Entrance Skin Dose (Radiation) Measurement and Evaluation (for all age groups) at the State Specialist Hospital, Okitipupa, Nigeria

This study was carried out on entrance skin dose (ESD) (Radiation) measurement and evaluation (for all age groups) at the State Specialist Hospital, Okitipupa, Ondo State, Nigeria. Entrance skin doses for randomly selected patients between 0-4 years, 5-9 years, 10-17 years and above 18 years old undergoing X-ray chest (Poster Anterior) examinations were measured and evaluation of the source-to-skin distance (SSD) records for the patients during the x-ray chest examinations were carried out. The mean ESD reported for chest PA projections were 66.43 µGy, 105.10 µGy, 215.76 µGy and 291.81 µGy respectively for age range 0 - 4 years, 5 - 9 years, 10 - 17 years and above 18 years. The ESD values reported in this present study were same with the NRPB recommendations of year 2000 of 50 µGy for newborn to 1-year-old, 70 µGy for 5 years and 120 µGy for 10 years old children. The values reported for age 1 to 4 years were lower than 0.1 mGy recommended and the mean ESD for age 5 to 9 years for chest PA examination was 0.11 mGy which is lower than the recommended 0.12 mGy. However, other values reported in this present study were compared with the guidance levels set by the International regulation bodies and were found to be within safe limits and they do not pose any significant health risk to the patients of all age ranges or the health workers. The effective radiation doses (ERDs) for all the age groups were computed, and by comparisons, it was found that the radiation risk factors (RRFs) are relatively low

Free radical mediated oxidative degradation of carotenes and xanthophylls

This article reviews the excited-state quenching, pro-vitamin A activity and anticarcinogenicity of carotenes and xanthophylls in relation to their chemical structures. Excited-state quenching improved with the length of the conjugated chain structure. Pro-vitamin A activity was dependent on the presence of at least one beta-ionyl ring structure. The effectiveness of carotenoids as antioxidants depended on their ability to trap peroxyl radicals with production of resonance-stabilized carotenyl radicals. The products identified from oxidations of carotenes and xanthophylls with molecular oxygen and other oxidizing agents are presented. The free radical-mediated mechanisms that have been proposed to account for the different classes of products are reviewed.Publisher PDFPeer reviewe

Influence of transition metal ion (mn4+) on mullite formation in a mixture of 50:50 Nigerian kaolin and calcined alumina

In the present investigation, 5 wt% chemical grade MnO2 was added in a mixture of 50:50 Nigerian sources of kaolin and superfine calcined alumina powder and effect of this transition metal ion on their physico-mechanical properties, phase and microstructural evolution were studied during heating in the temperature range of 1,400–1,650°C. The heated samples were found to be highly porous (>30%) in this entire temperature range. The doping of 5 wt% MnO2 in this mixture did not improved the densification, but resulted into higher flexural strength (26 MPa) at 1,400°C compared to 7 MPa in the undoped sample. At 1,650°C, the reverse trend was observed, the flexural strength of undoped sample was found to be higher (38 MPa) than doped sample (27 MPa). The XRD study revealed the formation of mullite as major and corundum as minor phases in both the samples. The microstructural study shown the presence of needle shaped mullite crystals and corundum grains. The presence of inter-granular and intra-granular pores in MnO2 doped samples might have reduced the strength at 1,650°C. The aspect ratio of mullite needle at 1,650°C was found to be higher in doped sample. The theoretical and experimental value of >4 for MnO2 ion has been validated