Dose Effects of Ion Beam Exposure on Deinococcus Radiodurans: Survival and Dose Response

To explore the survival and dose response of organism for different radiation sources is of great importance in the research of radiobiology. In this study, the survival-dose response of Deinococcus radiodurans (E.coli, as the control) for ultra-violet (UV), γ-rays radiation and ion beam exposure was investigated. The shoulder type of survival curves were found for both UV and γ-ray ionizing radiation, but the saddle type of survival curves were shown for H+、 N+( 20keV and 30keV) and Ar+ beam exposure. This dose effect of the survival initially decreased with the increase in dose and then increased in the high dose range and finally decreased again in the higher dose range. Our experimental results suggest that D. radiodurans, which is considerably radio-resistant to UV and x-ray and γ-ray ionizing radiation, do not resist ion beam exposure.

Embryonic Hypertension Following Exposure to Teratogenic Doses of 5-Fluoro-2'-Deoxyuridine

The teratogenicity of 5-fluoro-2'-deoxyuridine (FdU) is well established. Previously, we have demonstrated that teratogenic doses of FdU produce hematomas and suggested that those hematomas produced skeletal malformations in chicken embryos. In this study, the cardiovascular effects of teratogenic doses of FdU in chicken embryos were studied. A dose of either 0.026 μg FdU or 0.030 μg FdU was injected into the yolk sacs of fertile chicken eggs containing embryos at Hamburger and Hamilton stages 17-19 of development. The embryos were then returned to the incubator. Aortic systolic and diastolic blood pressure,blood velocity and heart rate were measured at stages 21, 24 or 27 using a servonull system and Doppler ultrasound. In addition, mean arterial blood pressure, blood flow, and stroke volume were calculated from these data. Similar data were also recorded from uninjected and saline injected control embryos. Systolic and mean arterial blood pressures were significantly increased in FdU-treated embryos at stage 27. The other parameters measured or calculated were not significantly different from control embryos. Our study suggests that elevated systolic blood pressure in chicken embryos treated with FdU may lead to hematoma formation and subsequent birth defects

Effects of electron beam lithography process parameters on structure of silicon optical waveguide based on SOI

Electron beam lithography(EBL) is a key technology in the fabrication of nanoscale silicon optical waveguide. The influence of exposure dose, the main process parameter of EBL, on the structure profile of poly-methyl methacrylate(PMMA) after development was studied using a silicon on insulator(SOI) wafer with 220 nm top silicon as the substrate. The relationship between exposure dose and structure pattern width after development was analyzed according to the measurement results. The optimum exposure dose of 220 μC/cm^(2) was found to obtain a final structure consistent with the designed mask value through subsequent processes. At the same time, according to the image segmentation curve tracking technology, the contour extraction process of the dose test results was carried out, and the relationship among mask design value, exposure dose and two-dimensional roughness of boundary contour was analyzed, which can provide reference for the subsequent electron beam lithography of the same substrate material.

Concentrations of organophosphate esters in drinking water from the United Kingdom:Implications for human exposure

Data on the presence of organophosphate esters(OPEs)in drinking water and its significance as a pathway of exposure are limited.In this study,we measure for the first time,concentrations of eight OPEs in 50 UK drinking water samples.Arithmetic mean concentrations of ∑8OPEs were:6.4 and 11 ng/L in bottled(n=25)and tap water samples(n=25),respectively.Concentrations of ∑8OPEs in tap water(mean:11 ng/L)exceed significantly those in bottled water(mean:6.4 ng/L)(p˂0.01).Moreover,UK tap water is more contaminated with chlorinated,aryl-,and alkyl-OPEs than bottled water.The predominant OPEs detected were:tris(butoxyethyl)phosphate(TBOEP),tris(2-chloroethyl)phosphate(TCEP),and tris(2-chloroisopropyl)phosphate(TCIPP)with arithmetic mean concentrations in the two water sample types ranging between(3.5e3.8 ng/L),(0.60-3.0 ng/L),and(1.02-2.9 ng/L),respectively.Estimated daily intakes(EDIs)(mean and high-end exposure)via drinking water for different sectors of the UK population were:infants(0.93 and 6.4 ng/kg bw/day)˃toddlers(0.46 and 3.1 ng/kg bw/day)˃children(0.35 and 2.3 ng/kg bw/day)˃adults(0.28 and 2.1 ng/kg bw/day).Based on these data,exposure to ∑8OPEs via drinking water is much lower than via:food,indoor dust ingestion,inhalation,and dermal uptake for adults and toddlers.Reassuringly,our EDIs were lower than relevant reference dose(RfD)values.However,combining our drinking water ingestion data with exposure via other pathways revealed overall exposure to 2-ethylhexyl diphenyl phosphate(EHDPP)and TCIPP to approach health-based limit values for UK toddlers under a high-end exposure scenario.