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Chitosan can be deduced from chitin by simple chemical process. Chitosan has many applications and one of the promise application is used as nuclear shield by adopted it with some materials. Electron stopping power (SP) represents important parameter in tested the ability of any material to use it as nuclear shield. Therefore, stopping powers of electrons incident with different energies on chitin and chitosan have been calculated by using codes of National Institute of Standards and Technology (NIST) after modified it by built in the chemical structure and some other properties of chitin and chitosan in the codes. The results of total SP showed that chitosan has values larger than chitin but the differences are small and the maximum percentage difference ratio is 6.8% at 4 MeV electron energy. Total SP has approximately 35 Mev.cm2/g at 0.01 MeV electron energy, and decreasing with energy till to 1 MeV, then slowly increasing. In addition to total SP, the collision SP, radiative SP, density effect parameter, radiation yield, and electron range were calculated. The behaviors of the calculated parameters have been studied and explained. The obtained results suggested that chitosan may be used after mixing it with other materials as a shield from nuclear radiation, especially in low energies.

Chitin extraction has been the interest of many researchers using it as biopolymer in many applications. Many approaches have been adopted in chitin extraction. The aim of this work isto prepare chitin from chicken bone, proposing a new approach, using all chicken bone as source of chitin and recycling this waste instead of accumulation as refuse. A chemical method was used in extractingchitin (deproteinization and demineralization).The obtained chitin was characterized byFourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD), X-ray fluorescence(XRF).The best result obtained was in experiment E5,which are close to the standard results, but chitin extraction was 16.25% of the total weight of the chicken bone used in the experiment. Which is considered a high percentage compared to the state of research on chitin extraction from chicken feat.

This study was achieved to investigate the accumulation of some heavy metals included: Cadmium, Lead and Nickel in the tissues (gill, intestine, liver, muscles and skin) of Silurus triostegus Heckel, 1843 (Siluriformes, Siluridae) and its larval stage of the nematode Contracaecum sp. (Rhabditida, Anisakidae). As well as to assess the infection patterns of Contracaecum among S. triostegus specimens which were purchased fresh from the local market in Baghdad. One hundred and nine nematodes specimens in larval stage were recovered from the fish host; the overall prevalence of Contracaecum sp. was 38.6%. The sex of the host was not significantly (P ˃ 0.05) associated with the infection of this nematode. Results showed that the overall mean intensity of Contracaecum sp. was 6.41; mean intensity did not differ significantly (P ˃ 0.05) between the fish sexes.The lead (Pb) was the only element detected in all fish tissues investigated as well as in the parasite, while the cadmium and nickel elements were not detected in all specimens. Skin and muscles of the fish, as well the parasite Contracaecum sp. contained the lowest lead levels compared to other fish tissues (gill, intestine and liver), although no significant differences were noticed among all investigated tissues and the parasite regarding the concentration of Pb.