RESUMO
Background: Gold nanoparticles [GNPs] play an important role in medical, health and environmental applications. All kinds of microorganisms were found to be able to synthesize GNPs. The optimization of laboratory conditions for achieving more economical benefits of mass production has been studied widely
Methods: This study assesses the enhancing effect of low-level X-rays on the biosynthesis of GNPs by Actinomycetals. The isolated Actinomycetes were grown aerobically in MGYP broth media. The harvested bacteria were suspended in 50 mL aqueous HAuCl4 in 12 Erlenmeyer flask. Each group contained4 flasks. 2 groups of samples were irradiated by 30 mGy and 5 mGy X-rays respectively. The third group as control remained without irradiation. The solutions were shake- incubated for 120 h
Results: After 5 days, the color of first group samples changed from milky to purple, while the color changing occurred after 10 days in the 2nd group samples and the control samples. The UV-vis absorption spectrometry of the irradiated aqueous medium by 30 mGy X-rays confirmed the formation of GNPs
Conclusion: The findings showed that 30 mGy X-rays stimulated the microorganism to form GNPs in a half time in comparison to other groups
RESUMO
Background: Dithiocarbamates, the main group of fungicides, are used to control about 400 pathogens in more than 70 crops. These pesticides are widely applied to crops including potato, cereal, apple, pear and leafy vegetables throughout the world since 1960. From the late 1980s, using these fungicides has caused much debate among regulators about their long-term effects on consumers and occupational users
Method: In this study the residues of Dithiocarbamates in cucumber and tomato using the colorimetric method [Keppel method] was measured. Respectively 80 and 45 samples of greenhouse cucumber and tomato were collected from Zanjan vegetables center in autumns and winter 2013. The samples were analyzed in 4 treatments of: unwashed, washing with water, washing whit detergent and peeling
Result: The results showed that the average concentration of Dithiocarbamates residues in unwashed greenhouse cucumber and tomatoes were 384.5 micro g/kg and 65 micro g/kg respectively. 35% and 5% of unwashed and water washed cucumber and tomato samples [respectively] had higher Dithiocarbamates residue than MRL recommended by Institute of Standards and Industrial Research of Iran [0.5mg/kg]
Conclusion: The treatments of washing and peeling had significant effect on the reduction of Dithiocarbamates residues in the all samples