Koelling, R.A., 1955. Conditioned aversion to saccharin resulting from exposure to gamma radiation. Science. [3] Beck, H., 1972. Physics of environmental gamma radiation fields (No. CONF-720805–P1). [4] Emelue, H.U., Jibiri, N.N. and Eke, B.C., 2014. Excess lifetime cancer risk due to gamma radiation in and around Warri refining and petrochemical company in Niger Delta, Nigeria. Journal of Advances in Medicine and Medical Research, pp.2590-2598. [5] El-Batal, A.I., Essam, T.M., El-Zahaby, D.A. and Amin, M.A., 2014. Synthesis of selenium nanoparticles by Bacillus laterosporus using gamma radiation. Journal of Pharmaceutical Research International, pp.1364-1386.

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