Background: Gold nanoparticles with high atomic number and density have good potential to be used as contrast media in computed tomography. Objectives: In this study, we aimed to assess radiation dose and contrast enhancement performance of gold nanoparticles by measuring contrast to noise ratio compared to clinically used iodinated contrast agents at same concentrations. Contrast enhancement was evaluated in different tube voltages and currents. Materials and Methods: First, polyethylene glycol coated gold nanoparticles were synthesized with concentrations of 0.5 mM, 0.6 mM, and 0.7 mM. Gold nanoparticles and iodinated contrast media were scanned with CT imaging system at different tube voltages and time-current product. CT dose index (CTDI) value was measured by special phantom and electrometer. Improving in image contrast was assessed by contrast to noise ratio. Results: Results showed that gold nanoparticles in all concentrations and energies from 80 to 130 kVp display higher image contrastto-noise ratio (CNR) than iodinated contrast media. Image CNR was increased by increasing kVp and mAs. The CNR value was maximum at the voltage of 80 and 130 kVp for iodinated compounds and gold nanoparticles, respectively. The CNR value for gold nanoparticles at 130 kVp and 200 mAs was approximately five times higher than that of iodinated compounds. Conclusion: Gold nanoparticles could be a good candidate for optimizing CT imaging by lowering radiation dose as low as possible while enhancing the image contrast.

Methyl ethyl ether is formed by treating trimethyloxonium hexachloroantimonate with the strongly hindered base, 2,2,6,6-tetramethylpiperidyl-lithium; this reaction is attributed to the formation of an oxygen ylide followed by a Stevens-type rearrangement or intermolecular methylation.

Alipanah, M., Torkamanzehi, A. and Taghavi, H. 2010. Sex determination in ostrich (Struthio camelus) using DNA markers. Can. J. Anim. Sci. 90: 357Á360. Production of bird species such as ostrich (Struthio camelus) has been gaining increasing importance in Iran as well as many other countries. Ostrich, similar to many other species of birds, lacks sexual dimorphism, making it difficult to differentiate between males and females, especially at an early age, which can be problematic in breeding programs. Recently developed molecular genetic methods that utilize polymerase chain reaction (PCR) based techniques can facilitate rapid identification of the bird's sex in these species using a DNA sample, which can be easily extracted from blood or feather pulps. We successfully applied a PCR-based RFLP technique and sex chromosome primers for sex determination in a sample of 30 Ostrich chicks using DNA extracted from blood and feather pulps. Both DNA samples (blood and feather pulps) provided useful results. However, using feather pulps from 1-day-old chicks can provide an easy and inexpensive method for sex determination in ostrich.