A theoretical and experimental dose rate study at a multipurpose gamma irradiation facility in Ghana

No Abstract. Journal of the Ghana Association Vol. 2 (3) 1999: pp.12-1

Pre-commisioning dosimetry at the radiation technology centre (RTC), Kwabenya

No Abstract. Journal of the Ghana Association Vol. 2 (3) 1999: pp.143-14

Neutron Activation Analysis of Chitin And Chitosan Extracted From Local Sea Crab Shells

Multielemental determinations in Chitin and Chitosan powders extracted from exoskeletons of local crab shells using Instrumental Neutron Activation Analysis (INAA) technique are reported. The samples were initially irradiated in a neutron thermal flux of 5 x 1011 n.cm-2s-1 in the 30kW Miniature Neutron Source Reactor (MNSR) at the Ghana Atomic Energy Commission (GAEC).Using a combination of short, medium and long irradiation schemes, fourteen elements were identified and quantified of which twelve (Al, Ca, Cl, Mg, Mn, Co, Cr, Cs, Eu, Fe, Sb, and Sc) were common to both samples. The study shows that these samples are rich sources of minor and major elements important for nutrition and growth in both plants and animals. Journal of the Ghana Science Association Vol. 9 (2) 2007: pp. 38-4

Simulation study of excitation functions for cyclotron production of 99mTc using TALYS code

Simulation studies for cyclotron production of Technetium-99m 99mTc) were conducted using a Nuclear Reaction Model Code (TALYS code) to generate reaction cross sections as function of proton bombardment energies for 100Mo (p,2n)99MTc reaction channel. The excitation functions data showed that an optimum proton energy range of 10 to 20 MeV was suitable for the production of 99mTc. Reaction channels of competing products or contaminants were also investigated. For practical production of 99mTc, the Mo-100 accelerator target must be enriched appropriately to reduce the levels of contaminants produced alongside the desired radionuclide. The trends and shapes of the excitation functions were similar to the EMPIRE Code simulation results

Peak Root and Starch Weights of Ten Early Bulking Cultivars of Cassava (Manihot Esculenta

Peak yields of total fresh root weight (TFRW), total dry root weight (TDRW) and total starch weight (TSW) of ten cassava (Manihot esculenta Crantz) cultivar are reported. Planting of the cassava cultivars was carried out in a randomized complete block design with three replications. The cassava roots were harvested first at 5 months after planting (MAP) and every month thereafter. The percentage starch content was determined using a UV-spectrophotometer at 690nm wavelength. Four main periods after planting could be identified for early bulking cultivars: (7 MAP - cultivars 115, DMA 030, HO 001 and UCC 096; 9 MAP - cultivars 126 and HO 015; 11 MAP - cultivars 90 and MQA98/11; 12 MAP - cultivars CR001/102 and HO 008). Time to achieve peak yield differed in some cultivars but was the same for TFRW, TDRW and TSW. Cassava cultivar HO 008 had the highest peak of TDRW and TSW in roots while cultivar MQA98/11 had the lowest. On dry weight basis, starch content was higher than 72%. Yield loss estimates due to delayed harvest of the cultivars are presented.. Journal of the Ghana Science Association Vol. 9 (2) 2007: pp. 54-6

Radiation Processing And Characterization Of Chitin And Chitosan Extracted From Crab Shells

The extraction and characterization of Chitin and Chitosan from crab shells (Callinectes sp.) obtained locally in Ghana is presented. The shells were finely milled and soaked in 10 % dilute hydrochloric acid (HCl) for 48 hr followed by de-proteinization using 2M sodium hydroxide (NaOH) solution for 24 hr to obtain Chitin. The Chitin was refluxed at 100 oC in 50 % NaOH for 7 hr to yield Chitosan. The Chitin and Chitosan were characterized by determining the de-acetylation, viscosity and average molecular weights. The degree of de-acetylation was determined to be 89.7 %. The viscosity of Chitosan in dilute acetic acid was measured and the average molecular weight estimated. The average molecular weight of dry gamma irradiated (up to 100kGy) Chitosan samples decreased with increasing dose. The results have been discussed in terms of radiation induced degradation of solids. Journal of the Ghana Science Association Vol. 9 (2) 2007: pp. 18-2

Stress characterization of surface damages on soda-lime glass using a nanocontact deformation method

A nanocontact deformation method was used to measure the local and graded residual stresses around contact damages. By analyzing influences of the residual stress on nanocontact deformation itself instead of measuring the secondary crack emanated from it, 0.65 ??m spatial resolution, which was superior to the highest level 1.8 ??m attained by previous indentation fracture mechanics tests with an acute cube-corner indenter, was obtained with a general Berkovich indenter. However, a stress model combined with the nanocontact deformation provided only average stress variation around the contact damages. Thus, a resolution of two principal components from the residual stress in a biaxial state has been attempted in this study. By introducing radial microcracks around artificial microVickers damages, a crack-normal circumferential stress component disappeared and a series of nanoindentations close to the microcrack line yielded a variation of the radial stress component. By comparing this result with the average stress variation mentioned above, the crack-opening circumferential stress was measured and showed a good consistency with the previous study in soda-lime glass. In addition, distinctive features of present method were compared with previous indentation fracture mechanics method.close1